Sample records for vertical ground-coupled heat

  1. Modelling of a vertical ground coupled heat pump system by using artificial neural networks

    Microsoft Academic Search

    Hikmet Esen; Mustafa Inalli

    2009-01-01

    This paper describes the applicability of artificial neural networks (ANNs) to estimate of performance of a vertical ground coupled heat pump (VGCHP) system used for cooling and heating purposes experimentally. The system involved three heat exchangers in the different depths at 30 (VB1), 60 (VB2) and 90 (VB3)m. The experimental results were obtained in cooling and heating seasons of 2006–2007.

  2. Vertical-borehole ground-coupled heat pumps: A review of models and systems

    Microsoft Academic Search

    H. Yang; P. Cui; Z. Fang

    2010-01-01

    A large number of ground-coupled heat pump (GCHP) systems have been used in residential and commercial buildings throughout the world due to the attractive advantages of high efficiency and environmental friendliness. This paper gives a detailed literature review of the research and developments of the vertical-borehole GCHP technology for applications in air-conditioning. A general introduction on the ground source heat

  3. Simulation and experimental verification of vertical ground-coupled heat pump systems

    Microsoft Academic Search

    Kavanaugh

    1985-01-01

    This study compared the performance of piping arrangements buried vertically in the ground to serve as couplings between water-to-air heat pumps and the earth which is the sink or source of heat. A second purpose was to develop and analyze methods of designing and simulation system performance. The study is limited to ground-coupling designs that can be installed in bore

  4. A Modified Analytical Method for Simulating Cyclic Operation of Vertical U-Tube Ground-Coupled Heat Pumps 

    E-print Network

    Dobson, M. K.; O'Neal, D. L.; Aldred, W.

    1994-01-01

    A modified analytical model is presented which discretizes the ground-coupled heat exchanger of a ground-coupled heat pump and utilized a separate cylindrical source solution for each element. First law expressions are utilized for each element...

  5. A Simplified Procedure for Sizing Vertical Ground Coupled Heat Pump Heat Exchangers for Residences in Texas 

    E-print Network

    O'Neal, D. L.; Gonzalez, J. A.; Aldred, W.

    1994-01-01

    , ground thermal properties (density, thermal conductivity, and specific heat), and outdoor weather. A set of sizing charts were developed from the model runs that could provide quick reference on the size of the ground heat exchanger. Corrections...

  6. A parametric study on the exergoeconomic assessment of a vertical ground-coupled (geothermal) heat pump system

    Microsoft Academic Search

    Onder Ozgener; Arif Hepbasli; Leyla Ozgener

    2007-01-01

    An exergoeconomic model of a vertical ground-source heat pump residential heating system presented in this study uses exergy and cost energy mass (EXCEM) methods. The data obtained from a ground-source heat pump (GSHP) residential heating system installed at the Solar Energy Institute, Ege University, Turkey, are utilized for calculations at different reference temperature values in the range 0–25°C. The performance

  7. NUMERICAL STUDY OF HEAT TRANSFER OF A SINGLE U-TUBE IN VERTICAL GROUND-COUPLED HEAT PUMP SYSTEMS

    Microsoft Academic Search

    C F Ma; Y T Wu

    The heat transfer rate of a single U-tube ground heat exchanger was studied numerically. First, a 3D 60-m full scale computational model of a working single U-tube ground heat exchanger was built and numerical simulation was performed. The simulation was validated by comparing numerically calculated results with experimental results. After that, two models are built to compute the heat extraction

  8. The Design of Ground-Coupled Heat Pump Systems 

    E-print Network

    Parker, J. D.

    1985-01-01

    Ground-coupled heat pumps are being installed in increasing numbers due to proven performance and economy. The overall thermal resistance between the ground coupling fluid and a given type of surrounding soil is affected by pipe material, wall...

  9. (Assessment of ground-coupled heat pumps)

    SciTech Connect

    Mei, V.C.

    1989-12-05

    The objectives of the third working meeting were to assess the accomplishments to date in direct-expansion ground-coupled heat exchanger study and to discuss what should be done in the future. The design concepts presented by each participating country are quite similar. Annex XV enables us to exchange information on experimental and analytical results. The third working meeting was hosted by Oberoesterreichische Kraftwerke Aktiengesellschaft (OKA) Power Co. at Linz, Austria and by the Department of Thermal Engineering, Graz University of Technology at Graz, Austria. The meeting was chaired by Dr. O.J. Svec of Canada. The next working meeting will be held in Japan. The United States will host the last meeting at ORNL in September 1990. 5 refs.

  10. A ground-coupled storage heat pump system with waste heat recovery

    Microsoft Academic Search

    D. C. Drown; K. R. D. Braven; T. P. Kast

    1992-01-01

    This paper reports on an experimental single-family residence that was constructed to demonstrate integration of waste heat recovery and seasonal energy storage using both a ventilating and a ground-coupled heat pump. Called the Idaho energy Conservation Technology House, it combines superinsulated home construction with a ventilating hot water heater and a ground coupled water-to-water heat pump system. The ground heat

  11. Thermal and economic assessment of ground-coupled storage for residential solar heat pump systems

    NASA Astrophysics Data System (ADS)

    Choi, M. K.; Morehouse, J. H.

    1980-11-01

    This study performed an analysis of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating were determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, D.C., Fort Worth, Tex., and Madison, Wis. The results indicate that without tax credits a combined solar/ground-coupled heat pump system for space heating and cooling is not cost competitive with conventional systems. Its thermal performance is considerably better than non-ground-coupled solar heat pumps in Forth Worth. Though the ground-coupled stand-alone heat pump provides 51% of the heating and cooling load with non-purchased energy in Forth Worth, its thermal performance in Washington and Madison is poor.

  12. Short communication Optimization of hybrid ground coupled and air source heat pump systems

    E-print Network

    Fernández de Córdoba, Pedro

    Short communication Optimization of hybrid ­ ground coupled and air source ­ heat pump systems 2008 Accepted 14 January 2010 Available online 28 January 2010 Keywords: Ground coupled heat pump Air to water heat pump Thermal storage device Hybrid HVAC system Energy efficiency Numerical simulation a b

  13. Horizontal Ground Heat Exchanger Design for Ground-Coupled Heat Pumps

    Microsoft Academic Search

    S. A. M. Said; M. A. Habib; E. M. A. Mokheimer; N. Al-Shayea; M. Sharqawi

    Ground-source heat pump (GSHP) is used as an all in clusive term for a variety of systems that use the ground, ground water and surfa ce water as a heat source and sink. There are several examples of various types of GSHPs which ar e subdivided into ground-coupled heat pumps (GCHPs), ground water heat pumps (GWHPs) and surfac e water

  14. Thermal and economic assessment of ground-coupled storage for residential solar heat pump systems

    Microsoft Academic Search

    M. K. Choi; J. H. Morehouse; P. J. Hughes

    1980-01-01

    This study performed an analysis of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating were determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, D.C., Fort

  15. Comparison of ground-coupled solar-heat-pump systems to conventional systems for residential heating, cooling and water heating

    Microsoft Academic Search

    M. K. Choi; J. H. Morehouse; P. J. Hughes

    1981-01-01

    An analysis is performed of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating is determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, DC; Fort Worth,

  16. Response Functions and Thermal Influence for Various Multiple Borehole Configurations in Ground Coupled Heat Pump Systems

    Microsoft Academic Search

    METKA PESL; DARKO GORICANEC; JURIJ KROPE

    2007-01-01

    Ground coupled heat pump (GCHP) utilizes the immense renewable storage capacity of the ground as a heat source or sink to provide space heating, cooling, and domestic hot water. GCHP systems are generally comprised of water source heat pumps and ground heat exchangers (GHEs). Consisting of closed- loop of pipes buried in boreholes, ground heat exchangers (GHEs) are devised for

  17. Experimental studies on a ground coupled heat pump with solar thermal collectors for space heating

    Microsoft Academic Search

    Chen Xi; Yang Hongxing; Lu Lin; Wang Jinggang; Liu Wei

    2011-01-01

    This paper presents experimental studies on a solar-assisted ground coupled heat pump (SAGCHP) system for space heating. The system was installed at the Hebei Academy of Sciences in Shijiazhuang (lat. N38°03?, long. E114°26?), China. Solar collectors are in series connection with the borehole array through plate heat exchangers. Four operation modes of the system were investigated throughout the coldest period

  18. GROUND-COUPLED HEAT-PUMP-SYSTEM EXPERIMENTAL RESULTS* Philip D. Metz

    E-print Network

    Oak Ridge National Laboratory

    #12;GROUND-COUPLED HEAT-PUMP-SYSTEM EXPERIMENTAL RESULTS* Philip D. Metz _Solar and Renewables house in Upton, Long Island, New York has been heated and cooled by a liquid source heat pump using- saving construction with a heating load of 7.8 X 106 J/OC-day (4.1 X 103 Btu/ OF-day). The heat pump used

  19. Ground-Coupled Heating-Cooling Systems in Urban Areas: How Sustainable Are They?

    ERIC Educational Resources Information Center

    Younger, Paul L.

    2008-01-01

    Ground-coupled heating-cooling systems (GCHCSs) exchange heat between the built environment and the subsurface using pipework buried in trenches or boreholes. If heat pumps in GCHCSs are powered by "green electricity," they offer genuine carbon-free heating-cooling; for this reason, there has been a surge in the technology in recent years.…

  20. Numerical and experimental analysis of a horizontal ground-coupled heat pump system

    Microsoft Academic Search

    Hikmet Esen; Mustafa Inalli; Mehmet Esen

    2007-01-01

    The main objective of this work is to evaluate a heat pump system using the ground as a source of heat. A ground-coupled heat pump (GCHP) system has been installed and tested at the test room, University of Firat, Elazig, Turkey. Results obtained during experimental testing are presented and discussed here. The coefficient of performance (COPsys) of the GCHP system

  1. Ground coupled solar heat pumps: analysis of four options

    SciTech Connect

    Andrews, J.W.

    1981-01-01

    Heat pump systems which utilize both solar energy and energy withdrawn from the ground are analyzed using a simplified procedure which optimizes the solar storage temperature on a monthly basis. Four ways of introducing collected solar energy to the system are optimized and compared. These include use of actively collected thermal input to the heat pump; use of collected solar energy to heat the load directly (two different ways); and use of a passive option to reduce the effective heating load.

  2. Efficiency improvement of a ground coupled heat pump system from energy management

    E-print Network

    Fernández de Córdoba, Pedro

    to improve the efficiency of a ground coupled heat pump air conditioning system by adapting its produced coupled heat pump Energy efficiency Numerical simulation a b s t r a c t The installed capacity of an air thermal energy to the actual thermal demand. For this purpose, an air conditioning system composed

  3. Optimization of hybrid – ground coupled and air source – heat pump systems in combination with thermal storage

    Microsoft Academic Search

    N. Pardo; Á. Montero; J. Martos; J. F. Urchueguía

    2010-01-01

    Ground coupled heat pumps are attractive solutions for cooling and heating commercial buildings due to their high efficiency and their reduced environmental impact. Two possible ideas to improve the efficiency of these systems are decoupling energy generation from energy distribution and combining different HVAC systems. Based on these two ideas, we present several HVAC configurations which combine the following equipments:

  4. Performance prediction of a ground-coupled heat pump system using artificial neural networks

    Microsoft Academic Search

    Hikmet Esen; Mustafa Inalli; Abdulkadir Sengür; Mehmet Esen

    2008-01-01

    This paper describes the applicability of artificial neural networks (ANNs) to predict performance of a horizontal ground-coupled heat pump (GCHP) system. Performance forecasting is the precondition for the optimal control and energy saving operation of heat pump systems. ANNs have been used in varied applications and they have been shown to be particularly useful in system modelling and system identification.

  5. Analysis and field evaluation of an advanced ground-coupled heat pump system

    Microsoft Academic Search

    V. D. Baxter; M. A. Catan; H. M. Hughes; P. J. Hughes; R. A. ONeil

    1986-01-01

    This paper addresses the performance of a ground-coupled heat pump (GCHP) system with a water-source heat pump (WSHP) package designed expressly for such systems for a northern climate. The research objective was to minimize the life-cycle cost (LCC) of a GCHP system by optimizing the design of both the heat pump package and the ground heat exchanger in concert. The

  6. Experimental study of a ground-coupled heat pump combined with thermal solar collectors

    Microsoft Academic Search

    V. Trillat-Berdal; B. Souyri; G. Fraisse

    2006-01-01

    This paper presents the experimental study of a ground-coupled heat pump used in a 180m2 private residence and combined with thermal solar collectors. This process, called GEOSOL, meets domestic hot water and heating–cooling building energy needs. Solar heat is used as a priority for domestic hot water heating and when the preset water temperature is reached, excess solar energy is

  7. Experimental analysis of direct-expansion ground-coupled heat pump systems

    Microsoft Academic Search

    V. C. Mei; V. D. Baxter

    1991-01-01

    Direct-expansion ground-coil-coupled (DXGC) heat pump systems have certain energy efficiency advantages over conventional ground-coupled heat pump (GCHP) systems. Principal among these advantages are that the secondary heat transfer fluid heat exchanger and circulating pump are eliminated. While the DXGC concept can produce higher efficiencies, it also produces more system design and environmental problems (e.g., compressor starting, oil return, possible ground

  8. Ground-Coupled Heat Pump Applications and Case Studies 

    E-print Network

    Braud, H. J.

    1989-01-01

    The paper presents an overview of ground loops for space-conditioning heat pumps, hot water, ice machines, and water-cooled refrigeration in residential and commercial applications. In Louisiana, a chain of hamburger drive-ins uses total ground...

  9. Optimization of Advanced Ground-Coupled Heat Pump Systems A heat pump is a technology in which heating and cooling are provided by a single piece of equipment.

    E-print Network

    Wisconsin at Madison, University of

    Optimization of Advanced Ground-Coupled Heat Pump Systems A heat pump is a technology in which heating and cooling are provided by a single piece of equipment. In a Ground Coupled Heat Pump (GCHP) system a length of pipe is buried in the ground and the ground acts as a reservoir to store the heat

  10. Sub-hourly simulation of residential ground coupled heat pump systems

    Microsoft Academic Search

    Michaël Kummert; Michel Bernier

    2008-01-01

    Residential Ground Coupled Heat Pump systems are usually characterised by an ON\\/OFF behaviour of the heat pump with typical cycling frequencies of 1—4 cycles per hour. The ground loop fluid pump has the same ON\\/OFF behaviour and the borehole heat exchanger operates either in full flow or no flow conditions. Typical hourly simulations of GCHP systems use steady-state models for

  11. Antifreeze acceptability for ground-coupled heat pump ground loops in the United States

    SciTech Connect

    Den Braven, K.R. [Univ. of Idaho, Moscow, ID (United States). Dept. of Mechanical Engineering

    1998-10-01

    When designing and installing closed-loop ground-coupled heat pumps systems, it is necessary to be aware of applicable environmental regulations. Within the United States, nearly half of the states have regulations specifying or restricting the use of particular antifreezes or other fluids within the ground loop of a ground-coupled heat pump system. A number of other states have regulations pending. While all of these regulations are based on the need to preserve groundwater and/or aquifer quality, the list of acceptable antifreezes varies among those states with specified fluids. Typical antifreezes in use include ethylene glycol, propylene glycol, brines, alcohols, and potassium acetate. Each of these has its benefits and drawbacks. The status of the regulations has been determined for all of the states. An overview of the regulations is presented in this paper, along with a summary of the states` concerns.

  12. Comparison of ground-coupled solar-heat-pump systems to conventional systems for residential heating, cooling and water heating. Final report

    Microsoft Academic Search

    M. K. Choi; J. H. Morehouse; P. J. Hughes

    1981-01-01

    An analysis is performed of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating is determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, DC, Fort Worth,

  13. Experimental analysis of direct-expansion ground-coupled heat pump systems

    SciTech Connect

    Mei, V.C.; Baxter, V.D.

    1991-09-01

    Direct-expansion ground-coil-coupled (DXGC) heat pump systems have certain energy efficiency advantages over conventional ground-coupled heat pump (GCHP) systems. Principal among these advantages are that the secondary heat transfer fluid heat exchanger and circulating pump are eliminated. While the DXGC concept can produce higher efficiencies, it also produces more system design and environmental problems (e.g., compressor starting, oil return, possible ground pollution, and more refrigerant charging). Furthermore, general design guidelines for DXGC systems are not well documented. A two-pronged approach was adopted for this study: (1) a literature survey, and (2) a laboratory study of a DXGC heat pump system with R-22 as the refrigerant, for both heating and cooling mode tests done in parallel and series tube connections. The results of each task are described in this paper. A set of general design guidelines was derived from the test results and is also presented. 12 refs., 11 figs., 1 tab.

  14. Preliminary study of a gas burner-driven and ground-coupled heat pump system

    SciTech Connect

    Hsu, P.F. [Florida Inst. of Technology, Melbourne, FL (United States). Mechanical and Aerospace Engineering Programs

    1995-12-31

    To address the concerns for higher energy efficiency and the immediate phase out of the chlorofluorocarbons (CFCs), a new gas burner-driven, ground-coupled heat pump (GBGCHP) system is proposed for study. The new system is energy efficient and pose no environmental problem. There are three unique features in the proposed system: (1) a patented gas burner-driven compressor with a floating diaphragm piston-cylinder for energy efficiency and accommodating variable load, (2) the ground coupled water-to-air heat exchangers for high coefficient of performance (COPs), and (3) the new refrigerants based on fluoroiodocarbons (FICS) with very little ozone depletion and global warming potential. A preliminary analysis of a prototype heat pump with 3 ton (10.55 kW) heating capacity is presented. The thermodynamics analysis of the system shows that the steady state COP rating higher than 7 is possible with the system operating in heating mode. Additional research work for the GBGCHP system, especially the FICs` thermodynamic properties in the superheated region, is also described.

  15. Potential of autonomous ground-coupled heat pump system installations in Greece

    Microsoft Academic Search

    A. Michopoulos; K. T. Papakostas; N. Kyriakis

    2011-01-01

    The HVAC systems utilizing renewable energy sources are one of the main contributors towards the fossil fuel dependency reduction. Among these, the ground source heat pump systems, especially those based on vertical ground heat exchanger, are very attractive, due to their high efficiency.The size of the systems depends on the building (geometry, construction materials, orientation etc. but also usage and

  16. A simplified methodology for sizing ground coupled heat pump heat exchangers in cooling dominated climates 

    E-print Network

    Gonzalez, Jose Antonio

    1993-01-01

    results for the creation of base sizing charts. This simulation was based on discretizing the ground coil into elements and computing the soil temperature field using the analytical solution for a finite pipe with constant heat flux. Steady state heat... pump performance regressions were utilized by the computer simulation to simulate heat pulnp performance. For unit on-times of over ten minutes these steady state regressions provided a good approximation of actual behavior. Corrections for ground...

  17. Thermal performance of horizontal closed-loop ground-coupled heat pump systems using flowable-fill

    SciTech Connect

    Jones, W.V. Jr.; Beard, J.T.; Ribando, R.J. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical, Aerospace, and Nuclear Engineering; Wilhelm, B.K. [Virginia Power, Richmond, VA (United States). Energy Efficiency-Conservation Dept.

    1996-12-31

    This research evaluates the use of flowable-fill containing fly-ash in place of conventional dirt back-fill in horizontal closed-loop heat exchangers used in ground-source heat pump systems. A computer model was developed to simulate the transient heat transfer response in the fill material and native soil surrounding the heat exchangers. The model consists of a two-dimensional transient conduction model based on the finite-volume method. It simulates the energy extraction from the soil during the heating season and energy addition during the cooling season. A daily system load curve was used to approximate the daily heating and cooling load for a nominal two ton residential application in central Virginia. The computer model determined the thermal performance of various configurations when subjected to seasonal weather conditions. The variation in overall system performance was influenced by earth and fill thermal properties as well as geometric design parameters, such as trench length and depth. Ground-coupled heat pump systems with straight pipe and horizontal Slinky{trademark} configurations were installed at several residential demonstration-sites in Virginia. Temperature measurements were recorded at selected locations surrounding the ground heat exchanger, allowing evaluation of heat exchanger performance. Electrical measurements including heat pump compressor, air handler, and auxiliary electrical resistance energy were used to characterize overall system performance. Experimental measurements and model simulation studies have shown that encasing the ground-loop heat exchangers in flowable-fill rather than in earth backfill improves the overall thermal performance of ground source heat pump systems. Improved performance has been indicated by less extreme fill and soil temperatures and by lower annual electrical energy costs.

  18. Solar\\/performance goals for solar and ground-coupled heat pump systems

    Microsoft Academic Search

    J. W. Andrews

    1980-01-01

    Cost goals for combined solar\\/heat pump systems are developed. Three methods of analysis are used: simple payback, positive cash flow, and life cycle costing. The goals are parameterized on system energy efficiency, with the air-to-air heat pump as the conventional system which is used as a basis for comparison. Cost goals for nine systems are determined in three generic climates.

  19. A Review of Ground Coupled Heat Pump Models Used in Whole-Building Computer Simulation Programs 

    E-print Network

    Do, S. L.; Haberl, J. S.

    2010-01-01

    the last thirty years, a number of simulation models have been developed to calculate the performance of the ground heat exchanger (GHX). The several computer programs can evaluate the GCHP systems as a part of the whole-building energy simulation...

  20. Mitigation potential of horizontal ground coupled heat pumps for current and future climatic conditions: UK environmental modelling and monitoring studies

    NASA Astrophysics Data System (ADS)

    García González, Raquel; Verhoef, Anne; Vidale, Pier Luigi; Gan, Guohui; Wu, Yupeng; Hughes, Andrew; Mansour, Majdi; Blyth, Eleanor; Finch, Jon; Main, Bruce

    2010-05-01

    An increased uptake of alternative low or non-CO2 emitting energy sources is one of the key priorities for policy makers to mitigate the effects of environmental change. Relatively little work has been undertaken on the mitigation potential of Ground Coupled Heat Pumps (GCHPs) despite the fact that a GCHP could significantly reduce CO2 emissions from heating systems. It is predicted that under climate change the most probable scenario is for UK temperatures to increase and for winter rainfall to become more abundant; the latter is likely to cause a general rise in groundwater levels. Summer rainfall may reduce considerably, while vegetation type and density may change. Furthermore, recent studies underline the likelihood of an increase in the number of heat waves. Under such a scenario, GCHPs will increasingly be used for cooling as well as heating. These factors will affect long-term performance of horizontal GCHP systems and hence their economic viability and mitigation potential during their life span ( 50 years). The seasonal temperature differences encountered in soil are harnessed by GCHPs to provide heating in the winter and cooling in the summer. The performance of a GCHP system will depend on technical factors (heat exchanger (HE) type, length, depth, and spacing of pipes), but also it will be determined to a large extent by interactions between the below-ground parts of the system and the environment (atmospheric conditions, vegetation and soil characteristics). Depending on the balance between extraction and rejection of heat from and to the ground, the soil temperature in the neighbourhood of the HE may fall or rise. The GROMIT project (GROund coupled heat pumps MITigation potential), funded by the Natural Environment Research Council (UK), is a multi-disciplinary research project, in collaboration with EarthEnergy Ltd., which aims to quantify the CO2 mitigation potential of horizontal GCHPs. It considers changing environmental conditions and combines model predictions of soil moisture content and soil temperature with measurements at different GCHP locations over the UK. The combined effect of environment dynamics and horizontal GCHP technical properties on long-term GCHP performance will be assessed using a detailed land surface model (JULES: Joint UK Land Environment Simulator, Meteorological Office, UK) with additional equations embedded describing the interaction between GCHP heat exchangers and the surrounding soil. However, a number of key soil physical processes are currently not incorporated in JULES, such as groundwater flow, which, especially in lowland areas, can have an important effect on the heat flow between soil and HE. Furthermore, the interaction between HE and soil may also cause soil vapour and moisture fluxes. These will affect soil thermal conductivity and hence heat flow between the HE and the surrounding soil, which will in turn influence system performance. The project will address these issues. We propose to drive an improved version of JULES (with equations to simulate GCHP exchange embedded), with long-term gridded (1 km) atmospheric, soil and vegetation data (reflecting current and future environmental conditions) to reliably assess the mitigation potential of GCHPs over the entire domain of the UK, where uptake of GCHPs has been low traditionally. In this way we can identify areas that are most suitable for the installation of GCHPs. Only then recommendations can be made to local and regional governments, for example, on how to improve the mitigation potential in less suitable areas by adjusting GCHP configurations or design.

  1. Study on hybrid ground-coupled heat pump system for air-conditioning in hot-weather areas like Hong Kong

    Microsoft Academic Search

    Yi Man; Hongxing Yang; Jinggang Wang

    2010-01-01

    The ground-coupled heat pump (GCHP) system is becoming attractive for air-conditioning in some moderate-weather regions due to its high energy efficiency and reliable operation capability. However, when the technology is used in buildings where there is only cooling load in hot-weather areas like Hong Kong, the heat rejected into the ground by the GCHP systems will accumulate around the ground

  2. A techno-economic comparison of a direct expansion ground-source and a secondary loop ground-coupled heat pump system for cooling in a residential building

    Microsoft Academic Search

    Yonghui Guo; Guoqiang Zhang; Jin Zhou; Jiasheng Wu; Wei Shen

    This paper reports a techno-economic comparison between a direct expansion ground-source heat pump system (DX-GSHP) and a secondary loop ground-coupled heat pump system (SL-GCHP). For this purpose, a DX-GSHP and an SL-GCHP system are designed and installed in parallel for same space cooling load in a demonstrating building in Hunan province, China. The structures of the two systems are described.

  3. Development and Application of a Ground-Coupled Heat Pump Simulation Model for Residential Code-Compliance Simulation in Texas

    E-print Network

    Do, Sung Lok

    2014-04-18

    ) model for residential systems to be used with the DOE-2.1e simulation program. To accomplish this, this study investigated closed-loop ground heat exchanger (GHX) models, including horizontal, surface water, and vertical GHX models. This study selected...

  4. A short time step response factor model for vertical ground loop heat exchangers

    SciTech Connect

    Yavuzturk, C.; Spitler, J.D.

    1999-07-01

    The short-term behavior of ground-coupled heat pump systems is important for design of ground loop heat exchangers, energy analysis of ground source heat pump systems, and design of hybrid ground source systems. This paper describes the development of short time-step temperature response factors for vertical ground loop heat exchangers as used in ground-coupled heat pump systems. The short time-step response factors allow for a direct evaluation of system energy consumption and electrical demand in hourly or shorter time intervals. The development of the temperature response factors is based on an analytically validated, transient two-dimensional implicit finite volume model designed for the simulation of heat transfer over a vertical U-tube ground heat exchanger. The short time-step response factors are implemented as part of a component model for TRNSYS and an example application is provided based on an actual building.

  5. Thermal performance of horizontal closed-loop ground-coupled heat pump systems using flowable-fill

    Microsoft Academic Search

    Walter V. Jones; J. Taylor Beard; Robert J. Ribando; Barry K. Wilhelm

    1996-01-01

    This research evaluates the use of flowable-fill containing fly-ash in place of conventional dirt back-fill in horizontal closed-loop heat exchangers used in ground-source heat pump systems. A computer model was developed to simulate the transient heat transfer response in the fill material and native soil surrounding the heat exchangers. The model consists of a two-dimensional transient conduction model based on

  6. EnergyPlus vs DOE-2: The Effect of Ground Coupling on Heating and Cooling Energy Consumption of a Slab-On-Grade Code House in a Cold Climate

    E-print Network

    Andolsun, S.; Culp, C.; Haberl, J.

    -on-grade constructions. This paper extends the previous comparative work by comparing EnergyPlus and DOE-2.1e results for GCHT based on a slab-on- grade code house in a cold climate. Three GCHT models were used in the study. These models were Winkelmann?s (2002...) model in DOE-2.1e, Winkelmann?s model in EnergyPlus and EnergyPlus with its GCHT calculator utility, Slab. INTRODUCTION Ground-coupled heat transfer (GCHT) through concrete floor slabs is a significant component of the total load for heating...

  7. The Numerical Simulation and Experiment Study on the Coupled Thermal Conduction and Groundwater Advection Heat Transfer Process under the Intermittent Operation of the Ground-Coupled Heat Pump System

    Microsoft Academic Search

    Sufen Li; Yan Shang

    2010-01-01

    The three-dimension coupled thermal conduction and groundwater advection unsteady state heat transfer model in this paper is developed according to the heat-transfer process between the vertical U tube underground and its ambient soil. The feasibility of this model is verified by intermittent experiment of ground source heat pump in winter. In the model, boundary layer is replaced by velocity equation

  8. Mixed convection heat transfer and flow in vertically heated channels

    Microsoft Academic Search

    C. Gau; Win Aung; K. A. Yih

    1990-01-01

    Experiments are performed to study and understand buoyancy effect on the heat transfer process and flow in a finite vertical, rectangular channel. One wall is insulated and the opposite wall is heated uniformly. Uniform air flow is made to enter the channel. Both the case for buoyancy assisted flow and the case for opposed flow are studied. The mean velocity

  9. Mixed convection heat transfer and flow in vertically heated channels

    NASA Astrophysics Data System (ADS)

    Gau, C.; Aung, Win; Yih, K. A.

    1990-06-01

    Experiments are performed to study and understand buoyancy effect on the heat transfer process and flow in a finite vertical, rectangular channel. One wall is insulated and the opposite wall is heated uniformly. Uniform air flow is made to enter the channel. Both the case for buoyancy assisted flow and the case for opposed flow are studied. The mean velocity is controlled at values that the channel flow is either laminar or turbulent when the plate is not heated. Both flow visualization and temperature fluctuation measurements are conducted and used to provide information on flow structure. Flow reversal occurs initially downstream and moves periodically upstream as the buoyancy parameters Gr/Re increases, which destabilizes the flow structure and enhances the heat transfer process in the range it transverses. The effect of buoyancy force on the local and averaged Nusselt number over the heated plate is studied. The buoyancy parameter studied ranges from 800 to 60,000.

  10. Field and Laboratory Study of a Ground-Coupled Water Source Heat Pump with an Integral Enthalpy Exchange System for Classrooms

    E-print Network

    Domitrovic, R.; Hayzen, G. J.; Johnson, W. S.; Chen, F. C.

    2002-01-01

    water-source heat pump, coupled with a geothermal water loop and incorporating a forced fresh-air enthalpy exchange system was installed in a typical middle school classroom in Oak Ridge, Tennessee. This project is a joint effort among Oak Ridge School...

  11. Heating system with vapour compressor heat pump and vertical U-tube ground heat exchanger

    NASA Astrophysics Data System (ADS)

    Hanuszkiewicz-Drapa?a, Ma?gorzata; Sk?adzie?, Jan

    2010-10-01

    In the paper a heating system with a vapour compressor heat pump and vertical U-tube ground heat exchanger for small residential house is considered. A mathematical model of the system: heated object - vapour compressor heat pump - ground heat exchanger is presented shortly. The system investigated is equipped, apart from the heat pump, with the additional conventional source of heat. The processes taking place in the analyzed system are of unsteady character. The model consists of three elements; the first containing the calculation model of the space to be heated, the second - the vertical U-tube ground heat exchanger with the adjoining area of the ground. The equations for the elements of vapour compressor heat pump form the third element of the general model. The period of one heating season is taken into consideration. The results of calculations for two variants of the ground heat exchanger are presented and compared. These results concern variable in time parameters at particular points of the system and energy consumption during the heating season. This paper presents the mutual influence of the ground heat exchanger subsystem, elements of vapour compressor heat pump and heated space.

  12. The vertical structure of ocean heat transport G. Boccaletti,1

    E-print Network

    Marshall, John

    global ocean heat transport can be deduced from estimates of air-sea fluxes [Trenberth and Caron, 2001The vertical structure of ocean heat transport G. Boccaletti,1 R. Ferrari,1 A. Adcroft,2 D is through its poleward heat transport: about 1.5 PW or more than 30% of that accomplished by the ocean

  13. Correlation to Predict the Maximum Heat Flux of a Vertical Closed-Loop Pulsating Heat Pipe

    Microsoft Academic Search

    Niti Kammuang-Lue; Phrut Sakulchangsatjatai; Pradit Terdtoon; D. Joseph Mook

    2009-01-01

    The objective of this study is to experimentally investigate the effect of various parameters on the maximum heat flux of a vertical closed-loop pulsating heat pipe (CLPHP) and the inside phenomena that cause maximum heat flux to occur. A correlation to predict the maximum heat flux using the obtained results was also established. Quantitative and qualitative experiments were conducted and

  14. Heat-transfer mechanism of liquid film flow in a vertical, finely grooved heating surface

    Microsoft Academic Search

    M. Ouchi; M. Izumi; N. Yamakawa; Y. Takamori; T. Takeyama

    1991-01-01

    The heating surface structure characteristic of a vertical tube is emphasized in order to obtain nucleate boiling stability in the liquid film and to avoid the splitting of the liquid film into rivulets. Horizontally, vertically, and obliquely grooved surfaces were used in this paper with a constant liquid flow rate and isothermal surface conditions. The overall, as well as local,

  15. Development of spiral heat source model for novel pile ground heat exchangers

    Microsoft Academic Search

    Yi Man; Hongxing Yang; Nairen Diao; Ping Cui; Lin Lu; Zhaohong Fang

    2011-01-01

    The extensive application of ground coupled heat pump system (GCHP) is restricted by the installation cost of conventional borehole ground heat exchangers (GHE), which is not only expensive but also requires additional ground area. The idea of combining the GHE with building foundation piles, i.e., the “energy pile,” has arisen in recent years. The novel pile GHEs consisting of vertical

  16. An experiment on thermosyphon boiling in uniformly heated vertical tube and asymmetrically heated vertical channel

    Microsoft Academic Search

    Jin-Seok Jeon; Jung Hee Na; Hong Chul Park; Ho-Young Kwak

    2001-01-01

    Continuing efforts to achieve increased circuit performance in electronic package have resulted in higher power density at\\u000a chip and module level. As a result, the thermal management of electronic package has been important in maintaining or improving\\u000a the reliability of the component. An experimental investigation of thermosyphonic boiling in vertical tube and channel made\\u000a by two parallel rectangular plates was

  17. Convective heat transfer around vertical jet fires: an experimental study.

    PubMed

    Kozanoglu, Bulent; Zárate, Luis; Gómez-Mares, Mercedes; Casal, Joaquim

    2011-12-15

    The convection heat transfer phenomenon in vertical jet fires was experimentally analyzed. In these experiments, turbulent propane flames were generated in subsonic as well as sonic regimes. The experimental data demonstrated that the rate of convection heat transfer increases by increasing the length of the flame. Assuming the solid flame model, the convection heat transfer coefficient was calculated. Two equations in terms of adimensional numbers were developed. It was found out that the Nusselt number attains greater values for higher values of the Rayleigh and Reynolds numbers. On the other hand, the Froude number was analyzed only for the subsonic flames where the Nusselt number grows by this number and the diameter of the orifice. PMID:21962859

  18. Natural convection in symmetrically heated vertical parallel plates with discrete heat sources

    SciTech Connect

    Manca, O. [Seconda Univ. degli studi di Napoli, Aversa (Italy). Dipt. di Ingegneria Aerospaziale; Nardini, S.; Naso, V. [Univ. degli studi Federico II, Napoli (Italy)

    1996-12-31

    Laminar air natural convection in a symmetrically heated vertical channel with uniform flush-mounted discrete heat sources has been experimentally investigated. The effects of heated strips location and of their number are pointed out in terms of the maximum wall temperatures. A flow visualization in the entrance region of the channel was carried out and air temperatures and velocities in two cross sections have been measured. Dimensionless local heat transfer coefficients have been evaluated and monomial correlations among relevant parameters have bee derived in the local Rayleigh number range 10--10{sup 6}. Channel Nusselt number has been correlated in a polynomial form in terms of channel Rayleigh number.

  19. Measured performance of a solar-ground source heat pump system with vertical double spiral coil ground heat exchanger

    Microsoft Academic Search

    Yuehong Bi; Linger Chen; Chih Wu

    2001-01-01

    The experimental study was performed for a solar-ground source heat pump (SGSHP) system with a vertical double spiral coil (VDSC) ground heat exchanger (GHX). The heating mode of the SGSHP system is alternated between a solar energy source heat pump (SSHP) and a ground source heat pump (GSHP) using a low grade energy utilisation system built by the authors. The

  20. Efficiency of vertical geothermal heat exchangers in the ground source heat pump system

    NASA Astrophysics Data System (ADS)

    Zeng, Heyi; Diao, Nairen; Fang, Zhaohong

    2003-02-01

    Taking the fluid temperature distribution along the borehole depth into account, a new quasi-three-dimensional model for vertical ground heat exchangers has been established, which provides a better understanding of the heat transfer processes in the geothermal heat exchangers. On this basis the efficiency of the borehole has been defined and its analytical expression derived. Comparison with the previous two-dimensional model shows that the quasi-three-dimensional model is more rational and more accurate to depict the practical feature of the conduction of geothermal heat exchanger, and the efficiency notion can be easily used to determine the inlet and outlet temperature of the circulating fluid inside the heat exchanger.

  1. High Rayleigh number laminar natural convection in an asymmetrically heated vertical channel

    Microsoft Academic Search

    B. W. Webb; D. P. Hill

    1989-01-01

    Experiments have been performed to determine local heat transfer data for the natural convective flow of air between vertical parallel plates heated asymmetrically. A uniform heat flux was imposed along one heated wall, with the opposing wall of the channel being thermally insulated. Local temperature data along both walls were collected for a wide range of heating rates and channel

  2. Experimental Studies of the Enhanced Heat Transfer from a Heating Vertical Flat Plate by Ionic Wind

    NASA Astrophysics Data System (ADS)

    Yue, Yonggang; Hou, Junping; Ai, Zhongliang; Yang, Lanjun; Zhang, Qiaogen

    2006-11-01

    The effects of the ionic wind on the heat transfer rate from a heated vertical flat plate are described. The ionic wind is induced by three different types of discharge, corona discharge, dielectric barrier discharge (DBD) and dc glow discharge. The heat transfer coefficients for the heated copper plate under free convection conditions with and without an ionic wind are obtained by measuring the temperature and the heating power of the copper plate. It has been proved that the convective heat transfer coefficients increase by several times with the help of the ionic wind. With the ionic wind induced by a uniform dc glow discharge, the heat transfer coefficient of the heated copper plate is highly enhanced compared with those induced by a corona discharge or DBD. With the use of DBD, the breakdown voltage is increased significantly, which is helpful in avoiding a breakdown when heat transfer is enhanced by the ionic wind. In addition, it makes the application of the ionic wind much safer.

  3. Heat transfer augmentation of mixed convection through vortex shedding from an inclined plate in a vertical channel containing heated blocks

    SciTech Connect

    Wu, H.W.; Perng, S.W. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Naval Architecture and Marine Engineering

    1998-02-06

    A numerical analysis is made of the unsteady flow and heat transfer characteristics of mixed convection in a vertical block-heated channel with and without installing an inclined plate above an upstream block. Parameter studies including the inclined plate angle, Reynolds number (ranging from 260 to 530), and Grashof number (in the range of 0--3,200,000) on heat transfer performance have been explored in detail. The results show that the installation of an inclined plate in the vertical block-heated channel can effectively augment the blocks` heat transfer performance in the channel. This can be applied to heat exchangers.

  4. Effect of horizontal heat and fluid flow on the vertical temperature distribution in a semiconfining layer

    USGS Publications Warehouse

    Lu, N.; Ge, S.

    1996-01-01

    By including the constant flow of heat and fluid in the horizontal direction, we develop an analytical solution for the vertical temperature distribution within the semiconfining layer of a typical aquifer system. The solution is an extension of the previous one-dimensional theory by Bredehoeft and Papadopulos [1965]. It provides a quantitative tool for analyzing the uncertainty of the horizontal heat and fluid flow. The analytical results demonstrate that horizontal flow of heat and fluid, if at values much smaller than those of the vertical, has a negligible effect on the vertical temperature distribution but becomes significant when it is comparable to the vertical.

  5. Thermal and fluid dynamic behavior of symmetrically heated vertical channels with auxiliary plate

    Microsoft Academic Search

    Assunta Andreozzi; Oronzio Manca

    2001-01-01

    Air natural convection in vertical channel configurations is strongly attractive in thermal design and control of devices. This is mainly due to its simplicity, no maintenance costs and reliability. This paper examines air natural convection in vertical channels with an auxiliary plate along the centerline. The channel is symmetrically heated and the walls are at uniform heat flux, whereas the

  6. Heat exchanger sizing for vertical closed-loop ground-source heat pumps

    SciTech Connect

    Cane, R.L.D.; Clemes, S.B.; Morrison, A. [Caneta Research, Inc., Mississauga, Ontario (Canada); Hughes, P.J. [Oak Ridge National Lab., TN (United States)

    1995-11-01

    A building energy simulation program has been used in conjunction with a ground heat exchanger sizing algorithm to develop general guidelines on how to size vertical ground heat exchangers for closed-loop ground-source heat pump systems in large buildings. The analysis considered three commercial building types of varying size with different internal loads and heat pump efficiencies. Each building variation was simulated in seven cities, three in the United States and four in Canada. The ground heat exchanger sizing algorithm has been previously validated against actual system data. The analysis results showed a strong correlation between heat exchanger length required and annual energy rejected to the ground, if the building was cooling-dominated, or annual energy extracted from the ground, if the building was heating-dominated. The resulting sizing guidelines recommend hour-by-hour energy analysis to determine the energy extracted from and rejected to the building water loop. Using this information the designer will have available easy-to-use, accurate sizing guidelines that should result in more economical installations than those based on previous ``rule of thumb`` guidelines.

  7. Heat exchanger sizing for vertical closed-loop ground-source heat pumps

    SciTech Connect

    Cane, R.L.D.; Clemes, S.B.; Morrison, A. [Caneta Research, Inc., Mississauga, Ontario (Canada); Hughes, P.J. [Oak Ridge National Lab., TN (United States)

    1995-12-31

    A building energy simulation program has been used in conjunction with a ground heat exchanger sizing algorithm to develop general guidelines on how to size vertical ground heat exchangers for closed-loop ground-source heat pump systems in large buildings. The analysis considered three commercial building types of varying size with different internal loads and heat pump efficiencies. Each building variation was simulated in seven cities, three in the US and four in Canada. The ground heat exchanger sizing algorithm has been previously validated against actual system data. The analysis results showed a strong correlation between heat exchanger length required and annual energy rejected to the ground, if the building was cooling-dominated, or annual energy extracted from the ground, if the building was heating-dominated. The resulting sizing guidelines recommend hour-by-hour energy analysis to determine the energy extracted from and rejected to the building water loop. Using this information the designer will have available easy-to-use, accurate sizing guidelines that should result in more economical installations than those based on previous ``rule of thumb`` guidelines.

  8. Efficient Energy Supply from Ground Coupled Heat Transfer Source

    Microsoft Academic Search

    Maurizio Carlini; Sonia Castellucci

    2010-01-01

    \\u000a The increasing demands of Energy for industrial production and urban facilities, asks for new strategies for Energy sources.\\u000a In recent years an important problem is to have some energy storage, energy production and energy consumption which fulfill\\u000a some environment friendly expectations. Much more attention has been recently devoted to renewable energies [1]. Among them\\u000a energy production from geothermal sources has

  9. Retrieval Algorithms for Estimating the Vertical Profiles of Latent Heat Release: Their Applications for TRMM

    Microsoft Academic Search

    Wei-Kuo Tao; S. Lang; Joanne Simpson; Robert F. Adler

    1993-01-01

    The latent heat release is a consequence of phase change (vapor, liquid and solid) of water. An algorithm has been developed (Tao et al., 1990) to estimate the latent heating of cloud systems as a function of their vertical hydrometeor profiles (termed a hydrometeor\\/heating algorithm). The derivation as well as the validation of the algorithm was based on results of

  10. Experimental study of vertical ground-source heat pump performance evaluation for cold climate in Turkey

    Microsoft Academic Search

    Omer Ozyurt; Dundar Arif Ekinci

    2011-01-01

    Heat pump systems are recognized to be outstanding heating, cooling and water heating systems. They provide high levels of comfort as well as offering significant reductions in electrical energy use. In addition, they have very low levels of maintenance requirements and are environmentally attractive. The purpose of this study is to evaluate the experimentally performance and energy analysis of vertical

  11. Assessing the Variability and Accuracy of Vertical Profiles of Heating and Vertical Motion in the Tropical Eastern Pacific

    NASA Astrophysics Data System (ADS)

    White, K. C.; Schumacher, C.

    2014-12-01

    Reanalyses are often used to describe the state of the atmosphere over the tropical Eastern Pacific (EP) because of the lack of in situ observations. Vertical profiles of vertical motion, which can be used as a proxy for latent heating profiles, have been shown to have large variability between reanalyses in the EP intertropical convergence zone (ITCZ), as well as a bottom heavy shape that contrasts with the top-heavy profile in the Western Pacific (WP) warm pool. At the same time, satellite-derived stratiform rain fractions are higher in convectively active portions of the EP than the WP, suggesting that a higher peak in latent heating (and thus vertical motion) should be seen in the EP. While the EP sees many more shallow precipitation systems than the WP, deep convection associated with synoptic waves still regularly occurs in the EP. The low-level peak in reanalysis vertical motion persists in the EP during El Niño, when precipitation systems become very similar to those in the WP. Additionally, comparison studies have shown a more top-heavy profile of heating derived from satellite retrieval algorithms than from reanalysis datasets, reinforcing the discrepancy. The accuracy of vertical motion and heating profiles in the EP is important due to their relationship to large-scale circulations such as the Walker and Hadley cells, as well as the shallow meridional circulation that has been observed and modeled in the EP over the last decade and a half. Some implications for climate sensitivity have also been drawn from reanalysis vertical motion profiles in the EP, adding to the gravity of this issue. In order to determine why the variability in EP vertical motion and heating profiles is so large, as well as whether the bottom heavy profiles in reanalyses are accurate, we analyze and show results from a comparison of eight reanalysis datasets to ship borne radar observations from the Tropical Eastern Pacific Process Study (TEPPS) and satellite data from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and the cloud profiling radar aboard CloudSat.

  12. Stratiform Precipitation, Vertical Heating Profiles, and the Madden Julian Oscillation

    Microsoft Academic Search

    Jialin Lin; Brian Mapes; Minghua Zhang; Matthew Newman

    2004-01-01

    ABSTRACT The observed profile of heating through the troposphere in the Madden?Julian oscillation (MJO) is found to be very top heavy: more so than seasonal-mean heating and systematically more,so than all of the seven models for which intraseasonal heating anomaly profiles have been published. Consistently, the Tropical Rainfall Mea- suring Mission (TRMM) precipitation radar shows that stratiform precipitation (known to

  13. Application of Hourly Simulation in Designing Vertical U-Pipe Underground Heat Exchanger of Ground Source Heat Pump System

    Microsoft Academic Search

    Hua Su; Xungen Shi

    2010-01-01

    Design of underground heat exchanger is crucial to application of ground source heat pump system. This paper presents the method and self-developed program for designing vertical U-pipe underground heat exchanger using numerical simulation. The program's accuracy was validated by comparison of outlet temperature between field test and simulation: the biases are not more than 1 centi-degree in most cases. This

  14. Method and apparatus for determining vertical heat flux of geothermal field

    DOEpatents

    Poppendiek, Heinz F. (LaJolla, CA)

    1982-01-01

    A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

  15. Maximal Heat Transfer Density in Vertical Morphing Channels with Natural Convection

    Microsoft Academic Search

    A. K. Da Silva; A. Bejan; S. Lorente

    2004-01-01

    In this article we show numerically that the entire flow geometry of a vertical diverging or converging channel with laminar natural convection can be optimized for maximal heat transfer rate density (total heat transfer rate per unit of flow system volume). The geometry is free to change in three ways: (1) the spacing between the walls, (2) the distribution of

  16. STUDY ON TEMPERATURE FIELD ROUND VERTICAL BURIED PIPE OF GROUND SOURCE HEAT PUMP IN INTERMITTENT OPERATION

    Microsoft Academic Search

    H. Songtao; T. Yu; W. Gang; S. Zhigang

    Heat transfer between soil and cooling water in buried pipes is presented, thus ground source heat pump can realize the transfer from low-grade energy to high-grade energy. We tested Water temperature and flow rate of the buried pipe of Ground source heat pump system under intermittent operation condition in Qingdao, temperature field of vertical buried double-U pipes is analyzed by

  17. Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

    NASA Astrophysics Data System (ADS)

    Bieli?ski, Henryk; Mikielewicz, Jaros?aw

    2010-10-01

    In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

  18. Experimental Investigation of Free-Convection Heat Transfer in Vertical Tube at Large Grashof Numbers

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Diaguila, A J

    1955-01-01

    Report presents the results of an investigation conducted to study free-convection heat transfer in a stationary vertical tube closed at the bottom. The walls of the tube were heated, and heated air in the tube was continuously replaced by fresh cool air at the top. The tube was designed to provide a gravitational field with Grashof numbers of a magnitude comparable with those generated by the centrifugal field in rotating-blade coolant passages (10(8) to 10(13)). Local heat-transfer coefficients in the turbulent-flow range and the temperature field within the fluid were obtained.

  19. Experimental study on condensation heat transfer characteristics of R410A in short vertical tubes

    NASA Astrophysics Data System (ADS)

    Xu, Wenyun; Jia, Li; Tan, Zetao

    2015-06-01

    An experimental study on condensation heat transfer of R410A in short vertical tubes (8.02 mm ID and 10.7mm ID) was presented. Experiments were performed in eight short copper tubes length varied from 300mm to 600mm at mass fluxes range of 58-246 kg m-2s-1 and saturation temperature of 38°C. Effects of mass flux, tube length on condensation heat transfer coefficient were investigated. The distribution of temperature, thickness of condensate film and local condensation heat transfer coefficient along the tube were also analyzed. It is indicated that the entrance effect played an important role in condensation heat transfer of vertical tube, and the influence of entrance effect on average condensation heat transfer coefficients will weaken with the length of tube in the experimental condensation. The experimental results were compared with four well known correlations available in literatures, and the Chen correlation shows good agreement with the experimental data but with ±40% deviation. A new modified condensation heat transfer correlation with 12.7% mean deviation was developed to predict the condensation heat transfer coefficients in short vertical tube based on the experimental data.

  20. Limitations of Using Uniform Heat Flux Assumptions in Sizing Vertical Borehole Heat Exchanger Fields

    E-print Network

    of ground heat exchangers (GHE) used with ground source heat pump (GSHP) systems. These models can account approach with a parametric study. Keywords - Ground Source Heat Pumps; Borehole Heat Exchangers; Finite Line Source Theory; g-functions 1. Introduction Ground source heat pump (GSHP) systems are a widely

  1. Comparison of turbulence models for the natural convection boundary layer along a heated vertical plate

    Microsoft Academic Search

    R. A. W. M. Henkes; C. J. Hoogendoorn

    1989-01-01

    A numerical code for solving the boundary-layer equations is used to evaluate the performance of various turbulence models for the natural convection boundary layer along a heated vertical plate. The Cebeci-Smith (1974) model yields wall-heat transfer and turbulent viscosity values that are lower than the experimental values, while the standard k-epsilon model with wall functions for k and epsilon yields

  2. ANN and ANFIS models for performance evaluation of a vertical ground source heat pump system

    Microsoft Academic Search

    Hikmet Esen; Mustafa Inalli

    2010-01-01

    The aim of this study is to demonstrate the comparison of an artificial neural network (ANN) and an adaptive neuro-fuzzy inference system (ANFIS) for the prediction performance of a vertical ground source heat pump (VGSHP) system. The VGSHP system using R-22 as refrigerant has a three single U-tube ground heat exchanger (GHE) made of polyethylene pipe with a 40mm outside

  3. Heat-transfer characteristics of climbing film evaporation in a vertical tube

    SciTech Connect

    Yang, Luopeng; Chen, Xue; Shen, Shengqiang [Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024 (China)

    2010-09-15

    Heat-transfer characteristics of climbing film evaporation were experimentally investigated on a vertical climbing film evaporator heated by tube-outside hot water. The experimental setup was designed for determining the effect of the height of feed water inside a vertical tube and the range of temperature difference on local heat transfer coefficient inside a vertical tube (h{sub i}). In this setup, the height of feed water was successfully controlled and the polypropylene shell effectively impedes the heat loss to the ground. The results indicated that a reduction in the height of feed water contributed to a significant increase in h{sub i} if no dry patches around the wall of the heated tube appeared inside the tube. The height ratio of feed water R{sub h} = 0.3 was proposed as the optimal one as dry patches destroyed the continuous climbing film when R{sub h} is under 0.3. It was found that the minimum temperature difference driving climbing film evaporation is suggested as 5 C due to a sharp reduction in h{sub i} for temperature difference below 5 C. The experiment also showed that h{sub i} increased with an increase in temperature difference, which proved the superiority of climbing film evaporation in utilizing low-grade surplus heating source due to its wide range of driving temperature difference. The experimental results were compared with the previous literature and demonstrated a satisfactory agreement. (author)

  4. Vertical heat flux and lateral mass transport in nonlinear internal waves

    E-print Network

    speed (c). Therefore, horizontal advection is important, and NLIWs transport mass as well as energy was a dominant term in the vertical heat balance, during the observation period, and that NLIWs transported fluid and Observations [5] NLIWs were tracked across New Jersey's shelf, using shipboard acoustics (120 kHz echosounder

  5. Non-linear dynamics and pattern formation in a vertical fluid layer heated from the side

    Microsoft Academic Search

    Dmitry A Bratsun; Alexej V Zyuzgin; Gennady F Putin

    2003-01-01

    We study both experimentally and numerically the convective flow in a tall vertical slot with differently heated walls. The flow is investigated for the fluid with the Prandtl number Pr=26, which is large enough to ensure the traveling waves as primary instability and small enough to prevent boundary layer convection. The flow evolution is determined on the base of the

  6. Techno-economic and spatial analysis of vertical ground source heat pump systems in Germany

    Microsoft Academic Search

    Philipp Blum; Gisela Campillo; Thomas Kölbel

    2011-01-01

    The objective of the current study was to assess the technical and economic factors that influence the design and performance of vertical GSHP (ground source heat pump) systems and to evaluate the spatial correlation that these factors have with geographic components such as geology and climatic conditions. The data from more than 1100 individual GSHP systems were analysed. The average

  7. Critical heat flux of water in vertical round tubes at low pressure and low flow conditions

    Microsoft Academic Search

    Hong Chae Kim; Won-Pil Baek; Soon Heung Chang

    2000-01-01

    An experimental study on critical heat flux (CHF) has been performed for water flow in vertical round tubes under low pressure and low flow (LPLF) conditions to provide a systematic data base and to investigate parametric trends. Totally 513 experimental data have been obtained with Inconel-625 tube test sections in the following conditions: diameter of 6, 8, 10 and 12

  8. Heat transfer analysis in a two-side heated smooth square vertical channel with adverse and favorable mixed convection

    SciTech Connect

    Dutta, S.; Zhang, X.; Khan, J.A.; Bell, D.

    1997-07-01

    Experimental heat transfer measurements and analysis for mixed convection in a vertical square channel are presented. The flow direction is changed with respect to the earth's gravity field by selectively opening and closing the flow control valves. Desired flow directions are selected such that buoyancy assists or opposes the bulk flow direction pressure gradient. The heating condition is asymmetric. Most previous experiments used symmetrically heated circular tubes. Present configuration shows significant increase in the Nusselt number in both assisted and opposed flow conditions. In general, opposed flow shows higher heat transfer coefficients. Unlike symmetric heating conditions, Nusselt number ratio is observed to be increasing with increasing Gr/Re or Gr/Re{sup 2} ratios for both assisted and opposed flow conditions.

  9. Empirical models of the eddy heat flux and vertical shear on short time scales

    NASA Technical Reports Server (NTRS)

    Ghan, S. J.

    1984-01-01

    An intimate relation exists between the vertical shear and the horizontal eddy heat flux within the atmosphere. In the present investigation empirical means are employed to provide clues concerning the relationship between the shear and eddy heat flux. In particular, linear regression models are applied to individual and joint time series of the shear and eddy heat flux. These discrete models are used as a basis to infer continuous models. A description is provided of the observed relationship between the flux and the shear, taking into account means, standard deviations, and lag correction functions.

  10. Boiling heat transfer in a vertical microchannel: Local estimation during flow boiling with a non intrusive method

    E-print Network

    are conducted with HFE-7100 as this fluid has a low boiling temperature at the cabin pressure of the A300Boiling heat transfer in a vertical microchannel: Local estimation during flow boiling with a non the results of experimental and numerical studies concerning boiling heat transfer inside vertical

  11. Experimental research on heat transfer of natural convection in vertical rectangular channels with large aspect ratio

    SciTech Connect

    Lu, Qing; Qiu, Suizheng; Su, Guanghui [State Key Laboratory of Multi Phase Flow in Power Engineering, Xi'an JIaotong University, Xi'an, Shaanxi 710049 (China); School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Tian, Wenxi; Ye, Zhonghao [School of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

    2010-01-15

    This work presents the experimental research on the steady laminar natural convection heat transfer of air in three vertical thin rectangular channels with different gap clearance. The much higher ratio of width to gap clearance (60-24) and the ratio of length to gap clearance (800-320) make the rectangular channels similar with the coolant flow passage in plate type fuel reactors. The vertical rectangular channels were composed of two stainless steal plates and were heated by electrical heating rods. The wall temperatures were detected with the K-type thermocouples which were inserted into the blind holes drilled in the steal plates. Also the air temperatures at the inlet and outlet of the channel were detected. The wall heat fluxes added to the air flow were calculated by the Fourier heat conduction law. The heat transfer characteristics were analyzed, and the average Nusselt numbers in all the three channels could be well correlated with the Rayleigh number or the modified Rayleigh number in a uniform correlation. Furthermore, the maximum wall temperatures were investigated, which is a key parameter for the fuel's integrity during some accidents. It was found that even the wall heat flux was up to 1500 W/m{sup 2}, the maximum wall temperature was lower than 350 C. All this work is valuable for the plate type reactor's design and safety analysis. (author)

  12. Constructal multi-scale package of vertical channels with natural convection and maximal heat transfer density. CONSTRUCTAL DESIGN: THE GENERATION OF MULTI-SCALE HEAT

    E-print Network

    Kihm, IconKenneth David

    transfer density. CONSTRUCTAL DESIGN: THE GENERATION OF MULTI-SCALE HEAT AND FLUID FLOW STRUCTURES-scale structures in natural convection with the objective of maximizing the heat transfer density, or the heat transfer rate per unit of volume§ . The flow volume is filled with vertical equidistant heated blades

  13. Experimental study on flow boiling heat transfer of LNG in a vertical smooth tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-10-01

    An experimental apparatus is set up in this work to study the upward flow boiling heat transfer characteristics of LNG (liquefied natural gas) in vertical smooth tubes with inner diameters of 8 mm and 14 mm. The experiments were performed at various inlet pressures from 0.3 to 0.7 MPa. The results were obtained over the mass flux range from 16 to 200 kg m-2 s-1 and heat fluxes ranging from 8.0 to 32 kW m-2. The influences of quality, heat flux and mass flux, tube diameter on the heat transfer characteristic are examined and discussed. The comparisons of the experimental heat transfer coefficients with the predicted values from the existing correlations are analyzed. The correlation by Zou et al. [16] shows the best accuracy with the RMS deviation of 31.7% in comparison with the experimental data.

  14. Simultaneous heat and mass transfer inside a vertical channel in evaporating a heated falling glycols liquid film

    NASA Astrophysics Data System (ADS)

    Nait Alla, Abderrahman; Feddaoui, M'barek; Meftah, Hicham

    2015-03-01

    The interactive effects of heat and mass transfer in the evaporation of ethylene and propylene glycol flowing as falling films on vertical channel was investigated. The liquid film falls along a left plate which is externally subjected to a uniform heat flux while the right plate is the dry wall and is kept thermally insulated. The model solves the coupled governing equations in both phases together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by Tridiagonal Matrix Algorithm. The influence of the inlet liquid flow, Reynolds number in the gas flow and the wall heat flux on the intensity of heat and mass transfers are examined. A comparison between the results obtained for studied glycols and water in the same conditions is made. The results indicate that water evaporates in more intense way in comparison to glycols and the increase of gas flow rate tends to improve slightly the evaporation.

  15. Effects of confining walls on heat transfer from a vertical array of isothermal horizontal elliptic cylinders

    SciTech Connect

    Yousefi, T.; Paknezhad, M. [Mechanical Engineering Department, Razi University, Kermanshah, Tehran 11365-4563 (Iran); Ashjaee, M.; Yazdani, S. [School of Mechanical Engineering, University of Tehran, Tehran 11365-4563 (Iran)

    2009-09-15

    Steady state two-dimensional natural convection heat transfer from the vertical array of five horizontal isothermal elliptic cylinders with vertical major axis which confined between two adiabatic walls has been studied experimentally. Experiments were carried out using a Mach-Zehnder interferometer. The Rayleigh number based on cylinder major axis was in the range 10{sup 3}{<=}Ra{<=}2.5 x 10{sup 3}, and dimensionless wall spacing 1.5{<=} t/b{<=}9 and infinity. The effect of wall spacing and Rayleigh number on the heat transfer from the individual cylinder and the array were investigated. Experiments are performed for ratio wall spacing to major diameter t/b = 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9 and infinity. A correlation based on the experimental data for the average Nusselt number of the array as a function of Ra and t/b is presented in the aforementioned ranges. A relation has been derived for optimum wall spacing at which the Nusselt number of the array attains its maximum value. At optimum wall spacing, approximately 10% increase in the heat transfer from the confined array of elliptic cylinders has been observed as compared to the unconfined case. Also, a heat transfer correlation has been proposed for a single elliptic cylinder with vertical major axis and has been compared with earlier works. (author)

  16. Vertical heat transfer in the Arctic Ocean: The role of double-diffusive mixing

    NASA Astrophysics Data System (ADS)

    Sirevaag, Anders; Fer, Ilker

    2012-07-01

    Microstructure profiles collected in the central Amundsen Basin are analyzed in order to quantify the role of double-diffusive mixing for vertical heat transfer from the Atlantic layer. In the profiles, a persistent, but laterally incoherent thermohaline staircase structure is identified in the 200-260 m depth range. The staircase contains homogeneous layers with average height of 1.3 m and thin, high-gradient interfaces with average temperature and salinity jumps of about 0.065°C and 0.015, respectively. When inferred from a commonly used diffusive convection parameterization, the average vertical heat flux within the staircase is 0.6 W m-2. This is one order of magnitude larger than the molecular diffusion alone and of the same order as the overall heat loss from the Atlantic layer in the deep basins of the Arctic Ocean. The parameterization is evaluated using observed turbulent heat fluxes and is found to overestimate diffusive convective fluxes with up to an order of magnitude, especially for weak thermal forcing (small temperature jumps in staircase). Staircases coexist with thermohaline intrusions in the vertical temperature and salinity profiles. Lomonosov Ridge is identified as a potential region for formation of intrusions. It is found that salt fingering is the dominant process during intrusion growth whereas diffusive convection is the dominant process in maintaining the intrusions at steady state in the deep basins.

  17. Heat transfer to water from a vertical tube bundle under natural-circulation conditions. [PWR; BWR

    SciTech Connect

    Gruszczynski, M.J.; Viskanta, R.

    1983-01-01

    The natural circulation heat transfer data for longitudinal flow of water outside a vertical rod bundle are needed for developing correlations which can be used in best estimate computer codes to model thermal-hydraulic behavior of nuclear reactor cores under accident or shutdown conditions. The heat transfer coefficient between the fuel rod surface and the coolant is the key parameter required to predict the fuel temperature. Because of the absence of the required heat transfer coefficient data base under natural circulation conditions, experiments have been performed in a natural circulation loop. A seven-tube bundle having a pitch-to-diameter ratio of 1.25 was used as a test heat exchanger. A circulating flow was established in the loop, because of buoyancy differences between its two vertical legs. Steady-state and transient heat transfer measurements have been made over as wide a range of thermal conditions as possible with the system. Steady state heat transfer data were correlated in terms of relevant dimensionless parameters. Empirical correlations for the average Nusselt number, in terms of Reynolds number, Rayleigh number and the ratio of Grashof to Reynolds number are given.

  18. Two-Gradient Convection in a Vertical Slot with Maxwell-Cattaneo Heat Conduction

    SciTech Connect

    Papanicolaou, N. C. [Department of Computer Science, University of Nicosia, P.O. Box 24005, 1700 Nicosia (Cyprus); Christov, C. I. [Department of Mathematics, University of Louisiana at Lafayette, LA 70504-1010 (United States); Jordan, P. M. [Entropy Reversal Consultants (L.L.C), P. O. Box 691, Abita Springs, LA 70420 (United States); Code 7181, Naval Research Lab., Stennis Space Ctr., MS 39529 (United States)

    2009-10-29

    We study the effect of the Maxwell-Cattaneo law of heat conduction (MCHC) on the 1D flow in a vertical slot subject to both vertical and horizontal temperature gradients. The gravitational acceleration is allowed to oscillate, which provides an opportunity to investigate the quantitative contribution of thermal inertia as epitomized by MCHC. The addition of the time derivative in MCHC increases the order of the system. We use a spectral expansion with Rayleigh's beam functions as the basis set, which is especially suited to fourth order boundary value problems (BVP). We show that the time derivative (relaxation of the thermal flux) has a dissipative nature and leads to the appearance of purely real negative eigenvalues. Yet it also increases the absolute value of the imaginary part and decreases the absolute value of the real part of the complex eigenvalues. Thus, the system has a somewhat more oscillatory behavior than the one based on Fourier's heat conduction law (FHC)

  19. Explicit solutions of a gravity-induced film flow along a convectively heated vertical wall.

    PubMed

    Raees, Ammarah; Xu, Hang

    2013-01-01

    The gravity-driven film flow has been analyzed along a vertical wall subjected to a convective boundary condition. The Boussinesq approximation is applied to simplify the buoyancy term, and similarity transformations are used on the mathematical model of the problem under consideration, to obtain a set of coupled ordinary differential equations. Then the reduced equations are solved explicitly by using homotopy analysis method (HAM). The resulting solutions are investigated for heat transfer effects on velocity and temperature profiles. PMID:24453862

  20. Turbulent budgets of natural convection in an infinite, differentially heated, vertical channel

    Microsoft Academic Search

    T. A. M. Versteegh; F. T. M. Nieuwstadt

    1998-01-01

    A Direct Numerical Simulation (DNS) of natural convection flow in an infinite, differentially heated, vertical channel has been performed at four Rayleigh numbers varying from 5.4×105 to 5.0×106 for Pr=0.709. The attention will be focused on the turbulent Reynolds-stresses, fluxes, variances and their budgets. We will interpret the budgets in terms of the physical processes that determine this flow. In

  1. Mixed convection heat transfer from a vertical plate to non-Newtonian fluids

    Microsoft Academic Search

    T.-Y. Wang

    1995-01-01

    The nonsimilar boundary-layer analysis of steady laminar mixed-convection heat transfer between a vertical plate and non-Newtonian fluids is extended and unified. A mixed-convection parameter ? is proposed to replace the conventional Richardson number, Gr\\/Re2\\/(2?n) and to serve as a controlling parameter that determines the relative importance of the forced and the free convection. The value of mixed-convection parameter lies between

  2. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    PubMed

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter. PMID:25302782

  3. Unsteady Boundary Layer Flow and Heat Transfer of a Casson Fluid past an Oscillating Vertical Plate with Newtonian Heating

    PubMed Central

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter. PMID:25302782

  4. Applicability of Related Data, Algorithms, and Models to the Simulation of Ground-Coupled Residential Hot Water Piping in California

    SciTech Connect

    Warner, J.L.; Lutz, J.D.

    2006-01-01

    Residential water heating is an important consideration in California?s building energy efficiency standard. Explicit treatment of ground-coupled hot water piping is one of several planned improvements to the standard. The properties of water, piping, insulation, backfill materials, concrete slabs, and soil, their interactions, and their variations with temperature and over time are important considerations in the required supporting analysis. Heat transfer algorithms and models devised for generalized, hot water distribution system, ground-source heat pump and ground heat exchanger, nuclear waste repository, buried oil pipeline, and underground electricity transmission cable applications can be adapted to the simulation of under-slab water piping. A numerical model that permits detailed examination of and broad variations in many inputs while employing a technique to conserve computer run time is recommended.

  5. The global response to vertical diabatic heating structures associated with the Madden-Julian oscillation derived from TRMM estimates

    NASA Astrophysics Data System (ADS)

    Taylor, J.; Woolnough, S.; Inness, P.

    2013-12-01

    The anomalous global atmospheric circulation associated with the Madden-Julian oscillation (MJO) is examined using composite vertical anomalous diabatic heating structures based on Tropical Rainfall Measuring Mission (TRMM) estimates and reanalysis datasets and integrating a primitive equations model. Variations in the dynamical response from the observational and reanalysis products are investigated in relation to the detailed structure of the vertical structure of heating of the MJO, with specific focus of the role of the westward tilting with altitude in the heating, clearly evident in three reanalysis heating structures but is less well pronounced in the TRMM heating structures. It was found that the atmospheric response to the reanalysis heatings were far more consistent compared to the responses from the TRMM heating estimates. Examination of the moisture flux during the main active phase of the MJO revealed a surplus in moisture convergence ahead of the anomalous heating from each of the reanalysis integrations, which was found to be directly attributed to the vertical tilt in heating structure. In contrast, the response to the TRMM heatings showed no phase shift in moisture convergence in relation to the convective heating and was understood to be a consequence of the weaker representation of vertical tilting in heating structure. It was suggested that the westward tilt in heating could therefore play an important role in promoting convection east of the main heating region. The dynamical response to composite vertical diabatic heating structures associated with the MJO from simulations with Unified Model (UM) HadGEM3 with standard and enhanced (x1.5) entrainment rates are also examined to investigate the relationship between the dynamical response to the heating profile and quality of MJO simulations.

  6. A parametrical study on the energetic and exergetic assessment of a solar-assisted vertical ground-source heat pump system used for heating a greenhouse

    Microsoft Academic Search

    Onder Ozgener; Arif Hepbasli

    2007-01-01

    An energetic and exergetic modeling of a solar-assisted vertical ground-source heat pump (GSHP) greenhouse heating system (SAGSHPGHS) for system analysis and performance assessment is presented in this study. Energy (heating coefficient of performance ‘COP’) and exergy efficiencies at various reference and entering water temperatures are also determined. The actual thermal data collected are utilized for the model calculations at different

  7. Vertical variation of apparent and palaeoclimatically corrected heat flow densities in the central baltic shield

    NASA Astrophysics Data System (ADS)

    Kukkonen, Ilmo T.

    1987-10-01

    The vertical variation of heat-flow density in the Central Baltic Shield was studied in 17 drill holes (389-1060 m deep). Apparent heat-flow densities calculated in 100 m depth sections, with typical determination errors smaller than 2 mW/m 2, showed a variation of up to 15 mW/m 2 in single holes. A palaeoclimatic correction for surface temperature variations during the last million years was calculated as a function of depth for each hole with a homogeneous half-space conduction model. If the bedrock temperatures are controlled only by conduction of heat, and the temperature history is accurately known, the palaeoclimatically corrected heat-flow densities should have the same (steady-state) value at all depths throughout a drill hole. In practice, the quality of the correction is indicated by decrease or increase in the standard errors of the drill-hole means of heat-flow density. When the corrections were applied to the measured data, the standard errors decreased in only eight drill holes, and the vertical variation in palaeoclimatically corrected values ranged from a few mW/m 2 to 10 mW/m 2. In some of the holes, this variation can be attributed to heat-flow refraction at inclined conductivity interfaces, resulting in local heat-flow anomalies. However, the most important cause of the variation seems to be groundwater flow in bedrock, i.e., heat transfer disturbing the conductive regime. This notion is supported by heat-flow density-depth plots and temperature-depth plots and the decrease in observed heat-flow variation below 500 m depth, which is the typical depth of rapidly changing fresh groundwater, below which more saline (and stagnant) groudwaters are usually encountered. The present results indicate the following: 1) Groundwater flow can be fairly common in the upper parts of bedrock in the Baltic Shield, and purely conductive circumstances do not necessarily prevail everywhere; 2) palaeoclimatically corrected heat-flow values must be used with great precaution, especially when signs of groundwater flow are present in the data; 3) the palaeoclimatic correction can be applied to study groundwater flow in bedrock indirectly and to test whether a conductive regime prevails or not.

  8. The first-order chemical reaction on a vertical cylinder with constant heat and mass flux

    SciTech Connect

    Ganesan, P.; Rani, H.P.

    1999-07-01

    In recent years, the requirements of modern technology have stimulated interest in fluid flow studies, which involve the interaction of several phenomena. One such study is related to the diffusion of a chemically reactive species in a laminar boundary layer flow over a vertical cylinder with combined heat and mass transfer. This type of problem can arise in the corrosion of offshore pipeline and in the electroplating of cylinder. In slowly rotating cylinders, natural convection dominates the overall rate of heat and mass transfer, which are used as cathodes, in building electrochemical reactors for the continuous production of metal powder. During geophysical exploration, the temperature and mass distribution around the intrusive plays an important role in the geothermal resources. Here the intrusive may be taken as vertical cylinder with heat and mass flux boundary condition. The time required to set in for the intrusive magma is very essential. These type of problems commonly arise in start-up of a chemical reactor and emergency cooling of a nuclear fuel element. In the present study, the diffusion of a chemically reactive species in the convective flow along a vertical cylinder with constant heat and mass flux is considered. The dimensionless, unsteady, coupled and non-linear governing equations of the flow are obtained. A more accurate, unconditionally stable and fast converging implicit finite difference scheme is used to solve the equations. In order to check the accuracy of the numerical scheme, the present results are compared with the results found in the literature. The velocity, temperature and concentration profiles, local and average skin-friction, Nusselt and Sherwood number are studied for both the destructive and generative chemical reactions.

  9. Heat sensitivity of vertical water wall at low mass velocity in supercritical pressure W-shaped flame boiler

    Microsoft Academic Search

    Weishu Wang; Xiaojing Zhu; Qincheng Bi; Gang Wu; Jintao Huang

    The vertical water wall of the once-through boiler is sensitive to heat disturbance because of its smaller water volume compared with the drum boiler. This paper deduced formulas of the sensitivity coefficient of flow and output enthalpy, and made a heat sensitivity analysis for the vertical water wall of a 600 MW supercritical pressure W-shaped flame boiler at a low mass

  10. Natural convection heat transfer of nanofluids along a vertical plate embedded in porous medium.

    PubMed

    Uddin, Ziya; Harmand, Souad

    2013-01-01

    The unsteady natural convection heat transfer of nanofluid along a vertical plate embedded in porous medium is investigated. The Darcy-Forchheimer model is used to formulate the problem. Thermal conductivity and viscosity models based on a wide range of experimental data of nanofluids and incorporating the velocity-slip effect of the nanoparticle with respect to the base fluid, i.e., Brownian diffusion is used. The effective thermal conductivity of nanofluid in porous media is calculated using copper powder as porous media. The nonlinear governing equations are solved using an unconditionally stable implicit finite difference scheme. In this study, six different types of nanofluids have been compared with respect to the heat transfer enhancement, and the effects of particle concentration, particle size, temperature of the plate, and porosity of the medium on the heat transfer enhancement and skin friction coefficient have been studied in detail. It is found that heat transfer rate increases with the increase in particle concentration up to an optimal level, but on the further increase in particle concentration, the heat transfer rate decreases. For a particular value of particle concentration, small-sized particles enhance the heat transfer rates. On the other hand, skin friction coefficients always increase with the increase in particle concentration and decrease in nanoparticle size. PMID:23391481

  11. Natural convection heat transfer of nanofluids along a vertical plate embedded in porous medium

    PubMed Central

    2013-01-01

    The unsteady natural convection heat transfer of nanofluid along a vertical plate embedded in porous medium is investigated. The Darcy-Forchheimer model is used to formulate the problem. Thermal conductivity and viscosity models based on a wide range of experimental data of nanofluids and incorporating the velocity-slip effect of the nanoparticle with respect to the base fluid, i.e., Brownian diffusion is used. The effective thermal conductivity of nanofluid in porous media is calculated using copper powder as porous media. The nonlinear governing equations are solved using an unconditionally stable implicit finite difference scheme. In this study, six different types of nanofluids have been compared with respect to the heat transfer enhancement, and the effects of particle concentration, particle size, temperature of the plate, and porosity of the medium on the heat transfer enhancement and skin friction coefficient have been studied in detail. It is found that heat transfer rate increases with the increase in particle concentration up to an optimal level, but on the further increase in particle concentration, the heat transfer rate decreases. For a particular value of particle concentration, small-sized particles enhance the heat transfer rates. On the other hand, skin friction coefficients always increase with the increase in particle concentration and decrease in nanoparticle size. PMID:23391481

  12. Comparison of DOE-2.1E with Energyplus and TRNSYS for Ground Coupled Residential Buildings in Hot anf Humid Climates Stage 4

    E-print Network

    Andolsun, S.; Culp, C.

    2012-01-01

    sealed boxes in four U.S. climates. 2. INTRODUCTION Ground coupled heat transfer (GCHT) through concrete floor slabs can be a significant component of the total load for heating or cooling in low-rise residential buildings. For a contemporary code... sensible heat losses in temperate and cold climates (Figure 5), which became an important factor that explained the 3% higher heating loads in EnergyPlus than in DOE-2 in these climates (Figure 2). The different air changes obtained from DOE-2...

  13. Investigation of fluid flow and heat transfer in a vertical channel heated from one side by PV elements, part I - Numerical Study

    Microsoft Academic Search

    B. Moshfegh; M. Sandberg

    1996-01-01

    The impetus of this paper is to analyse numerically the fluid flow and heat transfer characteristics of buoyancy-driven convection between two vertical parallel walls, heated from one side. Both convection and radiation heat exchanges are considered as the heat transfer mechanisms by which the thermal energy is transferred into the air. A steady-state two-dimensional model is used for the analysis.

  14. Modeling Vertical Structure and Heat Transport within the Oceans of Ice-covered Worlds (Invited)

    NASA Astrophysics Data System (ADS)

    Goodman, J. C.

    2010-12-01

    Indirect observational evidence provides a strong case for liquid oceans beneath the icy crust of Europa and several other frozen moons in the outer solar system. However, little is known about the fluid circulation within these exotic oceans. As a first step toward understanding circulations driven by buoyancy (rather than mechanical forcing from tides), one must understand the typical vertical structure of temperature, salinity, and thus density within the ocean. Following a common approach from terrestrial oceanography, I have built a "single column convection model" for icy world oceans, which describes the density structure of the ocean as a function of depth only: horizontal variations are ignored. On Earth, this approach is of limited utility, because of the strong influence of horizontal wind-driven currents and sea-surface temperature gradients set in concert with the overlying atmosphere. Neither of these confounding issues is present in an icy world's ocean. In the model, mixing of fluid properties via overturning convection is modeled as a strong diffusive process which only acts when the ocean is vertically unstable. "Double diffusive" processes (salt fingering and diffusive layering) are included: these are mixing processes resulting from the unequal molecular diffusivities of heat and salt. Other important processes, such as heating on adiabatic compression, and freshwater fluxes from melting overlying ice, are also included. As a simple test case, I considered an ocean of Europa-like depth (~100 km) and gravity, heated from the seafloor. To simplify matters, I specified an equation of state appropriate to terrestrial seawater, and a simple isothermal ocean as an initial condition. As expected, convection gradually penetrates upward, warming the ocean to an adiabatic, unstratified equilibrium density profile on a timescale of 50 kyr if 4.5 TW of heat are emitted by the silicate interior; the same result is achieved in proportionally more/less time for weaker/stronger internal heating. Unlike Earth's oceans, I predict that since icy worlds' oceans are heated from below, they will generally be unstratified, with constant potential density from top to bottom. There will be no pycnocline as on Earth, so global ocean currents supported by large-scale density gradients seem unlikely. However, icy world oceans may be "weird" in ways which are unheard-of in terrestrial oceanography The density of sulfate brine has a very different equation of state than chloride brines: does this affect the vertical structure? If the ocean water is very pure, cold water can be less dense than warm. Can this lead to periodic catastrophic overturning, as proposed by other authors? These and other questions are currently being investigated using the single-column convection model as a primary tool.

  15. Potential vertical movement of large heat-generating waste packages in salt.

    SciTech Connect

    Clayton, Daniel James; Martinez, Mario J.; Hardin, Ernest L.

    2013-05-01

    With renewed interest in disposal of heat-generating waste in bedded or domal salt formations, scoping analyses were conducted to estimate rates of waste package vertical movement. Vertical movement is found to result from thermal expansion, from upward creep or heave of the near-field salt, and from downward buoyant forces on the waste package. A two-pronged analysis approach was used, with thermal-mechanical creep modeling, and coupled thermal-viscous flow modeling. The thermal-mechanical approach used well-studied salt constitutive models, while the thermal-viscous approach represented the salt as a highly viscous fluid. The Sierra suite of coupled simulation codes was used for both approaches. The waste package in all simulations was a right-circular cylinder with the density of steel, in horizontal orientation. A time-decaying heat generation function was used to represent commercial spent fuel with typical burnup and 50-year age. Results from the thermal-mechanical base case showed approximately 27 cm initial uplift of the package, followed by gradual relaxation closely following the calculated temperature history. A similar displacement history was obtained with the package density set equal to that of salt. The slight difference in these runs is attributable to buoyant displacement (sinking) and is on the order of 1 mm in 2,000 years. Without heat generation the displacement stabilizes at a fraction of millimeter after a few hundred years. Results from thermal-viscous model were similar, except that the rate of sinking was constant after cooldown, at approximately 0.15 mm per 1,000 yr. In summary, all calculations showed vertical movement on the order of 1 mm or less in 2,000 yr, including calculations using well-established constitutive models for temperature-dependent salt deformation. Based on this finding, displacement of waste packages in a salt repository is not a significant repository performance issue.

  16. Flow Boiling Heat Transfer in a Long, Small Diameter, Vertically Oriented, Uniformly Heated Tube

    Microsoft Academic Search

    Bradley Allan Statham

    2009-01-01

    A thermalhydraulics experiment was constructed at McMaster University that is capable of measuring heat transfer data for test sections up to 1 m long at pressures up to 10.0 MPa. The test section was powered by a 96 kW DC power supply with digital control. Inlet temperature was controlled using a 40 kW RMS AC welding power supply. The experiment

  17. Downflow heat transfer in a heated ribbed vertical annulus with a cosine power profile

    SciTech Connect

    Anderson, J.L.; Condie, K.G.; Larson, T.K.

    1991-10-01

    Experiments designed to investigate downflow heat transfer in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2c series, which was a follow on series to the ECS-2b series, conducted specifically to provide additional data on the effect of different powers at the same test conditions, for use in evaluation of possible power effects on the aluminum temperature measurements. Electrical powers at 90%, 100%, and 110% of the power required to result in the maximum aluminum temperature at fluid saturation temperature were used at each set of test conditions previously used in the ECS-2b series. The ECS-2b series was conducted in the same test rig as the previous ECS-2b series. Data and experimental description for the ECS-2b series is provided in a previous report. 18 refs., 25 figs., 3 tabs.

  18. Supermarket with Ground Coupled Carbon Dioxide Refrigeration Plant 

    E-print Network

    Rehault, N.

    2012-01-01

    Warming Potential = 1 (R404A GWP=3700) ? Ozone Depletion Potential = 0 ? Non-inflammable, nontoxic ? High volumetric heat capacity ? Higher efficiency in comparison to plants running with R134a or R404 (at low condensation temperatures...

  19. Comparison of DOE-2.1E with Energyplus and TRNSYS for Ground Coupled Residential Buildings in Hot anf Humid Climates Stage 1

    E-print Network

    Andolsun, S.; Culp, C.

    2011-01-01

    ESL-TR-11-12-08 COMPARISON OF DOE-2.1E WITH ENERGYPLUS AND TRNSYS FOR GROUND COUPLED RESIDENTIAL BUILDINGS IN HOT AND HUMID CLIMATES STAGE 1 “Literature Survey on Slab-on-grade Heat Transfer Models of DOE-2, EnergyPlus and TRNSYS... .................................................................................................................... 4 2. Introduction ........................................................................................................................................... 4 3. Literature Survey on Slab-on-grade Models of DOE-2, EnergyPlus and TRNSYS...

  20. An algorithm to estimate the heating budget from vertical hydrometeor profiles

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Simpson, Joanne; Mccumber, Michael; Adler, Robert; Lang, Stephen

    1990-01-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometeor profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a nonhydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algoritm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  1. An Algorithm to Estimate the Heating Budget from Vertical Hydrometeor Profiles.

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Simpson, Joanne; Lang, Stephen; McCumber, Michael; Adler, Robert; Penc, Richard

    1990-12-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometer profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a non-hydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algorithm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  2. Effects of Prandtl number on free convection heat transfer from a vertical plate to a non-Newtonian fluid

    Microsoft Academic Search

    Ming-Jer Huang; Jhy-Shean Huang; You-Li Chou; Cha’o-Kuang Chen

    1989-01-01

    A study has been conducted to analyze the heat transfer characteristics of non-Newtonian power law fluids on the free convective flow over a vertical flat plate. The analysis includes the inertia force in the momentum equation with a finite Prandtl number. In general, it has been found that the average heat transfer increases with increasing Prandtl number.

  3. A separated flow model for predicting two-phase pressure drop and evaporative heat transfer for vertical annular flow

    Microsoft Academic Search

    Feng Fu; James F. Klausner

    1997-01-01

    A separated flow model has been developed that is applicable to vertical annular two-phase flow in the purely convective heat transfer regime. Conservation of mass, momentum, and energy are used to solve for the liquid film thickness, pressure drop, and heat transfer coefficient. Closure relationships are specified for the interfacial friction factor, liquid film eddy-viscosity, turbulent Prandtl number, and entrainment

  4. Effect of rolling motion on critical heat flux for subcooled flow boiling in vertical tube

    SciTech Connect

    Hwang, J. S.; Park, I. U.; Park, M. Y.; Park, G. C. [Dept. of Energy Systems Engineering, Seoul National Univ., 599 Gwanak-Ro, Gwanak-Gu, Seoul, 151-744 (Korea, Republic of)

    2012-07-01

    This paper presents defining characteristics of the critical heat flux (CHF) for the boiling of R-134a in vertical tube operation under rolling motion in marine reactor. It is important to predict CHF of marine reactor having the rolling motion in order to increase the safety of the reactor. Marine Reactor Moving Simulator (MARMS) tests are conducted to measure the critical heat flux using R-134a flowing upward in a uniformly heated vertical tube under rolling motion. MARMS was rotated by motor and mechanical power transmission gear. The CHF tests were performed in a 9.5 mm I.D. test section with heated length of 1 m. Mass fluxes range from 285 to 1300 kg m{sup -2}s{sup -1}, inlet subcooling from 3 to 38 deg. C and outlet pressures from 13 to 24 bar. Amplitudes of rolling range from 15 to 40 degrees and periods from 6 to 12 sec. To convert the test conditions of CHF test using R-134a in water, Katto's fluid-to-fluid modeling was used in present investigation. A CHF correlation is presented which accounts for the effects of pressure, mass flux, inlet subcooling and rolling angle over all conditions tested. Unlike existing transient CHF experiments, CHF ratio of certain mass flux and pressure are different in rolling motion. For the mass fluxes below 500 kg m{sup -2}s{sup -1} at 13, 16 (region of relative low mass flux), CHF ratio was decreased but was increased above that mass flux (region of relative high mass flux). Moreover, CHF tend to enhance in entire mass flux at 24 bar. (authors)

  5. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosol

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2015-04-01

    In this study, a two-dimensional cloud-resolving model with spectral-bin microphysics is used to investigate the vertical velocity and precipitation associated with three physical processes (i.e., latent heating (LH), cool-pool and ice microphysics) that could determine the aerosol impact on deep convective precipitation. Evaporative cooling in the lower troposphere is found to enhance rainfall under high cloud condensation nuclei (CCN) concentrations versus low in the developing stages of a tropical precipitation system. In contrast, a midlatitude case produced more rainfall under low CCN concentrations. Deep convective invigoration in this case was also via evaporative cooling. Nevertheless, LH release is stronger (especially after initial precipitation) for the case having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH and precipitation processes. Detailed analyses of the individual terms governing convective draft strengths show that temperature buoyancy can enhance updrafts (downdrafts) in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is the same order and acts in the opposite direction. This suggests that the PGF is as important as the LH term in determining convective updraft strength. Water loading is small but on the same order as the net PGF-temperature buoyancy forcing, suggesting that water loading could also be important for cloud vertical velocities. The balance among these terms determines the intensity of convection.

  6. Numerical simulation of buoyant, turbulent flow. I - Free convection along a heated, vertical, flat plate. II - Free and mixed convection in a heated cavity

    Microsoft Academic Search

    W. M. To; J. A. C. Humphrey

    1986-01-01

    Numerical models are presented to predict free and mixed convection low Reynolds number turbulent flows. A k-epsilon model and an algebraic stress model are used for the case of free convection along a heated vertical flat plate. Both models are found to yield accurate results for the mean flow and heat transfer, and measurements compare well with previous predictions. In

  7. Dynamics of the collision of a vortex ring with a vertical heated wall

    NASA Astrophysics Data System (ADS)

    Gelderblom, G.; Palacios-Morales, C. A.; Zenit, R.; Solorio-Ordaz, F. J.

    2012-11-01

    We study the dynamics of the impact of a vortex ring with a vertical heated plate (at constant temperature). Laminar vortex rings were generated with a piston cylinder arrangement. The vertical wall is heated by a thermal bath which is held at constant temperature producing a laminar and stable thermal boundary layer. Measurements of the 2D velocity field were obtained with a PIV technique. The experimental results for the isothermal case are in agreement with previous investigations reported in the literature. To avoid azimuthal instabilities, we mainly conducted experiments for L /D0 = 1 (where L is the piston displacement and D0 is the cylinder inner diameter) with different wall temperatures and vortex translation velocities. For this case, secondary vortices were not observed. Using ink visualization we observed the evolution of the vortex shape. The initial circular shape evolves into a ``cat head'' shape after reaching the wall. The top and bottom regions of the vortex reduce and increase their vorticity, respectively. The sides are stretched and convected. An analysis of the different mechanisms leading to this shape evolution is presented and discussed.

  8. Vertical profiles of aerosol extinction and radiative heating at Niamey, Niger

    NASA Astrophysics Data System (ADS)

    McFarlane, S.; Kassianov, E.; Flynn, C.; Barnard, J.

    2007-12-01

    Land use and land cover changes may lead to increases in Saharan dust outbreaks and increased dust aerosol loading in the atmosphere. It is important to understand the impact of Saharan dust on the Earth's radiation budget in order to improve model simulations of regional and global climate. Details of the radiative impact depend on the amount, vertical profile, and optical properties of the observed aerosol. The ARM Mobile Facility (AMF) was deployed in Niamey, Niger during 2006 as part of the RADAGAST project (Radiative Atmospheric Divergence using ARM Mobile Facility, GERB data and AMMA Stations) in cooperation with the African Monsoon Multidisciplinary Analysis (AMMA) experiment. This deployment represents the first long- term series of measurements of aerosol properties from the surface in the Sahel region and provides an unprecedented opportunity to examine the radiative heating profiles associated with aerosol in this region. Using aerosol optical properties derived from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) and the Atmospheric Emitted Radiance Interferometer (AERI), profiles of relative aerosol extinction from the micropulse lidar (MPL), and measurements of broadband surface radiation at the AMF site, we examine the vertical profile of aerosol extinction and aerosol radiative heating during the dry season (January - March and Oct-Dec, 2006) at Niamey.

  9. The study and development of the empirical correlations equation of natural convection heat transfer on vertical rectangular sub-channels

    NASA Astrophysics Data System (ADS)

    Kamajaya, Ketut; Umar, Efrizon; Sudjatmi, K. S.

    2012-06-01

    This study focused on natural convection heat transfer using a vertical rectangular sub-channel and water as the coolant fluid. To conduct this study has been made pipe heaters are equipped with thermocouples. Each heater is equipped with five thermocouples along the heating pipes. The diameter of each heater is 2.54 cm and 45 cm in length. The distance between the central heating and the pitch is 29.5 cm. Test equipment is equipped with a primary cooling system, a secondary cooling system and a heat exchanger. The purpose of this study is to obtain new empirical correlations equations of the vertical rectangular sub-channel, especially for the natural convection heat transfer within a bundle of vertical cylinders rectangular arrangement sub-channels. The empirical correlation equation can support the thermo-hydraulic analysis of research nuclear reactors that utilize cylindrical fuel rods, and also can be used in designing of baffle-free vertical shell and tube heat exchangers. The results of this study that the empirical correlation equations of natural convection heat transfer coefficients with rectangular arrangement is Nu = 6.3357 (Ra.Dh/x)0.0740.

  10. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube

    SciTech Connect

    Bae, Y. Y.; Hong, S. D.; Kim, Y. W. [Korea Atomic Energy Research Inst., 1045 Daedeokdaero, Daejeon (Korea, Republic of)

    2012-07-01

    A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudo-critical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic over-predictions, as soon as the bulk temperature exceeded the pseudo-critical temperature. The over-predictions might have been resulted from an inapplicability of widely-used turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)

  11. Economic potential of vertical ground-source heat pumps compared to air-source air conditioners in South Africa

    Microsoft Academic Search

    P. J. Petit; J. P. Meyer

    1998-01-01

    This study was undertaken to compare the economic viability in Johannesburg, R.S.A., of vertical ground-source and air-source systems. Capital costs and optimum borehole length of the ground system were determined. Monthly heating and cooling capacities, and COPs were evaluated to determine running costs. Payback periods, net present values and internal rates of return were computed. The vertical ground-source system was

  12. Sensitivity of shortwave radiative flux density, forcing, and heating rates to the aerosol vertical profile

    SciTech Connect

    Guan, Hong; Schmid, Beat; Bucholtz, Anthony; Bergstrom, Robert

    2010-03-31

    The effect of the aerosol vertical distribution on the solar radiation profiles, for idealized and measured profiles of optical properties (extinction and single-scattering albedo (SSA)) during the May 2003 Atmospheric Radiation Measurement (ARM) Aerosol Intensive Observation Period (AIOP), has been investigated using the Rapid Radiative Transfer Model Shortwave (RRTM_SW) code. Calculated profiles of down-welling and up-welling solar fluxes during the AIOP have been compared with the data measured by up- and down-looking solar broadband radiometers aboard a profiling research aircraft. The measured profiles of aerosol extinction, SSA, and water vapor obtained from the same aircraft that carried the radiometers served as the inputs for the model calculations. It is noteworthy that for this study, the uplooking radiometers were mounted on a stabilized platform that kept the radiometers parallel with respect to the earth’s horizontal plane. The results indicate that the shape of the aerosol extinction profiles has very little impact on direct radiative forcings at the top of atmosphere and surface in a cloud-free sky. However, as long as the aerosol is not purely scattering, the shape of the extinction profiles is important for forcing profiles. Identical extinction profiles with different absorption profiles drastically influence the forcing and heating rate profiles. Using aircraft data from 19 AIOP profiles over the Southern Great Plains (SGP), we are able to achieve broadband down-welling solar flux closure within 0.8% (bias difference) or 1.8% (rms difference), well within the expected measurement uncertainty of 1 to 3%. The poorer agreement in up-welling flux (bias -3.7%, rms 10%) is attributed to the use of inaccurate surface albedo data. The sensitivity tests reveal the important role accurate, vertically resolved aerosol extinction data plays in tightening flux closure. This study also suggests that in the presence of a strongly absorbing substance, aircraft flux measurements from a stabilized platform have the potential to determine heating rate profiles. These measurement-based heating rate profiles provide useful data for heating rate closure studies and indirect estimates of single scattering albedo assumed in radiative transfer calculations.

  13. Comparison of DOE-2.1E with Energyplus and TRNSYS for Ground Coupled Residential Buildings in Hot anf Humid Climates Stage 1 

    E-print Network

    Andolsun, S.; Culp, C.

    2011-01-01

    of the Report This report consists of two sections. The first section is the introduction to the significance of the topic. The second section is a literature survey on the primary assumptions and calculation methods of the slab- on-grade heat transfer models...-on-grade models have been developed. Some used simplified methods for slab-on-grade load calculations [3-5]; whereas others developed more detailed models [6]. Comparative studies on ground coupled heat transfer models of current simulation tools showed a high...

  14. Numerical Simulation of the Vertical Upward Flow of Water in a Heated Tube at Supercritical Pressure

    SciTech Connect

    Seong Hoon, Kim; Young In, Kim; Yoon Yeong, Bae; Bong Hyun, Cho [Korea Atomic Energy Research Institute, 150 Deokjin-dong Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2004-07-01

    The vertical upward flow of water in a heated tube at supercritical pressure is numerically simulated by a commercially available computational fluid dynamics code. The IAPWS-95 formulation is used to obtain the water properties, which vary substantially at supercritical condition. To match the simulation with the experiment performed by Yamagata et al. (Int. J. Heat Mass Transfer, Vol. 15, 1972), the mass velocity is set to be 1260 kg/m{sup 2}xs and the wall heat fluxes 233, 465, 698, and 930 kW/m{sup 2}. To examine the reliability of the turbulence model at the supercritical flow, a series of simulations are performed with turbulence models: several Low- Reynolds number k-{epsilon} models, k-{omega} model, SST k-{omega}model, standard k-{epsilon} model, RNG k-{epsilon} model, and realizable k-{epsilon} model. For the last three turbulence models, the standard wall function and the enhanced wall treatment are used as wall boundary conditions. It is found that the predicted wall temperature is sensitive to the height of the grid next to the wall when the bulk enthalpy is around the pseudo-critical point. When the standard wall function is used, results from the RNG k-{epsilon} model and the standard k-{epsilon} model are identical, and the wall temperature predictions are lower than the experiment. Conversely, the predicted wall temperature is higher in the simulations with Low- Reynolds number k-{epsilon} models. The temperature difference between the predictions and the experiment becomes larger as the wall heat flux increases. Low-Reynolds number k-{epsilon} models result in extremely higher wall temperature than the experiment at the highest wall heat flux. Low turbulence kinetic energy resulting from the Low-Reynolds k-{epsilon} models reduces the heat transfer and causes higher wall temperature than the experiment. The mean flow fields and turbulence properties from each turbulence model are examined. It seems that the acceleration, which is caused by the density reduction as the bulk temperature increases, and the buoyancy lead to the inadequate prediction. Modification of the turbulence transport equation may be required to overcome these effects on the prediction of the wall temperature. (authors)

  15. The impact of latent heat release on synoptic-scale vertical motions and the development of an extratropical cyclone system

    NASA Technical Reports Server (NTRS)

    Smith, P. J.; Dare, P. M.; Lin, S.-J.

    1984-01-01

    This study investigates the influence of stable and convective latent heat release on synoptic-scale vertical motions and the corresponding evolution of an extratropical cyclone during a 48 h period of strong development. The cyclone's early evolution was dominated by dry dynamical processes. By midway through the period, however, forcing by latent heat release accounted for over 50 percent of the upward vertical motions, with the convective component dominating. The cyclone's development was most intense during the second 24 h, despite a decrease in latent heat release. During the latter period, the reduced direct latent heat influence may have been augmented by an indirect influence, in which pre-existing dry dynamical forcing was enhanced by diabatic intensification of vorticity and thermal gradients.

  16. Experimental study on convective heat transfer coefficient around a vertical hexagonal rod bundle

    NASA Astrophysics Data System (ADS)

    Makhmalbaf, M. H. M.

    2012-06-01

    Research on convective heat transfer coefficient around a rod bundle has many diverse applications in industry. So far, many studies have been conducted in correlations related to internal and turbulent fully-developed flow. Comparison shows that Dittus-Boelter, Sieder-Tate and Petukhov have so far been the most practical correlations in fully-developed turbulent fluid flow heat transfer. The present study conducts an experimental examination of the validity of these frequently-applied correlations and introduces a manufactured test facility as well. Due to its generalizibility, the unique geometry of this test facility (hexagonal arranged, 7 vertical rods in a hexagonal tube) can fulfil extensive applications. The paper also studies the major deviation sources in data measurements, calibrations and turbulence of fluid flow in this. Finally, regarding to sufficient number of experiments in a vast fluid mean velocity range (3,800 < Re < 40,000), a new curve and correlation are presented and the results are compared with the above mentioned commonly-applied correlations.

  17. Effect of Pressure Stress Work and Viscous Dissipation in Natural Convection Flow along a Vertical Flat Plate with Heat Conduction

    Microsoft Academic Search

    M. A. Alim

    2008-01-01

    In this paper, the effect of viscous dissipation and pressure stress work on free convection flow along a vertical flat plate has been investigated. Heat conduction due to wall thickness b is considered in this investigation. With a goal to attain similarity solutions of the problem posed, the developed equations are made dimensionless by using suitable transformations. The non-dimensional equations

  18. Numerical simulation of mixed convection heat and mass transfer with liquid film cooling along an insulated vertical channel

    Microsoft Academic Search

    M. Feddaoui; A. Mir; E. Belahmidi

    2003-01-01

    A computer code was developed for modelling laminar mixed convection heat and mass transfer with the evaporative cooling of liquid film falling along an insulated vertical channel. The numerical method applied solves the coupled governing equations together with the boundary and interfacial conditions. Results are specifically presented for air–water system. Parametric computations were performed to investigate the effects of Reynolds

  19. Correlation for the fin Nusselt number of natural convective heat sinks with vertically oriented plate-fins

    NASA Astrophysics Data System (ADS)

    Kim, Tae Hoon; Kim, Dong-Kwon; Do, Kyu Hyung

    2013-03-01

    In this paper, a correlation for estimating the fin Nusselt number of natural convective heat sinks with vertically oriented plate-fins is suggested. For this purpose, extensive experimental investigations are performed for various channel widths, heights and input powers. A numerical simulation is conducted by using a commercial tool to verify the present experimental results and examine fluid flow and heat transfer characteristics of a natural convective heat sink. By comparison of the present study and the previous studies, it is shown that the present correlation is widely applicable for Elenbaas numbers between 0.5 and 2 × 106 and is more accurate than previous correlations. Based on an asymptotic approach, it is found that the optimal channel width is independent of the heat sink height but dependent of the heat sink length, the difference between the heat sink base and the ambient temperatures, and fluid property.

  20. Modeling of Heat Transfer in Geothermal Heat Exchangers

    E-print Network

    Cui, P.; Man, Y.; Fang, Z.

    2006-01-01

    Ground-coupled heat pump (GCHP) systems have been gaining increasing popularity for space conditioning in residential and commercial buildings. The geothermal heat exchanger (GHE) is devised for extraction or injection of thermal energy from...

  1. Modeling of Heat Transfer in Geothermal Heat Exchangers 

    E-print Network

    Cui, P.; Man, Y.; Fang, Z.

    2006-01-01

    Ground-coupled heat pump (GCHP) systems have been gaining increasing popularity for space conditioning in residential and commercial buildings. The geothermal heat exchanger (GHE) is devised for extraction or injection of thermal energy from...

  2. The vertical profile of atmospheric heating rate of black carbon aerosols at Kanpur in northern India

    NASA Astrophysics Data System (ADS)

    Tripathi, S. N.; Srivastava, Atul K.; Dey, Sagnik; Satheesh, S. K.; Krishnamoorthy, K.

    Altitude profiles of the mass concentrations of aerosol black carbon (BC) and composite aerosols were obtained from the collocated measurements of these quantities onboard an aircraft, over the urban area of Kanpur, in the Ganga basin of northern India during summer, for the first time in India. The enhancement in the mean BC concentration was observed at ˜1200 m in the summer, but the vertical gradient of BC concentration is less than the standard deviation at that altitude. The difference in the BC altitude profile and columnar concentration in the winter and summer is attributed to the enhanced turbulent mixing within the boundary layer in summer. This effect is more conspicuous with BC than the composite aerosols, resulting in an increase in the BC mass fraction ( FBC) at higher levels in summer. This high BC fraction results in an increase in the lower atmospheric heating rate in both the forenoon, FN and afternoon, AN, but with contrasting altitude profile. The FN profile shows fluctuating trend with highest value (2.1 K day -1) at 300 m and a secondary peak at 1200 m altitudes, whereas the AN profile shows increasing trend with highest value (1.82 K day -1) at 1200 m altitude.

  3. Unsteady Convection Flow and Heat Transfer over a Vertical Stretching Surface

    PubMed Central

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient. PMID:25264737

  4. Unsteady convection flow and heat transfer over a vertical stretching surface.

    PubMed

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient. PMID:25264737

  5. Investigation on the mechanism of abnormal heat transfer of supercritical pressure water in vertically-upward tubes in the large specific heat region

    NASA Astrophysics Data System (ADS)

    Wang, J. G.; Li, H. X.; Guo, B.; Yu, S. Q.; Zhang, Y. Q.; Chen, T. K.

    2010-03-01

    The heat transfer characteristics of water at supercritical pressures in a vertically-upward internally-ribbed tube are investigated experimentally to investigate the mechanism of abnormal heat transfer of supercritical pressure water in the so-called large specific heat region. One kind optimized internally-ribbed tube is used in this study. The tube is made of SA-213T12 steel with an outer diameter of 31.8 mm and a wall thickness of 6 mm and the mean inside diameter of the tube is measured to be 17.63 mm. According to experimental data, the characteristics and mechanisms of the heat transfer enhancement and also the heat transfer deterioration of supercritical pressure water in the large specific heat region are discussed respectively. The heat transfer enhancement of the supercritical pressure water in the large specific heat region is believed to be a result of combined effect caused by the rapid variations of thermophysical properties of the supercritical pressure water in the large specific heat region, and the same is true of the heat transfer deterioration. The drastic changes in thermophysical properties near the pseudocritical points, especially the sudden rise in the specific heat of water at supercritical pressures, may result in the occurrence of the heat transfer enhancement, while the covering of the heat transfer surface by fluids lighter and hotter than the bulk fluid makes the heat transfer deteriorated eventually and explains how this lighter fluid layer forms. It is also found that the heat transfer deterioration of water at supercritical pressures is similar to the DNB (departure from nucleate boiling) at subcritical pressures in mechanism.

  6. Experimental investigation of convection heat transfer of CO{sub 2} at supercritical pressures in a vertical circular tube

    SciTech Connect

    Li, Zhi-Hui; Jiang, Pei-Xue; Zhao, Chen-Ru; Zhang, Yu. [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

    2010-11-15

    The convection heat transfer characteristics of supercritical CO{sub 2} in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermo-physical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not for downward flows. Comparison of the experimental data for inlet Reynolds numbers from 3800 to 20,000 with some well-known empirical correlations showed large differences especially when the heat transfer deteriorates and then recovers when the effect of buoyancy is significant. The experimental data was used to develop modified local turbulent Nusselt number correlations for supercritical CO{sub 2} flowing in vertical small circular tubes. (author)

  7. Energy analysis of a solar-ground source heat pump system with vertical closed-loop for heating applications

    Microsoft Academic Search

    Kadir Bakirci; Omer Ozyurt; Kemal Comakli; Omer Comakli

    2011-01-01

    A heat pump system is the ideal way to extend the heat supply of existing oil or gas fired heating system. Consumption costs are lowered through the use of free energy from the environment, and the dependence on fossils fuels simultaneously reduces. In order to investigate the performance of the solar-ground source heat pump system in the province of Erzurum

  8. Circulation, heat exchange and vertical structure of the Hornsund - the Svalbard Archipelago fiord.

    NASA Astrophysics Data System (ADS)

    Jakacki, Jaromir; Przyborska, Anna; Kosecki, Szymon; Sundfjord, Arild

    2015-04-01

    The Hornsund fjord is located in the southwestern part of Spitsbergen- the biggest island of the Svalbard Archipelago. The fjord is influenced by two major currents in this area. The first one is the current carrying the cold and less saline waters around the southern Spitsbergen tip, often called the Sørkapp Current or the South Cape Current. The second is the well-known West Spitsbergen Current (WSC), carrying salty and warm Atlantic Waters through Fram Strait into the Arctic Ocean. From a biological point of view, Hornsund can be treated as a young unstable system or cold system, which suggests that it is under an influence of the South Cape Current. Because of limited measurements in this area, the hydrodynamic model MIKE3D has been implemented for this fjord to diagnose which current has the main influence on Hornsund. The fjord domain was extended into the shelf area. At the lateral boundary of the extended domain, data from the ROMS simulation of the Svalbard area made by the Norwegian Institute of Marine Research (IMR) with resolution of 800 m have been used. Atmospheric data from European Centre for Medium Weather Forecast (ECMWF) were employed as well as from the Global Data Assimilation System (GDAS, 1 and 0.5 degrees) reanalysis that uses metrological data from Polish Polar Station located in Hornsund. Based on 5 years of simulation (2005-2010) seasonal and annual general circulation in the fjord has been described. Estimation of the heat transport between fjord and ocean, and between fjord and atmosphere will permit to establish the heat budget and help to evaluate the influence of the South Cape Current and WSC on the fjord ecosystem development. An influence of the fresh water fluxes and vertical structure of water masses and their transformations will be also discussed. This work was partially performed in the frame of the projects GAME (DEC-2012/04/A/NZ8/00661) and AWAKE2 (Pol-Nor/198675/17/2013)

  9. Numerical modeling of a 2K J-T heat exchanger used in Fermilab Vertical Test Stand VTS-1

    SciTech Connect

    Gupta, Prabhat Kumar [Raja Ramanna Centre for Advanced Technology (RRCAT), Indore (MP), India; Rabehl, Roger [FNAL

    2014-07-01

    Fermilab Vertical Test Stand-1 (VTS-1) is in operation since 2007 for testing the superconducting RF cavities at 2 K. This test stand has single layer coiled finned tubes heat exchanger before J-T valve. A finite difference based thermal model has been developed in Engineering Equation Solver (EES) to study its thermal performance during filling and refilling to maintain the constant liquid level of test stand. The model is also useful to predict its performance under other various operating conditions and will be useful to design the similar kind of heat exchanger for future needs. Present paper discusses the different operational modes of this heat exchanger and its thermal characteristics under these operational modes. Results of this model have also been compared with the experimental data gathered from the VTS-1 heat exchanger and they are in good agreement with the present model.

  10. A transient two-dimensional finite volume model for the simulation of vertical U-tube ground heat exchangers

    SciTech Connect

    Yavuzturk, C.; Spitler, J.D.; Rees, S.J.

    1999-07-01

    The ability to predict both the long-term and short-term behavior of ground loop heat exchangers is critical to the design and energy analysis of ground source heat pump systems. A numerical model for the simulation of transient heat transfer in vertical ground loop heat exchangers is presented. The model is based on a two-dimensional fully implicit finite volume formulation. Numerical grids have been generated for different pipe sizes, shank spacing and borehole sizes using an automated parametric grid generation algorithm. The numerical method and grid generation techniques have been validated against an analytical model. The model has been developed with two main purposes in mind. The first application is used in a parameter estimation technique used to find the borehole thermal properties from short time scale test data. The second application is the calculation of nondimensional temperature response factors for short time scales that can be used in annual energy simulation.

  11. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    NASA Technical Reports Server (NTRS)

    Kassemi, Siavash A.

    1988-01-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  12. Effects of mass transfer on flow past an impulsively started infinite vertical plate with constant heat flux and chemical reaction

    Microsoft Academic Search

    U. N. Das; R. Deka; V. M. Soundalgekar

    1994-01-01

    An exact solution to the flow due to impulsive motion of an infinite vertical plate in its own plane in the presence of i)\\u000a species concentration ii) constant heat flux at the plate iii) chemical reaction of first order, has been derived by the Laplace-transform\\u000a technique. Velocity and concentration profiles are shown on graphs. It is observed that due to

  13. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    PubMed

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  14. Experimental investigation of free-convection heat transfer in vertical tube at large Grashof numbers / E. R. G. Eckert, A. J. Diaguila

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Diaguila, A J

    1952-01-01

    Local free-convection heat-transfer coefficients and temperature fields in the turbulent flow range were obtained within a vertical, stationary tube closed at the boom, heated along its walls, and having a length-to-diameter ratio of 5. Convective heat-transfer coefficients were correlated by the general relations for free-convection heat transfer. These coefficients, converted to dimensionless Nusselt numbers were 35 percent below known relations for vertical flat plates. Air temperature measurements within the tube indicated a thin boundary layer along the heated wall surface and unstable conditions in the air flow.

  15. Free convection flow past an impulsively started infinite vertical porous plate with Newtonian heating in the presence of heat generation and viscous dissipation

    NASA Astrophysics Data System (ADS)

    Kamran, M.; Narahari, M.; Jaafar, A.

    2014-10-01

    The effects of heat generation and viscous dissipation on free convective flow past an impulsively started infinite vertical porous plate with Newtonian heating have been investigated. The governing boundary layer equations are solved by using an analytical technique known as Homotopy Analysis Method (HAM). The effects of heat source parameter (Q), suction parameter (s), Eckert number (Ec) and Grashof number (Gr) on the velocity and temperature fields are determined. The study revealed that the fluid temperature increases by increasing heat generation and Eckert number whereas it decreases with increasing suction velocity. The present results are compared with the exact solution results in the absence of viscous dissipation and it is found that the HAM results coincide with the exact solution results.

  16. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Olson, W. S.; Meneghini, R.; Yang, S.; Simpson, J.; Kummerow, C.; Smith, E.

    2000-01-01

    This paper represents the first attempt to use TRMM rainfall information to estimate the four dimensional latent heating structure over the global tropics for February 1998. The mean latent heating profiles over six oceanic regions (TOGA COARE IFA, Central Pacific, S. Pacific Convergence Zone, East Pacific, Indian Ocean and Atlantic Ocean) and three continental regions (S. America, Central Africa and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm estimated heating profiles. Three different latent heating algorithms, the Goddard Convective-Stratiform (CSH) heating, the Goddard Profiling (GPROF) heating, and the Hydrometeor heating (HH) are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are quite similar. They all can identify the areas of major convective activity (i.e., a well defined ITCZ in the Pacific, a distinct SPCZ) in the global tropics. The magnitude of their estimated latent heating release is also not in bad agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm estimated heating profiles only show one maximum heating level, and the level varies between convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. By contrast, two maximum heating levels were found using the GPROF heating and HH algorithms. The latent heating profiles estimated from all three methods can not show cooling between active convective events. We also examined the impact of different TMI (Multi-channel Passive Microwave Sensor) and PR (Precipitation Radar) rainfall information on latent heating structures.

  17. Experimental Study on Condensation Heat Transfer of Ethanol-Water Vapor Mixtures on Vertical Micro-tubes

    NASA Astrophysics Data System (ADS)

    Chen, Xiping; Wang, Jinshi; Qin, Junchao; Chong, Daotong; Huang, Ronghai; Yan, Junjie

    2015-05-01

    The paper presents an experimental investigation of Marangoni condensation heat transfer of ethanol-water vapor mixtures on vertical micro-tubes with an outer diameter of 0.793 mm, 1.032 mm, and 1.221 mm. Experiments were performed over a wide range of ethanol mass fractions in vapor mixtures for different vapor velocities and pressures. Condensation heat transfer coefficients behaved nonlinear characteristics, increased, and then decreased with increasing vapor-to-surface temperature difference. Under the same experimental conditions, the condensation heat transfer coefficient at a 2 % ethanol mass fraction in vapor was the highest. At low ethanol mass fractions, the condensation heat transfer coefficient of the ethanol-water vapor mixture was 2 to 3 times greater than that for pure steam. The effect of vapor pressure and velocity on condensation heat transfer suggested a positive tendency on each micro-tube for all vapor mixtures with different ethanol mass fraction. Results showed that condensation heat transfer coefficients on micro-tubes with a diameter of 1.032 mm were higher than those on the other two micro-tubes, suggesting that there existed a critical diameter which gave the largest condensation heat transfer coefficient.

  18. A Review of Ground Coupled Heat Pump Models Used in Whole-Building Computer Simulation Programs

    E-print Network

    Do, S. L.; Haberl, J. S.

    ) - - Yes (Version 110) Water source HP g-function eQUEST Yes Water source HP g-function EnergyPlus Yes Water source HP g-function TRNSYS Yes Water source HP DST EnergyGauge USA Yes (Residential use only) Geothermal HP - DOE-2 ESL-HH-10... documented models, which could easily model complex building shapes with acceptable run times. Hence, there is a need to develop such a model. REFERENCES ASHRAE 2007. ASHRAE Handbook-HVAC Applications: Geothermal Energy. American Society...

  19. Field Performance of a Ground-Coupled Heat Pump in Abilene, Texas 

    E-print Network

    Dobson, M.; O'Neal, D. L.; Aldred, W.; Margo, R.

    1994-01-01

    temperatures at various depths and radial locations. Water and air flow rates were measured twice during the monitored period, and have remained constant. The measured quantities allow calculation of instantaneous capacity, power, coefficient of performance...

  20. Numerical simulation of mixed convection heat and mass transfer with liquid film cooling along an insulated vertical channel

    NASA Astrophysics Data System (ADS)

    Feddaoui, M.; Mir, A.; Belahmidi, E.

    2002-08-01

    A computer code was developed for modelling laminar mixed convection heat and mass transfer with the evaporative cooling of liquid film falling along an insulated vertical channel. The numerical method applied solves the coupled governing equations together with the boundary and interfacial conditions. Results are specifically presented for air-water system. Parametric computations were performed to investigate the effects of Reynolds number, inlet liquid temperature and inlet liquid mass flow rate on the liquid film cooling mechanism. The results indicate that the latent heat transfer is a main mechanism for heat removal from the interface. Additionally, significant liquid cooling results for the system with a higher gas flow Reynolds number Re, a lower liquid flow rate ?0 or a higher inlet liquid temperature TL0.

  1. Effects of nanoparticle migration on hydromagnetic mixed convection of alumina/water nanofluid in vertical channels with asymmetric heating

    NASA Astrophysics Data System (ADS)

    Malvandi, A.; Ganji, D. D.

    2015-02-01

    The effects of nanoparticle migration on mixed convection of alumina/water nanofluid inside a vertical channel in the presence of a uniform magnetic field have been investigated theoretically. Walls are subjected to different heat fluxes; qlw'' for the left wall and qrw'' for the right wall, and nanoparticles are assumed to have a slip velocity relative to the base fluid induced by the Brownian motion and thermophoresis. Considering hydrodynamically and thermally fully developed flow, the governing equations including continuity, momentum, and energy equations have been reduced to two-point ordinary boundary value differential equations and they have been solved numerically. It is shown that nanoparticles eject themselves from the heated walls, construct a depleted region, and accumulate in the core region, but they are more likely to accumulate toward the wall with the lower heat flux. In addition, inclusion of nanoparticles in the presence of a magnetic field has a negative effect on the performance.

  2. Diurnal and vertical variability of the sensible heat and carbon dioxide budgets in the atmospheric surface layer

    USGS Publications Warehouse

    Casso-Torralba, P.; de Arellano, J. V. -G.; Bosveld, F.; Soler, M.R.; Vermeulen, A.; Werner, C.; Moors, E.

    2008-01-01

    The diurnal and vertical variability of heat and carbon dioxide (CO2) in the atmospheric surface layer are studied by analyzing measurements from a 213 in tower in Cabauw (Netherlands). Observations of thermodynamic variables and CO2 mixing ratio as well as vertical profiles of the turbulent fluxes are used to retrieve the contribution of the budget terms in the scalar conservation equation. On the basis of the daytime evolution of turbulent fluxes, we calculate the budget terms by assuming that turbulent fluxes follow a linear profile with height. This assumption is carefully tested and the deviation ftom linearity is quantified. The budget calculation allows us to assess the importance of advection of heat and CO2 during day hours for three selected days. It is found that, under nonadvective conditions, the diurnal variability of temperature and CO2 is well reproduced from the flux divergence measurements. Consequently, the vertical transport due to the turbulent flux plays a major role in the daytime evolution of both scalars and the advection is a relatively small contribution. During the analyzed days with a strong contribution of advection of either heat or carbon dioxide, the flux divergence is still an important contribution to the budget. For heat, the quantification of the advection contribution is in close agreement with results from a numerical model. For carbon dioxide, we qualitatively corroborate the results with a Lagrangian transport model. Our estimation of advection is compared with, traditional estimations based on the Net Ecosystem-atmosphere Exchange (NEE). Copyright 2008 by the American Geophysical Union.

  3. Heat transfer enhancement of dropwise condensation on a vertical surface with round shaped grooves

    Microsoft Academic Search

    Masaaki Izumi; Satoshi Kumagai; Ryohachi Shimada; Norio Yamakawa

    2004-01-01

    In dropwise condensation, the behavior of falling drops strongly affects the heat transfer. It is expected that the heat transfer during dropwise condensation would be enhanced if falling drops more frequently and widely sweep drops in the lower part. In this paper, we investigated heat transfer characteristics of dropwise condensation on the surface with grooves cut in a round shape.

  4. Numerical study of heat transfer enhancement in mixed convection flow along a vertical plate with heat source/sink utilizing nanofluids

    NASA Astrophysics Data System (ADS)

    Rana, P.; Bhargava, R.

    2011-11-01

    Steady, mixed convection laminar boundary layer flow of incompressible nanofluid along the vertical plate with temperature dependent heat source/sink has been investigated numerically. The resulting non-linear governing equations (obtained with the Boussinesq approximation) are solved, using a robust, extensively validated, variational finite element method (FEM) for both spherical and cylindrical shaped nanoparticles with volume fraction ranging up to 4%, with associated boundary conditions and the effect of the parameters governing the problem are discussed. Different water-based nanofluids containing Cu, Ag, CuO, Al 2O 3, and TiO 2 are taken into consideration. The results show that the average Nusselt number is found to decrease for Ag, Cu, CuO, Al 2O 3, and TiO 2. The present study is of immediate interest in next-generation solar film collectors, heat exchangers technology, materials processing exploiting vertical surfaces, geothermal energy storage and all those processes which are highly affected with heat enhancement concept.

  5. OPTIMIZATION OF HYBRID GEOTHERMAL HEAT PUMP SYSTEMS Scott Hackel, Graduate Research Assistant; Gregory Nellis, Professor; Sanford Klein,

    E-print Network

    Wisconsin at Madison, University of

    1 OPTIMIZATION OF HYBRID GEOTHERMAL HEAT PUMP SYSTEMS Scott Hackel, Graduate Research Assistant, Madison, WI, United States Abstract: Hybrid ground-coupled heat pump systems (HyGCHPs) couple conventional ground- coupled heat pump (GCHP) equipment with supplemental heat rejection or extraction systems

  6. Application of Heat Transfer Enhancement on Vertical Thermosyphon Reboilers Using Tube Inserts

    Microsoft Academic Search

    Mohamad Reza Jafari Nasr; Mehdi Tahmasbi

    2006-01-01

    Vertical thermosyphon reboilers and evaporators are widely used in the process industries. However, increasing the thermal efficiency of these units is very difficult. They are commonly used for about 70% of all evaporation duties in chemical industries. The flow in these units depends on the amount of buoyancy created by vaporization. The flow rate is therefore related not only to

  7. Stability of a vertical liquid film with consideration of the marangoni effect and heat exchange with the environment

    NASA Astrophysics Data System (ADS)

    Burmistrova, O. A.

    2014-05-01

    The stability of a free vertical liquid film under the combined action of gravity and thermocapillary forces has been studied. An exact solution of the Navier-Stokes and thermal conductivity equations is obtained for the case of plane steady flow with constant film thickness. It is shown that if the free surfaces of the film are perfectly heat insulated, the liquid flow rate through the cross section of the layer is zero. It is found that to close the model with consideration of the heat exchange with the environment, it is necessary to specify the liquid flow rate and the derivative of the temperature with respect to the longitudinal coordinate or the flow rate and the film thickness. The stability of the solution with constant film thickness at small wave numbers is studied. A solution of the spectral problem for perturbations in the form of damped oscillations is obtained.

  8. Analysis of convective heat and mass transfer at the vertical walls of a street canyon

    Microsoft Academic Search

    Saba Saneinejad; Peter Moonen; Thijs Defraeye; Jan Carmeliet

    2011-01-01

    The combined effects of urbanization and global climate warming give rise to increased temperatures in urbanized areas, a phenomenon called the urban heat island effect. The higher air temperatures have a negative impact on the energy demand for cooling and on the comfort and health of the people residing in urban areas. One way to mitigate the excess heat in

  9. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products for February 1998

    Microsoft Academic Search

    W.-K. Tao; S. Lang; W. S. Olson; R. Meneghini; S. Yang; J. Simpson; C. Kummerow; E. Smith; J. Halverson

    2001-01-01

    This paper represents the first attempt to use Tropical Rainfall Measuring Mission (TRMM) rainfall information to estimate the four-dimensional latent heating structure over the global Tropics for one month (February 1998). The mean latent heating profiles over six oceanic regions [Tropical Ocean and Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) Intensive Flux Array (IFA), central Pacific, South Pacific Convergence

  10. Experimental study of a closed loop vertical ground source heat pump system

    Microsoft Academic Search

    Arif Hepbasli; Ozay Akdemir; Ebru Hancioglu

    2003-01-01

    Ground source heat pumps (GSHPs), also known as geothermal heat pumps, are a promising new technology that has been used for the last three years in the Turkish market. The main objective of the present study, which was performed for the first time in Turkey at the university level, is to investigate the performance characteristics of a GSHP system with

  11. Geothermal Studies of the Outokumpu Deep Drill Hole, Finland: Vertical variation in heat flow and palaeoclimatic implications

    NASA Astrophysics Data System (ADS)

    Kukkonen, I. T.; Rath, V.; Kivekäs, L.; Šafanda, J.; ?ermak, V.

    2012-04-01

    Detailed geothermal studies of deep drill holes provide insights to heat transfer processes in the crust, and allow separation of different factors involved, such as palaeoclimatic and structural conductive effects as well as advective fluid flow effects. We present high resolution geothermal results of the 2,516 m deep Outokumpu Deep Drill Hole in eastern Finland drilled in 2004-2005 into a Palaeoproterozoic formation with metasedimentary rocks, ophiolite-derived altered ultramafic rocks and pegmatitic granite. The down-hole temperatures have been logged five times after end of drilling and extend to day 948 after drilling. The hole is completely cored (79% core coverage) and thermal conductivity measurements were done at 1 m intervals. The geothermal results on temperature gradient, thermal conductivity and heat flow density yield an exceptionally detailed data set and indicate a significant vertical variation in gradient and heat flow density. Heat flow density increases from about 28-32 mW m-2 in the uppermost 1000 m to 40-45 mW m-2 at depths exceeding 2000 m. The estimated undisturbed surface heat flow value is 42 mWm-2. We present results on forward and inverse transient conductive models which suggest that the vertical variation in heat flow can mostly be attributed to a palaeoclimatic effect due to ground surface temperature (GST) variations during the last 100,000 years. The modelling suggests that the average GST was about -3…-4°C during the Weichselian glaciation. Holocene GST values are within ±2 degree from the present average GST in Outokumpu (5°C). The topographic hydraulic heads and hydraulic conductivity of crystalline rocks are low which suggests that advective heat transfer in the formation is not significant. The slow replacement of fresh flushing water by saline formation fluids is observed in the hole, but it does not generate significant thermal disturbances in the logs. On the other hand, free sluggish thermal convection is present in the large diameter (22 cm) borehole, and temperature variations in the range of few mK to 0.01 K occur over times of minutes to tens of minutes. Theory suggests that convection cells are about as tall as the drill hole diameter, and thus the free convection is expected to generate only local thermal 'noise'not affecting the general geothermal results. Reference: Physics of the Earth and Planetary Interiors 188 (2011) 9-25 (doi:10.1016/j.pepi.2011.06.002)

  12. Geothermal studies of the Outokumpu Deep Drill Hole, Finland: Vertical variation in heat flow and palaeoclimatic implications

    NASA Astrophysics Data System (ADS)

    Kukkonen, Ilmo T.; Rath, Volker; Kivekäs, Liisa; Šafanda, Jan; ?ermak, Vladimir

    2011-09-01

    Detailed geothermal studies of deep drill holes provide insights to heat transfer processes in the crust, and allow separation of different factors involved, such as palaeoclimatic and structural conductive effects as well as advective fluid flow effects. We present high resolution geothermal results of the 2516 m deep Outokumpu Deep Drill Hole in eastern Finland drilled in 2004-2005 into a Palaeoproterozoic formation with metasedimentary rocks, ophiolite-derived altered ultramafic rocks and pegmatitic granite. The down-hole temperatures have been logged five times after end of drilling and extend to day 948 after drilling. The hole is completely cored (79% core coverage) and thermal conductivity measurements were done at 1 m intervals. The geothermal results on temperature gradient, thermal conductivity and heat flow density yield an exceptionally detailed data set and indicate a significant vertical variation in gradient and heat flow density. Heat flow density increases from about 28 - 32 mW m -2 in the uppermost 1000 m to 40-45 mW m -2 at depths exceeding 2000 m. The estimated undisturbed surface heat flow value is 42 mW m -2. We present results on forward and inverse transient conductive models which suggest that the vertical variation in heat flow can mostly be attributed to a palaeoclimatic effect due to ground surface temperature (GST) variations during the last 100,000 years. The modeling suggests that the average GST was about -3 to -4 °C during the Weichselian glaciation. Holocene GST values are within ±2° from the present average GST in Outokumpu (5 °C). The topographic hydraulic heads and hydraulic conductivity of crystalline rocks are low which suggests that advective heat transfer in the formation is not significant. The slow replacement of fresh flushing water by saline formation fluids is observed in the hole, but it does not generate significant thermal disturbances in the logs. On the other hand, free sluggish thermal convection is present in the large diameter (22 cm) borehole, and temperature variations in the range of few mK to 0.01 K occur over times of minutes to tens of minutes. Theory suggests that convection cells are about as tall as the drill hole diameter, and thus the free convection is expected to generate only local thermal 'noise' not affecting the general geothermal results.

  13. Heat Conduction Characteristics of Vertically Aligned Single-Walled Carbon Nanotubes Measured by Raman Spectroscopy

    E-print Network

    Maruyama, Shigeo

    interface material, TIM)VACNT TIM * 2012 00 00 *1 113-8656 7-3-1 *2 113-8656 7-3-1 *3 510275 135 * 113-8656 7-3-1 E-mail: maruyama@photon.t.u-tokyo.ac.jp #12; TIM VACNT TIM TIM 120~200 o C 400~600 o C (24) VACNT TIM TIM TIM VACNT (multi-walled carbon nanotubes, MWNTs) (25)~(35) (vertically

  14. MHD Forced Convective Laminar Boundary Layer Flow from a Convectively Heated Moving Vertical Plate with Radiation and Transpiration Effect

    PubMed Central

    Uddin, Md. Jashim; Khan, Waqar A.; Ismail, A. I. Md.

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to whilst the magnetic field and mass transfer velocity are taken to be proportional to where is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory. PMID:23741295

  15. The flow structure under mixed convection in a uniformly heated vertical pipe

    E-print Network

    Lee, Jeongik

    2005-01-01

    For decay heat removal systems in the conceptual Gas-cooled Fast Reactor (GFR) currently under development, passive emergency cooling using natural circulation of a gas at an elevated pressure is being considered. Since ...

  16. Vertical heat transfer based on direct microstructure measurements in the ice-free Pacific-side Arctic Ocean: the role and impact of the Pacific water intrusion

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Y.; Kikuchi, T.; Inoue, R.

    2014-12-01

    This study quantifies diapycnal mixing and vertical heat transfer in the Pacific side of the Arctic Ocean, where sea-ice cover has disappeared between July and September in the last few decades. We conducted microstructure measurements in the open water region around the Canada Basin from late summer to fall in 2009 and 2010 using RV Mirai. In the study domain, the dissipation rate of turbulent kinetic energy, ?, is typically as low level as O(10-10) W kg-1, resulting in vertical heat diffusivity of O(10-7) m2 s-1, which is close to the molecular diffusivity of heat, suggesting comparatively little predominance of mechanical turbulent mixing. An exception is the case at the Barrow Canyon, where the strong baroclinic throughflow generates substantial vertical mixing, producing ? >O(10-7) W kg-1, because of the shear flow instability. Meanwhile, in the confluence region, where the warm/salty Pacific water and the cold/fresh Arctic basin water encounter, the micro-temperature profiles revealed a localized enhancement in vertical diffusivity of heat, reaching O(10-5) m2 s-1 or greater. In this region, an intrusion of warm Pacific water creates a horizontally interleaved structure, where the double-diffusive mixing facilitates vertical heat transfer between the intruding Pacific water and the surrounding basin waters.

  17. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already been presented and its validity has been tested against satellite-based retrievals. A detailed spectral radiative transfer model (RTM), already used in a number of planetary and regional studies, has been used in the present study to calculate the vertically distributed aerosol direct radiative effects (DREs) and the associated aerosol heating/cooling profiles within the troposphere. Specific emphasis is given to assessment of the crucial issue of the differences between modeling the aerosol DREs using either columnar aerosol optical properties, as usually done, or vertically layered information on those properties, which is the state of the art and ideal practice. To address this problem, the following experiment has been performed: the same RTM has been used twice with the same meteorological conditions but in the first run (set1) columnar values for aerosol optical depth (AOD) have been used while using vertically distributed AOD in the second run (set2). In the second run vertically layered information for AOD is considered for 20 layers extending from the surface to 20 km a.m.s.l.. The vertical profile of AOD has been mainly based on ECHAM model. The aerosol DREs are computed at the Earth's surface, at TOA and at various levels in the atmosphere. Apart from AOD, the model also requires single-scattering albedo (SSA) and asymmetry parameter (ASY) in 18 different wavelengths, which are obtained by linear interpolation from the available wavelengths in HAC. The comparison between the obtained two sets of DRE (set1 and set2) reveal small, but notable differences which vary from one place to another. Within the atmosphere, the difference -averaged over the four seasons - ranges from -0.3 to 1.7 Wm-2 with a mean value of 0.32 Wm-2. Given the fact that the average column-integrated DREAtm values for the entire Mediterranean region based on columnar aerosol optical properties is 11.44 Wm-2, there is an average variance of 3.7 %, which locally could get to 14.9 %. Differences between the columnar and the vertically layered versions of the model also exist for DRE(TOA)

  18. Augmentation of condensation heat transfer with electrohydrodynamics on vertical enhanced tubes 

    E-print Network

    Motte, Edouard

    1994-01-01

    condensation heat transfer performance on the outside surface of enhanced tubes. R-1 13 is the working fluid. Korodense (3.81 cm O.D.) and Turbo CIII (1.905 cm O.D.) enhanced tubes were tested. Smooth tubes (3.81 cm and 1.905 cm O.D.) served as the basis...

  19. Heat and Mass Transfer in a Second Grade Fluid Over a Stretching Vertical Surface in a Porous Medium

    NASA Astrophysics Data System (ADS)

    Baoku, I. G.; Onifade, Y. S.; Adebayo, L. O.; Yusuff, K. M.

    2015-05-01

    The investigation deals with the combined heat and mass transfer in a mixed convection boundary layer flow over a stretching vertical surface in a porous medium filled with a viscoelastic second grade fluid. The partial differential equations governing the model have been transformed by a similarity transformation and the system of coupled-ordinary differential equations is solved by employing the shooting method with the fifth-order Runge-Kutta-Fehlberg iteration technique. Effects of various values of physical parameters embedded in the flow model on the dimensionless velocity, temperature and concentration distributions are discussed and shown with the aid of graphs. Numerical values of physical quantities, such as the local skin-coefficient, local Nusselt number and local Sherwood number are presented in a tabular form. It is observed that the boundary layer fluid velocity increases as the second grade parameter, mixed convection parameter and Prandtl number increase.

  20. Critical Heat Fluxes of Subcooled Water Flow Boiling Against Outlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Toshiyuki Sato; Takeya Tanimoto; Masahiro Shiotsu; Nobuaki Noda

    2002-01-01

    The critical heat fluxes (CHFs) of subcooled water flow boiling are systematically measured for the flow velocities (u=4.0 to 13.3 m\\/s), the outlet sub-cooling (T{sub sub,out}=3 to 129 K) and the outlet pressure (P{sub out}=800 kPa). The SUS304 test tubes of 3, 6, 9 and 12 mm in inner-diameter, d, and 33, 66, 99 and 133 mm in length, L,

  1. Effect of surfactant on evaporative heat transfer coefficients in vertical film forced convection 

    E-print Network

    Shah, Basit Husain

    1972-01-01

    . (Chem1cal), East Pakistan University of Eng1neering and Technology, Dacca; Directed by: Dr. Ronald Darby A study of the 1nfluence of surfactant on boiling heat transfer has been carried out for water boil1ng at 215'F under down flow condit1ons along... OF CONTENTS Chapter I INTRODUCTION I I LITERATURE SURVEY General Review of Nucleate Boiling Theoretical Treatment of Nucleate Boiling Effect of Surface Tension Effect of Foaming Surface Tension Measurements . III EXPERIMENTAL Preparation of Boiling...

  2. MEASURED SPACE CONDITIONING PERFORMANCE OFA VERTICAL-BORE GROUND SOURCE HEAT PUMP (GSHP) OVER TWELVE MONTHS UNDER SIMULATED OCCUPANCY LOADS

    SciTech Connect

    Ally, Moonis Raza [ORNL; Munk, Jeffrey D [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL

    2014-01-01

    This paper presents monthly performance metrics of a 7.56 kW (2.16 ton) GSHP serving the space conditioning loads of a 251m2 (2700ft2) residential home with a phase change material in its envelope, and a single vertical-bore 94.5m (310 ft) ground loop. The same ground loop also serviced a ground source heat pump water heater. Envelope characteristics are discussed briefly in the context of reducing thermal losses. Data on entering water temperatures, energy extracted from the ground, energy delivered/removed, compressor electricity use, COP, GSHP run times (low and high compressor stages), and the impact of fan and pump energy consumption on efficiency are presented for each month. Both practical as well as research and development issues are discussed. The findings suggest that GSHPs represent a practical technology option to reduce source energy reduction and greenhouse emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 target of generating over 25% of heat consumed in the EU from renewable energy.

  3. A Study on a Perfaormance of Water-Spray-Type Ice Thermal Energy Storage Vessel with Vertical Heat Exchange Plates

    NASA Astrophysics Data System (ADS)

    Yoshimura, Kenji; Koyama, Shigeru; Fukuda, Toshihito; Ohba, Hideki

    A system with a water -embedded-type ice storage vessel is widely used because of its simple structure compactness. However, this ice storage vessel has a disadvantage, that is, the melting rate is very small. The use of falling water film seems to be one of promising ways for solving this disadvantage. We have found in our previous study that the use of the falling water film is very effective, especially for high initial water temperatures. In the present study, we examined the melting performance of a falling-water-film-type ice thermal energy storage vessel with practical size, having vertical heat exchange plates. The results obtained are as follows : the quantity of melting ice increases with increase of the water film flow rate, the melting rate decreases with time because ice surface are decreases with time gradually, the heat transfer coefficient of melting increases with increase of the water film flow rate, and the melting rate increases with increase of the water-spray temperature.

  4. Metal–mold heat transfer coefficients during horizontal and vertical Unsteady-State solidification of Al–Cu and Sn–Pb Alloys

    Microsoft Academic Search

    Carlos A. Santos; Cláudio A. Siqueira; Amauri Garcia; José M. V. Quaresma; Jaime A. Spim

    2004-01-01

    In this work, metal–mold heat transfer coefficients (h) are determined during unidirectional solidification of Al–Cu and Sn–Pb alloys. The effects of casting assembly (horizontal and vertical), alloy composition, material and thickness of the mold and melt superheat are investigated. By using measured temperatures in both casting and metal, together with numerical solutions of the solidification problem, metal–mold heat transfer coefficients

  5. A capital cost comparison of commercial ground-source heat pump systems

    SciTech Connect

    Rafferty, K. [Oregon Inst. of Tech., Klamath Falls, OR (United States). Geo-Heat Center

    1995-12-31

    Commercial ground-source heat pump systems have been installed in a variety of configurations. Among the most common are groundwater, vertical ground-coupled, and hybrid ground-coupled (with cooling tower). This paper reports on a comparison of the capital costs associated with the installation of these three designs. Based on the assumption of equal building loop costs, a comparison is made of those costs associated with the ground-source portion of the system. Sensitivity of cost to a variety of factors including well depth, system capacity and soil (or groundwater temperature) is evaluated. Results indicate that shallow (200 ft [60 m]) groundwater systems are the least cost alternative ranging from 500 $/ton (142 $/kW) at 50 tons (176 kW) to less than 200 $/ton (47 $/kW) at 500 tons (1,760 kW) for capacity range evaluated in this report. When deeper (600 ft to 800 ft [180 m to 240 m]) groundwater wells are required, hybrid and ground-coupled systems are less expensive at system sizes less than about 150 tons (528 kW). Above 1570 tons, groundwater systems are the lowest cost approach. When injection wells are omitted, groundwater systems are the lowest cost alternative down to 100 tons (352 kW), even when requiring two 800 ft (240 m) production wells.

  6. Data, exergy, and energy analysis of a vertical-bore, ground-source heat pump to for domestic water heating under simulated occupancy conditions

    SciTech Connect

    Ally, Moonis Raza [ORNL; Munk, Jeffrey D [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL

    2015-01-01

    Evidence is provided to support the view that greater than two-thirds of energy required to produce domestic hot water may be extracted from the ground which serves as renewable energy resource. The case refers to a 345 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days (3993 F-days) and CDD of 723 C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which captures the water consumption lifestyles of the average family in the United States. The 5.275 (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a renewable energy resource.

  7. Heat transfer and flow behaviour of aqueous suspensions of TiO 2 nanoparticles (nanofluids) flowing upward through a vertical pipe

    Microsoft Academic Search

    Yurong He; Yi Jin; Haisheng Chen; Yulong Ding; Daqiang Cang; Huilin Lu

    2007-01-01

    Stable aqueous TiO2 nanofluids with different particle (agglomerate) sizes and concentrations are formulated and measured for their static thermal conductivity and rheological behaviour. The nanofluids are then measured for their heat transfer and flow behaviour upon flowing upward through a vertical pipe in both the laminar and turbulent flow regimes. Addition of nanoparticles into the base liquid enhances the thermal

  8. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-couples airwaves

    USGS Publications Warehouse

    De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David

    2012-01-01

    In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and infrasound observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by infrasound sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. Infrasound and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic infrasound and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow infrasound to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in infrasound monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.

  9. Characterizing fractured rock aquifers using heated Distributed Fiber-Optic Temperature Sensing to determine borehole vertical flow

    NASA Astrophysics Data System (ADS)

    Read, T. O.; Bour, O.; Selker, J. S.; Le Borgne, T.; Bense, V.; Hochreutener, R.; Lavenant, N.

    2013-12-01

    In highly heterogeneous media, fracture network connectivity and hydraulic properties can be estimated using methods such as packer- or cross-borehole pumping-tests. Typically, measurements of hydraulic head or vertical flow in such tests are made either at a single location over time, or at a series of depths by installing a number of packers or raising or lowering a probe. We show how this often encountered monitoring problem, with current solutions sacrificing either one of temporal or spatial information, can be addressed using Distributed Temperature Sensing (DTS). Here, we electrically heat the conductive cladding materials of cables deployed in boreholes to determine the vertical flow profile. We present results from heated fiber optic cables deployed in three boreholes in a fractured rock aquifer at the much studied experimental site near Ploemeur, France, allowing detailed comparisons with alternative methods (e.g. Le Borgne et al., 2007). When submerged in water and electrically heated, the cable very rapidly reaches a steady state temperature (less than 60 seconds). The steady state temperature of the heated cable, measured using the DTS method, is then a function of the velocity of the fluid in the borehole. We find that such cables are sensitive to a wide range of fluid velocities, and thus suitable for measuring both ambient and pumped flow profiles at the Ploemeur site. The cables are then used to monitor the flow profiles during all possible configurations of: ambient flow, cross-borehole- (pumping one borehole, and observing in another), and dipole-tests (pumping one borehole, re-injection in another). Such flow data acquired using DTS may then be used for tomographic flow inversions, for instance using the approach developed by Klepikova et al., (submitted). Using the heated fiber optic method, we are able to observe the flow response during such tests in high spatial detail, and are also able to capture temporal flow dynamics occurring at the start of both the pumping and recovery phase of cross-borehole- and dipole- tests. In addition, the clear advantage of this is that by deploying a single fiber optic cable in multiple boreholes at a site, the flow profiles in all boreholes can be simultaneously measured, allowing many different pumping experiments to be conducted and monitored in a time efficient manner. Klepikova M. V., Le Borgne T., Bour O., and J-R.de Dreuzy, Inverse modelling of flow tomography experiments in fractured media, submitted to Water Resources Research. Le Borgne T., Bour O., Riley M. S., Gouze P., Pezard P.A., Belghoul A., Lods G., Le Provost R., Greswell R. B., Ellis P.A., Isakov E., and B. J. Last, Comparison of alternative methodologies for identifying and characterizing preferential flow paths in heterogeneous aquifers. Journal of Hydrology 2007, 345, 134-148.

  10. The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

    SciTech Connect

    Keyhani, M.; Miller, W.A.

    1999-11-14

    Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller?s capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.

  11. Effect of Smoke and Moisture on Vertical Heating Rate of Southeast Atlantic

    NASA Astrophysics Data System (ADS)

    Adebiyi, A.; Zuidema, P.

    2012-12-01

    Seasonal biomass burning in the southwestern Africa Savannah produces a layer of dark smoke over the southeast Atlantic Ocean(SEA) with the peak typically occurring during August and September(AS). This absorbing layer, distinctively separated from the underlying stratocumulus deck, has been shown to preserve humidity and cloud cover in the boundary layer by enhancing the buoyancy of the free-tropospheric air above the inversion layer thereby inhibiting the entrainment of dry air through the cloud top. Using the observations from St. Helena Island(15.93S/5.67W) as a representation of SEA, we binned the Integrated Global Radiosonde Archive's(IGRA) soundings for AS by the fine-mode aerosol optical depth(AOD) for smoke using the Moderate Resolution Imaging Spectroradiometer(MODIS). It was noted that higher AOD is associated with relatively positive moisture and cooler temperature anomaly below the boundary layer. We also examine the relative impact of smoke and moisture at the same location by preforming a number experiments using the Santa Barbara DISORT Atmospheric Radiative Transfer model constrained by the averaged sounding and observations from MODIS and CALIPSO satellite products for AS. It was found that for every 0.1 increase in AOD, the average heating rate within the smoke layer increases by approximately 0.83K/day, if there is an underlying cloud due to the reflection of the cloud in shortwave and 0.56K/day, if there is no underlying cloud. The result will aid regional and climate model evaluations of black carbon indirect effect for southeast Atlantic.

  12. Solar energy and heat pumps: evaluation of combined systems for heating and cooling of buildings

    Microsoft Academic Search

    J. W. Andrews; M. A. Catan; P. Le Doux

    1982-01-01

    An analysis of a broad range of solar assisted heat pump systems was carried out. Systems were divided into three categories on the basis of whether ground coupling was included in the system and, if so, whether solar energy was stored in the ground or used in some other way. In the category of non-ground-coupled systems, an advanced air-source heat

  13. Effect of a finite external heat transfer coefficient on the Darcy-Bénard instability in a vertical porous cylinder

    NASA Astrophysics Data System (ADS)

    Barletta, A.; Storesletten, L.

    2013-04-01

    The onset of thermal convection in a vertical porous cylinder is studied by considering the heating from below and the cooling from above as caused by external forced convection processes. These processes are parametrised through a finite Biot number, and hence through third-kind, or Robin, temperature conditions imposed on the lower and upper boundaries of the cylinder. Both the horizontal plane boundaries and the cylindrical sidewall are assumed to be impermeable; the sidewall is modelled as a thermally insulated boundary. The linear stability analysis is carried out by studying separable normal modes, and the principle of exchange of stabilities is proved. It is shown that the Biot number does not affect the ordering of the instability modes that, when the radius-to-height aspect ratio increases, are displayed in sequence at the onset of convection. On the other hand, the Biot number plays a central role in determining the transition aspect ratios from one mode to its follower. In the limit of a vanishingly small Biot number, just the first (non-axisymmetric) mode is displayed at the onset of convection, for every value of the aspect ratio.

  14. Survey of advanced-heat-pump developments for space conditioning

    SciTech Connect

    Fairchild, P.D.

    1981-01-01

    A survey of heat pump projects with special emphasis on those supported by DOE, EPRI, and the Gas Research Institute is presented. Some historical notes on heat pump development are discussed. Market and equipment trends, well water and ground-coupled heat pumps, heat-actuated heat pump development, and international interest in heat pumps are also discussed. 30 references.

  15. Non-equilibrium pressure control of the height of a large-scale, ground-coupled, rotating fluid column

    NASA Astrophysics Data System (ADS)

    Ash, R. L.; Zardadkhan, I. R.

    2013-05-01

    When a ground-coupled, rotating fluid column is modeled incorporating non-equilibrium pressure forces in the Navier-Stokes equations, a new exact solution results. The solution has been obtained in a similar manner to the classical equilibrium solution. Unlike the infinite-height, classical solution, the non-equilibrium pressure solution yields a ground-coupled rotating fluid column of finite height. A viscous, non-equilibrium Rankine vortex velocity distribution, developed previously, was used to demonstrate how the viscous and non-equilibrium pressure gradient forces, arising in the vicinity of the velocity gradient discontinuity that is present in the classical Rankine vortex model, effectively isolate the rotating central fluid column from the outer potential vortex region. Thus, the non-equilibrium region acts to confine and shield the central, rigid-body-like, rotating fluid core, justifying this examination of how such a rotating fluid column can interact with the ground. The resulting non-equilibrium ground-coupled, rotating fluid column solution was employed to estimate the central column heights of three well-documented dust devils, and the central column height predictions were consistent with published dust devil height statistics.

  16. Ongoing Commissioning of a high efficiency supermarket with a ground coupled carbon dioxide refrigeration plant 

    E-print Network

    Rehault, N.; Kalz, D.

    2012-01-01

    envelope, the use of daylight and covered refrigeration units contribute jointly to reach the goals. The key component of the concept is a carbon dioxide refrigeration plant with waste heat recovery. To reduce the efficiency losses in supercritical...

  17. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    PubMed

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  18. Nonlinear Radiation Heat Transfer Effects in the Natural Convective Boundary Layer Flow of Nanofluid Past a Vertical Plate: A Numerical Study

    PubMed Central

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge–Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  19. Ground coupling and single-blow thermal storage in a double-envelope house

    SciTech Connect

    Ghaffari, H T; Jones, R F

    1981-01-01

    The possibility of ground thermal storage and coupling in a double-shell house is investigated. Temperature distribution in the ground, utilizing measured ground temperatures, is obtained, and the amount of heat retrieval is assessed. One experimental model and several hypothetical models are introduced; their effects and advantages are compared.

  20. The geothermal characteristics of the ground and the potential of using ground coupled heat pumps in Cyprus

    Microsoft Academic Search

    G. A. Florides; P. D. Pouloupatis; S. Kalogirou; V. Messaritis; I. Panayides; Z. Zomeni; G. Partasides; A. Lizides; E. Sophocleous; K. Koutsoumpas

    2011-01-01

    The ground can be used as an energy source, an energy sink, or for energy storage and for this reason ground characteristics should be available. Therefore the purpose of this paper is to present the recorded ground temperatures at eight representative sites of Cyprus, in relation to depth, time of year, geology and altitude and discuss the efficiency of Ground

  1. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs. S. America ) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model. Review of other latent heating algorithms will be discussed in the workshop.

  2. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. Additional information is included in the original extended abstract.

  3. Vertical Profiles of Latent Heat Release over the Global Tropics Using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in straitform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMXX), Brazil in 1999 (TRMM- LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  4. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM rainfall products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2001. Rainfall, latent heating and radar reflectivity structures between El Nino (DE 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs. west Pacific, Africa vs. S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in strtaiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  5. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  6. Current status of ground source heat pumps and underground thermal energy storage in Europe

    Microsoft Academic Search

    Burkhard Sanner; Constantine Karytsas; Dimitrios Mendrinos; Ladislaus Rybach

    2003-01-01

    Geothermal Heat Pumps, or Ground Coupled Heat Pumps (GCHP), are systems combining a heat pump with a ground heat exchanger (closed loop systems), or fed by ground water from a well (open loop systems). They use the earth as a heat source when operating in heating mode, with a fluid (usually water or a water–antifreeze mixture) as the medium that

  7. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers

    PubMed Central

    Liu, W. J.; Hu, X. L.; Ying, L. Y.; Chen, S. Q.; Zhang, J. Y.; Akiyama, H.; Cai, Z. P.; Zhang, B. P.

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400?nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355?nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355?nm pulsed laser. These were explained by taking into account of the significant heating effect under 355?nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. PMID:25873327

  8. Combined Effect of Buoyancy Force and Navier Slip on MHD Flow of a Nanofluid over a Convectively Heated Vertical Porous Plate

    PubMed Central

    2013-01-01

    We examine the effect of magnetic field on boundary layer flow of an incompressible electrically conducting water-based nanofluids past a convectively heated vertical porous plate with Navier slip boundary condition. A suitable similarity transformation is employed to reduce the governing partial differential equations into nonlinear ordinary differential equations, which are solved numerically by employing fourth-order Runge-Kutta with a shooting technique. Three different water-based nanofluids containing copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are taken into consideration. Graphical results are presented and discussed quantitatively with respect to the influence of pertinent parameters, such as solid volume fraction of nanoparticles (?), magnetic field parameter (Ha), buoyancy effect (Gr), Eckert number (Ec), suction/injection parameter (fw), Biot number (Bi), and slip parameter (?), on the dimensionless velocity, temperature, skin friction coefficient, and heat transfer rate. PMID:24222749

  9. Combined effect of buoyancy force and Navier slip on MHD flow of a nanofluid over a convectively heated vertical porous plate.

    PubMed

    Mutuku-Njane, Winifred Nduku; Makinde, Oluwole Daniel

    2013-01-01

    We examine the effect of magnetic field on boundary layer flow of an incompressible electrically conducting water-based nanofluids past a convectively heated vertical porous plate with Navier slip boundary condition. A suitable similarity transformation is employed to reduce the governing partial differential equations into nonlinear ordinary differential equations, which are solved numerically by employing fourth-order Runge-Kutta with a shooting technique. Three different water-based nanofluids containing copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are taken into consideration. Graphical results are presented and discussed quantitatively with respect to the influence of pertinent parameters, such as solid volume fraction of nanoparticles (?), magnetic field parameter (Ha), buoyancy effect (Gr), Eckert number (Ec), suction/injection parameter (f w ), Biot number (Bi), and slip parameter ( ? ), on the dimensionless velocity, temperature, skin friction coefficient, and heat transfer rate. PMID:24222749

  10. Velocity and temperature distribution of air in the boundary layer of a vertical plate for free-convective heat transfer

    E-print Network

    Jullienne, Jean Maxime Jose

    1962-01-01

    . . To one end of the piston was attached a thin cord that . was, used . to . control the position of the Figgz'g 3 BLOWER COOLING COIL TO COOL CHAMBER AIR HEATING COIL TO HEAT CHAMBER AIR I I ci J BLOWER WINDO ANEM PROB TEMP. INST I 1 I FOR I...

  11. Comparison of air-launched and ground-coupled configurations of SFCW GPR in time, frequency and wavelet domain

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; De Pue, Jan; Cornelis, Wim; Van Meirvenne, Marc

    2015-04-01

    A stepped frequency continuous wave (SFCW) ground penetrating radar (GPR) system produces waveforms consisting of a sequence of sine waves with linearly increasing frequency. By adopting a wide frequency bandwidth, SFCW GPR systems offer an optimal resolution at each achievable measurement depth. Furthermore, these systems anticipate an improved penetration depth and signal-to-noise ratio (SNR) as compared to time-domain impulse GPRs, because energy is focused in one single frequency at a time and the phase and amplitude of the reflected signal is recorded for each discrete frequency step. However, the search for the optimal practical implementation of SFCW GPR technology to fulfil these theoretical advantages is still ongoing. In this study we compare the performance of a SFCW GPR system for air-launched and ground-coupled antenna configurations. The first is represented by a 3d-Radar Geoscope GS3F system operated with a V1213 antenna array. This array contains 7 transmitting and 7 receiving antennae resulting in 13 measurement channels at a spacing of 0.075 m and providing a total scan width of 0.975 m. The ground-coupled configuration is represented by 3d-Radar's latest-generation SFCW system, GeoScope Mk IV, operated with a DXG1212 antenna array. With 6 transmitting and 5 receiving antennae this array provides 12 measurement channels and an effective scan width of 0.9 m. Both systems were tested on several sites representative of various application environments, including a test site with different road specimens (Belgian Road Research Centre) and two test areas in different agricultural fields in Flanders, Belgium. For each test, data acquisition was performed using the full available frequency bandwidth of the systems (50 to 3000 MHz). Other acquisition parameters such as the frequency step and dwell time were varied in different tests. Analyzing the data of the different tests in time, frequency and wavelet domain allows to evaluate different performance aspects of the air-launched and ground-coupled configurations such as acquisition speed, measurement resolution, SNR and penetration depth. Based on this analysis, we highlight the advantages and disadvantages of the different SFCW GPR configurations in different application environments. The authors thank Colette Grégoire and Carl Van Geem of the Belgian Road Research Centre for the collaboration on the road test site. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  12. Experimental and analytical evaluation of a ground-coupled refrigerator-freezer

    SciTech Connect

    Vineyard, E.A. [Vineyard Associates, Knoxville, TN (United States); Horvay, J.B. [Horvay Associates, Isle of Palms, SC (United States); Schulak, E.R. [Edward Schulak Equities, Inc., Birmingham, MI (United States)

    1998-12-31

    In response to efforts to reduce refrigerator-freezer energy consumption, several design options based on using a ground-source heat exchanger as a means of rejecting heat from the cabinet and condenser were investigated for improving the energy efficiency of a 15.5 ft{sup 3} (440 L) domestic refrigerator-freezer. The options included (1) a cooling circuit throughout the cabinet to reduce the cabinet heat gain, (2) a liquid-cooled condenser and smaller compressor, and (3) a secondary cooling circuit in the fresh food section during winter operation. An additional option, increasing the cabinet volume by reducing the insulation thickness, was also investigated as a means of reducing costs. This was accomplished by using the cooling circuit to maintain the same cabinet heat gain as for the original baseline cabinet rather than reduce energy consumption. The modeled results for all the options show that the energy consumption could be reduced by 24.0% with a cabinet cooling circuit, 40.4% with the addition of a liquid-cooled condenser and smaller compressor, and 51.1% from utilizing a fresh food cooling circuit during winter operation. Modeling simulations also show that the cabinet volume could be increased by 2.4 ft{sup 3} (70 L), a 15.3% increase, by utilizing the cabinet cooling circuit to reduce the insulation thickness rather than reduce energy consumption. These improvements do not account for the pumping power required for circulating the coolant. In addition to the modeling exercise, a laboratory prototype was fabricated and tested to experimentally verify the energy consumption of a unit with a cabinet cooling circuit. The resulting energy consumption was 1.35 kWh/d, a substantial energy-efficiency improvement of 24.0% compared to the 1997 model baseline unit (1.78 kWh/d). Abbreviated test results with the addition of a liquid-cooled condenser and smaller compressor show a savings of 39.9% (1.07 kWh/d).

  13. Convective heat transfer to CO{sub 2} at a supercritical pressure flowing vertically upward in tubes and an annular channel

    SciTech Connect

    Bae, Yoon-Yeong; Kim, Hwan-Yeol [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea)

    2009-01-15

    The Super-Critical Water-Cooled Reactor (SCWR) has been chosen by the Generation IV International Forum as one of the candidates for the next generation nuclear reactors. Heat transfer to water from a fuel assembly may deteriorate at certain supercritical pressure flow conditions and its estimation at degraded conditions as well as in normal conditions is very important to the design of a safe and reliable reactor core. Extensive experiments on a heat transfer to a vertically upward flowing CO{sub 2} at a supercritical pressure in tubes and an annular channel have been performed. The geometries of the test sections include tubes of an internal diameter (ID) of 4.4 and 9.0 mm and an annular channel (8 x 10 mm). The heat transfer coefficient (HTC) and Nusselt numbers were derived from the inner wall temperature converted by using the outer wall temperature measured by adhesive K-type thermocouples and a direct (tube) or indirect (annular channel) electric heating power. From the test results, a correlation, which covers both a deteriorated and a normal heat transfer regime, was developed. The developed correlation takes different forms in each interval divided by the value of parameter Bu. The parameter Bu (referred to as Bu hereafter), a function of the Grashof number, the Reynolds number and the Prandtl number, was introduced since it is known to be a controlling factor for the occurrence of a heat transfer deterioration due to a buoyancy effect. The developed correlation predicted the HTCs for water and HCFC-22 fairly well. (author)

  14. Pool boiling heat transfer of deionized and degassed water in vertical\\/horizontal V-shaped geometries

    Microsoft Academic Search

    M.-Y. Wen; C.-Y. Ho

    2003-01-01

    .   \\u000a Nucleate pool boiling using a surface within an angular geometry was conducted in saturated, deionized and degassed water.\\u000a Data were taken at atmospherical pressure and at heat fluxes from 300 W\\/m\\u000a 2 to 51000 W\\/m\\u000a 2 while decreasing the heat flux. The effects of the angle on the initiation of boiling of nearly contact line are documented,\\u000a and

  15. Critical heat-flux experiments under low-flow conditions in a vertical annulus. [PWR; BWR; LMFBR

    SciTech Connect

    Mishima, K.; Ishii, M.

    1982-03-01

    An experimental study was performed on critical heat flux (CHF) at low flow conditions for low pressure steam-water upward flow in an annulus. The test section was transparent, therefore, visual observations of dryout as well as various instrumentations were made. The data indicated that a premature CHF occurred due to flow regime transition from churn-turbulent to annular flow. It is shown that the critical heat flux observed in the experiment is essentially similar to a flooding-limited burnout and the critical heat flux can be well reproduced by a nondimensional correlation derived from the previously obtained criterion for flow regime transition. The observed CHF values are much smaller than the standard high quality CHF criteria at low flow, corresponding to the annular flow film dryout. This result is very significant, because the coolability of a heater surface at low flow rates can be drastically reduced by the occurrence of this mode of CHF.

  16. Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

    SciTech Connect

    Ally, Moonis Raza [ORNL; Munk, Jeffrey D [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL

    2015-01-01

    This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4oC and 21.7oC, respectively. The WA-GSHP shared the same 94.5 m vertical bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.

  17. Boundary Layer Flow and Heat Transfer near Vertical Heated Boreholes in Water-Saturated Rock: An Approach to the THMCB Experiment at DUSEL Homestake

    Microsoft Academic Search

    N. Rumiantsev; R. P. Lowell; L. N. Germanovich; E. L. Sonnenthal; N. Uzunlar; D. Elsworth; B. J. Mailloux; K. Maher

    2010-01-01

    Some major goals of the DUSEL THMCB experiment are to: (a) understand advective heat transfer and reactive transport in natural fractured rock settings, (b) determine rate constants for mineral dissolution and precipitation as a function of temperature in fractured rock, (c) provide an environment with large thermal gradients to understand links between microbial activity, nutrient supply and temperature, (d), quantify

  18. Vapor-compression heat pump system field tests at the TECH complex

    SciTech Connect

    Baxter, V.D.

    1985-01-01

    The Tennessee Energy Conservation in Housing (TECH) complex has been utilized since 1977 as a field test site for several novel and conventional heat pump systems for space conditioning and water heating. Systems tested include the Annual Cycle Energy System (ACES), solar assisted heat pumps (SAHP) both parallel and series, two conventional air-to-air heat pumps, an air-to-air heat pump with desuperheater water heater, and horizontal coil and multiple shallow vertical coil ground-coupled heat pumps (GCHP). A direct comparison of the measured annual performance of the test systems was not possible. However, a cursory examination revealed that the ACES had the best performance, however, its high cost makes it unlikely that it will achieve wide-spread use. Costs for the SAHP systems are similar to those of the ACES, but their performance is not as good. Integration of water heating and space conditioning functions with a desuperheater yielded significant efficiency improvement at modest cost. The GCHP systems performed much better for heating than for cooling and may well be the most efficient alternative for residences in cold climates. 27 references, 12 figures, 9 tables.

  19. Vapor compression heat pump system field tests at the TECH complex

    SciTech Connect

    Baxter, V.D.

    1985-01-01

    The Tennessee Energy Conservation In Housing (TECH) complex has been utilized since 1977 as a field test site for several novel and conventional heat pump systems for space conditioning and water heating. Systems tested include the Annual Cycle Energy System (ACES), solar assisted heat pumps (SAHP) both parallel and series, two conventional air-to-air heat pumps, an air-to-air heat pump with desuperheater water heater, and horizontal coil and multiple shallow vertical coil ground-coupled heat pumps (GCHP). A direct comparison of the measured annual performance of the test systems was not possible. However, a cursory examination revealed that the ACES had the best performance, however, its high cost makes it unlikely that it will achieve widespread use. Costs for the SAHP systems are similar to those of the ACES but their performance is not as good. Integration of water heating and space conditioning functions with a desuperheater yielded significant efficiency improvement at modest cost. The GCHP systems performed much better for heating than for cooling and may well be the most efficient alternative for residences in cold climates. 27 refs., 12 figs., 9 tabs.

  20. Effect of the properties of an intracavity heat spreader on second harmonic generation in vertical-external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Kim, Jun-Youn; Yoo, Jaeryung; Cho, Soohaeng; Kim, Ki-Sung; Kim, Gi Bum; Lee, Junho; Lee, Sang-Moon; Kim, Taek; Park, Yongjo

    2007-04-01

    We investigate the effect of the properties of an intracavity diamond heat spreader on the lasing performance of vertical-external-cavity surface-emitting lasers. We compared two intracavity diamonds with different average birefringences. When a polarization selective element is inserted into the cavity, the infrared output powers are reduced by 13% and 7%, respectively, for the samples with higher and lower average birefringences. The pump-power limited maximum green output powers were changed from 3to5.2W by rotating the samples with lower average birefringence. In order to explain the variation in green output power, the additional round-trip loss caused by diamond birefringence was analyzed theoretically and experimentally. We found that the loss can be reduced when axes of the birefringence are aligned to the axes of the polarization selective element.

  1. Comparison of DOE-2.1E with Energyplus and TRNSYS for Ground Coupled Residential Buildings in Hot anf Humid Climates Stage 2

    E-print Network

    Andolsun, S.; Culp, C.

    2011-01-01

    ESL-TR-11-12-09 COMPARISON OF DOE-2.1E WITH ENERGYPLUS AND TRNSYS FOR GROUND COUPLED RESIDENTIAL BUILDINGS IN HOT AND HUMID CLIMATES STAGE 2 “Literature Survey on Comparative Studies on Slab-on-grade and Basement Models of DOE-2, EnergyPlus... ............................................................................................................................. 4 Introduction ................................................................................................................................................... 4 1. Studies that compared DOE-2 with EnergyPlus...

  2. New CHF correlation scheme proposed for vertical rectangular channels heated from both sides in nuclear research reactors

    Microsoft Academic Search

    Y. Sudo; M. Kaminaga

    1993-01-01

    In this study, an investigation was carried out to identify the important parameters affecting critical heat flux (CHF) in rectangular channels, focusing on the effects of flow direction, channel inlet subcooling from 1 to 213 K, the channel outlet condition extending from subcooling of 0-74 K to quality of 0-1.0, pressure of 0.1 to 4 MPa, water mass flux of

  3. Steady and oscillatory laminar opposing mixed convection in a vertical channel of finite length subjected to symmetrical isothermal discrete heat sources

    NASA Astrophysics Data System (ADS)

    Martínez-Suástegui, Lorenzo; Treviño, César; Cajas, Juan Carlos

    2015-06-01

    Transient laminar opposing mixed convection in a gravity driven downward flow confined inside a vertical rectangular channel has been investigated, with both walls suddenly subjected to symmetrical isothermal heat sources over a finite portion of the channel walls. The unsteady two-dimensional Navier-Stokes and energy equations have been solved numerically for a wide parametric set. Studies are carried out for Reynolds numbers of 100 and 200 and several values of buoyancy strength or Richardson number. The effect of Reynolds number and opposing buoyancy on the temporal evolution of the overall flow structure, temperature field, and Nusselt number from the heated surfaces is investigated using fixed geometrical parameters and considering heat losses to the channel walls. In this parameter space, for a given Reynolds number and relatively small values of the buoyancy parameter, the transient process leads to a final symmetric or asymmetric steady-state. However, as the value of buoyancy strength increases, the flow and temperature fields become more complex and an oscillatory flow with a fundamental frequency sets in when a critical value of the Richardson number is reached. Numerical predictions show that the critical value of the Richardson number between the two regimes strongly depends on the value of the Reynolds number, and the time scales, natural frequencies, and phase-space portraits of flow oscillation are presented and discussed in detail. Stability of the symmetric response has been analyzed. The results include the effects of Prandtl number and heat losses to the channel walls on the evolution of the final flow and thermal responses.

  4. Downflow heat transfer in a heated ribbed vertical annulus with a cosine power profile (results from test series ECS-2c)

    NASA Astrophysics Data System (ADS)

    Anderson, J. L.; Condie, K. G.; Larson, T. K.

    1991-10-01

    Experiments designed to investigate downflow heat transfer in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2c series, which was a follow on series to the ECS-2b series, conducted specifically to provide additional data on the effect of different powers at the same test conditions, for use in evaluation of possible power effects on the aluminum temperature measurements. Electrical powers at 90, 100, and 110 percent of the power required to result in the maximum aluminum temperature at fluid saturation temperature were used at each set of test conditions previously used in the ECS-2b series. The ECS-2b series was conducted in the same test rig as the previous ECS-2b series.

  5. Velocity and temperature distribution of air in the boundary layer of a vertical plate for free-convective heat transfer 

    E-print Network

    Jullienne, Jean Maxime Jose

    1962-01-01

    . Ostrach, S. , An Analysis, of Laminar Free-Convection Flow and Heat Trends er about. a. Flat Plate Parallel to the Dire~ct on t ~t t. ~f7 pt * . WA X 8 P t Tlpl (~53 4. Eckert, E. R. G. , and. Soehngen, E. E. , Studies with the Zehnder-Mach... and Beckmann . using the Zender-Mach interferometer. H. Schuh (5), in 1948, , extended E. Pohlhausen's calculations by computing the velocity and . temperature distributions for large Prandtl numbers such as exist in oils. E. M. Sparrow and J. L. Gregg (6...

  6. A capital cost comparison of commercial ground-source heat pump systems

    SciTech Connect

    Rafferty, K.

    1996-04-10

    The ground-source heat pump industry is focusing a great deal of effort on reducing system first cost. For the most part, this effort has been directed at ground-coupled systems. This paper explores two other ground-source system types (hybrid and groundwater) and compares their costs to ground-coupled systems. Costs were developed for the three system types over a range of soil temperatures, well depths, building load characteristics and other parameters. Results show that reductions in capital cost of 20 to 80% can be achieved with hybrid and groundwater systems compared to ground-coupled systems.

  7. Vertical structure of aerosols and clouds in the atmospheres of Uranus and Neptune: Implications for their heat budgets

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Rages, Kathy; Bergstralh, Jay; Baines, Kevin; Wenkert, Daniel; Danielson, G. Edward

    1986-01-01

    Models possessing an upper haze layer of finite optical depth and a lower cloud layer of infinite optical depth at discrete altitudes are used to bound the wavelength-averaged phase integrals and bolometric albedos of Uranus and Neptune. The models differ in the assumed value of the particles single scattering phase function and the wavelength dependence of the haze optical depth. A range of phase functions, from the isotropic to those characterizing Titan, Jupiter, and Saturn atmosphere particles, are discussed. The results obtained imply that the meteorological regimes in the observable atmospheres of Uranus and Neptune may differ considerably; internal heat flux could play a much more important role for Neptune than for Uranus.

  8. Heat-transfer characteristics of an earth-probe model for a ground-source heat pump (experiments on forced-convection-boiling heat transfer in a vertical double tube: The case of small flow rates)

    Microsoft Academic Search

    Junji Nishioka; Hiromu Sugiyama; Takakage Arai

    1994-01-01

    An experimental investigation was conducted to determine the heat-transfer characteristics of HCFC-22 for a two-phase double tube connected to a heat pump. This study focused on the forced-convection-boiling heat transfer at small flow rates in a double tube. It was clarified that the quality at the dryout point increases as mass velocity increases, and that the heat-transfer coefficient of two-phase

  9. Heat-transfer characteristics of an earth-probe model for a ground-source heat pump (experiments on forced-convection-boiling heat transfer in a vertical double tube: The case of small flow rates)

    SciTech Connect

    Nishioka, Junji; Sugiyama, Hiromu; Arai, Takakage

    1994-07-01

    An experimental investigation was conducted to determine the heat-transfer characteristics of HCFC-22 for a two-phase double tube connected to a heat pump. This study focused on the forced-convection-boiling heat transfer at small flow rates in a double tube. It was clarified that the quality at the dryout point increases as mass velocity increases, and that the heat-transfer coefficient of two-phase flow is about 30 times as large as that of the liquid single-phase laminar flow. Furthermore, it was found that the heat-transfer performance of the double tube is superior to that of a single tube.

  10. Effects of Surface Heat Flux Anomalies on Stratification, Convective Growth and Vertical Transport within the Saharan Boundary Layer

    NASA Astrophysics Data System (ADS)

    Huang, Qian; Marsham, John; Parker, Doug; Tian, Wenshou; Grams, Christian; Cuesta, Juan; Flamant, Cyrille

    2010-05-01

    The very large surface sensible and very low latent heat fluxes in the Sahara desert lead to its unusually deep, almost dry-adiabatic boundary layer, that often reaches 6 km. This is often observed to consist of a shallow convective boundary layer (CBL) with a near neutral residual layer above (the Saharan Residual Layer, or SRL). It has been shown that the SRL can be both spatially extensive and persist throughout the day. Multiple near-neutral layers are frequently observed within the SRL, or within the SAL, each with a different water vapour and/or dust content, and each separated by a weak lid (e.g., Figure 1). A local maximum in not only relative humidity, but also water vapour mixing ratio (WVMR) is often seen at the top of the SRL or SAL. This structure suggests that in some locations, at some times, convection from the surface is mixing the full depth of the Saharan boundary layer, but in most locations and times this is not the case, and varying horizontal advection leads to the multiple layering observed. During the GERBILS (GERB Intercomparison of Longwave and Shortwave radiation) field campaign in the Sahara, coherent couplings were observed between surface albedo, CBL air temeperatures and CBL winds. Using two cases based on observations from GERBILS, large eddy model (LEM) simulations have been used to investigate the effects of surface flux anomalies on the growth of the summertime Saharan CBL into the Saharan Residual layer (SRL) above, and transport from the CBL into the SRL. Hot surface anomalies generated updraughts and convergence in the CBL that increased transport from the CBL into the SRL. The induced subsidence in regions away from the anomalies inhibited growth of the CBL there. If the domain-averaged surface fluxes were kept constant this led to a shallower, cooler CBL. If fluxes outside the anomalies were kept constant, so that stronger anomalies led to increased domain-averaged fluxes, this gave a warmer, shallower CBL. These effects were larger for wider, stronger anomalies, with low winds. These LEM simulations show that mesoscale variations in surface fluxes can contribute to both inhibiting the growth of the Saharan CBL into the SRL, and generating layerings within the SRL.

  11. Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997

    SciTech Connect

    Allan, M.L.

    1997-11-01

    Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.

  12. Oscillatory MHD Convective Flow of Second Order Fluid Through Porous Medium in a Vertical Rotating Channel in Slip-Flow Regime with Heat Radiation

    NASA Astrophysics Data System (ADS)

    Garg, B. P.; Singh, K. D.; Bansal, A. K.

    2015-02-01

    An analysis of an oscillatory magnetohydrodynamic (MHD) convective flow of a second order (viscoelastic), incompressible, and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel porous plates is presented. The two porous plates with slip-flow condition and the no-slip condition are subjected respectively to a constant injection and suction velocity. The pressure gradient in the channel varies periodically with time. A magnetic field of uniform strength is applied in the direction perpendicular to the planes of the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature of the plate with no-slip condition is non-uniform and oscillates periodically with time and the temperature difference of the two plates is assumed high enough to induce heat radiation. The entire system rotates in unison about the axis perpendicular to the planes of the plates. Adopting complex variable notations, a closed form solution of the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters of the problem. The velocity, temperature and the skin-friction in terms of its amplitude and phase angle have been shown graphically to observe the effects of the viscoelastic parameter ?, rotation parameter ?, suction parameter ? , Grashof number Gr, Hartmann number M, the pressure A, Prandtl number Pr, radiation parameter N and the frequency of oscillation ? .

  13. Analysis of hyperbolic signatures from small discontinuities using an UWB ground-coupled radar: FDTD simulations and field experiments

    NASA Astrophysics Data System (ADS)

    Sagnard, Florence; Tebchrany, Elias; Baltazart, Vincent

    2013-04-01

    Ground penetrating radar (GPR) is a well-known non-destructive technique based on electromagnetic wave propagation that is able to detect by reflection or scattering of waves dielectric discontinuities in the underground. Our application is mainly concerned with civil engineering to perform supervision, inventory, and soil characterization. Because the air-coupled radar suffers from a significant reflection at the ground interface that reduces energy transfer of electromagnetic radiation in the sub-surface and penetration depth, we have developed an ultra-wide band (UWB) ground-coupled radar made of a pair of partially shielded compact planar bowtie slot antennas. As the antenna dimension (36*23 cm2) is close to the A4 sheet size, the maturity of the microstrip technology has allowed to design a particular geometry on the FR4 substrate (h=1.5 mm) which is able to operate at frequencies from 460 MHz to beyond 4 GHz in air. Contrary to a commercial GPR where details on antenna design are not available, it appears here possible to know and control the radiation characteristics and develop full-wave FDTD modeling that can represent field experiments for comparisons and analyses. The objective of this work is to improve, by means of a parametric study, the knowledge of physical phenomena involved in dielectric polarization when waves interact with buried discontinuities and particularly cracks, pipes, delaminations that can be distinguished by their shape, size, dielectric contrast with the surrounding medium, orientation relative to the electric field… Thus, we have first characterized by FDTD modeling and field measurements in a wet sand the radar link in two perpendicular polarizations (parallel and mirror) in the presence of a common soil (epsilon'=5.5, sigma=0.01 S/m) considering variable offsets. Afterwards, we have studied and analyzed the hyperbola signatures generated by the presence of buried canonical objects (pipes, strips) with several dielectric properties (dielectric and conductive) in a wet sand with a small lateral dimension (less than 20 mm) in both polarizations. Comparisons with FDTD simulations including the detailed structure of the antennas appear promising as they have allowed to interpret the measurements and take advantage of signal polarization to extract information associated with the discontinuities. After cluster removal using classical data processing (SVD, median value substraction…), the analytical model based on the ray theory and including the antenna size has allowed to first analyze the hyperbola responses. This study is supposed to prepare the development of data processing associated with B-scans to extract quantitative information from the electromagnetic probing of the subsurface in a very large frequency band.

  14. Analysis of solar aided heat pump systems with seasonal thermal energy storage in surface tanks

    Microsoft Academic Search

    R. Yumruta?; M. Ünsal

    2000-01-01

    Annual periodic performance of a solar assisted ground-coupled heat pump space heating system with seasonal energy storage in a hemispherical surface tank is investigated using analytical and computational methods. The system investigated employs solar energy collection and dumping into a seasonal surface tank throughout the whole year with extraction of thermal energy from the tank for space heating during the

  15. The Maximum Drop-Height of a Droplet in a Vertical Countercurrent Water-Air Heat and Moisture Exchange Tower Attached to a Main Fan Diffuser in a Coal Mine

    NASA Astrophysics Data System (ADS)

    Chen, S.; Cui, H.; Wang, H.; Zhao, J.

    2014-10-01

    A vertical countercurrent water-air heat and moisture exchange tower attached to a main fan diffuser is designed. To reduce water loss blown away by the airflow from the exchange tower, the forces acting on droplets are analysed. Droplet motion may be classified under four conditions: (1) downward initial acceleration; (2) upward initial acceleration; (3) droplet blown away by airflow; (4) droplet suspension. With droplet break-up neglected, a general equation for the maximum droplet drop-height is presented and numerical calculations are performed. Equations for the maximum drop-height under Conditions 3 and 4 are deduced, and the equation for Condition 3 is applied to an engineering case study. The effect of air velocity on the maximum drop-height is more significant than that of other factors. The conclusions provide a novel approach to optimizing the design of vertical countercurrent water-air heat and moisture exchange towers attached to main fan diffusers.

  16. Laminar Free Convection from Vertical Thin Needles

    Microsoft Academic Search

    Jai P. Narain; Mahinder S. Uberoi

    1972-01-01

    A similarity solution is obtained for the problem of free-convection heat transfer over a thin vertical needle with uniform heat flux at the surface. A few errors in previous papers on “isothermal” needles have been modified.

  17. Measured water heating performance of a vertical-bore water-to-water ground source heat pump (WW-GSHP) for domestic water heating over twelve months under simulated occupancy loads

    SciTech Connect

    Ally, Moonis Raza [ORNL; Munk, Jeffrey D [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL

    2014-01-01

    This paper presents monthly performance metrics of a 5.275 kW (1.5 ton) WW-GSHP providing 227 L day-1 domestic hot water at 49 C. Daily water use is simulated as stipulated in the Building America Research Benchmark Definition capturing the living habits of the average U.S household. The 94.5m vertical-bore ground loop is shared with a separate GSHP for space conditioning the 251m2 residential home. Data on entering water temperatures, energy extracted from the ground, delivered energy, compressor electricity use, COP, WW-GSHP run times, and the impact of fan and pump energy consumption on efficiency are presented for each month. Factors influencing performance metrics are highlighted.

  18. TECHNICAL AND MARKET RESULTS OF MAJOR U.S. GEOTHERMAL HEAT PUMP PROGRAMS

    Microsoft Academic Search

    P. J. Hughes; L. Pratsch

    The term geothermal heat pumps (also known as GHPs, ground-coupled heat pumps, and GeoExchange systems) refers to a family of systems that meet heating, cooling, and water heat- ing needs while using 20 - 40% less energy than conventional space-conditioning systems. The GHP industry evolved from a few refinements in commercially available water-source heat pump and natural gas distribution pipe

  19. The influence of the borehole short-time response on ground source heat pump system efficiency

    Microsoft Academic Search

    Vincent Partenay; Peter Riederer; Tristan Salque; Etienne Wurtz

    2011-01-01

    Ground coupled heat pump systems can offer high energy efficiency for heating and cooling of buildings.The coupling of the ground loop with system and building represents a complex system and system performances can vary over long periods, in the range of 10–15 years due to the charge or discharge of the ground loop. In order to correctly concept, size and

  20. Numerical analysis and experimental validation of heat transfer in ground heat exchangers in alternative operation modes

    Microsoft Academic Search

    P. Cui; H. Yang; Z. Fang

    2008-01-01

    A finite element numerical model has been developed for the simulation of the ground heat exchangers (GHEs) in alternative operation modes over a short time period for ground-coupled heat pump applications. Comparisons between the numerical and analytical results show that the finite line-source model is not capable of modeling the GHEs within a few hours because of the line-source assumption.

  1. Vertical Farm

    NSDL National Science Digital Library

    2004-01-01

    With the continued growth of the human population of the Earth, there is increasing concern with the planet's ability to provide sustenance for all of its inhabitants. This compelling website by Dickson Despommier and his colleagues at Columbia University provides a worthy alternative to other forms of agriculture: the vertical farm. As Dr. Despommier notes on the site, "..they offer the promise of urban renewal, sustainable production of a safe and varied food supply (year-round crop production), and the eventual repair of ecosystems that have been sacrificed for horizontal farming." The site offers a great deal of information about these vertical farms, a detailed essay on the importance of such farms, a number of potential designs, and a discussion forum. Finally, there are a number of plans that indicate how this type of farm might be effectively created and sustained.

  2. Today's ground source heat pumps

    SciTech Connect

    Bose, J.E.

    1993-01-01

    Ground source heat pumps are one of the nation's fastest growing businesses in terms of increased sales of equipment as reported by water source heat pump manufacturers. The success can be attributed in part to these heat pump's reputation as a cost saving system and more recently as an environmentally sound concept. Engineers having an interest in ground source technology come from a large and diverse audience consisting of those who have heard about ground source systems and are contemplating entering the business and those who are experienced and looking to broaden their application base. This article discusses the water source heat pump and its benefits, the commercial Water Loop Heat Pump (WLHP), the ground source heat pump, the commercial Closed Loop/Ground Coupled WLHP, designing a ground heat exchanger, information available for design, and successful systems.

  3. Thermal Analysis on MonoBlock Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data against Inlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Masahiro Shiotsu; Nobuaki Noda

    2006-01-01

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149 mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d, of 10 mm and the carbon armor

  4. Thermal Analysis on Flat-Plate-Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data Against Inlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Masahiro SHIOTSU

    2006-01-01

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d ,o f 10mm and the carbon armor outer

  5. Vertical Profiles of Latent Heat Release and Their Retrieval for TOGA COARE Convective Systems Using a Cloud Resolving Model, SSM/I, and Ship-borne Radar Data

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Lang, S.; Simpson, J.; Olson, W. S.; Johnson, D.; Ferrier, B.; Kummerow, C.; Adler, R.

    1999-01-01

    Latent heating profiles associated with three (TOGA COARE) Tropical Ocean and Global Atmosphere Coupled Ocean Atmosphere Response Experiment active convective episodes (December 10-17 1992; December 19-27 1992; and February 9-13 1993) are examined using the Goddard Cumulus Ensemble (GCE) Model and retrieved by using the Goddard Convective and Stratiform Heating (CSH) algorithm . The following sources of rainfall information are input into the CSH algorithm: Special Sensor Microwave Imager (SSM/1), Radar and the GCE model. Diagnostically determined latent heating profiles calculated using 6 hourly soundings are used for validation. The GCE model simulated rainfall and latent heating profiles are in excellent agreement with those estimated by soundings. In addition, the typical convective and stratiform heating structures (or shapes) are well captured by the GCE model. Radar measured rainfall is smaller than that both estimated by the GCE model and SSM/I in all three different COARE IFA periods. SSM/I derived rainfall is more than the GCE model simulated for the December 19-27 and February 9-13 periods, but is in excellent agreement with the GCE model for the December 10-17 period. The GCE model estimated stratiform amount is about 50% for December 19-27, 42% for December 11-17 and 56% for the February 9-13 case. These results are consistent with large-scale analyses. The accurate estimates of stratiform amount is needed for good latent heating retrieval. A higher (lower) percentage of stratiform rain can imply a maximum heating rate at a higher (lower) altitude. The GCE model always simulates more stratiform rain (10 to 20%) than the radar for all three convective episodes. SSM/I derived stratiform amount is about 37% for December 19-27, 48% for December 11-17 and 41% for the February 9-13 case. Temporal variability of CSH algorithm retrieved latent heating profiles using either GCE model simulated or radar estimated rainfall and stratiform amount is in good agreement with that diagnostically determined for all three periods. However, less rainfall and a smaller stratiform percentage estimated by radar resulted in a weaker (underestimated) latent heating profile and a lower maximum latent heating level compared to those determined diagnostically. Rainfall information from SSM/I can not retrieve individual convective events due to poor temporal sampling. Nevertheless, this study suggests that a good 4r, rainfall retrieval from SSM/I for a convective event always leads to a good latent heating retrieval. Sensitivity testing has been performed and the results indicate that the SSM/I derived time averaged stratiform amount may be underestimated for December 19-27. Time averaged heating profiles derived from SSM/I, however, are not in bad agreement with those derived by soundings for the December 10-17 convective period. The heating retrievals may be more accurate for longer time scales provided there is no bias in the sampling.

  6. Boiling induced nanoparticle coating and its effect on pool boiling heat transfer on a vertical cylindrical surface using CuO nanofluids

    NASA Astrophysics Data System (ADS)

    Hegde, Ramakrishna N.; Rao, Shrikantha S.; Reddy, R. P.

    2012-09-01

    Experiments were performed to study boiling induced nanoparticle coating and its influence on pool boiling heat transfer using low concentrations of CuO- nanofluid in distilled water at atmospheric pressure. To investigate the effect of the nanoparticle coated surface on pool boiling performance, two different concentrations of CuO nanofluids (0.1 and 0.5 g/l) were chosen and tests were conducted on a clean heater surface in nanofluid and nanoparticle coated surface in pure water. For the bare heater tested in CuO nanofluid, CHF was enhanced by 35.83 and 41.68 % respectively at 0.1 and 0.5 g/l concentration of nanofluid. For the nanoparticle coated heater surface obtained by boiling induced coating using 0.1 and 0.5 g/l concentration of nanofluid and tested in pure water, CHF was enhanced by 29.38 and 37.53 % respectively. Based on the experimental investigations it can be concluded that nanoparticle coating can also be a potential substitute for enhancing the heat transfer in pure water. Transient behaviour of nanofluid was studied by keeping heat flux constant at 1,000 and 1,500 kW/m2 for 90 min in 0.5 g/l concentration. The boiling curve shifted to the right indicating degradation in boiling heat transfer due to prolonged exposure of heater surface to nanofluid. Experimental outcome indicated that pool boiling performance of nanofluid could be a strong function of time and applied heat flux. The longer the duration of exposure of the heater surface, the higher will be the degradation in heat transfer.

  7. Thermal Analysis on Mono-Block Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data against Inlet Subcooling in Short Vertical Tube

    NASA Astrophysics Data System (ADS)

    Hata, Koichi; Shiotsu, Masahiro; Noda, Nobuaki

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149 mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d, of 10 mm and the carbon armor outer diameter, D, of 26 and 33 mm were numerically analyzed based on the measured CHFs and HTCs at the inlet pressure of around 800 kPa. The numerical solutions were also compared with those for the Flat-plate type divertor, which were numerically analyzed for the divertor with the cooling tube diameter d=10 mm and the divertor width, w, ranging from 16 to 30 mm. It is confirmed that the ratio of the one-side heating CHF data, qcr,inc, to the uniform heating CHF data, qcr,sub, can be represented as the simple equation based on the numerical solutions. The values of the qcr,inc for L=50, 100 and 150 mm were estimated with various D/d and w/d at higher pressures.

  8. Year round experimental study on a constant temperature and humidity air-conditioning system driven by ground source heat pump

    Microsoft Academic Search

    X. Yu; R. Z. Wang; X. Q. Zhai

    2011-01-01

    Numerous studies about the ground source heat pump building heating and cooling systems have been constructed in office building, hotel, residential building and school et al. However, few researches about the constant temperature and humidity air-conditioning system driven by ground-coupled heat pumps were carried out. In this paper, a constant temperature and humidity air-conditioning system driven by ground source heat pump

  9. Downflow dryout in a heated ribbed vertical annulus with a cosine power profile (Results from test series ECS-2, WSR, and ECS-2cE)

    SciTech Connect

    Larson, T.K.; Anderson, J.L.; Condie, K.G.

    1990-12-01

    Experiments designed to investigate surface dryout in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2, WSR, and ECS-2cE series of tests. These experiments were conducted to examine the onset of wall thermal excursion for a range of flow, inlet fluid temperature, and annulus outlet pressure. Hydraulic boundary conditions on the test section represent flowrates (0.1--1.4 1/s), inlet fluid temperatures (293--345 K), and outlet pressures (-18--139.7 cm of water relative to the bottom of the heated length (61--200 cm of water relative to the bottom of the lower plenum)) expected to occur during the Emergency Coolant System (ECS) phase of postulated Loss-of-Coolant Accident in a production reactor. The onset of thermal excursion based on the present data is consistent with data gathered in test rigs with flat axial power profiles. The data indicate that wall dryout is primarily a function of liquid superficial velocity. Air entrainment rate was observed to be a strong function of the boundary conditions (primarily flowrate and liquid temperature), but had a minor effect on the power at the onset of thermal excursion for the range of conditions examined. 14 refs., 33 figs., 13 tabs.

  10. Hybrid Heat Pumps Using Selective Water Sorbents (SWS)

    SciTech Connect

    Ally, M. R.

    2006-11-30

    The development of the ground-coupled and air-coupled Heating Ventilation and Air-Conditioning (HVAC) system is essential in meeting the goals of Zero Energy Houses (ZEH), a viable concept vigorously pursued under DOE sponsorship. ORNL has a large Habitat for Humanity complex in Lenoir City where modem buildings technology is incorporated on a continual basis. This house of the future is planned for lower and middle income families in the 21st century. The work undertaken in this CRADA is an integral part of meeting DOE's objectives in the Building America program. SWS technology is a prime candidate for reducing the footprint, cost and improve the performance of ground-coupled heat pumps. The efficacy of this technique to exchange energy with the ground is a topic of immense interest to DOE, builders and HVAC equipment manufacturers. If successful, the SWS concept will become part of a packaged ZEH kit for affordable and high-end houses. Lennox Industries entered into a CRADA with Oak Ridge National Laboratory in November 2004. Lennox, Inc. agreed to explore ways of using Selective Water Sorbent materials to boost the efficiency of air-coupled heat pumps whereas ORNL concentrated on ground-coupled applications. Lennox supplied ORNL with heat exchangers and heat pump equipment for use at ORNL's Habitat for Humanity site in Lenoir City, Tennessee. Lennox is focused upon air-coupled applications of SWS materials at the Product Development and Research Center in Carrollton, TX.

  11. Vertical dynamics Spiral structure

    E-print Network

    Kruit, Piet van der

    Outline Vertical dynamics Spiral structure The Hubble type of the Galaxy STRUCTURE OF GALAXIES 7;Outline Vertical dynamics Spiral structure The Hubble type of the Galaxy Outline Vertical dynamics van der Kruit, Kapteyn Astronomical Institute Structure of galaxy disks #12;Outline Vertical dynamics

  12. Investigation of direct expansion in ground source heat pumps

    NASA Astrophysics Data System (ADS)

    Kalman, M. D.

    A fully instrumented subscale ground coupled heat pump system was developed, and built, and used to test and obtain data on three different earth heat exchanger configurations under heating conditions (ground cooling). Various refrigerant flow control and compressor protection devices were tested for their applicability to the direct expansion system. Undistributed Earth temperature data were acquired at various depths. The problem of oil return at low evaporator temperatures and low refrigerant velocities was addressed. An analysis was performed to theoretically determine what evaporator temperature can be expected with an isolated ground pipe configuration with given length, pipe size, soil conditions and constant heat load. Technical accomplishments to data are summarized.

  13. Vertical constituent transport in the mesosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Summers, Michael E.; Bevilacqua, Richard M.; Deland, Matthew T.; Allen, Mark

    1987-01-01

    Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for O and O3, below the mesopause, the divergences of their associated fluxes are modest, with at most a factor of 2 effect on the concentrations of O and O3 for measured variability in gravity wave activity. Comparison of Solar Mesosphere Explorer (SME) O3 data with model results reinforces the conclusions of slow vertical mixing in the upper mesosphere as a consequence of the reduced HO(x) catalytic loss of odd oxygen. The changes in chemical rate constants recommended by Rusch and Eckman (1985), in conjunction with slow vertical mixing, yield good agreement with SME O3 data. The slow vertical mixing deduced in this study is consistent with upper limits obtained from studies of the mesospheric heat budget and could be construed as evidence for an advectively controlled mesosphere. A comparison of the vertical eddy diffusion coefficients for momentum stresses, constituent transport, and heat transport suggests that the eddy Prandtl number must be of order 10.

  14. Solr assisted heat pump research and development program in the United States

    SciTech Connect

    Andrews, J W

    1980-01-01

    A review of the historical progress and current status of the solar assisted heat pump research and development, supported by the United States Department of Energy, is presented. Much of this work has had as its focus the need for a better source of auxiliary or backup heat than the electric resistance which has generally been assumed in computer simulations of these systems. The two leading candidates are the use of the ground as an alternate heat source/sink or storage element (ground coupling) and the use of fossil fuel burned on site (the bivalent system). The United States program has emphasized ground coupling. Much of the analytical work and heat pump development is applicable to bivalent systems, and some results of this work are discussed. Project descriptions and technical accomplishments for the currently active projects are presented.

  15. Field observations and numerical models of GPR response from vertical pavement cracks

    NASA Astrophysics Data System (ADS)

    Diamanti, Nectaria; Redman, David

    2012-06-01

    High resolution ground-coupled GPR is useful for determining thickness, deterioration, jointing and cracks in pavements. Although only millimetres in width, vertical cracks can present a significant target in reflection profiles. On composite pavements, consisting of asphalt over concrete, we have observed responses at locations above joints in the underlying concrete that we attribute to cracks within the asphalt layer. On some asphalt pavement, we observed significantly stronger diffraction and waveguide effects responses at a 250 MHz centre frequency rather than at 1000 MHz, despite the small crack apertures. Using numerical modelling we show the importance of crack filling material, crack aperture, crack height, asphalt conductivity and the GPR centre frequency on the observed response. Our observations and models clearly show the potential of GPR to detect and characterise vertical cracks. We recommend a multi-frequency approach to GPR surveys of pavement: high frequency for crack characterisation and lower frequency for crack detection.

  16. Hydrometeor size distributions retrieved from vertical pointing UHF and S-band profilers during the TRMM ground validation program

    Microsoft Academic Search

    Christopher R. Williams; Kenneth S. Gage

    2000-01-01

    With their high vertical and temporal resolution, vertically-pointing profilers offer valuable information about the vertical structure of precipitating cloud systems. The observed vertical structure of the precipitating cloud is related to the latent heating profile in the cloud system. The different precipitation regimes (e.g., convective, stratiform, and transitional precipitation) can be identified by diagnosing the profiler resolved vertical structure of

  17. Vertical Map Storage.

    ERIC Educational Resources Information Center

    Perry, Joanne M.

    1982-01-01

    Discusses the superiority of vertical filing of maps in compressor-style vertical units over horizontal filing in drawers, emphasizing such factors as physical protection of the collection, ease of filing and retrieval, and efficient use of space. Disadvantages of vertical filing are also reviewed. (Author/JL)

  18. Thermally optimum spacing of vertical, natural convection cooled, parallel plates

    Microsoft Academic Search

    A. Bar-Cohen; W. M. Rohsenow

    1981-01-01

    Vertical two-dimensional channels formed by parallel plates or fins are a frequently encountered configuration in natural convection cooling in air of electronic equipment. In connection with the complexity of heat dissipation in vertical parallel plate arrays, little theoretical effort is devoted to thermal optimization of the relevant packaging configurations. The present investigation is concerned with the establishment of an analytical

  19. Vertical electromagnetic profiling (VEMP)

    Microsoft Academic Search

    Lytle

    1984-01-01

    Vertical seismic profiling (VSP) is based upon reception measurements performed in a borehole with a source near the ground surface. This technology has seen a surge in application and development in the last decade. The analogous concept of vertical electromagnetic profiling (VEMP) consists of reception measurements performed in a borehole with a source near the ground surface. Although the electromagnetic

  20. Geothermal direct-heat utilization assistance. Quarterly project progress report, October--December 1993

    SciTech Connect

    Not Available

    1993-12-31

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on (1) compilation of data on low-temperature resources and (2) evaluation of groundwater vs. ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  1. Heat transfer system

    DOEpatents

    McGuire, Joseph C. (Richland, WA)

    1982-01-01

    A heat transfer system for a nuclear reactor. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  2. Heat transfer system

    DOEpatents

    Not Available

    1980-03-07

    A heat transfer system for a nuclear reactor is described. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  3. Vertical electromagnetic profiling (VEMP)

    SciTech Connect

    Lytle, R.J.

    1984-08-01

    Vertical seismic profiling (VSP) is based upon reception measurements performed in a borehole with a source near the ground surface. This technology has seen a surge in application and development in the last decade. The analogous concept of vertical electromagnetic profiling (VEMP) consists of reception measurements performed in a borehole with a source near the ground surface. Although the electromagnetic concept has seen some application, this technology has not been as systematically developed and applied as VSP. Vertical electromagnetic profiling provides distinct and complementary data due to sensing different physical parameters than seismic profiling. Certain of the advantages of VEMP are presented. 28 references, 7 figures.

  4. Vertical axis wind turbine

    SciTech Connect

    Kutcher, H.R.

    1984-05-15

    A Darrieus-type vertical axis wind turbine is disclosed which includes a vertically extending rotor tube mounted on a support structure with two or three rotor blades of troposkein configuration on the rotor tube for rotating the tube in response to wind energy and thereby drive a generator to produce electrical power. The turbine includes an erection hinge which permits assembly of the rotor tube and blades at close to ground level followed by upward hinging of the rotor assembly to a vertical position. It also includes a system for automatically lubricating the top bearing upon erection and a system for visually tensioning the guy cables.

  5. Vertical Line Test

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students try to connect given points on a graph in a way that they will pass the vertical line test. If the points can't be made to pass the vertical line test, the student must adjust the points so they will pass the test. This activity allows students to explore the vertical line test for functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  6. Enhancement of Condensation on a Vertical Plate

    NASA Astrophysics Data System (ADS)

    Chu, Rencai; Hatanaka, Tsutomu; Nishio, Shigefumi

    In previous study, the characteristic of the condensation heat transfer on the dispersed vertical surface were investigated experimentally for the application of the finned surface to the thermoelectric generator utilizing boiling and condensation as the electrodes of the thermoelectric module. A prediction model for this diapered finned surface was proposed, based on Adamek-Webb model of the condensation on a finned tube. In this study, a condensation heat transfer experiment on a vertical dispersed finned surfaces using FC5312 was carried out, in order to enhance the condensation heat transfer coefficient by optimizing the fin size on a dispersed heat transfer surface. The object of the experiment was limited to the rectangular fin with the height of 3 mm. Experimental parameters were the temperature difference, the fin groove width, the fin thickness and the dispersing size on the vertical direction. As the results, it was found from the experiment that the dependence of the condensation heat transfer coefficient on the dispersed size is controlled by the fin groove width. That is, the condensation heat transfer coefficient will increase for a smaller fin groove width and will decrease for a larger fin groove width, with decreasing of the dispersing size. Moreover, there is an optimum fin thickness at which the condensation heat transfer coefficient becomes the maximum in the case of constant fin groove width for both size of the fin groove width. This effect of the fin thickness is more significant for the smaller fin groove width. Further, the prediction values exhibit a good agreement with the experimental data in the present experiment.

  7. Vertical neck lifting.

    PubMed

    Jacono, Andrew A; Talei, Benjamin

    2014-05-01

    The authors' vertical neck lifting procedure is an extended deep plane facelift, which elevates the skin and SMAS-platysma complex as a composite unit. The goal is to redrape cervicomental laxity vertically onto the face rather than laterally and postauricularly. The authors consider this an extended technique because it lengthens the deep plane flap from the angle of the mandible into the neck to release the cervical retaining ligaments that limit platysmal redraping. This technique does not routinely use midline platysmal surgery because it counteracts the extent of vertical redraping. A majority of aging face patients are good candidates for this procedure in isolation, but indications for combining vertical neck lifting with submental surgery are elucidated. PMID:24745389

  8. Vertical sleeve gastrectomy

    MedlinePLUS

    ... smaller stomach is about the size of a banana. It limits the amount of food you can ... staples. This creates a long vertical tube or banana-shaped stomach. The surgery does not involve cutting ...

  9. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P. (Walnut Creek, CA); Sommargren, Gary E. (Santa Cruz, CA); McConaghy, Charles F. (Livermore, CA); Krulevitch, Peter A. (Pleasanton, CA)

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  10. EXPERIMENTAL COMPARISON OF FOUR BOREHOLE HEAT EXCHANGERS

    Microsoft Academic Search

    J. ACUÑA; B. PALM

    2008-01-01

    The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a closed U-pipe loop in a vertical borehole. This fluid transports the heat from the rock to the ground source heat pump evaporator. The quality of the heat exchange with the ground and the necessary pumping power to

  11. Fast reactor power plant design having heat pipe heat exchanger

    Microsoft Academic Search

    Paul R. Huebotter; George A. McLennan

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water\\/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the

  12. Fast reactor power plant design having heat pipe heat exchanger

    Microsoft Academic Search

    P. R. Huebotter; G. A. McLennan

    1984-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water\\/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the

  13. Vertical emitting aperture nanoantennas.

    PubMed

    Yaacobi, Ami; Timurdogan, Erman; Watts, Michael R

    2012-05-01

    Herein we propose, theoretically investigate, and numerically demonstrate a compact design for a vertical emitter at a wavelength of 1.5 ?m based on nanophotonic aperture antennas coupled to a dielectric waveguide. The structure utilizes a plasmonic antenna placed above a Si3N4 waveguide with a ground plane for breaking the up-down symmetry and increasing the emission efficiency. Three-dimensional (3-D) finite-difference time-domain (FDTD) simulations reveal that up to 60% vertical emission efficiency is possible in a structure only four wavelengths long with a 3 dB bandwidth of over 300 nm. PMID:22555702

  14. INCORPORATION OF GROUNDWATER FLOW INTO NUMERICAL MODELS AND DESIGN MODELS

    E-print Network

    -coupled, ground-source heat pumps, groundwater, heat pump, heat exchanger, heat transfer, numerical models-loop ground-coupled heat exchangers. Green and Perry (1961) demonstrated that the value of effective thermal on the design and performance of vertical closed-loop ground heat exchangers. Based on the investigation results

  15. Vertical shaft windmill

    NASA Technical Reports Server (NTRS)

    Grana, D. C.; Inge, S. V., Jr. (inventors)

    1983-01-01

    A vertical shaft has several equally spaced blades mounted. Each blade consists of an inboard section and an outboard section skew hinged to the inboard section. The inboard sections automatically adjust their positions with respect to the fixed inboard sections with changes in velocity of the wind. This windmill design automatically governs the maximum rotational speed of shaft.

  16. The effects of soil vertical discretization, soil thermal properties, and soil heat convection by liquid water transfer on the water and energy cycles in a coupled land-atmosphere model

    NASA Astrophysics Data System (ADS)

    Wang, Fuxing; Dufresne, Jean-Louis; Chéruy, Frédérique; Ducharne, Agnès

    2015-04-01

    The soil heat transfer is an important component in general circulation model (GCM), and accurate representation of subsurface thermodynamics is essential for earth system modeling. The accuracy of the soil thermodynamics simulation is affected by many factors: (1) the bottom boundary layer position used in numerical scheme; (2) the soil thermal property (heat capacity and thermal conductivity) parameterization; as well as (3) the physical processes considered in the model. However, the impact of their correct representation on the quality of the simulated climate is poorly documented, and the way state-of-the art land surface model (LSM) used for climate simulations account for them is highly variable. For instance bottom boundary layer position varies from 2 m to 10 m or even more (100 m), the parameterizations of the soil thermal properties not always account for the soil texture effects, and the soil heat convection process is neglected in most soil thermodynamics models. In this work, we revisited the soil thermodynamics model included in the ORCHIDEE LSM in order (1) to determine the soil bottom layer depth which allows for simulating the annual cycle of temperature; (2) to improve the parameterization of the soil thermal properties (thermal conductivity and heat capacity) by accounting for both soil moisture and soil texture effects on the soil thermal properties; (3) to take into account the heat generated by liquid water movement in soil thermodynamics. The developpement of the parameterizations has been done in a 1-D framework where the results of the Finite Difference Method have been compared to the analytical solution. Sensitivity experiments with the LMDZ-ORCHIDEE coupled model (atmosphere-land component of IPSL-CM model) have been then designed to evaluate the impact of the soil thermal properties and soil heat convection on the water and energy cycles of the land-atmosphere. Main results are: (1) the 8 meter soil depth is proposed as a minimum requirement for simulating the annual cycle of soil temperature; (2) the surface water and energy cycles are sensitive to the soil thermal property parameterization. A lower (higher) thermal inertia leads to smaller (larger) amplitude of surface soil heat flux. The soil temperature decreases (increases) with the decreasing (increasing) of soil heat diffusivity. The net radiation is also affected by soil thermal properties due to the variation of upward long-wave radiation (caused by surface temperature). The changing of net radiation is mainly compensated by the sensible heat flux. During the night, the air temperature is more affected by the soil thermal properties than that during the day. (3) The rain temperature is lower than the land surface temperature in most regions, which means that the rainfall cools the land surface. In daily or shorter (e.g., 3-Houly) time scales, the soil temperature (turbulent heat flux) varies about 0.05 K (+/- 6 W/m2) with the rainfall (its heat flux) equal 0-5mm/d (0-4 W/m2). The soil heat convection effects on surface turbulent heat fluxes are small (+/- 1 W/m2) on monthly scale.

  17. Vertical ionospheric sounding measurements

    Microsoft Academic Search

    W. F. Utlaut; T. N. Gautier

    1964-01-01

    This report presents data on the ionospheric perturbations resulting from the five 1962 high-altitude nuclear detonations, Star Fish, Check Mate, Blue Gill, King Fish, and Tight Rope, as obtained with sweep-frequency vertical-incidence ionosondes operated at the Islands of Maui, Tern (French Frigate Shoals), Midway, Wake (Star Fish only), Canton, Tutuila (American Samoa), and Tongatapu. The ionosondes at Midway and Tongataupu

  18. Vertical Motion Simulator

    NSDL National Science Digital Library

    The Vertical Motion Simulator (VMS), at the NASA Ames Research Center, is an advanced flight simulation facility. This Web site provides thorough descriptions of all of the VMS systems. The VMS is a full immersion environment, complete with customizable cockpit, controls, and instrumentation to give the appearance of any aerospace vehicle. One of its most intriguing characteristics is "out-the-window graphics." This allows the pilot to see computer generated imagery of real locations, so virtually everything is identical to the actual flying experience. Even aircraft that are still in the design stage can be simulated on the VMS.

  19. Vertical wind turbine

    SciTech Connect

    Danson, D.P.

    1988-08-16

    This patent describes a wind driven turbine of the vertical axis type comprising: (a) a support base; (b) a generally vertical column rotatably mounted to the support base; (c) upper and lower support means respectively mounted on the column for rotation therewith; wind driven blades connected between the upper and lower support means for rotation about the column and each blade being individually rotatable about a blade axis extending longitudinally through the blade to vary a blade angle of attach thereof relative to wind velocity during rotation about the column; and (e) control means for variably adjusting angles of attack of each blade to incident wind, the control means including a connecting rod means having drive means for rotating each blade about the associated blade axis in response to radial movement of the connecting rod means and control shaft pivotally mounted within the column and having a first shaft portion connected to the connecting rod means and a second shaft portion radially offset from the first shaft portion and pivotally connected to radially displace the first portion and thereby the connecting rod means to vary the blade angles of attack during rotation about the column.

  20. Heat-pipe Earth.

    PubMed

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics. PMID:24067709

  1. Modular tube bundle heat exchanger and geothermal heat pump system

    SciTech Connect

    Galiyano, M.J.; Wiggs, B.R.; Aspacher, J.T.

    1993-07-06

    An improved ground source heat pump system is described, comprising: an in-ground heat exchanger and a building heat exchanger coupled via conduits for refrigerant to at least one compressor and at least one expander, the compressor having at least one intake line and at least one discharge line, the compressor and the expander being coupled to the conduits such that the refrigerant is circulated in the conduits through pressure changes and corresponding temperature changes in the refrigerant, the in-ground heat exchanger comprising at least one modular tube bundle comprising a plurality of substantially horizontally oriented subterranean tubes, buried in a substantially planar vertical array for installation along substantially vertical walls of at least one that is backfilled for setting the array in thermal engagement with the earth, said at least one bundle having a top and bottom displaced vertically from one another, and the refrigerant being subjected to phase change in the conduits.

  2. Measurement of ultralow vertical emittance using a calibrated vertical undulator

    NASA Astrophysics Data System (ADS)

    Wootton, K. P.; Boland, M. J.; Rassool, R. P.

    2014-11-01

    Very few experimental techniques are useful for the direct observation of ultralow vertical emittance in electron storage rings. In this work, quantitative measurements of ultralow (pm rad) electron beam vertical emittance using a vertical undulator are presented. An undulator radiation model was developed using the measured magnetic field of the APPLE-II type undulator. Using calibrated experimental apparatus, a geometric vertical emittance of ?y=0.9 ±0.3 pm rad has been observed. These measurements could also inform modeling of the angular distribution of undulator radiation at high harmonics, for proposed diffraction-limited storage ring light sources.

  3. Supersaturation Development in a Vertical-Flow Thermal Diffusion Chamber

    Microsoft Academic Search

    P. C. Mahata; D. J. Alofs; A. M. Sinnarwalla

    1973-01-01

    Analytical expressions are derived for temperature and vapor pressure profiles in a vertical-plate, steady-flow, thermal diffusion chamber designed to count cloud condensation nuclei. The influence of longitudinal diffusion of heat and water vapor on the supersaturation rise time is shown to be quite significant at low sample velocities. The effect of different velocity profile shapes is also investigated.

  4. A parametric model of vertical eddy fluxes in the atmosphere

    Microsoft Academic Search

    Jean-François Louis

    1979-01-01

    A scheme for the representation of the vertical eddy fluxes of heat, momentum and water vapour in a forecast model is presented. An important feature of the scheme is the dependence of the diffusion coefficients on the static stability of the atmosphere. Two tests are presented, using the scheme in a one-dimensional model: the simulation of the diurnal cycle, and

  5. Comparison of horizontal and vertical launch into orbit

    Microsoft Academic Search

    Frederick W. Boltz

    1987-01-01

    The analysis method used in the present comparative study of the approximate motion and heating of a transatmospheric vehicle employing either horizontal or vertical launch into LEO is based on Chapman's (1959) Z-function transformation of the equations of motion with the assumption of an exponential atmosphere. These equations, which have been modified to include the effects of thrusting with mass

  6. Coupled resonator vertical cavity laser

    SciTech Connect

    Choquette, K.D.; Chow, W.W.; Hou, H.Q.; Geib, K.M.; Hammons, B.E.

    1998-01-01

    The monolithic integration of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. The authors report the first electrically injected coupled resonator vertical-cavity laser diode and demonstrate novel characteristics arising from the cavity coupling, including methods for external modulation of the laser. A coupled mode theory is used model the output modulation of the coupled resonator vertical cavity laser.

  7. Dynamics of geckos running vertically

    Microsoft Academic Search

    K. Autumn; S. T. Hsieh; D. M. Dudek; J. Chen; C. Chitaphan; R. J. Full

    2006-01-01

    Geckos with adhesive toe pads rapidly climb even smooth vertical surfaces. We challenged geckos (Hemidactylus garnotii) to climb up a smooth vertical track that contained a force platform. Geckos climbed vertically at up to 77·cm·s -1 with a stride frequency of 15·Hz using a trotting gait. During each step, whole body fore-aft, lateral and normal forces all decreased to zero

  8. Vertical landing on an asteroid

    NASA Technical Reports Server (NTRS)

    Harel, D.; Geulman, M.

    1992-01-01

    This work is concerned with the final approach phase and vertical landing on an asteroid with a power-limited, electrically propelled spacecraft. With gravitational effects taken into account, a new solution to the fuel optimal vertical landing on an asteroid was obtained. In this solution, the spacecraft commanded acceleration is explicitly expressed as a function of vehicle velocity and time to go. Based on qualitative methods of analysis, the guidance strategy and the resulting trajectories were studied. It is shown that these fuel-optimal trajectories effectively assure a vertical soft landing on the asteroid. Results of numerical simulations for the vertical landing, starting from an elliptical orbit are presented.

  9. Heat exchanger with auxiliary cooling system

    DOEpatents

    Coleman, John H. (Salem Township, Westmoreland County, PA)

    1980-01-01

    A heat exchanger with an auxiliary cooling system capable of cooling a nuclear reactor should the normal cooling mechanism become inoperable. A cooling coil is disposed around vertical heat transfer tubes that carry secondary coolant therethrough and is located in a downward flow of primary coolant that passes in heat transfer relationship with both the cooling coil and the vertical heat transfer tubes. A third coolant is pumped through the cooling coil which absorbs heat from the primary coolant which increases the downward flow of the primary coolant thereby increasing the natural circulation of the primary coolant through the nuclear reactor.

  10. Revisiting the radiative vertical velocity paradigm in the TTL

    NASA Astrophysics Data System (ADS)

    Bolot, Maximilien; Moyer, Elisabeth

    2015-04-01

    We demonstrate that uplift rates in the TTL (tropical tropopause layer) may be commonly overestimated. The mass balance of any tracer in the TTL depends on the vertical speed of large-scale uplift and the rate of convective detrainment from overshoots. Generally, uplift velocity is retrieved from the conservation of energy, assuming that the only significant factor is radiative heating.1,2 The detrainment rate is then computed from the convergence of the uplift flux, with the assumption that detrainment dominates over entrainment in the TTL. We show that this commonly calculated 'radiative vertical velocity' and the associated rate of detrainment are necessarily flawed for either of two mutually exclusive reasons. If radiative heating is the sole diabatic term in the energy budget, then significant convective entrainment must occur at TTL levels. If detrainment dominates over entrainment, then the heat budget must include the cooling rate from the export of sensible heat deficit in overshooting convection. We illustrate the calculations using tropical values of radiative heating rates and large-scale divergence fluxes from ERA-Interim reanalysis. For undilute convection, the export of heat deficit in detrained overshoots would substantially offset radiative heating, lowering the resulting assumed vertical velocity at 16 km by a factor of three. The computed detrainment rate at this altitude also increases significantly, by a factor of five. Because these changes would alter interpretation of tracer profiles, it is important to include all terms in the heat budget in tracer studies. Conversely, tracer transport properties can be used to help constrain the impact of convection on the TTL heat budget.3 [1] Folkins, I. et al., J. Geophys. Res., 111, D23304, (2006). [2] Read, W. G. et al., Atmos. Chem. Phys., 8, 6051-6067, (2008). [3] Kuang, Z. and Bretherton, C. S., J. Atmos. Sci., 61, 2919-2927, (2004)

  11. A mathematical model for the simulation of closed-loop earth-coupled heat exchangers for a water source heat pump 

    E-print Network

    De Lange, Kevin Jon

    1988-01-01

    Temperature. Pipe and Soil Temperatures. Applications. . Vertical Concentric Heat Exchanger. Horizontal Single Pipe Heat Exchanger. . . . . . Vertical U-tube Heat Exchanger Model Software. Model Parameters. Convective Surface Heat Transfer Coefficients... configurations. . . 53 14. Placement of thermocouple probes for the horizontal single pipe configuration. CHAPTER I INTRODUCTION In recent years there has been an increase in the use of heat pumps for space heating and cooling. In the late 1970's...

  12. A Simple Model of Climatological Rainfall and Vertical Motion Patterns over the Tropical Oceans

    E-print Network

    Back, Larissa E.

    A simple model is developed that predicts climatological rainfall, vertical motion, and diabatic heating profiles over the tropical oceans given the sea surface temperature (SST), using statistical relationships deduced ...

  13. Natural convection flow of a non-Newtonian fluid between two vertical flat plates

    Microsoft Academic Search

    K. R. Rajagopal; T. Y. Na

    1985-01-01

    Summary The natural convection of a homogeneous incompressible fluid of grade three is investigated between two infinite parallel vertical plates. The effect of the non-Newtonian nature of fluid on the skin friction and heat transfer are studied.

  14. Transition from film boiling to nucleate boiling in forced convection vertical flow

    E-print Network

    Iloeje, Onwuamaeze C.

    1972-01-01

    The mechanism of collapse of forced cnnvection annular vertical flow film boiling, with liquid core, is investigated using liquid nitrogen at low pressures. The report includes the effect of heat flux from the buss bar. ...

  15. Natural convection along a wavy vertical plate to non-Newtonian fluids

    Microsoft Academic Search

    E. Kim

    1997-01-01

    A numerical investigation of natural convection flow along irregular vertical surfaces in non-Newtonian fluids is reported. A wavy vertical surface is used as an example to show the heat transfer mechanism near such surfaces. The results demonstrate that with an increase of flow index, the axial velocity increases, but the velocity boundary layer becomes thinner. The difference between the velocity

  16. Localised convection cells in the presence of a vertical magnetic field

    E-print Network

    Localised convection cells in the presence of a vertical magnetic field J. H. P. Dawes Department October 27, 2005 Abstract Thermal convection in a horizontal fluid layer heated uniformly from below usually produces an array of convection cells of roughly equal amplitudes. In the presence of a vertical

  17. Prediction of the Mixture Effect On Boiling in Vertical Thermosyphon Reboilers

    Microsoft Academic Search

    JOHN R. THOME

    1989-01-01

    The present study has investigated the effect of mixtures on the nucleate boiling contribution to flow boiling inside vertical tubes at low vapor qualities, operating conditions typical of vertical thermosyphon reboilers. The mass diffusion process created by the composition difference between the vapor and liquid phases was found to impede the boiling process and substantially reduce the nucleate boiling heat

  18. Experimental characterization of flow boiling heat dissipation in a microchannel heat sink with different orientations

    Microsoft Academic Search

    H. Y. Zhang; D. Pinjala; T. N. Wong

    2005-01-01

    Experimental characterization of FC-72 flow boiling in a microchannel heat sink is presented for three different orientations: vertical upflow (VU), vertical downflow (VD) and horizontal flow with horizontal facing (HH). The heat sink consisted of 21 microchannels in parallel, with the channel dimensions of 0.2mm (W) times 2mm (H) times 15mm (L). The heat sink was attached onto a flip

  19. Condensation of steam on a vertical tube in a granulated material

    Microsoft Academic Search

    Alexander R. Bogomolov; Pavel T. Petrik; Igor V. Dvorovenko

    2007-01-01

    The heat transfer enhancement was studied during condensation of steam on a chilled vertical surface of a tube packed into\\u000a a granulated material with different contact angles of wetting. The dimensionless values of heat transfer at condensation\\u000a on a surface in filling, obtained for a vertical tube in the range of Reynolds numbers from 70 up to 400, exceed Nu*

  20. Latitude and longitude vertical disparities.

    PubMed

    Read, Jenny C A; Phillipson, Graeme P; Glennerster, Andrew

    2009-01-01

    The literature on vertical disparity is complicated by the fact that several different definitions of the term "vertical disparity" are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparities. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out. We present analytical approximations for each type of vertical disparity, valid for more general conditions than previous derivations in the literature: we do not restrict ourselves to objects near the fixation point or near the plane of regard, and we allow for non-zero torsion, cyclovergence, and vertical misalignments of the eyes. We use these expressions to derive estimates of the latitude and longitude vertical disparities expected at each point in the visual field, averaged over all natural viewing. Finally, we present analytical expressions showing how binocular eye position-gaze direction, convergence, torsion, cyclovergence, and vertical misalignment-can be derived from the vertical disparity field and its derivatives at the fovea. PMID:20055544

  1. Functions and Vertical Line Test

    NSDL National Science Digital Library

    2010-01-01

    This lesson is designed to introduce students to the vertical line test for functions as well as practice plotting points and drawing simple functions. The lesson provides links to discussions and activities related to the vertical line test and functions as well as suggested ways to integrate them into the lesson.

  2. Measuring Growth with Vertical Scales

    ERIC Educational Resources Information Center

    Briggs, Derek C.

    2013-01-01

    A vertical score scale is needed to measure growth across multiple tests in terms of absolute changes in magnitude. Since the warrant for subsequent growth interpretations depends upon the assumption that the scale has interval properties, the validation of a vertical scale would seem to require methods for distinguishing interval scales from…

  3. Numerical simulation of heating & cooling air conditioning system of solar aided ground source heat pump system with soil storage

    Microsoft Academic Search

    Fang Wang; Maoyu Zheng; Zhongjian Li

    2008-01-01

    In solar aided ground-source heat pump (SAGSHP) system with soil storage, heat collected by solar energy in three seasons was stored in soil by vertical U-type heat exchangers. Heat extracted by the ground-source heat pump combined with the heat collected by the solar collector is employed to heating. Some of the soil exchangers are used to store solar energy in

  4. A vertical microfluidic probe.

    PubMed

    Kaigala, G V; Lovchik, R D; Drechsler, U; Delamarche, E

    2011-05-01

    Performing localized chemical events on surfaces is critical for numerous applications. We earlier invented the microfluidic probe (MFP), which circumvented the need to process samples in closed microchannels by hydrodynamically confining liquids that performed chemistries on surfaces (Juncker et al. Nat. Mater. 2005, 4, 622-628). Here we present a new and versatile probe, the vertical MFP (vMFP), which operates in the scanning mode while overcoming earlier challenges that limited the practical implementation of the MFP technology. The key component of the vMFP is the head, a microfluidic device (?1 cm(2) in area) consisting of glass and Si and having microfluidic features fabricated in-plane in the Si layer. The base configuration of the head has two micrometer-size channels that inject/aspirate liquids and terminate at the apex which is ?1 mm(2). In scanning mode, the head is oriented vertically with the apex parallel to the surface with typical spacing of 1-30 ?m. Such length scales and using flow rates from nanoliters/second to microliters/second allow chemical events to be performed on surfaces with tens of picoliter quantities of reagents. Before scanning, the head is clipped on a holder for leak-free, low dead volume interface assembly, providing a simple world-to-chip interface. Surfaces are scanned by mounting the holder on a computer-controlled stage having ?0.1 ?m resolution in positioning. We present detailed steps to fabricate vMFP heads having channels with dimensions from 1 ?m × 1 ?m to 50 ?m × 50 ?m for liquid localization over areas of 10-10,000 ?m(2). Additionally, advanced design strategies are described to achieve high yield in fabrication and to support a broad range of applications. These include particulate filters, redundant aperture architectures, inclined flow-paths that service apertures, and multiple channels to enable symmetric flow confinement. We also present a method to characterize flow confinement and estimate the distance between the head and the surface by monitoring the evolution of a solution of fluorescently labeled antibody on an activated glass surface. This flow characterization reveals regimes of operation suitable for different surface topographies. We further integrate the dispensing of immersion liquid to the vMFP head for processing surfaces for extended periods of time (?60 min). The versatility of the vMFP is exemplified by patterning fluorescently labeled proteins, inactivation of cells using sodium hypochlorite, and staining living NIH fibroblasts with Cellomics. These applications are enabled by the compact design of the head, which provides easy access to the surface, simplifies alignment, and enables processing surfaces having dimensions from the micrometer to the centimeter scale and with large topographical variations. We therefore believe that ease-of-operation, reconfigurability, and conservative use of chemicals by the vMFP will lead to its widespread use by microtechnologists and the chemical and biomedical communities. PMID:21476506

  5. Heating with waste heat

    SciTech Connect

    Beabout, R.W.

    1986-09-02

    Most of the power consumed in the gaseous diffusion process is converted into heat of compression, which is removed from the process gas and rejected into the atmosphere by recirculating cooling water over cooling towers. The water being handled through the X-333 and X-330 Process Buildings can be heated to 140 to 150/sup 0/F for heating use. The Gas Centrifuge Enrichment Plant is provided with a recirculating heating water (RHW) system which uses X-330 water and wasted heat. The RHW flow is diagrammed. (DLC)

  6. Research and Development on Heat Pumps for Space Conditioning Applications: Proceedings of the DOE/ORNL Heat Pump Conference

    NASA Astrophysics Data System (ADS)

    Jacobs, V. A.; Powell, R. H., Jr.

    1985-08-01

    This conference was planned to provide information on current activities in the US Department of Energy (DOE) and Oak Ridge National Laboratory (ORNL) Building Equipment Research (BER) Program. It was primarily for the benefit of HVAC equipment manufacturers and other interested parties, including utilities, independent research and development organizations, universities, other government groups, and research funding and management organizations. The technical presentations were grouped into two principal subject areas: electric systems and thermally activated systems. Electric-system topics included field performance studies, laboratory experiments on cycling performance, analytical estimates of the benefits of variable capacity and zone control, nonazeotropic refrigerant mixtures, ground-coupled systems, and an analysis of Stirling-cycle heat pumps. In the area of thermally activated heat pumps, presentations centered on the development of absorption systems, Stirling-engine-driven systems, and a linear, free-piston IC-engine compressor. Separate abstracts have been prepared for 27 presentations for inclusion in the Energy Data Base.

  7. Heating performance of a ground source heat pump system installed in a school building

    Microsoft Academic Search

    Jaedo Song; Kwangho Lee; Youngman Jeong; Seongir Cheong; Jaekeun Lee; Yujin Hwang; Yeongho Lee; Donghyuk Lee

    2010-01-01

    The heating performance of a water-to-refrigerant type ground source heat pump system is represented in this paper under the\\u000a actual working conditions of the GSHP (ground source heat pump) system during the winter season of 2008. Ten heat pump equipments\\u000a with the capacity of 10 HP each and a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m

  8. Ground-Source Heat Pumps Applied to Commercial Buildings

    SciTech Connect

    Parker, Steven A.; Hadley, Donald L.

    2006-12-31

    Ground-source heat pumps can provide an energy-efficient, cost-effective way to heat and cool commercial facilities. While ground-source heat pumps are well established in the residential sector, their application in larger, commercial-style, facilities is lagging, in part because of a lack of experience with the technology by those in decision-making positions. Through the use of a ground-coupling system, a conventional water-source heat pump design is transformed to a unique means of utilizing thermodynamic properties of earth and groundwater for efficient operation throughout the year in most climates. In essence, the ground (or groundwater) serves as a heat source during winter operation and a heat sink for summer cooling. Many varieties in design are available, so the technology can be adapted to almost any site. Ground-source heat pump systems can be used widely in commercial-building applications and, with proper installation, offer great potential for the commercial sector, where increased efficiency and reduced heating and cooling costs are important. Ground-source heat pump systems require less refrigerant than conventional air-source heat pumps or air-conditioning systems, with the exception of direct-expansion-type ground-source heat pump systems. This chapter provides information and procedures that an energy manager can use to evaluate most ground-source heat pump applications. Ground-source heat pump operation, system types, design variations, energy savings, and other benefits are explained. Guidelines are provided for appropriate application and installation. Two case studies are presented to give the reader a sense of the actual costs and energy savings. A list of manufacturers and references for further reading are included for prospective users who have specific or highly technical questions not fully addressed in this chapter. Sample case spreadsheets are provided in Appendix A. Additional appendixes provide other information on the ground-source heat pump technology.

  9. Ground-source Heat Pumps Applied to Commercial Buildings

    SciTech Connect

    Parker, Steven A.; Hadley, Donald L.

    2009-07-14

    Ground-source heat pumps can provide an energy-efficient, cost-effective way to heat and cool commercial facilities. While ground-source heat pumps are well established in the residential sector, their application in larger, commercial-style, facilities is lagging, in part because of a lack of experience with the technology by those in decision-making positions. Through the use of a ground-coupling system, a conventional water-source heat pump design is transformed to a unique means of utilizing thermodynamic properties of earth and groundwater for efficient operation throughout the year in most climates. In essence, the ground (or groundwater) serves as a heat source during winter operation and a heat sink for summer cooling. Many varieties in design are available, so the technology can be adapted to almost any site. Ground-source heat pump systems can be used widely in commercial-building applications and, with proper installation, offer great potential for the commercial sector, where increased efficiency and reduced heating and cooling costs are important. Ground-source heat pump systems require less refrigerant than conventional air-source heat pumps or air-conditioning systems, with the exception of direct-expansion-type ground-source heat pump systems. This chapter provides information and procedures that an energy manager can use to evaluate most ground-source heat pump applications. Ground-source heat pump operation, system types, design variations, energy savings, and other benefits are explained. Guidelines are provided for appropriate application and installation. Two case studies are presented to give the reader a sense of the actual costs and energy savings. A list of manufacturers and references for further reading are included for prospective users who have specific or highly technical questions not fully addressed in this chapter. Sample case spreadsheets are provided in Appendix A. Additional appendixes provide other information on the ground-source heat pump technology.

  10. Vertically scanned laser sheet microscopy

    NASA Astrophysics Data System (ADS)

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-10-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  11. Horizontal Inequity and Vertical Redistribution

    Microsoft Academic Search

    Peter J. Lambert; Xavier Ramos

    1997-01-01

    Inequality of post-tax income among pre-tax equals is evaluated andaggregated to form a global index of horizontal inequity in the income tax.The vertical action of the tax is captured by its inequality effect on averagebetween groups of pre-tax equals. Putting the two together, horizontalinequity measures loss of vertical performance. The identification problem,which has previously been thought insuperable, is addressed by

  12. The TEXT upgrade vertical interferometer

    SciTech Connect

    Hallock, G.A.; Gartman, M.L.; Li, W.; Chiang, K.; Shin, S.; Castles, R.L.; Chatterjee, R.; Rahman, A.S. (The University of Texas at Austin, Austin, Texas 78712 (United States))

    1992-10-01

    A far-infrared interferometer has been installed on TEXT upgrade to obtain electron density profiles. The primary system views the plasma vertically through a set of large (60-cm radial{times}7.62-cm toroidal) diagnostic ports. A 1-cm channel spacing (59 channels total) and fast electronic time response is used, to provide high resolution for radial profiles and perturbation experiments. Initial operation of the vertical system was obtained late in 1991, with six operating channels.

  13. Natural convection between a vertical cylinder and a surrounding array

    SciTech Connect

    McEligot, D.M.; O`Brien, J.E.; Stoots, C.M.; Larson, T.K.; Christenson, W.A.; Mecham, D.C.; Lussie, W.G.

    1992-09-01

    The generic situation considered is natural convection between a single heated, vertical cylinder and a surrounding array of cooler vertical cylinders in a triangular pattern. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on test section diameter and air properties evaluated at cooling tube temperature, ranged from 2.9 x 10{sup 4} to 4.6 x 10{sup 5}. Results indicate that the convective heat transfer data could be approximated as Nu{sub D} (T{sub ts}/T{sub ct}){sup 0.14} = 0.156 Ra{sub D}{sup 1/3} in the apparent turbulent region for Ra{sub L} > 1.2 x 10{sup 11.}

  14. Natural convection between a vertical cylinder and a surrounding array

    SciTech Connect

    McEligot, D.M.; O'Brien, J.E.; Stoots, C.M.; Larson, T.K.; Christenson, W.A.; Mecham, D.C.; Lussie, W.G.

    1992-01-01

    The generic situation considered is natural convection between a single heated, vertical cylinder and a surrounding array of cooler vertical cylinders in a triangular pattern. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on test section diameter and air properties evaluated at cooling tube temperature, ranged from 2.9 x 10{sup 4} to 4.6 x 10{sup 5}. Results indicate that the convective heat transfer data could be approximated as Nu{sub D} (T{sub ts}/T{sub ct}){sup 0.14} = 0.156 Ra{sub D}{sup 1/3} in the apparent turbulent region for Ra{sub L} > 1.2 x 10{sup 11.}

  15. Vertical saccades in dyslexic children.

    PubMed

    Tiadi, Aimé; Seassau, Magali; Bui-Quoc, Emmanuel; Gerard, Christophe-Loïc; Bucci, Maria Pia

    2014-11-01

    Vertical saccades have never been studied in dyslexic children. We examined vertical visually guided saccades in fifty-six dyslexic children (mean age: 10.5±2.56 years old) and fifty-six age matched non dyslexic children (mean age: 10.3±1.74 years old). Binocular eye movements were recorded using an infrared video-oculography system (mobileEBT®, e(ye)BRAIN). Dyslexic children showed significantly longer latency than the non dyslexic group, also the occurrence of anticipatory and express saccades was more important in dyslexic than in non dyslexic children. The gain and the mean velocity values were significantly smaller in dyslexic than in non dyslexic children. Finally, the up-down asymmetry reported in normal population for the gain and the velocity of vertical saccades was observed in dyslexic children and interestingly, dyslexic children also reported an up-down asymmetry for the mean latency. Taken together all these findings suggested impairment in cortical areas responsible of vertical saccades performance and also at peripheral level of the extra-ocular oblique muscles; moreover, a visuo-attentionnal bias could explain the up-down asymmetry reported for the vertical saccade triggering. PMID:25151607

  16. On the Vertical Thermal Structure of Pluto's Atmosphere

    Microsoft Academic Search

    Darrell F. Strobel; Xun Zhu; Michael E. Summers; Michael H. Stevens

    1996-01-01

    A radiative–conductive model for the vertical thermal structure of Pluto's atmosphere is developed with a non-LTE treatment of solar heating in the CH43.3 ?m and 2.3 ?m bands, non-LTE radiative exchange and cooling in the CH47.6 ?m band, and LTE cooling by CO rotational line emission. The model includes the effects of opacity and vibrational energy transfer in the CH4molecule.

  17. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, P.R.; McLennan, G.A.

    1984-08-30

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  18. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, Paul R. (Western Springs, IL); McLennan, George A. (Downers Grove, IL)

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  19. Vertical motion simulator familiarization guide

    NASA Technical Reports Server (NTRS)

    Danek, George L.

    1993-01-01

    The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

  20. Simulation of embedded heat exchangers of solar aided ground source heat pump system

    Microsoft Academic Search

    Fang Wang; Mao-yu Zheng; Jun-peng Shao; Zhong-jian Li

    2008-01-01

    Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established.\\u000a In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored\\u000a in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the

  1. VERTICAL DISTRIBUTION, DIEL VERTICAL MIGRATION, AND ABUNDANCE OF SOME MESOPELAGIC FISHES IN

    E-print Network

    VERTICAL DISTRIBUTION, DIEL VERTICAL MIGRATION, AND ABUNDANCE OF SOME MESOPELAGIC FISHES: Stenobrachius leucopsarus and Diaphus theta. which performed diel vertical migrations of300 m vertical extent; andProtomyctophum thompsoni andS. nannochir. which exhibited only slight diel variation in vertical

  2. Film boiling on the inside of vertical tubes with upward flow of the fluid at low qualities

    E-print Network

    Dougall, R. S.

    1963-01-01

    Flow regimes, local heat transfer coefficients, and temperature distributions along the wall have been studied for film boiling inside a vertical tube with upward flow of a saturated liquid. The area of interest has been ...

  3. Vertical axis wind turbine development

    Microsoft Academic Search

    R. E. Walters; J. B. Fanucci; P. W. Hill; P. G. Migliore

    1979-01-01

    Theoretical and experimental research accomplished in evaluating an innovative concept for vertical axis wind turbines (VAWT) is described. The concept is that of using straight blades composed of circulation controlled airfoil sections. The theoretical analysis was developed to determine the unsteady lift and moment characteristics of multiple-blade cross-flow wind turbines. To determine the drag data needed as input to the

  4. Vertical Dynamics of Marine Risers

    Microsoft Academic Search

    W. R. Apiazu; V. N. Nguyen

    1984-01-01

    A study of the vertical dynamics of marine riser-load systems has been performed to determine the amplitude of dynamic forces and displacements caused by heave action. The analysis predicts circumstances under which slackening or compression, and subsequent failure of a riser can occur. Results show that a suitably designed heave compensator can reduce the dynamic stress amplitude to acceptable values

  5. Vertical Instability at IPNS RCS.

    SciTech Connect

    Wang, S.; Brumwell, F. R.; Dooling, J. C.; Harkay, K. C.; Kustom, R.; McMichael, G. E.; Middendorf, M. E.; Nassiri, A.; Accelerator Systems Division (APS)

    2008-01-01

    The rapid cycling synchrotron (RCS) of the intense pulsed neutron source (IPNS) at ANL accelerates > 3.0 times 10{sup 12} protons from 50 MeV to 450 MeV with 30-Hz repetition frequency. During the acceleration cycle, the rf frequency varies from 2.21 MHz to 5.14 MHz. Presently, the beam current is limited by a vertical instability. By analyzing turn-by-turn beam position monitor (BPM) data, large- amplitude mode 0 and mode 1 vertical beam centroid oscillations were observed in the later part of the acceleration cycle. The oscillations start in the tail of the bunch, build up, and remain localized in the tail half of the bunch. This vertical instability was compared with a head-tail instability that was intentionally induced in the RCS by adjusting the trim sextupoles. It appears that our vertical instability is not a classical head-tail instability [1]. More data analysis and experiments were performed to characterize the instability.

  6. Capturing vertical profiles of aerosols and black carbon over the Indian Ocean using autonomous unmanned aerial vehicles

    Microsoft Academic Search

    C. E. Corrigan; G. C. Roberts; M. V. Ramana; D. Kim; V. Ramanathan

    2008-01-01

    Measurements of the vertical distribution of aerosol properties provide essential information for generating more accurate model estimates of radiative forcing and atmospheric heating rates compared with employing remotely sensed column averaged properties. A month long campaign over the Indian Ocean during March 2006 investigated the interaction of aerosol, clouds, and radiative effects. Routine vertical profiles of aerosol and water vapor

  7. Capturing vertical profiles of aerosols and black carbon over the Indian Ocean using autonomous unmanned aerial vehicles

    Microsoft Academic Search

    C. E. Corrigan; G. C. Roberts; M. V. Ramana; D. Kim; V. Ramanathan

    2007-01-01

    Measurements of the vertical distribution of aerosol properties provide essential information for generating more accurate model estimates of radiative forcing and atmospheric heating rates compared with employing remotely sensed column averaged properties. A month long campaign over the Indian Ocean during March 2006 investigated the interaction of aerosol, clouds, and radiative effects. Routine vertical profiles of aerosol and water vapor

  8. Graphene vertical hot-electron terahertz detectors

    SciTech Connect

    Ryzhii, V., E-mail: v-ryzhii@riec.tohoku.ac.jp [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University and Institute of Ultra High Frequency Semiconductor Electronics, Russian Academy of Sciences, Moscow 111005 (Russian Federation); Satou, A.; Otsuji, T. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Mitin, V. [Department of Electrical Engineering, University at Buffalo, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Departments of Electrical, Electronics, and Systems Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2014-09-21

    We propose and analyze the concept of the vertical hot-electron terahertz (THz) graphene-layer detectors (GLDs) based on the double-GL and multiple-GL structures with the barrier layers made of materials with a moderate conduction band off-set (such as tungsten disulfide and related materials). The operation of these detectors is enabled by the thermionic emissions from the GLs enhanced by the electrons heated by incoming THz radiation. Hence, these detectors are the hot-electron bolometric detectors. The electron heating is primarily associated with the intraband absorption (the Drude absorption). In the frame of the developed model, we calculate the responsivity and detectivity as functions of the photon energy, GL doping, and the applied voltage for the GLDs with different number of GLs. The detectors based on the cascade multiple-GL structures can exhibit a substantial photoelectric gain resulting in the elevated responsivity and detectivity. The advantages of the THz detectors under consideration are associated with their high sensitivity to the normal incident radiation and efficient operation at room temperature at the low end of the THz frequency range. Such GLDs with a metal grating, supporting the excitation of plasma oscillations in the GL-structures by the incident THz radiation, can exhibit a strong resonant response at the frequencies of several THz (in the range, where the operation of the conventional detectors based on A{sub 3}B{sub 5} materials, in particular, THz quantum-well detectors, is hindered due to a strong optical phonon radiation absorption in such materials). We also evaluate the characteristics of GLDs in the mid- and far-infrared ranges where the electron heating is due to the interband absorption in GLs.

  9. An Experimental Study of Upward and Downward Flow of Supercritical Carbon Dioxide in a Straight Pipe Heat Exchanger with Constant Wall Heat Flux

    E-print Network

    Umrigar, Eric Dara

    2014-05-01

    An experimental analysis was conducted on a single circular tube heat exchanger using supercritical carbon dioxide as the working fluid. The heat exchanger was operated in two different orientations: vertically upward and downward. The experimental...

  10. AIAA Journal of Thermophysics and Heat Transfer Vol. 13(1), pp. 126-133, 1999

    E-print Network

    Zhao, Tianshou

    Transfer in a Capillary Structure Heated by a Grooved Block Q. Liao* and T. S. Zhao The Hong Kong1 AIAA Journal of Thermophysics and Heat Transfer Vol. 13(1), pp. 126-133, 1999 Evaporative Heat of capillary-driven heat and mass transfer in a vertical rectangular capillary porous structure heated from

  11. Calculation of turbulent mixed convection in a vertical tube using a low-Reynolds-number k-epsilon turbulence model

    Microsoft Academic Search

    M. A. Cotton; J. D. Jackson

    1987-01-01

    A low-Reynolds-number k-epsilon turbulent model developed by Launder and Sharma (1974) was used to examine mixed convection heat transfer in ascending and descending flows in a vertical heated tube. The numerical solutions of the governing equations were obtained using a computer code CONVERT (for convection in vertical tubes) developed for the present studies. Discretization was performed according to a finite

  12. Tropical Cyclone Intensity in Vertical Wind Shear.

    NASA Astrophysics Data System (ADS)

    Wong, Martin L. M.; Chan, Johnny C. L.

    2004-08-01

    The structure and intensity changes of tropical cyclones (TCs) in environmental vertical wind shear (VWS) are investigated in this study using the fifth-generation Pennsylvania State University National Center for Atmospheric Research (PSU NCAR) Mesoscale Model (MM5). Triply nested domains of 36-, 12-, and 4-km resolution are used with fully explicit moisture physics in the 4-km domain. Idealized environments with easterly shears of 2, 4, 6, 8, and 10 m s-1 between 800 and 200 hPa are applied on an f plane. Under small values of VWS (2 and 4 m s-1), the TC intensities are similar to that of the control (CTRL; i.e., no VWS) after initial adjustments. The TCs under 6 and 8 m s-1 of VWS are not as intense, although they do not weaken during the simulation. On the other hand, the TC in 10 m s-1 of VWS weakened significantly.Given the same VWS, the TC intensity is also found to be sensitive to TC size. Experiments with TCs with a smaller radius of 15 m s-1 wind reveal that while the TC in 2 m s-1 of VWS remains as intense as the CTRL, the TC in the 4 m s-1 VWS case weakened significantly to a minimal hurricane by the end of the simulation. A VWS of 6 m s-1 is strong enough to cause dissipation of the TC in 72 h. These results indicate that the size of a TC has to be taken into account in determining the intensity change of a TC in VWS.In the 10 m s-1 VWS case, the average temperature over the lower half of the troposphere within 50 km from the TC surface center is higher than that of the CTRL throughout the simulation. Such a warming, though of a small magnitude, is also observed for a brief period in the upper half of the troposphere before the rapid weakening of the TC and is related to the asymmetry of temperature required for a tilt of the vortex axis. The evolution of the vortex tilt is found to be similar to the dry simulations in previous studies, with the midlevel center (? = 0.525) located mainly in the southeast quadrant of the surface center. A tendency for the midlevel center to rotate about the surface center is also observed. These results support the idea that the resistance to vertical tilt by the mutual rotation between the low-level and midlevel centers is also valid in the moist simulations.It is hypothesized that the secondary circulation and the associated diabatic heating reduce the vertical tilt and the weakening. Condensation heating offsets the anomalous cooling effect due to the anomalous rising motion ahead of the vortex tilt. For small VWS, the vertical motion asymmetry is not strong enough to destroy the complete secondary circulation and the eyewall. As a result, a large temperature asymmetry and the associated vortex tilt cannot develop. Furthermore, there is no entrainment of cool/dry air in the upper troposphere. Therefore, TCs under small shears can be as intense as the CTRL.Large-scale asymmetries in the form of anticyclones found in previous studies are also observed. These asymmetries are apparently related to the change of shears near the TCs. While the shears at outer radii stay roughly constant with time, the shears near the TC centers can have large temporal fluctuations both in magnitude and orientation. This result suggests that the location at which the VWS is estimated in observational studies could be important in determining the relationship between VWS and TC intensity change.


  13. Electric characteristics of germanium Vertical Multijunction (VMJ) photovoltaic cells under high intensity illumination

    SciTech Connect

    Unishkov, V.A. [Quantum Group, Inc., 11211 Sorrento Valley Road, San Diego, California 92121 (United States)

    1997-03-01

    This paper presents the results of the performance evaluation of Vertical Multijunction (VMJ) germanium (Ge) photovoltaic (PV) cells. Vertical Multijunction Germanium Photovoltaic cells offer several advantages for Thermophotovoltaic (TPV) applications such as high intensity light conversion, low series resistance, more efficient coupling to lower temperature sources, high output voltage, simplified heat rejection system as well as potentially simple fabrication technology and low cost photovoltaic converter device. {copyright} {ital 1997 American Institute of Physics.}

  14. Numerical simulation of variable polarity vertical-up plasma arc welding process

    Microsoft Academic Search

    H. X. Wang; Y. H. Wei; C. L. Yang

    2007-01-01

    Three-dimensional transient governing equations were developed based on conservation laws of energy, momentum and mass. These equations described physical phenomena of convection in weld pool and heat transfer in workpiece during variable polarity vertical-up plasma arc welding process. Boundary conditions for the developed governing equations were given. Welding energy input for variable polarity vertical-up plasma arc welding process was quantitatively

  15. Solar and ground source heat-pump system

    Microsoft Academic Search

    Yuehong Bi; Tingwei Guo; Liang Zhang; Lingen Chen

    2004-01-01

    Theoretical and experimental studies were performed for a solar-ground source heat-pump (SGSHP) system with a vertical double-spiral coil (VDSC) ground heat-exchanger (GHX). The heating mode of the SGSHP system is alternated between a solar energy-source heat-pump (SSHP) and a ground-source heat-pump (GSHP) using a low-grade energy utilization system built by the authors. The measured performances were for the SSHP, GSHP

  16. Heat Pipes

    ERIC Educational Resources Information Center

    Lewis, J.

    1975-01-01

    Describes the construction, function, and applications of heat pipes. Suggests using the heat pipe to teach principles related to heat transfer and gives sources for obtaining instructional kits for this purpose. (GS)

  17. Coronal heating

    NASA Technical Reports Server (NTRS)

    Wentzel, D. G.

    1981-01-01

    Theoretical arguments for coronal heating that take into account coronal structure are reviewed. Heating by the dissipation of electrical currents and heating by dissipation of waves are discussed. Loop structures in the solar corona are described.

  18. Vertically Integrated Circuits at Fermilab

    SciTech Connect

    Deptuch, Grzegorz; Demarteau, Marcel; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab

    2009-01-01

    The exploration of the vertically integrated circuits, also commonly known as 3D-IC technology, for applications in radiation detection started at Fermilab in 2006. This paper examines the opportunities that vertical integration offers by looking at various 3D designs that have been completed by Fermilab. The emphasis is on opportunities that are presented by through silicon vias (TSV), wafer and circuit thinning and finally fusion bonding techniques to replace conventional bump bonding. Early work by Fermilab has led to an international consortium for the development of 3D-IC circuits for High Energy Physics. The consortium has submitted over 25 different designs for the Fermilab organized MPW run organized for the first time.

  19. Vertically Integrated Circuits at Fermilab

    SciTech Connect

    Deptuch, Grzegorz; Demarteau, Marcel; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab

    2010-01-01

    The exploration of vertically integrated circuits, also commonly known as 3D-IC technology, for applications in radiation detection started at Fermilab in 2006. This paper examines the opportunities that vertical integration offers by looking at various 3D designs that have been completed by Fermilab. The emphasis is on opportunities that are presented by through silicon vias (TSV), wafer and circuit thinning, and finally fusion bonding techniques to replace conventional bump bonding. Early work by Fermilab has led to an international consortium for the development of 3D-IC circuits for High Energy Physics. For the first time, Fermilab has organized a 3D MPW run, to which more than 25 different designs have been submitted by the consortium.

  20. Carbothermic reduction with parallel heat sources

    DOEpatents

    Troup, Robert L. (Murrysville, PA); Stevenson, David T. (Washington Township, Washington County, PA)

    1984-12-04

    Disclosed are apparatus and method of carbothermic direct reduction for producing an aluminum alloy from a raw material mix including aluminum oxide, silicon oxide, and carbon wherein parallel heat sources are provided by a combustion heat source and by an electrical heat source at essentially the same position in the reactor, e.g., such as at the same horizontal level in the path of a gravity-fed moving bed in a vertical reactor. The present invention includes providing at least 79% of the heat energy required in the process by the electrical heat source.

  1. NASA-Ames vertical gun

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.

    1984-01-01

    A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

  2. Towards a New Vertical Datum

    NASA Astrophysics Data System (ADS)

    Roman, D. R.; Li, X.; Holmes, S. A.; Childers, V. A.; Wang, Y.

    2012-12-01

    The National Geodetic Survey (NGS) is responsible for maintaining and improving the National Spatial Reference System. This paper particularly focuses on developments leading to a new vertical datum to replace the existing North American Vertical Datum of 1988 (NAVD 88). This new model will be developed from a combination of satellite, airborne, and terrestrial gravity data to define a gravimetric geoid height model. In particular, the aerogravity data collected as a part o the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project are intended to help achieve the goal of a cm-level accurate geoid model to serve as the new vertical datum. The different data sources have been melded into a single gravity field model consistent across the entire spectrum to about 2 km resolution. A previous comparison developed a localized model over just the southern Texas region, where the Geoid Slope Validation Study for 2011 (GSVS 11) demonstrated that it was possible to achieve the desired accuracy. This new model was developed using methodology consistent at regional to national scales following techniques used to make USGG2009 and USGG2012, but now incorporating aerogravity. This new model proves out the basic concepts behind GRAV-D in that the aeorgravity bridge the spectral gap between satellite and terrestrial data and provide the requisite improvements to the derived gravimetric geoid height model - all without artificially targeting a solution to a specific test area. Additional comparisons were made to tidal bench mark data observed by GPS in combination with ocean topography models to validate the behavior of the model in the coastal regions.

  3. 16 Heat Transfer and Air Flow in a Domestic Refrigerator

    E-print Network

    Paris-Sud XI, Université de

    445 16 Heat Transfer and Air Flow in a Domestic Refrigerator Onrawee Laguerre UMR Génie Industriel........................................................................447 16.2.2 Heat Transfer and Airflow Near a Vertical Plate..................................................448 16.2.3 Heat Transfer and Airflow in Empty Closed Cavity

  4. Direct contact heat exchangers in geothermal power production

    Microsoft Academic Search

    I. Sheinbaum

    1975-01-01

    The direct contact cycle can be advantageously utilized in the production of power from liquid dominated geothermal resources. The heat from the geothermal resource is transferred to a selected working fluid by direct countercurrent contact in a vertical perforated trayed tower. The direct contactor is divided into three heat transfer zones where heat is extracted from the hot water by

  5. Thermosyphon boiling in vertical channels

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, A.; Schweitzer, H.

    The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of heat transfer from the channel walls. Experimental results for wall temperature as a function of axial location, heat flux, and plate spacing are presented. The finding that the wall superheat at constant imposed heat flux decreases as the channel is narrowed is explained with the aid of a boiling thermosiphon analysis which yields the mass flux through the channel.

  6. Radiogenic heat production, thermal regime and evolution of continental crust Jean-Claude Mareschal a,

    E-print Network

    Long, Bernard

    velocities below the Moho. Notably, heat flow studies have delin- eated the vertical distribution of heat within a single geological province. For a given crustal thickness, the Moho temperature varies within

  7. A visualization comparison of convective flow boiling heat transfer augmentation devices

    E-print Network

    Lundy, Brian Franklin

    1998-01-01

    The qualitative effects of inset-table heat transfer phics. augmentation devices on vertical in-tube convective flow boiling flow regimes, transition mechanisms, and heat transfer are presented in this study. Three twisted tapes with twist ratios...

  8. A visualization comparison of convective flow boiling heat transfer augmentation devices 

    E-print Network

    Lundy, Brian Franklin

    1998-01-01

    The qualitative effects of inset-table heat transfer phics. augmentation devices on vertical in-tube convective flow boiling flow regimes, transition mechanisms, and heat transfer are presented in this study. Three twisted tapes with twist ratios...

  9. Exergoeconomic analysis of a solar assisted ground-source heat pump greenhouse heating system

    Microsoft Academic Search

    Onder Ozgener; Arif Hepbasli

    2005-01-01

    EXCEM analysis may prove useful to investigators in engineering and other disciplines due to the methodology are being based on the quantities exergy, cost, energy and mass. The main objective of the present study is to investigate between capital costs and thermodynamic losses for devices in solar assisted ground-source heat pump greenhouse heating system (SAGSHPGHS) with a 50 m vertical

  10. Heat pumps

    Microsoft Academic Search

    Heap

    1983-01-01

    An updated version of the 1979 first edition of this work for designers, specifiers, suppliers, installers, and users of heat pumps. Its aim is to assist in the reassessment of energy costs and cost relativities of the various applications of heat pumps. It presents the development of the heat pump markets, research into advanced heat pump systems, and development of

  11. Vertical variation of vertical hydraulic conductivity in channel sediments

    NASA Astrophysics Data System (ADS)

    Chen, X.; Song, J.; Cheng, C.; Wang, D.; Lackey, S.; Burbach, M.

    2007-12-01

    Vertical hydraulic conductivity (Kv) of streambed is of great importance in the analysis of stream-aquifer interactions. We used two methods to estimate the Kv in three rivers of Nebraska. The first method was in-situ permeameter test in river channels. We investigated streambed vertical hydraulic conductivity (Kv) in two depths, one incumbent to the other, immediately beneath the channel surface. Our results demonstrated that streambed Kv in the upper sediment layer was much higher than that in the sediment just beneath the upper layer at each test location. We speculate that hyporheic processes can result in a larger streambed Kv in the upper part of channel sediments. Specifically, water exchange through upwelling and downwelling zones can lead to bigger pore spaces and a more unconsolidated structure of sediments in the upper layer. The upward movement of gas produced by redox processes can loosen sediments and further enlarge pore spaces in the upper layers. Bio- activity in the upper part of the streambed can also expand pore space and thus increase hydraulic conductivity. In-situ permeameter tests penetrated the sediment to depth as much as 90 cm. We then used Geoprobe direct- push technique to generate electrical conductivity log and collect sequences of sediment cores from larger depths. Permeameter tests were conducted on these cores to determine Kv. Our results suggest that Kv values have a decrease tendency with the depth for sediments in these rivers.

  12. ATLAS LTCS Vertically Challenged System Lessons Learned

    NASA Technical Reports Server (NTRS)

    Patel, Deepak; Garrison, Matt; Ku, Jentung

    2014-01-01

    Re-planning of LTCS TVAC testing and supporting RTA (Receiver Telescope Assembly) Test Plan and Procedure document preparation. The Laser Thermal Control System (LTCS) is designed to maintain the lasers onboard Advanced Topographic Laser Altimeter System (ATLAS) at their operational temperatures. In order to verify the functionality of the LTCS, a thermal balance test of the thermal hardware was performed. During the first cold start of the LTCS, the Loop Heat Pipe (LHP) was unable to control the laser mass simulators temperature. The control heaters were fully on and the loop temperature remained well below the desired setpoint. Thermal analysis of the loop did not show these results. This unpredicted behavior of the LTCS was brought up to a panel of LHP experts. Based on the testing and a review of all the data, there were multiple diagnostic performed in order to narrow down the cause. The prevailing theory is that gravity is causing oscillating flow within the loop, which artificially increased the control power needs. This resulted in a replan of the LTCS test flow and the addition of a GSE heater to allow vertical operation.

  13. Experimental study of two-phase water flow in vertical thin rectangular channels

    NASA Astrophysics Data System (ADS)

    Wright, Christopher T.; O'Brien, James E.; Anderson, Elgin A.

    2001-11-01

    An experimental heat transfer study of two-phase water flow in vertical thin rectangular channels with side vents is conducted. A multiple, heated channel configuration with up- and down-flow conditions is investigated. Parallel heated and unheated flow channels test the effects of cross flow on the onset of nucleate boiling (ONB) and critical heat flux (CHF). The test apparatus provides pressure and substrate temperature data and visual data of the boiling regimes and side-vent flow patterns. The objectives are to determine the two-phase, heat and mass transfer characteristics between adjacent channels as permitted by side-vent cross flow. These data will help develop ONB and CHF correlations for flow geometries typical of plate-type nuclear reactors and heat exchangers. Fundamentally, the data shows how the geometry, flow conditions, and channel configurations affect the heat transfer characteristics of interior channel flows, essential in understanding the ONB and CHF phenomena.

  14. Vertical jumping and signaled avoidance

    PubMed Central

    Cándido, Antonio; Maldonado, Antonio; Vila, Jaime

    1988-01-01

    This paper reports an experiment intended to demonstrate that the vertical jumping response can be learned using a signaled-avoidance technique. A photoelectric cell system was used to record the response. Twenty female rats, divided equally into two groups, were exposed to intertrial intervals of either 15 or 40 s. Subjects had to achieve three successive criteria of acquisition: 3, 5, and 10 consecutive avoidance responses. Results showed that both groups learned the avoidance response, requiring increasingly larger numbers of trials as the acquisition criteria increased. No significant effect of intertrial interval was observed. PMID:16812559

  15. Neighbourly polytopes with few vertices

    SciTech Connect

    Devyatov, Rostislav A [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

    2011-10-31

    A family of neighbourly polytopes in R{sup 2d} with N=2d+4 vertices is constructed. All polytopes in the family have a planar Gale diagram of a special type, namely, with exactly d+3 black points in convex position. These Gale diagrams are parametrized by 3-trees (trees with a certain additional structure). For all polytopes in the family, the number of faces of dimension m containing a given vertex A depends only on d and m. Bibliography: 7 titles.

  16. Vertical dynamics of marine risers

    SciTech Connect

    Apiazu, W.R.; Nguyen, V.N.

    1984-05-01

    A study of the vertical dynamics of marine riser-load systems has been performed to determine the amplitude of dynamic forces and displacements caused by heave action. The analysis predicts circumstances under which slackening or compression, and subsequent failure of a riser can occur. Results show that a suitably designed heave compensator can reduce the dynamic stress amplitude to acceptable values under all operating modes including hangoff, by increasing compliance at the riser vessel interface. Finally, recommendations for the design of heave compensation equipment intended to limit the dynamic force amplitude on riser-load systems hanging in deeper waters and harsher environments are presented.

  17. Vertical-Bloch-Line Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.

    1993-01-01

    Vertical-Bloch-line memory is developmental very-large-scale integrated-circuit block-access magnetic memory. Stores data in form of localized pairs of twists (VBL pairs) in magnetic field at edge of ferromagnetic domain in each stripe. Presence or absence of VBL pair at bit position denotes one or zero, respectively. Offers advantages of resistance to ionizing radiation, potential areal storage density approximately less than 1 Gb/cm squared, data rates approximately less than 1 Gb/s, and average access times of order of milliseconds. Furthermore, mass, volume, and demand for power less than other magnetic and electronic memories.

  18. State-of-the-art survey of existing knowledge for the design of ground-source heat pumps

    NASA Astrophysics Data System (ADS)

    Ball, D. A.; Fischer, R. D.; Talbert, S. G.; Hodgett, D.; Auer, F.

    1983-11-01

    The gathering of design and performance information on historical and current ground coil heat pump systems, to assess the adequacy of available design methods, and to define near future R and D needs to promote the use of this technology is reported. The project was separated into two parts: (1) a review of the North American technology conducted by Battelle-Columbus; and (2) a review of European technology conducted by Battelle-Frankfurt. Descriptions of basic ground coil design configurations, operating experience, design methodologies, and reviews of costs of existing installations are included. It is found that further design method development efforts are necessary to provide installers and manufacturers with pertinent design information in order to stimulate further implementation of ground coupled heat pumps in the United States. A research effort is needed to develop parametric data on the design and performance of a ground coil during cooling using heat and moisture models.

  19. Numerical simulation of flow boiling for organic fluid with high saturation temperature in vertical porous coated tube

    Microsoft Academic Search

    Dong Yang; Jie Pan; Yanhua Wu; Tingkuan Chen; Chenn Q. Zhou

    2011-01-01

    A semi-analytical model is developed for the prediction of flow boiling heat transfer inside vertical porous coated tubes. The model assumes that the forced convection and nucleate boiling coexist together in the annular flow regime. Conservations of mass, momentum, and energy are used to solve for the liquid film thickness and temperature. The heat flux due to nucleate boiling consists

  20. Turbulent free convection in a vertical converging channel

    NASA Astrophysics Data System (ADS)

    Badr, H. M.; Habib, M. A.; Ben-Mansour, R.; Said, S. A. M.; Ayinde, T. F.; Anwar, S.

    2011-11-01

    This paper presents the results of experimental and numerical investigations of the problem of turbulent natural convection in a converging-plate vertical channel. The channel has two isothermally heated inclined walls and two adiabatic vertical side walls. The parameters involved in this study are the channel geometry represented by the channel width at exit, the inclination of the heated walls and the temperature difference between the heated walls and the ambient. The investigation covered modified Rayleigh numbers up to 108 in the computational study and up to 9.3 × 106 in the experimental work. The experimental measurements focused on the velocity field and were carried out using a PIV system and included measurements of the mean velocity profiles as well as the root-mean-square velocity and shear stress profiles. The experiments were conducted for an inclination angle of 30°, a gap width of 10 mm and two temperature differences (?T=25.4°C and 49.8°C). The velocity profiles in the lower part of the channel indicated the presence of two distinct layers. The first layer is adjacent to the heated plate and driven by buoyancy forces while the second layer extends from the point of maximum velocity to the channel center plane and driven mainly by shear forces. The velocity profile at the upper portion of the channel has shown the merging of the two boundary layers growing over the two heated walls. The measured values of the Reynolds shear stress and root mean square of the horizontal and vertical velocity fluctuation components have reached their maximum near the wall while having smaller values in the core region. The computational results have shown that the average Nusselt number increases approximately linearly with the increase of the modified Rayleigh number when plotted on log-log scale. The variation of the local Nusselt number indicated infinite values at the channel inlet (leading edge effect) and high values at the channel exit (trailing edge effect). For a fixed value of the top channel opening, the increase of the inclination angle tended to reduce flow velocity at the inlet section while changing the flow structure near the heated plates in such a way to create boundary-layer type flow. The maximum value of the average Nusselt number occurs when ? = 0 and decreases with the increase of the inclination angle. On the other hand, the increase of the channel width at exit for the same inclination angle caused a monotonic increase in the flow velocity at the channel inlet.

  1. Heating Structures Derived from Satellite

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Adler, R.; Haddad, Z.; Hou, A.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C.; Lang, S.; Meneghini, R.; Olson, W.

    2004-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan space project, was launched in November 1997. It provides an accurate measurement of rainfall over the global tropics which can be used to estimate the four-dimensional structure of latent heating over the global tropics. The distributions of rainfall and inferred heating can be used to advance our understanding of the global energy and water cycle. This paper describes several different algorithms for estimating latent heating using TRMM observations. The strengths and weaknesses of each algorithm as well as the heating products are also discussed. The validation of heating products will be exhibited. Finally, the application of this heating information to global circulation and climate models is presented.

  2. Entirely passive heat pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, Daniel R. (Santa Fe, NM)

    1982-01-01

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  3. Evaporative Heat Transfer in a Capillary Structure Heated by a Grooved Block

    Microsoft Academic Search

    Q. Liao; T. S. Zhao

    1999-01-01

    Experimental results of capillary-driven heat and mass transfer in a vertical rectangular capillary porous structure heated from a grooved block placed on the top are reported in this paper. The formation of the liquid-vapor menisci in the vicinity of the downward-facing heated surface provided the capillary-force for the upflow of water in the porous structure. The temperature distributions in both

  4. Evaporation and condensation of steam-water in a vertical tube

    Microsoft Academic Search

    G. Sun; G. F. Hewitt

    2001-01-01

    Heat Transfer data have been obtained for water from single-phase flow to two-phase annular flow at 0.07–0.09 MPa in a 9.5 mm vertical bore tube under conditions of evaporation and condensation in the same test section. The main aim of the experiments was to elucidate the mechanism of heat transfer in annular flow by distinguishing between the conventional explanation of

  5. Effect of surfactant concentration on saturated flow boiling in vertical narrow annular channels

    Microsoft Academic Search

    G. Hetsroni; M. Gurevich; A. Mosyak; R. Rozenblit

    2007-01-01

    Saturated flow boiling of environmentally acceptable nonionic surfactant solutions of Alkyl (8–16) was compared to that of pure water. The concentration of surfactant solutions was in the range of 100–1000ppm. The liquid flowed in an annular gap of 2.5 and 4.4mm between two vertical tubes. The heat was transferred from the inner heated tube to two-phase flow in the range

  6. Analysis of tropical radiative heating profiles: A comparison of models and observations

    Microsoft Academic Search

    Sally A. McFarlane; James H. Mather; Thomas P. Ackerman

    2007-01-01

    The vertical distribution of radiative heating in the atmosphere is an important driver of atmospheric circulation. Evaluation of model simulations of the Earth's radiation budget typically focus only on performance at the top of the atmosphere or at the surface. In this study, we compare the vertical distribution of cloud properties and radiative heating rates calculated from observations at the

  7. Analysis of tropical radiative heating profiles: A comparison of models and observations

    Microsoft Academic Search

    Sally A. McFarlane; James H. Mather; Thomas P. Ackerman

    2007-01-01

    Vertical distribution of radiative heating in the atmosphere is an important driver of atmospheric circulation, especially in the tropics. Evaluation of model simulations of the Earth's radiation balance typically focus on performance at the top of the atmosphere or at the surface. This study compares the vertical distribution of clouds and radiative heating rates calculated from observations at the Department

  8. Numerical study of natural convection in partially heated rectangular enclosures filled with nanofluids

    Microsoft Academic Search

    Hakan F. Oztop; Eiyad Abu-Nada

    2008-01-01

    Heat transfer and fluid flow due to buoyancy forces in a partially heated enclosure using nanofluids is carried out using different types of nanoparticles. The flush mounted heater is located to the left vertical wall with a finite length. The temperature of the right vertical wall is lower than that of heater while other walls are insulated. The finite volume

  9. Thermosyphon boiling in vertical channels

    Microsoft Academic Search

    A. Bar-Cohen; H. Schweitzer

    1983-01-01

    The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of

  10. On the Vertical Structuring of Gigantic Jets

    NASA Astrophysics Data System (ADS)

    Da Silva, C.; Pasko, V. P.

    2013-12-01

    Gigantic Jets (GJs) are large-scale electrical discharges between the thundercloud tops and the lower ionosphere. It is estimated that an individual GJ can contribute as much as cloud-to-ground lightning in discharging a thunderstorm system, transferring hundreds of coulombs from thundercloud to the ionosphere [Cummer et al., Nat. Geosci., 2, 617-620, 2009]. GJs are initiated deep inside the thundercloud as intracloud lightning discharges. Owing to a charge imbalance, meaning the upper charge center is depleted with respect to the midlevel charge center, the upward-directed lightning leaders manage to escape through the thundercloud top to form GJs [Krehbiel et al., Nat. Geosci., 1, 233-237, 2008]. As a GJ leader crosses the stratosphere its streamer zone becomes longer and longer, due to the dynamics of streamer growth in a medium with exponentially-decreasing air density, such as in the Earth's atmosphere [Raizer et al., GRL, 33, L23801, 2006]. The speed at which a leader propagates is limited by the air heating of every newly formed leader section, rate of which is slower at upper altitudes in the Earth's atmosphere [da Silva and Pasko, GRL, 39, L13805, 2012]. Despite the expected deceleration of an upward-directed leader, GJs are observed to accelerate as they approach the ionosphere. To address this issue, we propose a simple time-dynamic model for GJ propagation that simulates the upward propagation of a leader discharge accounting for the effects of the expansion of its streamer zone. We propose that the GJ acceleration is a consequence of its vertical structuring and, therefore, can be used to trace the transition altitude between the leader and streamer zone sections of GJs [da Silva and Pasko, GRL, 40, 12, 3315-3319, 2013]. Leaders and streamers are very different electrical discharges in terms of the degree of ionization, temperature, and composition of the plasma inside their channels. A correct description of the vertical structuring of GJs is of fundamental importance for evaluation of their effects in the stratosphere and mesosphere.

  11. A Study of Heat Transfer for Two Layered Composite Inclined Plate Crotch Absorbers

    E-print Network

    Kemner, Ken

    1S-143 M. Choi Nov., 1989 A Study of Heat Transfer for Two Layered Composite Inclined Plate Crotch used in CESR. They analyzed the heat transfer problem numerically for the case of a vertically located to the inclined photon beam penetration heating. An analytical solution for heat transfer is obtained for a full

  12. Gas-liquid flow and heat transfer

    SciTech Connect

    Hewitt, G.F.; Whalley, P.B.

    1984-01-01

    This book covers almost the total field of gas-liquid flow and heat transfer, reviewing and collating recent information. Contents (partial): Introduction. Regimes of flow. General analytical and empirical relationships in two phase flow. Interfacial waves. Creation and behaviour of entrained droplets. Bubble flow. Plug flow. Hydrodynamics of co-current vertical annular flow. Hydrodynamics and limits of counter-current flows. Stratified wavy and slug flow in horizontal tubes. Hydrodynamics of annular flows in nonvertical channels and complex. Introduction to two phase heat transfer. Heat transfer in annular flow. Burnout. Post burnout heat transfer. Rewetting and reflooding. Experimental techniques.

  13. Numerical Simulation of Liquid Nitrogen Chilldown of a Vertical Tube

    NASA Technical Reports Server (NTRS)

    Darr, Samuel; Hu, Hong; Schaeffer, Reid; Chung, Jacob; Hartwig, Jason; Majumdar, Alok

    2015-01-01

    This paper presents the results of a one-dimensional numerical simulation of the transient chilldown of a vertical stainless steel tube with liquid nitrogen. The direction of flow is downward (with gravity) through the tube. Heat transfer correlations for film, transition, and nucleate boiling, as well as critical heat flux, rewetting temperature, and the temperature at the onset of nucleate boiling were used to model the convection to the tube wall. Chilldown curves from the simulations were compared with data from 55 recent liquid nitrogen chilldown experiments. With these new correlations the simulation is able to predict the time to rewetting temperature and time to onset of nucleate boiling to within 25% for mass fluxes ranging from 61.2 to 1150 kg/(sq m s), inlet pressures from 175 to 817 kPa, and subcooled inlet temperatures from 0 to 14 K below the saturation temperature.

  14. Crystallization of aluminum alloys in the presence of vertical electromagnetic force fields

    Microsoft Academic Search

    Charles Vivès

    1997-01-01

    The influence of vertical and steady electromagnetic force fields applied during the solidification of representative aluminum alloys was investigated. The experiments were performed both in the absence and in the presence of electromagnetic body force fields, oriented either upward or downward, and for various degrees of heat extraction rate. Several physical mechanisms of magnetohydrodynamic origin, acting on the macro- and

  15. Vertical Structure of Tropical Cyclones with Concentric Eyewalls as Seen by the TRMM Precipitation Radar

    E-print Network

    Houze Jr., Robert A.

    Measurement Mission satellite's Precipitation Radar are analyzed to determine the typical vertical structure which they evolve. Their lower-tropospheric portions are more intense and more uniform than rainbands and has significant impacts on the vorticity, wind, and heating distribution within the storm

  16. [Architectural analysis of vertical dimension].

    PubMed

    Danguy, M; Danguy, C

    2003-09-01

    Laude and the Lille orthodontic department describe the trigeminal nerve as the main architect of the face. Using the points where it emerges into the cranium, the authors propose an analysis, which they base on four concepts: --the stability of the pterygoid base, --the interaction between two activities, prehensile and masticatory, of the oral cavity, --the cranio-mandibular entity, --the importance of the paired fifth cranial nerve. This study deals with vertical dimension of both alveolar and basal bone, as well as global, ramal, and maxillary growth directions, which they conceptualize as three parallel, convergent, or divergent lines. This analysis can be carried out quickly and easily because it requires only four simple measurements. PMID:15301369

  17. Plasma vertical stabilisation in ITER

    NASA Astrophysics Data System (ADS)

    Gribov, Y.; Kavin, A.; Lukash, V.; Khayrutdinov, R.; Huijsmans, G. T. A.; Loarte, A.; Snipes, J. A.; Zabeo, L.

    2015-07-01

    This paper describes the progress in analysis of the ITER plasma vertical stabilisation (VS) system since its design review in 2007–2008. Two indices characterising plasma VS were studied. These are (1) the maximum value of plasma vertical displacement due to free drift that can be stopped by the VS system and (2) the maximum root mean square value of low frequency noise in the dZ/dt measurement signal used in the VS feedback loop. The first VS index was calculated using the PET code for 15 MA plasmas with the nominal position and shape. The second VS index was studied with the DINA code in the most demanding simulations for plasma magnetic control of 15 MA scenarios with the fastest plasma current ramp-up and early X-point formation, the fastest plasma current ramp-down in a divertor configuration, and an H to L mode transition at the current flattop. The studies performed demonstrate that the VS in-vessel coils, adopted recently in the baseline design, significantly increase the range of plasma controllability in comparison with the stabilising systems VS1 and VS2, providing operating margins sufficient to achieve ITER's goals specified in the project requirements. Additionally two sets of the DINA code simulations were performed with the goal of assessment of the capability of the PF system with the VS in-vessel coils: (i) to control the position of runaway electrons generated during disruptions in 15 MA scenarios and (ii) to trigger ELMs in H-mode plasmas of 7.5 MA/2.65 T scenarios planned for the early phase of ITER operation. It was also shown that ferromagnetic structures of the vacuum vessel (ferromagnetic inserts) and test blanket modules insignificantly affect the plasma VS.

  18. Performance analysis of a solar-assisted ground-source heat pump system for greenhouse heating: an experimental study

    Microsoft Academic Search

    Onder Ozgener; Arif Hepbasli

    2005-01-01

    This study investigates the performance characteristics of a solar-assisted ground-source (geothermal) heat pump system (SAGSHPS) for greenhouse heating with a 50m vertical 32mm nominal diameter U-bend ground heat-exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22°C, 1226 degree days heating, base: 18°C), Turkey. Based upon the measurements made

  19. Coupled-resonator vertical-cavity laser

    NASA Astrophysics Data System (ADS)

    Choquette, Kent D.; Chow, Weng W.; Hou, Hong Q.; Geib, Kent M.; Hammons, B. E.

    1998-04-01

    The monolithic integration of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. We report the first electrically injected coupled resonator vertical-cavity laser diode and demonstrate novel characteristics arising form the cavity coupling, including methods for external modulation of the laser. A coupled mode theory is used model the output modulation of the coupled resonator vertical cavity laser.

  20. Modeling and experimental study of nucleate boiling on a vertical array of horizontal plain tubes

    SciTech Connect

    Ribatski, Gherhardt [Department of Mechanical Engineering, Escola de Engenharia de Sao Carlos (EESC), University of Sao Paulo (USP), Av. Trabalhador SanCarlense 400, Centro, Sao Carlos, SP (Brazil); Saiz Jabardo, Jose M. [Escola Politecnica Superior, Universidade da Coruna, Mendizabal s/n Esteiro, 15403 Ferrol, Coruna (Spain); da Silva, Evandro Fockink [Centro Federal de Educacao Tecnologica de Minas Gerais - CEFETMG, Unidade Divinopolis, R. Monte Santo, 319, Divinopolis, MG (Brazil)

    2008-09-15

    An investigation of nucleate boiling on a vertical array of horizontal plain tubes is presented in this paper. Experiments were performed with refrigerant R123 at reduced pressures varying from 0.022 to 0.64, tube pitch to diameter ratios of 1.32, 1.53 and 2.00, and heat fluxes from 0.5 to 40 kW/m{sup 2}. Brass tubes with external diameters of 19.05 mm and average roughness of 0.12 {mu}m were used in the experiments. The effect of the tube spacing on the local heat transfer coefficient along the tube array was negligible within the present range of experimental conditions. For partial nucleate boiling, characterized by low heat fluxes, and low reduced pressures, the tube positioning shows a remarkable effect on the heat transfer coefficient. Based on these data, a general correlation for the prediction of the nucleate boiling heat transfer coefficient on a vertical array of horizontal tubes under flooded conditions was proposed. According to this correlation, the ratio between the heat transfer coefficients of a given tube and the lowest tube in the array depends only on the tube row number, the reduced pressure and the heat flux. By using the proposed correlation, most of the experimental heat transfer coefficients obtained in the present study were predicted within {+-}15%. The new correlation compares reasonably well with independent data from the literature. (author)

  1. Waste heat

    SciTech Connect

    Moore, N.L.

    1985-07-01

    This is a survey of waste heat recovery in US industry. Future prospects depend on the price of fossil fuels. Fuel and energy consumption in the year 2000 is summarized. Areas of greatest growth in waste heat recovery will be in high-temperature recuperation, heat pumps and cogeneration. (DLC)

  2. Heat pumps

    Microsoft Academic Search

    R. D. Heap

    1979-01-01

    With increasing energy costs and changing cost relativities, potential heat pump applications deserve a thorough reassessment. Such a reassessment is the objective of this book. The topics covered include the general, historical, and theoretical background material; vapor compression equipment; general aspects of system design, with particular reference to the design of space heating systems employing heat pumps; domestic, commercial, and

  3. Vertical motion requirements for landing simulation

    NASA Technical Reports Server (NTRS)

    Bray, R. S.

    1973-01-01

    Tests were conducted to determine the significance of vertical acceleration cues in the simulation of the visual approach and landing maneuver. Landing performance measures were obtained for four subject pilots operating a visual landing simulation device which provides up to plus or minus 40 feet of vertical motion. Test results indicate that vertical motion cues are utilized in the landing task, and that they are particularly important in the simulation of aircraft with marginal longitudinal handling qualities. To assure vertical motion cues of the desired fidelity in the landing tasks, it appears that a simulator must have excursion capabilities of at least plus or minus 20 feet.

  4. On the Vertical Structure of Radiation-Dominated Accretion Disks

    E-print Network

    N. J. Turner

    2004-02-23

    The vertical structure of black hole accretion disks in which radiation dominates the total pressure is investigated using a three-dimensional radiation-MHD calculation. The domain is a small patch of disk centered 100 Schwarzschild radii from a black hole of 10^8 Solar masses, and the stratified shearing-box approximation is used. Magneto-rotational instability converts gravitational energy to turbulent magnetic and kinetic energy. The gas is heated by magnetic dissipation and by radiation damping of the turbulence, and cooled by diffusion and advection of radiation through the vertical boundaries. The resulting structure differs in several fundamental ways from the standard Shakura-Sunyaev picture. The disk consists of three layers. At the midplane, the density is large, and the magnetic pressure and total accretion stress are less than the gas pressure. In lower-density surface layers that are optically thick, the magnetic pressure and stress are greater than the gas pressure but less than the radiation pressure. Horizontal density variations in the surface layers exceed an order of magnitude. Magnetic fields in the regions of greatest stress are buoyant, and dissipate as they rise, so the heating rate declines more slowly with height than the stress. Much of the dissipation occurs at low column depth, and the interior is cooler and less radiation-dominated than in the Shakura-Sunyaev model with the same surface mass density and flux. The mean structure is convectively stable.

  5. Overspeed spoilers for vertical axis wind turbine

    Microsoft Academic Search

    R. S. Rangi; P. South

    1978-01-01

    An overspeed spoiler is described for vertical axis wind turbines of the type having straight or curved airfoil blades attached to a vertical shaft formed by a relatively thin flat blade shaped spoiler element hinge mounted on the trailing edge, leading edge, or at a central position of a portion of the airfoil section. The element has two portions one

  6. A method for quantifying vertical forest structure

    Microsoft Academic Search

    Penelope A Latham; Hans R Zuuring; Dean W Coble

    1998-01-01

    Vertical forest structure is an attribute of forests that is of interest to many disciplines and is consistently discussed in the context of ecosystem management. The vertical stratification of tree crowns is a forest attribute that influences both tree growth and understory community structure. Therefore, it should be considered when making management decisions that affect the structure of stands. However,

  7. Some empirical regularities on vertical restraints

    Microsoft Academic Search

    Xulia González

    2006-01-01

    Vertical restraints most often arise when an upstream firm wants to restrict the choices of a downstream distributor in order to increase profits. The aim of this paper is to analyze some empirical regularities in the motivations for vertical restraints. Firstly a simple theoretical framework is developed in which an upstream monopoly decides on the intermediate price and an effort

  8. The “vertical effect” in human squint amblyopia

    Microsoft Academic Search

    R. Sireteanu; W. Singer

    1980-01-01

    Grating acuity was tested in seven squint amblyopes as a function of orientation. In the squinting eyes of six unilateral amblyopes, the resolution for vertical gratings was much lower (by about 1\\/2 octave) than that of horizontal gratings. The non-amblyopic eyes of these subjects showed a normal “oblique effect”. In one bilateral amblyope the selective loss of resolution for vertical

  9. Lunar and Vertical Distribution of Myctophidae

    Microsoft Academic Search

    S. Tsarin

    2002-01-01

    The Myctophidae are the most numerous of the mesopelagic fishes in all oceans. Daily vertical migrations which connected with nutrition and energy exchange, are charac- teristic feature of the myctophids behavior. Myctophidae in main during the nighttime basic feed. There are two ecological groups of Myctophidae on the type of vertical migrations. (Some scientists select the third intermediate group). Superficial

  10. Theory of orientation, the visual vertical

    Microsoft Academic Search

    H. Schröer

    2002-01-01

    The book deals with the direction of orientation and the total acceleration in space. First in the book the visual vertical is explained. Then the direction of orientation on the earth's surface is determined. In the second chapter two planets are viewed. The observer is in the outer space, the visual vertical is calculated. The next chapter presents what happens

  11. Vertical Junction Type Organic Photovoltaic Cells

    Microsoft Academic Search

    Kouji Suemori; Takahiro Miyata; Masahiro Hiramoto; Masaaki Yokoyama

    2004-01-01

    Vertical junction type organic photovoltaic cells having a pn junction formed perpendicularly to a light irradiated surface were fabricated. Short-circuit photocurrent density of 8.5 mA\\\\cdotcm-2 and power conversion efficiency of 0.54% were observed under simulated solar illumination. The large photocurrent density is attributed to the light collection effect via the transparent vertical layer.

  12. Origami Multistabilty: From Single Vertices to Metasheets

    E-print Network

    Scott Waitukaitis; Rémi Menaut; Bryan Gin-ge Chen; Martin van Hecke

    2014-09-09

    We explore the surprisingly rich energy landscape of origami-like folding planar structures. We show that the configuration space of rigid-paneled degree-4 vertices, the simplest building blocks of such systems, consists of at least two distinct branches meeting at the flat state. This suggests that generic vertices are at least bistable, but we find that the nonlinear nature of these branches allows for vertices with as many as five distinct stable states. In vertices with collinear folds and/or symmetry, more branches emerge leading to up to six stable states. Finally, we introduce a procedure to tile arbitrary 4-vertices while preserving their stable states, thus allowing the design and creation of multistable origami metasheets.

  13. Heat fluxes in Drake Passage

    NASA Astrophysics Data System (ADS)

    Ferrari, Ramiro; Prvost, Christine; Sennéchael, Nathalie; Sekma, Hela; Park, Young-Hyang; Lee, Jae Hak

    2013-04-01

    Determining the processes responsible for the Southern Ocean heat balance is fundamental to our understanding of the weather and climate systems. Therefore, in the last decades, various studies aimed at analyzing the major mechanisms of the oceanic poleward heat flux in this region. Previous works stipulated that the cross-stream heat flux due to the mesoscale transient eddies was responsible for the total meridional heat transport across the Antarctic Circumpolar Current (ACC). Several numerical modelling and current meters data studies have recently challenged this idea. These showed that the heat flux due to the mean flow in the southern part of the Antarctic Circumpolar Current could be larger than the eddy heat flux contribution by two orders of magnitude [Sekma et al., 2012]. Eddy heat flux and heat flux by the mean flow distributions of were examined in Drake Passage. The in situ velocity and temperature time series used to estimate the poleward heat flux in Drake Passage were obtained at five mooring sites across the Yaghan Basin (from January 2006 to March 2009), and at four mooring sites across Ona Basin (from February 2006 to April 2008). In the northern part of Antarctic Circumpolar Current (Yaghan Basin), the computed eddy heat flux was significant only in the northern branch of the Subantarctic Front (˜90 kW m-2). The poleward eddy heat flux on the southern flank of the ACC (Ona Basin) was significant across the Polar Front and Southern Antarctic Circumpolar Current Front (˜10 kW m-2). However, eddy activity on the southern flank of the ACC is too weak to transport sufficient heat poleward to accomplish the Southern Ocean heat balance required task. The mean velocity vectors were observed to rotate with depth indicating consistent downwelling except at mooring located in the center of Ona Basin. A rotation of the mean velocity vector with depth is associated with a cold or warm advection in the entire water column. The estimated poleward heat flux by the mean flow (varying from 989 kW m-2 to 101 kW m-2 depending the mooring sites) was larger than the eddy heat flux by as much as one order of magnitude. The vertical structure of the mean flux in several topographically constricted passages is seen as the major responsible of the Southern Ocean heat balance.

  14. Mechanical Engineering Laboratory of Heat and Mass Transfer

    E-print Network

    Diggavi, Suhas

    of condensation heat transfer in vertical minichannels g g Motivation Two phase flow cooling, especially within the prediction methods. The local condensation heat transfer behavior of two new refrigerants(R236fa and R1234ze to be implemented in the power electronics system. Test facility Experimental results 1 y schematic diagram of test

  15. MJO Signals in Latent Heating: Results from TRMM Retrievals

    Microsoft Academic Search

    Chidong Zhang; Jian Ling; Samson M. Hagos; Wei-Kuo Tao; Steve Lang; Yukari N. Takayabu; Shoichi Shige; Masaki Katsumata; William S. Olson; Tristan L'Ecuyer

    2010-01-01

    Four Tropical Rainfall Measuring Mission (TRMM) datasets of latent heating were diagnosed for signals in the Madden-Julian Oscillation (MJO). In all four datasets, vertical structures of latent heating are dominated by two components, one deep with its peak above the melting level and one shallow with its peak below. Profiles of the two components are nearly ubiquitous in longitude, allowing

  16. Investigation of the heat pipe arrays for convective electronic cooling 

    E-print Network

    Howard, Alicia Ann Harris

    1993-01-01

    A combined experimental and analytical investigation was conducted to evaluate a heat pipe convective cooling device consisting of sixteen small copper/water heat pipes mounted vertically in a 4x4 array 25.4 mm square. The analytical portion...

  17. Boiling helium heat transfer characteristics in narrow cooling channel

    Microsoft Academic Search

    M. Nishi; T. Ando; T. Hiyama; T. Kato; S. Shimamoto

    1983-01-01

    For design of a stable superconducting magnet with pool cooling method, the size of the cooling channel is one of the important factors to determine its overall current density. The authors measured the steady state boiling helium heat transfer characteristics in a 600 mm long vertical cooling channel. The result shows that heat transfer characteristics in film boiling region do

  18. Evaluation of Generation Mechanism of Vertical Cracks in Top Coat of TBCs During APS Deposition by Laser AE Method

    NASA Astrophysics Data System (ADS)

    Ito, K.; Kuriki, H.; Araki, H.; Kuroda, S.; Enoki, M.

    2015-06-01

    Vertical cracks can be generated in the top coat of thermal barrier coatings (TBCs) deposited by atmospheric plasma spraying (APS). Since they are known to improve the durability of TBCs such as in the case of dense vertically cracked TBC, clarification of the mechanism and the criteria of cracking are very important. In this study, generation of such vertical cracks was monitored during APS process by laser acoustic emission (AE) method, which is an in situ, non-contact, and non-destructive technique. Temperature was also monitored inside and on the surface of a specimen during APS process for estimation of the temperature field in the top coat. Results of the AE and temperature monitoring were combined to evaluate the relationship between cracking and thermal stress in the top coat. Most of the AE events due to the generation of vertical cracks were detected during rapid heating of the surface of the top coat by the heat flux from the torch. It showed that the vertical cracks were induced due to the tensile stress caused by the temperature difference in the top coat from the rapid heating. Furthermore, the estimated critical thermal stress for vertical cracking from the monitoring results was consistent with a previously reported strength of YSZ coating deposited by thermal spray.

  19. Evaluation of Generation Mechanism of Vertical Cracks in Top Coat of TBCs During APS Deposition by Laser AE Method

    NASA Astrophysics Data System (ADS)

    Ito, K.; Kuriki, H.; Araki, H.; Kuroda, S.; Enoki, M.

    2015-05-01

    Vertical cracks can be generated in the top coat of thermal barrier coatings (TBCs) deposited by atmospheric plasma spraying (APS). Since they are known to improve the durability of TBCs such as in the case of dense vertically cracked TBC, clarification of the mechanism and the criteria of cracking are very important. In this study, generation of such vertical cracks was monitored during APS process by laser acoustic emission (AE) method, which is an in situ, non-contact, and non-destructive technique. Temperature was also monitored inside and on the surface of a specimen during APS process for estimation of the temperature field in the top coat. Results of the AE and temperature monitoring were combined to evaluate the relationship between cracking and thermal stress in the top coat. Most of the AE events due to the generation of vertical cracks were detected during rapid heating of the surface of the top coat by the heat flux from the torch. It showed that the vertical cracks were induced due to the tensile stress caused by the temperature difference in the top coat from the rapid heating. Furthermore, the estimated critical thermal stress for vertical cracking from the monitoring results was consistent with a previously reported strength of YSZ coating deposited by thermal spray.

  20. Using Exergy Analysis Methodology to Assess the Heating Efficiency of an Electric Heat Pump

    E-print Network

    Ao, Y.; Duanmu, L.; Shen, S.

    2006-01-01

    ., Liu X.Y. Introduction of the Geothermal Heat Pump Laboratory Study [J]. Modern Air-conditioning, 2001, 3(8): 11-13. [3]Li Y.D., Zhang X. Laboratory Study to the Start Property of the System Running for An Underground Earth Heat Pump [J]. The HVAC... Journal, 2001, 31(1): 17-20. [4]Li X.G., Zhao J. The Study of Heating and Cooling Property of the Vertical Coil Heat Pump [J]. Solar Energy Journal, 2002, 23(6): 684-686. [5]Wang J.G., Ma Y.T. The Simulation of the System Operation to the Geothermal...

  1. Heat Transfer

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students explore heat transfer and energy efficiency using the context of energy efficient houses. They gain a solid understanding of the three types of heat transfer: radiation, convection and conduction, which are explained in detail and related to the real world. They learn about the many ways solar energy is used as a renewable energy source to reduce the emission of greenhouse gasses and operating costs. Students also explore ways in which a device can capitalize on the methods of heat transfer to produce a beneficial result. They are given the tools to calculate the heat transferred between a system and its surroundings.

  2. Arrangement in a heat recovery unit

    SciTech Connect

    Gustavsson, K.A.; Jansson, K.A.; Kruse, R.A.

    1983-03-22

    A heat recovery unit is adapted for installing in a cookery cupboard or the like space in a dwelling. Within a casing the unit has a lamella heat exchanger, which is arranged on one corner edge and has two of its defining surfaces provided with openings for passages facing upwards and two downwards. The heat exchanger has its end walls oriented in vertical planes. It is adapted for heating supply air through heat take-up from exhaust air. Four vertical wall portions form a cross above the heat exchanger, thus providing four chambers for the ingoing and outgoing air flows. By means of portions airtightly sealed against the casing and wall portions the heat exchanger is divided into two portions, each having a cross-stream course between supply air and exhaust air, with its passages for supply air and exhaust air arranged in series with the corresponding passages of the other portion. The heat exchanger is removable as a unit after opening the front of the casing.

  3. Establishment, Verification and Application of a Co rrelation to Predict the Maximum Heat Flux of a Horizontal Closed-Loop Pulsating Heat Pipe

    Microsoft Academic Search

    Niti Kammuang-Lue; Teerasak Hudakorn; Pradit Terdtoon

    2010-01-01

    Problem statement: In heat pipe design, it was very important to be s ure that the desired heat pipe would not operate in the MHF state. In th e case of a vertical CLPHP, the MHF state and maximum heat flux could be predicted by using the correlation, while, in the case of a horizontal CLPHP, there had been no

  4. A vertically integrated model with vertical dynamics for CO2 storage

    NASA Astrophysics Data System (ADS)

    Guo, Bo; Bandilla, Karl W.; Doster, Florian; Keilegavlen, Eirik; Celia, Michael A.

    2014-08-01

    Conventional vertically integrated models for CO2 storage usually adopt a vertical equilibrium (VE) assumption, which states that due to strong buoyancy, CO2 and brine segregate quickly, so that the fluids can be assumed to have essentially hydrostatic pressure distributions in the vertical direction. However, the VE assumption is inappropriate when the time scale of fluid segregation is not small relative to the simulation time. By casting the vertically integrated equations into a multiscale framework, a new vertically integrated model can be developed that relaxes the VE assumption, thereby allowing vertical dynamics to be modeled explicitly. The model maintains much of the computational efficiency of vertical integration while allowing a much wider range of problems to be modeled. Numerical tests of the new model, using injection scenarios with typical parameter sets, show excellent behavior of the new approach for homogeneous geologic formations.

  5. Effect of electron thermal motion on plasma heating in a magnetized inductively coupled plasma

    SciTech Connect

    Aman-ur-Rehman; Pu Yikang [Department of Engineering Physics, Tsinghua University, 100084 Beijing, China and Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore Islamabad (Pakistan); Department of Engineering Physics, Tsinghua University, 100084 Beijing (China)

    2007-06-15

    Power absorbed inside the magnetized inductively coupled plasma (MICP) is calculated using three different warm MICP models and is then compared with the result of the cold MICP model. The comparison shows that in the propagating region ({omega}< vertical bar {omega}{sub e} vertical bar), under the cavity resonance conditions, warm plasma heating S{sub warm} is significantly less than the cold plasma heating S{sub cold}, unless the distance traveled by the electrons due to their thermal motion, during the effective wave period, becomes significantly less than the wavelength of the cavity wave. Furthermore, in the propagating region, when {omega}{approx_equal} vertical bar {omega}{sub e} vertical bar, there appears a valley on the plot of {eta}({omega})=S{sub warm}/S{sub cold} versus {omega} showing the negative effect of electron thermal motion on plasma heating. This valley widens and gets smoother with an increase in the plasma length. In the nonpropagating region ({omega}> vertical bar {omega}{sub e} vertical bar), the maximum value of {eta}({omega}) exists when {omega}- vertical bar {omega}{sub e} vertical bar {approx_equal}v{sub th}/{delta}, showing that, in the presence of the external magnetic field, the thermal motion of the electrons leads to a Doppler shift of the frequencies, at which collisionless heating is the dominant mode of electron heating. Furthermore, in the nonpropagating region, when {omega}{approx_equal} vertical bar {omega}{sub e} vertical bar, the skin depth of the right circularly polarized electric field decreases with magnetic field. This decrease in the skin depth results in an increase of collisionless heating under the Doppler-shifted wave particle resonant condition of {omega}- vertical bar {omega}{sub e} vertical bar {approx_equal}v{sub th}/{delta}. It is also observed that, for large plasma length, the results of all the three warm MICP models are consistent with each other.

  6. Wake interference for a heated oscillating cylinder

    NASA Technical Reports Server (NTRS)

    Mceligot, D. M.; Smith, S. B.; Verity, R. L.

    1982-01-01

    Penney and Jefferson (1966) have studied heat transfer from an oscillating, horizontal wire. The present investigation has the objective to determine the governing parameters which indicate when interaction between an oscillating circular cylinder and its wake will reduce the apparent heat transfer coefficient in quasi-steady conditions, taking into account, if possible, also the determination of the approximate magnitude of the reduction. A definition is provided of a nondimensional vertical mass flux, representing the induced flow due to heating of the stagnant fluid. It is hypothesized that the flux is related to a natural convection parameter which describes the heating of the wake. For oscillation of a circular cylinder in air under the conditions studied, it is found that the application of a cross-flow correlation in a quasi-steady, transient analysis predicts heat transfer parameters in close agreement with experiment over a certain range, provided interaction with the heated wake is avoided.

  7. A Mode ling Approach To Design Of A Ground-Source Heat Pump Bridge Deck Heating System

    Microsoft Academic Search

    Andrew Chiasson; Jeffrey D. Spitler

    This paper describes the approach taken to design a hydronic snow melting system for a bridge deck on an interstate highway in Oklahoma where a vertical borehole, closed-loop ground-source heat pump system is to be used as an energy efficient means to provide the heating requirement. It is proposed to use the bridge deck as a solar collector in the

  8. GROUND WATER PROTECTION ISSUES WITH GEOTHERMAL HEAT PUMPS

    SciTech Connect

    ALLAN,M.L.; PHILIPPACOPOULOS,A.J.

    1999-10-01

    Closed loop vertical boreholes used with geothermal heat pumps are grouted to facilitate heat transfer and prevent ground water contamination. The grout must exhibit suitable thermal conductivity as well as adequate hydraulic sealing characteristics. Permeability and infiltration tests were performed to assess the ability of cementitious grout to control vertical seepage in boreholes. It was determined that a superplasticized cement-sand grout is a more effective borehole sealant than neat cement over a range of likely operational temperatures. The feasibility of using non-destructive methods to verify bonding in heat exchangers is reviewed.

  9. Supermarket with Ground Coupled Carbon Dioxide Refrigeration Plant

    E-print Network

    Rehault, N.

    2012-01-01

    on supermarkets, energy and greenhouse gases 2. Energy efficient supermarket concept and goals 3. Results 4. Conclusion and outlook ? Fraunhofer ISE 3 Why do we need energy efficient supermarkets? ? Supermarkets create greenhouse gases ?Supermarket... - 42% - 33% ? Fraunhofer ISE 19 Lessons learned and outlook: ? New concept reached 20% energy savings after 1 year ? Greenhouse gas emissions cut by over 30% after 1 year through the use of CO2 as refrigerant ? Integrated concepts have future...

  10. Composite resonator vertical cavity laser diode

    SciTech Connect

    Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

    1998-05-01

    The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

  11. Surface tension profiles in vertical soap films

    NASA Astrophysics Data System (ADS)

    Adami, N.; Caps, H.

    2015-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

  12. Vertical transmission of Salmonella paratyphi A.

    PubMed

    Raveendran, R; Wattal, C; Sharma, A; Kler, N; Garg, P; Gujral, K; Khera, N

    2007-08-01

    Neonatal enteric fever is a rare but life-threatening illness. Patients may present with varying severity, Salmonella enterica serotype Typhi causing more severe illness than Salmonella enterica serotype Paratyphi A. Salmonella enterica serotype Paratyphi A is considered to cause milder infection with fewer complications. We report a rare case of vertical transmission of Salmonella enterica serotype Paratyphi A with severe complications and high mortality. Even though there are case reports of vertical transmission of Salmonella enterica serotype Typhi, to our knowledge, this is the first case report of vertical transmission of Salmonella enterica serotype ParatyphiA. The role of blood culture in accurate diagnosis and treatment is also discussed. PMID:17785907

  13. Dominant vertices in regulatory networks dynamics

    NASA Astrophysics Data System (ADS)

    Luna, Beatriz; Ugalde, Edgardo

    2008-11-01

    Discrete-time regulatory networks are dynamical systems on directed graphs with a structure that is inspired on natural systems of interacting units. Using a notion of determination between vertices, we define sets of dominant vertices, and we prove that in the asymptotic regime, the projection of the dynamics on a dominant set allows us to determine the state of the whole system at all times. We provide an algorithm to find sets of dominant vertices, and we test its accuracy on several examples. We also explore the possibility of using the dominant set characteristics as a measure of the structural complexity of networks.

  14. On the vertical thermal structure of Io's atmosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Zhu, Xun; Summers, Michael F.

    1994-01-01

    A radiative-thermal conduction model for the vertical thermal structure of Io's atmosphere is developed with solar heating by SO2 absorption in UV and near-IR bands and non-local thermodynamic equilibrium (LTE) cooling by SO2 nu(sub 1), nu(sub 2), nu(sub 3), vibrational bands and rotational lines. The model predicts the existence of a mesopause in Io's atmosphere when the surface pressure exceeds approximately 10 nbar. The radiative time constant for establishing a mesosphere/mesopause on Io is only approximately 20 min, whereas the thermospheric radiative time constant is about 1 hr. These time constants are significantly shorter than the diurnal time scale and competitive with dynamic time scales. In the thermosphere when solar UV heating dominates, the asymptotic thermospheric temperature is approximately 270 K, only 140 K greater than the surface temperature because at high altiudes non-LTE cooling by SO2 rotation lines exceeds cooling in the nu(sub 2) virbrational band. Solar-heating-only modles are incapable of generating warm enough atmospheres to satisfy the observational inferences from UV and especially millimeter-wave meausrements. Joule heating driven by the penetration of Jupiter's corotational electric field into Io's conducting ionosphere is demonstrated to be the dominant heating mechanism in the subnanobar regions of Io's atmosphere with tempertures ranging from 150 to 1000 K as a function of decreasing pressure from 1 to 0.1 nbar, The asymoptotic thermospheric temperature can attain a value as high as 1800 K.

  15. Heat Problems.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…

  16. Heat stroke.

    PubMed

    Leon, Lisa R; Bouchama, Abderrezak

    2015-04-01

    Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling. PMID:25880507

  17. Nanofluid impingement jet heat transfer

    NASA Astrophysics Data System (ADS)

    Zeitoun, Obida; Ali, Mohamed

    2012-02-01

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters.

  18. Nanofluid impingement jet heat transfer.

    PubMed

    Zeitoun, Obida; Ali, Mohamed

    2012-01-01

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters. PMID:22340669

  19. Vertical Glider Robots for Subsea Equipment Delivery

    E-print Network

    Reed, Brooks L.

    2011-01-01

    We have developed an underwater vehicle that offers significant performance improvements over existing sub sea elevators. Our Vertical Glider Robot falls under its own weight to a precise location on the seafloor, employing ...

  20. Vertical-axis wind-turbine program

    SciTech Connect

    Braasch, R.H.

    1981-01-01

    During the interval since the Fourth Biennial Wind Energy Conference, the vertical axis wind turbine program has experienced significant progress. The purpose of this paper is to review that progress in aerodynamics research, structural dynamics research, and machine development.

  1. Vertical wind estimation from horizontal wind measurements

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D.

    1994-01-01

    The objective of this study was to assess the ability of simple vertical wind models to improve the hazard prediction capability of an airborne Doppler sensor in a realistic microburst environment. The results indicate that in the altitude region of interest (at or below 300 meters), both the linear and empirical vertical wind models improved the hazard estimate. The radar simulation study showed that the magnitude of the performance improvement was altitude dependent. The altitude of maximum performance improvement occurred at about 300 meters. At the lower altitudes the percent improvement was minimized by the diminished contribution of the vertical wind. The vertical hazard estimate errors from flight tests were less than those of the radar simulation study.

  2. Subsurface imaging with reverse vertical seismic profiles

    E-print Network

    Krasovec, Mary L. (Mary Lee), 1972-

    2001-01-01

    This thesis presents imaging results from a 3D reverse vertical seismic profile (RVSP) dataset measured at a hydrocarbon bearing pinnacle reef in northern Michigan. The study presented many challenges in seismic data ...

  3. Stability of Granular Materials under Vertical Vibrations

    E-print Network

    Deng, Rensheng

    The influence of periodic vibrations on the granular flow of materials is of great interests to scientists and engineers due to both theoretical and practical reasons. In this paper, the stability of a vertically vibrated ...

  4. Vertically Aligned Nanocomposites in Magnetic Thin Films 

    E-print Network

    Abdel-Raziq, Haron

    2013-02-11

    With the advent of ferromagnetic materials for magnetic memory among other applications, increased attention has been given to understanding the properties of these ferromagnets. Here, a vertically aligned nanocomposite (VAN) system is examined...

  5. 23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL BRACING DETAIL. VIEW TO SOUTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  6. 30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND LOWER CHORD DETAIL OF DECK TRUSS. VIEW TO NORTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  7. A correction method for heated length effect in critical heat flux prediction

    Microsoft Academic Search

    Yong Ho Lee; Won-Pil Baek; Soon Heung Chang

    2000-01-01

    A new correction method is developed for the effect of the length-to-diameter (L\\/D) ratio on critical heat flux (CHF) by applying artificial neural networks and conventional regression techniques to the KAIST CHF data base for water flow in uniformly-heated, vertical round tubes. It consists of two parts: (a) a threshold L\\/D over which the length effect becomes negligible; and (b)

  8. Modeling of condensation heat transfer for a PRHRS heat exchanger in a SMART-P plant

    Microsoft Academic Search

    Kwon-Yeong Lee; Moo Hwan Kim

    2008-01-01

    A theoretical model using a heat and mass transfer analogy and a simple model using Lee and Kim's [Lee, K.-Y., Kim, M.H., 2008a. Experimental and empirical study of steam condensation heat transfer with a noncondensable gas in a small-diameter vertical tube. Nucl. Eng. Des. 238, 207–216] correlation were developed to investigate steam condensation in the presence of a noncondensable gas

  9. Boiling Heat Transfer for Freon R21 in Rectangular Minichannel

    Microsoft Academic Search

    V. V. Kuznetsov; A. S. Shamirzaev

    2007-01-01

    In this paper, we study the boiling heat transfer of upward flow of R21 in a vertical mini-channel with a size of 1.6 × 6.3 mm. The heat transfer coefficient was measured as a function of heat flux for a wide range of vapor quality and for two levels of mass flow rate, G = 215 kg\\/ms and G =

  10. Seismic vertical array analysis for phase decomposition

    NASA Astrophysics Data System (ADS)

    Yoshida, Kunikazu; Sasatani, Tsutomu

    2008-08-01

    We propose a vertical array analysis method that decomposes complex seismograms into body and surface wave time histories by using a velocity structure at the vertical array site. We assume that the vertical array records are the sum of vertically incident plane P and S waves, and laterally incident Love and Rayleigh waves. Each phase at the surface is related to that at a certain depth by the transfer function in the frequency domain; the transfer function is obtained by Haskell's matrix method, assuming a 1-D velocity structure. Decomposed P, S and surface waves at the surface are estimated from the vertical array records and the transfer functions by using a least-squares method in the frequency domain; their time histories are obtained by the inverse Fourier transform. We carried out numerical tests of this method based on synthetic vertical array records consisting of vertically incident plane P and S waves and laterally incident plane Love and Rayleigh waves. Perfect results of the decomposed P, S, Love and Rayleigh waves were obtained for synthetic records without noise. A test of the synthetic records in which a small amount of white noise was added yielded a reasonable result for the decomposed P, S and surface waves. We applied this method to real vertical array records from the Ashigara valley, a moderate-sized sedimentary valley. The array records from two earthquakes occurring at depths of 123 and 148 km near the array (epicentral distance of about 31 km) exhibited long-duration later phases. The analysis showed that duration of the decomposed S waves was a few seconds and that the decomposed surface waves appeared a few seconds after the direct S-wave arrival and had very long duration. This result indicated that the long-duration later phases were generated not by multireflected S waves, but by basin-induced surface waves.

  11. Vertically aligned biaxially textured molybdenum thin films

    Microsoft Academic Search

    Rahul Krishnan; Michael Riley; Sabrina Lee; Toh-Ming Lu

    2011-01-01

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85º with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation.

  12. Triaxial thermopile array geo-heat-flow sensor

    DOEpatents

    Carrigan, Charles R. (Tracy, CA); Hardee, Harry C. (Albuquerque, NM); Reynolds, Gerald D. (Tijeras, NM); Steinfort, Terry D. (Tijeras, NM)

    1992-01-01

    A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers arranged in a vertical string. The transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings.

  13. Competitive co-existence of vertically and horizontally transmitted parasites

    E-print Network

    Lively, Curt

    of vertically transmitted bacteria within the female reproductive organs of many arthropods, especially blood by systemic fungal endophytes that are vertically transmitted through seeds (Schardl, 1996). Theory suggests

  14. Heat collector

    DOEpatents

    Merrigan, Michael A. (Santa Cruz, NM)

    1984-01-01

    A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

  15. MODELLING AND ASSESSMENT OF GROUND-SOURCE HEAT PUMP SYSTEMS USING EXERGOECONOMIC ANALYSIS FOR BUILDING APPLICATIONS

    Microsoft Academic Search

    Onder Ozgener; Arif Hepbasli; Ibrahim Dincer; Marc A. Rosen

    Ground source heat pumps (GSHPs) are modelled, analyzed based on exergy, cost, energy and mass, and evaluated exergoeconomically. In this regard, the system considered here is a GSHP heating system with a 50 m vertical U-bend ground heat exchanger having a 32 mm nominal diameter. This system was designed and installed at the Solar Energy Institute, Ege University, Izmir, Turkey.

  16. Experimental investigation on the heat transfer of an impinging inverse diffusion flame

    Microsoft Academic Search

    T. K. Ng; C. W. Leung; C. S. Cheung

    2007-01-01

    This paper presents the results of an experimental study on the heat transfer characteristics of an inverse diffusion flame (IDF) impinging vertically upwards on a horizontal copper plate. The IDF burner used in the experiment has a central air jet surrounded circumferentially by 12 outer fuel jets. The heat flux at the stagnation point and the radial distribution of heat

  17. Incipient buoyant thermal convection in a vertical cylindrical annulus

    SciTech Connect

    Littlefield, D.L. (US Army Ballistic Research Lab., Aberdeen Proving Ground, MD (USA)); Desai, P.V. (Georgia Inst. of Tech., Atlanta (USA))

    1990-11-01

    The incipient buoyant thermal convection in a vertical cylindrical annulus when heated from below is examined. The ends are assumed to be free, and the sidewalls perfectly conducting. The temperature needed to initiate fluid motion is expressed nondimensionally in terms of the Rayleigh number. The analytical conflict that arises for annuli of infinite aspects ratios due to insufficient independent boundary conditions is resolved. Calculations for the critical Rayleigh numbers are presented for a variety of geometries, and the corresponding velocity and temperature perturbations are also shown. The number of cells increases as the aspect and radius ratio decrease with a strong bias towards the development of azimuthally varying cells. These changes in cellular behavior are expected based on physical justifications and comparisons with previous studies.

  18. Nonlinear interactions between convection, rotation and flows with vertical shear

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.; Somerville, R. C. J.

    1986-01-01

    The effects of a mean flow with vertical shear on the convective motions in a rotating layer are examined using a three-dimensional and time-dependent numerical model. In the absence of rotation, the convective motions are shown to be dominated by the shear flow when the Richardson number becomes greater than about -1.0. Both heat and momentum are carried down their respective gradients. For rotating cases with vertical rotation vectors, the Coriolis force turns the flow induced by the convection to produce a more complicated shear that changes direction with height. For rotating cases with tilted rotation vectors, the results depend on the direction of the shear. When the imposed flow is in the opposite direction, the convection motions are less energetic and are even suppressed entirely when the shear is strong. When the imposed flow is in the same direction, as that produced by the rotation, the convective motions are enhanced and a countergradient flux of momentum can be produced.

  19. CFD simulation of convective flow boiling of refrigerant in a vertical annulus

    Microsoft Academic Search

    Boštjan Kon?ar; Eckhard Krepper

    2008-01-01

    In this paper a convective flow boiling of refrigerant R-113 in a vertical annular channel has been simulated by a CFD (Computational Fluid Dynamics) code CFX. The Arizona State University (ASU) boiling flow experiments [Roy, R.P., Kang, S., Zarate, J.A., Laporta, A., 2002. Turbulent subcooled boiling flow—experiments and simulations. J. Heat Transfer 124, 73–93] in annular channel were used to

  20. Design And Construction Of A Large, Vertical Axis Diamond Turning Machine

    NASA Astrophysics Data System (ADS)

    Donaldson, R. R.; Patterson, S. R.

    1983-12-01

    A 64-inch swing, vertical spindle axis precision lathe has been constructed. The machine incorporates a multiple-path laser feedback system, capacitance gauges, a 32-bit computer and capstan drives to provide two axes of tool motion in a 32-inch radius by 20-inch length working volume. Dimensional stability of critical components is achieved through the use of low coefficient-of-thermal-expansion materials and temperature-controlled heat sinks. Projected accuracy of the machine is approximately one microinch rms.

  1. Comprehensive numerical modeling of vertical-cavity surface-emitting lasers

    Microsoft Academic Search

    G. Ronald Hadley; K. L. Lear; M. E. Warren; K. D. Choquette; J. W. Scott; S. W. Corzine

    1996-01-01

    We present a comprehensive numerical model for vertical-cavity surface-emitting lasers that includes all major processes affecting cw operation of axisymmetric devices. In particular, our model includes a description of the 2-D transport of electrons and holes through the cladding layers to the quantum well(s), diffusion and recombination of these carriers within the wells, the 2-D transport of heat throughout the

  2. Properties of Precipitation and In-Cloud Vertical Motion in a Global Nonhydrostatic Aquaplanet Experiment

    Microsoft Academic Search

    Tomoe NASUNO; Masaki Satoh

    2011-01-01

    To gain insight into properties of in-cloud vertical motion and precipitation production in the tropics, three-dimensional outputs from an aquaplanet experiment using a 3.5-km mesh global cloud-system resolving model (GCRM) were analyzed. Probability distributions of precipitation and latent heating in the 10°N–10°S domain are evaluated in comparison with Tropical Rainfall Measurement Mission (TRMM) observations. Despite biases of generally higher precipitation

  3. Heat pipe waste heat recovery boilers

    Microsoft Academic Search

    D. A. Littwin; J. McCurley

    1981-01-01

    The use of heat pipes as transport devices in waste heat recovery boilers is examined. Test results show that heat pipes can efficiently extract heat from the hot gas stream and transfer it inside the pressure vessel for the steam generation process. The benefits of incorporating heat pipes into the design of waste heat recovery boilers include a highly compact

  4. Latent heat in soil heat flux measurements

    Microsoft Academic Search

    J. L. Heitman; R. Horton; T. J. Sauer; T. S. Ren; X. Xiao

    2010-01-01

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, there remains uncertainty about what comprises soil heat flux and how surface and subsurface heat fluxes

  5. Dissociated vertical deviation and eye torsion: Relation to disparity-induced vertical vergence.

    PubMed

    Van Rijn, L J; Simonsz, H J; Tusscher, M P

    1997-01-01

    We studied the relation between vertical eye movements and binocular torsion in five subjects with dissociated vertical deviation (DVD). During trials, subject viewed a well illuminated Snellen letter chart, with both eyes uncovered during 4 seconds, Subsequently, DVD was induced by covering one eye during 4 seconds. Finally, both eyes were uncovered during 4 seconds. Several trials were recorded for each subject and covered eye. Eye movements were measured with scleral coils. We found that in all subjects, the vertical divergence followed an exponential course with a time constant of 0.67 ± 0.14 seconds on average. In three of the five subjects this vertical divergence was associated with binocular torsion (cycloversion), partly, in the form of a cycloversional nystagmus. The time course of the vertical divergence as well as the direction and nystagmic nature of the cycloversion was similar to the behaviour that was previously observed in disparity induced vertical vergence in normal subjects. In two of the subjects, the torsion that was associated with the vertical divergence was monocular. Our results indicate that DVD and disparity induced vertical vergence share the same characteristics. In addition, they demonstrate that extorsion associated with the elevation in DVD possibly but not necessarily points at a dissociated torsional deviation. PMID:21314389

  6. Binocular contributions to linear vertical vection.

    PubMed

    Allison, Robert S; Ash, April; Palmisano, Stephen

    2014-01-01

    Compelling illusions of self-motion, known as vection, can be produced in a stationary observer by visual stimulation alone. The role of binocular vision and stereopsis in these illusions was explored in a series of three experiments. Previous research had provided evidence of stereoscopic enhancements for linear vection in depth (e.g., Palmisano, 1996, 2002). Here we examined for the first time the effects of binocular vision and stereopsis on linear vertical vection. Vertical vection was induced by the upward or downward translation of large stereoscopic surfaces. These surfaces were horizontally oriented depth corrugations produced by disparity modulation of patterns of persistent or short lifetime dot elements. We found that binocular viewing of such surfaces significantly increased the magnitudes and decreased the onset delays of vertical vection. Experiments utilizing short lifetime dot stereograms demonstrated that these particular binocular enhancements of vection were due to the motion of stereoscopically defined features. PMID:25761282

  7. Vertical vibration analysis for elevator compensating sheave

    NASA Astrophysics Data System (ADS)

    Watanabe, Seiji; Okawa, Takeya; Nakazawa, Daisuke; Fukui, Daiki

    2013-07-01

    Most elevators applied to tall buildings include compensating ropes to satisfy the balanced rope tension between the car and the counter weight. The compensating ropes receive tension by the compensating sheave, which is installed at the bottom space of the elevator shaft. The compensating sheave is only suspended by the compensating ropes, therefore, the sheave can move vertically while the car is traveling. This paper shows the elevator dynamic model to evaluate the vertical motion of the compensating sheave. Especially, behavior in emergency cases, such as brake activation and buffer strike, was investigated to evaluate the maximum upward motion of the sheave. The simulation results were validated by experiments and the most influenced factor for the sheave vertical motion was clarified.

  8. Shocks in vertically oscillated granular layers J. Bougie, Sung Joon Moon, J. B. Swift, and Harry L. Swinney

    E-print Network

    Texas at Austin. University of

    Shocks in vertically oscillated granular layers J. Bougie, Sung Joon Moon, J. B. Swift, and Harry L at the point where a fluid encounters an obstacle, a compression wave front is formed near the object and steepens to form a shock. In an ideal fluid with no viscosity or heat conduction, the wave front steepens

  9. MODELS OF VERTICALLY STRATIFIED TWO-PHASE ISM DISKS WITH MRI-DRIVEN TURBULENCE Robert A. Piontek1,2

    E-print Network

    , vertical gravity, and a radiative cooling function for atomic gas. This allows us to study that for realistic heating and cooling functions the atomic ISM could exist in two distinct stable phases in pressure by SN blast waves that overrun a significant fraction of the volume. Many elements of this ``three

  10. Vertical Vergence Adaptation Produces an Objective Vertical Deviation That Changes With Head Tilt

    PubMed Central

    Irsch, Kristina; Guyton, David L.; Ramey, Nicholas A.; Adyanthaya, Rohit S.; Ying, Howard S.

    2013-01-01

    Purpose. To document the cyclovertical ocular motor mechanism used for vertical fusion in healthy subjects, and to explore whether vertical vergence training in healthy individuals can produce objectively confirmed vertical deviations that change with head tilt, revealing a basic mechanism that can produce a pattern of misalignment in an otherwise normal ocular motor system that is similar to superior oblique muscle paresis (SOP). Methods. Seven subjects with normal orthoptic examinations were adapted to vertical image disparities using our tilting haploscopic eye-tracking apparatus presenting concentric circle targets without torsional cues. Static eye positions were recorded with head straight and when tilted 45 degrees to the left and right, during both binocular and monocular viewing. Results. Vertical fusional vergence was accompanied by a cycloversion, with the downward-moving eye intorting and the upward-moving eye extorting, implicating primary involvement of the oblique extraocular muscles. After adaptation to the slowly increasing vertical target separation, all subjects developed a temporary vertical deviation in the straight ahead position that increased with head tilt to one side and decreased with head tilt to the other side. Conclusions. These results not only show that head-tilt–dependent changes in vertical deviation are not necessarily pathognomonic for SOP, but also, and more importantly, suggest mechanisms that can mimic SOP and suggest a possible role for vertical vergence training in reducing deviations and thus the amount of head tilt required for fusion. Ultimately, vertical vergence training may provide an adjunct or alternative to extraocular muscle surgery in selected cases. PMID:23572100

  11. Long-term evolution of anthropogenic heat fluxes into a subsurface urban heat island.

    PubMed

    Menberg, Kathrin; Blum, Philipp; Schaffitel, Axel; Bayer, Peter

    2013-09-01

    Anthropogenic alterations in urban areas influence the thermal environment causing elevated atmospheric and subsurface temperatures. The subsurface urban heat island effect is observed in several cities. Often shallow urban aquifers exist with thermal anomalies that spread laterally and vertically, resulting in the long-term accumulation of heat. In this study, we develop an analytical heat flux model to investigate possible drivers such as increased ground surface temperatures (GSTs) at artificial surfaces and heat losses from basements of buildings, sewage systems, subsurface district heating networks, and reinjection of thermal wastewater. By modeling the anthropogenic heat flux into the subsurface of the city of Karlsruhe, Germany, in 1977 and 2011, we evaluate long-term trends in the heat flux processes. It revealed that elevated GST and heat loss from basements are dominant factors in the heat anomalies. The average total urban heat flux into the shallow aquifer in Karlsruhe was found to be ?759 ± 89 mW/m(2) in 1977 and 828 ± 143 mW/m(2) in 2011, which represents an annual energy gain of around 1.0 × 10(15) J. However, the amount of thermal energy originating from the individual heat flux processes has changed significantly over the past three decades. PMID:23895264

  12. CIRSS vertical data integration, San Bernardino study

    NASA Technical Reports Server (NTRS)

    Hodson, W.; Christenson, J.; Michel, R. (principal investigators)

    1982-01-01

    The creation and use of a vertically integrated data base, including LANDSAT data, for local planning purposes in a portion of San Bernardino County, California are described. The project illustrates that a vertically integrated approach can benefit local users, can be used to identify and rectify discrepancies in various data sources, and that the LANDSAT component can be effectively used to identify change, perform initial capability/suitability modeling, update existing data, and refine existing data in a geographic information system. Local analyses were developed which produced data of value to planners in the San Bernardino County Planning Department and the San Bernardino National Forest staff.

  13. Sediment Vertical Flux in Unsteady Sheet Flows

    NASA Astrophysics Data System (ADS)

    Hsu, T.; Jenkins, J. T.; Liu, P. L.

    2002-12-01

    In models for sediment suspension, two different boundary conditions have been employed at the sediment bed. Either the sediment concentration is given or the vertical flux of sediment is specified. The specification of the latter is usually called the pick-up function. Recently, several developments towards a better understanding of the sediment bed boundary condition have been reported. Nielson et al (Coastal Engineering 2002, 45, p61-68) have indicated a better performance using the sediment vertical flux as the bed boundary condition in comparisons with experimental data. Also, Drake and Calantoni (Journal of Geophysical Research 2001, 106, C9, p19859-19868) have suggested that in the nearshore environment with its various unsteady flow conditions, the appropriate sediment boundary conditions of a large-scale morphology model must consider both the magnitude the free stream velocity and the acceleration of the flow. In this research, a small-scale sheet flow model based on the two-phase theory is implemented to further study these issues. Averaged two-phase continuum equations are presented for concentrated flows of sediment that are driven by strong, fully developed, unsteady turbulent shear flows over a mobile bed. The particle inter-granular stress is modeled using collisional granular flow theory and a two-equation closure for the fluid turbulence is adopted. In the context of the two-phase theory, sediment is transported through the sediment vertical velocity. Using the fully developed sediment phase continuity equation, it can be shown that the vertical velocity of the sediment must vanish when the flow reaches a steady state. In other words, in fully developed conditions, it is the unsteadiness of the flow that induces the vertical motion of the sediment and that changes the sediment concentration profile. Therefore, implementing a boundary condition based on sediment vertical flux is consistent with both the two-phase theory and with the observation that the flow acceleration is an important parameter. In this paper, the vertical flux of sediment is studied under various combinations of free stream velocity, acceleration, and sediment material properties using the two-phase sheet flow model. Some interesting features of sediment dynamics within the sheet, such as time history of sediment vertical velocity, collisional and turbulent suspension mechanisms are presented.

  14. Concepts for generating optimum vertical flight profiles

    NASA Technical Reports Server (NTRS)

    Sorensen, J. A.

    1979-01-01

    Algorithms for generating optimum vertical profiles are derived and examined. These algorithms form the basis for the design of onboard flight management concepts. The variations in the optimum vertical profiles (resulting from these concepts) due to variations in wind, takeoff weight, and range-to-destination are presented. Further considerations for mechanizing two different onboard methods of computing near-optimum flight profiles are then outlined. Finally, the results are summarized, and recommendations are made for further work. Technical details of optimum trajectory design, steering requirements for following these trajectories, and off-line computer programs for testing the concepts are included.

  15. Geysering inhibitor for vertical cryogenic transfer piping

    NASA Technical Reports Server (NTRS)

    Howard, F. S.

    1973-01-01

    Geysering (i.e., the expulsion of boiling liquid and its vapor from a vertical tube) has been a problem for the missile industry in long vertical cryogenic propellant feed lines connecting the launch vehicle propellant tank with the rocket engines. A proposed novel method of inhibiting geysering and the associated pressure gradients provides a self-starting self-regulating action that is not dependent on other active systems or components. The inhibiting action is attained by incorporating a concentric tube within the main transfer tube to prevent constriction of natural convective flow.

  16. Photochemistry and vertical mixing. [in Uranus atmosphere

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Sandel, B. R.; Romani, P. N.

    1991-01-01

    Earth-based observations relevant to the question of photochemistry and vertical mixing are discussed. Phytolysis of methane, the only known photochemically active volatile in the Uranian atmosphere, produces heavier hydrocarbons, the most abundant of which are ethane, acetylene, and the polyacetylenes. Unlike Jupiter and Saturn, these hydrocarbon products condense at the low temperatures prevalent in the middle atmosphere. Contrary to the pre-Voyager notion that the atmosphere of Uranus is remarkable clear, it is found that the aerosols are widely and extensively distributed. Despite its photodestruction, methane remains stable in the Uranian atmosphere. The vertical mixing on Uranus is found to be the least efficient of any of the planetary atmospheres.

  17. Hypersonic shock tunnel heat transfer tests of the Space Shuttle SILTS pod configuration

    NASA Technical Reports Server (NTRS)

    Wittliff, C. E.

    1983-01-01

    Heat transfer measurements have been made on a 0.0175-scale NASA Space Shuttle orbiter model having a simulated SILTS (Shuttle Infrared Leeside Temperature Sensor) pod on top of the vertical tail. Heat transfer distributions were measured both on the pod and on the vertical tail. The test program covered Mach numbers of 8, 11 and 16 in air, at Reynolds numbers from 100,000 to 18 million, based on model length. The angle of attack ranged from 30 deg to 40 deg at sideslip angles from -2 to +2 deg. Data were obtained with 92 thin film assistance thermometers located on the SILTS pod and on the upper 30 percent of the vertical tail. Heat transfer rates measured on the vertical tail show good agreement with flight data obtained from missions STS-1, -2 and -3. The variation of heat transfer to the pod with Reynolds number, Mach number and angle of attack is discussed.

  18. Enhanced photothermal conversion in vertically oriented gallium arsenide nanowire arrays.

    PubMed

    Walia, Jaspreet; Dhindsa, Navneet; Flannery, Jeremy; Khodabad, Iman; Forrest, James; LaPierre, Ray; Saini, Simarjeet S

    2014-10-01

    The photothermal properties of vertically etched gallium arsenide nanowire arrays are examined using Raman spectroscopy. The nanowires are arranged in square lattices with a constant pitch of 400 nm and diameters ranging from 50 to 155 nm. The arrays were illuminated using a 532 nm laser with an incident energy density of 10 W/mm(2). Nanowire temperatures were highly dependent on the nanowire diameter and were determined by measuring the spectral red-shift for both TO and LO phonons. The highest temperatures were observed for 95 nm diameter nanowires, whose top facets and sidewalls heated up to 600 and 440 K, respectively, and decreased significantly for the smaller or larger diameters studied. The diameter-dependent heating is explained by resonant coupling of the incident laser light into optical modes of the nanowires, resulting in increased absorption. Photothermal activity in a given nanowire diameter can be optimized by proper wavelength selection, as confirmed using computer simulations. This demonstrates that the photothermal properties of GaAs nanowires can be enhanced and tuned by using a photonic lattice structure and that smaller nanowire diameters are not necessarily better to achieve efficient photothermal conversion. The diameter and wavelength dependence of the optical coupling could allow for localized temperature gradients by creating arrays which consist of different diameters. PMID:25233265

  19. Entirely passive heat-pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, D.R.

    1981-02-11

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  20. Computation of vertical profiles of longwave radiative cooling over the equatorial Pacific

    NASA Technical Reports Server (NTRS)

    Ramsey, Perry G.; Vincent, Dayton G.

    1995-01-01

    An important quantity whose magnitude has not been throughly examined is the vertical distribution of heating in the Tropics. The details of the vertical distribution of heating have a significant impact on a number of phenomena, including the 30-60 day oscillation, sometimes known as the intraseasonal oscillation. Prior attempts to establish the structure of the heating relied on limited field data or assimilated data, coupled with climatological radiative heating parameters. The availability of high quality global-scale datasets has made it possible to make more accurate calculations than were possible a few years ago. An important component of the apparent heat budget is the longwave radiative cooling, which in this paper is found by using the ECMWF/WCRP/TOGA Archive 2 and ISCCP C1 datasets, together with a well-established parameterization scheme. A method is developed that can be used to estimate the vertical structure of cloud amounts based on top-of-atmosphere cloud observations, and the results are used with a wide-band longwave parameterization to produce longwave cooling rates over the tropical Pacific Ocean. Outgoing longwave radiation is calculated and compared the ERBE results. The calculated values are generally higher than those from ERBE, though the spatial distributions are similar. Some significant problems exist with the ECMWF upper-tropospheric water vapor amounts, which could imply uncertainties of 0.5 C/day in the calculated cooling rates. This is comparable to the differences associated with the minimum or random overlap assumptions used to generate cloud profiles.

  1. Flash Heating

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2000-03-01

    Meteorites contain millimeter-sized objects called chondrules. They were melted in the solar nebula, the cloud of gas and dust in which the Sun and planets formed. Numerous experiments on rock powders have been done to understand the melting process and the cooling rates chondrules experienced. Most meteorite specialists believe that chondrules formed by flash heating, with almost instantaneous melting, though the length of time they remained molten is uncertain. Can conventional laboratory furnaces heat rock powders rapidly enough to flash melt them? Susan Maharaj and Roger Hewins (Rutgers University, New Brunswick) tested this idea by inserting tiny wires of pure elements (which have precise melting temperatures) into compressed rock powders about 3.5 mm in diameter, and placing the samples into a furnace heated to a range of temperatures. They found that at 1600 C, a sample took only six seconds to reach 1538 C. When placed into a furnace at 1500 C, samples took ten seconds to reach 1495 C. This shows that the flash heating process can be studied in conventional laboratory furnaces.

  2. Vertical root fractures and their management

    PubMed Central

    Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

    2014-01-01

    Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

  3. Vertically aligned biaxially textured molybdenum thin films

    SciTech Connect

    Krishnan, Rahul [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Riley, Michael [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lee, Sabrina [US Army Armament Research, Development and Engineering Center, Benet Labs, Watervliet, New York 12189 (United States); Lu, Toh-Ming [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2011-09-15

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

  4. Twins Vertices in Hypergraphs Raoul Medina1

    E-print Network

    Boyer, Edmond

    Twins Vertices in Hypergraphs Raoul Medina1 and Caroline Noyer and Olivier Raynaud2 Research Report LIMOS/RR-06-07 24 juillet 2006 1 medina@isima.fr 2 raynaud@isima.fr hal-00678051,version1-12Mar2012 #12

  5. Performance evaluation of Vertical Handoff Algorithms

    Microsoft Academic Search

    Alexander Garcia Dávalos; Lina Escobar; Andres Navarro; Adriana Arteaga; Fabio Guerrero; Carlos Salazar

    2010-01-01

    Different Vertical Handoff Algorithms (VHA) have been proposed in the literature recently. However, there is no consensus on how to evaluate performance of different VHA at the research community. Although some models have been proposed for evaluation of the VHA, this issue is a challenge because the VHA have evolved to become more sophisticated, thus the evaluation models must consider

  6. Experimental Research on Vertical Axis Wind Turbine

    Microsoft Academic Search

    Guoying Feng; Zhizhang Liu; Bao Daorina; Zheng Gong

    2009-01-01

    In China, researches on vertical axis wind turbine focus on aerodynamic design mostly. This paper presents the wind tunnel test data of a Darrieus wind turbine. The output powers of wind turbine systems with and without optimal power controller are tested separately. The factors influencing the output power of the wind turbine are analyzed and design methods for wind turbine

  7. Hinged-Blade, Vertical-Shaft Windmill

    NASA Technical Reports Server (NTRS)

    Shultz, B., Jr.

    1985-01-01

    Vertical-shaft windmill concept calls for hinged, flapping blades to increase energy-conversion efficiency by reducing wind-energy loss. Hinged Blade Halves unfold to catch wind when moving with it, then fold away from wind when moving against it.

  8. Radar For Measuring Vertical Cloud Structure

    NASA Technical Reports Server (NTRS)

    Im, Eastwood; Li, Fuk K.; Durden, Stephen L.; Wilson, William J.

    1995-01-01

    Proposed radar system views clouds from above and measures their vertical structures with resolution of 500 m. Two versions of system; initial developmental version to be flown aboard aircraft and final version flown aboard spacecraft in circular orbit around Earth at altitude of 400 km.

  9. A theoretical analysis of vertical flow equilibrium

    Microsoft Academic Search

    Y. C. Yortsos

    1995-01-01

    The assumption of Vertical Equilibrium (VE) and of parallel flow conditions, in general, is often applied to the modeling of flow and displacement in natural porous media. However, the methodology for the development of the various models is rather intuitive, and no rigorous method is currently available. In this paper, we develop an asymptotic theory using as parameter the variable

  10. Vertical Fracture Containment During Massive Hydraulic Fracturing

    Microsoft Academic Search

    D. E. Cormack; R. L. Fung; S. Vijayakumar

    1983-01-01

    Massive hydraulic fractures are projected to play a major role in the recovery of the tremendous reserves of gas tied up in the tight gas sands of the Deep Basin of N. Alberta and British Columbia. One of the major problems in designing fractures in such formations is the uncertain vertical extent of these fractures: fracture containment. This work presents

  11. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    ERIC Educational Resources Information Center

    Carter, J. B.; And Others

    1983-01-01

    Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

  12. Vertical Jump: Biomechanical Analysis and Simulation Study

    E-print Network

    Babic, Jan

    are energy inefficient. With the understanding of the anatomy and the biomechanics of the human body, one can find out that, beside the shape, majority of today's humanoid robots and human bodies do not have a lot31 Vertical Jump: Biomechanical Analysis and Simulation Study Jan Babi and Jadran Lenar i "Jozef

  13. Dynamic crosswind fatigue of slender vertical structures

    Microsoft Academic Search

    Maria Pia Repetto; Giovanni Solari

    2002-01-01

    Wind-excited vibrations of slender structures can induce fatigue damage and cause structural failure without exceeding ultimate limit state. Unfortunately, the growing importance of this problem is coupled with an evident lack of simple calculation criteria. This paper proposes a mathematical method for evaluating the crosswind fatigue of slender vertical structures, which represents the dual formulation of a parallel method that

  14. Introduction Diel vertical migration occurs when plankton

    E-print Network

    New Hampshire, University of

    over a 24 h cycle. Zooplankton typically migrate nocturnally, occupying depths near the hypolimnion and can occur among both marine and freshwater plankton (Lampert & Sommer 1997). Although there have been many studies on zooplankton DVM, little is known about the daily vertical movements of phytoplank- ton

  15. Darrieus vertical axis wind turbine program overview

    Microsoft Academic Search

    R. H. Braasch

    1979-01-01

    Some of the more salient recent developments in the Darrieus vertical axis wind turbine technology are presented. First generation costs and future plans are discussed. Potential design improvements are presented along with their cost benefits. Aerodynamic structural, and system analyses capabilities were developed to support and evaluate the system design.

  16. Darrieus vertical axis wind turbine program overview

    Microsoft Academic Search

    Braasch

    2008-01-01

    As a US Department of Energy (DOE) laboratory, Sandia Laboratories is developing Darrieus vertical axis wind turbine (VAWT) technology with the objective of encouraging private industry to produce economically feasible, commercially marketable wind energy systems. The first full cycle of development is essentially complete, and resulting current technology designs have been evaluated for cost-effectiveness. Aerodynamic, structural, and system analyses capabilities

  17. Vertical distribution of natural radionuclides in soils

    NASA Astrophysics Data System (ADS)

    Blanco Rodríguez, P.; Tomé, F. Vera; Lozano, J. C.

    2012-04-01

    Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation counters (LKB Quantulus 1220™) were used in order to determine the activity concentration of 238U, 232Th, 234U, 230Th, 226Ra, and 210Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were selected with different levels of influence from the installation, in such a way that they had different levels of radioactive contamination. The vertical profiles in the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. The possible contamination of subsurface waters depends strongly on vertical migration, and the transfer to plants (herbs, shrubs, and trees) also will depend on the distribution of the radionuclides in the root zone. The study of the activity ratios between radionuclides belonging to the same series allowed us to assess the differing behaviour of the radionuclides involved. The vertical profiles for these radionuclides were different at each sampling point, showing the local impact of the installation. However, the profiles per point were similar for the long-lived radionuclides of the 238TJ series (238U, 234U, 230Th, and 226Ra). Also, a major disequilibrium was observed between 210Pb and 226Ra in the surface layer, due to 222Rn emanation and subsequent surface deposition of 210Pb.

  18. VERTICAL PRODUCT INNOVATION AND PARALLEL IMPORTS

    Microsoft Academic Search

    CHANGYING LI

    2005-01-01

    In this paper, we develop a model of endogenous R&D in vertical product innovation by an original manufacturer facing Bertrand competition from parallel importer(s). We show that if parallel imports are prohibited among the distributors' countries and there is at least one country other than the manufacturer's homeland in which there is only one distributor, then allowing reimports reduces the

  19. Silicon Vertically Integrated Nanowire Field Effect Transistors

    E-print Network

    Yang, Peidong

    Silicon Vertically Integrated Nanowire Field Effect Transistors Josh Goldberger, Allon I. Hochbaum Manuscript Received February 24, 2006 ABSTRACT Silicon nanowires have received considerable attention, alternative transistor geometries need to be considered.1 Silicon nanowire based devices2,3 and horizontal

  20. Vertical distribution of Titan's atmospheric neutral constituents

    Microsoft Academic Search

    L. M. Lara; E. Lellouch; J. J. López-Moreno; R. Rodrigo

    1996-01-01

    The vertical distribution of Titan's neutral atmosphere compounds is calculated from a new photochemical model extending from 40 to 1432 km. This model makes use of many updated reaction rates, and of the new scheme for methane photolysis proposed by Mordaunt et al. [1993]. The model also includes a realistic treatment of the dissociation of N2, of the deposition of

  1. Kinematic Features of Unrestrained Vertical Arm Movements

    Microsoft Academic Search

    CHRISTOPHER G. ATKESON; JOHN M. HOLLERBACH

    1985-01-01

    Unrestrained human arm trajectories between point targets have been investigated using a three-dimensional tracking apparatus, the Selspot system. Movements were executed between different points in a vertical plane under varying conditions of speed and hand-held load. In contrast to past results which emphasized the straightness of hand paths, movement regions were discovered in which the hand paths were curved. All

  2. Vertical occupational mobility and its measurement

    Microsoft Academic Search

    Shirley Dex; Joanne Lindley; Kelly Ward

    2007-01-01

    This paper describes a number of alternative approaches to devising a vertical occupational scale and compares the outcomes of different scales on calculations of occupational mobility. The paper describes the conceptual issues relevant to calculating occupational mobility and documents the measurement error embedded in the choice of measure, as applied to different data sets. The ranking schemes used include SOC

  3. [Vertical and tortional deviations in early strabismus].

    PubMed

    Spielmann, A

    1990-04-01

    The occlusion of one eye may trigger two types of deviation: 1) Heterophorias: the occluded eye deviates towards a horizontal, vertical or torsional abnormal position of rest. Fusion keeps the eyes straight during binocular fixation. 2) Dissociated deviations, horizontal (DHD), vertical (DVD), torsional (DTD): they are found in infantile strabismus. The deviation without fixation is always smaller than the deviation of the occluded eye. The more typical cases are the ones where the position of rest without fixation is an orthoposition. Normal binocular vision is lacking. Most of the time, an alternant neutralisation is found: the occlusion deviation is not the return of the occluded eye to an abnormal position of rest. The deviation is caused by a disequilibrium of binocular retinal stimulations. Horizontal and vertical deviations are easy to study. It is not the case in dissociated torsional deviation (DTD) where the incyclotorsion does not exist when fixation is absent. An indirect proof of extorsion is given by the study of horizontal and vertical deviations determined in the cardinal position of gaze. Extorsion of the globus leeds always to abnormal actions of the recti. This give a typical synoptometer chart which is found in any extorsion whatever its origins: paralysis, alphabetic patterns or infantile strabismus. Dissociated extorsions are always associated with a bilateral elevation in the primary position. Dissociated deviations are found in infantile strabismus with the other dissociations phenomenon such as nystagmus, optokinetic nystagmus asymmetry, fixation in adduction preference (and incyclotorsion). PMID:2208493

  4. Vertical technology transfer via international outsourcing

    Microsoft Academic Search

    Howard Pack; Kamal Saggi

    2001-01-01

    To analyze the effect of vertical technology transfer on industrial development in lesser developed countries (LDCs), we develop a model in which the technology transferred to an LDC supplier by a developed country (DC) importer can diffuse to other LDC firms. Surprisingly, even if such diffusion in the LDC market leads to entry into the DC market, it can benefit

  5. Food Supply Chains with Vertical Integration

    E-print Network

    Nagurney, Anna

    Food Supply Chains with Vertical Integration SOM 822 Research Paper Diogo Souza-Monteiro Dep. of Resource Economics 05/10/2004 #12;Introduction Food Supply chains are becoming increasingly complex in different tiers of food chains. Barkena and Drabenstott (1995) claim that contracts are quickly taking

  6. Heat transfer coefficients of dilute flowing gas-solids suspensions

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Heat transfer coefficients of air-glass, argon-glass, and argon-aluminum suspensions were measured in horizontal and vertical tubes. The glass, 21.6 and 36.0 micron diameter particles, was suspended at gas Reynolds numbers between 11,000 and 21,000 and loading ratios between 0 and 2.5. The presence of particles generally reduced the heat transfer coefficient. The circulation of aluminum powder in the 0.870 inch diameter closed loop system produced tenacious deposits on protuberances into the stream. In the vertical test section, the Nusselt number reduction was attributed to viscous sublayer thickening; in the horizontal test section to particle deposition.

  7. Vertical Acoustic Arrays in the Deep Ocean

    NASA Astrophysics Data System (ADS)

    Fisher, F.

    2002-12-01

    The R/P FLIP has made possible the deployments of vertical arrays to study sound propagation and ambient noise in the deep ocean in ways never before possible from existing research vessels. Long vertical arrays can be deployed without the flow noise contamination from platform motion, long a bane for making such studies. The vertical stability of FLIP combined with the deep mooring capability developed by Earl D. Bronson made it possible to deploy multi-element arrays beginning with a versatile 20 element array with variable spacing developed by Bill Whitney in Fred Spiess's group. The 20 element array consisted of bungee mounted hydrophones in metal cages at either uniform spacing or variable spacing to meet directivity or other requirements. It was assembled on station in the vertical and deployed to the desired depths for the elements. Gerald Morris at MPL conducted ambient noise studies using variable spacing of the elements to below the critical depth as well as in the water column above. Vic Anderson used it for his DIMUS processing system for detecting low level signals masked by ambient noise. As a 500 meter array, I used it for a series of CONTRACK (Continuous Tracking of signals at long range) experiments to resolve multipaths so they wouldn't interfere with one another. The VEKA vertical array developed by Rick Swenson of NORDA was deployed in very deep (below 3300 m) water by Dan Ramsdale of NORDA using the winch and double lay armored cable on FLIP, the same cable system for the MPL 20 element array. In my group Bruce Williams designed a rapidly deployable array to study vertical anisotropy of ambient noise as a function of range from near shore shipping via downslope conversion in a series of 48 hours FLIP stations 350, 1000 and 1500 miles from the Pacific coast. A short 120 element array, 1000 meters long, was built by John Hildebrands's group for a test of matched field processing and the SLICE experiment in acoustic tomography research of Peter Worcester and Walter Munk in 1987. Later a different 200 element array over 3000 meters long was also built by John Hildebrand's group for deloyment in the VAST experiment in 1987. This array included acoustic navigation to measure element location for several different experiments including matched field processing at 1000 km, normal mode studies and down-slope conversion of shipping noise and by Stan Flatte of UCSC for looking at long range barotropic wave reflections from Alaska. In a separate talk, Gerald D'Spain will discuss a trifar (3D) vertical array developed at MPL.

  8. Strategic optimization of large-scale vertical closed-loop shallow geothermal systems

    NASA Astrophysics Data System (ADS)

    Hecht-Méndez, J.; de Paly, M.; Beck, M.; Blum, P.; Bayer, P.

    2012-04-01

    Vertical closed-loop geothermal systems or ground source heat pump (GSHP) systems with multiple vertical borehole heat exchangers (BHEs) are attractive technologies that provide heating and cooling to large facilities such as hotels, schools, big office buildings or district heating systems. Currently, the worldwide number of installed systems shows a recurrent increase. By running arrays of multiple BHEs, the energy demand of a given facility is fulfilled by exchanging heat with the ground. Due to practical and technical reasons, square arrays of the BHEs are commonly used and the total energy extraction from the subsurface is accomplished by an equal operation of each BHE. Moreover, standard designing practices disregard the presence of groundwater flow. We present a simulation-optimization approach that is able to regulate the individual operation of multiple BHEs, depending on the given hydro-geothermal conditions. The developed approach optimizes the overall performance of the geothermal system while mitigating the environmental impact. As an example, a synthetic case with a geothermal system using 25 BHEs for supplying a seasonal heating energy demand is defined. The optimization approach is evaluated for finding optimal energy extractions for 15 scenarios with different specific constant groundwater flow velocities. Ground temperature development is simulated using the optimal energy extractions and contrasted against standard application. It is demonstrated that optimized systems always level the ground temperature distribution and generate smaller subsurface temperature changes than non-optimized ones. Mean underground temperature changes within the studied BHE field are between 13% and 24% smaller when the optimized system is used. By applying the optimized energy extraction patterns, the temperature of the heat carrier fluid in the BHE, which controls the overall performance of the system, can also be raised by more than 1 °C.

  9. Forced flow boiling heat transfer of liquid hydrogen for superconductor cooling

    Microsoft Academic Search

    Yasuyuki Shirai; Hideki Tatsumoto; Masahiro Shiotsu; Koichi Hata; Hiroaki Kobayashi; Yoshihiro Naruo; Yoshifumi Inatani; Katsuhiro Kinoshita

    2011-01-01

    Heat transfer from inner side of a heated vertical pipe to liquid hydrogen flowing upward was first measured at the pressure of 0.7MPa for wide ranges of flow rates and liquid temperatures. The heat transfer coefficients in non-boiling regime for each flow velocity were well in agreement with the Dittus–Boelter equation. The heat fluxes at the inception of boiling and

  10. Geothermal direct-heat utilization assistance. Quarterly project progress report, July 1994--September 1994

    SciTech Connect

    Not Available

    1994-10-01

    This paper is a third quarter 1994 report of activities of the Geo-Heat Center of Oregon Institute of Technology. It describes contacts with parties during this period related to assistance with geothermal direct heat applications. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, resources, and equipment. Research is also being conducted on failures of vertical lineshaft turbines in geothermal wells.

  11. Conduct a state-of-the-art survey of existing knowledge for the design of ground-source heat pumps

    NASA Astrophysics Data System (ADS)

    Ball, D. A.

    1982-03-01

    Horizontal serpentine coils have been and are at present the most common coil configuration. Best design data exist for horizontal coils in heating only applications with moist soil. Applications in dry soil or where significant summer cooling is required are not as well understood at this time. A seasonal performance factor of about 3.0 can be expected for a properly designed and installed residential ground-coupled heat-pump system. Long-term durability of buried steel and cooper tubing has been demonstrated. Life expectancy of thin-walled polyethylene tubing in the heating-only application is expected to be equally as good: however, present experience is limited to less than five years. In the cooling application with heat-rejection temperatures exceeding 100 F, some cracking has been experienced upon subsequent cool-down for heating operation due to localized stresses induced by conformity of the tubing to bedding material (stones) when hot. Receding of the soil from the pipe after a period of several years was experienced in the late 1940's. An understanding of this phenomenon may be crucial to the long-term operating success of these systems.

  12. Geothermal district heating systems

    NASA Astrophysics Data System (ADS)

    Budney, G. S.; Childs, F.

    1982-06-01

    Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

  13. Waste heat recovery using heat pipe heat exchanger for heating automobile using exhaust gas

    Microsoft Academic Search

    Feng Yang; Xiugan Yuan; Guiping Lin

    2003-01-01

    The feasibility of using heat pipe heat exchangers for heating applying automotive exhaust gas is studied and the calculation method is developed. Practical heat pipe heat exchanger is set up for heating HS663, a large bus. Simple experiments are carried out to examine the performance of the heat exchanger. It is shown that the experimental results, which indicate the benefit

  14. Emerging heat pipe applications

    Microsoft Academic Search

    A. Basuilis; D. J. Formiller

    1978-01-01

    The article discusses the application of heat pipes in various industrial, military, and space projects. Several types of heat pipes are described, including simple cylindrical heat pipes, switching heat pipes, thermal diodes, variable conductance heat pipes, and vapor chambers. Potential future applications of heat pipes are identified in the fields of electronics, spacecraft thermal control, heat pipe recovery systems, and

  15. The cloud radiative heating over the Indian subcontinent

    NASA Astrophysics Data System (ADS)

    Johansson, Erik; Devasthale, Abhay; Tollstadius, Caroline; Ekman, Annica; L'Ecuyer, Tristan

    2013-04-01

    Monsoonal circulation is one of dominant modes of seasonal variability that affects the livelihood of millions over the Indian subcontinent. It is therefore important to understand various processes influencing monsoon, especially those dealing with atmospheric interactions. Convective cloud systems cover much of the subcontinent during the summer season and these systems occur in a wide range of spatio-temporal scales ranging from individual convective towers with the lifetime of some hours to mesoscale systems covering hundreds of kilometers and sustaining for days. The importance of diabatic heating of the atmosphere produced by these systems during monsoon is pointed out in a number of studies, including the role of cloud radiative heating. However, very little is known regarding the vertical structure of cloud radiative heating and its pre- to post-monsoon transitioning. In this context, using state-of-the-art satellite based estimates of cloud radiative heating from CloudSat (five year period) and TRMM (nine year period), we try to address the following scientific questions in the present study. 1) How does the vertical structure of cloud radiative heating change from pre-monsoon to post-monsoon season? 2) How do intraseasonal oscillations in monsoonal rainfall influence variability in the heat budget? 3) How do the zonal and meridional vertical heating gradients change during monsoon months?

  16. Performance of various RANS eddy-viscosity models for turbulent natural convection in tall vertical cavities

    NASA Astrophysics Data System (ADS)

    El Moutaouakil, L.; Zrikem, Z.; Abdelbaki, A.

    2014-08-01

    The present study is dedicated to the identification of turbulence models that are accurate and numerically economic for computing the natural air-flow and heat transfer by convection in tall cavities with differentially heated vertical walls. The eddy-viscosity models (EVM) are among the simplest to implement and the most economical to treat this problem. This study evaluated the dynamic, thermal and computational performances of twenty EVM turbulence models with one, two or three-equation closure. All the models were first implemented in several in-house codes using the finite volume method. The predictions of the retained models in terms of profiles of velocity, temperature and vertical velocity fluctuations in the cavity have been compared with those of experimental or numerical studies. The obtained results were used to identify the turbulence models that are accurate and numerically economic in predicting natural convection in vertical cavities with a high aspect ratio. The EVM models with three-equation (v2-f and ?-f) provide the most accurate mean and fluctuating quantities, followed by the k-? RNG (ReNormalization Group) and k-? SST (Shear Stress Transport) models. The computing time of these four models is higher than that of the 2L (two-layer) and q-? models, which provide fairly accurate results especially for the mean heat transfer between the vertical active walls. The other one-equation (Spalart and Allmaras model) and two-equation (k-?, k-? and hybrid models) turbulence models tested in this work, have a high computing time and/or predictions that are not sufficiently precise simultaneously for both velocity and temperature fields.

  17. Ceramic heat pipe heat exchangers

    Microsoft Academic Search

    W. A. Ranken

    1976-01-01

    High-temperature strength, resistance to corrosive atmospheres, and moderate cost combine to make ceramic materials an obvious choice for construction of high-temperature thermal energy recuperator systems. Despite these advantages, ceramic recuperators are steadily being replaced by metallic units at considerable sacrifice in maximum air or fuel preheat temperatures and hence in recovery efficiency. By constructing a recuperator from ceramic heat pipes,

  18. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, E. A.; Adler, R.; Haddad, Z.; Hou, A.; Iguchi, T.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.

    2004-01-01

    Rainfall production is the fundamental variable within the Earth's hydrological cycle because it is both the principal forcing term in surface water budgets and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the tropics - as well as modifying the energetic efficiencies of midlatitude weather systems. This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global tropics and sub-tropics, information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. The paper examines how the observed TRMM distribution of rainfall has advanced an understanding of the global water and energy cycle and its consequent relationship to the atmospheric general circulation and climate via latent heat release. A set of algorithm methodologies that are being used to estimate latent heating based on rain rate retrievals from the TRMM observations are described. The characteristics of these algorithms and the latent heating products that can be generated from them are also described, along with validation analyses of the heating products themselves. Finally, the investigation provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  19. The effect of sediment thermal conductivity on vertical groundwater flux estimates

    NASA Astrophysics Data System (ADS)

    Sebok, Eva; Müller, Sascha; Engesgaard, Peter; Duque, Carlos

    2015-04-01

    The interaction between groundwater and surface water is of great importance both from ecological and water management perspective. The exchange fluxes are often estimated based on vertical temperature profiles taken from shallow sediments assuming a homogeneous standard value of sediment thermal conductivity. Here we report on a field investigation in a stream and in a fjord, where vertical profiles of sediment thermal conductivity and temperatures were measured in order to, (i) define the vertical variability in sediment thermal conductivity, (ii) quantify the effect of heterogeneity in sediment thermal conductivity on the estimated vertical groundwater fluxes. The study was carried out at field sites located in Ringkøbing fjord and Holtum stream in Western Denmark. Both locations have soft, sandy sediments with an upper organic layer at the fjord site. First 9 and 12 vertical sediment temperature profiles up to 0.5 m depth below the sediment bed were collected in the fjord and in the stream, respectively. Later sediment cores of 0.05 m diameter were removed at the location of the temperature profiles. Sediment thermal conductivity was measured in the sediment cores at 0.1 m intervals with a Decagon KD2 Pro device. A 1D flow and heat transport model (HydroGeoSphere) was set up and vertical groundwater fluxes were estimated based on the measured vertical sediment temperature profiles by coupling the model with PEST. To determine the effect of heterogeneity in sediment thermal conductivity on estimated vertical groundwater fluxes, the model was run by assigning (i) a homogeneous thermal conductivity for all sediment layers, calculated as the average sediment thermal conductivity of the profile, (ii) measured sediment thermal conductivities to the different model layers. The field survey showed that sediment thermal conductivity over a 0.5 m profile below the sediment bed is not uniform, having the largest variability in the fjord where organic sediments were also present. Using the measured sediment thermal conductivity for the different model layers instead of a homogeneous distribution did not result in a better fit between observed and simulated sediment temperature profiles. The estimated groundwater fluxes however were greatly affected by using the measured thermal conductivities resulting in changes of ± 45% in estimated vertical fluxes.

  20. The vertical-mill stage : design of a vertical movement stage for surface machining

    E-print Network

    Herrera, Juan, Jr

    2007-01-01

    To allow the widespread use of three dimensional patterns on walls, the manufacturing cost must be reduced. The goal of this project is to design a machine for vertical axis movement which can be measured and controlled. ...