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1

Theoretical and experimental analysis of vertical, concentric-tube ground-coupled heat exchangers  

Microsoft Academic Search

An experimental and analytical project to study the design of vertical, concentric-tube ground-coupled heat exchangers for use in heat pump applications is described. A mathematical model was developed and converted into a computer program to simulate the operation of the ground-coupled heat exchanger. The experimental apparatus consisted of a concentric configuration of two 47.2-m (155-ft) polyvinyl chloride (PVC) pipes (sealed

V. C. Mei; S. K. Fischer

1984-01-01

2

An experimental study of heating performance and seasonal modeling of vertical U-tube ground coupled heat pumps  

E-print Network

monitoring were provided and no transient analysis was done for heating or cooling. Metz [1983] analyzed a horizontally configured ground coupled unit in Long Island, New York during the winter of 1981-82 and the summer of 1982. He reported only a slight... monitoring were provided and no transient analysis was done for heating or cooling. Metz [1983] analyzed a horizontally configured ground coupled unit in Long Island, New York during the winter of 1981-82 and the summer of 1982. He reported only a slight...

Margo, Randal E.

2012-06-07

3

Cooling performance of a vertical ground-coupled heat pump system installed in a school building  

Microsoft Academic Search

This paper presents the cooling performance of a water-to-refrigerant type ground heat source heat pump system (GSHP) installed in a school building in Korea. The evaluation of the cooling performance has been conducted under the actual operation of GSHP system in the summer of year 2007. Ten heat pump units with the capacity of 10HP each were installed in the

Yujin Hwang; Jae-Keun Lee; Young-Man Jeong; Kyung-Min Koo; Dong-Hyuk Lee; In-Kyu Kim; Sim-Won Jin; Soo H. Kim

2009-01-01

4

Optimized ground coupled heat pump mechanical package  

NASA Astrophysics Data System (ADS)

This project addresses the question of how well a ground coupled heat pump system could perform with a heat pump which was designed specifically for such systems operating in a northern climate. Conventionally, systems are designed around water source heat pumps which are not designed for ground coupled heat pump application. The objective of the project is to minimize the life cycle cost for a ground coupled system given the freedom to design the heat pump and the ground coil in concert. In order to achieve this objective a number of modeling tools were developed which will likely be of interest in their own right.

Catan, M. A.

5

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

Microsoft Academic Search

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

Onder Ozgener; Arif Hepbasli; Leyla Ozgener

2007-01-01

6

The Design of Ground-Coupled Heat Pump Systems  

E-print Network

(ft) r values of lntegral at X = - , 2JZ; see Table 1. coil length, m (ft) heat rate, W/m (Btu/h'ft) temperature at a distance r, OC (F) Mean earth temperature OC (F) normal or undisturbed earth temperature. OC (F) soil thermal ilnductance... dlf f us1 vi t y of so 11. m2/s (it2/&) or m2/day (ft2/day) 0 varlable of integration INTRODWICN AND OVERVIEW THE GROUND COUPLED HEAT PU19 OMU3PT Ground coupled heat pumps are closed-loop systems designed to use the earth as a heat source and...

Parker, J. D.

1985-01-01

7

Ground-Coupled Heat Pump Applications and Case Studies  

E-print Network

APPLICATIONS OF GROUND COUPLED HEAT PUMPS Earth-coupled water-source heat pump systems are ex- pensive ($800 to $1,500 more per ton than conventional sys- tems) because of the large amount of pipe needed for the ground loop. Nevertheless, long life and low... APPLICATIONS OF GROUND COUPLED HEAT PUMPS Earth-coupled water-source heat pump systems are ex- pensive ($800 to $1,500 more per ton than conventional sys- tems) because of the large amount of pipe needed for the ground loop. Nevertheless, long life and low...

Braud, H. J.

1989-01-01

8

Cooperative heat transfer and ground coupled storage system  

DOEpatents

A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.

Metz, Philip D. (Rocky Point, NY)

1982-01-01

9

Cooperative Heat Transfer and Ground Coupled Storage System.  

National Technical Information Service (NTIS)

A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally ma...

P. D. Metz

1979-01-01

10

Optimized ground coupled heat pump mechanical package  

Microsoft Academic Search

The system which was optimized was a horizontal earth coil in a given house in the Pittsburgh area. The types of components used in the heat pump are essentially conventional. The method of this study is derived from one used to optimize an air-source heat pump for operation at standard steady state conditions. A computer model, created at Oak Ridge

Catan

1984-01-01

11

Optimized ground coupled heat pump design: Phase 1, Final report  

Microsoft Academic Search

This report describes the first phase of a project to design a water-to-air heat pump optimized for ground coupling applications. The project is being conducted jointly by Brookhaven National Laboratory (BNL), Oak Ridge National Laboratory (ORNL), and an industrial partner to be selected via a competitive procurement. In the completion of Phase I, three major tasks were completed. First, based

J. W. Andrews; M. Catan; P. Le Doux; P. D. Metz; J. H. Saunders

1985-01-01

12

Performance of a hybrid ground-coupled heat pump system  

SciTech Connect

In climates dominated by air conditioning, a few so-called hybrid ground-coupled heat pump (GCHP) systems have been built. The hybrid system uses both a ground-coupled heat exchanger and a cooling tower, thereby reducing the amount of ground-coupling heat exchanger necessary. Although this concept has been shown to be feasible, the performance of such a system has not been measured in detail. Since it may be possible to achieve significant performance improvements in such systems by modifying the design and operational practices, detailed performance monitoring of such systems is needed. This paper describes a project that has been undertaken to collect performance data from a hybrid GCHP system at Fort Polk, LA. This paper presents performance data for a period of about 22 months, including data from portions of two heating and cooling seasons. The energy input to the GCHPs themselves will be presented, as well as the energy rejected to the ground in the cooling mode and that extracted from the ground in the heating mode. Energy flows in the cooling tower also will be addressed, along with the power consumption of the circulating pumps and the cooling tower.

Phetteplace, G. [Army Cold Regions Research and Engineering Lab., Hanover, NH (United States); Sullivan, W. [Sandia National Lab., Albuquerque, NM (United States)

1998-10-01

13

Study on hybrid ground-coupled heat pump systems  

Microsoft Academic Search

Although ground-coupled heat pump (GCHP) systems are becoming attractive air-conditioning systems in some regions, the significant drawback for their wider application is the high initial cost. Besides, more energy is rejected into ground by the GCHP system installed in cooling-dominated buildings than the energy extracted from ground on an annual basis and this imbalance can result in the degradation of

Man Yi; Yang Hongxing; Fang Zhaohong

2008-01-01

14

An experimental and analytical study of the transient behavior of vertical u-tube ground-coupled heat pumps in the cooling mode  

E-print Network

Vater H aar Voter to centplc T use Heat Exchanger U-Tuse Heat Exchanger Figure 2. 2 ? Schematic Diagrams of Concentric-Tube and U-Tube Heat Exchangers The final classification of ground heat exchangers is based on their flow configuration... Vater H aar Voter to centplc T use Heat Exchanger U-Tuse Heat Exchanger Figure 2. 2 ? Schematic Diagrams of Concentric-Tube and U-Tube Heat Exchangers The final classification of ground heat exchangers is based on their flow configuration...

Dobson, Monte Keith

2012-06-07

15

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

E-print Network

-08-08 concepts of this program can be found in Kavanaugh & Rafferty (1997), The method is based on the solution of the cylindrical source model. This method has been used widely within the United States for design of the GCHP systems (Kavanaugh & Rafferty... verification of vertical ground-coupled heat pump systems. Ph.D. dissertation. Stillwater, OK: Oklahoma State University. Kavanaugh, S., & Rafferty, K. 1997. Ground-source heat pumps, design of geothermal systems for commercial and institutional buildings...

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

16

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

E-print Network

#12;GROUND-COUPLED HEAT-PUMP-SYSTEM EXPERIMENTAL RESULTS* Philip D. Metz _Solar and Renewables of complete ground coupled heat pump systems (4). Experimental results have been compared to GROCS simulation the cost and feasibility of a residential ground coupled heat pump space conditioning system requiring

Oak Ridge National Laboratory

17

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

NASA Astrophysics Data System (ADS)

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.

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

1980-11-01

18

Model for Ground-Coupled Heat and Moisture Transfer from Buildings  

SciTech Connect

An important factor in soil heat transfer that is often over looked is the effect of moisture, which can vary the effective thermal conductivity by a factor of ten. The objective of this research was to investigate the ground-coupled heat and moisture transfer from buildings, and to develop results and tools to improve energy simulation of ground-coupled heat transfer.

Deru, M.

2003-06-01

19

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

NASA Astrophysics Data System (ADS)

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, Texas; and Madison, Wisconsin. 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 Fort Worth. Though the ground-coupled stand-alone heat pump provides 51 percent of the heating and cooling load with non-purchased energy in Fort Worth, its thermal performance in Washington and Madison is poor.

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

1981-07-01

20

The use of ground-coupled tanks in solar-assisted heat-pump systems  

Microsoft Academic Search

A research program at Brookhaven National Laboratory (BNL) has studied ground coupling, i.e., the use of the earth as a heat source\\/sink or storage element, for solar-assisted heat-pump systems. As part of this research program, four buried tank experiments were operated between December 1978 and March 1981 in order to determine the feasibility of ground-coupled tanks in these systems. Heat

P. D. Metz

1982-01-01

21

Ground coupled solar heat pump research program in the United States  

SciTech Connect

The ground coupling research program funded by the Systems Development Division of the Office of Solar Applications of the US Department of Energy studies the use of the earth as a heat source/sink or storage element for solar heat pump space conditioning systems. The goal of this research program is to determine the feasibility of ground coupling, and if feasibility is confirmed, to create handbooks which facilitate widespread application of ground coupling. The research program is outlined and the research projects currently in progress and how they fit into the program are described. Progress toward the program goal is evaluated.

Metz, P D

1980-01-01

22

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

Microsoft Academic Search

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

Hikmet Esen; Mustafa Inalli; Mehmet Esen

2007-01-01

23

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

E-print Network

Short communication Optimization of hybrid ­ ground coupled and air source ­ heat pump systems to water heat pump Thermal storage device Hybrid HVAC system Energy efficiency Numerical simulation a b driven by an air to water heat pump and around the 82% compared with an HVAC system driven by a ground

Fernández de Córdoba, Pedro

24

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

Microsoft Academic Search

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.

Hikmet Esen; Mustafa Inalli; Abdulkadir Sengür; Mehmet Esen

2008-01-01

25

Overview of ground coupled heat pump research and technology transfer activities  

Microsoft Academic Search

Highlights of DOE-sponsored ground coupled heat pump (GCHP) research at Oak Ridge National Laboratory (ORNL) are presented. ORNL, in cooperation with Niagara Mohawk Power Company, Climate Master, Inc., and Brookhaven National Laboratory developed and demonstrated an advanced GCHP design concept with shorter ground coils that can reduce installed costs for northern climates. In these areas it can also enhance the

V. D. Baxter; V. C. Mei

1988-01-01

26

R&D of the ground-coupled heat pump technology in China  

Microsoft Academic Search

The ground-coupled heat pump (GCHP) systems have been identified as one of the best sustainable energy technologies for space\\u000a heating and cooling in residential and commercial buildings. In this paper, research on and development of the GCHP technology\\u000a in China are summarized. New models are presented for efficient thermal analysis of ground heat exchangers, of which one-\\u000a and two-dimensional solid

Nairen Diao; Ping Cui; Junhong Liu; Zhaohong Fang

2010-01-01

27

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

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

Wisconsin at Madison, University of

28

Second generation ground coupled solar assisted heat pump systems. Six month progress report  

SciTech Connect

Progress is reported on an investigation of the technical and commercial viability of a novel ground coupled, solar assisted heat pump system for residential space heating and cooling applications. Specific areas of study are solar collector/heat rejector performance, flat plate earth heat exchanger performance, system performance simulations, and commercialization and marketing analysis. Collector/rejector performance, determined by various thermal experiments, is discussed. The design and construction of an experimental site to study ground coupling is discussed. Theoretical analysis is also presented. The performance of the GCSAHP system and conventional alternatives, as determined by simple computer models, is presented and discussed. Finally, the commercial viability of this unique space conditioning system is examined.

Rhodes, G W; Backlund, J C; Helm, J M

1981-01-01

29

A review for the applications and integrated approaches of ground-coupled heat pump systems  

Microsoft Academic Search

During the past few decades, a large number of ground-coupled heat pump (GCHP) systems have been widely applied in various buildings around the world due to the attractive advantages of high efficiency and environmental friendliness. However, most buildings in warm-climate or cold-climate areas have unbalanced loads, dominated by either cooling loads or heating loads. Therefore, it is necessary to employ

X. Q. Zhai; M. Qu; X. Yu; Y. Yang; R. Z. Wang

2011-01-01

30

Modelling a ground-coupled heat pump system using adaptive neuro-fuzzy inference systems  

Microsoft Academic Search

The aim of this study is to demonstrate the usefulness of an adaptive neuro-fuzzy inference system (ANFIS) for the modelling of ground-coupled heat pump (GCHP) system. The GCHP system connected to a test room with 16.24m2 floor area in F?rat University, Elaz?? (38.41°N, 39.14°E), Turkey, was designed and constructed. The heating and cooling loads of the test room were 2.5

Hikmet Esen; Mustafa Inalli; Abdulkadir Sengur; Mehmet Esen

2008-01-01

31

Comparative evaluation of ground-coupled heat pumps that use solar energy  

NASA Astrophysics Data System (ADS)

A study of combined building space conditioning systems using both solar energy and heat pumps was conducted for the US Department of Energy (DOE). Several of these systems used the ground as a source or storage element for thermal energy, in order to reduce or eliminate the need for backup energy. The results obtained for these systems in the United States are summarized and the relationship of ground-coupling to the overall US solar-assisted heat-pump program is described.

Andrews, J. W.; Catan, M. A.

1985-03-01

32

Artificial neural networks and adaptive neuro-fuzzy assessments for ground-coupled heat pump system  

Microsoft Academic Search

This article present a comparison of artificial neural network (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) applied for modelling a ground-coupled heat pump system (GCHP). The aim of this study is predicting system performance related to ground and air (condenser inlet and outlet) temperatures by using desired models. Performance forecasting is the precondition for the optimal design and energy-saving operation

Hikmet Esen; Mustafa Inalli; Abdulkadir Sengur; Mehmet Esen

2008-01-01

33

A TRNSYS\\/GROCS simulation of the TECH house I ground-coupled series solar-assisted heat pump system  

Microsoft Academic Search

The series solar-assisted heat pump heating system with ground-coupled storage in The University of Tennessee's TECH House I in Knoxville, Tennessee, has been modeled using TRNSYS\\/GROCS and was compared to the experimental performance for the 1980-81 heating season. The simulation results were within 8 percent of the experimental measurements. Both simulation and experimental results showed that ground coupling of thermal

D. J. Roeder; R. L. Reid

1983-01-01

34

Numerical Simulation of a Radiant Heating System Using Solar-Ground Coupled Heat Pump with Seasonal Thermal Storage  

Microsoft Academic Search

To apply the solar-ground coupled heat pump (SGCHP) in severe cold areas, this paper presents the simulation study on a radiant heating system using SGCHP with seasonal thermal storage. The radiant heating system was installed in a detached house in the suburbs of Harbin (126°46'E, 45°45'N). The unit model of each component was given. The performance and operation characteristics of

Xiao Wang; Maoyu Zheng; Wenyong Zhang

2010-01-01

35

Energy and exergy analysis of a ground-coupled heat pump system with two horizontal ground heat exchangers  

Microsoft Academic Search

In this paper we investigate of energetic and exergetic efficiencies of ground-coupled heat pump (GCHP) system as a function of depth trenches for heating season. The horizontal ground heat exchangers (HGHEs) were used and it were buried with in 1m (HGHE1) and 2m (HGHE2) depth trenches. The energy efficiency of GCHP systems are obtained to 2.5 and 2.8, respectively, while

Hikmet Esen; Mustafa Inalli; Mehmet Esen; Kazim Pihtili

2007-01-01

36

Overview of ground coupled heat pump research and technology transfer activities  

NASA Astrophysics Data System (ADS)

Highlights of DOE-sponsored ground coupled heat pump (GCHP) research at Oak Ridge National Laboratory (ORNL) are presented. ORNL, in cooperation with Niagara Mohawk Power Company, Climate Master, Inc., and Brookhaven National Laboratory developed and demonstrated an advanced GCHP design concept with shorter ground coils that can reduce installed costs for northern climates. In these areas it can also enhance the competitiveness of GCHP systems versus air-source heat pumps by lowering their payback from 6 to 7 years to 3 to 5 years. Ground coil heat exchanger models (based primarily on first principles) have been developed and used by others to generate less conservative ground coil sizing methods. An aggressive technology transfer initiative was undertaken to publicize results of this research and make it available to the industry. Included in this effort were an international workshop, trade press releases and articles, and participation in a live teleconference on GCHP technology.

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

37

Optimizing the design of large-scale ground-coupled heat pump systems using groundwater and heat transport modeling  

Microsoft Academic Search

In order to predict the long-term performance of large-scale ground-coupled heat pump (GCHP) systems, it is necessary to take into consideration well-to-well interference, especially in the presence of groundwater flow. A mass and heat transport model was developed to simulate the behavior of this type of system in the Akita Plain, northern Japan. The model was used to investigate different

Hikari Fujii; Ryuichi Itoi; Junichi Fujii; Youhei Uchida

2005-01-01

38

Performance and costs of a roof-sized PV\\/thermal array combined with a ground coupled heat pump  

Microsoft Academic Search

A photovoltaic\\/thermal (PVT) panel is a combination of photovoltaic cells with a solar thermal collector, generating solar electricity and solar heat simultaneously. Hence, PVT panels are an alternative for a combination of separate PV panels and solar thermal collectors. A promising system concept, consisting of 25m2 of PVT panels and a ground coupled heat pump, has been simulated in TRNSYS.

M. Bakker; H. A. Zondag; M. J. Elswijk; K. J. Strootman; M. J. M. Jong

2005-01-01

39

Performance study of underground thermal storage in a solar-ground coupled heat pump system for residential buildings  

Microsoft Academic Search

This paper is performed to analyze the performance of underground thermal storage in a solar-ground coupled heat pump system (SGCHPS) for residential building. Based on the experimental results, the system performance during a longer period is simulated by the unit modeling, and its parametric effects are discussed. The results show that the performance of underground thermal storage of SGCHPS depends

Huajun Wang; Chengying Qi

2008-01-01

40

Seasonal cooling performance of a ground-coupled heat pump system in a hot and arid climate  

Microsoft Academic Search

The goal of the present study is to validate the cooling performance of a ground-coupled heat pump system established in F?rat University, Elaz?? (38.41°N, 39.14°E), Turkey. The cooling load of the test room was 3.1kW at design conditions. The experimental results were obtained from June to September in cooling season of 2003. The ground heat exchanger was used, and it

Mustafa ?nall?; Hikmet Esen

2005-01-01

41

A techno-economic comparison of ground-coupled and air-coupled heat pump system for space cooling  

Microsoft Academic Search

This paper reports a techno-economic comparison between a ground-coupled heat pump (GCHP) system and an air-coupled heat pump (ACHP) system. The systems connected to a test room in Firat University, Elazig (38.41°N, 39.14°E), Turkey, were designed and constructed for space cooling. The performances of the GCHP and the ACHP system were experimentally determined. The experimental results were obtained from June

Hikmet Esen; Mustafa Inalli; Mehmet Esen

2007-01-01

42

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

E-print Network

- Comparison of heat exchanger sizing methods for Houston. . . . . 9. 2- Comparison of heat exchanger sizing methods for Dallas. . . . . . . . 99 99 DEFINITION OF SYMBOLS A COP P SEER ron Surface Area (m~) Specific Heat (I/kg-'K) Coefficient...- Comparison of heat exchanger sizing methods for Houston. . . . . 9. 2- Comparison of heat exchanger sizing methods for Dallas. . . . . . . . 99 99 DEFINITION OF SYMBOLS A COP P SEER ron Surface Area (m~) Specific Heat (I/kg-'K) Coefficient...

Gonzalez, Jose Antonio

2012-06-07

43

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

E-print Network

, savings of greenhouse gas emissions and reasonable environmental safety. Furthermore, the Environmental greenhouse gas emissions produced in developed countries, being approximately 60% produced by cooling (GCHP) systems represent a tech- nically viable technology for heating, cooling and domestic hot water

Fernández de Córdoba, Pedro

44

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

SciTech Connect

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.

Andrews, J.W.

1980-09-01

45

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)

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.

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

46

Comparison between the energy performance of a ground coupled water to water heat pump system and an air to water heat pump system for heating and cooling in typical conditions of the European Mediterranean coast  

Microsoft Academic Search

The investigation presented in this article was aimed at demonstrating the technical and economical feasibility of using ground source heat pump systems in mixed climate applications, where cooling requirements are dominant. We show an experimental comparison between a ground coupled heat pump system and a conventional air to water heat pump system, focussing at the heating and cooling energy performance.

J. F. Urchueguía; M. Zacarés; J. M. Corberán; Á. Montero; J. Martos; H. Witte

2008-01-01

47

Experimental study of a solar-assisted ground-coupled heat pump system with solar seasonal thermal storage in severe cold areas  

Microsoft Academic Search

This paper presents the experimental study of a solar-assisted ground-coupled heat pump system (SAGCHPS) with solar seasonal thermal storage installed in a detached house in Harbin. The solar seasonal thermal storage was conducted throughout the non-heating seasons. In summer, the soil was used as the heat sink to cool the building directly. In winter, the solar energy was used as

Xiao Wang; Maoyu Zheng; Wenyong Zhang; Shu Zhang; Tao Yang

2010-01-01

48

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

E-print Network

Hourly Weather Data Generator for Driving Energy Simulation and Equipment Design Software for Buildings", Proceedings for the Conference on Building Simulation, Sophia, Antipolis, Nice, France. 9. EPRI, Electrical Power Research Institute., 1989... Hourly Weather Data Generator for Driving Energy Simulation and Equipment Design Software for Buildings", Proceedings for the Conference on Building Simulation, Sophia, Antipolis, Nice, France. 9. EPRI, Electrical Power Research Institute., 1989...

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

1994-01-01

49

Technical and economic feasibility of horizontal, multiple shallow-well, and deep-well ground coupling for residential heat pump applications  

NASA Astrophysics Data System (ADS)

An analytical assessment of ground-coupled heat pump systems in ten representative cities of the United States showed that simple payback relative to air-source heat pumps is shortest for deep-well ground-coil systems and ranged from 8 to 10 years in three cities, 12 to 15 years in two cities, and above 30 years in Seattle which has low electrical rates and space conditioning loads. Simple payback with any of three types of ground-coil systems is non-existent in Phoenix and Houston, which have highest cooling loads and low water table. Simple payback with horizontal ground-coil systems was only slightly longer than with deep-well systems. Deep-well ground-coil systems had shorter simple payback than multiple shallow-well systems, particularly in areas where deep wells can be drilled into rock layers. Life-cycle costs with a real discount rate of 2.0 percent for horizontal and deep-well ground-coil systems were shorter than that for air-source systems in all cities except for Phoenix, Houston, and Seattle. Seasonal heating coefficient of performance for the ground-coupled systems varied between 2.0 to 3.1 compared to 1.7 to 2.0 for air-source systems. Values of seasonal cooling coefficient of performance for ground-coupled systems were highest with the single deep-well coil. Cooling COP values with a horizontal coil were generally equal to or lower than values for air-source systems. Cooling COP values for air-source systems were higher than values for ground-coupled systems in southern climates with higher cooling loads.

Fischer, R. D.; Stickford, G. H., Jr.

1984-01-01

50

Experimental analysis and mathematical modeling of a direct-expansion ground-coupled heat-pump system  

Microsoft Academic Search

The author the author investigates a direct expansion heat pump system that is uniquely coupled to the earth through a heat transfer concentrator (GLHXC, Ground Loop Heat Exchanger Concentrator). A description of the system and its instrumentation with a presentation of performance results for winter and summer operation are included. The results are compared to experimental data obtained from four

Safemazandarani

1989-01-01

51

Development of a Validated Model of Ground Coupling  

SciTech Connect

A research program at Brookhaven National Laboratory (BNL) studies ground coupling, the use of the earth as a heat source/sink or storage element for solar heat pump space conditioning systems. This paper outlines the analytical and experimental research to date toward the development of an experimentally validated model of ground coupling and based on experimental results from December, 1978 to September, 1979, expores sensitivity of present model predictions to variations in thermal conductivity and other factors. Ways in which the model can be further refined are discussed.

Metz, P.D.

1980-01-01

52

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

E-print Network

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...

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

2002-01-01

53

Characteristics Of Vertical Mantle Heat Exchangers For Solar Water Heaters  

Microsoft Academic Search

The flow structure in vertical mantle heat exchangers was investigated using a full-scale tank designed to facilitate flow visualisation. The flow structure and velocities in the mantle were measured using a particle Image Velocimetry (PIV) system. A CFD simulation model of vertical mantle heat exchangers was also developed for detailed evaluation of the heat flux distribution over the mantle surface.

L. J. Shah; G. L. Morrison; M. Behnia

1999-01-01

54

Ground-coupling techniques for cooling in desert regions  

SciTech Connect

Results compiled from a parametric study of several variables that effect ground-coupling techniques for buildings in hot, arid regions are discussed. Finite difference models were devised and analyzed by the computer program SPICE to quantify these effects. Earlier results showed that berming or burying a structure to a depth of 3.6 m and insulating only the roof plane reduce the cooling load by 40% and virtually eliminate the heating load compared to a well-insulated building on the surface. Soil isotherm contours and heat flux results from surface and earth-integrated buildings are presented to further compare their thermal behavior.

Bircher, T. L.

1981-04-01

55

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

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

56

Steam condensation heat transfer on smooth and profiled vertical tubes  

Microsoft Academic Search

In this paper the results of an investigation into condensation heat transfer of quiescent steam on vertical smooth and profiled tubes with annular grooves are presented. The film REynolds number varied 20 to 3000, the Pradtl number from 1.14 to 1.77. The enhancement of heat transfer during steam condensation on profiled tubes was observed in the all regimes under investigation.

Mikhaylov

1991-01-01

57

Boiling heat transfer enhancement in subsurface horizontal and vertical tunnels  

SciTech Connect

Complex experimental investigations of boiling heat transfer on structured surfaces covered with perforated foil were taken up. Experimental data were discussed for two kinds of enhanced surfaces formed by joined horizontal and vertical tunnels: tunnel structures (TS) and narrow tunnel structures (NTS). The experiments were carried out with water, ethanol and R-123 at atmospheric pressure. The TS and NTS surfaces were manufactured out of perforated copper foil of 0.05 mm thickness (hole diameters: 0.3, 0.4, 0.5 mm) sintered with the mini-fins, formed on the vertical side of the 5 mm high rectangular fins and horizontal inter-fin surface. The effects of hole (pore) diameters, tunnel pitch for TS and tunnel width for NTS on nucleate pool boiling were examined. Substantial enhancement of heat transfer coefficient was observed. The investigated surfaces showed boiling heat transfer coefficients similar to those of existing structures with subsurface tunnels, but at higher heat fluxes range. (author)

Pastuszko, Robert [Chair of Thermodynamics and Fluids Mechanics, The Kielce University of Technology, Al. Tysiaclecia P.P. 7, 25-314 Kielce (Poland)

2008-09-15

58

Conjugate heat transfer analysis of a heat generating vertical plate  

Microsoft Academic Search

This paper mainly deals with conjugate heat transfer problem pertinent to rectangular fuel element of a nuclear reactor dissipating heat into an upward moving stream of liquid sodium. Introducing boundary layer approximations, the equations governing the flow and thermal fields in the fluid domain are solved simultaneously along with two-dimensional energy equation in the solid domain by satisfying the continuity

S. Jahangeer; M. K. Ramis; G. Jilani

2007-01-01

59

Numerical modelling of geothermal vertical heat exchangers for the short time analysis using the state model size reduction technique  

Microsoft Academic Search

According to the introduction of a dynamic operating mode in ground-coupled heat pump systems, a short time analysis within and around borehole heat exchangers is required in the modern geothermal system simulation. A numerical modelling could be a proper answer for this challenge. However, the numerical model is time consuming and necessitates a large memory particularly in such large systems.

Eui-Jong Kim; Jean-Jacques Roux; Gilles Rusaouen; Frédéric Kuznik

2010-01-01

60

Heat transfer analysis of boreholes in vertical ground heat exchangers  

Microsoft Academic Search

A ground heat exchanger (GHE) is devised for extraction or injection of thermal energy from\\/into the ground. Bearing strong impact on GHE performance, the borehole thermal resistance is defined by the thermal properties of the construction materials and the arrangement of flow channels of the GHEs. Taking the fluid axial convective heat transfer and thermal “short-circuiting” among U-tube legs into

Heyi Zeng; Nairen Diao; Zhaohong Fang

2003-01-01

61

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

-Coupled Envelope in Building Thermal Simulation Software. Energy and Buildings. 40: 476-485. Zhong, Z., Braun, J.E. 2007. A simple method for estimating heat transfer in slab-on-ground floors. Building and Environment. 42:1071-1080. ESL-TR-10-08-03 ...-Coupled Envelope in Building Thermal Simulation Software. Energy and Buildings. 40: 476-485. Zhong, Z., Braun, J.E. 2007. A simple method for estimating heat transfer in slab-on-ground floors. Building and Environment. 42:1071-1080. ESL-TR-10-08-03 ...

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

62

Convective heat transfer with chemical transformations in a vertical channel  

NASA Astrophysics Data System (ADS)

A theoretical model describing laminar free convection flow of hydrogen-air mixture taking into account an exothermic heterogeneous reaction in a vertical channel with autocatalytic coating is presented. It is shown that the surface of channel walls can be subdivided into areas with different reaction flow patterns: the initial region in which the reaction rate experiences a very rapid growth and the heat flowrate on the wall has a maximum, and the region corresponding to intersection of boundary layers, in which enhancement of the hydrogen oxidation reaction is observed. The results from a numerical experiment confirmed the conclusions obtained from analytical assessments.

Grigoruk, D. G.; Kondratenko, P. S.; Nikol'Skii, D. V.; Chizhov, M. E.

2011-06-01

63

New correlations for mixed turbulent natural and forced convection heat transfer in vertical tubes  

Microsoft Academic Search

This work deals with mixed natural and forced turbulent convection heat transfer in vertical tubes. It summarizes the experimental results available in literature for both aiding and opposing flow conditions and presents own experimental results that concentrated on the influence of length-to-diameter ratio and of heat and mass flux directions on heat transfer in vertical tubes. Finally, it presents two

T. Aicher; H. Martin

1997-01-01

64

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

Microsoft Academic Search

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

Yuehong Bi; Linger Chen; Chih Wu

2001-01-01

65

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

NASA Astrophysics Data System (ADS)

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.

Zeng, Heyi; Diao, Nairen; Fang, Zhaohong

2003-02-01

66

CFD analysis of heat transfer within a bottom heated vertical concentric cylindrical enclosure  

NASA Astrophysics Data System (ADS)

The CFD analysis of heat transfer within a bottom heated vertical concentric cylindrical enclosure is important with respect to the process in the chemical and process industries. The research work focuses on the CFD analysis of the enclosure with respect to the machines used for the segregation of chemicals in the chemical industries. The CFD simulations are performed to study the effects of inner cylinder material and outer cylinder geometric configurations on the heat transfer mechanism in the enclosure. The CFD simulations are conducted at a bottom disc temperature of 393 K and compared with the published results at a temperature of 433 K. This research study depicts the behavior of bottom heated vertical concentric cylindrical enclosure at different bottom disc temperatures. This study also investigates the heat transfer mechanism of the enclosure using different inner cylinder materials and different configurations of the outer cylinder. In such enclosures a uniform temperature is required for the segregation of chemicals. A more uniform temperature is observed in the enclosure by using aluminum inner cylinder of the bottom disc and using two different diameter outer cylinders as compared to the mild steel and stainless steel.

Hussain Malik, Asif; Shah, Ajmal; Khushnood, Shahab

2013-06-01

67

New analytical solution for sizing vertical borehole ground heat exchangers in environments with significant groundwater flow: Parameter estimation from thermal response test data  

Microsoft Academic Search

Accurate prediction of transient subsurface heat transfer is important in sizing ground heat exchangers in ground coupled heat pump systems. This article examines three analytical solutions for the heat transfer characteristics around closed-loop borehole heat exchangers in significant groundwater flow. The first solution is the so-called moving line source solution, the second is based on the groundwater g-function, and the

Andrew Chiasson; Amanda O’Connell

2011-01-01

68

Numerical study of natural convection in a vertical porous annulus with discrete heating  

E-print Network

Numerical study of natural convection in a vertical porous annulus with discrete heating M. Sankar online 20 December 2010 Keywords: Natural convection Annulus Discrete heating Porous medium Radii ratio Brinkman-extended Darcy model a b s t r a c t In this paper natural convection flows in a vertical annulus

Lopez, John M.

69

Critical heat flux prediction for saturated flow boiling of water in vertical tubes  

Microsoft Academic Search

This study presents a new analytical model for the prediction of the critical heat flux (CHF) in water saturated flow boiling in round vertical and uniformly heated pipes. The CHF is assumed to occur in annular flow when the liquid film vanishes at the exit section of the heated channel. Channel pressure drop is calculated using the Friedel correlation. Liquid

Gian Piero Celata; Kaichiro Mishima; Giuseppe Zummo

2001-01-01

70

Selecting the Design Entering Water Temperature for Vertical Geothermal Heat Pumps in Cooling-Dominated Applications  

Microsoft Academic Search

At a military base in the Southeastern United States, an energy services company (ESCO) has proposed to retrofit more than 1,000 family residences with geothermal heat pumps as part of an energy savings performance contract (ESPC). Each residence is to have one heat pump with its own ground heat exchanger consisting of two or more vertical bores. A design firm

John A Shonder; Jeff W. Thornton; Patrick Hughes

2001-01-01

71

Analysis of film condensation heat transfer inside a vertical micro tube with consideration of the meniscus  

E-print Network

0017-9310(03)00293-X International Journal of Heat and Mass Transfer 46 (2003) 4669­4679 www and mass transfer processes in a micro heat pipe. The liquid flow in the triangular-shaped cornersAnalysis of film condensation heat transfer inside a vertical micro tube with consideration

Zhao, Tianshou

72

Gas heat transfer in a heated vertical channel under deteriorated turbulent heat transfer regime  

E-print Network

Passive cooling via natural circulation of gas after a loss of coolant (LOCA) accident is one of the major goals of the Gas-cooled Fast Reactor (GFR). Due to its high surface heat flux and low coolant velocities under ...

Lee, Jeongik

2007-01-01

73

Gas Heat Transfer in a Heated Vertical Channel under Deteriorated Turbulent Heat Transfer Regime  

E-print Network

Passive cooling via natural circulation of gas after a loss of coolant (LOCA) accident is one of the major goals of the Gas-cooled Fast Reactor (GFR). Due to its high surface heat flux and low coolant velocities under ...

Lee, Jeongik

74

Investigation on air to ground coupled waves and other geophysical studies  

NASA Astrophysics Data System (ADS)

This work describes three geophysical investigations in the Western United States. The first section is an investigation regarding the amplitude of air to ground coupled waves recorded at the Nevada Seismic Array. The waves are modeled as loads propagating with sound speed velocities, and the resulting transfer functions are compared with observations. The results are also in agreement with the current held geological information obtained from shallow refraction profiles. In the second section new heat flow values for several sites in southwest are obtained and interpreted in terms of local and regional geology. The main result is that the Ouachita tectonic front represents an important thermal boundary. A cross section over the front zone suggest heat flow values of 48 mW/m2 in the Fort Worth Basin, 61 mW/m2 exactly in the front zone and then drops to 55 in the interior zone. In addition several other problems are addressed. The third section discusses heat flow patterns in the Yellowstone Lake, and the link between heat flow and structural features. Simple conductive computations suggest average heat flow of 200 mW/m2, while average measured heat flow over the entire lake is estimated at 1200 mW/m 2. Therefore the measured heat loss must be raised by convective heat and Nusselt numbers at least 6 are obtained. The implications for the natural hazard assessment are also discussed.

Negraru, Petru Teodor

75

Residential Vertical Geothermal Heat Pump System Models: Calibration to Data  

Microsoft Academic Search

A detailed component-based simulation model of a geothermal heat pump system has been calibrated to monitored data taken from a family housing unit located at Fort Polk, Louisiana. The simulation model represents the housing unit, geothermal heat pump, ground heat exchanger, thermostat, blower, and ground-loop pump. Each of these component models was 'tuned' to better match the measured data from

Jeff W. Thornton; T. P. McDowell; John A Shonder; Patrick Hughes; D. Pahud; G. Hellstrom

1997-01-01

76

An experimental study of naturally driven heated air flow in a vertical pipe  

Microsoft Academic Search

Specifications of warm air flow within a vertical pipe which is induced by the buoyancy effect were investigated in this study. Air from surroundings was directed into a heating chamber connected to a vertical pipe to establish a flow within the pipe. The temperature and the velocity were measured at different points within the stable flow and the mean values

Mostafa Rahimi; Mohammad Mehdi Bayat

2011-01-01

77

Vertical heat flux and lateral mass transport in nonlinear internal waves  

E-print Network

Click Here for Full Article Vertical heat flux and lateral mass transport in nonlinear internal, and turbulent dissipation permit quantification of the nonlinear internal wave (NLIW) contribution to vertical unit alongshelf dimension) by NLIWs is estimated as 0.3 m2 s-1 . This is comparable to a weak

78

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

E-print Network

EFFECT OF SURFACTANT ON EVAPORATIVE HEAT TRANSFER COEFFICIENTS IN VERTICAL FILM FORCED CONVECTION A Thesis by BASIT HUSAIN SHAH Submitted to the Graduate College of Texas A8M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1972 Major Subject: Chemical Engineering EFFECT OF SURFACTANT ON EVAPORATIVE HEAT TRANSFER COEFFICIENTS IN VERTICAL FILM FORCED CONVECTION A Thesis by BASIT HUSAIN SHAH Approved as to style and content by: 2~m Chairman...

Shah, Basit Husain

2012-06-07

79

Film flow and heat transfer during condensation of steam on inclined and vertical nonround tubes  

NASA Astrophysics Data System (ADS)

We describe a mathematical model for calculating heat transfer during film condensation of stagnant steam on inclined and vertical smooth tubes with cross sections of arbitrary shape that takes into account the action of surface tension forces. The heat-transfer coefficients are calculated, and the hydrodynamic pattern is presented in which a condensate film flows over the surface of nonround inclined and vertical tubes with cross-section of different shapes.

Nikitin, N. N.; Semenov, V. P.

2008-03-01

80

Experimental investigation of turbulent natural convection in a vertical water channel with symmetric heating: flow and heat transfer  

E-print Network

, an experimental model is developed in order to study the coupling between the flow and heat transfer of a natural, Turbulent heat transfer 1. Introduction Governments are committed to reducing greenhouse gas pro- ductionExperimental investigation of turbulent natural convection in a vertical water channel

Paris-Sud XI, Université de

81

Experimental study of natural convection heat transfer from vertical array of isothermal horizontal elliptic cylinders  

SciTech Connect

Laminar free convection heat transfer from vertical array of horizontal isothermal elliptic cylinders with vertical major axis has been experimentally investigated. Experiments were carried out using Mach-Zehnder interferometer with the cylinder spacing from two to five cylinder major axis and at Rayleigh numbers in the range between 10{sup 3} and 2.5 x 10{sup 3}. The effects of cylinder spacing and Rayleigh number on the heat transfer from the individual cylinder and the array were investigated. It is found that the free convection heat transfer from any individual cylinder in the array depends on the Rayleigh number, cylinders separation distance and cylinder position in the array. Heat transfer correlations have been developed for both the individual cylinder in the array and the array. Also, a heat transfer correlation has been proposed for a single elliptic cylinder with vertical major axis and is compared with earlier works. (author)

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

2007-10-15

82

Geothermal Energy Utilization via Effective Design of Ground-Coupled  

E-print Network

Heat Pump ­ Geothermal heat pump basics ­ Previous research · Geothermal Heat Exchange System R on roads ­ District heating systems ­ Various industrial processes · Geothermal Heat Pumps ­ Heating) #12;More on Geothermal Heat Pump · EPA on GHP (1993) ­ GeoExchange (GHP) systems are the most energy

Tennessee, University of

83

Method and apparatus for determining vertical heat flux of geothermal field  

DOEpatents

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.

Poppendiek, Heinz F. (LaJolla, CA)

1982-01-01

84

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

Microsoft Academic Search

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

Hua Su; Xungen Shi

2010-01-01

85

Particle image velocimetry measurements of vortex rings head-on collision with a heated vertical plate  

E-print Network

Particle image velocimetry measurements of vortex rings head-on collision with a heated vertical online 20 May 2010 We report particle image velocimetry measurements of the collision of a vortex ring with a heated wall kept at constant temperature. We consider the case when both the vortex ring and the thermal

Boyer, Edmond

86

Supermarket with Ground Coupled Carbon Dioxide Refrigeration Plant  

E-print Network

) answers? ? Natural refrigerants ? Use of natural heat sinks and sources ? Covered refrigerated shelves ? Waste heat recovery ? Highly insulated building envelope ? Energy efficient heating and ventilating 1. Backgrounds ? Fraunhofer ISE 7 En...) answers? ? Natural refrigerants ? Use of natural heat sinks and sources ? Covered refrigerated shelves ? Waste heat recovery ? Highly insulated building envelope ? Energy efficient heating and ventilating 1. Backgrounds ? Fraunhofer ISE 7 En...

Rehault, N.

2012-01-01

87

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

NASA Technical Reports Server (NTRS)

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.

Eckert, E R G; Diaguila, A J

1955-01-01

88

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 Line Source Theory; g-functions 1. Introduction Ground source heat pump (GSHP) systems are a widely approach with a parametric study. Keywords - Ground Source Heat Pumps; Borehole Heat Exchangers; Finite

89

The transfer of heat and mass to a vertical plate under frosting conditions  

E-print Network

THE TRAESFPIR OF HEAT . 'ND NASH 10 A VERTICAL PLATE UNDER FROSTING CONDITIONS A Thesis Louis Joseph Poth, Jr. Submitted to the Graduate School of the Agricultural and Nechanioal College of Texas in partial fulfili ment of the requirements... of the Husselt-Grashof correlation for heat transfer. coefficient of saturation temper ture and concen- tration gradient correlation, for small temper- ature difference. ooefficient of frost specific gravity-thermal oonductivity correlation. coefficient...

Poth, Louis Joseph

2012-06-07

90

Heat transfer in a high vertical enclosure with fins attached to one of the side walls  

Microsoft Academic Search

A numerical model is developed of heat transfer in a high vertical narrow enclosure in the presence of fins on one of the\\u000a isothermal side walls. The Navier—Stokes equations were solved numerically in two-dimensional formulation. It is demonstrated\\u000a that the mean coefficient of heat transfer over the channel surface for adiabatic fins first increases with the number of\\u000a fins to

V. I. Terekhov; V. V. Terekhov

2006-01-01

91

Non-Darcy mixed convection in a vertical porous channel with asymmetric wall heating  

Microsoft Academic Search

A numerical study of buoyancy-assisted mixed convection in a vertical porous channel with asymmetric heating at the walls was performed. The Brinkman-Forchheimer-extended Darcy model was used to account for both the inertia and the viscous effects. The evolution of mixed convection in the entrance region was examined in detail. Both uniform wall temperature and uniform wall heat flux conditions were

H. A. Hadim; G. Chen

1994-01-01

92

Parameter estimation based on vertical heat transport in the surficial zone  

Microsoft Academic Search

Measured groundwater temperatures in the surficial zone are dependent on the properties of porous media and vertical flow\\u000a velocity. Sensitivity analyses, collinear diagnostics and an inverse numerical solution to the one-dimensional heat-transport\\u000a equation are used to determine which parameters can be estimated from temperature measurements in the surficial zone. This\\u000a is done for heat transport in the saturated zone considering

Alexander Vandenbohede; Luc Lebbe

2010-01-01

93

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

Microsoft Academic Search

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

Hikmet Esen; Mustafa Inalli

2010-01-01

94

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

Microsoft Academic Search

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

Dmitry A Bratsun; Alexej V Zyuzgin; Gennady F Putin

2003-01-01

95

Bond graph model of a vertical U-tube steam condenser coupled with a heat exchanger  

Microsoft Academic Search

A simulation model for a vertical U-tube steam cond enser in which the condensate is stored at the bottom well is developed in this pape r. The U-tubes carrying the coolant are partially submerged in the stored condensate and th us the bottom well acts as a heat exchanger. The storage of hydraulic and thermal ene rgies is represented using

K. Medjaher; Arun K. Samantaray; Belkacem Ould Bouamama

2009-01-01

96

MODELING OF HEAT AND MASS TRANSFER IN A ROTATING VERTICAL POROUS CHANNEL WITH HALL CURRENT  

Microsoft Academic Search

In this study we have obtained an exact solution to the problem of heat and mass transfer in a rotating vertical porous channel taking into account the effects of Hall current. A strong magnetic field of uniform strength is applied along the axis of rotation. The entire system rotates about the axis normal to the plates with a uniform angular

Sahin Ahmed; Joaquín Zueco

2011-01-01

97

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

Microsoft Academic Search

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

Philipp Blum; Gisela Campillo; Thomas Kölbel

2011-01-01

98

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

SciTech Connect

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.

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

2006-01-01

99

Heat transfer in vertical Bridgman growth of oxides - Effects of conduction, convection, and internal radiation  

NASA Technical Reports Server (NTRS)

In the present investigation of crystalline phase internal radiation and heat conduction during the vertical Bridgman growth of a YAG-like oxide crystal, where transport through the melt is dominated by convection and conduction, heat is also noted to be conducted through ampoule walls via natural convection and enclosure radiation. The results of a quasi-steady-state axisymmetric Galerkin FEM indicate that heat transfer through the system is powerfully affected by the optical absorption coefficient of the crystal. The coupling of internal radiation through the crystal with conduction through the ampoule walls promotes melt/crystal interface shapes that are highly reflected near the ampoule wall.

Brandon, S.; Derby, J. J.

1992-01-01

100

Heat Transfer to Supercritical Water in Gaseous State or Affected by Mixed Convection in Vertical Tubes  

SciTech Connect

The results on heat transfer to supercritical water heated above the pseudo-critical temperature or affected by mixed convection flowing upward and downward in vertical tubes of 6.28-mm and 9.50-mm inside diameter are presented. Supercritical water heat-transfer data were obtained at a pressure of 23.5 MPa, mass flux within the range from 250 to 2200 kg/(m{sup 2}s), inlet temperature from 100 to 415 deg. C and heat flux up to 3.2 MW/m{sup 2}. Temperature regimes of the tubes cooled with supercritical water in a gaseous state (i.e., supercritical water at temperatures beyond the pseudo-critical temperature) were stable and easily reproducible within a wide range of mass and heat fluxes. An analysis of the heat-transfer data for upward and downward flows enabled to determine a range of Gr/Re{sup 2} values corresponding to the maximum effect of free convection on the heat transfer. It was shown that: 1) the heat transfer coefficient at the downward flow of water can be higher by about 50% compared to that of the upward flow; and 2) the deteriorated heat-transfer regime is affected with the flow direction, i.e., at the same operating conditions, the deteriorated heat transfer may be delayed at the downward flow compared to that at the upward flow. These heat-transfer data are applicable as the reference dataset for future comparison with bundle data. (authors)

Pis'menny, E.N.; Razumovskiy, V.G.; Maevskiy, E.M.; Koloskov, A.E. [National Technical University of Ukraine, 37, Prospect Peremohy, 03056, Kyiv-56 (Ukraine); Pioro, I.L. [Chalk River Laboratories - AECL, 2251 Speakman Drive, Mississauga, ON, L5K 1B2 (Canada)

2006-07-01

101

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

E-print Network

Boiling 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 of boiling flows in microscale's geometry, it is vital to quantify these transfers. To achieve this goal

102

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

SciTech Connect

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)

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

103

Experimental investigation of the local heat transfer in a vertical gas-liquid slug unit  

NASA Astrophysics Data System (ADS)

Heat transfer mechanism in two-phase flows and particularly in vertical slug flow is of high interest both for basic hydrodynamic research and for industrial applications. Two-phase slug flow is highly complicated and only a limited number of heat transfer studies have been carried out. The flow field around a single Taylor bubble propagating in a vertical pipe can be subdivided into three distinct hydrodynamic regions: the gas bubble surrounded by a thin liquid film, a highly turbulent liquid wake in the vicinity of the bubble bottom, and the far wake region. Experimental and theoretical works were presented during the last decades investigating the hydrodynamic parameters in each region. Due to the complexity and intermittent nature of slug flow the existing data on the heat transfer in slug flow is limited to a narrow range of operational conditions. To improve the understanding of the heat transfer mechanism in slug flow a new experimental setup was constructed. A part of the vertical pipe wall was replaced by a thin metal foil heated by electrical current. An IR video camera was used to determine the temporal variation of the instantaneous temperature field along the foil at two locations: at the thermal entrance region and at the upper part of the foil where thermal boundary is thicker. The video camera was synchronized with a sensor that determined the instantaneous location of the Taylor bubble. The results of the instantaneous heat transfer measurements along the liquid film and in the wake of the Taylor bubble can be correlated with the detailed velocity measurements carried out in the same facility (Shemer et al. 2007)[1]. The effect of the local hydrodynamic parameters on the heat transfer coefficient in each region is examined.

Babin, Valery; Shemer, Lev; Barnea, Dvora

2012-03-01

104

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

Constructal multi-scale package of vertical channels with natural convection and maximal heat-scale structures in natural convection with the objective of maximizing the heat transfer density, or the heat, Constructal multi-scale structure for maximal heat transfer density in natural convection, International

Kihm, IconKenneth David

105

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

SciTech Connect

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)

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

106

Direct Numerical Simulation of Vertical Rotating Turbulent Open-Channel Flow with Heat Transfer  

Microsoft Academic Search

Direct numerical simulation of vertical rotating open-channel flow with heat trans- fer has been carried out for the rotation number N¿ from 0 to 0.1, the Prandtl number 1, and the Reynolds number 180 based on the friction velocity of non-rotating flow and the height of the channel. The objective of this study is to reveal the effect of rotation

Bu-Yang Li; Nan-Sheng Liu; Xi-Yun Lu

2006-01-01

107

Wall heat flux partitioning during subcooled forced flow film boiling of water on a vertical surface  

Microsoft Academic Search

Subcooled flow film boiling experiments were conducted on a vertical flat plate, 30.5cm in height, and 3.175cm wide with forced convective upflow of subcooled water at atmospheric pressure. Data have been obtained for mass fluxes ranging from 0 to 700kg\\/m2s, inlet subcoolings ranging from 0 to 25°C and wall superheats ranging from 200 to 400°C. Correlations for wall heat transfer

Phani K. Meduri; Gopinath R. Warrier; Vijay K. Dhir

2009-01-01

108

Unsteady mixed convective flow and heat transfer in a vertical corrugated channel with composite porous media  

NASA Astrophysics Data System (ADS)

An unsteady mixed convective flow and heat transfer in a vertical corrugated channel containing porous and fluid layers are considered. The equations of momentum and energy are solved under appropriate boundary and interface conditions with the assumption that the solution consists of a mean part and a perturbed one. The exact solutions are obtained in the long-wave approximation. Separate solutions are matched at the interface with the use of suitable matching conditions. The effects of pertinent parameters, such as the Grashof number, viscosity ratio, width ratio, conductivity ratio, frequency, and the wave parameter on the flow field and heat transfer characteristics are studied.

Umavathi, J. C.; Shekar, M.

2013-07-01

109

Vortex ring head-on collision with a heated vertical plate  

NASA Astrophysics Data System (ADS)

We report experimental results of the normal impact of a vortex ring in air on a vertical heated plate at constant temperature. We address the case in which the natural convection boundary layer is laminar and the vortex ring is stable. Vortex rings are created by pushing air through a circular exit orifice of a cavity, using a piston-cylinder system. The impinging vortex ring perturbs both the thermal and dynamical boundary layers where we measure the total heat flux exchanged by the heated plate and visualize the vortex motion during the impact. This unsteady impingement process is investigated for different vortex sizes and self-induced velocities, characterized by the Reynolds number of the ring. As a result, a localized heat transfer enhancement is originated by the ring impingement, which increases with the Reynolds number.

Arévalo, G.; Hernández, R. H.; Nicot, C.; Plaza, F.

2007-08-01

110

Vertically integrated sensible-heat budgets for stable nocturnal boundary layers  

NASA Astrophysics Data System (ADS)

The stable nocturnal boundary layer is commonly viewed or modelled as a balance between the temperature tendency (cooling) and vertical heat-flux divergence. Sometimes the radiative-flux divergence is also included. This perspective has dictated the design of field experiments for investigating stable nocturnal boundary layers.Tower-based micrometeorological data from three field campaigns are analysed to evaluate the vertically integrated sensible-heat budget for nocturnal stable conditions. Our analysis indicates frequent occurrence of large imbalance between the temperature tendency and vertical heat-flux divergence terms. The values of the radiative-flux divergence are generally too small and sometimes of the wrong sign to explain the residual. An analysis of random flux errors and uncertainties in the tendency term indicate that such errors cannot explain large imbalances, suggesting the importance of advection of temperature or possibly the divergence of mesoscale fluxes. The implied role of advection is consistent with circumstantial evidence. Even weak surface heterogeneity can create significant horizontal gradients in stable boundary layers. However, it is shown that existing field data and observational strategy do not allow adequate evaluation of advection and mesoscale flux divergence terms.

Nakamura, Reina; Mahrt, L.

2006-01-01

111

On natural convection in vertical porous enclosures due to opposing fluxes of heat and mass prescribed at the vertical walls  

NASA Astrophysics Data System (ADS)

A two-dimensional mathematical model based on Darcy's law with Boussinesq approximation has been used to study double-diffusive natural convection in a rectangular fluid-saturated vertical porous enclosure subject to opposing and horizontal gradients of heat and solute. Results are presented for 50 less than or equal to R(sub c) less than or equal to 250, 0.01 less than or equal to N less than or equal to 10, 10 less than or equal to Le less than or equal to 40 and 1 less than or equal to A less than or equal to 10, where R(sub c), N, Le and A correspond to the solutal Rayleigh-Darcy number, inverse of buoyancy ratio, Lewis number and enclosure aspect ratio, respectively. The numerical integration of the full problem reveals that for sufficiently large R(sub c), Le and A, there is a domain of N in which one obtains oscillating convection. Outside this domain, the solution approaches steady-state convection, for which analytical solutions are developed and presented. The agreement between the analytical and the numerical solutions is shown to be satisfactory.

Alavyoon, Farid; Masuda, Yoshio; Kimura, Shigeo

1994-01-01

112

Influence of fluid-property variation on turbulent convective heat transfer in vertical annular channel flows.  

SciTech Connect

Influence of strongly-varying properties of supercritical-pressure fluids on turbulent convective heat transfer is investigated using direct numerical simulation. We consider thermally-developing upward flows in a vertical annular channel where the inner wall is heated with a constant heat flux and the outer wall is insulated. CO2 is chosen as the working fluid at a pressure to 8 Mpa, and the inlet Reynolds number based on the channel hydraulic diameter and the bulk velocity is Re0 = 8900. It is shown that turbulent convective heat transfer characteristics of supercritical flow are significantly different from those of constant-property flow mainly due to spatial and temporal variations of fluid density. Non-uniform density distribution causes fluid particles to be accelerated either by expansion or buoyancy force near the heated wall, while temporal density fluctuations change the transport characteristics of turbulent heat and momentum via the buoyancy production terms arising from the correlations such as p1u1x, p1u1r and p1h1. Among various turbulence statistics, the streamwise turbulent heat flux shows a very peculiar transitional behavior due to the buoyancy effect, changing both in sign and magnitude. Consequently, a non-monotonic temperature distribution is developed in the flow direction, causing severe impairment of heat transfer in supercritical flows.

D. M. McEligot; J. H. Bae; J. Y. Yoo; H. Choi; James R. Wolf

2005-10-01

113

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

PubMed Central

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

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

2014-01-01

114

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

PubMed

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

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

2014-01-01

115

Computational hydromagnetic mixed convective heat and mass transfer through a porous medium in a non-uniformly heated vertical channel with heat sources and dissipation  

Microsoft Academic Search

In this paper we discuss the combined effect of convective Heat and mass transfer on hydromagnetic electrically conducting viscous, incompressible fluid through a porous medium in a vertical channel bounded by flat walls. A uniform magnetic filed of strength H0 is applied transverse to the bounding walls. Assuming the magnetic Reynolds number to be small, we neglect the induced magnetic

P. Raveendra Nath; P. M. V. Prasad; D. R. V. Prasada Rao

2010-01-01

116

Natural Convection Heat and Mass Transfer from Falling Films in Vertical Channels  

NASA Astrophysics Data System (ADS)

In the design of solar collector/regenerators for use in open cycle absorption refrigeration (OCAR) units, the problem of predicting evaporation rates and solution temperatures is of paramount importance in determining overall cycle performance. This transport of heat and mass is dominated by natural convection with buoyant forces primarily generated as a result of film heating by the solar flux, but aided by the evaporation of water (the lighter species) into the rising moist air stream. In order to better understand the mechanism of these combined buoyant interactions, the governing equations for natural convection flow in a vertical channel bounded by a heated falling film (simulating a glazed collector/regenerator) were solved using several different finite difference techniques. The numerical results were validated against existing experimental and numerical results for simplified boundary conditions. The appropriate nondimensionalization for the falling film boundary condition was established, ostensibly for the first time, and a parametric study for an air-water vapor mixture has been presented. Curve fits to the numerical results were determined for engineering design applications. To further confirm the validity of the numerical solutions, an experimental apparatus was constructed using electric resistance heat to simulate the constant heat flux of the solar source. Water was introduced at the top of this heated vertical surface at various flow rates and under various supplied heat fluxes, and a natural convection channel flow generated between the heated falling film and a parallel, plexiglass surface. Film temperatures and moist air velocity profiles were measured at various streamwise (vertical) locations for comparison with the numerical results. In general, measured film temperatures were 15 to 20 percent lower than the predicted values, but came to within 3 percent of the predictions when experimental uncertainty was incorporated into the numerical inputs. Photographic smoke-wire measurements of the induced moist air velocity were about 20 percent higher than the numerical predictions for small channel gap spacing, and about 50 percent higher for large gap spacing. These trends in the data indicate that a redistribution of the supplied heat flux from the film to the moist air is required to lower predicted film temperatures and raise predicted gas velocities. Physically plausible arguments to explain this redistribution and suggestions for improving the numerical predictions and the experimental measurements are offered.

Buck, Gregory Allen

1990-01-01

117

Modeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal Mass of the Fluid  

E-print Network

source heat pump (GSHP) systems. Thermal load profiles vary significantly from building to building of the system, as the COP of the heat pump varies with entering fluid temperature. Therefore, it is desirableModeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal

118

Vibration Characteristics of a Vertical Round Tube According to Heat Transfer Regimes  

SciTech Connect

This paper presents the results of an experimental work on the effects of boiling heat transfer regimes on the flow-induced vibration (FIV). The experiment has been performed using an electrically heated vertical round tube through which water flows at atmospheric pressure. Vibration characteristics of the heated tube are changed significantly by heat transfer regimes and flow patterns. For single-phase liquid convection, the rod vibrations are negligible. However, on the beginning of subcooled nucleate boiling at tube exit, vibration level becomes very large. As bubble departure occurs at the nucleation site of heated surface, the vibration decreases to saturated boiling region where thermal equilibrium quality becomes 0.0 at tube exit. In saturated boiling region, vibration amplitude increases with exit quality up to a certain maximum value due to the reinforced turbulence then decreases. At liquid film dryout condition, vibration could be regarded as negligible, however, these results cannot be extended to DNB-type CHF mechanism. Frequency analysis results of vibration signals suggested that excitation sources be different with heat transfer regimes. This study would contribute to improve the understanding of the relationship between boiling heat transfer and FIV. (authors)

Yong Ho Lee; Soon Heung Chang [Korea Advanced Institute of Science and Technology, 373-1, Guseung-dong, Yuseong-ku, Daejeon, 305-701 (Korea, Republic of); Won-Pil Baek [Korea Atomic Energy Research Institute, 150, Dukjin-Dong, Yusong-Gu, Taejon 305-353 (Korea, Republic of)

2002-07-01

119

Interfacial shear and waviness effects on laminar film flow heat transfer in vertical tubes  

SciTech Connect

This study presents experimental data for local laminar-film heat transfer with interfacial waviness and shear stress effects, for two film-formation methods: condensation only and condensation on injected films. The results explain differences between correlations commonly used to predict heat transfer through liquid films. Wave evolution is significantly influenced by both the length of longitudinal development and by the film-formation method. This study of condensation inside a vertical tube demonstrates that for small amplitude wavy films, heat transfer enhancement by interfacial shear results primarily from thinning of the film, whereas for films with large disturbance waves, interfacially-induced turbulent enhancement becomes increasingly important. Contrary to the common assumption, when the film is fairly smooth, interfacial shear has little effect on film transition to turbulence.

Kuhn, S.Z.; Peterson, P.F.; Schrock, V.E. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering

1996-12-31

120

Natural convection on a vertical plate in a saturated porous medium with internal heat generation  

NASA Astrophysics Data System (ADS)

The main goal of this paper is to re-exam a class of exact solutions for the two-dimensional free convection boundary layers induced by a heated vertical plate embedded in a saturated porous medium with an exponential decaying heat generation. The temperature distribution of the plate has been assumed to vary as a power of the axial coordinate measured from the leading edge of the plate and subjected to an applied lateral mass flux. The boundary layer equations are solved analytically and numerically using a fifth-order Runge-Kutta scheme coupled with the shooting iteration method. As for the classical problem without internal heat generation, it is proved that multiple (unbounded) solutions arise for any and for any suction/injection parameter. For such solutions, the asymptotic behavior as the similarity variable approaches infinity is determined.

Guedda, M.; Sriti, M.; Achemlal, D.

2014-08-01

121

Non-Darcy mixed convection in a vertical porous channel with asymmetric wall heating  

NASA Astrophysics Data System (ADS)

A numerical study of buoyancy-assisted mixed convection in a vertical porous channel with asymmetric heating at the walls was performed. The Brinkman-Forchheimer-extended Darcy model was used to account for both the inertia and the viscous effects. The evolution of mixed convection in the entrance region was examined in detail. Both uniform wall temperature and uniform wall heat flux conditions were examined for the case when buoyancy effects are assisting the upward flow. Results show that as the Darcy number is decreased while the modified Grashof number and the Reynolds number are kept constant, distortions in the velocity profile result in increased velocities near the walls leading to increased heat transfer.

Hadim, H. A.; Chen, G.

1994-10-01

122

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

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

Onder Ozgener; Arif Hepbasli

2007-01-01

123

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

E-print Network

dimensional calculations of Slab are integrated with one-dimensional heat conduction calculations of EnergyPlus through iteration. According to Bahnfleth [6], ground surface condition is the most significant boundary condition for the floor heat transfer...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...

Andolsun, S.; Culp, C.

2011-01-01

124

GLOBAL WELL-POSEDNESS OF THE 3D PRIMITIVE EQUATIONS WITH PARTIAL VERTICAL TURBULENCE MIXING HEAT DIFFUSION  

E-print Network

­POSEDNESS OF THE 3D PRIMITIVE EQUATIONS WITH PARTIAL VERTICAL TURBULENCE MIXING HEAT DIFFUSION CHONGSHENG CAOGLOBAL WELL-POSEDNESS OF THE 3D PRIMITIVE EQUATIONS WITH PARTIAL VERTICAL TURBULENCE MIXING HEAT­posedness of the 3D Navier­Stokes equations are considered to be among the most challenging mathematical problems

125

Natural convection in a vertical heated tube attached to a thermally insulated chimney of a different diameter  

Microsoft Academic Search

Natural convection is often a convenient and inexpensive mode of heat transfer. It is commonly employed in the cooling of electronic equipment and many other applications. Since the initial work by Bodoia and Osterle (1962) on finite difference solutions of natural convection between vertical isothermal plates, many other researchers have studied natural convection in vertical channels. Specifically Davis and Perona

Y. Asako; H. Nakamura; M. Faghri

1990-01-01

126

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

PubMed

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

Uddin, Ziya; Harmand, Souad

2013-01-01

127

The Sensitivity of Shortwave Radiative Forcing and Heating Rates to the Aerosol Vertical Profile  

NASA Astrophysics Data System (ADS)

We are investigating the sensitivity of the shortwave aerosol radiative forcing and the heating rate profile to the vertical profile of aerosol optical properties (extinction, single-scattering albedo, and asymmetry parameter), solar geometry and surface albedo for clear-sky conditions. Total uncertainties in modeled local diurnally averaged direct radiative forcing (DRF) at the surface and top of the atmosphere (TOA) due to uncertainties in the input parameters mentioned above range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models (RRTM_SW and SBDART) suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties. In this presentation we are assessing the results not only at TOA and the surface but throughout the vertical profile. As inputs, we are using slightly idealized case studies from SAFARI-2000 (Southern Africa), ACE-Asia (Sea of Japan, 2001), ARM Aerosol IOP (Oklahoma, 2003), and RADAGAST (Niger, 2006). These case studies encompass a wide range of aerosols including marine, local and transported smoke, dust, and pollution aerosols. Initial results indicate that the shape of the aerosol extinction profile has very little impact on TOA and surface forcing. However, as long as the aerosol is not purely scattering (i.e single-scattering albedo < 1), the shape of the extinction profile is important for the vertical profiles of forcing and heating rates. In contrast, the shape of the aerosol absorption profile has a slight impact on TOA and surface forcing but is the main driver for the forcing and heating rate profiles. Unfortunately, the vertical profile of aerosol absorption is a quantity that is currently measured with rather large uncertainties only. We also show actual measurements of up and down-welling spectral flux profiles from the 2003 ARM Aerosol IOP and our attempts at deriving heating rate profiles from these.

Schmid, B.; Guan, H.; McComiskey, A.; McFarlane, S.; Kuzmanoski, M.; Pilewskie, P.; Magi, B.

2007-12-01

128

Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D  

SciTech Connect

Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

Hollmann, E. M.; Moyer, R. A. [University of California-San Diego, La Jolla, California 92093 (United States)] [University of California-San Diego, La Jolla, California 92093 (United States); Commaux, N.; Jernigan, T. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; Wesley, J. C. [General Atomics, San Diego, California 92186 (United States)] [General Atomics, San Diego, California 92186 (United States); Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Pitts, R. A.; Sugihara, M. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance (France)] [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance (France); Watkins, J. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

2013-06-15

129

Heat pump R and D at Oak Ridge National Laboratory  

NASA Astrophysics Data System (ADS)

Heat pump system and component performance evaluations at steady state and under frosting conditions are described. A computer model of electric motor driven heat pumps was developed to explore the practical limits of steady-state heating efficiency of conventional air-source heat pumps, and to demonstrate an approach to computer-aided heat pump design techniques. Scoping calculations of alternative heat pump systems, such as aircycle heat pumps and electric motor driven Stirling heat pumps are presented. Computer programs were written to model the expected performance of vertical-pipe ground-coupled heat exchangers, and for the detailed performance analysis of air-to-refrigerant heat exchangers with complex refrigerant circuiting by calculating the performance of each tube of the heat exchanger individually. Seasonal performance factors for air-source heat pumps using hour-by-hour calculations with empirical temperature dependent degradation factors were estimated.

Ellison, R. D.; Creswick, F. A.

130

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

SciTech Connect

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)

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

131

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

E-print Network

within the range presented by Henninger and Witte [17]. In the ground isolated condition, one of the primary reasons for the differences in thermal load estimates of DOE-2 and EnergyPlus programs was the different window solar heat gains calculated.... The ground temperatures calculated by Winkelmann’s (GCW), Slab (GCS) and TRNSYS (GCT) slab-on-grade models were entered into EnergyPlus and the resulting ground coupling loads were compared. At the second step, load components (i.e. wall heat transfer...

Andolsun, S.; Culp, C.

2012-01-01

132

Instability of mixed convection in a vertical porous channel with uniform wall heat flux  

NASA Astrophysics Data System (ADS)

Mixed convection in a vertical plane channel filled with a saturated porous medium is investigated. The boundary planes are considered as subject to symmetric uniform heat fluxes, resulting into a net fluid heating or cooling. Either upflow or downflow conditions are considered, thus exhibiting two distinct regimes: buoyancy-assisted and buoyancy-opposed. A basic stationary and parallel flow directed vertically along the channel is examined. The linear stability of this basic solution is developed through the standard normal-mode analysis. The solution of the eigenvalue problem for neutral stability is carried out numerically for the general oblique modes. An analytical solution is provided for the longitudinal modes, with a horizontal wave vector having a direction parallel to the boundary planes. An asymptotic analytical solution is also allowed for oblique modes with either a vanishingly small Péclet number or a vanishingly small wave number. The longitudinal modes are the most unstable, displaying their parametric domain of instability under buoyancy-opposed regime. In this regime, the longitudinal modes with sufficiently small wave numbers are always unstable. This conclusion suggests that conditions of flow reversal or crossing of parametric singularities, characteristic of the parallel flow solution under buoyancy-opposed regime, are unlikely to be observed in an experiment.

Barletta, A.

2013-08-01

133

Parametric analysis of entropy generation due to laminar developing mixed convection between differentially heated isothermal vertical parallel plates  

Microsoft Academic Search

Purpose – The aim of this article is to present the results of a parametric analysis of the entropy generation due to mixed convection in the entry-developing region between two differentially heated isothermal vertical plates. Design\\/methodology\\/approach – The entropy generation was estimated via a numerical solution of the mass, momentum and energy conservation equations governing the flow and heat transfer

Esmail M. A. Mokheimer

2010-01-01

134

Critical heat flux performance of hypervapotrons proposed for use in the ITER divertor vertical target  

NASA Astrophysics Data System (ADS)

Task T-222 of the International Thermonuclear Experimental Reactor (ITER) program addresses the manufacturing and testing of permanent components for use in the ITER divertor. Thermal-hydraulic and critical heat flux performance of the heat sinks proposed for use in the divertor vertical target are part of subtask T-222.4. As part of this effort, two single channel, medium-scale, bare copper alloy, hypervapotron mock-ups were designed by Sandia National Laboratories and McDonnell Douglas Aerospace (MDA), fabricated at MDA and tested at Sandia' Plasma Materials Test Facility using the EB-1200 electron beam system. The objectives of our effort were to develop the design and manufacturing procedures required for construction of robust HHF components, verify thermal-hydraulic, thermomechanical and CHF performance under ITER relevant conditions, and perform analyses of HHF data to identify design guidelines, failure criteria and possibly modify any applicable CHF correlations. This paper describes the design, fabrication and finite elements modeling of two types of hypervapotrons, a common version already in use at JET and a new attached- fin design. HHF test data on the attached-fin hypervapotron will be used to compare the CHF performance under uniform heating profiles on long heated lengths to that of localized, highly peaked, off-nominal profiles.

Youchison, Dennis L.; Marshall, Theron D.; McDonald, Jimmie M.; Lutz, Thomas J.; Watson, Robert D.; Driemeyer, Daniel E.; Kubik, David L.; Slattery, Kevin T.; Hellwig, Theodore H.

1997-12-01

135

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

SciTech Connect

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)

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

2012-07-01

136

A study of free convection induced by a vertical wavy surface with heat flux in a porous enclosure  

SciTech Connect

Study of natural convection in porous enclosures is of great importance in several scientific and engineering applications such as nuclear waste management, transpiration cooling, building thermal insulators, geothermal power plants, grain storage, and so on. Here, free convection induced by a vertical wavy surface with uniform heat flux in a porous enclosure has been analyzed numerically using the finite element method (FEM). The flow and the convection process in the cavity is found to be sensitive to the flow parameter Rayleigh number (Ra), and geometrical parameters like wave amplitude (a), wave phase ({phi}), and number of waves (N) in the vertical dimension of the cavity. The study reveals that small sinusoidal drifts from the smoothness of a vertical wall with a phase angle of 60{degree} and high frequency enhances the free convection from a vertical wall with uniform heat flux.

Kumar, B.V.R.

2000-04-01

137

Vertical Variations In Heat Flow Inferred From Experiments In Deep Boreholes  

NASA Astrophysics Data System (ADS)

Deep scientific and parametric continental boreholes allow to obtain representative experimental data on combination of the geothermal parameters of the crust - temperature, temperature gradient, rock thermal properties, and, as the result, heat flow density values - which are more reliable compared to the previous data from shallow boreholes. Special advantages of the scientific boreholes include also a possibility for many repeated temperature logging during long time intervals (several years often) after a finish of the drilling that allowed (1) to determine temperatures and temperature gradient values corresponding to thermal equilibrium of the formations studied, (2) to study temporal regularities in temperature and temperature gradient behaviour within different formation layers during the formation recovery process. Scientific boreholes are drilled with numerous coring (often - with continuous coring) that provides the possibility to obtain detailed information on a distribution of rock thermal conductivity along the borehole. As a result, the scientific deep and super-deep boreholes provided the unique possibility for the determination of vertical distributions of the heat flow density that can not be reached normally in other boreholes. Experimental geothermal and petrothermal investigations performed for the super-deep boreholes Kola, Ural, Vorotilovo, Tyumen, Yen-Yakha (all - Russia), Saatly (Azerbaidzhan), and deep scientific and parametric boreholes Kolva, Timano-Pechora, Tyrnyaus, (all - Russia), Krivoy Rog (Ukraine), Muruntau (Uzbekistan), Nordlingen-72 (Germany), Yaxcopoil-1 (Mexico) allowed us to establish the following important peculiarities in geothermal parameters of the crustal blocks studied with scientific deep drilling were established from the investigations: (1) temperature gradient recovery up to undisturbed values occurs essentially faster than it was assumed earlier; (2) a rate of temperature gradient recovery was found to be different for different formation layers; (3) significant variations in rock thermal properties vary significantly along boreholes within several thousands, hundreds and dozens meters as well as along short depth intervals of 0.5-1 m; (4) conductive component of the heat flow density varies up to 70-100% along boreholes often, regular increase in heat flow density within depth intervals of several kilometers is combined with essential local variations, (5) values of a conductive component of the heat flow density established from the measurements in deep and super-deep boreholes exceeds significantly (by 30-100%) and systematically the previous experimental estimates done earlier for shallow boreholes. The mentioned regularities in behaviour of the geothermic parameters were confirmed from new experimental data for the scientific and parametric boreholes Severo-Molokovo, Vysokovo, Yarudeyskaya (Russia), Eyreville (USA) and from the revision of previous experimental geothermic data for the Moscow syneclise (the East European platform) and Ural region. The new results obtained from studying vertical variations in the heat flow density demonstrate a regular essential (30-60%) increase in the conductive component of the heat flow density with a depth within upper depth intervals up to 2000-3000 m. The results show that the determination of heat flow values from averaging the geothermal parameters within long depth intervals can lead to essential underestimation of the crustal heat flow values.

Popov, Y.; Romushkevich, R.; Gorobtsov, D.; Korobkov, D.

2012-04-01

138

Nonlinear dynamics between two differentially heated vertical plates in the presence of stratification  

NASA Astrophysics Data System (ADS)

We consider the numerical simulation of the flow between infinite, differentially heated vertical plates with positive stratification. We use a two-dimensional Boussinesq approximation, with periodic boundary conditions in the vertical direction. The relative stratification parameter {?=(1/4Ra S)^{1/4}} , where Ra is the Rayleigh number and S the adimensional stratification, is kept constant and equal to 8. The Prandtl number is 0.71. We derive a complex Ginzburg-Landau equation from the equations of motion. Coefficients are computed analytically, but we find that the domain of validity of these coefficients is small and rely on the numerical simulation to adjust the coefficients over a wider range of Rayleigh numbers. We show that the Ginzburg-Landau equation is able to accurately predict the characteristics of the periodic solution at moderate Rayleigh numbers. Above the primary bifurcation at Ra = 1.63 × 105, the Ginzburg-Landau model is found to be Benjamin-Feir unstable and to be characterized by modulated traveling waves and phase-defect chaos, which is supported by evidence from the DNS. As the Rayleigh number is increased beyond Ra = 2.7 × 105, nonlinearities become strong and the flow is characterized by cnoidal waves.

Podvin, Bérengère; Le Quéré, Patrick

2013-02-01

139

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

SciTech Connect

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.

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

2010-03-31

140

Vertical Profiles of Latent Heating in TRMM: Validation and Assimilation in the GEOS Data Assimilation System. [Year 2001 Project Report  

NASA Technical Reports Server (NTRS)

I have derived the vertical profiles of apparent heating Q and Q2 by using 3-hourly balloon sounding data from the ARM SGP sounding array for three IOPs in 2000. These IOPs cover the periods from 3/1 to 3/22, from 9/25 to 10/8, and from 11/27 to 12/22. These heating profiles will be collocated with the TRMM heating profiles for validation studies once the TRMM profiles become available to the investigators. I have also produced the objective analyses of Q1, Q2 and forcing fields for the international GCSS Case 3 Intercomparison project. The GSFC CRM participated in study, based on which TRMM heating profiles are derived. I have also studied to assimilate the vertical heating profile by constraining the cloud-base mass flux in the cumulus convection scheme using the CCM3. I first derive the vertical heating profile for each convective plume of unit cloud-base mass flux. The observed heating profile form ARM is then de-convoluted to derive the cloud base mass fluxes of all individual plumes. These fluxes are compared with those derived from the quasi-equilibrium hypothesis. They are shown to improve many other aspects of the model behavior.

Zhang, Ming-Hua

2001-01-01

141

Vertical ocean heat fluxes beneath Linear Kinematic Features: a potential mechanism for rapid sea-ice decline in the Arctic  

NASA Astrophysics Data System (ADS)

The Cold Halocline Layer is known to provide a strong barrier to vertical exchange in the surface Arctic ocean. We show modelling evidence, supported by observations, for strong Ekman pumping velocities beneath active leads, where discontinuity in the sea-ice drifts and the surface ice-ocean stresses momentum transfer are present. On Figure 1 shown an example of the lead opening. The anomalous vertical velocities beneath the leads extend hundreds of meters below the surface, well into the Atlantic Layer, and bring up large amount of ocean heat (of the order of hundred's of W/m2) into the mixed layer (see Figure 2 - cross section of the lead from Figure 1). We use a high resolution (4 km) general circulation model with a good representation of the CHL and NSTM (the MITgcm). Results show vertical ocean heat fluxes in winter of approximately 3 W/m2 when averaged over the ice-covered Arctic ocean which is equivalent to 15 cm sea-ice melt during a year. We suggest that this process is important in controlling the Arctic sea-ice mass balance and a potentially important player in the recent sea-ice decline - one that is not represented in lower-resolution global climate models. In a future climate with thinner and more mobile pack ice, this contribution from the ocean will only amplify. a) - Sea-ice shear strain rate, day-1 b) - vertical advective ocean heat flux, W/m2 at 40 m depth, c) - sea-ice stress curl, s-1 and d) - sea-ice divergence, s-1. Vertical section across the sea-ice lead of vertical velocity in m/day (a), temperature in oC (b) and vertical advective ocean heat flux in W/m2 (c).

Slavin, A.; Tremblay, B.; Straub, D.

2013-12-01

142

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

143

HEAT TRANSFER MEASUREMENTS OF MIXED CONVECTION FOR UPWARD AND DOWNWARD LAMINAR FLOWS INSIDE A VERTICAL CIRCULAR CYLINDER  

Microsoft Academic Search

Mixed convection heat transfer inside a vertical circular cylinder has been experimentally studied for upward and downward flows for hydrodynamically fully developed and thermally developing laminar air flow under constant wall heat flux boundary conditions for Reynolds number range from 400–1600 and the Grashof number range from 1.1 × 10–7.4 × 10. The effects of the cylinder inclination angle and

H. A. Mohammed; Y. K. Salman

2008-01-01

144

New data on two-phase two-component heat transfer and hydrodynamics in a vertical tube  

Microsoft Academic Search

In forced-convective two-phase, two component (gas-liquid) flow, experimental data for mean heat-transfer coefficients, pressure drop and flow patterns were taken simultaneously for the flow in a 1.17-cm i.d. electrically heated vertical tube using three liquids: water, glycerine and water and silicone liquid with air as the gas phase. The combination of silicone liquid and the glycerine and water solution provided

K. S. Rezkallah; G. E. Sims

1987-01-01

145

Open-cycle absorption solar cooling: Natural convection heat and mass transfer from falling films in vertical channels  

NASA Astrophysics Data System (ADS)

In the design of solar collector/regenerators for use in open cycle absorption refrigeration (OCAR) units, the problem of predicting evaporation rates and solution temperatures is of paramount importance in determining overall cycle performance. The governing equations for natural convection flow in a vertical channel bounded by a heated falling film (simulating a glazed collector/regenerator) were solved using several different finite difference techniques. The numerical results were validated against existing experimental and numerical results for simplified boundary conditions. The appropriate nondimensionalization for the falling film boundary condition was established, ostensibly for the first time, and a parametric study for an air-water vapor mixture has been presented. Curve fits to the numerical results were determined for engineering design applications. To further confirm the validity of the numerical solutions, an experimental apparatus was constructed using electric resistance heat to simulate the constant heat flux of the solar source. Water was introduced at the top of this heated vertical surface at various flow rates and under various supplied heat fluxes, and a natural convection channel flow generated between the heated falling film and a parallel, plexiglas surface. Film temperatures and moist air velocity profiles were measured at various streamwise (vertical) locations for comparison with the numerical results.

Buck, G. A.; Wood, B. D.

1992-06-01

146

Characteristics of vortex flow in a low speed air jet impinging onto a heated disk in a vertical cylindrical chamber  

Microsoft Academic Search

An experiment combining flow visualization and transient temperature measurement is carried out to investigate the characteristics of the mixed convective vortex flow resulting from a low speed air jet impinging onto a heated horizontal circular disk confined in a vertical adiabatic cylindrical chamber. Attention is focused on the conditions leading to the onset of the inertia and buoyancy driven vortex

J. C. Hsieh; T. C. Cheng; T. F. Lin

2003-01-01

147

Experimental and empirical study of steam condensation heat transfer with a noncondensable gas in a small-diameter vertical tube  

Microsoft Academic Search

An experimental study was performed to investigate local condensation heat transfer coefficients in the presence of a noncondensable gas inside a vertical tube. The data obtained from pure steam and steam\\/nitrogen mixture condensation experiments were compared to study the effects of noncondensable nitrogen gas on the annular film condensation phenomena. The condenser tube had a relatively small inner diameter of

Kwon-Yeong Lee; Moo Hwan Kim

2008-01-01

148

Modeling of Heat Transfer in Geothermal Heat Exchangers  

E-print Network

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...

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

2006-01-01

149

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

NASA Astrophysics Data System (ADS)

Fermilab Vertical Test Stand-1 (VTS-1) has been in operation since 2007 for testing superconducting radio frequency (SCRF) cavities at 2 K. This test stand includes a heat exchanger consisting of a single layer; helically wound finned tube, upstream of the J-T valve. A finite difference thermal model has been developed in Engineering Equation Solver (EES) to study the thermal performance of this heat exchanger during refilling of the test stand. The model can predict heat exchanger performance under various other operating conditions and is therefore useful as a design tool for similar heat exchangers in other facilities. The present paper discusses the different operational modes of this heat exchanger and its thermal characteristics under these operational modes. Results of this model have been compared with experimental data gathered from the VTS-1 heat exchanger, and they are in good agreement with the present model.

Gupta, Prabhat Kumar; Rabehl, Roger

2014-07-01

150

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

E-print Network

instrumented ASHP vanad, 1990) indicated temperature differences of 10.6 and 1 1.1 OC at outdoor temperatures of 27.8 and 3S°C. respectively. Thus, a GCHP whose EWT is 5 to 8.3OC higher than the outdoor air temperature may still produce the same... instrumented ASHP vanad, 1990) indicated temperature differences of 10.6 and 1 1.1 OC at outdoor temperatures of 27.8 and 3S°C. respectively. Thus, a GCHP whose EWT is 5 to 8.3OC higher than the outdoor air temperature may still produce the same...

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

1994-01-01

151

Transition to chaos of natural convection between two infinite differentially heated vertical plates.  

PubMed

Natural convection of air between two infinite vertical differentially heated plates is studied analytically in two dimensions (2D) and numerically in two and three dimensions (3D) for Rayleigh numbers Ra up to 3 times the critical value Ra(c)=5708. The first instability is a supercritical circle pitchfork bifurcation leading to steady 2D corotating rolls. A Ginzburg-Landau equation is derived analytically for the flow around this first bifurcation and compared with results from direct numerical simulation (DNS). In two dimensions, DNS shows that the rolls become unstable via a Hopf bifurcation. As Ra is further increased, the flow becomes quasiperiodic, and then temporally chaotic for a limited range of Rayleigh numbers, beyond which the flow returns to a steady state through a spatial modulation instability. In three dimensions, the rolls instead undergo another pitchfork bifurcation to 3D structures, which consist of transverse rolls connected by counter-rotating vorticity braids. The flow then becomes time dependent through a Hopf bifurcation, as exchanges of energy occur between the rolls and the braids. Chaotic behavior subsequently occurs through two competing mechanisms: a sequence of period-doubling bifurcations leading to intermittency or a spatial pattern modulation reminiscent of the Eckhaus instability. PMID:24032927

Gao, Zhenlan; Sergent, Anne; Podvin, Berengere; Xin, Shihe; Le Quéré, Patrick; Tuckerman, Laurette S

2013-08-01

152

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

PubMed

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

Cai, Wenli; Su, Ning; Liu, Xiangdong

2014-01-01

153

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

NASA Astrophysics Data System (ADS)

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.

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

154

Unsteady Convection Flow and Heat Transfer over a Vertical Stretching Surface  

PubMed Central

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

Cai, Wenli; Su, Ning; Liu, Xiangdong

2014-01-01

155

Measuring the electrical properties of soil using a calibrated ground-coupled GPR system  

USGS Publications Warehouse

Traditional methods for estimating vadose zone soil properties using ground penetrating radar (GPR) include measuring travel time, fitting diffraction hyperbolae, and other methods exploiting geometry. Additional processing techniques for estimating soil properties are possible with properly calibrated GPR systems. Such calibration using ground-coupled antennas must account for the effects of the shallow soil on the antenna's response, because changing soil properties result in a changing antenna response. A prototype GPR system using ground-coupled antennas was calibrated using laboratory measurements and numerical simulations of the GPR components. Two methods for estimating subsurface properties that utilize the calibrated response were developed. First, a new nonlinear inversion algorithm to estimate shallow soil properties under ground-coupled antennas was evaluated. Tests with synthetic data showed that the inversion algorithm is well behaved across the allowed range of soil properties. A preliminary field test gave encouraging results, with estimated soil property uncertainties (????) of ??1.9 and ??4.4 mS/m for the relative dielectric permittivity and the electrical conductivity, respectively. Next, a deconvolution method for estimating the properties of subsurface reflectors with known shapes (e.g., pipes or planar interfaces) was developed. This method uses scattering matrices to account for the response of subsurface reflectors. The deconvolution method was evaluated for use with noisy data using synthetic data. Results indicate that the deconvolution method requires reflected waves with a signal/noise ratio of about 10:1 or greater. When applied to field data with a signal/noise ratio of 2:1, the method was able to estimate the reflection coefficient and relative permittivity, but the large uncertainty in this estimate precluded inversion for conductivity. ?? Soil Science Society of America.

Oden, C.P.; Olhoeft, G.R.; Wright, D.L.; Powers, M.H.

2008-01-01

156

An experimental study on flow patterns and heat transfer characteristics during cryogenic chilldown in a vertical pipe  

NASA Astrophysics Data System (ADS)

In the present paper, the experimental results of a cryogenic chilldown process are reported. The physical phenomena involve unsteady two-phase vapor-liquid flow and intense boiling heat transfer of the cryogenic fluid that is coupled with the transient heat conduction inside pipe walls. The objective for the present study is to compare the chilldown rates and flow patterns between the upward flow and downward flow in a vertical pipe. Liquid nitrogen is employed as the working fluid and the test section is a vertical straight segment of a Pyrex glass pipe with an inner diameter of 8 mm. The effects of mass flow rate on the flow patterns, heat transfer characteristics and interface movement were determined through experiments performed under several different mass flow rates. Through flow visualization, measurement and analysis on the flow patterns and temperature variations, a physical explanation of the vertical chilldown is given. By observing the process and analyzing the results, it is concluded that pipe chilldown in a vertical flow is similar to that in microgravity to some extent.

Hu, Hong; Chung, Jacob N.; Amber, Samuel H.

2012-04-01

157

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

SciTech Connect

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)

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

158

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

Microsoft Academic Search

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

Kadir Bakirci; Omer Ozyurt; Kemal Comakli; Omer Comakli

2011-01-01

159

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

NASA Technical Reports Server (NTRS)

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.

Kassemi, Siavash A.

1988-01-01

160

Analysis of Vertical Turbulent Heat Flux Limit in Stable Conditions with a Local Equilibrium, Turbulence Closure Model  

NASA Astrophysics Data System (ADS)

Assuming that the vertical turbulent heat flux vanishes at extremely stable conditions, one should expect its maximal absolute value to occur somewhere at moderate stability, between a neutral and extremely stable equilibrium. Consequently, in some situations duality of solutions may be encountered (e.g. two different values of temperature difference associated with the same values of heat flux and wind speed). A quantitative analysis of this feature with a local equilibrium Reynolds-stress model is presented. The fixed-wind / fixed-shear maximum has been identified both in the bulk and in single-point flux-gradient relationships (that is, in the vertical temperature gradient and wind-shear parameter domain). The value of the Richardson number corresponding to this maximum is derived from the model equations. To study the possible feedback in strongly stable conditions, weak and intense cooling scenarios have been simulated with a one-dimensional numerical, high-resolution atmospheric boundary-layer model. Despite the rapid cooling, flow decoupling at the surface has not been observed; instead, a stability-limited heat flux is maintained, with a gradual increase of the Richardson number towards the top of the turbulent layer, with some signs of oscillatory behaviour at intermediate heights. Vertical changes of wind shear and the Brunt-Väisälä frequency display a remarkably non-monotonic character, with some signs of a gradually developing instability.

?obocki, Lech

2013-09-01

161

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

PubMed

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

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

2012-01-01

162

Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

163

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)

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.

Eckert, E R G; Diaguila, A J

1952-01-01

164

Numerical modelling the unsteady process of closed rectangular area radiant heating in conjugate formulation with accounting energy distribution along horizontal and vertical enclosure structures  

NASA Astrophysics Data System (ADS)

Mathematical modelling of unsteady convective-conductive heat exchange in premises, heated by infrared radiant heater is passed. Heat flux density from infrared radiant heater was calculated accounting energy distribution along horizontal and vertical building envelope. Comparison between zonal method and Lambert's law radiant energy distribution was done.

Nee, A. E.

2014-08-01

165

Experimental investigation on heat transfer and frictional characteristics of vertical upward rifled tube in supercritical CFB boiler  

SciTech Connect

Water wall design is a key issue for supercritical Circulating Fluidized Bed (CFB) boiler. On account of the good heat transfer performance, rifled tube is applied in the water wall design of a 600 MW supercritical CFB boiler in China. In order to investigate the heat transfer and frictional characteristics of the rifled tube with vertical upward flow, an in-depth experiment was conducted in the range of pressure from 12 to 30 MPa, mass flux from 230 to 1200 kg/(m{sup 2} s), and inner wall heat flux from 130 to 720 kW/m{sup 2}. The wall temperature distribution and pressure drop in the rifled tube were obtained in the experiment. The normal, enhanced and deteriorated heat transfer characteristics were also captured. In this paper, the effects of pressure, inner wall heat flux and mass flux on heat transfer characteristics are analyzed, the heat transfer mechanism and the frictional resistance performance are discussed, and the corresponding empirical correlations are presented. The experimental results show that the rifled tube can effectively prevent the occurrence of departure from nucleate boiling (DNB) and keep the tube wall temperature in a permissible range under the operating condition of supercritical CFB boiler. (author)

Yang, Dong; Pan, Jie; Zhu, Xiaojing; Bi, Qincheng; Chen, Tingkuan [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China); Zhou, Chenn Q. [Department of Mechanical Engineering, Purdue University Calumet, Hammond, IN 46323 (United States)

2011-02-15

166

Equipment for the emplacement of heat-producing waste in long horizontal boreholes. [Horizontal vs vertical emplacement  

SciTech Connect

Emplacement of heat-producing waste in long horizontal holes may offer several technical and economic advantages over shallow vertical hole emplacement. Less of the host rock suffers damage as a result of drift construction; the heat from the waste can be isolated from the access drifts for long periods of time; and the amount of rock which must be excavated is much less than in traditional disposal scenarios. One of the major reasons that has been used to reject the long hole concept in the past and adhere to the shallow vertical hole concept is the equipment required to drill the holes and to emplace and retrieve the waste. Such equipment does not currently exist. It clearly is more difficult to drill a 600 to 1000 foot horizontal hole, possibly 3 to 4 feet in diameter, and place a canister of waste at the end of it than to drill a 30 foot vertical hole and lower the waste to the bottom. A liner, for emplacement hole stabilization, appears to be feasible by adapting existing technology for concrete slip forming or jacking in a steel liner. The conceptual design of the equipment to drill long horizontal holes, emplace waste and retrieve waste will be discussed. Various options in concept will be presented as well as their advantages and disadvantages. The operating scenario of the selected concept will be described as well as solutions to potential problems encountered.

Young, K.D.; Scully, L.W.; Fisk, A.; deBakker, P.; Friant, J.; Anderson, A.

1983-01-01

167

Seismic-geodynamic constraints on three-dimensional structure, vertical flow, and heat transfer in the mantle  

USGS Publications Warehouse

Joint inversions of seismic and geodynamic data are carried out in which we simultaneously constrain global-scale seismic heterogeneity in the mantle as well as the amplitude of vertical mantle flow across the 670 km seismic discontinuity. These inversions reveal the existence of a family of three-dimensional (3-D) mantle models that satisfy the data while at the same time yielding predictions of layered mantle flow. The new 3-D mantle models we obtain demonstrate that the buoyancy forces due to the undulations of the 670 km phase-change boundary strongly inhibit the vertical flow between the upper and lower mantle. The strong stabilizing effect of the 670 km topography also has an important impact on the predicted dynamic topography of the Earth's solid surface and on the surface gravity anomalies. The new 3-D models that predict strongly or partially layered mantle flow provide essentially identical fits to the global seismic data as previous models that have, until now, predicted only whole-mantle flow. The convective vertical transport of heat across the mantle predicted on the basis of the new 3-D models shows that the heat flow is a minimum at 1000 km depth. This suggests the presence at this depth of a globally defined horizon across which the pattern of lateral heterogeneity changes rapidly. Copyright 1997 by the American Geophysical Union.

Forte, A. M.; Woodward, R. L.

1997-01-01

168

Flow and heat transfer characteristics of laminar mixed convection of water with sub-millimeter bubbles in a vertical channel  

NASA Astrophysics Data System (ADS)

Laminar mixed-convection heat transfer is widely seen in compact heat exchangers. Injection of sub-millimeter bubbles is considered as one of the efficient techniques for enhancing laminar mixed-convection heat transfer for liquids. However, the effects of sub-millimeter-bubble injection on the laminar mixed-convection heat transfer are poorly understood. In this study, we experimentally investigate flow and heat transfer characteristics of the laminar mixed-convection of water with sub-millimeter bubbles in a vertical channel. The thermocouples and a PTV (Particle Tracking Velocimetry) technique are used for the temperature and velocity measurements, respectively. Tap water is used for working fluid and hydrogen bubbles generated by electrolysis of water are used as the sub-millimeter bubbles. The Reynolds number of the main flow ranges from 100 to 150. Our results show that the ratio of the heat transfer coefficient with sub-millimeter-bubble injection to that without injection decreases as the Reynolds number increases. It is found from the liquid velocity measurements that this decrease is mainly due to a decrease in the "bubble advection effect".

Kitagawa, A.; Kimura, K.; Endo, H.; Hagiwara, Y.

2009-02-01

169

Evaporation heat transfer and friction characteristics of R-134a flowing downward in a vertical corrugated tube  

SciTech Connect

Differently from most previous studies, the heat transfer and friction characteristics of the pure refrigerant HFC-134a during evaporation inside a vertical corrugated tube are experimentally investigated. The double tube test sections are 0.5 m long with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tubes are one smooth tube and two corrugated tubes, which are constructed from smooth copper tube of 8.7 mm inner diameter. The test runs are performed at evaporating temperatures of 10, 15, and 20 C, heat fluxes of 20, 25, and 30 kW/m{sup 2}, and mass fluxes of 200, 300, and 400 kg/m{sup 2} s. The quality of the refrigerant in the test section is calculated using the temperature and pressure obtained from the experiment. The pressure drop across the test section is measured directly by a differential pressure transducer. The effects of heat flux, mass flux, and evaporation temperature on the heat transfer coefficient and two-phase friction factor are also discussed. It is found that the percentage increases of the heat transfer coefficient and the two-phase friction factor of the corrugated tubes compared with those of the smooth tube are approximately 0-10% and 70-140%, respectively. (author)

Aroonrat, Kanit; Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab. (FUTURE), Department of Mechanical Engineering, King Mongkut's University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)

2011-01-15

170

Experimental Study on Heat Transfer of Single-Phase Flow and Boiling Two-Phase Flow in Vertical Narrow Annuli  

SciTech Connect

Water single-phase and nucleate boiling heat transfer were experimentally investigated in vertical annuli with narrow gaps. The experimental data about water single-phase flow and boiling two-phase flow heat transfer in narrow annular channel were accumulated by two test sections with the narrow gaps of 1.0 mm and 1.5 mm. Empirical correlations to predict the heat transfer of the single-phase flow and boiling two-phase flow in the narrow annular channel were obtained, which were arranged in the forms of the Dittus-Boelter for heat transfer coefficients in a single-phase flow and the Jens-Lottes formula for a boiling two-phase flow in normal tubes, respectively. The mechanism of the difference between the normal channel and narrow annular channel were also explored. From experimental results, it was found that the turbulent heat transfer coefficients in narrow gaps are nearly the same to the normal channel in the experimental range, and the transition Reynolds number from a laminar flow to a turbulent flow in narrow annuli was much lower than that in normal channel, whereas the boiling heat transfer in narrow annular gap was greatly enhanced compared with the normal channel. (authors)

Suizheng Qiu; Guanghui Su; Dounan Jia [Xi'an Jiaotong University, No.28, Xianning West Road, Xi'an, Shaanxi, 710049 (China); Minoru Takahashi [Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152 (Japan)

2002-07-01

171

Estimates of vertical heat flux and stratification from Southern Georges Bank, interannual variability, 1985 1995  

NASA Astrophysics Data System (ADS)

Interannual variability (IAV) of net vertical heat flux ( Q), potential energy anomaly or "stratification index" ( V) and date of onset for water column stratification were studied using five-day averaged model output over an 11 yr (1985-1995) period for three depth zones which span water depths from less than 60 to 100 m on southern Georges Bank. Comparison between five-day averaged model Q estimates from this study and Q measurements from US-GLOBEC mooring ST1 during winter-summer 1995 shows that nearly all of the difference between uncalibrated model estimates and calibrated ST1 measurements is attributable to the difference between the sum of the latent, sensible and long-wave components ( Qe+ Qs+ Qlw) from each data set. Furthermore, there is virtually no IAV in residual five-day averaged Qe+ Qs+ Qlw values relative to the long-term (1985-1995) mean seasonal cycle, suggesting strongly that the calibration of model Q estimates using measurements from mooring ST1 during 1995 may be applied to other years (1985-1994). Calibrated long-term (1985-1995) monthly mean Q values from this study show a similar seasonal cycle to climatological values determined from ship-of-opportunity data. However, values from this study are higher relative to the ship-of-opportunity long-term monthly mean climatology, with largest differences occurring during winter. IAV of monthly mean Q for zones 1-3 on southern Georges Bank is significant with the magnitude of residuals increasing from zones 1 to 3. Long-term (1985-1995) monthly mean model-derived V computed for zones 1-3 shows zone 1 (<60 m depth) remaining well-mixed throughout the year with no stratification development and therefore no detectable IAV for V. However, within zone 2 (60-80 m depth) and zone 3 (80-100 m depth) significant permanent stratification begins to develop during May and April, respectively, increasing almost linearly from May-July and reaching a maximum during July and August, respectively. IAV of V is large for zones 2 and 3 with typical standard deviations of 1000-5000 J m -2 occurring from late-spring-summer with the largest coefficient of variation during spring and fall. Results from linear regression for zones 2-3 show that IAV of V is controlled largely by IAV of Q, explaining up to ˜80% of the variance, with IAV of wind mixing being of secondary importance. Results from model-derived five-day averaged V show that temporary or "transient" stratification nearly always occurs in early-May and mid-April for zones 2 and 3, respectively, over the 11 yr study period and is associated with reduced tidal stirring during periods of neap tide. The mean date of first transient stratification for zone 3 coincides with the historical maximum abundance of early-stage (<6 mm) cod larvae and copepod nauplii for Georges Bank. In addition, the historical maximum abundance of haddock larvae occurs on Georges Bank at the same time that permanent or "seasonal" stratification is established in zone 3.

Bisagni, J. J.

2000-02-01

172

Freezing heat transfer in water-saturated porous media in a vertical rectangular vessel  

Microsoft Academic Search

Numerical and experimental study is performed for the freezing of water-saturated porous media in a vertical rectangular vessel. The governing equations are solved by using a variable transformation and employing a finite difference scheme. The SOR method is utilized to solve numerically the equations. Different size and types of spherical beads are used as the porous media. The temperature of

A. Sasaki; S. Aiba; S. Fukusako

1992-01-01

173

Three dimensional free convection flow and heat transfer along a porous vertical plate  

Microsoft Academic Search

The free convection flow along a vertical porous plate with transverse sinusoidal suction velocity distribution is investigated. Due to this type of suction velocity at the plate the flow becomes three dimensional one. For the asymptotic flow condition, the wall shear stress in the direction of main flow for different values of buoyancy parameter G is obtained. For G=0, the

P. Singh; V. P. Sharma; U. N. Misra

1978-01-01

174

Forced convective flow and heat transfer of upward cocurrent air-water slug flow in vertical plain and swirl tubes  

SciTech Connect

This experimental study comparatively examined the two-phase flow structures, pressured drops and heat transfer performances for the cocurrent air-water slug flows in the vertical tubes with and without the spiky twisted tape insert. The two-phase flow structures in the plain and swirl tubes were imaged using the computerized high frame-rate videography with the Taylor bubble velocity measured. Superficial liquid Reynolds number (Re{sub L}) and air-to-water mass flow ratio (AW), which were respectively in the ranges of 4000-10000 and 0.003-0.02 were selected as the controlling parameters to specify the flow condition and derive the heat transfer correlations. Tube-wise averaged void fraction and Taylor bubble velocity were well correlated by the modified drift flux models for both plain and swirl tubes at the slug flow condition. A set of selected data obtained from the plain and swirl tubes was comparatively examined to highlight the impacts of the spiky twisted tape on the air-water interfacial structure and the pressure drop and heat transfer performances. Empirical heat transfer correlations that permitted the evaluation of individual and interdependent Re{sub L} and AW impacts on heat transfer in the developed flow regions of the plain and swirl tubes at the slug flow condition were derived. (author)

Chang, Shyy Woei [Thermal Fluids Laboratory, National Kaohsiung Marine University, No. 142, Haijhuan Road, Nanzih District, Kaohsiung City 81143 (China); Yang, Tsun Lirng [Department of Marine Engineering, National Kaohsiung Marine University, No. 142, Haijhuan Road, Nanzih District, Kaohsiung City 81143 (China)

2009-10-15

175

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

Microsoft Academic Search

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

Arif Hepbasli; Ozay Akdemir; Ebru Hancioglu

2003-01-01

176

Magnetohydrodynamic peristaltic flow of a hyperbolic tangent fluid in a vertical asymmetric channel with heat transfer  

Microsoft Academic Search

In the present paper we discuss the magnetohydrodynamic (MHD) peristaltic flow of a hyperbolic tangent fluid model in a vertical\\u000a asymmetric channel under a zero Reynolds number and long wavelength approximation. Exact solution of the temperature equation\\u000a in the absence of dissipation term has been computed and the analytical expression for stream function and axial pressure\\u000a gradient are established. The

Sohail Nadeem; Safia Akram

2011-01-01

177

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

NASA Astrophysics Data System (ADS)

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.

Burmistrova, O. A.

2014-05-01

178

Vertical Mass, Momentum, Moisture, and Heat Fluxes in Hurricanes above 10 km during CAMEX-3 and CAMEX-4  

NASA Technical Reports Server (NTRS)

The third and fourth NASA Convection and Moisture Experiments (CAMEX-3 and CAMEX-4) during the Atlantic hurricane seasons of 1998 and 2001, respectively, have yielded comprehensive multi-aircraft datasets using, both remote and in-situ instrumentation. Among these are high-frequency in-situ measurements of vertical wind, horizontal wind, temperature, and water vapor, made from NASA's DC-8 aircraft in the upper portions of the hurricane (typically above 10 km). Wind and temperature measurements were made at 20 hz by the NASA/Ames Meteorological Measurement System, while water vapor was measured at 1 hz by the NASA/JPL Laser Hygrometer. Fluxes of heat, momentum, and moisture at these levels are important, since modeling studies have shown that ice processes, which are dominant at temperatures below -40C (where the DC-8 flies) are important for hurricane intensification. Also, there are indications from satellite studies that latent heat release at DC-8 levels is significant, perhaps a third of those in the mid-troposphere. Preliminary results show that typical updrafts in the eyewall region are comparable to or higher than previous observations of tropical convection, with several instances of updraft magnitudes of 15 meters per second (the maximum observed was 21 meters per second). They also show significant supersaturations (10-20% or more) in the updrafts, which would enhance the latent heat release at the upper levels of the hurricane. This paper will examine the magnitude and distribution of small and mesoscale vertical fluxes of mass, momentum, moisture, and heat. The goal is to examine the role of these fluxes in the overall budgets of the respective quantities in the upper portions of the hurricane.

Pfister, Leonhard; Bui, Paul; Herman, Robert; Dean-Day, Jon; Hipskind, R. Stephen (Technical Monitor)

2002-01-01

179

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

NASA Astrophysics Data System (ADS)

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)

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

2012-04-01

180

Augmentation of condensation heat transfer with electrohydrodynamics on vertical enhanced tubes  

E-print Network

In a condenser the thickness of the liquid condensate film covering the cooled surface constitutes a resistance to the heat transfer. By establishing a non uniform electric field in the vicinity of the condensation surface the extraction of liquid...

Motte, Edouard

2012-06-07

181

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

E-print Network

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 ...

Lee, Jeongik

2005-01-01

182

Interaction of surface radiation with conjugate mixed convection from a vertical channel with multiple discrete heat sources  

NASA Astrophysics Data System (ADS)

Important results of a numerical study performed on combined conduction-mixed convection-surface radiation from a vertical channel equipped with three identical flush-mounted discrete heat sources in its left wall are provided here. The channel has walls of identical height with the spacing varied by varying its aspect ratio (AR). The cooling medium is air that is considered to be radiatively transparent. The heat generated in the channel gets conducted along its walls before getting dissipated by mixed convection and radiation. The governing equations for fluid flow and heat transfer are considered without boundary layer approximations and are transformed into vorticity-stream function form and are later normalized. The resulting equations are solved, along with relevant boundary conditions, making use of the finite volume method. The computer code written for the purpose is validated both for fluid flow and heat transfer results with those available in the literature. Detailed parametric studies have been performed and the effects of modified Richardson number, surface emissivity, thermal conductivity and AR on various pertinent results have been looked into. The significance of radiation in various regimes of mixed convection has been elucidated. The relative contributions of mixed convection and radiation in carrying the mandated cooling load have been thoroughly explored.

Londhe, Shrikant D.; Gururaja Rao, C.

2014-09-01

183

Study on heat transfer characteristic of ethanol-water mixture condensation on a vertical micro-tube  

NASA Astrophysics Data System (ADS)

In present experiment, the vapor mixture with different velocities (2m?s-1, 4m?s-1) and different ethanol mass fraction (0.5%, 1%, 2%, 5%, 10%, 20%, 50%) flew through vertical micro-tube and condensed on the outer tube surface at pressure 31.16kPa, 47.36kPa. The condensation modes were observed by CCD camera, and the characteristics of the heat transfer coefficients versus the vapor-to-surface temperature differences for different experimental conditions were obtained. The condensation heat transfer coefficients of vapor mixture decrease with the vapor concentration increasing. The maximum peak value of heat transfer coefficients, up to 39 kW?m-2?K1, which was about 3-4 times greater than that of steam, appeared when the ethanol mass fraction was 2%. A heat transfer coefficient correlation including the effects of all the tested parameters is proposed by using the multiple linear least squares method based on the experimental data. The calculated values agreed well with the experimental data and the deviations between them were from -20% to 20%.

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

2013-07-01

184

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

PubMed Central

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

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

2013-01-01

185

MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.  

PubMed

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 x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x 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

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

2013-01-01

186

Using sea ice to measure vertical heat flux in the ocean  

Microsoft Academic Search

Results of an experiment performed at drifting ice station FRAM I in the Arctic Ocean northwest of Spitzbergen during March-May 1979 indicate that sensible heat flux from the ocean to the ice cover was less than 2 W m2. The estimate is based on measurements of temperature gradient, growth rate and salinity of young sea ice. Uncertainty in the magnitude

Miles G. McPhee; Norbert Untersteiner

1982-01-01

187

Vertical Concentric Tube Ground Couoled Heat Exchangers V. C. Mei and S. K. Fischer*  

E-print Network

the effects of variations in heat-exchanger length, diame- ter, flow rate, and thermal conductivityNTRODUCTION The realization that conventional energy resources are limited urges us to increase our efforts to use non-renewable sources more efficiently. One of several alternatives available is to search for energy saving

Oak Ridge National Laboratory

188

Thermosolutal convection from a discrete heat and solute source in a vertical porous annulus  

E-print Network

are petrochemical pro- cesses, the food industry, grain storage installations, fuel cells, crystal growth applied- ically investigated with the aim to understand the effects of a discrete source of heat and solute a portion of the inner wall, while the outer wall is maintained at uniform temperature and concentration

Lopez, John M.

189

Vertical variation in heat flow on the Kola Peninsula: palaeoclimate or fluid flow?  

NASA Astrophysics Data System (ADS)

Following earlier studies, we present forward and inverse simulations of heat and fluid transport of the upper crust using a local 3-D model of the Kola area. We provide best estimates for palaeotemperatures and permeabilities, their errors and their dependencies. Our results allow discriminating between the two mentioned processes to a certain extent, partly resolving the non-uniqueness of the problem. We find clear indications for a significant contribution of advective heat transport, which, in turn, imply only slightly lower ground surface temperatures during the last glacial maximum relative to the present value. These findings are consistent with the general background knowledge of (i) the fracture zones and the corresponding fluid movements in the bedrock and (ii) the glacial history of the Kola area.

Vogt, C.; Mottaghy, D.; Rath, V.; Marquart, G.; Dijkshoorn, L.; Wolf, A.; Clauser, C.

2014-11-01

190

Finite line-source model for borehole heat exchangers: effect of vertical temperature variations  

Microsoft Academic Search

A solution to the three-dimensional finite line-source (FLS) model for borehole heat exchangers (BHEs) that takes into account the prevailing geothermal gradient and allows arbitrary ground surface temperature changes is presented. Analytical expressions for the average ground temperature are derived by integrating the exact solution over the line-source depth. A self-consistent procedure to evaluate the in situ thermal response test

Tatyana V. Bandos; Álvaro Montero; Esther Fernández; Juan Luis G. Santander; José María Isidro; Jezabel Pérez; Pedro J. Fernández de Córdoba; Javier F. Urchueguía

2009-01-01

191

Experiments on convection heat transfer along a vertical flat plate between pools with different temperatures  

Microsoft Academic Search

This paper reports that to evaluate the heat removal capability of an external water wall-type containment vessel, which is a passive system for containment cooling, thermal-hydraulic behavior in the suppression and outer pools has been examined experimentally. The following results are obtained: A thermal stratification boundary, which separates the pools into an upper high-temperature region and a lower low-temperature region,

Y. Kataoka; T. Fukui; S. Hatamiya; T. Nakao; M. Naitoh; I. Sumida

1992-01-01

192

A susceptor with a ?-shaped slot in a vertical MOCVD reactor by induction heating  

NASA Astrophysics Data System (ADS)

By using the numerical simulation for the temperature field in the metal organic vapor deposition (MOCVD) reactor by induction heating, it is found that the temperature distribution in the conventional cylinder-shaped susceptor is nonuniform due to the skin effect of the induced current, which makes the temperature distribution of the wafer nonuniform. Therefore, a novel susceptor with a ∧-shaped slot is proposed. This slot changes the mode and the rate of the heat transfer in the susceptor, which improves the uniformity of the temperature distribution in the wafer. By using the finite element method (FEM), the susceptor with this structure for heating a wafer of four inches in diameter is optimized. It is observed that the optimized susceptor with the ∧-shaped slot makes the uniformity of the temperature distribution in the wafer improve by more than 85%, and a good uniformity of temperature distributions is kept under different wafer temperatures, which may be beneficial to the film growth.

Zhiming, Li; Hailing, Li; Xiaobing, Gan; Haiying, Jiang; Jinping, Li; Xiaoqian, Fu; Yanbin, Han; Yingjie, Xia; Jianqin, Yin; Yimei, Huang; Shigang, Hu

2014-09-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

194

Heat pump R and D at Oak Ridge National Laboratory  

SciTech Connect

The objective of this program is to develop technology, concepts, and design tools to improve the performance, reliability, and cost-effectiveness of electric heat pumps using air and alternative heat sources such as well water or earth-coupled heat exchangers. Laboratory studies of air-source heat pumps, conducted to date, include system and component performance evaluations at steady state and under frosting conditions. A computer model of electric motor driven heat pumps was developed to explore the practical limits of steady-state heating efficiency of conventional air-source heat pumps, and to demonstrate an approach to computer-aided heat pump design techniques. Other analytical projects include scoping calculations of alternative heat pump systems, such as air-cycle heat pumps and electric motor driven Stirling heat pumps (not Stirling engine driven vapor compression cycles). Computer programs were written to model the expected performance of vertical-pipe ground-coupled heat exchangers, and for the detailed performance analysis of air-to-refrigerant heat exchangers with complex refrigerant circuiting by calculating the performance of each tube of the heat exchanger individually. A capability was developed for estimating seasonal performance factors for air-source heat pumps using hour-by-hour calculations with empirical temperature dependent degradation factors. Technical accomplishments are described.

Ellison, R.D.; Creswick, F.A.

1981-01-01

195

Secondary atomisation produced by single drop vertical impacts onto heated surfaces  

SciTech Connect

The paper reports an experimental analysis of the secondary atomisation produced by the impact of a single drop on a solid heated surface. Different wall temperatures were used to study different boiling regimes. The size of secondary drops produced by the impact was measured by two techniques, namely the phase Doppler anemometry (PDA) and the image analysis technique (IAT); this allowed to extend the measurable size range from 5.5{mu}m up to few mm. Two impacting walls with different surface roughness were used to show the effect of this parameter on different atomisation regimes. The liquid viscosity was also varied in a limited range by using water-glycerol mixtures. Image analysis allowed also to define the details of the morphology of drop spreading and break-up.

Cossali, G.E.; Marengo, M.; Santini, M. [Universita di Bergamo, Facolta di Ingegneria, viale Marconi 5, 24044 Dalmine (BG) (Italy)

2005-09-01

196

New data on two-phase two-component heat transfer and hydrodynamics in a vertical tube  

NASA Astrophysics Data System (ADS)

In forced-convective two-phase, two component (gas-liquid) flow, experimental data for mean heat-transfer coefficients, pressure drop and flow patterns were taken simultaneously for the flow in a 1.17-cm i.d. electrically heated vertical tube using three liquids: water, glycerine and water and silicone liquid with air as the gas phase. The combination of silicone liquid and the glycerine and water solution provided a set of data in which the surface tension changed by a factor of 3.4 (being lower for the silicone liquid) with a rough matching of other hydrodynamic properties and a precise matching of the Prandtl number (63 at 25 C). The flow-pattern results showed a significant change in the bubble-slug boundary for the silicone liquid compared with the glycerine and water solution, while the pressure drop results for silicone-air, in the range of V(SL) between 0.277 and 0.690 m/s at high V(SC) showed a sudden drop in Delta/P(tot) followed by a subsequent increase.

Rezkallah, K. S.; Sims, G. E.

1987-06-01

197

A Study on a Performance of Water-Spray-Type Ice Thermal Energy Storage Vessel with Vertical Heat Exchanger Plates  

NASA Astrophysics Data System (ADS)

A system with a water-embedded-trpe ice storage vessel is widely used because of its simple structure and compactness. However, the water-embedded-type ice storage vessel has a disadvantage, that is, the solidification 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 a previous study that the use of the falling water film is very effective, especially for high initial water temperatures. In the present study, we eexamined the performance of a faling-water-film-type ice thermal energy storage vessel with pratical size, having vertical heat exchanger plates. The ice making performance coefficient, ?, increases with time, and it becomes am aximum value of 2.5, after that, it decreases gradually. In order to make ice efficiently, it is necessary to set a flow rate of refrigerant properly and to adjust a difference between the evaporating temperature of refrigerant and the freezing point of water so that the refrigerant evaporates in the heat exchanger plates overall.

Yoshimura, Kenji; Sasaguchi, Kengo; Fukuda, Toshihito; Koyama, Shigeru

198

Heat transfer, pressure drop and void fraction in two- phase, two-component flow in a vertical tube  

NASA Astrophysics Data System (ADS)

There are very few data existing in two-phase, two- component flow where heat transfer, pressure drop and void fraction have all been measured under the same conditions. Such data are very valuable for two-phase heat-transfer model development and for testing existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction. An experiment was performed which adds markedly to the available data of the type described in terms of the range of gas and liquid flow rates and liquid Prandtl number. Heat transfer and pressure drop measurements were taken in a vertical 11.68-mm i.d. tube for two-phase (gas-liquid) flows covering a wide range of conditions. Mean void fraction measurements were taken, using quick- closing valves, in a 12.7-mm i.d. tube matching very closely pressures, temperatures, gas-phase superficial velocities and liquid-phase superficial velocities to those used in the heat-transfer and pressure-drop experiments. The gas phase was air while water and two aqueous solutions of glycerine (59 and 82% by mass) were used as the liquid phase. In the two-phase experiments the liquid Prandtl number varied from 6 to 766, the superficial liquid velocity from 0.05 to 8.5 m/s, and the superficial gas velocity from 0.02 to 119 m/s. The measured two-phase heat-transfer coefficients varied by a factor of approximately 1000, the two-phase frictional pressure drop ranged from small negative values (in slug flow) to 93 kPa and the void fraction ranged from 0.01 to 0.99; the flow patterns observed included bubble, slug, churn, annular, froth, the various transitions and annular-mist. Existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and/or void fraction were: tested against the present data for mean heat-transfer coefficients. It was found that the methods with more restrictions (in terms of the applicable range of void fraction, liquid Prandtl number or liquid superficial Reynolds number) give better predictions. Among the most restrictive methods, the method of Drucker et al. is recommended. A method less restrictive, but still giving good predictions, is the Liquid Acceleration Model for superficial liquid Reynolds numbers greater than 2000. For local heat-transfer coefficients, a method proposed by Vijay, where Spalding's single-phase boundary-layer theory was adapted to the two-phase case, was tested considering the flow patterns individually and various methods of calculating two-phase properties. Good predictions were obtained for the case of bubble and froth flows when liquid properties were used as the two- phase mixture properties.

Sujumnong, Manit

1998-09-01

199

association of companies and the Edison Electric Institute (1953). Their final report cites investigations from 1945 through 1953 and includes correlated information on coil data, heat  

E-print Network

of electricity has increased, interest has again been focused on the ground-coupled heat pump system. Metz (1979-coupled heat pump with a single pipe horizontal coil. The system was installed as part of the Tennessee Energy of Tennessee. The ground-coupled heat pump system was installed in TECH House I, which is a 1800 ft2 (165 m2

Oak Ridge National Laboratory

200

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

NASA Astrophysics Data System (ADS)

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.

Adebiyi, A.; Zuidema, P.

2012-12-01

201

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

202

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

Microsoft Academic Search

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

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

2007-01-01

203

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

E-print Network

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...

Rehault, N.; Kalz, D.

2012-01-01

204

Heat flux measurement from vertical temperature profile and thermal infrared imagery in low-flux fumarolic zones  

NASA Astrophysics Data System (ADS)

Hydrothermal systems are associated to most of the dormant volcanoes. Heat is transported by steam from the hot magma body in the connected porosity and the fissures of the rock to the surface. If the flux is low enough (<500 W/m²), the steam mainly condensates in the soil close to surface, and a significant proportion of the heat is transported to the surface by conduction, producing a gradient of temperature and a thermal anomaly detectable at the surface. Detecting and monitoring these fluxes is crucial for hazard management, since it reflects the state of the magma body in depth. In order to quantify this flux two methods are considered. First, a vertical profile of temperature is measured by a series of thermocouples, and the conducted flux is estimated thanks to the Fourier law. Secondly, a more recent method uses the thermal infrared imagery to monitor the surface temperature anomaly (STA) between the studied zone and an equivalent zone not affected by the geothermal flux. The heat flux from the soil to the atmosphere is computed as the sum of (1) the radiative flux, (2) the sensible flux and (3) the residual steam flux. These two methods are complementary and have an equivalent uncertainty of approximately 20%, which would allow to track the major changes in the hydrothermal system. However, the surface and sub-surface temperatures are strongly influenced by the climate. For instance, it has been widely demonstrated that the surface temperature dramatically decreases after a rainfall. In order to estimate the reliability of the measurements, a numerical model simulating the evolution of the subsurface temperature in low flux fumarolic zone has been built. In depth, the heat can be transported either by conduction, or by the rising steam, or by condensed water. In surface, both the radiative flux and the sensible flux (convection of the atmosphere) are taken into account. This model allows to estimate the changes of temperature due to a variation of solar illumination, wind, or rainfalls. It has been successfully tested during 5 months with a permanent station built on the Ty fault on La Soufrière volcano (Guadeloupe, Lesser Antilles). Results show that the diurnal cycle has a significant influence on the temperature up to ca. 30 cm depth, hindering the use of the thermal gradient in this zone, while the STA has a negligible variation. Rain has a more dramatic influence: the surface temperature and the STA are significantly affected, even for small rains. The model shows that the drop of temperature and the affected thickness are mainly controlled by the amount of rain, while the relaxation time is primarily a function of the heat flux. These results have strong implications in the interpretation and the reliability of the temperature surveys, and could be used to correct them from the climate fluctuations.

Gaudin, Damien; Finizola, Anthony; Beauducel, François; Brothelande, Elodie; Allemand, Pascal; Delacourt, Christophe; Delcher, Eric; Peltier, Aline

2014-05-01

205

Convection heat transfer of CO{sub 2} at supercritical pressures in a vertical mini tube at relatively low reynolds numbers  

SciTech Connect

Convection heat transfer of CO{sub 2} at supercritical pressures in a 0.27 mm diameter vertical mini tube was investigated experimentally and numerically for upward and downward flows at relatively low inlet Reynolds numbers (2900 and 1900). The effects of inlet temperature, pressure, mass flow rate, heat flux, flow direction, buoyancy and flow acceleration on the convection heat transfer were investigated. For inlet Reynolds numbers less than 2.9 x 10{sup 3}, the local wall temperature varies non-linearly for both flow directions at high heat fluxes (113 kW/m{sup 2}). For the mini tube used in the current study, the buoyancy effect is normally low even when the heating is relatively strong, while the flow acceleration due to heating can strongly influence the turbulence and reduce the heat transfer for high heat fluxes. For relatively low Reynolds numbers (Re{sub in} {<=} 2.9 x 10{sup 3}) and the low heat flux (30.0 kW/m{sup 2}) the predicted values using the LB low Reynolds number correspond well with the measured data. However, for the high heat flux (113 kW/m{sup 2}), the predicted values do not correspond well with the measured data due to the influence of the flow acceleration on the turbulence. (author)

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

2008-09-15

206

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

NASA Astrophysics Data System (ADS)

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

Ghaffari, H. T.; Jones, R. F.

1981-04-01

207

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

Microsoft Academic Search

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

H. T. Ghaffari; R. F. Jones

1981-01-01

208

Experimental investigation on heat transfer of forced convection condensation of ethanol-water vapor mixtures on a vertical mini-tube  

NASA Astrophysics Data System (ADS)

In this paper, condensation heat transfer characteristics of ethanol-water vapor mixtures on a vertical mini-vertical tube with 1.221 mm outside diameter were investigated experimentally. The experiments were performed at different velocities and pressures over a wide range of ethanol mass fractions in vapor. The test results indicated that, with respect to the change of the vapor-to-surface temperature difference, the condensation curves of the heat transfer coefficients revealed nonlinear characteristics, and had peak values. At 2 % ethanol mass fraction in vapor, the condensation heat transfer coefficient value of the ethanol-water vapor mixture was found to have a maximum heat transfer coefficient of 50 kW m-2 K-1, which was 3-4 times than that of pure steam. The condensation heat transfer coefficients decreased with increased ethanol mass fraction in vapor. The vapor pressure and vapor velocity had a positive effect on the condensation heat transfer coefficients of ethanol-water vapor mixtures.

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

2013-09-01

209

Intraseasonal variations in the surface layer heat balance of the central equatorial Indian Ocean: The importance of zonal advection and vertical mixing  

NASA Astrophysics Data System (ADS)

examine the ocean mixed layer response to intraseasonal atmospheric forcing using moored time series data in the central equatorial Indian Ocean for October 2004 to March 2005, a period coincident with two active phases of the Madden-Julian Oscillation (MJO). Both MJO events were accompanied by a sea surface temperature decrease that was partially the consequence of reduced net surface heat flux. In addition, during the first event in October-November 2004, advection by an enhanced Wyrtki Jet contributed substantial cooling, while during the second event in December 2004 to January 2005, vertical processes, most likely related to entrainment mixing, were pronounced. Heavy rainfall at the mooring location during the first event may have contributed to the formation of a 30-40 m thick barrier layer that limited turbulent vertical transfers between the mixed layer and the thermocline. There was no barrier layer present during the second event, which presumably allowed for much freer vertical turbulent exchanges.

McPhaden, M. J.; Foltz, G. R.

2013-06-01

210

Impact of black carbon aerosol over Italian basin valleys: high-resolution measurements along vertical profiles, radiative forcing and heating rate  

NASA Astrophysics Data System (ADS)

A systematic study of black carbon (BC) vertical profiles measured at high-resolution over three Italian basin valleys (Terni Valley, Po Valley and Passiria Valley) is presented. BC vertical profiles are scarcely available in literature. The campaign lasted 45 days and resulted in 120 measured vertical profiles. Besides the BC mass concentration, measurements along the vertical profiles also included aerosol size distributions in the optical particle counter range, chemical analysis of filter samples and a full set of meteorological parameters. Using the collected experimental data, we performed calculations of aerosol optical properties along the vertical profiles. The results, validated with AERONET data, were used as inputs to a radiative transfer model (libRadtran). The latter allowed an estimation of vertical profiles of the aerosol direct radiative effect, the atmospheric absorption and the heating rate in the lower troposphere. The present measurements revealed some common behaviors over the studied basin valleys. Specifically, at the mixing height, marked concentration drops of both BC (range: from -48.4 ± 5.3 to -69.1 ± 5.5%) and aerosols (range: from -23.9 ± 4.3 to -46.5 ± 7.3%) were found. The measured percentage decrease of BC was higher than that of aerosols: therefore, the BC aerosol fraction decreased upwards. Correspondingly, both the absorption and scattering coefficients decreased strongly across the mixing layer (range: from -47.6 ± 2.5 to -71.3 ± 3.0% and from -23.5 ± 0.8 to -61.2 ± 3.1%, respectively) resulting in a single-scattering albedo increase along height (range: from +4.9 ± 2.2 to +7.4 ± 1.0%). This behavior influenced the vertical distribution of the aerosol direct radiative effect and of the heating rate. In this respect, the highest atmospheric absorption of radiation was predicted below the mixing height (~ 2-3 times larger than above it) resulting in a heating rate characterized by a vertical negative gradient (range: from -2.6 ± 0.2 to -8.3 ± 1.2 K day-1 km-1). In conclusion, the present results suggest that the BC below the mixing height has the potential to promote a negative feedback on the atmospheric stability over basin valleys, weakening the ground-based thermal inversions and increasing the dispersal conditions.

Ferrero, L.; Castelli, M.; Ferrini, B. S.; Moscatelli, M.; Perrone, M. G.; Sangiorgi, G.; D'Angelo, L.; Rovelli, G.; Moroni, B.; Scardazza, F.; Mo?nik, G.; Bolzacchini, E.; Petitta, M.; Cappelletti, D.

2014-09-01

211

A rigorous bound on the vertical transport of heat in Rayleigh-Bénard convection at infinite Prandtl number with mixed thermal boundary conditions  

NASA Astrophysics Data System (ADS)

A rigorous upper bound on the Nusselt number is derived for infinite Prandtl number Rayleigh-Bénard convection for a fluid constrained between no-slip, mixed thermal vertical boundaries. The result suggests that the thermal boundary condition does not affect the qualitative nature of the heat transport. The bound is obtained with the use of a nonlinear, stably stratified background temperature profile in the bulk, notwithstanding the lack of boundary control of the temperature due to the Robin boundary conditions.

Whitehead, Jared P.; Wittenberg, Ralf W.

2014-09-01

212

Convection Heat and Mass Transfer in a Power Law Fluid with Non Constant Relaxation Time Past a Vertical Porous Plate in the Presence of Thermo and Thermal Diffusion  

NASA Astrophysics Data System (ADS)

The paper investigates convection heat and mass transfer in power law fluid flow with non relaxation time past a vertical porous plate in presence of a chemical reaction, heat generation, thermo diffu- sion and thermal diffusion. The non - linear partial differential equations governing the flow are transformed into ordinary differential equations using the usual similarity method. The resulting similarity equations are solved numerically using Runge-Kutta shooting method. The results are presented as velocity, temperature and concentration profiles for pseudo plastic fluids and for different values of parameters governing the prob- lem. The skin friction, heat transfer and mass transfer rates are presented numerically in tabular form. The results show that these parameters have significant effects on the flow, heat transfer and mass transfer.

Olajuwon, B. I.; Oyelakin, I. S.

2012-12-01

213

Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption  

NASA Astrophysics Data System (ADS)

The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ˜ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

Johnson, Jeffrey B.; Malone, Stephen D.

2007-06-01

214

The effect of transpiration on coupled heat and mass transfer in mixed convection over a vertical plate embedded in a saturated porous medium  

SciTech Connect

Effect of transpiration velocity on the heat and mass transfer characteristics of mixed convection about a permeable vertical plate embedded in a saturated porous medium under the coupled effects of thermal and mass diffusion is numerically analyzed. The plate is maintained at a uniform temperature and species concentration with constant transpiration velocity. The transformed governing equations are solved by Keller box method. Numerical results for the local Nusselt number and local Sherwood number are presented. In general, it has been found for thermally assisted flow that the local surface heat and mass transfer rates increase owing to suction of fluid. This trend reversed for blowing of fluid. It is apparent that the Lewis number has a pronounced effect on the local Sherwood number than it does on the local Nusselt number. Increasing the Lewis number decreases (increases) the local heat (mass) transfer rate.

Yih, K.A. [Air Forces Inst. of Aeronautical Technology, Kaoshiuang (Taiwan, Province of China). Dept. of General Course] [Air Forces Inst. of Aeronautical Technology, Kaoshiuang (Taiwan, Province of China). Dept. of General Course

1997-03-01

215

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

PubMed

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

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

2014-01-01

216

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

PubMed Central

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

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

2014-01-01

217

Heat transfer modeling in the vertical tubes of the passive containment cooling system of the simplified boiling water reactor  

Microsoft Academic Search

The long term containment cooling of GE's passive BWR design is based on a new safety system called PCCS (passive containment cooling system). Performance of this system relies on the pressure difference between the drywell and wetwell in case of an accident and on the condensation of steam moving downward inside vertical tubes fully submerged in a water pool initially

Luis E. Herranz; José L. Muñoz-Cobo; G. Verdú

1997-01-01

218

Effect of heat generated by an exothermic reaction on the fully developed mixed convection flow in a vertical channel  

NASA Astrophysics Data System (ADS)

The steady fully developed mixed convection flow in a vertical channel with first-order chemical reaction has been investigated in this paper. The dimensionless governing ordinary differential equations have been solved numerically. It is found that dual solutions exist for both velocity and temperature.

Pop, Ioan; Grosan, Teodor; Cornelia, Revnic

2010-03-01

219

Numerical simulation and experimental analysis of heat transfer through the neck tube into vertical cryogenic insulated cylinders  

NASA Astrophysics Data System (ADS)

The neck tube is an important support structure in cryogenic insulated cylinders. The heat flux from the outside environment through the neck tube into the cryogenic liquid occupies a great proportion of the total heat leak and can be more than half of the total heat loads. In this paper, conjugate convective-conductive heat transfer model between wall and the cold vapor in conditions of natural discharge is numerically investigated. Also a liquid nitrogen boil-off method was adopted in experiments to validate the result of numerical simulation. Experimental results indicate more favorable agreement with conjugate heat transfer (CHT) model compared with simple solid heat conduction (SSHC) model by ANSYS software. And the convection between the wall and vapor is also calculated. The research and results can provide reference in design for neck tube of the cryogenic cylinder.

Li, Yang; Wang, Caili; Wang, Rongshun

2011-07-01

220

Heat transfer, pressure drop and void fraction in two- phase, two-component flow in a vertical tube  

Microsoft Academic Search

There are very few data existing in two-phase, two- component flow where heat transfer, pressure drop and void fraction have all been measured under the same conditions. Such data are very valuable for two-phase heat-transfer model development and for testing existing heat-transfer models or correlations requiring frictional pressure drop (or wall shear stress) and\\/or void fraction. An experiment was performed

Manit Sujumnong

1998-01-01

221

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

E-print Network

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...

Andolsun, S.; Culp, C.

2011-01-01

222

Experimental studies on the enhanced flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in vertical porous coated tube  

NASA Astrophysics Data System (ADS)

The characteristics of flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.

Yang, Dong; Shen, Zhi; Chen, Tingkuan; Zhou, Chenn Q.

2013-07-01

223

Possible reasons for underestimating Joule heating in global models: E field variability, spatial resolution, and vertical velocity  

Microsoft Academic Search

It is important to understand Joule heating because it can significantly change the temperature structure, atmosphere composition, and electron density and hence influences satellite drag. It is thought that many coupled ionosphere-thermosphere models underestimate Joule heating because the spatial and temporal variability of the ionospheric electric field is not totally captured within global models. Using the Global Ionosphere Thermosphere Model

Yue Deng; Aaron J. Ridley

2007-01-01

224

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

PubMed

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

Mutuku-Njane, Winifred Nduku; Makinde, Oluwole Daniel

2013-01-01

225

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

PubMed Central

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

2013-01-01

226

Infrasound and Seismic Observation of the Hayabusa Reentry: Burst Signals and Air-to-Ground Coupling Process  

NASA Astrophysics Data System (ADS)

The Hayabusa, the world's first sample-return minor body explorer, reentered the Earth's atmosphere on June 13, 2010. This was the third direct reentry event from the interplanetary transfer orbit to the Earth at a velocity of over 11.2 km/s, and was the world's first case of a direct reentry of the spacecraft itself from the interplanetary transfer orbit. This was the very good and rare opportunity to study bolide class meteor phenomena by various aspects. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area, Australia (Fujita et al., 2011). The observations were configured with optical imaging, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations (GOS2, GOS2A, and GOS2B), we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations (GOS2B-sub1, to GOS2B-sub3) (Yamamoto et al., 2011; Ishihara et al., 2012). The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa sample return capsule (Ishihara et al., 2012). In addition, following capsule signal, lots of signals that probably correspond shockwave from disrupted fragments of spacecraft and energetic bursts of the spacecraft were also recorded (Yamamoto et al., 2011). In this study, we analyze signals generated by hypersonic motion of the disrupted fragments and energetic burst of the spacecraft. In addition, we examine the air-to-ground coupling process by comparing the waveforms computed by finite difference scheme with the actual ones. At all three arrayed main stations, after the capsule's shockwave arrival, we detect multiple shockwave signals by both infrasound and seismic sensors. For some of these signals arrive within 10 seconds after capsule's signal, we can identify one to one correspondence with optically tracked disrupted fragments of the spacecraft. Far after the capsule's signal, we also detect some arrivals of wave packets. Based on the arrival time and the slowness of the signals, we identified one of these signals as the shockwave signal that corresponds to the energetic burst of the spacecraft at altitude of 57.3 km, which was recorded by video. However, we could not identify a lot of signals as the direct arrivals of the burst and sonic-boom-type shockwave. Some of those unidentified signals were probably related the multipath phases of the burst and sonic boom shockwaves. To study the air-to-ground coupling, we compare the observed waveforms to synthetic waveforms computed by 2-D finite difference scheme. For the actual seismic data, we can find precursor wave packets slightly prior to the direct-coupled wave from the capsule at GOS2 and GOS2A station. On the other hand, GOS2B and sub stations did not recorded distinct precursor wave. According to the synthetic waveforms, apparent velocity of the incident air-pressure wave controls the existence of the precursor wave prior to the direct coupling. When the apparent velocity of the incident pressure wave is almost identical to the phase velocity of ground surface wave, the surface wave is excited efficiently as precursor wave. Namely, for GOS2B station, the elevation angle of the incident shockwave is high. Therefore, the apparent velocity of the shockwave is too fast to generate the precursor surface wave.

Ishihara, Y.; Hiramatsu, Y.; Yamamoto, M.; Furumoto, M.; Fujita, K.

2012-12-01

227

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

E-print Network

objective. of. this study was to measure the free convective velocity and. temperature distribution of air along a flat vertical plate. held, at a relatively low temperature. A thin aluminum plate installed, inside a free-convection chamber was used... for this purpose. The chamber dry bulb temperature was maintained between 81' and 84' F and the plate temperature held constant at -2. 2' F or -4' F. The air velocity was measured by a hot wire anemometer and the. temperature measured by a copper- constantan...

Jullienne, Jean Maxime Jose

2012-06-07

228

Forced and mixed convection heat transfer to supercritical CO{sub 2} vertically flowing in a uniformly-heated circular tube  

SciTech Connect

An experiment of heat transfer to CO{sub 2}, which flows upward and downward in a circular tube with an inner diameter of 6.32 mm, was carried out with mass flux of 285-1200 kg/m{sup 2} s and heat flux of 30-170 kW/m{sup 2} at pressures of 7.75 and 8.12 MPa, respectively. The corresponding Reynolds number at the tube test section inlet ranges from 1.8 x 10{sup 4} to 3.8 x 10{sup 5}. The tube inner diameter corresponds to the equivalent hydraulic diameter of the fuel assembly sub-channel, which is being studied at KAERI. Among the tested correlations, the Bishop correlation predicted the experimental data most accurately, but only 66.9% of normal heat transfer data were predicted within {+-}30% error range. The Watts and Chou correlation, which is claimed to be valid for both the normal and deteriorated heat transfer regime, showed unsatisfactory performance. A significant decrease in Nusselt number was observed in the range of 10{sup -6}heat transfer deterioration regime. The heat transfer deteriorated when the value of the buoyancy parameter Gr{sub b}/Re{sub b}{sup 2.7} exceeded 2.0 x 10{sup -5} close to the Jackson and Hall's criterion. As soon as the heat transfer deteriorated, it entered a new regime and did not return to a normal heat transfer regime, although the value of buoyancy parameter Gr{sub b}/Re{sub b}{sup 2.7} reduced below the deterioration criterion 2.0 x 10{sup -5}. It may justify the requirement of developing separate correlations for the normal and deterioration regimes, as proposed in this paper. (author)

Bae, Yoon-Yeong; Kim, Hwan-Yeol [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong, Daejeon 305-353 (Korea); Kang, Deog-Ji [Korea Hydro and Nuclear Power Co. Ltd., 216 Kori, Jangan-eup, Gijang-gun, Busan 619-711 (Korea)

2010-11-15

229

Transient radiative hydromagnetic free convection ?ow past an impulsively started vertical plate with uniform heat and mass ?ux  

Microsoft Academic Search

The interaction of free convection with thermal radiation of viscous incompressible MHD unsteady ?ow past an impulsively started ver- tical plate with uniform heat and mass ?ux is analyzed. This type of problem flnds application in many technological and engineer- ing flelds such as rocket propulsion systems, space craft re-entry aerothermodynamics, cosmical ?ight aerodynamics, plasma physics, glass production and furnace

V. Ramachandra Prasad; N. Bhaskar Reddy; R. Muthucumaraswamy

230

Heat Transfer Analysis of MHD Thin Film Flow of an Unsteady Second Grade Fluid Past a Vertical Oscillating Belt.  

PubMed

This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed. PMID:25383797

Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

2014-01-01

231

Heat Transfer Analysis of MHD Thin Film Flow of an Unsteady Second Grade Fluid Past a Vertical Oscillating Belt  

PubMed Central

This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed. PMID:25383797

Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

2014-01-01

232

Local heat transfer coefficients for forced-convection condensation of steam in a vertical tube in the presence of a noncondensable gas  

SciTech Connect

An experimental investigation has been conducted to determine the local condensation heat transfer coefficient (HTC) of steam in the presence of air or helium flowing downward inside a 46-mm-i.d. vertical tube. The gas-steam mixture flow rate was measured with a calibrated vortex flowmeter before it entered the 2.54-m-long test condenser. Cooling water flow rate in an annulus around the tube was measure with a calibrated rotameter. Temperatures of the cooling water, the gas-steam mixture, and the tube inside and outside surfaces were measured at 0.3-m intervals in the test condenser. Inlet and exit pressures and temperatures of the gas-steam mixture and of the cooling water were also measured. The local heat flux was obtained from the slope of the coolant axial temperature profile and the coolant mass flow rate. It was found that for the same mass fraction of the noncondensable gas, compared with air, helium has a more inhibiting effect on the heat transfer, but for the same molar ratio, air was found to be more inhibiting. An application where there is important is the proposed advanced passive boiling water reactor design (Simplified Boiling Water Reactor), which utilizes the isolation condenser as a main component of the passive containment cooling system (PCCS).

Siddique, M.; Golay, M.W.; Kazimi, M.S. (Massachusetts Inst. of Tech., Cambridge (United States))

1993-06-01

233

Comment on Magnetohydrodynamic non-Darcy mixed convection heat transfer from a vertical heated plate embedded in a porous medium with variable porosity, by Dulal Pal  

E-print Network

In the above paper the author treats the boundary layer flow along a vertical flat plate, immersed in a Darcy Brinkman Forchheimer porous medium. The porosity and the permeability of the porous medium are variable across the boundary layer. In addition a magnetic field with constant strength is applied normal to the plate. The fluid temperature at the plate is constant and different from that of the ambient fluid. This temperature difference creates a buoyancy force and the flow is characterized as mixed convection. The partial differential equations of the boundary layer flow are transformed into ordinary differential equations and subsequently are solved with the Runge-Kutta Fehlberg method. The results are presented in two tables and 11 figures.

Pantokratoras, Asterios

2014-01-01

234

On demand shape-selective integration of individual vertical germanium nanowires on a Si(111) substrate via laser-localized heating.  

PubMed

Semiconductor nanowire (NW) synthesis methods by blanket furnace heating produce structures of uniform size and shape. This study overcomes this constraint by applying laser-localized synthesis on catalytic nanodots defined by electron beam lithography in order to accomplish site- and shape-selective direct integration of vertically oriented germanium nanowires (GeNWs) on a single Si(111) substrate. Since the laser-induced local temperature field drives the growth process, each NW could be synthesized with distinctly different geometric features. The NW shape was dialed on demand, ranging from cylindrical to hexagonal/irregular hexagonal pyramid. Finite difference time domain analysis supported the tunability of the light absorption and scattering spectra via controlling the GeNW shape. PMID:23414075

Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Hwang, David J; Xiang, Bin; Dubon, Oscar D; Minor, Andrew M; Grigoropoulos, Costas P

2013-03-26

235

Effect of thermal-hydrogeological and borehole heat exchanger properties on performance and impact of vertical closed-loop geothermal heat pump systems  

NASA Astrophysics Data System (ADS)

Ground-source geothermal systems are drawing increasing attention and popularity due to their efficiency, sustainability and being implementable worldwide. Consequently, design software and regulatory guidelines have been developed. Interaction with the subsurface significantly affects the thermal performance, sustainability, and impacts of such systems. Reviewing the related guidelines and the design software, room for improvement is evident, especially in regards to interaction with groundwater movement. In order to accurately evaluate the thermal effect of system and hydrogeological properties on a borehole heat exchanger, a fully discretized finite-element model is used. Sensitivity of the loop outlet temperatures and heat exchange rates to hydrogeological, system and meteorological factors (i.e. groundwater flux, thermal conductivity and volumetric heat capacity of solids, porosity, thermal dispersivity, grout thermal conductivity, background and inlet temperatures) are analyzed over 6-month and 25-year operation periods. Furthermore, thermal recovery during 25 years after system decommissioning has been modeled. The thermal plume development, transport and dissipation are also assessed. This study shows the importance of subsurface thermal conductivity, groundwater flow (flux > 10-7 m/s), and background and inlet temperature on system performance and impact. It also shows the importance of groundwater flow (flux > 10-8 m/s) on thermal recovery of the ground over other factors.

Dehkordi, S. Emad; Schincariol, Robert A.

2013-10-01

236

Comment on Influence of convective boundary condition on double diffusive mixed convection from a permeable vertical surface, by P.M. Patil, E. Momoniat, S. Roy, International Journal of Heat and Mass Transfer, 70 (2014) 313-321  

E-print Network

In the above paper the authors treat the boundary layer flow along a stationary, vertical, permeable, flat plate within a vertical free stream. Fluid is sucked or injected through the vertical plate. The fluid species concentration at the plate is constant and different from that of the ambient fluid. It is also assumed that the plate is heated by convection from another fluid with constant temperature with a constant heat transfer coefficient. The temperature and species concentration difference between the plate and the ambient fluid creates buoyancy forces and the flow is characterized as mixed convection. The partial differential equations of the boundary layer flow (Eqs. 1-4 in their paper) are transformed and subsequently are solved numerically using an implicit finite difference scheme in combination with a quasi-linearization technique. The quasi-linearization technique is a Newton-Raphson method. The results are presented in 12 figures.

Pantokratoras, Asterios

2014-01-01

237

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

238

Steady MHD free convection heat and mass transfer flow about a vertical porous surface with thermal diffusion and induced magnetic field  

NASA Astrophysics Data System (ADS)

In this study the thermal diffusion effect on the steady laminar free convection flow and heat transfer of viscous incompressible MHD electrically conducting fluid above a vertical porous surface is considered under the influence of an induced magnetic field. The governing non-dimensional equations relevant to the problem, containing the partial differential equations, are transformed by usual similarity transformations into a system of coupled non-linear ordinary differential equations and will be solved analytically by using the perturbation technique. On introducing the non-dimensional concept and applying Boussinesq's approximation, the solutions for velocity field, temperature distribution and induced magnetic field to the second order approximations are obtained for large suction with different selected values of the established dimensionless parameters. The influences of these various establish parameters on the velocity and temperature fields and on the induced magnetic fields are exhibited under certain assumptions and are studied graphically in the present analysis. It is observed that the effects of thermal-diffusion and large suction have great importance on the velocity, temperature and induced magnetic fields and mass concentration for several fluids considered, so that their effects should be taken into account with other useful parameters associated. It is also found that the dimensionless Prandtl number, Grashof number, Modified Grashof number and magnetic parameter have an appreciable influence on the concerned independent variables.

Touhid Hossain, M. M.; Afruz-Zaman, Md.; Rahman, Fouzia; Hossain, M. Arif

2013-09-01

239

Utilizing satellite-derived estimates of land surface temperature and vegetation characteristics in modeling the vertical water and heat fluxes for a river basin  

NASA Astrophysics Data System (ADS)

New version of the model of vertical water and heat transfer in the "soil-vegetation-atmosphere" system (SVAT) has been developed, accounting for land surface heterogeneities in river basin. The model is specially designed to assimilate satellite data and is intended for calculation of evapotranspiration Ev, soil water content W, sensible and latent heat fluxes and other water and heat balance components as well as vertical soil moisture and temperature profiles and vegetation cover and soil surface temperatures for any time interval within vegetation season. The river basin landscape patchiness is represented in the model with soil constants, leaf area index LAI, vegetation cover fraction B, land surface albedo A, and other vegetation characteristics that were treated as model parameters. The Seim River basin was chosen for investigation, situated in forest-steppe zone of the Central Russia (Kursk region) with watershed area equal to 7460 km2. Satellite-derived estimates of land surface characteristics have been extracted from AVHRR/NOAA (1999-2006 vegetation seasons) and MODIS/EOS Terra and Aqua (2003-2005 vegetation seasons) cloud-free data. The developed technique of AVHRR data processing provides the cloud detection and the retrieval of soil temperature ?sg and emissivity E, surface-air temperature at a level of vegetation cover Ta, effective radiative temperature Ts.eff (weighted linear combination of Ta and Tsg), as well as the derivation of normalized vegetation index NDVI, LAI and B. The updated multi-threshold technique of cloud detection in the AVHRR field of view has been applied to increase the reliability of cloud-free fragments selection. The algorithms of Ta, Ts.eff, Tg derivation utilize linear regression estimators similar to well-known "local" split window technique. The values of E for these regression formulas have been specified using empirical relationships between E and B, E and NDVI as well as the emissivity models for various surface types. To determine B and LAI empirical relationships with NDVI for different land covers have been employed. The comparison of satellite estimates Ta, Ts.eff , Tg with quasi-synchronous in-situ measurements during above vegetation seasons gives RMS errors in the range 2.0-2.7, 2.4-3.5, 3.4-4.8?C respectively. The MODIS-based dataset of remote sensing products, namely, the estimates of Tg, Ts.eff, NDVI, LAI, E for the region of interest and chosen vegetation seasons has been compiled using Internet resources and special technique. While developing new version of the SVAT model, the capabilities have been investigated to calculate Ev, W, LE, H and other water and heat balance components with replacement ground and point-wise estimates of LAI and B by their AVHRR-or MODIS-based (surface-averaged) analogs. The efficiency of such approach has been proved through comparison between satellite-derived, modeled, and in-situ measured temperatures as well as through comparison the modeled and actual values of Ev, W for various soil layer under all scenarios of LAI and B specification. The discrepancies between mentioned temperatures do not exceed the RMS errors of satellite-derived estimates Ta, Tg and Ts.eff while the modeled and measured values of Ev and W have been found close to each other within a standard error of their estimations. Moreover, the ability of using satellite AVHRR- or MODIS-based land surface temperature as the SVAT model variable has been confirmed if the time-matching of satellite and ground-based observations takes place. Thus, the results of our studies allow confirming the efficiency of satellite data utilization in modeling the vertical heat and water transfer processes for vegetation-covered territories under the lack of conventional ground measurements. The present study was carried out with support of the Russian Foundation of Basic Researches - grant N 07-05-01030.

Muzylev, E. L.; Uspensky, A. B.; Startseva, Z. P.; Volkova, E. V.; Kukharsky, A. V.

2009-04-01

240

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

Microsoft Academic Search

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

R. Yumruta?; M. Ünsal

2000-01-01

241

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)

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.

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

2014-10-01

242

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)

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.

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

2014-07-01

243

Experimental Study on the Modeling of Condensation Heat Transfer Coefficients in High Mass Flux Region of Refrigerant HFC134a Inside the Vertical Smooth Tube in Annular Flow Regime  

Microsoft Academic Search

This article presents an experimental investigation on the co-current downward condensation of R134a in a vertical smooth copper tube having inner diameter of 8.1 mm and a length of 500 mm. Condensation experiments are done at mass fluxes varying between 260 and 515 kg\\/m 2 -s. The condensing temperatures are 40 ? C and 50 ? C; heat fluxes are

AHMET S. DALKILIC; SOMCHAI WONGWISES

2011-01-01

244

Viscous dissipation and Joule heating effects on MHD-free convection from a vertical plate with power-law variation in surface temperature in the presence of Hall and ion-slip currents  

Microsoft Academic Search

An analysis is presented to study the effects of viscous dissipation and Joule heating on MHD-free convection flow past a semi-infinite vertical flat plate in the presence of the combined effect of Hall and ion-slip currents for the case of power-law variation of the wall temperature. The fluid is permeated by a strong transverse magnetic field imposed perpendicularly to the

Emad M. Abo-Eldahab; Mohamed A. El Aziz

2005-01-01

245

Vertical Farm  

NSDL National Science Digital Library

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.

2004-01-01

246

Simulating film condensation of steam from steam-gas mixtures with different compositions on the outer surface of vertical tubes used in a heat exchanger  

NASA Astrophysics Data System (ADS)

A mathematical model of heat-and mass transfer processes in surface-type heat exchangers that use mixtures of steam with various noncondensable gases as heat carriers is presented. The results of numerical calculations are compared with experimental data reported in the literature. It is shown that the thermal-physical properties of the noncondensable component in a steam-gas mixture have an essential effect on the distribution of concentrations and temperatures over the heat exchanger length and on the heat flux transferred in it.

Dudnik, N. M.; Garyaev, A. B.

2010-06-01

247

An assessment of ground-coil heat-pump technology  

NASA Astrophysics Data System (ADS)

Results from an analytical comparison of the performance and economics of residential space conditioning with three types of ground coupled heat pump systems and air source systems in ten metropolitan areas of the United States are summarized. Additional results from parametric analyses of the effects of costs, soil properties, operating strategy and alternate system configurations are also summarized.

Fischer, R. D.; Stickford, G. H.; Jakob, F. E.

1984-11-01

248

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

Microsoft Academic Search

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

Vincent Partenay; Peter Riederer; Tristan Salque; Etienne Wurtz

2011-01-01

249

Ground-Source Heat Pumps Applied to Commercial Buildings  

Microsoft Academic Search

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

Steven A. Parker; Donald L. Hadley

2006-01-01

250

Ground-source Heat Pumps Applied to Commercial Buildings  

Microsoft Academic Search

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

Steven A. Parker; Donald L. Hadley

2009-01-01

251

Vertical Launch Third Harmonic Electron Cyclotron Resonance Heating of H-mode on TCV and Access to Quasi-Stationary ELM-free H-mode  

Microsoft Academic Search

The Tokamak à Configuration Variable (TCV) is equipped with three 480 kW gyrotrons operating at 118 GHz. Radiation is launched in the extraordinary mode allowing plasma heating using third harmonic X-mode electron cyclotron resonance heating (ECRH) at density up to 11×1019 m-3. Power is transmitted to the tokamak along 3 evacuated waveguides and is projected onto one plasma facing mirror

L. Porte

2007-01-01

252

Vertical Launch Third Harmonic Electron Cyclotron Resonance Heating of H-mode on TCV and Access to Quasi-Stationary ELM-free H-mode  

NASA Astrophysics Data System (ADS)

The Tokamak à Configuration Variable (TCV) is equipped with three 480 kW gyrotrons operating at 118 GHz. Radiation is launched in the extraordinary mode allowing plasma heating using third harmonic X-mode electron cyclotron resonance heating (ECRH) at density up to 11×1019m-3. Power is transmitted to the tokamak along 3 evacuated waveguides and is projected onto one plasma facing mirror that can be translated radially, between shots, and rotated poloidally during a shot. Linear ray-tracing is adequate tool for estimating the X3 coupled power in H-mode plasma and all estimates of X3 coupled power presented in this paper have been obtained using ray tracing. Experiments were performed to heat H-mode using X3. The target was an ohmic H-mode. Up to 90% of the launched X3 power was coupled to the plasma so that the total heating power (1.3 MW) was about much greater than the ohmic H-mode threshold power (500 kW). This level of coupled power was maintained even in the presence of significant perturbations to the plasma; ELMS. The radiated power was 300 kW during the X3 heated phase. The X3 heated H-mode discharges often transited into an ELM free H-mode regime with constant electron density and stored energy. During the X3 phase the stored energy and ?tor both doubled (?N = 2). The maximum, achieved ?tor was 2.5% while the ideal ?-limit for these discharges was 3.5%. The recycling light level was high compared to the baseline ohmic H-mode level and the fluctuations in the recycling light level were correlated with core MHD. The confinement time for these discharges was found to be as high as 30 ms (HIPB(y,2) = 1.7). Measurements of carbon ion temperature profiles and carbon rotation velocity using charge exchange recombination spectroscopy showed that the ion temperature, near mid radius, increased from 500 eV to 1 keV during the quiescent phase. The plasma rotation increased also from 5 kms-1 to 5 kms-1 in the direction of plasma current.

Porte, L.

2007-09-01

253

Unsteady hydromagnetic convective flow in a vertical channel using Darcy–Brinkman–Forchheimer extended model with heat generation\\/absorption: Analysis with asymmetric heating\\/cooling of the channel walls  

Microsoft Academic Search

In the present paper transient as well as non-Darcian effects on laminar natural convection flow in a vertical channel embedded in a porous medium in the presence of uniform magnetic field applied normal to the flow region is studied. Forchheimer–Brinkman extended Darcy model is assumed to simulate momentum transfer within the porous medium. Approximate solutions are obtained using multi-parameter perturbation

Ajay Kumar Singh; Rajiv Kumar; Usha Singh; N. P. Singh; Atul Kumar Singh

2011-01-01

254

Heat transfer to and from a reversible thermosiphon placed in porous media  

NASA Astrophysics Data System (ADS)

The primary focus of this work is an assessment of heat transfer to and from a reversible thermosiphon imbedded in porous media. The interest in this study is the improvement of underground thermal energy storage (UTES) system performance with an innovative ground coupling using an array of reversible (pump-assisted) thermosiphons for air conditioning or space cooling applications. The dominant mechanisms, including the potential for heat transfer enhancement due to natural convection, of seasonal storage of "cold" in water-saturated porous media is evaluated experimentally and numerically. Winter and summer modes of operation are studied. A set of 6 experiments are reported that describe the heat transfer in both fine and coarse sand in a 0.32 cubic meter circular tank, saturated with water, under freezing (due to heat extraction) and thawing (due to heat injection) conditions, driven by the heat transfer to or from the vertical thermosiphon in the center of the tank. It was found that moderate to strong natural convection was induced at Rayleigh numbers of 30 or higher. Also, near water freezing temperatures (0°C-10°C), due to higher viscosity of water at lower temperatures, almost no natural convection was observed. A commercial heat transfer code, ANSYS FLUENT, was used to simulate both the heating and cooling conditions, including liquid/solid phase change. The numerical simulations of heat extraction from different permeability and temperature water-saturated porous media showed that enhancement to heat transfer by convection becomes significant only under conditions where the Rayleigh number is in the range of 100 or above. Those conditions would be found only for heat storage applications with higher temperatures of water (thus, its lower viscosity) and large temperature gradients at the beginning of heat injection (or removal) into (from) soil. For "cold" storage applications, the contribution of natural convection to heat transfer in water-saturated soils would be negligible. Thus, the dominant heat transfer mechanism for air conditioning applications of UTES can be assumed to be conduction. An evaluation of the potential for heat transfer enhancement in air-saturated media is also reported. It was found that natural convection in soils with high permeability and air saturations near 1 becomes more important as temperatures drop significantly below freezing.

Kekelia, Bidzina

255

The citation for this paper is: Spitler, J.D., X. Liu, S.J. Rees, C. Yavuzturk. 2005. Simulation and Optimization of Ground Source Heat  

E-print Network

will be discussed. Key words: ground source heat pump systems, geothermal, ground-coupled 1 INTRODUCTION UsingThe citation for this paper is: Spitler, J.D., X. Liu, S.J. Rees, C. Yavuzturk. 2005. Simulation Vegas. May 30-June 2. 1 #12;SIMULATION AND OPTIMIZATION OF GROUND SOURCE HEAT PUMP SYSTEMS J.D. Spitler

256

Hybrid Heat Pumps Using Selective Water Sorbents (SWS)  

SciTech Connect

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.

Ally, M.R.

2006-11-30

257

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

Microsoft Academic Search

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

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

2011-01-01

258

Measurement of the vertical profile of atmospheric SO 2 during the heating period in Beijing on days of high air pollution  

NASA Astrophysics Data System (ADS)

This paper reports altitude-resolved concentrations of sulfur dioxide (SO 2) and particulate matter up to 10 microns in diameter (PM 10) in the planetary boundary layer of major urban centers during extreme pollution episodes. The concentration of SO 2 was observed continuously from November 24, 2004, to December 4, 2004, in Beijing during the heating period. Fluorescence SO 2 analyzers were used to measure the atmospheric SO 2 concentrations. Four SO 2 analyzers were placed at 4 different levels (8 m, 47 m, 120 m, and 280 m) of the 325-m high meteorological observation tower of the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences. A maximal SO 2 concentration of 172.3 ppb was measured during this pollution episode, and SO 2 concentration increased with altitude and reached its maximal value at ˜50 m. The study also analyzed the meteorological situation before, during, and after the pollution episode.

Yang, Sun; Yuesi, Wang; Changchun, Zhang

259

Optimizing three-frequency Na, Fe, and He lidars for measurements of wind, temperature, and species density and the vertical fluxes of heat and constituents.  

PubMed

The measurement accuracies of three-frequency resonance fluorescence Doppler lidars are limited by photon noise and uncertainties in the laser frequency and line width. We analyze the performance of Na, Fe, and He lidars using a new technique, which incorporates precise information about the absorption spectrum of the species and the pulse spectrum of the lasers. We derive the measurement errors associated with photon noise, laser frequency errors, and laser line width errors. Optimizing the lidar design, based upon the measurement requirements, can improve system performance by reducing the required integration times, enabling measurements to be made in less time or at higher altitudes where the densities and signal levels are smaller. The optimum frequency shift for observing heat and constituent transport velocities is 689 MHz (580 MHz) at night (day) for Na lidars and 774 MHz (597 MHz) for Fe lidars. The optimum frequency shift for observing winds, temperature, and He densities is 3.66 GHz (3.16 GHz) at night (day) for He lidars. PMID:25089967

Gardner, Chester S; Vargas, Fabio A

2014-07-01

260

Analysis of the energy performance of a ground source heat pump system after five years of operation  

Microsoft Academic Search

GeoCool plant was the result of a EU project whose main purpose was to adapt ground coupled heat pump technology to cooling dominated areas. The execution of this experimental plant was completed at the end of year 2004, starting on February 2005 the regular operation of the air conditioning system. Since then, GeoCool facility has been monitored by a network

C. Montagud; J. M. Corberán; Á. Montero; J. F. Urchueguía

2011-01-01

261

Compact heat exchanger design progress  

Microsoft Academic Search

Development of compact plate type heat exchangers for OTEC plants is reviewed. The heat exchangers have horizontal, single pass water flow, vertical downflow condenser, and vertical upflow boiler passages. The design lends itself to many variations in type of water side configuration, and in boiling and condensing surface design. It makes high heat transfer coefficients possible, along with low pressure

J. H. Anderson Jr.; P. B. Pribis

1979-01-01

262

Offset vertical radar profiling  

USGS Publications Warehouse

Diffraction tomography imaging was applied to VRP data acquired by vertically moving a receiving antenna in a number of wells. This procedure simulated a vertical downhole receiver array. Similarly, a transmitting antenna was sequentially moved along a series of radial lines extending outward from the receiver wells. This provided a sequence of multistatic data sets and, from each data set, a two-dimensional vertical cross-sectional image of spatial variations in wave speed was reconstructed.

Witten, A.; Lane, J.

2003-01-01

263

Methods of testing parameterizations: Vertical ocean mixing  

NASA Technical Reports Server (NTRS)

The ocean's velocity field is characterized by an exceptional variety of scales. While the small-scale oceanic turbulence responsible for the vertical mixing in the ocean is of scales a few centimeters and smaller, the oceanic general circulation is characterized by horizontal scales of thousands of kilometers. In oceanic general circulation models that are typically run today, the vertical structure of the ocean is represented by a few tens of discrete grid points. Such models cannot explicitly model the small-scale mixing processes, and must, therefore, find ways to parameterize them in terms of the larger-scale fields. Finding a parameterization that is both reliable and plausible to use in ocean models is not a simple task. Vertical mixing in the ocean is the combined result of many complex processes, and, in fact, mixing is one of the less known and less understood aspects of the oceanic circulation. In present models of the oceanic circulation, the many complex processes responsible for vertical mixing are often parameterized in an oversimplified manner. Yet, finding an adequate parameterization of vertical ocean mixing is crucial to the successful application of ocean models to climate studies. The results of general circulation models for quantities that are of particular interest to climate studies, such as the meridional heat flux carried by the ocean, are quite sensitive to the strength of the vertical mixing. We try to examine the difficulties in choosing an appropriate vertical mixing parameterization, and the methods that are available for validating different parameterizations by comparing model results to oceanographic data. First, some of the physical processes responsible for vertically mixing the ocean are briefly mentioned, and some possible approaches to the parameterization of these processes in oceanographic general circulation models are described in the following section. We then discuss the role of the vertical mixing in the physics of the large-scale ocean circulation, and examine methods of validating mixing parameterizations using large-scale ocean models.

Tziperman, Eli

1992-01-01

264

Vertical Line Test  

NSDL National Science Digital Library

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.

2010-01-01

265

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

SciTech Connect

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.

Not Available

1993-12-31

266

Micromachined electrostatic vertical actuator  

SciTech Connect

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.

Lee, A.P.; Sommargren, G.E.; McConaghy, C.F.; Krulevitch, P.A.

1999-10-19

267

Micromachined electrostatic vertical actuator  

DOEpatents

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.

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

268

SIMULATION AND OPTIMAL CONTROL OF HYBRID GROUND SOURCE HEAT  

E-print Network

, patience, and support for me during the past four years. His scientific attitude, sharp thinking, broad of Vertical Ground Loop Heat Exchangers - Analytical....... 21 2.1.1.2 Modeling of Vertical Ground Loop Heat

269

Vertical diffusivity of the Western Arctic Ocean halocline  

NASA Astrophysics Data System (ADS)

nearly year-long series of upper ocean temperature, conductivity, and temperature microstructure profiles were collected from an ice camp drifting in the Beaufort Gyre as part of the 1997-1998 Surface Heat Budget of the Arctic Experiment (SHEBA). Geographically, the record includes portions over the deep Canada Basin and the steep bathymetry of the Chukchi Borderlands region. Hydrographically, the record includes "cool," Pacific-origin haloclines, which contain a variety of subsurface temperature maxima, and cold haloclines typical of the Eurasian Basins. We present estimates of the vertical turbulent diffusivity derived from the dissipation rate of thermal variance and calculations of the associated vertical heat fluxes. We find that vertical diffusion proceeds at molecular rates in the deep basins and away from topographic features. While still relatively small, diffusivity is enhanced by 1 order of magnitude near and above the Chukchi Borderlands. The enhanced diffusivity is correlated to an increase in water column strain variance above the Borderlands, providing a linkage between bathymetry, internal wave activity and turbulence. The Chukchi Borderlands play a significant role in heat transport in the Western Arctic. They are a pathway for horizontal heat transport and a hot spot for vertical heat transport. Vertical fluxes make a substantial contribution to the energy balance of the sea ice cover in this region. Heat fluxes between the halocline and underlying Atlantic Water are shown to be small and lacking vertical connection near surface waters.

Shaw, William J.; Stanton, Timothy P.

2014-08-01

270

Waste heat energy recovery system  

Microsoft Academic Search

A heat exchange element is inserted directly into a water heater storage tank of a new or existing water heating system. The heat exchange element is provided with standard pipe thread connections and adapted to be installed in standard threaded openings in conventional tanks. The heat exchange element is an elongate outer tube inserted vertically through the top of the

1981-01-01

271

Vertical structuring of gigantic jets  

NASA Astrophysics Data System (ADS)

Gigantic Jets (GJs) are initiated deep inside the thundercloud as intracloud discharges whose upward-directed leaders manage to escape through the thundercloud top and propagate up to the ionosphere. The speed at which leaders propagate 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. Despite the expected deceleration of an upward-directed leader, GJs are observed to accelerate as they approach the ionosphere. In this letter, we discuss the dependence of the leader speed on current density in the leader stem, and we propose a simple time-dynamic model for GJ propagation that includes the effects of the expansion of the streamer zone adjacent to the leader head. 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.

Silva, Caitano L.; Pasko, Victor P.

2013-06-01

272

Vertical emitting aperture nanoantennas.  

PubMed

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

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

2012-05-01

273

Aiding Vertical Guidance Understanding  

NASA Technical Reports Server (NTRS)

A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

Feary, Michael; McCrobie, Daniel; Alkin, Martin; Sherry, Lance; Polson, Peter; Palmer, Everett; McQuinn, Noreen

1998-01-01

274

Jamming in Vertical Channels  

NASA Astrophysics Data System (ADS)

We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. Grain heights are less than their diameter so the grains resemble antacid tablets, coins, or poker chips. These grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by grain and channel sizes. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories.

Baxter, G. William; Steel, Fiona

2011-03-01

275

Jamming in Vertical Channels  

NASA Astrophysics Data System (ADS)

We experimentally study jamming of cylindrical grains in a vertical channel. The grains have a low aspect-ratio (height/diameter < 1) so their shape is like antacid tablets or poker chips. They are allowed to fall through a vertical channel with a square cross section. The channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. It is observed that grains sometimes jam in this apparatus. In a jam, grains form a stable structure from one side of the channel to the other with nothing beneath them. Jams may be strong enough to support additional grains above. The probability of a jam occurring is a function of the grain height and diameter. We will present experimental measurements of the jamming probability in this system and discuss the relationship of these results to other experiments and theories.

Baxter, G. William; McCausland, Jeffrey; Steel, Fiona

2010-03-01

276

Vertical solar louver project  

NASA Astrophysics Data System (ADS)

The thermal network analysis computer program MICROPAS was used to analyze Vertical Solar Louvers and other reference solar designs in eight selected climates. The results have been used to generate a set of correlation coefficients for use in performance predictions by the Solar Load Ratio method. At low mass VSL were shown to be superior to ordinary direct gain and equal to the trombe wall systems in energy savings. The energy savings advantage of VSL over direct gain disappears in comparable systems of high mass. Identical solar water tanks of oval cross section were compared in the water wall and VSL configurations.

Bier, C. J.

1984-09-01

277

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.

278

'Endurance' Untouched (vertical)  

NASA Technical Reports Server (NTRS)

This navigation camera mosaic, created from images taken by NASA's Mars Exploration Rover Opportunity on sols 115 and 116 (May 21 and 22, 2004) provides a dramatic view of 'Endurance Crater.' The rover engineering team carefully plotted the safest path into the football field-sized crater, eventually easing the rover down the slopes around sol 130 (June 12, 2004). To the upper left of the crater sits the rover's protective heatshield, which sheltered Opportunity as it passed through the martian atmosphere. The 360-degree view is presented in a vertical projection, with geometric and radiometric seam correction.

2004-01-01

279

Multidimensional simulation of saturated nucleate boiling in a vertical channel  

SciTech Connect

Void fraction increase along boiling flows in heated vertical channels may be predicted fairly well from various one-dimensional correlations. However, these predictions do not provide information about the evolution of interfacial area concentration, which is one of the dominant parameters of dispersed gas-liquid flow and depends on the interface structure. In this paper, a three-dimensional Lagrangian simulation of saturated nucleate boiling in a uniformly heated vertical channel is proposed. Vapor is distributed in liquid in the form of discrete bubbles, and liquid-vapor mixture quality increases along the flow through bubble evaporation and additional nucleation.

Kljenak, I.

1996-12-31

280

Observation of picometer vertical emittance with a vertical undulator.  

PubMed

Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic. PMID:23215388

Wootton, K P; Boland, M J; Dowd, R; Tan, Y-R E; Cowie, B C C; Papaphilippou, Y; Taylor, G N; Rassool, R P

2012-11-01

281

4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe (VTL). Machining the fixture for GE Turboshroud. G.S. O'Brien, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

282

Boiling visualization on vertical fins with tunnel-pore structures  

NASA Astrophysics Data System (ADS)

The paper presents experimental studies of nucleate boiling heat transfer from a system of connected horizontal and vertical subsurface tunnels. The experiments were carried out for water at atmospheric pressure. The tunnel external covers were manufactured out of perforated copper foil (holes diameter 0.3 mm), sintered with the mini-fins, formed on the vertical side of the 10 mm high rectangular fins and horizontal inter-fin surface. The image acquisition speed was 493 fps (at resolution 400 × 300 pixels with Photonfocus PHOT MV-D1024-160-CL camera). Visualization investigations aimed to identify nucleation sites and flow patterns and to determine the bubble departure diameter and frequency at various superheats for vertical tunnels. At low superheat vapor bubbles are generated nearly exclusively by the vertical tunnel. At medium values of superheat, pores of the horizontal tunnel activate.

Pastuszko, Robert; Kaniowski, Robert

2012-04-01

283

Vertical Power Dissipation Characteristics of Semiconductor Power Devices  

Microsoft Academic Search

A major challenge in the semiconductor power device technology with continuing shrink in feature sizes and its circuit implementation is power density and heat build-up related problems. This paper discusses a significance of vertical power dissipation characteristics of LDMOS devices with investigating electrical and thermal behaviors under single- and multi-power pulse operations in terms of device substrate dimensions.

Y. S. Chung

2007-01-01

284

A parametric model of vertical eddy fluxes in the atmosphere  

Microsoft Academic Search

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

Jean-François Louis

1979-01-01

285

Functions and Vertical Line Test  

NSDL National Science Digital Library

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.

2010-01-01

286

Building having solar heating system  

Microsoft Academic Search

A building is disclosed with an integrated solar heating system forming a part of the design of the building by a portion of the heating system being the structural support walls in the form of vertically disposed hollow vessels preferably made of metal. Insulation is applied to opposite sides of the vessels. A fluid is circulated from an upper manifold

McHugh

1981-01-01

287

Heat-pipe Earth.  

PubMed

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

Moore, William B; Webb, A Alexander G

2013-09-26

288

Transition from shear to sideways diffusive instability in a vertical slot  

Microsoft Academic Search

The stability of the steady motion of a fluid confined between two differentially heated rigid vertical plates is considered. The thermosolutal instability occurs when a stable constant vertical salinity gradient is present in the fluid. It has been found that, at moderately large values of the solute Rayleigh number, the instability manifests itself in the form of stationary two-dimensional rolls.

Sivagnanam Thangam; Abdelfattah Zebib; C. F. Chen

1981-01-01

289

Analogy between steam condensation on a horizontal tube bundle and on a vertical wall  

Microsoft Academic Search

Experimental results are given for heat transfer with low-pressure steam condensation on the tubes of a test model of a condenser represented by a vertical row of 16 horizontal tubes. The correlation of the results is made assuming an analogy between steam condensation on a vertical wall and on the horizontal tube bundle. Computational relations are suggested for determining the

G. A. Arkhipov; D. I. Volkov; O. I. Makarov; V. A Chistyakov

1989-01-01

290

Heat transport through diffusive interfaces  

NASA Astrophysics Data System (ADS)

We perform a series of 3-D Direct Numerical Simulations (DNS) to assess the vertical heat transport through thermohaline staircases in the Arctic Ocean. The diagnostics of DNS, performed for the first time in the realistic parameter range, result in vertical fluxes exceeding those of extant "four-thirds flux laws" by as much as a factor of 2 and suggest that the 4/3 exponent may require downward revision. Through a series of equivalent 2-D DNS, we show that they are consistent with their more resource-intensive 3-D counterparts for sufficiently large density ratio (R?) but underestimate heat transport for low R?. Finally, we examine the role of boundary conditions in controlling the vertical heat transport. Rigid boundaries—a necessary ingredient in laboratory-derived flux-laws—are shown to reduce the estimates of heat fluxes relative to the corresponding periodic boundary conditions.

Flanagan, Jason D.; Lefler, Angela S.; Radko, Timour

2013-05-01

291

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

E-print Network

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. ...

Iloeje, Onwuamaeze C.

1972-01-01

292

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

E-print Network

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 ...

Back, Larissa E.

293

Analogy between steam condensation on a horizontal tube bundle and on a vertical wall  

SciTech Connect

Experimental results are given for heat transfer with low-pressure steam condensation on the tubes of a test model of a condenser represented by a vertical row of 16 horizontal tubes. The correlation of the results is made assuming an analogy between steam condensation on a vertical wall and on the horizontal tube bundle. Computational relations are suggested for determining the heat transfer coefficient on the steam side for different zones of the condenser.

Arkhipov, G.A.; Volkov, D.I.; Makarov, O.I.; Chistyakov, V.A

1989-01-01

294

Vertically scanned laser sheet microscopy.  

PubMed

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. PMID:25271539

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

2014-10-01

295

Horizontal Inequity and Vertical Redistribution  

Microsoft Academic Search

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

Peter J. Lambert; Xavier Ramos

1997-01-01

296

Geothermal Heat Transfer  

SciTech Connect

This patent describes a heat transfer apparatus which consists of: heat exchanging means for orientation in the earth below ground substantially vertically, having a hollow conduit of length from top to bottom much greater than the span across the hollow conduit orthogonal to its length with a top, bottom and an intermediate portion contiguous and communicating with the top and bottom portions for allowing thermally conductive fluid to flow freely between the top, intermediate and bottom portions for immersion in thermally conductive fluid in the region around the heat exchanging means for increasing the heat flow between the latter and earth when inserted into a substantially vertical borehole in the earth with the top portion above the bottom portion. The heat exchanger consists of heat exchanging conduit means in the intermediate portion for carrying refrigerant. The heat exchanging conduit consisting of tubes of thermally conductive material for carrying the refrigerant and extending along the length of the hollow conduit for a tube length that is less than the length of the hollow conduit. The hollow conduit is formed with port means between the top and the plurality of tubes for allowing the thermally conductive fluid to pass in a flow path embracing the tubes, the bottom portion, an outer channel around the hollow conduit and the port means.

Basmajian, V.V.

1986-01-28

297

Heat exchanger with auxiliary cooling system  

DOEpatents

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.

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

1980-01-01

298

Probing Uranus' Vertical Aerosol Structure at Equinox  

NASA Astrophysics Data System (ADS)

After a decade of quiescence following the Voyager flybys, Uranus' atmosphere has been exhibiting increasing activity approaching equinox that suggests a short timescale, dynamical, response in addition to a long timescale, radiative, response to the seasonal change of hemispheric heating. We propose to investigate this dichotomy by measuring Uranus' vertical aerosol structure over the entire surface, including both poles, at equinox when the forcing insolation is hemispherically symmetric, requiring that the sub-Earth latitude be less than a degree. Only at equinox {every 42 years} can the entire surface of the planet be viewed {over a full rotation} and mapped with the same viewing geometry. We will probe the morphology of the vertical haze structure using NICMOS narrow band filters beyond 1 micron to isolate different altitude regimes between the stratosphere and cloud deck and investigate its change since Cycle 7. We will use two complementary approaches: First, imaging will be done using medium- and narrow-band filters first to locate the dynamically-produced discrete cloud features, then to probe their vertical structure and morphology. The methane absorption bands are stronger in the proposed near-IR {1 to 2.5 microns} than at shorter wavelengths, and the strong H2 pressure-induced absorption from 2.1-2.4 microns contributes to the peak opacity. This enhances the visibility of transient, spatially isolated features and allows their structure to be probed to higher altitudes; namely, to the upper troposphere where they would be evidence of convective overshoot, a dynamical manifestation that would support strong seasonally-induced static instability. In addition to probing the structure with filter photometry, we will measure longitudinal limb profiles to probe the vertical background haze distribution vs latitude. HST/NICMOS is required because it avoids telluric water absorption and OH+O2 emission, and has a stable, well-characterized PSF, essential for limb studies and extracting the vertical structure of fine features crossing the disk. The proposed observations would complement the ground-based Uranus equinox campaign.

Trafton, Laurence

2007-07-01

299

46 CFR 108.160 - Vertical ladders.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical...

2010-10-01

300

Heat pipe array heat exchanger  

DOEpatents

A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

Reimann, Robert C. (Lafayette, NY)

1987-08-25

301

Enhanced Joule Heating in Umbral Dots  

E-print Network

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

Joshi, Chandrashekhar; Jaaffrey, S N A

2007-01-01

302

Enhanced Joule Heating in Umbral Dots  

E-print Network

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

Chandan Joshi; Lokesh Bharti; S. N. A. Jaaffrey

2007-05-08

303

Vertical saccades in dyslexic children.  

PubMed

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

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

2014-11-01

304

Ground-Source Heat Pumps Applied to Commercial Buildings  

SciTech Connect

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.

Parker, Steven A.; Hadley, Donald L.

2006-12-31

305

Convective flows in enclosures with vertical temperature or concentration gradients  

NASA Technical Reports Server (NTRS)

The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

Wang, L. W.; Chai, A. T.; Sun, D. J.

1988-01-01

306

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

Microsoft Academic Search

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

Fang Wang; Maoyu Zheng; Zhongjian Li

2008-01-01

307

Heat generation from electronics increases with the advent of high-density integrated circuit technology. To  

E-print Network

film coating, heat exchangers, combustors, fuel processors, and biomedical and biochemical analysis of a representative microchannel heat exchanger is presented in Fig. 1. Heat flux (q) is applied from the vertical

Boyer, Edmond

308

Measurements of vertical bar Vcb vertical bar and vertical bar Vub vertical bar at BaBar  

SciTech Connect

We report results from the BABAR Collaboration on the semileptonic B decays, highlighting the measurements of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix elements Vub and Vcb. We describe the techniques used to obtain the matrix element |Vcb| using the measurement of the inclusive B {yields} Xclv process and a large sample of exclusive B {yields} D*lv decays. The vertical bar Vub vertical bar matrix elements has been measured studying different kinematic variables of the B {yields} Xulv process, and also with the exclusive reconstruction of B {yields} {pi}({rho})lv decays.

Rotondo, M. [Dipartimento di Fisica Galileo Galilei, Via Marzolo 8, Padova 35131 (Italy)

2005-10-12

309

Vertical motion simulator familiarization guide  

NASA Technical Reports Server (NTRS)

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.

Danek, George L.

1993-01-01

310

Waves, circulation and vertical dependence  

NASA Astrophysics Data System (ADS)

Longuet-Higgins and Stewart (J Fluid Mech 13:481-504, 1962; Deep-Sea Res 11:529-562, 1964) and later Phillips (1977) introduced the problem of waves incident on a beach, from deep to shallow water. From the wave energy equation and the vertically integrated continuity equation, they inferred velocities to be Stokes drift plus a return current so that the vertical integral of the combined velocities was nil. As a consequence, it can be shown that velocities of the order of Stokes drift rendered the advective term in the momentum equation negligible resulting in a simple balance between the horizontal gradients of the vertically integrated elevation and wave radiation stress terms; the latter was first derived by Longuet-Higgins and Stewart. Mellor (J Phys Oceanogr 33:1978-1989, 2003a), noting that vertically integrated continuity and momentum equations were not able to deal with three-dimensional numerical or analytical ocean models, derived a vertically dependent theory of wave-circulation interaction. It has since been partially revised and the revisions are reviewed here. The theory is comprised of the conventional, three-dimensional, continuity and momentum equations plus a vertically distributed, wave radiation stress term. When applied to the problem of waves incident on a beach with essentially zero turbulence momentum mixing, velocities are very large and the simple balance between elevation and radiation stress gradients no longer prevails. However, when turbulence mixing is reinstated, the vertically dependent radiation stresses produce vertical velocity gradients which then produce turbulent mixing; as a consequence, velocities are reduced, but are still larger by an order of magnitude compared to Stokes drift. Nevertheless, the velocity reduction is sufficient so that elevation set-down obtained from a balance between elevation gradient and radiation stress gradients is nearly coincident with that obtained by the aforementioned papers. This paper includes four appendices. The first appendix demonstrates the numerical process by which Stokes drift is excluded from the turbulence stress parameterization in the momentum equation. A second appendix determines a bottom slope criterion for the application of linear wave relations to the derivation of the wave radiation stress. The third appendix explores the possibility of generalizing results by non-dimensionalization. The final appendix applies the basic theory to a problem introduced by Bennis and Ardhuin (J Phys Oceanogr 41:2008-2012, 2011).

Mellor, George

2013-04-01

311

MODELING OF VERTICAL GROUND LOOP HEAT EXCHANGERS FOR GROUND SOURCE  

E-print Network

-dimensional, fully implicit finite volume formulation and utilizes an automated parametric grid generation algorithm to investigate the advantages and the disadvantages of various system operating and control strategies

312

Vertical and Interfacial Transport in Wetlands (Invited)  

NASA Astrophysics Data System (ADS)

The objective of this work is to understand the fluxes connecting the water column, substrate, and atmosphere in wetland environments. To do this, analytical, numerical, and laboratory models have been used to quantify the hydrodynamic contributions to vertical fluxes. A key question is whether the hydrodynamic transport can be modeled as a diffusivity, and, if so, what the vertical structure of this diffusivity is. This question will be addressed in a number of flow types and for a number of fluxes. The fluxes of interest are heat, sediment, dissolved gases (such as methane and oxygen) and other dissolved solutes (such as nutrients and pollutants). The flows of interest include: unidirectional current, reversing flow (under waves, seiches, and tides), wind-sheared surface flows, and thermal convection. Rain and bioturbation can be important, but are not considered in the modeling work discussed herein. Specifically, we will present results on gas transport at wind-sheared free surface, sediment transport in unidirectional flow, and heat transfer in an oscillating flow cause by a seiche. All three of these will be used to consider the question of appropriate analytical models for vertical transport. The analytic models considered here are all 1D models that assume homogeneity in the horizontal plane. The numerical models use finite element methods and resolve the flow around individual vegetation stems in an idealized geometry. Laboratory models discussed herein also use an idealized geometry. Vegetation is represented by an array of cylinders, whose geometry is modeled after Scirpus spp. wetlands in Northern California. The laboratory model is constructed in a way that allows optical access to the flow, even in dense vegetation and far from boundaries. This is accomplished by using fluoropolymer plastics to construct vegetation models. The optical access allows us to employ particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) to measure the velocity and scalar fields, respectively. To study sediment transport, an additional step is needed. Idealized sediment grains are manufactured, again using fluoropolymers. This allows the sediment and fluid phase to be resolved simultaneously, and the velocities of each to be determined independently of the other. The use of fluoropolymers means that the laboratory imaging techniques do not suffer from blockage during laser light delivery or during image capture by digital cameras. Cameras are paired and run in stereoscopic mode to allow three-dimensional velocities to be determined. This is important given the 3D nature of flow through vegetation. Current results from ongoing laboratory, field, and modeling efforts will be discussed, as well as the upcoming steps.

Variano, E. A.

2010-12-01

313

Natural convection between a vertical cylinder and a surrounding array  

SciTech Connect

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.}

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

314

Natural convection between a vertical cylinder and a surrounding array  

SciTech Connect

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.}

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

315

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

Microsoft Academic Search

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

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

2010-01-01

316

Developing mixed convection with aiding buoyancy in vertical tubes: a numerical investigation of different flow regimes  

Microsoft Academic Search

Laminar upward flows with mixed convection in a vertical tube with a uniformly heated zone preceded and followed by adiabatic zones were investigated numerically. Calculations were performed by solving the elliptic Navier–Stokes and energy equations for air and a wide range of heating lengths, Reynolds and Richardson numbers. Different combinations of these parameters establish the existence of five types of

Maher Zghal; Nicolas Galanis; Cong Tam Nguyen

2001-01-01

317

Investigation of the Vertical Bunsen Burner Test for Flammability of Plastics.  

National Technical Information Service (NTIS)

A vertical Bunsen burner test for flammability of plastics (UL-94V) was studied in an attempt to relate the upward burning of plastics to their material fire properties. It was shown that the heat release parameter, the critical heat flux for piloted igni...

B. P. Downey, J. G. Quintiere, R. E. Lyon

2012-01-01

318

Electrically long vertical interconnects for microwave circuits and antennas  

E-print Network

, especially inside on the interior of a structure. In 1996, Colomb et al. published research about "metal on elastomer" interconnects [7]. Metal on elastomer is a "single elastomer piece with embedded gold strips. " The gold sos are oriented vertically... causes the complex epsilon to have a small imaginary part, which translates directly into lower absorplion (heating) loss in the substrate. In addition, standard coaxial transmission lines are filled with Teflon and have a relative dielectric constant...

Coutant, Matthew Richard

2012-06-07

319

Free convection over a vertical porous plate with transpiration  

NASA Technical Reports Server (NTRS)

The problem of free convection over an isothermal vertical porous plate with transpiration is studied both numerically and experimentally. Numerical solutions to the variable-property transpired free-convection boundary layer equations have been obtained using the finite difference procedure of Patankar and Spalding (1967). The effects of uniform transpiration on heat transfer and on temperature and velocity profiles are predicted. Interferometrically measured nondimensional temperature profiles for the uniform wall temperature and transpiration case agreed closely with these numerical predictions.

Parikh, P. G.; Moffat, R. J.; Kays, W. M.; Bershader, D.

1974-01-01

320

Numerical study on the conjugate effect of joule heating and magnato-hydrodynamics mixed convection in an obstructed lid-driven square cavity  

Microsoft Academic Search

Conjugate effect of joule heating and magnetic force, acting normal to the left vertical wall of an obstructed lid-driven cavity saturated with an electrically conducting fluid have been investigated numerically. The cavity is heated from the right vertical wall isothermally. Temperature of the left vertical wall, which has constant flow speed, is lower than that of the right vertical wall.

M. M. Rahman; M. A. Alim; M. M. A. Sarker

2010-01-01

321

7, 1275112779, 2007 Vertical distribution  

E-print Network

boundary layer and vertical distribution of pollutants are discussed in terms15 of the energy balance. In an urban area there are many buildings, which cause large inhomogeneities in the energy and wind profiles Center for the Energy and the Environment (MCE2), La Jolla, CA, USA 2 Department of Earth, Atmospheric

Boyer, Edmond

322

Wideband Fractal Vertical Patch Antenna  

Microsoft Academic Search

A wideband vertical patch antenna (VPA) is depicted, which is devised from fractal antenna technology. By using a dual-Koch loop structure, a wideband VPA with 42% bandwidth and 8 dBi gain at the center frequency is designed and tested. Symmetrical broadside patterns are obtained at the passband.

T. P. Wong; Carmen K. L. Lau; Kwai-Man Luk; Kai-Fong Lee

2007-01-01

323

Insulated vertical antennas above ground  

Microsoft Academic Search

A fast efficient method is proposed to solve the problem of a vertical dielectric-coated antenna located in free space above ground. The solution is a moment method solution. The influence of lossy ground is taken into account via equivalent images due to Popovic, and the currents of images are expressed by the source current. The dielectric coating is modeled by

Xianshan Li; Khalil El Khamlichi Drissi; Françoise Paladian

2004-01-01

324

6, 72077233, 2006 Vertical distribution  

E-print Network

cloud sides. Inversion of measurements from the cloud sides requires rigorous understanding of10 the 3 cloud fields generated by a simple stochastic cloud model with the prescribed vertically resolved values of the droplet effective radius. The retrieval algorithm is based on the Bayesian theorem that com

Paris-Sud XI, Université de

325

Vertical axis wind turbine development  

Microsoft Academic Search

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

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

1979-01-01

326

Experimental Results on Gravity Driven Fully Condensing Flows in Vertical Tubes, their Agreement with Theory, and their Differences with Shear Driven Flows' Boundary-  

E-print Network

1 Experimental Results on Gravity Driven Fully Condensing Flows in Vertical Tubes heat transfer correlation for a specific annular condensation flow regime inside a vertical tube. For fully condensing flows of pure vapor (FC-72) inside a vertical cylindrical tube of 6.6 mm diameter and 0

Narain, Amitabh

327

Vertical feed stick wood fuel burning furnace system  

DOEpatents

A stove or furnace for efficient combustion of wood fuel includes a vertical feed combustion chamber (15) for receiving and supporting wood fuel in a vertical attitude or stack. A major upper portion of the combustion chamber column comprises a water jacket (14) for coupling to a source of water or heat transfer fluid for convection circulation of the fluid. The locus (31) of wood fuel combustion is thereby confined to the refractory base of the combustion chamber. A flue gas propagation delay channel (34) extending laterally from the base of the chamber affords delayed travel time in a high temperature refractory environment sufficient to assure substantially complete combustion of the gaseous products of wood burning with forced air prior to extraction of heat in heat exchanger (16). Induced draft draws the fuel gas and air mixture laterally through the combustion chamber and refractory high temperature zone to the heat exchanger and flue. Also included are active sources of forced air and induced draft, multiple circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

Hill, Richard C. (Orono, ME)

1982-01-01

328

Numerical and Experimental Investigations for Effect of Gravity to the Heat Transfer and Fluid Flow Phenomena of Microchannel Heat Exchangers  

Microsoft Academic Search

For both numerically and experimentally, effect of gravity on the heat transfer and fluid flow phenomenon of microchannel heat exchangers was presented. The influence was determined by two cases: one with horizontal channels, the other with vertical channels. For vertical channels, the hot water is flowing upward which is against the gravitational field, while the cold water is flowing downward

Thanhtrung Dang; Ngoctan Tran; Jyh-tong Teng; Ho Chi Minh

2012-01-01

329

The budgets of heat and salinity in NEMO M. Hieronymus  

E-print Network

for this are that the resolved heat advection is downward above 2000 m, and that geothermal heating is, in fact, a major heat Elsevier Ltd. All rights reserved. 1. Introduction How do the vertical heat fluxes balance in the ocean processes. Wolfe et al. (2008) found that in eddy resolving simulations with the Massa- chusetts Institute

Nycander, Jonas

330

Graphene vertical hot-electron terahertz detectors  

NASA Astrophysics Data System (ADS)

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 A3B5 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.

Ryzhii, V.; Satou, A.; Otsuji, T.; Ryzhii, M.; Mitin, V.; Shur, M. S.

2014-09-01

331

Saturated flow boiling of water in a vertical small diameter tube  

Microsoft Academic Search

The characteristics of flow boiling heat transfer of water in a vertical tube with a 1.45 mm diameter, which is less than the Laplace constant, are experimentally studied under atmospheric pressure and forced flow condition. Local heat transfer coefficients are measured in a range of mass fluxes from 23.4 to 152.7 kg\\/m2s, heat fluxes from 10 to 715 kW\\/m2 and

Baduge Sumith; Fumito Kaminaga; Kunihito Matsumura

2003-01-01

332

Effects of a wavy interface on steam-air condensation on a vertical surface  

Microsoft Academic Search

A correlation of vapor-side heat transfer coefficients is proposed for condensation of a steam-air mixture on a vertical surface. The correlation is based on the analogy between heat and mass transfer and includes the effects of the wavy interface between a condensate film and bulk vapor on the condensation. For a film Reynolds number less than 350, the vapor-side heat

S. K. Park; M. H. Kim; K. J. Yoo

1997-01-01

333

Kinematic Fitting of Detached Vertices  

SciTech Connect

The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

Paul Mattione

2007-05-01

334

Vertically Integrated Circuits at Fermilab  

SciTech Connect

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.

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

2009-01-01

335

5-Foot Vertical Wind Tunnel  

NASA Technical Reports Server (NTRS)

Construction of 5-Foot Vertical Wind Tunnel. The 5-Foot Vertical Wind Tunnel was built to study spinning characteristics of aircraft. It was an open throat tunnel capable of a maximum speed of 80 mph. NACA engineer Charles H. Zimmerman designed the tunnel starting in 1928. Construction was completed in December 1929. It was one of two tunnels which replaced the original Atmospheric Wind Tunnel (The other was the 7x10-Foot Wind Tunnel.). In NACA TR 387 (p. 499), Carl Wenzinger and Thomas Harris report that 'the tunnel passages are constructed of 1/8-inch sheet iron, stiffened with angle iron and bolted together at the corners. The over-all dimensions are: Height 31 feet 2 inches; length, 20 feet 3 inches; width, 10 feet 3 inches.' The tunnel was partially constructed in the Langley hanger as indicated by the aircraft in the background. Published in NACA TR 387, 'The Vertical Wind Tunnel of the National Advisory Committee for Aeronautics,' by Carl J. Wenzinger and Thomas A. Harris, 1931.

1930-01-01

336

Mathematical simulation of lithium bromide solution laminar falling film evaporation in vertical tube  

NASA Astrophysics Data System (ADS)

For utilization of the residual heat of flue gas to drive the absorption chillers, a lithium-bromide falling film in vertical tube type generator is presented. A mathematical model was developed to simulate the heat and mass coupled problem of laminar falling film evaporation in vertical tube. In the model, the factor of mass transfer was taken into account in heat transfer performance calculation. The temperature and concentration fields were calculated. Some tests were conducted for the factors such as Re number, heating flux, the inlet concentration and operating pressure which can affect the heat and mass transfer performance in laminar falling film evaporation. The heat transfer performance is enhanced with the increasing of heat flux. An increasing inlet concentration can weaken the heat transfer performance. The operating pressure hardly affects on heat and mass transfer. The bigger inlet Re number means weaker heat transfer effects and stronger mass transfer. The mass transfer obviously restrains the heat transfer in the falling film solution. The relation between dimensionless heat transfer coefficient and the inlet Re number is obtained.

Shi, Chengming; Wang, Yang; Hu, Huili; Yang, Ying

2010-06-01

337

Experimental investigation of flow regimes and oscillatory phenomena of condensing steam in a single vertical annular passage  

Microsoft Academic Search

Steam condensing in vertical annular passages experiences regular flow and pressure oscillations. An experimental program with a counterflow condensing heat exchanger with flow visualization was designed to obtain the flow and pressure data along with photographic and video records of condensing steam in vertical upflow in annular passages. The experimental results were compared to the literature on condensation oscillations.From the

B. D. Boyer; G. E. Robinson; T. G. Hughes

1995-01-01

338

Vertical Integration and Technology: Theory and Evidence  

E-print Network

We study the determinants of vertical integration. We first derive a number of predictions regarding the relationship between technology intensity and vertical integration from a simple incomplete contracts model. Then, ...

Acemoglu, Daron

339

Vertical silicon nanowire arrays for gas sensing  

E-print Network

The goal of this research was to fabricate and characterize vertically aligned silicon nanowire gas sensors. Silicon nanowires are very attractive for gas sensing applications and vertically aligned silicon nanowires are ...

Zhao, Hangbo

2014-01-01

340

Fast reactor power plant design having heat pipe heat exchanger  

DOEpatents

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.

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

1985-01-01

341

Fast reactor power plant design having heat pipe heat exchanger  

DOEpatents

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.

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

1984-08-30

342

Wideband Circularly Polarized Vertical Patch Antenna  

Microsoft Academic Search

A compact circularly polarized (CP) vertical patch antenna is presented that employs a microstrip to slot-line transition for a wideband operation. The antenna is composed of two vertical patches, which are shaped as helix to obtain a broadband CP performance. The loop structure and the vertical overlap configuration lead to significant size reduction as much as 48% when compared to

Ze-Hai Wu; Edward Kai-Ning Yung

2008-01-01

343

Vertical Lift - Not Just For Terrestrial Flight  

NASA Technical Reports Server (NTRS)

Autonomous vertical lift vehicles hold considerable potential for supporting planetary science and exploration missions. This paper discusses several technical aspects of vertical lift planetary aerial vehicles in general, and specifically addresses technical challenges and work to date examining notional vertical lift vehicles for Mars, Titan, and Venus exploration.

Young, Larry A

2000-01-01

344

An experimental investigation of bubble growth and detachment in vertical upflow and downflow boiling  

Microsoft Academic Search

A visual study of vapor bubble growth and departure in vertical upflow and downflow forced convection boiling is presented. A vertical flow boiling facility was constructed with a transparent, electrically-heated test section in which the ebullition process could be observed. High-speed digital images of flow boiling phenomena were obtained, which were used to measure bubble growth, departure diameters, and lift-off

G. E. Thorncroft; J. F. Klausner; R. Mei

1998-01-01

345

Entropy generation in flow field subjected to a porous block in a vertical channel  

Microsoft Academic Search

Entropy generation in the flow field subjected to a porous block situated in a vertical channel is examined. The effects of\\u000a channel inlet port height (vertical height between channel inlet port and the block center), porosity, and block aspect ratio\\u000a on the entropy generation rate due to fluid friction and heat transfer in the fluid are examined. The governing equations

S. Z. Shuja; Bekir Sami Yilbas; A. Jamal

2008-01-01

346

Vertical feed stick wood fuel burning furnace system  

DOEpatents

A new and improved stove or furnace for efficient combustion of wood fuel including a vertical feed combustion chamber for receiving and supporting wood fuel in a vertical attitude or stack, a major upper portion of the combustion chamber column comprising a water jacket for coupling to a source of water or heat transfer fluid and for convection circulation of the fluid for confining the locus of wood fuel combustion to the bottom of the vertical gravity feed combustion chamber. A flue gas propagation delay channel extending from the laterally directed draft outlet affords delayed travel time in a high temperature environment to assure substantially complete combustion of the gaseous products of wood burning with forced air as an actively induced draft draws the fuel gas and air mixture laterally through the combustion and high temperature zone. Active sources of forced air and induced draft are included, multiple use and circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

Hill, Richard C. (Orono, ME)

1984-01-01

347

Neighbourly polytopes with few vertices  

SciTech Connect

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.

Devyatov, Rostislav A [M. V. Lomonosov Moscow State University, Faculty of Mechanics and Mathematics, Moscow (Russian Federation)

2011-10-31

348

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

Microsoft Academic Search

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

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

2008-01-01

349

Heat Illness  

MedlinePLUS

... dangerous levels and you can develop a heat illness. Most heat illnesses occur from staying out in ... Heat-related illnesses include Heatstroke - a life-threatening illness in which body temperature may rise above 106° ...

350

FFTF vertical sodium storage tank preliminary thermal analysis  

SciTech Connect

In the FFTF Shutdown Program, sodium from the primary and secondary heat transport loops, Interim Decay Storage (IDS), and Fuel Storage Facility (FSF) will be transferred to four large storage tanks for temporary storage. Three of the storage tanks will be cylindrical vertical tanks having a diameter of 28 feet, height of 22 feet and fabricated from carbon steel. The fourth tank is a horizontal cylindrical tank but is not the subject of this report. The storage tanks will be located near the FFTF in the 400 Area and rest on a steel-lined concrete slab in an enclosed building. The purpose of this work is to document the thermal analyses that were performed to ensure that the vertical FFTF sodium storage tank design is feasible from a thermal standpoint. The key criterion for this analysis is the time to heat up the storage tank containing frozen sodium at ambient temperature to 400 F. Normal operating conditions include an ambient temperature range of 32 F to 120 F. A key parameter in the evaluation of the sodium storage tank is the type of insulation. The baseline case assumed six inches of calcium silicate insulation. An alternate case assumed refractory fiber (Cerablanket) insulation also with a thickness of six inches. Both cases assumed a total electrical trace heat load of 60 kW, with 24 kW evenly distributed on the bottom head and 36 kW evenly distributed on the tank side wall.

Irwin, J.J.

1995-02-21

351

Solar and ground source heat-pump system  

Microsoft Academic Search

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

Yuehong Bi; Tingwei Guo; Liang Zhang; Lingen Chen

2004-01-01

352

Low-Frequency Equatorial Waves in Vertically Sheared Zonal Flow. Part II: Unstable Waves.  

NASA Astrophysics Data System (ADS)

The stability of equatorial Rossby waves in the presence of mean flow vertical shear and moisture convergence-induced heating is investigated with a primitive equation model on an equatorial plane.A vertical shear alone can destabilize equatorial Rossby waves by feeding mean flow available potential energy to the waves. This energy transfer necessitates unstable waves' constant phase lines tilt both horizontally (eastward with latitude) and vertically (against the shear). The preferred most unstable wavelength increases with increasing vertical shear and with decreasing heating intensity, ranging typically from 3000 to 5000 km. The instability strongly depends on meridional variation of the vertical shear. A broader meridional extent of the shear allows a faster growth and a less-trapped meridional structure. When the shear is asymmetric relative to the equator, the unstable Rossby wave is constrained to the hemisphere where the shear is prominent. Without boundary layer friction the Rossby wave instability does not depend on the sign of the vertical shear, whereas in the presence of the boundary layer, the moist Rossby wave instability is remarkably enhanced (suppressed) by easterly (westerly) vertical shears. This results from the fact that an easterly shear confines the wave to the lower level, generating a stronger Ekman-pumping-induced heating and an enhanced meridional heat flux, both of which reinforce the instability.The moist baroclinic instability is a mechanism by which westward propagating rotational waves (Rossby and Yanai waves) can be destabilized, whereas Kelvin waves cannot. This is because the transfer of mean potential energy to eddy requires significant magnitude of barotropic motion. The latter is a modified Rossby wave and can be resonantly excited only by the westward propagating rotational waves. The common features and differences of the equatorial Rossby wave instability and midlatitude baroclinic instability, as well as the implications of the results are discussed.

Xie, Xiaosu; Wang, Bin

1996-12-01

353

Vertical profiles of condensation nuclei  

NASA Technical Reports Server (NTRS)

Condensation nuclei measurements using a low supersaturation (about 10%) thermal gradient diffusion cloud chamber (TGDCC) and a high supersaturation (about 200%) expansion type instrument were compared on a series of three balloon flights over Laramie, Wyoming. In general, the two instruments produced similar vertical profiles but some discrepancies remain unexplained. Agreement between the two would indicate that the low supersaturations used in the TGDCC were still large enough to cause the instrument to count essentially all of the particles present. The TGDCC condensation nuclei (CN) counter was flown at several sites in both the Northern and Southern Hemispheres. The results indicate the existence of a relative maximum in the CN mixing ratio associated with the upper equatorial troposphere and what appears to be a worldwide constant mixing ratio of CN above 20-25 km.

Rosen, J. M.; Hofmann, D. J.; Kaselau, K. H.

1978-01-01

354

Carbothermic reduction with parallel heat sources  

DOEpatents

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.

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

1984-12-04

355

Premixed flame impingement heat transfer with induced swirl  

Microsoft Academic Search

Experiments were performed to study the heat transfer characteristics of a swirling premixed flame impinging vertically normal to a horizontal plate. The effects of Reynolds number (Re), equivalence ratio (?) and nozzle-to-plate distance (H) on the heat flux were examined. Comparisons were also made between the heat transfer behaviors of the swirling premixed flame (SPF) with a non-swirling premixed flame

D. D. Luo; H. S. Zhen; C. W. Leung; C. S. Cheung

2010-01-01

356

Pribnow, Kinoshita & Stein -1 -ODP Heat Flow Report Daniel Pribnow  

E-print Network

associated with fluid flow and gas hydrate formation. To calculate heat flow, temperatures with depth Heat Flow Report heat flow is the product of the vertical gradient of the temperature, which with temperature probes on the JOIDES Resolution during legs 101-180 are reanalyzed in a standard systematic manner

357

Intensification of heat transfer in flash film evaporators  

Microsoft Academic Search

The horizontal arrangement of the panels in the evaporator was selected after analysis of the process of heat transfer in different sections of the heat-exchange elements of known panel-type vertical gravity film evaporators, which showed a low local heat transfer in the first upper section of the panel (because of the instability of the film flow of the solution being

L. P. Pertsev; P. E. Novikov; E. P. Novikov; P. A. Kapustenko

1992-01-01

358

On Heat Flow Singularities Over Mid-Ocean Ridges  

Microsoft Academic Search

Carrent interpretations of heat flow values within the framework of plate tectonics concepts fail to reproduce the available observations for the oceanic ridge crests and give heat flow singularities. A new mathematically tractable theory of vertical intrusion (using a nonuniform temperature distribution at the ridge crest) has been constructed that shows a reasonable fit between predicted and observed heat flows.

E. A. Lubimova; V. N. Nikitina

1975-01-01

359

Technical Note Theoretical analysis of film condensation heat transfer  

E-print Network

. In the International Journal of Heat and Mass Transfer 45 (2002) 2829­2842 wwwTechnical Note Theoretical analysis of film condensation heat transfer inside vertical mini of the inlet vapor flow rates, the inlet subcooling, and the channel size on the heat transfer coefficients

Zhao, Tianshou

360

Experimental natural convection on vertical surfaces for building integrated photovoltaic (BIPV) applications  

SciTech Connect

An experimental study on natural convection in an open channel is carried out in order to investigate the effect of the geometrical configuration of heat sources on the heat transfer behaviour. To this aim, a series of vertical heaters are cooled by natural convection of air flowing between two parallel walls. The objective of the work is to investigate the physical mechanisms which influence the thermal behaviour of a double-skin photovoltaic (PV) facade. This results in a better understanding of the related phenomena and infers useful engineering information for controlling the energy transfers from the environment to the PV surfaces and from the PV surfaces to the building. Furthermore increasing the heat transfer rate from the PV surfaces increases the conversion efficiency of the PV modules since they operate better as their temperature is lower. The test section consists in a double vertical wall, 2 m high, and each wall is constituted by 10 different heating modules 0.2 m high. The heater arrangement simulates, at a reduced scale, the presence of a series of vertical PV modules. The heat flux at the wall ranges from 75 to 200 W/m{sup 2}. In this study, the heated section is 1.6 m in height, preceded by an adiabatic of 0.4 m in height. Different heating configurations are analyzed, including the uniform heating mode and two different configurations of non uniform, alternate heating. The experimental procedure allows the wall surface temperature, local heat transfer coefficient and local and average Nusselt numbers to be inferred. The experimental evidences show that the proper selection of the separating distance and heating configuration can noticeably decrease the surface temperatures and hence enhance the conversion efficiency of PV modules. (author)

Fossa, M. [Diptem, Universita di Genova, Via Opera Pia 15a, 16145 Genova (Italy); Menezo, C. [Centre de Thermique de Lyon (CETHIL UMR 5008, CNRS-INSA Lyon - Universite Lyon 1), Bat. Sadi Carnot, INSA de Lyon, 20 av. A. Einstein, 69 621 Villeurbanne Cedex (France); Leonardi, E. [School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney NSW 2052 (Australia)

2008-02-15

361

Experimental study on the condensation of ethanol-water mixtures on vertical tube  

NASA Astrophysics Data System (ADS)

The condensation heat transfer of the ethanol-water mixtures on the vertical tube over a wide range of ethanol concentrations was investigated. The condensation curves of the heat flux and the heat transfer coefficients revealed nonlinear characteristics and had peak values, with respect to the change of the vapor-to-surface temperature difference. This characteristic applies to all ethanol concentrations under all experimental conditions. With the decrease of the ethanol concentrations, the condensation heat transfer coefficient increased notably, especially when the ethanol concentration was very low. The maximum heat transfer coefficient of the vapor mixtures increased to 9 times as compared with that of pure steam at ethanol vapor mass concentration of 1%. With the increase of the ethanol concentrations, the condensation heat transfer coefficient decreased accordingly. When the ethanol concentration reached 50%, the heat transfer coefficient was smaller than that of the pure steam.

Li, Yang; Yan, Junjie; Qiao, Lei; Hu, Shenhua

2008-03-01

362

Characteristics of vertical climbing in African apes  

Microsoft Academic Search

The evolution of bipedalism is a key event in the transition from apes to early hominids. Vertical climbing has been proposed\\u000a to be the critical locomotor behaviour preadaptive to habitual bipedalism, although quantitative data about vertical climbing\\u000a in nonhuman primates are scarce. This study focuses on 3D-kinematics of vertical climbing in different hominoid species in\\u000a zoos. Emphasis is laid on

Karin Isler

2002-01-01

363

Segmented heat sink device  

SciTech Connect

A heat sink is described having a four sector configuration of four duplicate square baseplate units each placed in close non-touching juxtaposition to form a central orifice area for diverting air flow across radially oriented fins outward past the periphery of each sector, the combination comprising: the four duplicate square baseplate units holding vertical fin elements of variable length to form the four sectors and where the inner apex of each sector includes an area devoid of fins to form the central orifice area.

Gabuzda, P.G.

1987-07-28

364

Heating Safety  

MedlinePLUS

... for heating. • Have a qualified professional install stationary space heating equipment, water heaters or central heating equipment according to the local codes and manufacturer’s instructions. • Maintain heating ... • For fuel burning space heaters, always use the proper fuel as specified ...

365

Heat pumps  

NSDL National Science Digital Library

What electric heating system is the most efficient in moderate climates? This reading, part of a series about the future of energy, introduces students to the modern heat pump. Students read about the efficiency of heat pumps and the three types currently being used in homes. A simple explanation of how a heat pump works is offered. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

366

A visualization comparison of convective flow boiling heat transfer augmentation devices  

E-print Network

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...

Lundy, Brian Franklin

2012-06-07

367

Boiling characteristics in small vertical tubes with closed bottom for nanofluids and nanoparticle-suspensions  

Microsoft Academic Search

An experimental study was carried out to understand the nucleate boiling characteristics and the critical heat flux (CHF)\\u000a of water, the water based nanofluids and the water based nanoparticle-suspensions in vertical small heated tubes with a closed\\u000a bottom. Here, the nanofluids consisted of the base liquid, the CuO nanoparticles and the surfactant. The nanoparticle-suspensions\\u000a consisted of the base liquid and

Lv Lun-Chun; Liu Zhen-Hua

2008-01-01

368

Effects of heat exchanger tube parameters on nucleate pool boiling heat transfer in a scaled IRWST  

SciTech Connect

In an effort to determine the combined effects of major parameters of heat exchanger tubes on the nucleate pool boiling heat transfer in the scaled in-containment refueling water storage tank (IRWST), a total of 1,966 data for q{double_prime} versus {Delta}T has been obtained using various combinations of tube diameters, surface roughness, and tube orientations. The experimental results show that (1) increased surface roughness enhances heat transfer for both horizontal and vertical tubes, (2) the two heat transfer mechanisms, i.e., enhanced heat transfer due to liquid agitation by bubbles generated and reduced heat transfer by the formation of large vapor slugs and bubble coalescence are different in two regions of low heat fluxes (q{double_prime} {le} 50 kW/m{sup 2}) and high heat fluxes (q{double_prime} > 50 kW/m{sup 2}) depending on the orientation of tubes and the degree of surface roughness, and (3) the heat transfer rate decreases as the tube diameter is increased for both horizontal and vertical tubes, but the effect of tube diameter on the nucleate pool boiling heat transfer for vertical tubes is greater than that for horizontal tubes. Two empirical heat transfer correlations for q{double_prime}, one for horizontal tubes and the other for vertical tubes, are obtained in terms of surface roughness ({var_epsilon}) and tube diameter (D). In addition, a simple empirical correlation for nucleate pool boiling heat transfer coefficient (h{sub b}) is obtained as a function of heat flux (q{double_prime}) only.

Chun, M.H.; Kang, M.G. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Nuclear Engineering

1996-08-01

369

Vertical Structure of NGC 4631  

NASA Astrophysics Data System (ADS)

We present a deep CCD imaging in B and V bands which allows us to analyze the vertical structure of NGC 4631. We derive the scale heights of the thin and thick disks at a variety of positions along the major axis of the disk. The scale heights of the thin disk are nearly constant while those of the thick disk tend to increase with increasing galactocentric distance. The mean scale heights of the thin disk derived from B and V images are similar to each other (˜450 pc). Instead, those of the thick disk show a strong east-west asymmetry which is caused by the diffuse stellar emission that is most prominent in the north west regions above the disk plane. The ratio of scale heights (z_{thick}/z_{thin}) is about 2.5 in the east side of the disk. However, this ratio is greater than 4 for the thick disk above the disk plane in the west side of the galaxy.

Ann, Hong Bae; Seo, Mira Seo; Baek, Su-Ja

2011-02-01

370

Horizontal and vertical mixing by surface-trapped eddies  

NASA Astrophysics Data System (ADS)

Ocean eddies play a critical role in modulating the vertical transport of heat, carbon, and nutrients, with important implications for biological processes and climate change. Typically, eddies are generated by instability of the mean flow profile, which often involves surface shears that interact with the interior potential vorticity gradient to excite surface-trapped modes with an exponentially decaying vertical profile. In this study, we exploit the observation that the potential vorticity (PV) inversion problem for a general mean state can be decomposed into a part forced by surface boundary conditions and a part forced by the interior PV distribution. This allows for a convenient categorization of the mean state into Charney-type --- in which surface shears interact with a background meridional PV gradient --- or Phillips-type, which is unstable when there exists an inflection point in the mean PV profile. Within this framework, we examine idealized Charney, Phillips and mixed mean states with the goal of elucidating the equilibration, vertical structure, and transport properties of surface-trapped eddies.

Keating, S. R.; Smith, K.

2012-12-01

371

Local flow characteristics of subcooled boiling flow of water in a vertical concentric annulus  

Microsoft Academic Search

The radial profiles of local void fraction and velocities of both phases were measured in subcooled boiling flow of water in a vertical concentric annulus with a heated inner tube. A two-conductivity probe technique was used for the measurements of local void fraction and vapor velocity and a Pitot tube method was applied to measure the local liquid velocity. Measurements

T. H. Lee; G. C. Park; D. J. Lee

2002-01-01

372

Determination of boundary-layer parameters using a vertical gill anemometer  

Microsoft Academic Search

The paper presents a simple method to compute the stability parameter Z\\/L and boundary-layer parameters such as friction velocity U * and surface heat flux Q 0 on an operational basis. The method is based on the autocorrelation function of the vertical velocity which is relatively insensitive to averaging times except for very large lag times. Eddy correlation techniques on

P. K. Misra

1979-01-01

373

Natural convection-radiation cooling of a vertical divided vented channel  

Microsoft Academic Search

Purpose – The purpose of this paper is to study the radiation-natural convection interactions in a vertical divided vented channel. The effects of the surface emissivity, the vent opening position and size on the heat transfer and the flow structures inside the channel were studied. Design\\/methodology\\/approach – The governing differential equations are solved by a finite volume method, with adopting

A. Mezrhab; H. Bouali; H. Amaoui; C. Abid

2006-01-01

374

Vertical greening systems and the effect on air flow and temperature on the building envelope  

Microsoft Academic Search

The use of horizontal and vertical greening has an important impact on the thermal performance of buildings and on the effect of the urban environment as well, both in summer and winter. Plants are functioning as a solar filter and prevent the adsorption of heat radiation of building materials extensively. Applying green façades is not a new concept; however it

Katia Perini; Marc Ottelé; A. L. A. Fraaij; E. M. Haas; Rossana Raiteri

2011-01-01

375

MHD free convection flow in open-ended vertical porous channels  

Microsoft Academic Search

Analytical solutions for fully developed MHD natural convection flow in open-ended vertical porous channels are presented. Four fundamental boundary conditions have been investigated and the corresponding fundamental solutions are obtained. These four fundamental boundary conditions are obtained by combining each of the two conditions of having one boundary maintained at uniform heat flux or at uniform wall temperature with each

M. A. Al-Nimr; M. A. Hader

1999-01-01

376

Mixed convection–radiation interaction in a vertical porous channel: Entropy generation  

Microsoft Academic Search

The present work examines analytically the effects of radiation heat transfer on magnetohydrodynamic mixed convection through a vertical channel packed with fluid saturated porous substances. First and Second Laws of thermodynamics are applied to analyze the problem. Special attention is given to entropy generation characteristics and their dependency on the various dimensionless parameters, i.e., Hartmann number (Ha), Plank number (Pl),

Shohel Mahmud; Roydon Andrew Fraser

2003-01-01

377

A New Type of Captive Balloon for Vertical Meteorological Observation in Urban Area  

Microsoft Academic Search

Many meteorological observations in urban area have been made in recent years in order to investigate the mechanism of heat island. However, there are few data of cooling process in urban area. For this purpose, high density observations in both space and time are required. Generally vertical meteorological observations can be made by towers, radars, balloons. These methods are limited

M. Nakamura; S. Sakai; K. Ono

2010-01-01

378

Analysis of the complete condensation in a vertical tube passive condenser  

Microsoft Academic Search

A theoretical analysis on complete condensation in a vertical tube passive condenser was performed. The modified Nusselt model with a correction factor and the Blangetti model for film heat transfer were compared with the experimental data. For the interfacial shear, the effect of mass transfer at the interface was considered. For small film Reynolds number and small interfacial shear conditions,

Seungmin Oh; Shripad T. Revankar

2005-01-01

379

Effects of arsenic n+ contact implants on memory switching in vertical polycrystalline silicon resistors  

Microsoft Academic Search

The effects of arsenic implants, which form the lower and the upper n+ contact regions of the vertical polycrystalline silicon resistor, on memory switching have been investigated. It is shown that switching in devices without the lower n+ contact is initiated due to Joule heating, whereas in devices without the upper n+ contact, it is electronic in nature. These resistors

V. Malhotra

1992-01-01

380

Slug-to-annular regime transitions in R-134a flowing through a vertical duct  

Microsoft Academic Search

Measurements of pressure gradient, local void fraction and interfacial velocity were taken in R-134a flowing through a vertical duct to characterize the transition from slug to fully developed annular flow. The measurements were taken in both heated and adiabatic conditions for two system pressures and two mass flow rates. The adiabatic data showed that droplet entrainment was enhanced at the

P. F Vassallo; T. A Trabold; R Kumar; D. M Considine

2001-01-01

381

Elevated ozone layers and vertical down-mixing over the Lower Fraser Valley, BC  

Microsoft Academic Search

Vertical profiling data, including lidar, are used to illustrate elevated layer development during two days of the Pacific '93 field study. Results indicate that multiple processes may produce layers. The “chimney effect”, where pollutants are vented along the heated sidewalls of the valley, is shown to be important, while evidence is also shown for “convective debris” contributing to elevated layer

I. G. McKendry; D. G. Steyn; J. Lundgren; R. M. Hoff; W. Strapp; K. Anlauf; F. Froude; J. B. Martin; R. M. Banta; L. D. Olivier

1997-01-01

382

Introduction Diel vertical migration occurs when plankton  

E-print Network

Introduction Diel vertical migration occurs when plankton migrate vertically in the water column over a 24 h cycle. Zooplankton typically migrate nocturnally, occupying depths near the hypolimnion during the day and moving into the epilimnion during the evening (Haney 1993). Reverse migration

New Hampshire, University of

383

Sewing string tree vertices with ghosts  

E-print Network

It is shown how to sew string vertices with ghosts at tree level in order to produce new tree vertices using the Group Theoretic approach to String Theory. It is then verified the BRST invariance of the sewn vertex and shown that it has the correct ghost number.

L. Sandoval Jr

1999-09-22

384

Sewing string tree vertices using canonical forms  

E-print Network

We effectively sew two vertices with ghosts in order to obtain a third, composite vertex in the most general case of cycling transformations. In order to do this, we separate the vertices into two parts: a bosonic oscillator part and a ghost oscillator part and write them as canonical forms.

Leonidas Sandoval Jr

2001-04-17

385

Evolution of Mutualistic Symbiosis without Vertical Transmission  

Microsoft Academic Search

Mutualistic symbioses are considered to evolve from parasitic relationships. Vertical transmission, defined as the direct transfer of infection from a parent organism to its progeny, has been suggested as a key factor causing reduction of symbiont virulence and evolution of mutualism. On the other hand, there are several mutualistic associations without vertical transmission, such as those between plants and mycorrhizal

Motomi Genkai-Kato; Norio Yamamura

1999-01-01

386

A Vertically Resolved Planetary Boundary Layer  

NASA Technical Reports Server (NTRS)

Increase of the vertical resolution of the GLAS Fourth Order General Circulation Model (GCM) near the Earth's surface and installation of a new package of parameterization schemes for subgrid-scale physical processes were sought so that the GLAS Model GCM will predict the resolved vertical structure of the planetary boundary layer (PBL) for all grid points.

Helfand, H. M.

1984-01-01

387

Combined Lateral Vertical RESURF (CLAVER) LDMOS structure  

Microsoft Academic Search

In this paper, a unique Combined Lateral Vertical RESURF (CLAVER) LDMOS structure is proposed for breakthrough performance. The structure uses a secondary RESURF design to terminate in the vertical direction to yield a much improved performance trade-off. The proposed device uses standard process steps available in integrated technology platforms to give a breakdown as high as 150 V with ground-breaking

T. Khan; V. Khemka; Ronghua Zhu; Weixiao Huang; Xu Cheng; P. Hui; Muh-ling Ger; B. Grote; P. Rodriquez

2009-01-01

388

Entirely passive heat pipe apparatus capable of operating against gravity  

DOEpatents

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.

Koenig, Daniel R. (Santa Fe, NM)

1982-01-01

389

Origami Multistabilty: From Single Vertices to Metasheets  

E-print Network

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.

Scott Waitukaitis; Rémi Menaut; Bryan Gin-ge Chen; Martin van Hecke

2014-08-07

390

Inclusion of Vertical Dynamics in Vertically-integrated Models for CO2 Storage  

NASA Astrophysics Data System (ADS)

Mathematical models of different complexity are needed to answer a range of questions for geological sequestration of carbon dioxide (CO2). One category of simplified models is based on vertical integration, which reduces the three-dimensional problem to two dimensions. Usually, these models assume that brine and CO2 are in vertical equilibrium. This type of model is useful and accurate for simulation times that are large relative to the time for buoyant segregation. But, vertical-equilibrium models are inappropriate in some situations, for instance, in the early stage of injection, when brine and CO2 have not fully segregated. Therefore, for these situations, the vertical equilibrium assumption needs to be relaxed and vertical dynamics needs to be included in the governing equations. To avoid significant increases of computational effort due to the inclusion of vertical dynamics, a multi-scale algorithm can be constructed where the vertically integrated equations are still used to model the (dominant) horizontal flow processes with the vertical reconstruction included as a dynamic problem. Such an approach allows each vertical column of grid cells to be solved independently, as a one-dimensional problem, during the dynamic reconstruction step. Because the top and bottom boundaries usually correspond to impermeable caprock, the total flow for these one-dimensional problems is zero and counter-current flow driven only by buoyancy and capillarity is involved. Solutions for this kind of problem are relatively simple and require little computational effort. With careful coupling between the vertical calculations and the horizontally integrated equations, an efficient algorithm can be developed to simulate a fairly wide range of problems including those with significant vertical dynamics. When vertical dynamics become insignificant, then usual vertical equilibrium reconstruction is used in the vertically integrated models. This new algorithm provides an intermediate choice in model complexity between full three-dimensional models and vertical-equilibrium two-dimensional models.

Guo, B.; Bandilla, K.; Celia, M. A.

2012-12-01

391

Modeling and experimental study of nucleate boiling on a vertical array of horizontal plain tubes  

SciTech Connect

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)

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

392

Numerical study of natural convection in partially heated rectangular enclosures filled with nanofluids  

Microsoft Academic Search

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

Hakan F. Oztop; Eiyad Abu-Nada

2008-01-01

393

Designer heating  

Microsoft Academic Search

This article discusses the use of hydronic radiant heat as wall units and as systems installed in floors. Described are radiators made in Europe that are said to be superior to convective hydronic heat (the heating principal traditional baseboard units use). The new panel radiators are stocked by only a few US distributors and may cost 20 to 90 percent

1989-01-01

394

Heat hugger  

Microsoft Academic Search

A fireplace insert is disclosed which will efficiently heat the interior of a structure, enable control of fuel burn rate and temperature of heated air directed into the interior structure, and facilitate circulation of the heated air through the interior rooms of the structure via pressure differential created by the forced-air flow through the insert. The unit includes an airtight

Ruegg

1981-01-01

395

A vertically integrated model with vertical dynamics for CO2 storage  

NASA Astrophysics Data System (ADS)

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.

Guo, Bo; Bandilla, Karl W.; Doster, Florian; Keilegavlen, Eirik; Celia, Michael A.

2014-08-01

396

Natural convection of ferrofluids in partially heated square enclosures  

NASA Astrophysics Data System (ADS)

In this study, natural convection of ferrofluid in a partially heated square cavity is numerically investigated. The heater is located to the left vertical wall and the right vertical wall is kept at constant temperature lower than that of the heater. Other walls of the square enclosure are assumed to be adiabatic. Finite element method is utilized to solve the governing equations. The influence of the Rayleigh number (104?Ra?5×105), heater location (0.25H?yh?0.75H), strength of the magnetic dipole (0???2), horizontal and vertical location of the magnetic dipole (-2H?a?-0.5H, 0.2H?b?0.8H) on the fluid flow and heat transfer characteristics are investigated. It is observed that different velocity components within the square cavity are sensitive to the magnetic dipole source strength and its position. The length and size of the recirculation zones adjacent to the heater can be controlled with magnetic dipole strength. Averaged heat transfer increases with decreasing values of horizontal position of the magnetic dipole source. Averaged heat transfer value increases from middle towards both ends of the vertical wall when the vertical location of the dipole source is varied. When the heater location is changed, a symmetrical behavior in the averaged heat transfer plot is observed and the minimum value of the averaged heat transfer is attained when the heater is located at the mid of vertical wall.

Selimefendigil, Fatih; Öztop, Hakan F.; Al-Salem, Khaled

2014-12-01

397

Heat Pipes  

NASA Technical Reports Server (NTRS)

Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

1991-01-01

398

Dust vertical profile impact on global radiative forcing estimation using a coupled chemical-transport-radiative-transfer model  

NASA Astrophysics Data System (ADS)

Atmospheric mineral dust particles exert significant direct radiative forcings and are important drivers of climate and climate change. We used the GEOS-Chem global three-dimensional chemical transport model (CTM) coupled with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rate based on different vertical profiles for April 2006. We attempt to actually quantify the sensitivities of radiative forcing to dust vertical profiles, especially the discrepancies between using realistic and climatological vertical profiles. In these calculations, dust emissions were constrained by observations of aerosol optical depth (AOD). The coupled calculations utilizing a more realistic dust vertical profile simulated by GEOS-Chem minimize the physical inconsistencies between 3-D CTM aerosol fields and the RTM. The use of GEOS-Chem simulated vertical profile of dust extinction, as opposed to the FLG prescribed vertical profile, leads to greater and more spatially heterogeneous changes in the estimated radiative forcing and heating rate produced by dust. Both changes can be attributed to a different vertical structure between dust and non-dust source regions. Values of the dust vertically resolved AOD per grid level (VRAOD) are much larger in the middle troposphere, though smaller at the surface when the GEOS-Chem simulated vertical profile is used, which leads to a much stronger heating rate in the middle troposphere. Compared to the FLG vertical profile, the use of GEOS-Chem vertical profile reduces the solar radiative forcing at the top of atmosphere (TOA) by approximately 0.2-0.25 W m-2 over the African and Asian dust source regions. While the Infrared (IR) radiative forcing decreases 0.2 W m-2 over African dust belt, it increases 0.06 W m-2 over the Asian dust belt when the GEOS-Chem vertical profile is used. Differences in the solar radiative forcing at the surface between the use of the GEOS-Chem and FLG vertical profiles are most significant over the Gobi desert with a value of about 1.1 W m-2. The radiative forcing effect of dust particles is more pronounced at the surface over the Sahara and Gobi deserts by using FLG vertical profile, while it is less significant over the downwind area of Eastern Asia.

Zhang, L.; Li, Q. B.; Gu, Y.; Liou, K. N.; Meland, B.

2013-07-01

399

Sensible and latent heating of the atmosphere as inferred from DST-6 data  

NASA Technical Reports Server (NTRS)

The average distribution of convective latent heating, boundary layer sensible heat flux, and vertical velocity are determined for the winter 1976 DST period from GLAS model diagnostics. Key features are the regions of intense latent heating over Brazil, Central Africa, and Indonesia; and the regions of strong sensible heating due to air mass modification over the North Atlantic and North Pacific Oceans.

Herman, G. F.; Schubert, S. D.; Johnson, W. T.

1979-01-01

400

Vertical Vegetation Structure Below Ground: Scaling from Root to Globe  

E-print Network

exhibit a vertical structure that responds to resources that have a strong vertical dimension, light aboveVertical Vegetation Structure Below Ground: Scaling from Root to Globe H. Jochen Schenk So sind,there ought to be predictable relation- ships between vertical vegetation structure and the vertical

Schenk, H. Jochen

401

Experimental thermal performance study of an inclined heat pipe heat exchanger operating in high humid tropical HVAC systems  

Microsoft Academic Search

In an earlier paper [Y.H. Yau, Application of a heat pipe heat exchanger to dehumidification enhancement in tropical HVAC systems – a baseline performance characteristics study, International Journal of Thermal Sciences 46 (2) (2007) 164–171], the author had established the baseline performance characteristics of the eight-row wickless heat pipe heat exchanger (HPHX) for a vertical configuration under a range of

Y. H. Yau

2007-01-01

402

Performance analysis of a solar-assisted ground-source heat pump system for greenhouse heating: an experimental study  

Microsoft Academic Search

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

Onder Ozgener; Arif Hepbasli

2005-01-01

403

Preliminary analysis of heat pipe heat exchangers for heat recovery  

Microsoft Academic Search

A preliminary analysis of fin tube heat pipe heat exchangers for air-to-air heat recovery was conducted. The analysis uses conventional heat exchanger design techniques and a new heat pipe design technique which includes probabilistic design of artery wick heat pipes. The heat transfer capability of the heat pipes may be matched with that of the finned tubes in order to

J. O. Amode; K. T. Feldman

1975-01-01

404

Low gravity exothermic heating/cooling apparatus  

NASA Technical Reports Server (NTRS)

A low gravity exothermic heating/cooling apparatus is disclosed for processing materials in space which includes an insulated casing and a sample support carried within the casing which support a sample container. An exothermic heat source includes a plurality of segments of exothermic material stacked one upon another to produce a desired temperature profile when ignited. The sample container is arranged within the core of the stacked exothermic heating material. Igniters are spaced vertically along the axis of the heating material to ignite the exothermic material at spaced points to provide total rapid burn and release of heat. To rapidly cool and quench the heat, a source of liquid carbon dixoide is provided which is conveyed through a conduit and a metering orifice into a distribution manifold where the carbon dioxide is gasified and dispersed around the exothermic heating material and the sample container via tubes for rapidly cooling the material sample.

Poorman, R. M. (inventor)

1985-01-01

405

Similitude modeling of natural convection heat transfer through an aperture in passive solar heated buildings  

NASA Astrophysics Data System (ADS)

An experimental study of natural convection heat transfer through a doorway in a two room passive solar heated building is described. Similitude modeling was the method used to measure natural convection heat transfer coefficients (h/sub NC/) in a model geometrically scaled down by a factor of 5. Freon gas was used as the working fluid to obtain dynamic similarity within the model. A temperature difference was maintained between the two rooms by a heated vertical wall which simulated a Trombe wall in one room, and by a cooled vertical wall which simulated a thermal storage wall in the other room. Heat transfer through the doorway was measured as a function of a characteristic temperature differential and the geometry of the doorway.

Weber, D. D.

1980-06-01

406

Vertical wind estimation from horizontal wind measurements  

NASA Technical Reports Server (NTRS)

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.

Vicroy, Dan D.

1994-01-01

407

Continuous Growth of Vertically Aligned Carbon Nanotubes  

E-print Network

Vertically aligned carbon nanotubes (VACNTs), sometimes called forests or carpets, are a promising material due to their unique physical and scale-dependent physical properties [1-3]. Continuous production of VACNTs is ...

Guzman de Villoria, R.

408

On the vertical excitation energy of cyclopentadiene  

NASA Astrophysics Data System (ADS)

The vertical excitation energy for the lowest valence ???* transition of cyclopentadiene is investigated. Using a combination of high-level theoretical methods and spectroscopic simulations, the vertical separation at the ground state geometry is estimated to be 5.43±0.05 eV. This value is intermediate between those calculated with coupled-cluster and multireference perturbation theory methods and is about 0.13 eV higher than the observed maximum in the absorption profile.

Bomble, Yannick J.; Sattelmeyer, Kurt W.; Stanton, John F.; Gauss, Jürgen

2004-09-01

409

Natural convection from heated room surfaces  

Microsoft Academic Search

Current convective heat transfer coefficients (CHTC's) for internal room surfaces have, in most cases, been based upon data for small, free-edge heated plates. An extensive survey of CHTC data has shown that a very wide variation exists in CHTC values for vertical and horizontal surfaces. For example, a CHTC value in the range 1–6 W m?2 K?1 has been obtained

H. B. Awbi; A. Hatton

1999-01-01

410

[Is the sense of verticality vestibular?].  

PubMed

The vestibular system constitutes an inertial sensor, which detects linear (otoliths) and angular (semicircular canals) accelerations of the head in the three dimensions. The otoliths are specialized in the detection of linear accelerations and can be used by the brain as a "plumb line" coding earth gravity acceleration (direction). This property of otolithic system suggested that the sense of verticality is supported by the vestibular system. The preeminence of vestibular involvement in the sense of verticality stated in the 1900s was progressively supplanted by the notion of internal models of verticality. The internal models of verticality involve rules and properties of integration of vestibular graviception, somaesthesic graviception, and vision. The construction of a mental representation of verticality was mainly modeled as a bottom-up organization integrating visual, somatosensory and vestibular information without any cognitive modulations. Recent studies reported that the construction of internal models of verticality is not an automatic multi-sensory integration process but corresponds to more complex mechanisms including top-down influences such as awareness of body orientation or spatial representations. PMID:23856176

Barra, J; Pérennou, D

2013-06-01

411

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2012 CFR

...to the horizontal plane. The vertical angle, represented as ?...the horizontal plane. The vertical plane radiation characteristic...computing radiation in the vertical plane, unless the applicant...formula for a particular type of antenna. If a special formula...

2012-10-01

412

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2010 CFR

...to the horizontal plane. The vertical angle, represented as ?...the horizontal plane. The vertical plane radiation characteristic...computing radiation in the vertical plane, unless the applicant...formula for a particular type of antenna. If a special formula...

2010-10-01

413

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2011 CFR

...to the horizontal plane. The vertical angle, represented as ?...the horizontal plane. The vertical plane radiation characteristic...computing radiation in the vertical plane, unless the applicant...formula for a particular type of antenna. If a special formula...

2011-10-01

414

47 CFR 73.160 - Vertical plane radiation characteristics, f(?).  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

2013-10-01

415

Low-Frequency Equatorial Waves in Vertically Sheared Zonal Flow. Part I: Stable Waves.  

NASA Astrophysics Data System (ADS)

The mechanism by which a vertically sheared zonal flow affects large-scale, low-frequency equatorial waves is investigated with two-level equatorial,-plane and spherical coordinates models.Vertical shears couple barolinic and barotropic components of equatorial wave motion, affecting significantly the Rossby wave and westward propagating Yanai wave but not the Kelvin wave. This difference results from the fact that the barotropic component is a modified Rossby mode and can be resonantly excited only by westward propagating internal waves. The barotropic components emanate poleward into the extratropics with a pronounced amplitude, while the baroclinic components remain equatorially trapped. A westerly vertical shear favors the trapping of Rossby and Yanai waves in the upper troposphere, whereas an easterly shear tends to confine them in the lower troposphere. As such, their westward propagation is slowed down by both westerly and easterly shears. When the strength of the vertical shear varies with latitude, both the vertical modes are locally enhanced in the latitudes of strong shear.The theory suggests that the vertical shear plays an essential role in emanation of heating-induced internal equatorial Rossby waves into the extratropics with a transformed barotropic structure. It may also be partially responsible for trapping perturbation kinetic energy in the upper-troposphere westerly duct and the lower-troposphere monsoon trough.

Wang, Bin; Xie, Xiaosu

1996-02-01

416

Infrared remote sensing of the vertical and horizontal distribution of clouds  

NASA Technical Reports Server (NTRS)

An algorithm has been developed to derive the horizontal and vertical distribution of clouds from the same set of infrared radiance data used to retrieve atmospheric temperature profiles. The method leads to the determination of the vertical atmospheric temperature structure and the cloud distribution simultaneously, providing information on heat sources and sinks, storage rates and transport phenomena in the atmosphere. Experimental verification of this algorithm was obtained using the 15-micron data measured by the NOAA-VTPR temperature sounder. After correcting for water vapor emission, the results show that the cloud cover derived from 15-micron data is less than that obtained from visible data.

Chahine, M. T.; Haskins, R. D.

1982-01-01

417

Natural convection in a vertical annulus containing water near the density maximum  

SciTech Connect

Steady natural convection of water near the density extremum in a vertical annulus is studied numerically. Results for flow in annuli with aspect ratio 1 {le} A {le} 8 and varying degrees of curvature are given for 10{sup 3} {le} Ra {le} 10{sup 5}. It is shown that both the density distribution parameter R and the annulus curvature K have a strong effect on the steady flow structure and heat transfer in the annulus. A closed-form solution for the vertical flow in a very tall annulus is compared with numerical results for finite-aspect-ratio annuli.

Lin, D.S.; Nansteel, M.W. (Univ. of Pennsylvania, Philadelphia (USA))

1987-11-01

418

Designer heating  

SciTech Connect

This article discusses the use of hydronic radiant heat as wall units and as systems installed in floors. Described are radiators made in Europe that are said to be superior to convective hydronic heat (the heating principal traditional baseboard units use). The new panel radiators are stocked by only a few US distributors and may cost 20 to 90 percent more than for American-style units of equal heating capacity. Because of their attractiveness and custom sizes the units may be mounted on open walls. Also described are advances in radiant floor heating. New systems have improved plastic tubing, more installation options, smarter controls and better edge insulation. The disadvantage in radiant floor heating is that floors may not be covered by heavy carpets or rugs.

Flower, R.G.

1989-03-01

419

How well can we measure the vertical component of the wind speed: Implications for the fluxes of energy and mass  

NASA Astrophysics Data System (ADS)

. Sonic anemometer angle of attack or (co)sine errors were estimated for over 100 combinations of angle of attack and wind direction using an R.M. Young sonic anemometer and a novel technique to measure the true angle of attack and the wind velocity within the turbulent surface layer. Corrections to the vertical wind speed varied from -5% to 37% for all angles of attack and wind directions examined. When applied to eddy covariance data from two Ameriflux sites, the (co)sine error corrections increased the magnitude of CO2 fluxes, sensible heat fluxes, and latent heat fluxes by ca. 10%. A sonic anemometer designed with one pair of transducers aligned with the vertical axis (Applied Technologies, Inc., "Vx" style) was also tested at four angles of attack. Corrections to the vertical wind speed measured using this anemometer were within ± 1% of zero. Sensible heat fluxes measured using the Applied Technologies anemometer were 9% greater than sensible heat fluxes measured using the R.M. Young over grass, and were 15% larger over a forest canopy. These results indicate that sensors with an off-axis transducer orientation, such as the R.M. Young, Gill, and CSAT anemometers, should be redesigned to allow for measurement of the vertical velocity using one pair of vertically aligned transducers, like the "Vx" style Applied Technologies anemometer.

Kochendorfer, J.; Meyers, T. P.; Heuer, M.; Frank, J. M.; Massman, W. J.

2011-12-01

420

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS?  

E-print Network

WHICH HYDRAULIC MODEL TO USE IN VERTICAL FLOW CONSTRUCTED WETLANDS? Ania Morvannoua , Nicolas-equilibrium model, preferential flow path, vertical flow constructed wetlands INTRODUCTION Constructed wetlands (CWs

Paris-Sud XI, Université de

421

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

422

Polar heating in Saturn's thermosphere  

NASA Astrophysics Data System (ADS)

A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982) and auroral H3+ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000). We find that a polar heat source is consistent with both the Smith et al. determination of T?~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004). However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T?~800 K at ~4° N and the auroral temperatures simultaneously. Keywords. Ionosphere (Planetary ionosphere) Magnetospherica physics (Planetary magnetospheres) Meterology and atmospheric dynamics (Thermospheric dynamics)

Smith, C. G. A.; Aylward, A. D.; Miller, S.; Müller-Wodarg, I. C. F.

2005-10-01

423

Characteristics of Vertical Profiles of Reflectivity and Doppler Derived From TRMM Field Campaigns  

NASA Technical Reports Server (NTRS)

The TRMM Precipitation Radar (PR) measures the vertical profile of reflectivity from which the surface rain rate is estimated after attenuation corrections in the 2A21 algorithm. Characteristics of the vertical reflectivity profile is important for various reasons ranging from scientific to instrument algorithms. It is well known that different types of precipitation such as stratiform or convection, have different heating profiles. The vertical profile of reflectivity can provide information on precipitation classification. The vertical reflectivity structure also provides information on precipitation processes such as growth and aggregation. In terms of TRMM algorithms, an independent estimate of the vertical profiles are also extremely important since the PR returns can be attenuated in the rain layer near the surface. Corrections for attenuation are required in the lowest few kilometers, necessitating some assumptions about the rain size distributions and the reflectivity profile below the lowest measurement unaffected by the surface return. Furthermore, some assumptions about the vertical reflectivity profile are required for Ground Validation (GV) radars, since their lowest scan may be 1 or more kilometers above the surface. Statistics on the vertical reflectivity and Doppler structure are presented from the ER-2 Doppler Radar (EDOP) which participated in several TRMM field campaigns (TEFLUN-A, TEFLUN-B, and LBA) and CAMEX-3. The ER-2 aircraft overflew diverse precipitation types during these campaigns. EDOP is an X-band (9.6 GHz) radar for which returns are less attenuated than at the TRMM PR frequency. The EDOP profiles are first corrected for attenuation using the SRT method. The data from all the ER-2 campaigns are then classified by type (convection, stratiform, and other) and then statistics were performed on the vertical reflectivity and Doppler profiles in the form of CFAD's. These CFADs are compared and discussed. The computed CFAD's indicate significant differences as a function of precipitation type and location (hurricane versus non-hurricane, Brazil versus Florida). The implications of these profiles will be discussed.

Starr, David OC. (Technical Monitor); Heymsfield, G.; Belcher, L.; Tian, L.

2002-01-01

424

Measurement of liquid helium heat transfer in a high-speed rotational field and consideration of effect of obstacles blocking channels on the heat transfer  

NASA Astrophysics Data System (ADS)

The heat transfer of liquid helium is measured in a high-speed rotating field. The centrifugal acceleration is in the range of 900-4600 g. Vertical test surfaces with channel are used, as well as horizontal surfaces. Moreover, for the vertical surfaces with channels, heat transfer is investigated with a blocked inlet and outlet. We examine blocking at the orifice channel outlet and the cover channel inlet for the heat transfer. Results show that heat transfer on vertical surfaces and the upward facing horizontal surface can be approximately represented by correlation equations for constant property fluids. Channel gap size and coriolis force do not affect heat transfer. The heat transfer of a horizontal surface facing downward is 1/6- 1/7 of the upward facing surface. The orifices and covers for simulating channel blocking have almost no effect on heat transfer. Thus, obstacles blocking the channels do not affect cooling with helium unless blocking is complete.

Mori, Hideaki; Ogata, Hisanao

425

Heat Transfer  

Microsoft Academic Search

\\u000a We are now stepping into the traditional physical chemistry area known as thermodynamics. Thermodynamics is concerned with a change of the total energy of a system. A system is a body which performs work (–w) or gives away heat (?q); the same body can also receive work (+w) or heat (+q). Notice the sign: when you carry out work or

Predrag-Peter Ilich

426

Heat Problems.  

ERIC Educational Resources Information Center

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)…

Connors, G. Patrick

427

Heat transfer characteristics of an impinging premixed annular flame jet  

Microsoft Academic Search

The heat transfer behaviors of an annular jet flame impinging vertically normal to a flat surface were investigated experimentally. The relationship between the flow\\/flame structure of the annular jet flame and the local heat transfer behavior along the surface was analyzed. Further, the effects of Reynolds number (Re), equivalence ratio (?) and nozzle-to-plate distance (H) on the local and overall

H. S. Zhen; C. W. Leung; C. S. Cheung

428

Heating and Large Scale Dynamics of the Solar Corona  

NASA Technical Reports Server (NTRS)

The effort was concentrated in the areas: coronal heating mechanism, unstructured adaptive grid algorithms, numerical modeling of magnetic reconnection in the MRX experiment: effect of toroidal magnetic field and finite pressure, effect of OHMIC heating and vertical magnetic field, effect of dynamic MESH adaption.

Schnack, Dalton D.

2000-01-01

429

Modelling Heat Transport in Coastal Aquifer Incorporating Tidal Effects  

Microsoft Academic Search

Heat transport has been recognized as a hydrologic tracer to indentify surface water infiltration and the exchange of surface water and groundwater. This paper investigates the heat transport with groundwater movement in coastal aquifers under tidal conditions. The aquifer vertically terminates at coastline with a thin submarine outlet-capping. Firstly, the time- averaged analytical solution of tide-induced groundwater head fluctuations in

Qing-Hua Wu; Gui-Ling Wang; Fa-Wang Zhang; Yu-Qing Xia

2011-01-01

430

Climatology of tropospheric vertical velocity spectra  

NASA Technical Reports Server (NTRS)

Vertical velocity power spectra obtained from Poker Flat, Alaska; Platteville, Colorado; Rhone Delta, France; and Ponape, East Caroline Islands using 50-MHz clear-air radars with vertical beams are given. The spectra were obtained by analyzing the quietest periods from the one-minute-resolution time series for each site. The lengths of available vertical records ranged from as long as 6 months at Poker Flat to about 1 month at Platteville. The quiet-time vertical velocity spectra are shown. Spectral period ranging from 2 minutes to 4 hours is shown on the abscissa and power spectral density is given on the ordinate. The Brunt-Vaisala (B-V) periods (determined from nearby sounding balloons) are indicated. All spectra (except the one from Platteville) exhibit a peak at periods slightly longer than the B-V period, are flat at longer periods, and fall rapidly at periods less than the B-V period. This behavior is expected for a spectrum of internal waves and is very similar to what is observed in the ocean (Eriksen, 1978). The spectral amplitudes vary by only a factor of 2 or 3 about the mean, and show that under quiet conditions vertical velocity spectra from the troposphere are very similar at widely different locations.

Ecklund, W. L.; Gage, K. S.; Balsley, B. B.; Carter, D. A.

1986-01-01

431

Using Exergy Analysis Methodology to Assess the Heating Efficiency of an Electric Heat Pump  

E-print Network

., 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...

Ao, Y.; Duanmu, L.; Shen, S.

2006-01-01

432

Vertical Velocity Measurements in Warm Stratiform Clouds  

NASA Astrophysics Data System (ADS)

Measurements of vertical air motion in warm boundary layer clouds are key for quantitatively describing cloud-scale turbulence and for improving our understanding of cloud and drizzle microphysical processes. Recently, a new technique that produces seamless measurements of vertical air velocity in the cloud and sub-cloud layers for both drizzling and non-drizzling stratocumulus clouds has been developed. The technique combines radar Doppler spectra-based retrievals of vertical air motion in cloud and light drizzle conditions with a novel neural network analysis during heavily drizzling periods. Observations from Doppler lidars are used to characterize sub-cloud velocities and to evaluate the performance of the technique near the cloud base. The technique is applied to several cases of stratiform clouds observed by the ARM Mobile Facility during the Two-Column Aerosol Project (TCAP) campaign in Cape Cod. The observations clearly illustrate coupling of the sub-cloud and cloud layer turbulent structures.

Luke, E. P.; Kollias, P.

2013-12-01

433

Purification process for vertically aligned carbon nanofibers  

NASA Technical Reports Server (NTRS)

Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

2003-01-01

434

Liquid storage tanks under vertical excitation  

SciTech Connect

Until recently, the hydrodynamic effects on liquid storage tanks induced by an earthquake excitation were basically treated for the horizontal component of the earthquake. Recent studies, however, showed that the hydrodynamic effects due to the vertical component of an earthquake may be significant. In these studies the tank is assumed to be fixed at the bottom. This paper is concerned with the hydrodynamic behavior of liquid storage tanks induced by vertical earthquake input excitation. First, the fluid-tank system is treated as a fixed-base system and a simple formula is obtained for the coupled fluid-structure natural frequency. Second, additional interaction effects due to the foundation flexibility on the fluid-tank system are investigated. It is concluded that the foundation flexibility may have a significant effect on the hydrodynamic behavior of the liquid storage tanks under a vertical ground shaking.

Philippacopoulos, A.J.

1985-01-01

435

Capacity Planning for Vertical Search Engines  

E-print Network

Vertical search engines focus on specific slices of content, such as the Web of a single country or the document collection of a large corporation. Despite this, like general open web search engines, they are expensive to maintain, expensive to operate, and hard to design. Because of this, predicting the response time of a vertical search engine is usually done empirically through experimentation, requiring a costly setup. An alternative is to develop a model of the search engine for predicting performance. However, this alternative is of interest only if its predictions are accurate. In this paper we propose a methodology for analyzing the performance of vertical search engines. Applying the proposed methodology, we present a capacity planning model based on a queueing network for search engines with a scale typically suitable for the needs of large corporations. The model is simple and yet reasonably accurate and, in contrast to previous work, considers the imbalance in query service times among homogeneous...

Badue, Claudine; Almeida, Virgilio; Baeza-Yates, Ricardo; Ribeiro-Neto, Berthier; Ziviani, Artur; Ziviani, Nivio

2010-01-01

436

Heat pipe array heat exchanger  

Microsoft Academic Search

A heat exchanger is described for transferring heat between a first fluid and a second fluid in an absorption refrigeration system comprising: a first shell having an inlet for receiving the first fluid at a first elevated temperature and an outlet for discharging the first fluid at a first reduced temperature with the shell defining a free flow path for

Reimann

1987-01-01

437

Fundamental and effective Yang-Mills vertices  

SciTech Connect

Calorons and plane waves within and in between them collectively give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a single caloron in inducing effective local vertices, characterized by powers of h, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.

Hofmann, Ralf [ITP, Universitaet Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany)

2012-09-26

438

CIRSS vertical data integration, San Bernardino study  

NASA Technical Reports Server (NTRS)

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.

Hodson, W.; Christenson, J.; Michel, R. (principal investigators)

1982-01-01

439

Concepts for generating optimum vertical flight profiles  

NASA Technical Reports Server (NTRS)

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.

Sorensen, J. A.

1979-01-01

440

Nanofluid impingement jet heat transfer.  

PubMed

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

Zeitoun, Obida; Ali, Mohamed

2012-01-01

441

Free convection heat and mass transfer with Hall current, Joule heating and thermal diffusion  

Microsoft Academic Search

A boundary layer analysis has been presented to study the combined effects of viscous dissipation, Joule heating, transpiration,\\u000a heat source, thermal diffusion and Hall current on the hydromagnetic free convection and mass transfer flow of an electrically\\u000a conducting, viscous, homogeneous, incompressible fluid past an infinite vertical porous plate. The governing partial differential\\u000a equations of the hydromagnetic free convective boundary layer

Ajay Kumar Singh; Rama Subba Reddy Gorla

2009-01-01

442

Heat pipe heat exchanger for heat recovery in air conditioning  

Microsoft Academic Search

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5

Mostafa A. Abd El-Baky; Mousa M. Mohamed

2007-01-01

443

Corrosive resistant heat exchanger  

DOEpatents

A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

Richlen, Scott L. (Annandale, VA)

1989-01-01

444

Depth aftereffects mediated by vertical disparities: Evidence for vertical disparity driven calibration of extraretinal signals during stereopsis  

Microsoft Academic Search

Perceptual adaptation often results in a repulsive aftereffect: stimuli are seen as biased away from the adaptation stimulus (Blakemore & Sutton, 1969). Here we report the absence of a repulsive aftereffect for a vertical gradient of vertical disparity (or vertical size ratio, VSR). We exposed observers to a binocular stimulus consisting of horizontal lines. This stimulus contains vertical, but not

Philip A. Duke; Ipek Orucb; Haijiang Qi; Benjamin T. Backus

2006-01-01

445

Condensation on the surface of vertical tube placed in a granular layer with different contact wetting angle  

NASA Astrophysics Data System (ADS)

The results of theoretical and experimental studies of heat exchange at condensation of motionless steam on a vertical tube placed in a granular layer with different wetting angle are presented. Theoretical dependencies are obtained for the estimate of heat-exchange intensity, which account for the condensate slip on the surfaces of grains, and their satisfactory agreement with experimental data of the authors is shown.

Shilyaev, M. I.; Bogomolov, A. R.; Petrik, P. T.

2008-06-01

446

Determination of boundary-layer parameters using a vertical gill anemometer  

Microsoft Academic Search

The paper presents a simple method to compute the stability parameter Z\\/L and boundary-layer parameters such as friction velocity U* and surface heat flux Q0 on an operational basis. The method is based on the autocorrelation function of the vertical velocity which is relatively insensitive to averaging times except for very large lag times. Eddy correlation techniques on the other

P. K. Misra

1979-01-01

447

Transition from natural to mixed convection for steam–gas flow condensing along a vertical plate  

Microsoft Academic Search

An analysis method based on two-phase boundary layer analysis has been developed to study the effects of superimposed forced convection on natural convection steam–gas flow condensing along a vertical plate. The mechanism by which superimposed forced convection enhances heat transfer is evaluated: the bulk flow blows away non-condensable gases accumulating near the interface, resulting in an elevated condensation driving force.

Y. Liao; K. Vierow; A. Dehbi; S. Guentay

2009-01-01

448

Vertical-Velocity Skewness in the Buoyancy-Driven Boundary Layer  

Microsoft Academic Search

A number of puzzling features of the skewness of the vertical velocity field, Sw(z), are found in observations and large-eddy simulations (LES) of the buoyancy-driven planetary boundary layer (PBL). For example, observations of Sw(z) in cases where the air is heated from below indicate that Sw(z) > 0 and remains relatively constant for z 0.3zi, whereas all large-eddy simulations of

Chin-Hoh Moeng; Richard Rotunno

1990-01-01

449

A simple computer program to model three-dimensional underground heat flow with realistic boundary conditions  

SciTech Connect

A FORTRAN computer program called GROCS (Ground Coupled Systems) has been developed to study three-dimensional underground heat flow. Features include the use of up to 30 finite elements or ''blocks'' of earth which interact via finite difference heat flow equations and a subprogram which sets realistic time and depth-dependent boundary conditions. No explicit consideration of moisture movement or freezing is given. GROCS has been used to model the thermal behavior of buried solar heat storage tanks (with and without insulation) and serpentine pipe fields for solar heat pump space conditioning systems. The program is available independently or in a form compatible with specially written TRNSY-S component TYPE subroutines. This paper first describes the approach taken in the design of GROCS, the mathematics contained and the program architecture. Then, the operation of the stand-alone version is explained. Finally, the validity of GROCS is discussed. A companion paper serves as a user's guide to the TRNSY-S compatible subroutine version.

Metz, P.D.

1983-02-01

450

Vertical structures induced by embedded moonlets in Saturn's rings: the gap region  

E-print Network

We study the vertical extent of propeller structures in Saturn's rings. Our focus lies on the gap region of the propeller and on non-inclined propeller moonlets. In order to describe the vertical structure of propellers we extend the model of Spahn and Sremcevic (2000) to include the vertical direction. We find that the gravitational interaction of ring particles with the non-inclined moonlet does not induce considerable vertical excursions of ring particles, but causes a considerable thermal motion in the ring plane. We expect ring particle collisions to partly convert the lateral induced thermal motion into vertical excursions of ring particles. For the gap region of the propeller, we calculate gap averaged propeller heights on the order of 0.7 Hill radii, which is of the order of the moonlet radius. In our model the propeller height decreases exponentially until viscous heating and collisional cooling balance. We estimate Hill radii of 370m and 615m for the propellers Earhart and Bleriot. Our model predict...

Hoffmann, Holger; Seiß, Martin

2012-01-01

451

Vertical InGaN light-emitting diode with a retained patterned sapphire layer.  

PubMed

We present an efficient vertical InGaN light-emitting diode (LED) in which the proposed vertical LEDs were fabricated with patterned sapphire substrates (PSS) using thinning techniques. After the thinning of sapphire substrate, selective dry etching process was performed on the remainder sapphire layer to expose the n-GaN contact layer instead of removing the sapphire substrate using the laser lift-off technique. These processes feature the LEDs with a sapphire-face-up structure and vertical conduction property. The PSS was adopted as a growth substrate to mitigate the light-guided effect, and thereby increase the light-extraction efficiency. Compared with conventional lateral GaN LEDs grown on PSS, the proposed vertical LEDs exhibit a higher light output power and less power degradation at a high driving current. This could be attributed to the fact that the vertical LEDs behave in a manner similar to flip-chip GaN/sapphire LEDs with excellent heat conduction. PMID:23326851

Yang, Y C; Sheu, Jinn-Kong; Lee, Ming-Lun; Yen, C H; Lai, Wei-Chih; Hon, Schang Jing; Ko, Tsun Kai

2012-11-01

452

Vertical InGaN light-emitting diode with a retained patterned sapphire layer.  

PubMed

We present an efficient vertical InGaN light-emitting diode (LED) in which the proposed vertical LEDs were fabricated with patterned sapphire substrates (PSS) using thinning techniques. After the thinning of sapphire substrate, selective dry etching process was performed on the remainder sapphire layer to expose the n-GaN contact layer instead of removing the sapphire substrate using the laser lift-off technique. These processes feature the LEDs with a sapphire-face-up structure and vertical conduction property. The PSS was adopted as a growth substrate to mitigate the light-guided effect, and thereby increase the light-extraction efficiency. Compared with conventional lateral GaN LEDs grown on PSS, the proposed vertical LEDs exhibit a higher light output power and less power degradation at a high driving current. This could be attributed to the fact that the vertical LEDs behave in a manner similar to flip-chip GaN/sapphire LEDs with excellent heat conduction. PMID:23187653

Yang, Y C; Sheu, Jinn-Kong; Lee, Ming-Lun; Yen, C H; Lai, Wei-Chih; Hon, Schang Jing; Ko, Tsun Kai

2012-11-01

453

Non-hydrostatic effect on the thermospheric density and vertical wind: data-model comparisons  

NASA Astrophysics Data System (ADS)

The pressure gradient in the vertical direction is exactly balanced by the gravity force under hydrostatic equilibrium. The simulations from the non-hydrostatic Global Ionosphere Thermosphere Model (GITM) however show that for an idealized case with a sudden intense enhancement of high-latitude Joule heating, the vertical pressure gradient force can locally be 25% larger than the gravity force, resulting in a significant vertical wind (250 m/s) and large neutral density disturbance (100%) at 430 km altitude. Several real case studies have also been conducted to examine the density and wind disturbance related with non-hydrostatic processes. The comparison of Resolute Bay Fabry-Perot Interferometer (FPI) observations with both GITM and the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General-Circulation Model (NCAR-TIEGCM) simulations shows very good consistency of horizontal winds and temperature. On the other hand, GITM predicts strong, rapidly fluctuating vertical motions that the TIEGCM does not. Peak vertical velocities from GITM are of the same order as those from the FPI. The simulated density disturbance will also be compared with observations, such as measurements from CHAMP satellite.

Deng, Y.; Wu, Q.; Richmond, A. D.; Ridley, A.; Roble, R. G.

2008-05-01

454

Vertical distribution of Pahang River plume  

NASA Astrophysics Data System (ADS)

Large rivers transported high amount of discharge towards the sea and induced the river plume formation. The contents of the plume consist of suspended solids, nutrients, pollutants and other particles. Productivity at estuary depends on the organic and nutrient contents from the river discharge. Due to many possible factors, the dispersal of the plume shows spatial variation horizontally and vertically. The monsoonal wind is a factor that effecting plume vertical profile pattern. This study determines the vertical distribution pattern of the plumeat Pahang River through field observation. Several water parameters were measured during cruises conducted at respective monsoon. Data collected includes depth, chlorophyll-a, salinity, temperature and suspended particulate matter. Depth at Pahang's offshore usually does not reached more than 15 m depth because of the shallow continental shelf at South China Sea. The plume has higher concentration at the mouth of the river which causes the area to be less saline and it decreases as the station furthers from the river. Chlorophyll-a is distributed mainly at the surface level where the area is warmer and received freshwater runoff. Suspended particulate matter shows downward distribution from the front of the estuary towards deep water column depth (10 m). Temperature pattern shows warmer surface layer with depth less than 5 m while deeper water column has lower temperature. Vertical profile pattern of Pahang River plume generally shows slight difference between each monsoon by referring to particular parameter.

Taher, T. M.; Lihan, T.; Mustapha, M. A.

2013-11-01

455

A Vertical Approach to Math Instruction  

ERIC Educational Resources Information Center

In the current era of mathematics standards, whether they are Common Core State Standards or other state standards, effective vertical mathematics teams offer an opportunity for teachers to grow professionally through shared experiences, for leadership to grow among the faculty, and for the school to change its perspective on the teaching and…

Gojak, Linda

2012-01-01

456

Vertical & Horizontal GHX's Advantages of Playing Together  

E-print Network

,000. Goldfield Oasis Leisure Centre, Kalgoorlie, WA Kalgoorlie, WA Goldfields Oasis Leisure Centre Perth Sydney Leisure Centre #12;4 Vertical & Horizontal GHX's Advantages of Playing Together IGSHPA Conference competitive pool and large leisure pool. In the last few years cost of electricity has increased

457

Vertical transmission of hepatitis E virus  

Microsoft Academic Search

Little is known about vertical transmission of hepatitis E virus from infected mothers to their infants. We studied eight babies born to mothers infected with hepatitis E in third trimester. One baby was icteric at birth with elevated transaminases and four babies had anicteric hepatitis. Two babies were born with hypothermia and hypoglycaemia and died within 24 h; one had

M. S. Khuroo; S. Kamali; S. Jameel

1995-01-01

458

Early surgical treatment for congenital vertical talus  

Microsoft Academic Search

Congenital vertical talus is characterised by a dislocated talonavicular joint in association with an equinus position of the calcaneus. We report the results in 13 operated feet in 10 children, 3 of whom (5 feet) presented with a primary neurological disorder and 2 of whom (3 feet) suffered from arthrogryposis multiplex congenita. The other children were normal. All patients were

T. Wirth; P. Schuler; P. Griss

1994-01-01

459

Brand Equity and Vertical Product Line Extent  

Microsoft Academic Search

This paper addresses the question of how the vertical structure of a product line relates to brand equity. Does the presence of “premium” or high-quality products in a product line enhance brand equity? Conversely, does the presence of “economy” or low-quality products in a product line diminish brand equity? Economists and marketing researchers refer to variation in quality levels of

Taylor Randall; Karl Ulrich; David Reibstein

1998-01-01

460

Vertically aligned biaxially textured molybdenum thin films  

NASA Astrophysics Data System (ADS)

Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85° 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° 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.

Krishnan, Rahul; Riley, Michael; Lee, Sabrina; Lu, Toh-Ming

2011-09-01