Influence of mobile air-conditioning on vehicle emissions and fuel consumption: a model approach for modern gasoline cars used in Europe.

PubMed

Weilenmann, Martin F; Vasic, Ana-Marija; Stettler, Peter; Novak, Philippe

2005-12-15

The influence of air-conditioning activity on the emissions and fuel consumption of passenger cars is an important issue, since fleet penetration and use of these systems have reached a high level. Apart from the MOBILE6 study in the United States, little data is available on the impact of air-conditioning devices (A/Cs). Since weather conditions and A/C technologies both differ from those in the U. S., a test series was designed for the European setting. A fleet of six modern gasoline passenger cars was tested in different weather conditions. Separate test series were carried out for the initial cooldown and for the stationary situation of keeping the interior of the vehicle cool. As assumed, CO2 emissions and fuel consumption rise with the thermal load. This also causes a notable rise in CO and hydrocarbons (HCs). Moreover, A/Cs do not stop automatically at low ambient temperatures; if necessary, they produce dry air to demist the windscreen. A model is proposed that shows a constant load for lower temperatures and a linear trend for higher temperatures. The initial cooldown tests highlight significant differences among cars but show that A/C operation for the initial cooling of an overheated passenger compartment does not result in any extra emissions for the fleet as a whole.

Dielectrophoretic particle-particle interaction under AC electrohydrodynamic flow conditions.

PubMed

Lee, Doh-Hyoung; Yu, Chengjie; Papazoglou, Elisabeth; Farouk, Bakhtier; Noh, Hongseok M

2011-09-01

We used the Maxwell stress tensor method to understand dielectrophoretic particle-particle interactions and applied the results to the interpretation of particle behaviors under alternating current (AC) electrohydrodynamic conditions such as AC electroosmosis (ACEO) and electrothermal flow (ETF). Distinct particle behaviors were observed under ACEO and ETF. Diverse particle-particle interactions observed in experiments such as particle clustering, particles keeping a certain distance from each other, chain and disc formation and their rotation, are explained based on the numerical simulation data. The improved understanding of particle behaviors in AC electrohydrodynamic flows presented here will enable researchers to design better particle manipulation strategies for lab-on-a-chip applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of biological aerosol exposure risks from automobile air conditioning system.

PubMed

Li, Jing; Li, Mingzhen; Shen, Fangxia; Zou, Zhuanglei; Yao, Maosheng; Wu, Chang-yu

2013-09-17

Although use of automobile air conditioning (AC) was shown to reduce in-vehicle particle levels, the characterization of its microbial aerosol exposure risks is lacking. Here, both AC and engine filter dust samples were collected from 30 automobiles in four different geographical locations in China. Biological contents (bacteria, fungi, and endotoxin) were studied using culturing, high-throughput gene sequence, and Limulus amebocyte lysate (LAL) methods. In-vehicle viable bioaerosol concentrations were directly monitored using an ultraviolet aerodynamic particle sizer (UVAPS) before and after use of AC for 5, 10, and 15 min. Regardless of locations, the vehicle AC filter dusts were found to be laden with high levels of bacteria (up to 26,150 CFU/mg), fungi (up to 1287 CFU/mg), and endotoxin (up to 5527 EU/mg). More than 400 unique bacterial species, including human opportunistic pathogens, were detected in the filter dusts. In addition, allergenic fungal species were also found abundant. Surprisingly, unexpected fluorescent peaks around 2.5 μm were observed during the first 5 min use of AC, which was attributed to the reaerosolization of those filter-borne microbial agents. The information obtained here can assist in minimizing or preventing the respiratory allergy or infection risk from the use of automobile AC system.

Interaction of temperature, humidity, driver preferences, and refrigerant type on air conditioning compressor usage.

PubMed

Levine, C; Younglove, T; Barth, M

2000-10-01

Recent studies have shown large increases in vehicle emissions when the air conditioner (AC) compressor is engaged. Factors that affect the compressor-on percentage can have a significant impact on vehicle emissions and can also lead to prediction errors in current emissions models if not accounted for properly. During 1996 and 1997, the University of California, Riverside, College of Engineering-Center for Environmental Research and Technology (CE-CERT) conducted a vehicle activity study for the California Air Resources Board (CARB) in the Sacramento, CA, region. The vehicles were randomly selected from all registered vehicles in the region. As part of this study, ten vehicles were instrumented to collect AC compressor on/off data on a second-by-second basis in the summer of 1997. Temperature and humidity data were obtained and averaged on an hourly basis. The ten drivers were asked to complete a short survey about AC operational preferences. This paper examines the effects of temperature, humidity, refrigerant type, and driver preferences on air conditioning compressor activity. Overall, AC was in use in 69.1% of the trips monitored. The compressor was on an average of 64% of the time during the trips. The personal preference settings had a significant effect on the AC compressor-on percentage but did not interact with temperature. The refrigerant types, however, exhibited a differential response across temperature, which may necessitate separate modeling of the R12 refrigerant-equipped vehicles from the R134A-equipped vehicles. It should be noted that some older vehicles do get retrofitted with new compressors that use R134A; however, none of the vehicles in this study had been retrofitted.

In-car particles and cardiovascular health: an air conditioning-based intervention study.

PubMed

Chuang, Hsiao-Chi; Lin, Lian-Yu; Hsu, Ya-Wen; Ma, Chih-Ming; Chuang, Kai-Jen

2013-05-01

Exposure to traffic-related particulate matter (PM) is considered a potential risk for cardiovascular events. Little is known about whether improving air quality in car can modify cardiovascular effects among human subjects during commuting. We recruited a panel of 60 healthy subjects to commute for 2 h by a car equipped with an air conditioning (AC) system during the morning rush hour in Taipei. Operation modes of AC system using outside air (OA-mode), circulating inside air (IA-mode) and turning off (Off-mode) were examined. Repeated measurements of heart rate variability (HRV) indices, PM≤2.5 μm in aerodynamic diameter (PM2.5) and noise level were conducted for each participant in different modes during the commute. We used linear mixed-effects models to associate HRV indices with in-car PM2.5. We found that decreases in HRV indices were associated with increased levels of in-car PM2.5. For Off-mode, an interquartile range (IQR) increase in in-car PM2.5 with 15-min moving average was associated with 2.7% and 4.1% decreases in standard deviation of NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), respectively. During OA and IA modes, participants showed slight decreases in SDNN (OA mode: 0.1%; IA mode: 1.3%) and r-MSSD (OA mode: 1.1%; IA mode: 1.8%) by an IQR increase in in-car PM2.5 with 15-min moving average. We concluded that in-car PM2.5 is associated with autonomic alteration. Utilization of the car's AC system can improve air quality and modify the effects of in-car PM2.5 on HRV indices among human subjects during the commute. Copyright © 2013 Elsevier B.V. All rights reserved.

Air Conditioning in Nearly 100 Million U.S. Homes

EIA Publications

2011-01-01

Except in the temperate climate regions along the West Coast, air conditioners (AC) are now standard equipment in most U.S. homes. As recently as 1993, only 68% of all occupied housing units had AC. The latest results from the 2009 Residential Energy Consumption Survey (RECS) show that 87% of U.S. households are now equipped with AC. This growth occurred among all housing types and in every Census region. Wider use has coincided with much improved energy efficiency standards for AC equipment, a population shift to hotter and more humid regions, and a housing boom during which average housing sizes increased.

REACH. Air Conditioning Units.

ERIC Educational Resources Information Center

Garrison, Joe; And Others

As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of air conditioning. The instructional units focus on air conditioning fundamentals, window air conditioning, system and installation, troubleshooting and…

Impact of ventilation scenario on air exchange rates and on indoor particle number concentrations in an air-conditioned classroom

NASA Astrophysics Data System (ADS)

Guo, H.; Morawska, L.; He, C.; Gilbert, D.

A 2-week intensive measurement campaign of indoor and outdoor air pollution was carried out in September 2006, in a primary school to investigate indoor-outdoor correlations of particle number (PN) concentrations, and the impact of air exchange rate (ACH) on the indoor PN concentration. The ACHs in the classroom for different conditions associated with window opening and the operational status of air conditioners (A/C) and fans were tested. As expected, the lowest ACH (0.12 h -1) was found when the windows were closed and A/C and fans were off. In contrast, the highest ACH (7.92 h -1) was observed when the windows were opened and A/C and fans were all on. The analysis of the PN I/ O ratios at different ACHs in the absence of indoor sources indicates that the mean I/ O ratio was 0.621±0.007 (mean±95% confidence interval) when the windows were closed, and A/C and fans were off; 0.524±0.023 when windows were closed, fans were off and A/C was on; and 0.502±0.029 when windows were closed, A/C was off and fans were on. To further understand the relationship between indoor and outdoor PN concentrations, the impact of outdoor PN concentration on I/ O ratios at different ACHs was investigated. It was found that the relationship between outdoor PN concentration and the I/ O ratio at different ACHs followed a power trendline with an equation of I/ O ratio= A PN out-b ( A and b are coefficients, PN out is outdoor PN concentration), suggesting that the penetration efficiency decreased with increasing outdoor PN concentration. It is the first time we found that when the outdoor PN concentration increased there was an associated increase in the concentration of nano-particles, which have been demonstrated to have higher deposition rates and lower penetration efficiencies. Based on the above equation, the study also showed a significant effect of ACH on indoor PN concentrations under stable outdoor PN concentrations. In general, the higher the ACH was, the lower the indoor PN

Evaluation Framework and Analyses for Thermal Energy Storage Integrated with Packaged Air Conditioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, F.; Deru, M.; Bonnema, E.

2013-10-01

Few third-party guidance documents or tools are available for evaluating thermal energy storage (TES) integrated with packaged air conditioning (AC), as this type of TES is relatively new compared to TES integrated with chillers or hot water systems. To address this gap, researchers at the National Renewable Energy Laboratory conducted a project to improve the ability of potential technology adopters to evaluate TES technologies. Major project outcomes included: development of an evaluation framework to describe key metrics, methodologies, and issues to consider when assessing the performance of TES systems integrated with packaged AC; application of multiple concepts from the evaluationmore » framework to analyze performance data from four demonstration sites; and production of a new simulation capability that enables modeling of TES integrated with packaged AC in EnergyPlus. This report includes the evaluation framework and analysis results from the project.« less

The performance of a mobile air conditioning system with a water cooled condenser

NASA Astrophysics Data System (ADS)

Di Battista, Davide; Cipollone, Roberto

2015-11-01

Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

Remote Supervision and Control of Air Conditioning Systems in Different Modes

NASA Astrophysics Data System (ADS)

Rafeeq, Mohammed; Afzal, Asif; Rajendra, Sree

2018-01-01

In the era of automation, most of the application of engineering and science are interrelated with system for optimal operation. To get the efficient result of an operation and desired response, interconnected systems should be controlled by directing, regulating and commanding. Here, air conditioning (AC) system is considered for experimentation, to supervise and control its functioning in both, automated and manual mode. This paper reports the work intended to design and develop an automated and manual AC system working in remote and local mode, to increase the level of comfort, easy operation, reducing human intervention and faults occurring in the system. The Programmable Logical Controller (PLC) and Supervisory Control and Data Acquisition (SCADA) system were used for remote supervision and monitoring of AC systems using series ninety protocol and remote terminal unit modbus protocol as communication module to operate in remote mode. PLC was used as remote terminal for continuous supervision and control of AC system. SCADA software was used as a tool for designing user friendly graphical user interface. The proposed SCADA AC system successfully monitors and controls in accordance within the parameter limits like temperature, pressure, humidity and voltage. With all the features, this designed system is capable of efficient handling of the resources like the compressor, humidifier etc., with all the levels of safety and durability. This system also maintains the temperature and controls the humidity of the remote location and also looks after the health of the compressor.

Needle-array to Plate DBD Plasma Using Sine AC and Nanosecond Pulse Excitations for Purpose of Improving Indoor Air Quality

PubMed Central

Zhang, Li; Yang, Dezheng; Wang, Wenchun; Wang, Sen; Yuan, Hao; Zhao, Zilu; Sang, Chaofeng; Jia, Li

2016-01-01

In this study, needle-array to plate electrode configuration was employed to generate an atmospheric air diffuse discharge using both nanosecond pulse and sine AC voltage as excitation voltage for the purpose of improving indoor air quality. Different types of voltage sources and electrode configurations are employed to optimize electrical field distribution and improve discharge stability. Discharge images, electrical characteristics, optical emission spectra, and plasma gas temperatures in both sine AC discharge and nanosecond pulse discharge were compared and the discharge stability during long operating time were discussed. Compared with the discharge excited by sine AC voltage, the nanosecond pulsed discharge is more homogenous and stable, besides, the plasma gas temperature of nanosecond pulse discharge is much lower. Using packed-bed structure, where γ- Al2O3 pellets are filled in the electrode gap, has obvious efficacy in the production of homogenous discharge. Furthermore, both sine AC discharge and nanosecond pulse discharge were used for removing formaldehyde from flowing air. It shows that nanosecond pulse discharge has a significant advantage in energy cost. And the main physiochemical processes for the generation of active species and the degradation of formaldehyde were discussed. PMID:27125663

The study of operating an air conditioning system using Maisotsenko-Cycle

NASA Astrophysics Data System (ADS)

Khan, Mohammad S.; Tahan, Sami; Toufic El-Achkar, Mohamad; Abou Jamus, Saleh

2018-03-01

The project aims to design and build an air conditioning system that runs on the Maisotsenko cycle. The system is required to condition and cool down ambient air for a small residential space with the reduction in the use of electricity and eliminating the use of commercial refrigerants. This project can operate at its optimum performance in remote areas like oil diggers and other projects that run in the desert or any site that would not have a very high relative humidity level. The Maisotsenko cycle is known as the thermodynamic concept that captures energy from the air by using the psychometric renewable energy available in the latent heat in water evaporating in air. The heat and mass exchanger design was based on choosing a material that would-be water resistant and breathable, which was found to be layers of cardboard placed on top of each other and thus creating channels for air to pass through. Aiming for this design eliminates any high power electrical equipment such as compressors, condensers and evaporators that would be used in an AC system with the exception of a 600 W blower and a 10 W fan, thus making it a more environmentally friendly project. Moreover, the project is limited by the ambient temperature and humidity, as the model operates at an optimum when the relative humidity is lower.

Superconducting shielded core reactor with reduced AC losses

DOEpatents

Cha, Yung S.; Hull, John R.

2006-04-04

A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

Comparative study of air-conditioning energy use of four office buildings in China and USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xin; Yan, Da; An, Jingjing

Energy use in buildings has great variability. In order to design and operate low energy buildings as well as to establish building energy codes and standards and effective energy policy, it is crucial to understand and quantify key factors influencing building energy performance. Here, this study investigates air-conditioning (AC) energy use of four office buildings in four locations: Beijing, Taiwan, Hong Kong, and Berkeley. Building simulation was employed to quantify the influences of key factors, including climate, building envelope and occupant behavior. Through simulation of various combinations of the three influencing elements, it is found that climate can lead tomore » AC cooling consumption differences by almost two times, while occupant behavior resulted in the greatest differences (of up to three times) in AC cooling consumption. The influence of occupant behavior on AC energy consumption is not homogeneous. Under similar climates, when the occupant behavior in the building differed, the optimized building envelope design also differed. In conclusion, the optimal building envelope should be determined according to the climate as well as the occupants who use the building.« less

Comparative study of air-conditioning energy use of four office buildings in China and USA

DOE PAGES

Zhou, Xin; Yan, Da; An, Jingjing; ...

2018-04-05

Energy use in buildings has great variability. In order to design and operate low energy buildings as well as to establish building energy codes and standards and effective energy policy, it is crucial to understand and quantify key factors influencing building energy performance. Here, this study investigates air-conditioning (AC) energy use of four office buildings in four locations: Beijing, Taiwan, Hong Kong, and Berkeley. Building simulation was employed to quantify the influences of key factors, including climate, building envelope and occupant behavior. Through simulation of various combinations of the three influencing elements, it is found that climate can lead tomore » AC cooling consumption differences by almost two times, while occupant behavior resulted in the greatest differences (of up to three times) in AC cooling consumption. The influence of occupant behavior on AC energy consumption is not homogeneous. Under similar climates, when the occupant behavior in the building differed, the optimized building envelope design also differed. In conclusion, the optimal building envelope should be determined according to the climate as well as the occupants who use the building.« less

The Future of Air Conditioning for Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goetzler, William; Guernsey, Matt; Young, Jim

BTO works with researchers and industry to develop and deploy technologies that can substantially reduce energy consumption and greenhouse gas (GHG) emissions in residential and commercial buildings. Air conditioning systems in buildings contribute to GHG emissions both directly through refrigerant emissions, as well as indirectly through fossil fuel combustion for power generation. BTO promotes pre-competitive research and development on next-generation HVAC technologies that support the phase down of hydrofluorocarbon (HFC) production and consumption, as well as cost-effective energy efficiency improvements. DOE provides, with this report, a fact-based vision for the future of A/C use around the world. DOE intends formore » this vision to reflect a broad and balanced aggregation of perspectives. DOE brings together this content in an effort to support dialogue within the international community and help keep key facts and objectives at the forefront among the many important discussions.« less

Challenges of using air conditioning in an increasingly hot climate

NASA Astrophysics Data System (ADS)

Lundgren-Kownacki, Karin; Hornyanszky, Elisabeth Dalholm; Chu, Tuan Anh; Olsson, Johanna Alkan; Becker, Per

2018-03-01

At present, air conditioning (AC) is the most effective means for the cooling of indoor space. However, its increased global use is problematic for various reasons. This paper explores the challenges linked to increased AC use and discusses more sustainable alternatives. A literature review was conducted applying a transdisciplinary approach. It was further complemented by examples from cities in hot climates. To analyse the findings, an analytical framework was developed which considers four societal levels—individual, community, city, and national. The main challenges identified from the literature review are as follows: environmental, organisational, socio-economical, biophysical and behavioural. The paper also identifies several measures that could be taken to reduce the fast growth of AC use. However, due to the complex nature of the problem, there is no single solution to provide sustainable cooling. Alternative solutions were categorised in three broad categories: climate-sensitive urban planning and building design, alternative cooling technologies, and climate-sensitive attitudes and behaviour. The main findings concern the problems arising from leaving the responsibility to come up with cooling solutions entirely to the individual, and how different societal levels can work towards more sustainable cooling options. It is concluded that there is a need for a more holistic view both when it comes to combining various solutions as well as involving various levels in society.

Indoor air quality in Brazilian universities.

PubMed

Jurado, Sonia R; Bankoff, Antônia D P; Sanchez, Andrea

2014-07-11

This study evaluated the indoor air quality in Brazilian universities by comparing thirty air-conditioned (AC) (n = 15) and naturally ventilated (NV) (n = 15) classrooms. The parameters of interest were indoor carbon dioxide (CO2), temperature, relative humidity (RH), wind speed, viable mold, and airborne dust levels. The NV rooms had larger concentration of mold than the AC rooms (1001.30 ± 125.16 and 367.00 ± 88.13 cfu/m3, respectively). The average indoor airborne dust concentration exceeded the Brazilian standards (<80 µg/m3) in both NV and AC classrooms. The levels of CO2 in the AC rooms were significantly different from the NV rooms (1433.62 ± 252.80 and 520.12 ± 37.25 ppm, respectively). The indoor air quality in Brazilian university classrooms affects the health of students. Therefore, indoor air pollution needs to be considered as an important public health problem.

The Future of Air Conditioning for Buildings - Executive Summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goetzler, William; Guernsey, Matt; Young, J.

2016-07-01

The Building Technologies Office (BTO), within the U.S. Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy, works with researchers and industry to develop and deploy technologies that can substantially reduce energy consumption and greenhouse gas (GHG) emissions in residential and commercial buildings. Air conditioning (A/C) systems in buildings contribute to GHG emissions both directly through refrigerant emissions, as well as indirectly through fossil fuel combustion for power generation. BTO promotes pre-competitive research and development (R&D) on next-generation HVAC technologies that support the phase down of hydrofluorocarbon (HFC) production and consumption, as well as cost-effective energy efficiency improvements.more » Over the past several decades, product costs and lifecycle cooling costs have declined substantially in many global markets due to improved, higher-volume manufacturing and higher energy efficiency driven by R&D investments and efficiency policies including minimum efficiency standards and labeling programs.1 This report characterizes the current landscape and trends in the global A/C market, including discussion of both direct and indirect climate impacts, and potential global warming impacts from growing global A/C usage. The report also documents solutions that can help achieve international goals for energy efficiency and GHG emissions reductions. The solutions include pathways related to low-global warming potential2 (GWP) refrigerants, energy efficiency innovations, long-term R&D initiatives, and regulatory actions. DOE provides, with this report, a fact-based vision for the future of A/C use around the world. DOE intends for this vision to reflect a broad and balanced aggregation of perspectives. DOE brings together this content in an effort to support dialogue within the international community and help keep key facts and objectives at the forefront among the many important discussions.« less

Indoor Air Quality in Brazilian Universities

PubMed Central

Jurado, Sonia R.; Bankoff, Antônia D. P.; Sanchez, Andrea

2014-01-01

This study evaluated the indoor air quality in Brazilian universities by comparing thirty air-conditioned (AC) (n = 15) and naturally ventilated (NV) (n = 15) classrooms. The parameters of interest were indoor carbon dioxide (CO2), temperature, relative humidity (RH), wind speed, viable mold, and airborne dust levels. The NV rooms had larger concentration of mold than the AC rooms (1001.30 ± 125.16 and 367.00 ± 88.13 cfu/m3, respectively). The average indoor airborne dust concentration exceeded the Brazilian standards (<80 μg/m3) in both NV and AC classrooms. The levels of CO2 in the AC rooms were significantly different from the NV rooms (1433.62 ± 252.80 and 520.12 ± 37.25 ppm, respectively). The indoor air quality in Brazilian university classrooms affects the health of students. Therefore, indoor air pollution needs to be considered as an important public health problem. PMID:25019268

No-reheat air-conditioning

NASA Technical Reports Server (NTRS)

Obler, H. D.

1980-01-01

Air conditioning system, for environmentally controlled areas containing sensitive equipment, regulates temperature and humidity without wasteful and costly reheating. System blends outside air with return air as dictated by various sensors to ensure required humidity in cooled spaces (such as computer room).

Relationship between Air Pollution and Weather Conditions under Complicated Geographical conditions

NASA Astrophysics Data System (ADS)

Cheng, Q.; Jiang, P.; Li, M.

2017-12-01

Air pollution is one of the most serious issues all over the world, especially in megacities with constrained geographical conditions for air pollution diffusion. However, the dynamic mechanism of air pollution diffusion under complicated geographical conditions is still be confused. Researches to explore relationship between air pollution and weather conditions from the perspective of local atmospheric circulations can contribute more to solve such problem. We selected three megacities (Beijing, Shanghai and Guangzhou) under different geographical condition (mountain-plain transition region, coastal alluvial plain and coastal hilly terrain) to explore the relationship between air pollution and weather conditions. RDA (Redundancy analysis) model was used to analyze how the local atmospheric circulation acts on the air pollutant diffusion. The results show that there was a positive correlation between the concentration of air pollutants and air pressure, while temperature, precipitation and wind speed have negative correlations with the concentration of air pollutants. Furthermore, geographical conditions, such as topographic relief, have significant effects on the direction, path and intensity of local atmospheric circulation. As a consequence, air pollutants diffusion modes in different cities under various geographical conditions are diverse from each other.

40 CFR 1066.845 - AC17 air conditioning efficiency test procedure.

Code of Federal Regulations, 2014 CFR

2014-07-01

... solar heating is disabled for certain test intervals as described in this section. (d) Interior air... vehicle's windows and operate the vehicle over a preconditioning UDDS with no solar heating and with the... cooling fans. (3) Turn on solar heating within one minute after turning off the engine. Once the solar...

[Microbial air purity in hospitals. Operating theatres with air conditioning system].

PubMed

Krogulski, Adam; Szczotko, Maciej

2010-01-01

The aim of this study was to show the influence of air conditioning control for microbial contamination of air inside the operating theatres equipped with correctly working air-conditioning system. This work was based on the results of bacteria and fungi concentration in hospital air obtained since 2001. Assays of microbial air purity conducted on atmospheric air in parallel with indoor air demonstrated that air filters applied in air-conditioning systems worked correctly in every case. To show the problem of fluctuation of bacteria concentration more precisely, every sequences of single results from successive measure series were examined independently.

Measurement of activated species generated by AC power excited non-equilibrium atmospheric pressure Ar plasma jet with air engulfment

NASA Astrophysics Data System (ADS)

Takeda, Keigo; Ishikawa, Kenji; Tanaka, Hiromasa; Kano, Hiroyuki; Sekine, Makoto; Hori, Masaru

2013-09-01

Non-equilibrium atmospheric pressure plasma jet (NEAPPJ) is very attractive tool for bio and medical applications. In the plasma treatments, samples are typically located at a far region from main discharge, and treated in open air without purge gases. Influence of air engulfment on generation of activated species in the NEAPPJ in open air is a large issue for the application. In this study, the AC excited argon NEAPPJ with the gas flow rate of 2 slm was generated under the open air condition. The densities of the grand state nitrogen monoxide (NO) and the ground state O atom generated by the NEAPPJ were measured by laser induced fluorescence spectroscopy and vacuum ultraviolet absorption spectroscopy. The length of the plasma jet was around 10 mm. Up to 10 mm, the NO density increased with increasing the distance from plasma head, and then saturated in remote region of plasma. On the other hand, the O atom density decreased from 1014 to 1013 cm-3 with increasing the distance. Especially, the amount of decrease in O atom density became the largest at the plasma edge. We will discuss the generation and loss processes of activated species generated in the NEAPPJ with the measurement results using spectroscopic methods.

Natural convection liquid desiccant loop as an auxiliary air conditioning system: investigating the operational parameters

NASA Astrophysics Data System (ADS)

Fazilati, Mohammad Ali; Alemrajabi, Ali Akbar; Sedaghat, Ahmad

2018-03-01

Liquid desiccant air conditioning system with natural convection was presented previously as a new generation of AC systems. The system consists of two three-fluid energy exchangers namely absorber and regenerator in which the action of air dehumidifying and desiccant regeneration is done, respectively. The influence of working parameters on system performance including the heat source and heat sink temperature, concentration of desiccant solution fills the system initially and humidity content of inlet air to regenerator is investigated experimentally. The heat source temperatures of 50 °C and 60 °C, heat sink temperatures of 15 °C and 20 °C and desiccant concentrations of 30% and 34%, are examined here. The inlet air to regenerator has temperature of 38.5 °C and three relative humidity of 14%, 38% and 44%. In all experiments, the inlet air to absorber has temperature of 31 °C and relative humidity of 75%. By inspecting evaluation indexes of system, it is revealed that higher startup desiccant concentration solution is more beneficial for all study cases. It is also observed although the highest/lowest temperature heat source/heat sink is most suitable for best system operation, increasing the heat source temperature should be accompanied with decreasing heat sink temperature. Using drier air stream for regenerator inlet does not necessarily improve system performance; and the air stream with proper value of humidity content should be employed. Finally after running the system in its best working condition, the coefficient of performance (COP) reached 4.66 which verified to be higher than when the same air conditioning task done by a conventional vapor compression system, in which case the COP was 3.38.

Dynamic characteristics of corona discharge generated under rainfall condition on AC charged conductors

NASA Astrophysics Data System (ADS)

Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

2017-12-01

By synchronous measurement of corona current and the water droplet deformation process on a conductor surface, different types of corona discharge are visualized when AC voltage is applied on a line-ground electrode system. The corona characteristics are closely related to the applied voltage and water supply rate. With the increase of AC voltage, the positive Taylor cone discharge firstly appears and then disappears, replaced by the dripping and crashing discharge. Furthermore, the number of pulses in each pulse train increases with the increase of applied voltage. The mechanism of the transfer from the positive Taylor cone discharge to the dripping and crashing discharge is found to be related to the oscillation process of the water droplet. The water supply rate also has a great influence on the characteristics of corona currents. The number of positive pulse trains increases linearly when the water supply rate gets larger, leading to a higher audible noise and radio interference level from the AC corona, which is quite different from that of the DC corona. The difference between the AC and DC coronas under rainfall conditions is analyzed finally.

Fuel consumption and CO2/pollutant emissions of mobile air conditioning at fleet level - new data and model comparison.

PubMed

Weilenmann, Martin F; Alvarez, Robert; Keller, Mario

2010-07-01

Mobile air conditioning (MAC) systems are the second-largest energy consumers in cars after driving itself. While different measurement series are available to illustrate their behavior in hot ambient conditions, little data are available for lower temperatures. There are also no data available on diesel vehicles, despite these being quite common in Europe (up to 70% of the fleet in some countries). In the present study, six representative modern diesel passenger cars were tested. In combination with data from previous measurements on gasoline cars, a new model was developed - EEMAC = Empa Emission model for Mobile Air Conditioning systems - to predict emissions from air conditioning. The measurements obtained show that A/C activity still occurs at temperatures below the desired interior temperature. The EEMAC model was applied to the average meteorological year of a central European region and compared with the US EPA MOBILE6 model. As temperatures in central Europe are often below 20 degrees C (the point below which the two models differ), the overall results differ clearly. The estimated average annual CO(2) output according to EEMAC is six times higher than that of MOBILE6. EEMAC also indicates that around two-thirds of the fuel used for air conditioning could be saved by switching the MAC system off below 18 degrees C.

Seminar 14 - Desiccant Enhanced Air Conditioning: Desiccant Enhanced Evaporative Air Conditioning (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozubal, E.

2013-02-01

This presentation explains how liquid desiccant based coupled with an indirect evaporative cooler can efficiently produce cool, dry air, and how a liquid desiccant membrane air conditioner can efficiently provide cooling and dehumidification without the carryover problems of previous generations of liquid desiccant systems. It provides an overview to a liquid desiccant DX air conditioner that can efficiently provide cooling and dehumidification to high latent loads without the need for reheat, explains how liquid desiccant cooling and dehumidification systems can outperform vapor compression based air conditioning systems in hot and humid climates, explains how liquid desiccant cooling and dehumidification systemsmore » work, and describes a refrigerant free liquid desiccant based cooling system.« less

Retrofitting Air Conditioning and Duct Systems in Hot, Dry Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shapiro, C.; Aldrich, R.; Arena, L.

2012-07-01

This technical report describes CARB's work with Clark County Community Resources Division in Las Vegas, Nevada, to optimize procedures for upgrading cooling systems on existing homes in the area to implement health, safety, and energy improvements. Detailed monitoring of five AC systems showed that three of the five systems met or exceeded air flow rate goals.

The optimum intermediate pressure of two-stages vapor compression refrigeration cycle for Air-Conditioning unit

NASA Astrophysics Data System (ADS)

Ambarita, H.; Sihombing, H. V.

2018-03-01

Vapor compression cycle is mainly employed as a refrigeration cycle in the Air-Conditioning (AC) unit. In order to save energy, the Coefficient of Performance (COP) of the need to be improved. One of the potential solutions is to modify the system into multi-stages vapor compression cycle. The suitable intermediate pressure between the high and low pressures is one of the design issues. The present work deals with the investigation of an optimum intermediate pressure of two-stages vapor compression refrigeration cycle. Typical vapor compression cycle that is used in AC unit is taken into consideration. The used refrigerants are R134a. The governing equations have been developed for the systems. An inhouse program has been developed to solve the problem. COP, mass flow rate of the refrigerant and compressor power as a function of intermediate pressure are plotted. It was shown that there exists an optimum intermediate pressure for maximum COP. For refrigerant R134a, the proposed correlations need to be revised.

Air Conditioner Charging. Automotive Mechanics. Air Conditioning. Instructor's Guide [and] Student Guide.

ERIC Educational Resources Information Center

Spignesi, B.

This instructional package, one in a series of individualized instructional units on automobile air conditioning, consists of a student guide and an instructor guide dealing with air conditioning charging. Covered in the module are checking the air conditioning system for leaks, checking and adding refrigerant oil as needed, evacuating the system,…

Verify Module for Reporting A/C and Off-Cycle GHG Credits for Light-Duty Vehicle and Truck Manufacturers

EPA Pesticide Factsheets

This EPA presentation provides information on using the new Verify module, streamlining the process required to electronically submit annual reporting of air conditioning (A/C) and off-cycle GHG credits for light duty manufacturers.

ALTERNATIVE TECHNOLOGIES FOR REFRIGERATION AND AIR-CONDITIONING APPLICATIONS

EPA Science Inventory

The report gives results of an assessment of refrigeration technologies that are alternatives to vapor compression refrigeration for use in five application categories: domestic air conditioning, commercial air conditioning, mobile air conditioning, domestic refrigeration, and co...

A hybrid air conditioner driven by a hybrid solar collector

NASA Astrophysics Data System (ADS)

Al-Alili, Ali

The objective of this thesis is to search for an efficient way of utilizing solar energy in air conditioning applications. The current solar Air Conditioners (A/C)s suffer from low Coefficient of Performance (COP) and performance degradation in hot and humid climates. By investigating the possible ways of utilizing solar energy in air conditioning applications, the bottlenecks in these approaches were identified. That resulted in proposing a novel system whose subsystem synergy led to a COP higher than unity. The proposed system was found to maintain indoor comfort at a higher COP compared to the most common solar A/Cs, especially under very hot and humid climate conditions. The novelty of the proposed A/C is to use a concentrating photovoltaic/thermal collector, which outputs thermal and electrical energy simultaneously, to drive a hybrid A/C. The performance of the hybrid A/C, which consists of a desiccant wheel, an enthalpy wheel, and a vapor compression cycle (VCC), was investigated experimentally. This work also explored the use of a new type of desiccant material, which can be regenerated with a low temperature heat source. The experimental results showed that the hybrid A/C is more effective than the standalone VCC in maintaining the indoor conditions within the comfort zone. Using the experimental data, the COP of the hybrid A/C driven by a hybrid solar collector was found to be at least double that of the current solar A/Cs. The innovative integration of its subsystems allows each subsystem to do what it can do best. That leads to lower energy consumption which helps reduce the peak electrical loads on electric utilities and reduces the consumer operating cost since less energy is purchased during the on peak periods and less solar collector area is needed. In order for the proposed A/C to become a real alternative to conventional systems, its performance and total cost were optimized using the experimentally validated model. The results showed that for an

The Effect of Computers on School Air-Conditioning.

ERIC Educational Resources Information Center

Fickes, Michael

2000-01-01

Discusses the issue of increased air-conditioning demand when schools equip their classrooms with computers that require enhanced and costlier air-conditioning systems. Air-conditioning costs are analyzed in two elementary schools and a middle school. (GR)

Life Cycle Impact Assessment of a Rainwater Harvesting System Compared with an A/C Condensate System

EPA Science Inventory

This study reviewed U.S. commercial buildings to design a decentralized rooftop rainwater harvesting (RWH) system and air-conditioning (AC) condensate harvesting (ACH) system for non-potable use. RWH systems were designed for one-to multi-story buildings selected from each of th...

Air Conditioning. Performance Objectives. Intermediate Course.

ERIC Educational Resources Information Center

Long, William

Several intermediate performance objectives and corresponding criterion measures are listed for each of seven terminal objectives for an intermediate air conditioning course. The titles of the seven terminal objectives are Refrigeration Cycle, Job Requirement Skills, Air Conditioning, Trouble Shooting, Performance Test, Shop Management, and S.I.E.…

Air Conditioning and Heating Technology--II.

ERIC Educational Resources Information Center

Gattone, Felix

Twenty-eight chapters and numerous drawings provide information for instructors and students of air conditioning and heating technology. Chapter 1 lists the occupational opportunities in the field. Chapter 2 covers the background or development of the industry of air conditioning and heating technology. Chapter 3 includes some of the principle…

Concentrated Solar Air Conditioning for Buildings Project

NASA Technical Reports Server (NTRS)

McLaughlin, Rusty

2010-01-01

This slide presentation reviews project to implement the use of solar power to provide air conditioning for NASA buildings. Included is an overall conceptual schematic, and an diagram of the plumbing and instrumentation for the project. The use of solar power to power air conditioning in buildings, particularly in the Southwest, could save a significant amount of money. DOD studies have concluded that air conditioning accounts for 30-60% of total energy expenditures.

The air-conditioning capacity of the human nose.

PubMed

Naftali, Sara; Rosenfeld, Moshe; Wolf, Michael; Elad, David

2005-04-01

The nose is the front line defender of the respiratory system. Unsteady simulations in three-dimensional models have been developed to study transport patterns in the human nose and its overall air-conditioning capacity. The results suggested that the healthy nose can efficiently provide about 90% of the heat and the water fluxes required to condition the ambient inspired air to near alveolar conditions in a variety of environmental conditions and independent of variations in internal structural components. The anatomical replica of the human nose showed the best performance and was able to provide 92% of the heating and 96% of the moisture needed to condition the inspired air to alveolar conditions. A detailed analysis explored the relative contribution of endonasal structural components to the air-conditioning process. During a moderate breathing effort, about 11% reduction in the efficacy of nasal air-conditioning capacity was observed.

A strategy for oxygen conditioning at high altitude: comparison with air conditioning.

PubMed

West, John B

2015-09-15

Large numbers of people live or work at high altitude, and many visit to trek or ski. The inevitable hypoxia impairs physical working capacity, and at higher altitudes there is also cognitive impairment. Twenty years ago oxygen enrichment of room air was introduced to reduce the hypoxia, and this is now used in dormitories, hotels, mines, and telescopes. However, recent advances in technology now allow large amounts of oxygen to be obtained from air or cryogenic oxygen sources. As a result it is now feasible to oxygenate large buildings and even institutions such as hospitals. An analogy can be drawn between air conditioning that has improved the living and working conditions of millions of people who live in hot climates and oxygen conditioning that can do the same at high altitude. Oxygen conditioning is similar to air conditioning except that instead of cooling the air, the oxygen concentration is raised, thus reducing the equivalent altitude. Oxygen conditioning on a large scale could transform living and working conditions at high altitude, where it could be valuable in homes, hospitals, schools, dormitories, company headquarters, banks, and legislative settings. Copyright © 2015 the American Physiological Society.

U.S. Light-duty Vehicle Air Conditioning Fuel Use and the Impact of Four Solar/Thermal Control Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rugh, John P; Kekelia, Bidzina; Kreutzer, Cory J

The U.S. uses 7.6 billion gallons of fuel per year for vehicle air conditioning (A/C), equivalent to 5.7 percent of the total national light-duty vehicle (LDV) fuel use. This equates to 30 gallons/year per vehicle, or 23.5 grams (g) of carbon dioxide (CO2) per mile, for an average U.S. vehicle. A/C is a significant contribution to national fuel use; therefore, technologies that reduce A/C loads may reduce operational costs, A/C fuel use, and CO2 emissions. Since A/C is not operated during standard EPA fuel economy testing protocols, EPA provides off-cycle credits to encourage OEMs to implement advanced A/C technologies thatmore » reduce fuel use in the real world. NREL researchers assessed thermal/solar off-cycle credits available in the U.S. Environmental Protection Agency's (EPA's) Final Rule for Model Year 2017 and Later Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy. Credits include glazings, solar reflective paint, and passive and active cabin ventilation. Implementing solar control glass reduced CO2 emissions by 2.0 g/mi, and solar reflective paint resulted in a reduction of 0.8 g/mi. Active and passive ventilation strategies only reduced emissions by 0.1 and 0.2 g/mi, respectively. The national-level analysis process is powerful and general; it can be used to determine the impact of a wide range of new vehicle thermal technologies on fuel use, EV range, and CO2 emissions.« less

Correlates of hot day air-conditioning use among middle-aged and older adults with chronic heart and lung diseases: the role of health beliefs and cues to action.

PubMed

Richard, Lucie; Kosatsky, Tom; Renouf, Annie

2011-02-01

Extreme ambient heat is a serious public health threat, especially for the elderly and persons with pre-existing health conditions. Although much of the excess mortality and morbidity associated with extreme heat is preventable, the adoption of effective preventive strategies is limited. The study reported here tested the predictive power of selected components of the Health Belief Model for air-conditioning (AC) use among 238 non-institutionalized middle-aged and older adults with chronic heart failure and/or chronic obstructive pulmonary disease living in Montréal, Canada. Respondents were recruited through clinics (response rate 71%) and interviews were conducted in their homes or by telephone. Results showed that 73% of participants reported having a home air conditioner. The average number of hours spent per 24-hour period in air-conditioned spaces during heat waves was 14.5 hours (SD = 9.4). Exploratory structural equation modeling showed that specific beliefs about the benefits of and drawbacks to AC as well as internal cues to action were predictive of its level of use, whereas the perceived severity of the effects of heat on health was not. The findings are discussed in light of the need to adequately support effective response to extreme heat in this vulnerable population.

Refrigeration, Heating & Air Conditioning. Post Secondary Curriculum Guide.

ERIC Educational Resources Information Center

Garrison, Joe C.; And Others

This curriculum guide was designed for use in postsecondary refrigeration, heating and air conditioning education programs in Georgia. Its purpose is to provide for the development of entry level skills in refrigeration, heating, and air conditioning in the areas of air conditioning knowledge, theoretical structure, tool usage, diagnostic ability,…

Air Conditioning. FOS: Fundamentals of Service.

ERIC Educational Resources Information Center

Employment and Training Administration (DOL), Washington, DC. Office of Youth Programs.

This manual on air conditioning is one of a series of power mechanics texts and visual aids covering theory of operation, diagnosis, and repair. Information is presented for use by vocational students and teachers as well as shop servicemen and laymen. Focus is on air conditioning systems for mobile machines, but most of the information also…

Measurement of Vehicle Air Conditioning Pull-Down Period

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, John F.; Huff, Shean P.; Moore, Larry G.

2016-08-01

Air conditioner usage was characterized for high heat-load summer conditions during short driving trips using a 2009 Ford Explorer and a 2009 Toyota Corolla. Vehicles were parked in the sun with windows closed to allow the cabin to become hot. Experiments were conducted by entering the instrumented vehicles in this heated condition and driving on-road with the windows up and the air conditioning set to maximum cooling, maximum fan speed and the air flow setting to recirculate cabin air rather than pull in outside humid air. The main purpose was to determine the length of time the air conditioner systemmore » would remain at or very near maximum cooling power under these severe-duty conditions. Because of the variable and somewhat uncontrolled nature of the experiments, they serve only to show that for short vehicle trips, air conditioning can remain near or at full cooling capacity for 10-minutes or significantly longer and the cabin may be uncomfortably warm during much of this time.« less

Application of solar energy to air-conditioning

NASA Technical Reports Server (NTRS)

Harstad, A. J.; Nash, J. M.

1978-01-01

Results of survey of application of solar energy to air-conditioning systems are summarized in report. Survey reviewed air-conditioning techniques that are most likely to find residential applications and that are compatible with solar-energy systems being developed.

Air conditioning system and component therefore distributing air flow from opposite directions

NASA Technical Reports Server (NTRS)

Obler, H. D.; Bauer, H. B. (Inventor)

1974-01-01

The air conditioning system comprises a plurality of separate air conditioning units coupled to a common supply duct such that air may be introduced into the supply duct in two opposite flow directions. A plurality of outlets such as registers or auxiliary or branch ducts communicate with the supply duct and valve means are disposed in the supply duct at at least some of the outlets for automatically channelling a controllable amount of air from the supply duct to the associated outlet regardless of the direction of air flow within the supply duct. The valve means comprises an automatic air volume control apparatus for distribution within the air supply duct into which air may be introduced from two opposite directions. The apparatus incorporates a freely swinging movable vane in the supply duct to automatically channel into the associated outlet only the deflected air flow which has the higher relative pressure.

IN2 Profile: 7AC Technologies Takes High-Efficiency Air Conditioning to a New Level

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozubal, Eric; Swan, Jed; Luttik, Peter

As part of the Wells Fargo Innovation Incubator (IN²) program, 7AC Technologies has developed a liquid desiccant evaporative technology that will result in a 40-50% energy savings for commercial buildings. The IN² program launched in October 2014 and is part of Wells Fargo’s 2020 Environmental Commitment to provide $100 million to environmentally-focused nonprofits and universities. The goal is to create an ecosystem that fosters and accelerates the commercialization of promising commercial buildings technologies that can provide scalable solutions to reduce the energy impact of buildings. According to the Department of Energy, nearly 40 percent of energy consumption in the U.S.more » today comes from buildings at an estimated cost of $413 billion.« less

Development of an in-line filter to prevent intrusion of NO2 toxic vapors into A/C systems

NASA Technical Reports Server (NTRS)

Meneghelli, Barry; Mcnulty, R. J.; Springer, Mike; Lueck, Dale E.

1995-01-01

The hypergolic propellant nitrogen tetroxide (N2O4 or NTO) is routinely used in spacecraft launched at Kennedy Space Center (KSC) and Cape Canaveral Air Station (CCAS). In the case of a catastrophic failure of the spacecraft, there would be a release of the unspent propellant in the form of a toxic cloud. Inhalation of this material at downwind concentrations which may be as high as 20 parts per million (ppm) for 30 minutes in duration, may produce irritation to the eyes, nose and respiratory tract. Studies at both KSC and CCAS have shown that the indoor concentrations of N2O4 during a toxic release may range from 1 to 15 ppm and depend on the air change rate (ACR) for a particular building and whether or not the air conditioning (A/C) system has been shut down or left in an operating mode. This project was initiated in order to assess how current A/C systems could be easily modified to prevent personnel from being exposed to toxic vapors. A sample system has been constructed to test the ability of several types of filter material to capture the N2O4 vapors prior to their infiltration into the A/C system. Test results will be presented which compare the efficiencies of standard A/C filters, water wash systems, and chemically impregnated filter material in taking toxic vapors out of the incoming air stream.

Deaths Due to Accidental Air Conditioner Compressor Explosion: A Case Series.

PubMed

Behera, Chittaranjan; Bodwal, Jatin; Sikary, Asit K; Chauhan, Mohit Singh; Bijarnia, Manjul

2017-01-01

In an air-conditioning system, the compressor is a large electric pump that pressurizes the refrigerant gas as part of the process of turning it back into a liquid. The explosion of an air conditioner (AC) compressor is an uncommon event, and immediate death resulted from the blast effect is not reported in forensic literature. We report three such cases in which young AC mechanics were killed on the spot due to compressor blast, while repairing the domestic split AC unit. The autopsy findings, the circumstances leading to the explosion of the compressor, are discussed in this study. © 2016 American Academy of Forensic Sciences.

Pulmonary functions in air conditioner users.

PubMed

Khaliq, Farah; Sharma, Sameer; Tandon, O P

2006-01-01

Air conditioning may affect human health since it has profound effect on our environment, than just lowering temperature. The present study was planned to assess the effect of air conditioners (AC) on pulmonary functions in young healthy non-smoker males. The study group comprised of ten subjects who were using AC's in their cars for at least 1 hr daily since last 6 months. While ten subjects who did not use AC at all served as controls. The pulmonary functions were assessed using PK Morgan 232 spirometer in a closed room. The peak expiratory flow rate (PEFR) and Forced expiratory flow between 25-75% of vital capacity (FEF25-75) were significantly reduced in subjects using car AC's. Inspiratory flow rates also showed a trend towards decline in AC users but could not reach the level of significance. The lung volumes and capacities were not significantly different in the two groups except for forced expiratory volume in 0.5 sec (FEV 0.5 sec), which also decreased in AC users. The airway resistance and lung compliance did not show significant change. In the presence of normal FEV1, reduced FEF25-75% which is the flow rate over the middle half of vital capacity, is an evidence of mild airflow limitation. The result is suggestive of predisposition of AC users towards respiratory disorders in form of mild airflow restriction.

The microbiological quality of air improves when using air conditioning systems in cars.

PubMed

Vonberg, Ralf-Peter; Gastmeier, Petra; Kenneweg, Björn; Holdack-Janssen, Hinrich; Sohr, Dorit; Chaberny, Iris F

2010-06-01

Because of better comfort, air conditioning systems are a common feature in automobiles these days. However, its impact on the number of particles and microorganisms inside the vehicle--and by this its impact on the risk of an allergic reaction--is yet unknown. Over a time period of 30 months, the quality of air was investigated in three different types of cars (VW Passat, VW Polo FSI, Seat Alhambra) that were all equipped with a automatic air conditioning system. Operation modes using fresh air from outside the car as well as circulating air from inside the car were examined. The total number of microorganisms and the number of mold spores were measured by impaction in a high flow air sampler. Particles of 0.5 to 5.0 microm diameter were counted by a laser particle counter device. Overall 32 occasions of sampling were performed. The concentration of microorganisms outside the cars was always higher than it was inside the cars. Few minutes after starting the air conditioning system the total number of microorganisms was reduced by 81.7%, the number of mold spores was reduced by 83.3%, and the number of particles was reduced by 87.8%. There were no significant differences neither between the types of cars nor between the types of operation mode of the air conditioning system (fresh air vs. circulating air). All parameters that were looked for in this study improved during utilization of the car's air conditioning system. We believe that the risk of an allergic reaction will be reduced during use also. Nevertheless, we recommend regular maintenance of the system and replacement of older filters after defined changing intervals.

Air quality and passenger comfort in an air-conditioned bus micro-environment.

PubMed

Zhu, Xiaoxuan; Lei, Li; Wang, Xingshen; Zhang, Yinghui

2018-04-12

In this study, passenger comfort and the air pollution status of the micro-environmental conditions in an air-conditioned bus were investigated through questionnaires, field measurements, and a numerical simulation. As a subjective analysis, passengers' perceptions of indoor environmental quality and comfort levels were determined from questionnaires. As an objective analysis, a numerical simulation was conducted using a discrete phase model to determine the diffusion and distribution of pollutants, including particulate matter with a diameter < 10 μm (PM 10 ), which were verified by experimental results. The results revealed poor air quality and dissatisfactory thermal comfort conditions in Jinan's air-conditioned bus system. To solve these problems, three scenarios (schemes A, B, C) were designed to alter the ventilation parameters. According to the results of an improved simulation of these scenarios, reducing or adding air outputs would shorten the time taken to reach steady-state conditions and weaken the airflow or lower the temperature in the cabin. The airflow pathway was closely related to the layout of the air conditioning. Scheme B lowered the temperature by 0.4 K and reduced the airflow by 0.01 m/s, while scheme C reduced the volume concentration of PM 10 to 150 μg/m 3 . Changing the air supply angle could further improve the airflow and reduce the concentration of PM 10 . With regard to the perception of airflow and thermal comfort, the scheme with an airflow provided by a 60° nozzle was considered better, and the concentration of PM 10 was reduced to 130 μg/m 3 .

Air regenerating and conditioning

NASA Technical Reports Server (NTRS)

Grishayenkov, B. G.

1975-01-01

Various physicochemical methods of regenerating and conditioning air for spacecraft are described with emphasis on conditions which affect efficiency of the system. Life support systems used in closed, hermetically sealed environments are discussed with references to actual application in the Soviet Soyuz and Voskhod manned spacecraft. Temperature and humidity control, removal of carbon dioxide, oxygen regeneration, and removal of bacteria and viruses are among the factors considered.

The microbiological quality of air improves when using air conditioning systems in cars

PubMed Central

2010-01-01

Background Because of better comfort, air conditioning systems are a common feature in automobiles these days. However, its impact on the number of particles and microorganisms inside the vehicle - and by this its impact on the risk of an allergic reaction - is yet unknown. Methods Over a time period of 30 months, the quality of air was investigated in three different types of cars (VW Passat, VW Polo FSI, Seat Alhambra) that were all equipped with a automatic air conditioning system. Operation modes using fresh air from outside the car as well as circulating air from inside the car were examined. The total number of microorganisms and the number of mold spores were measured by impaction in a high flow air sampler. Particles of 0.5 to 5.0 μm diameter were counted by a laser particle counter device. Results Overall 32 occasions of sampling were performed. The concentration of microorganisms outside the cars was always higher than it was inside the cars. Few minutes after starting the air conditioning system the total number of microorganisms was reduced by 81.7%, the number of mold spores was reduced by 83.3%, and the number of particles was reduced by 87.8%. There were no significant differences neither between the types of cars nor between the types of operation mode of the air conditioning system (fresh air vs. circulating air). All parameters that were looked for in this study improved during utilization of the car's air conditioning system. Conclusions We believe that the risk of an allergic reaction will be reduced during use also. Nevertheless, we recommend regular maintenance of the system and replacement of older filters after defined changing intervals. PMID:20515449

40 CFR 86.165-12 - Air conditioning idle test procedure.

Code of Federal Regulations, 2010 CFR

2010-07-01

... at idle when CO2 emissions are measured without any air conditioning systems operating, followed by a ten-minute period at idle when CO2 emissions are measured with the air conditioning system operating... section, turn on the vehicle's air conditioning system. Set automatic air conditioning systems to a...

Effect of a single injection of autologous conditioned serum (ACS) on tendon healing in equine naturally occurring tendinopathies.

PubMed

Geburek, Florian; Lietzau, Maren; Beineke, Andreas; Rohn, Karl; Stadler, Peter M

2015-06-26

Autologous blood-derived biologicals, including autologous conditioned serum (ACS), are frequently used to treat tendinopathies in horses despite limited evidence for their efficacy. The purpose of this study was to describe the effect of a single intralesional injection of ACS in naturally occurring tendinopathies of the equine superficial digital flexor tendon (SDFT) on clinical, ultrasonographic, and histological parameters. Fifteen horses with 17 naturally occurring tendinopathies of forelimb SDFTs were examined clinically and ultrasonographically (day 0). Injured tendons were randomly assigned to the ACS-treated group (n = 10) receiving a single intralesional ACS injection or included as controls (n = 7) which were either untreated or injected with saline on day 1. All horses participated in a gradually increasing exercise programme and were re-examined nine times at regular intervals until day 190. Needle biopsies were taken from the SDFTs on days 0, 36 and 190 and examined histologically and for the expression of collagen types I and III by immunohistochemistry. In ACS-treated limbs lameness decreased significantly until day 10 after treatment. Swelling (scores) of the SDFT region decreased within the ACS group between 50 and 78 days after treatment. Ultrasonographically, the percentage of the lesion in the tendon was significantly lower and the echogenicity of the lesion (total echo score) was significantly higher 78 and 106 days after intralesional ACS injection compared to controls. Histology revealed that, compared to controls, tenocyte nuclei were more spindle-shaped 36 days after ACS injection. Immunohistochemistry showed that collagen type I expression significantly increased between days 36 and 190 after ACS injection. Single intralesional ACS injection of equine SDFTs with clinical signs of acute tendinopathy contributes to an early significant reduction of lameness and leads to temporary improvement of ultrasonographic parameters of repair tissue

DC and AC conductivity properties of bovine dentine hydroxyapatite (BDHA)

NASA Astrophysics Data System (ADS)

Dumludag, F.; Gunduz, O.; Kılıc, O.; Ekren, N.; Kalkandelen, C.; Ozbek, B.; Oktar, F. N.

2017-12-01

Bovine dentine bio-waste may be used as a potential natural source of hydroxyapatite (BDHA), thus extraction of bovine dentin hydroxyapatite (BDHA) from bio-waste is significantly important to fabricate in a simple, economically and environmentally preferable. DC and AC conductivity properties of BDHA were investigated depending on sintering temperature (1000ºC - 1300°C) in air and vacuum (<10-2 mbar) ambient at room temperature. DC conductivity measurements performed between -1 and 1 V. AC conductivity measurements performed in the frequency range of 40 Hz - 100 kHz. DC conductivity results showed that dc conductivity values of the BDHA decrease with increasing sintering temperature in air ambient. It is not observed remarkable/systematic behavior for ac conductivity depending on sintering temperature.

Benefits of Leapfrogging to Superefficiency and Low Global Warming Potential Refrigerants in Room Air Conditioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Nihar; Wei, Max; Letschert, Virginie

2015-10-01

with emissions and growth projections, moving to efficient room air conditioning (~30% more efficient than current technology) in parallel with low-GWP refrigerants in room air conditioning could avoid up to ~25 billion tonnes of CO2 in 2030, ~33 billion in 2040, and ~40 billion in 2050, i.e. cumulative savings up to 98 billion tonnes of CO2 by 2050. Therefore, superefficient room ACs using low-GWP refrigerants merit serious consideration to maximize peak load reduction and GHG savings.« less

Reduced bleed air extraction for DC-10 cabin air conditioning

NASA Technical Reports Server (NTRS)

Newman, W. H.; Viele, M. R.; Hrach, F. J.

1980-01-01

It is noted that a significant fuel savings can be achieved by reducing bleed air used for cabin air conditioning. Air in the cabin can be recirculated to maintain comfortable ventilation rates but the quality of the air tends to decrease due to entrainment of smoke and odors. Attention is given to a development system designed and fabricated under the NASA Engine Component Improvement Program to define the recirculation limit for the DC-10. It is shown that with the system, a wide range of bleed air reductions and recirculation rates is possible. A goal of 0.8% fuel savings has been achieved which results from a 50% reduction in bleed extraction from the engine.

Air conditioning system with supplemental ice storing and cooling capacity

DOEpatents

Weng, Kuo-Lianq; Weng, Kuo-Liang

1998-01-01

The present air conditioning system with ice storing and cooling capacity can generate and store ice in its pipe assembly or in an ice storage tank particularly equipped for the system, depending on the type of the air conditioning system. The system is characterized in particular in that ice can be produced and stored in the air conditioning system whereby the time of supplying cooled air can be effectively extended with the merit that the operation cycle of the on and off of the compressor can be prolonged, extending the operation lifespan of the compressor in one aspect. In another aspect, ice production and storage in great amount can be performed in an off-peak period of the electrical power consumption and the stored ice can be utilized in the peak period of the power consumption so as to provide supplemental cooling capacity for the compressor of the air conditioning system whereby the shift of peak and off-peak power consumption can be effected with ease. The present air conditioning system can lower the installation expense for an ice-storing air conditioning system and can also be applied to an old conventional air conditioning system.

ARC-1978-AC78-1040-172

NASA Image and Video Library

1978-11-14

Lockheed YO-3A (USA 69-18010 NASA 718) A/C & BELL COBRA HELICOPTER FLIGHT & GROUND TESTS AT EDWARDS AIR FORCE BASE. Rotorcraft Research. NASA SP-1998-3300 Flight Research at Ames: 57 Years of Development and Validation of Aeronautical Technology Fig. 143

Residential air-conditioning and climate change: voices of the vulnerable.

PubMed

Farbotko, Carol; Waitt, Gordon

2011-12-01

Decreasing the risk of heat-stress is an imperative in health promotion, and is widely accepted as necessary for successful adaptation to climate change. Less well understood are the vulnerabilities that air-conditioning use exacerbates, and conversely, the need for the promotion of alternative strategies for coping with heat wave conditions. This paper considers these issues with a focus on the role of air-conditioning in the everyday life of elderly public housing tenants living alone, a sector of the population that has been identified as being at high risk of suffering heat stress. A vulnerability analysis of domestic air-conditioning use, drawing on literature and policy on air-conditioning practices and ethnographic research with households. Residential air-conditioning exacerbated existing inequities. Case studies of two specifically selected low-income elderly single person households revealed that such households were unlikely to be able to afford this 'solution' to increasing exposure to heat waves in the absence of energy subsidies. Residential air-conditioning use during heat waves caused unintended side-effects, such as system-wide blackouts, which, in turn, led to escalating electricity costs as power companies responded by upgrading infrastructure to cope with periods of excess demand. Air-conditioning also contributed to emissions that cause climate change. Residential air-conditioning is a potentially maladaptive technology for reducing the risk of heat stress.

Transient AC voltage related phenomena for HVDC schemes connected to weak AC systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pilotto, L.A.S.; Szechtman, M.; Hammad, A.E.

1992-07-01

In this paper a didactic explanation of voltage stability associated phenomena at HVDC terminals is presented. Conditions leading to ac voltage collapse problems are identified. A mechanism that excites control-induced voltage oscillations is shown. The voltage stability factor is used for obtaining the maximum power limits of ac/dc systems operating with different control strategies. Correlation to Pd {times} Id curves is given. Solutions for eliminating the risks of voltage collapse and for avoiding control-induced oscillations are discussed. The results are supported by detailed digital simulations of a weak ac/dc system using EMTP.

Air Conditioning and Refrigeration Program Articulation, 1981-1982.

ERIC Educational Resources Information Center

Dallas County Community Coll. District, TX.

Based on a survey of high school programs and courses in the Dallas County Community College District (DCCCD), this articulated program is designed to prepare students for entry-level employment in the air conditioning and refrigeration industry, including residential and commercial air conditioning and commercial refrigeration. The skills and…

Design and demonstration of a storage assisted air conditioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avril, F.; Irvine, T.F.

1982-04-01

The report describes the design and demonstration of a storage-assisted air conditioning system for residential central air conditioning applications. The system was designed to reduce peak air conditioning loads by storing coolness to fulfill daytime air conditioning requirements. The system design analyses, as well as performance data obtained from a residential installation on Long Island, are presented, along with an economic evaluation of the system. The results of the study indicate that such a system can reduce air conditioning peak load requirements while maintaining house temperature and humidity within prescribed limits. However, further system optimization is required, as well asmore » either equipment costs reduction or increased incentives, to make this system economically attractive for use in New York State.« less

40 CFR 86.165-12 - Air conditioning idle test procedure.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Applicability. This section describes procedures for determining air conditioning-related CO2 emissions from... used to qualify for air conditioning efficiency CO2 credits according to § 86.1866-12(c). (b) Overview... at idle when CO2 emissions are measured without any air conditioning systems operating, followed by a...

40 CFR 86.165-12 - Air conditioning idle test procedure.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Applicability. This section describes procedures for determining air conditioning-related CO2 emissions from... used to qualify for air conditioning efficiency CO2 credits according to § 86.1866-12(c). (b) Overview... at idle when CO2 emissions are measured without any air conditioning systems operating, followed by a...

40 CFR 86.165-12 - Air conditioning idle test procedure.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Applicability. This section describes procedures for determining air conditioning-related CO2 emissions from... used to qualify for air conditioning efficiency CO2 credits according to § 86.1866-12(c). (b) Overview... at idle when CO2 emissions are measured without any air conditioning systems operating, followed by a...

40 CFR 86.165-12 - Air conditioning idle test procedure.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Applicability. This section describes procedures for determining air conditioning-related CO2 emissions from... used to qualify for air conditioning efficiency CO2 credits according to § 86.1866-12(c). (b) Overview... at idle when CO2 emissions are measured without any air conditioning systems operating, followed by a...

The AC photovoltaic module is here!

NASA Astrophysics Data System (ADS)

Strong, Steven J.; Wohlgemuth, John H.; Wills, Robert H.

1997-02-01

This paper describes the design, development, and performance results of a large-area photovoltaic module whose electrical output is ac power suitable for direct connection to the utility grid. The large-area ac PV module features a dedicated, integrally mounted, high-efficiency dc-to-ac power inverter with a nominal output of 250 watts (STC) at 120 Vac, 60 H, that is fully compatible with utility power. The module's output is connected directly to the building's conventional ac distribution system without need for any dc wiring, string combiners, dc ground-fault protection or additional power-conditioning equipment. With its advantages, the ac photovoltaic module promises to become a universal building block for use in all utility-interactive PV systems. This paper discusses AC Module design aspects and utility interface issues (including islanding).

Numerical simulation and nasal air-conditioning

PubMed Central

Keck, Tilman; Lindemann, Jörg

2011-01-01

Heating and humidification of the respiratory air are the main functions of the nasal airways in addition to cleansing and olfaction. Optimal nasal air conditioning is mandatory for an ideal pulmonary gas exchange in order to avoid desiccation and adhesion of the alveolar capillary bed. The complex three-dimensional anatomical structure of the nose makes it impossible to perform detailed in vivo studies on intranasal heating and humidification within the entire nasal airways applying various technical set-ups. The main problem of in vivo temperature and humidity measurements is a poor spatial and time resolution. Therefore, in vivo measurements are feasible only to a restricted extent, solely providing single temperature values as the complete nose is not entirely accessible. Therefore, data on the overall performance of the nose are only based on one single measurement within each nasal segment. In vivo measurements within the entire nose are not feasible. These serious technical issues concerning in vivo measurements led to a large number of numerical simulation projects in the last few years providing novel information about the complex functions of the nasal airways. In general, numerical simulations merely calculate predictions in a computational model, e.g. a realistic nose model, depending on the setting of the boundary conditions. Therefore, numerical simulations achieve only approximations of a possible real situation. The aim of this review is the synopsis of the technical expertise on the field of in vivo nasal air conditioning, the novel information of numerical simulations and the current state of knowledge on the influence of nasal and sinus surgery on nasal air conditioning. PMID:22073112

MOBILE AIR-CONDITIONING RECYCLING MANUAL

EPA Science Inventory

The report gives guidelines on the recovery and recycle of the chlorofluorocarbon (CFC), dichlorodifluoromethane (CFC-12), from mobile air conditions. It is intended for wide distribution internationally and is especially for use by developing countries and the World Bank to ass...

[Air quality control systems: heating, ventilating, and air conditioning (HVAC)].

PubMed

Bellucci Sessa, R; Riccio, G

2004-01-01

After a brief illustration of the principal layout schemes of Heating, Ventilating, and Air Conditioning (HVAC), the first part of this paper summarizes the standards, both voluntary and compulsory, regulating HVAC facilities design and installation with regard to the question of Indoor Air Quality (IAQ). The paper then examines the problem of ventilation systems maintenance and the essential hygienistic requirements in whose absence HVAC facilities may become a risk factor for people working or living in the building. Lastly, the paper deals with HVAC design strategies and methods, which aim not only to satisfy comfort and air quality requirements, but also to ensure easy and effective maintenance procedures.

The effect of heat treatment and test parameters on the aqueous stress corrosion cracking of D6AC steel

NASA Technical Reports Server (NTRS)

Gilbreath, W. P.; Adamson, M. J.

1974-01-01

The crack growth behavior of D6AC steel as a function of stress intensity, stress and corrosion history and test technique, under sustained load in natural seawater, 3.3 percent NaCl solution, distilled water, and high humidity air was investigated. Reported investigations of D6AC were considered with emphasis on thermal treatment, specimen configuration, fracture toughness, crack-growth rates, initiation period, threshold, and the extension of corrosion fatigue data to sustained load conditions. Stress history effects were found to be most important in that they controlled incubation period, initial crack growth rates, and apparent threshold.

Application of solar energy to air conditioning systems

NASA Technical Reports Server (NTRS)

Nash, J. M.; Harstad, A. J.

1976-01-01

The results of a survey of solar energy system applications of air conditioning are summarized. Techniques discussed are both solar powered (absorption cycle and the heat engine/Rankine cycle) and solar related (heat pump). Brief descriptions of the physical implications of various air conditioning techniques, discussions of status, proposed technological improvements, methods of utilization and simulation models are presented, along with an extensive bibliography of related literature.

Mountain Plains Learning Experience Guide: Heating, Refrigeration, & Air Conditioning.

ERIC Educational Resources Information Center

Carey, John

This Heating, Refrigeration, and Air Conditioning course is comprised of eleven individualized units: (1) Refrigeration Tools, Materials, and Refrigerant; (2) Basic Heating and Air Conditioning; (3) Sealed System Repairs; (4) Basic Refrigeration Systems; (5) Compression Systems and Compressors; (6) Refrigeration Controls; (7) Electric Circuit…

A dry-cooled AC quantum voltmeter

NASA Astrophysics Data System (ADS)

Schubert, M.; Starkloff, M.; Peiselt, K.; Anders, S.; Knipper, R.; Lee, J.; Behr, R.; Palafox, L.; Böck, A. C.; Schaidhammer, L.; Fleischmann, P. M.; Meyer, H.-G.

2016-10-01

The paper describes a dry-cooled AC quantum voltmeter system operated up to kilohertz frequencies and 7 V rms. A 10 V programmable Josephson voltage standard (PJVS) array was installed on a pulse tube cooler (PTC) driven with a 4 kW air-cooled compressor. The operating margins at 70 GHz frequencies were investigated in detail and found to exceed 1 mA Shapiro step width. A key factor for the successful chip operation was the low on-chip power consumption of 65 mW in total. A thermal interface between PJVS chip and PTC cold stage was used to avoid a significant chip overheating. By installing the cryocooled PJVS array into an AC quantum voltmeter setup, several calibration measurements of dc standards and calibrator ac voltages up to 2 kHz frequencies were carried out to demonstrate the full functionality. The results are discussed and compared to systems with standard liquid helium cooling. For dc voltages, a direct comparison measurement between the dry-cooled AC quantum voltmeter and a liquid-helium based 10 V PJVS shows an agreement better than 1 part in 1010.

Apparatus for supplying conditioned air at a substantially constant temperature and humidity

NASA Technical Reports Server (NTRS)

Obler, H. D. (Inventor)

1980-01-01

The apparatus includes a supply duct coupled to a source of supply air for carrying the supply air therethrough. A return duct is coupled to the supply duct for carrying return conditioned air therethrough. A temperature reducing device is coupled to the supply duct for decreasing the temperature of the supply and return conditioned air. A by-pass duct is coupled to the supply duct for selectively directing portions of the supply and return conditioned air around the temperature reducing device. Another by-pass duct is coupled to the return duct for selectively directing portions of the return conditioned air around the supply duct and the temperature reduction device. Controller devices selectively control the flow and amount of mixing of the supply and return conditioned air.

Calibrating Physical Parameters in House Models Using Aggregate AC Power Demand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yannan; Stevens, Andrew J.; Lian, Jianming

For residential houses, the air conditioning (AC) units are one of the major resources that can provide significant flexibility in energy use for the purpose of demand response. To quantify the flexibility, the characteristics of all the houses need to be accurately estimated, so that certain house models can be used to predict the dynamics of the house temperatures in order to adjust the setpoints accordingly to provide demand response while maintaining the same comfort levels. In this paper, we propose an approach using the Reverse Monte Carlo modeling method and aggregate house models to calibrate the distribution parameters ofmore » the house models for a population of residential houses. Given the aggregate AC power demand for the population, the approach can successfully estimate the distribution parameters for the sensitive physical parameters based on our previous uncertainty quantification study, such as the mean of the floor areas of the houses.« less

Heating, Ventilation, and Air Conditioning Series. Duty Task List.

ERIC Educational Resources Information Center

Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This task list is intended for use in planning and/or evaluating a competency-based course in heating, ventilation, and air conditioning. The guide outlines the tasks entailed in eight different duties typically required of employees in the following occupations: residential installer, domestic refrigeration technician, air conditioning and…

Alternating current (AC) iontophoretic transport across human epidermal membrane: effects of AC frequency and amplitude.

PubMed

Yan, Guang; Xu, Qingfang; Anissimov, Yuri G; Hao, Jinsong; Higuchi, William I; Li, S Kevin

2008-03-01

As a continuing effort to understand the mechanisms of alternating current (AC) transdermal iontophoresis and the iontophoretic transport pathways in the stratum corneum (SC), the objectives of the present study were to determine the interplay of AC frequency, AC voltage, and iontophoretic transport of ionic and neutral permeants across human epidermal membrane (HEM) and use AC as a means to characterize the transport pathways. Constant AC voltage iontophoresis experiments were conducted with HEM in 0.10 M tetraethyl ammonium pivalate (TEAP). AC frequencies ranging from 0.0001 to 25 Hz and AC applied voltages of 0.5 and 2.5 V were investigated. Tetraethyl ammonium (TEA) and arabinose (ARA) were the ionic and neutral model permeants, respectively. In data analysis, the logarithm of the permeability coefficients of HEM for the model permeants was plotted against the logarithm of the HEM electrical resistance for each AC condition. As expected, linear correlations between the logarithms of permeability coefficients and the logarithms of resistances of HEM were observed, and the permeability data were first normalized and then compared at the same HEM electrical resistance using these correlations. Transport enhancement of the ionic permeant was significantly larger than that of the neutral permeant during AC iontophoresis. The fluxes of the ionic permeant during AC iontophoresis of 2.5 V in the frequency range from 5 to 1,000 Hz were relatively constant and were approximately 4 times over those of passive transport. When the AC frequency decreased from 5 to 0.001 Hz at 2.5 V, flux enhancement increased to around 50 times over passive transport. While the AC frequency for achieving the full effect of iontophoretic enhancement at low AC frequency was lower than anticipated, the frequency for approaching passive diffusion transport at high frequency was higher than expected from the HEM morphology. These observations are consistent with a transport model of multiple

[Simulation and air-conditioning in the nose].

PubMed

Keck, T; Lindemann, J

2010-05-01

Heating and humidification of the respiratory air are the main functions of the nasal airways in addition to cleansing and olfaction. Optimal nasal air conditioning is mandatory for an ideal pulmonary gas exchange in order to avoid dessication and adhesion of the alveolar capillary bed. The complex three-dimensional anatomical structure of the nose makes it impossible to perform detailed in vivo studies on intranasal heating and humidification within the entire nasal airways applying various technical set-ups. The main problem of in vivo temperature and humidity measurements is a poor spatial and time resolution. Therefore, in vivo measurements are feasible to a restricted extent, only providing single temperature values as the complete nose is not entirely accessible. Therefore, data on the overall performance of the nose are only based on one single measurement within each nasal segment. In vivo measurements within the entire nose are not feasible. These serious technical issues concerning in vivo measurements led to a large number of numerical simulation projects in the last few years providing novel information about the complex functions of the nasal airways. In general, numerical simulations only calculate predictions in a computational model, e. g. realistic nose model, depending on the setting of the boundary conditions. Therefore, numerical simulations achieve only approximations of a possible real situation. The aim of this report is the synopsis of the technical expertise on the field of in vivo nasal air conditioning, the novel information of numerical simulations and the current state of knowledge on the influence of nasal and sinus surgery on nasal air conditioning.

Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo

PubMed Central

Nishimura, Takeshi; Mori, Futoshi; Hanida, Sho; Kumahata, Kiyoshi; Ishikawa, Shigeru; Samarat, Kaouthar; Miyabe-Nishiwaki, Takako; Hayashi, Misato; Tomonaga, Masaki; Suzuki, Juri; Matsuzawa, Tetsuro; Matsuzawa, Teruo

2016-01-01

We are flat-faced hominins with an external nose that protrudes from the face. This feature was derived in the genus Homo, along with facial flattening and reorientation to form a high nasal cavity. The nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. In this study, we used computational fluid dynamics (CFD) with three-dimensional topology models of the nasal passage under the same simulation conditions, to investigate air-conditioning performance in humans, chimpanzees, and macaques. The CFD simulation showed a horizontal straight flow of inhaled air in chimpanzees and macaques, contrasting with the upward and curved flow in humans. The inhaled air is conditioned poorly in humans compared with nonhuman primates. Virtual modifications to the human external nose topology, in which the nasal vestibule and valve are modified to resemble those of chimpanzees, change the airflow to be horizontal, but have little influence on the air-conditioning performance in humans. These findings suggest that morphological variation of the nasal passage topology was only weakly sensitive to the ambient atmosphere conditions; rather, the high nasal cavity in humans was formed simply by evolutionary facial reorganization in the divergence of Homo from the other hominin lineages, impairing the air-conditioning performance. Even though the inhaled air is not adjusted well within the nasal cavity in humans, it can be fully conditioned subsequently in the pharyngeal cavity, which is lengthened in the flat-faced Homo. Thus, the air-conditioning faculty in the nasal passages was probably impaired in early Homo members, although they have survived successfully under the fluctuating climate of the Plio-Pleistocene, and then they moved “Out of Africa” to explore the more severe climates of

Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo.

PubMed

Nishimura, Takeshi; Mori, Futoshi; Hanida, Sho; Kumahata, Kiyoshi; Ishikawa, Shigeru; Samarat, Kaouthar; Miyabe-Nishiwaki, Takako; Hayashi, Misato; Tomonaga, Masaki; Suzuki, Juri; Matsuzawa, Tetsuro; Matsuzawa, Teruo

2016-03-01

We are flat-faced hominins with an external nose that protrudes from the face. This feature was derived in the genus Homo, along with facial flattening and reorientation to form a high nasal cavity. The nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. In this study, we used computational fluid dynamics (CFD) with three-dimensional topology models of the nasal passage under the same simulation conditions, to investigate air-conditioning performance in humans, chimpanzees, and macaques. The CFD simulation showed a horizontal straight flow of inhaled air in chimpanzees and macaques, contrasting with the upward and curved flow in humans. The inhaled air is conditioned poorly in humans compared with nonhuman primates. Virtual modifications to the human external nose topology, in which the nasal vestibule and valve are modified to resemble those of chimpanzees, change the airflow to be horizontal, but have little influence on the air-conditioning performance in humans. These findings suggest that morphological variation of the nasal passage topology was only weakly sensitive to the ambient atmosphere conditions; rather, the high nasal cavity in humans was formed simply by evolutionary facial reorganization in the divergence of Homo from the other hominin lineages, impairing the air-conditioning performance. Even though the inhaled air is not adjusted well within the nasal cavity in humans, it can be fully conditioned subsequently in the pharyngeal cavity, which is lengthened in the flat-faced Homo. Thus, the air-conditioning faculty in the nasal passages was probably impaired in early Homo members, although they have survived successfully under the fluctuating climate of the Plio-Pleistocene, and then they moved "Out of Africa" to explore the more severe climates of

Effects of suspension of air-conditioning on airtight-type racks.

PubMed

Kanzaki, M; Fujieda, M; Furukawa, T

2001-10-01

Although isolation racks are superior to open-type racks in terms of securing breeding conditions for laboratory animals, the contingency-proofing capability of the former has yet to be determined. Therefore, from the view of risk management, we studied the environmental change in isolation racks by forcibly suspending ventilation and air-conditioning and confirming the maximal time length for complete recovery to the original condition after restarting their operations. The isolation racks were placed in a room that was equipped with an independent air-conditioning system. When the inside condition of the racks reached 22-24 degrees C and 59-64% of relative humidity, the air-conditioning and ventilation were forcibly suspended and the subsequent temperature, relative humidity, ammonium and CO2 concentrations in the racks were measured over time. We found that after suspending the air-conditioning and ventilation, it took 40-60 min for temperature, and about 10 min for relative humidity to exceed the maximum values (temperature and relative humidity) referred to in the Showa 58 Nenban Guideline Jikken Doubutsu Shisetsu no Kenchiku oyobi Setsubi (Guidelines of buildings and facilities for experimental animals in Japan; Year 1983 edition). After 17 hr 25 min of the suspension of air-conditioning and ventilation, two rats were found dead. Then, the air-conditioning and ventilation were restarted. It took about 2 hr for temperature, and 50 min for relative humidity to regain the guideline values. The ammonium concentration stayed within the guideline value with a maximum concentration of 2 ppm in the experimental period, whereas the CO2 concentration was found to exceed 9% at the time of animal death.

Study on the design schemes of the air-conditioning system in a gymnasium

NASA Astrophysics Data System (ADS)

Zhang, Yujin; Wu, Xinwei; Zhang, Jing; Pan, Zhixin

2017-08-01

In view of designing the air conditioning project for a gymnasium successfully, the cooling and heating source schemes are fully studied by analyzing the surrounding environment and energy conditions of the project, as well as the analysis of the initial investment and operating costs, which indicates the air source heat pump air conditioning system is the best choice for the project. The indoor air conditioning schemes are also studied systematically and the optimization of air conditioning schemes is carried out in each area. The principle of operating conditions for the whole year is followed and the quality of indoor air and energy-saving are ensured by the optimized design schemes, which provide references for the air conditioning system design in the same kinds of building.

Performance analysis of an air drier for a liquid dehumidifier solar air conditioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Queiroz, A.G.; Orlando, A.F.; Saboya, F.E.M.

1988-05-01

A model was developed for calculating the operating conditions of a non-adiabatic liquid dehumidifier used in solar air conditioning systems. In the experimental facility used for obtaining the data, air and triethylene glycol circulate countercurrently outside staggered copper tubes which are the filling of an absorption tower. Water flows inside the copper tubes, thus cooling the whole system and increasing the mass transfer potential for drying air. The methodology for calculating the mass transfer coefficient is based on the Merkel integral approach, taking into account the lowering of the water vapor pressure in equilibrium with the water glycol solution.

Air conditioning systems as non-infectious health hazards inducing acute respiratory symptoms.

PubMed

Gerber, Alexander; Fischer, Axel; Willig, Karl-Heinz; Groneberg, David A

2006-04-01

Chronic and acute exposure to toxic aerosols belongs to frequent causes of airway diseases. However, asthma attacks due to long-distance inhalative exposure to organic solvents, transmitted via an air condition system, have not been reported so far. The present case illustrates the possibility of air conditioning systems as non-infectious health hazards in occupational medicine. So far, only infectious diseases such as legionella pneumophila pneumonia have commonly been associated to air-conditioning exposures but physicians should be alert to the potential of transmission of toxic volatile substances via air conditioning systems. In view of the events of the 11th of September 2001 with a growing danger of large building terrorism which may even use air conditioning systems to transmit toxins, facility management security staff should be alerted to possible non-infectious toxic health hazards arising from air-conditioning systems.

Small photovoltaic setup for the air conditioning system

NASA Astrophysics Data System (ADS)

Masiukiewicz, Maciej

2017-10-01

The increasing interest in air conditioning systems for residential applications in Poland will certainly increase the demand for electricity during the summer period. Due to this fact a growing interest in solutions that help to lower the electricity consumption in this sector is observed. The problem of increased energy demand for air conditioning purposes can be solved by transfer the consumption of electricity from the grid system to renewable energy sources (RES). The greatest demand for cooling occurs during the biggest sunlight. This is the basis for the analysis of technical power system based on photovoltaic cells (PV) to power the split type air conditioner. The object of the study was the commercial residential airconditioning inverter units with a capacity of 2.5kW. A network electricity production system for their own use with the possibility of buffering energy in batteries (OFF-GRID system). Currently, on the Polish market, there are no developed complete solutions dedicated to air conditioning systems based on PV. In Poland, solar energy is mainly used for heat production in solar collectors. The proposed solution will help to increase the popularity of PV systems in the Polish market as an alternative to other RES. The basic conclusion is that the amount of PV energy generated was sufficient to cover the daily energy requirement of the air conditioner.

EFFECT OF DRY AIR CHILLING ON WARNER-BRATZLER SHEAR FORCE AND WATER-HOLDING CAPACITY OF BROILER MEAT DEBONED FOUR HOURS POSTMORTEM

USDA-ARS?s Scientific Manuscript database

TECHNICAL ABSTRACT Advantages of air chilling (AC) methods over immersion chilling (IC) methods in quality retention and improvement of deboned chicken breast meat depends on experimental conditions, such as deboning time. The objective of this study was to evaluate the effect of a dry-AC method on ...

The Interaction Effects of Meteorological Factors and Air Pollution on the Development of Acute Coronary Syndrome

NASA Astrophysics Data System (ADS)

Huang, Ching-Hui; Lin, Heng-Cheng; Tsai, Chen-Dao; Huang, Hung-Kai; Lian, Ie-Bin; Chang, Chia-Chu

2017-03-01

This study investigated the interaction effects of meteorological factors and air pollutants on the onset of acute coronary syndrome (ACS). Data of ACS patients were obtained from the Taiwan ACS Full Spectrum Registry and comprised 3164 patients with a definite onset date during the period October 2008 and January 2010 at 39 hospitals. Meteorological conditions and air pollutant concentrations at the 39 locations during the 488-day period were obtained. Time-lag Poisson and logistic regression were used to explore their association with ACS incidence. One-day lag atmospheric pressure (AP), humidity, particulate matter (PM2.5, and PM10), and carbon monoxide (CO) all had significant interaction effects with temperature on ACS occurrence. Days on which high temperatures (>26 °C) and low AP (<1009 hPa) occurred the previous day were associated with a greater likelihood of increased incidence of developing ACS. Typhoon Morakot was an example of high temperature with extremely low AP associated with higher ACS incidence than the daily average. Combinations of high concentrations of PM or CO with low temperatures (<21 °C) and high humidity levels with low temperatures were also associated with increased incidence of ACS. Atmospheric pollution and weather factors have synergistic effects on the incidence of ACS.

High voltage AC plasma torches with long electric arcs for plasma-chemical applications

NASA Astrophysics Data System (ADS)

Surov, A. V.; Popov, S. D.; Serba, E. O.; Pavlov, A. V.; Nakonechny, Gh V.; Spodobin, V. A.; Nikonov, A. V.; Subbotin, D. I.; Borovskoy, A. M.

2017-04-01

Powerful AC plasma torches are in demand for a number of advanced plasma chemical applications, they can provide high enthalpy of the working gas. IEE RAS specialists have developed a number of models of stationary thermal plasma torches for continuous operation on air with the power from 5 to 500 kW, and on mixture of H2O, CO2 and CH4 up to 150 kW. AC plasma torches were tested on the pilot plasmachemical installations. Powerful AC plasma torch with hollow electrodes and the gas vortex stabilization of arc in cylindrical channels and its operation characteristics are presented. Lifetime of its continuous operation on air is 2000 hours and thermal efficiency is about 92%, the electric arc length between two electrodes of the plasma torch exceeds 2 m.

Air Conditioning Modifications to AMG Buses

DOT National Transportation Integrated Search

1983-12-01

This report presents the documentation and evaluation of air conditioning system modifications devised by Miami (Florida) Metrobus and Los Angeles SCRTD for the AM General Model B bus. The objective of these modifications was to reduce the frequency ...

Thermal Environment for Classrooms. Central System Approach to Air Conditioning.

ERIC Educational Resources Information Center

Triechler, Walter W.

This speech compares the air conditioning requirements of high-rise office buildings with those of large centralized school complexes. A description of one particular air conditioning system provides information about the system's arrangement, functions, performance efficiency, and cost effectiveness. (MLF)

Investigation of the AC Plasma Torch Working Conditions for the Plasma Chemical Applications

NASA Astrophysics Data System (ADS)

Safronov, A. A.; Vasilieva, O. B.; Dudnik, J. D.; E Kuznetsov, V.; Shiryaev, V. N.; Subbotin, D. I.; Pavlov, A. V.

2017-04-01

The presented design and parameters of a three-phase AC plasma torch with the power up to 500 kW, flow rate of air 30-50 g/s (temperature up to 5000 K) could be used in different plasma chemical processes. Range of measured plasma temperature is 3500-5000 K. The paper presents investigations of the plasma torch operation modes for its application in plasma chemical technologies. Plasma chemical technologies for various purposes (processing, destruction of various wastes, including technological and hazardous waste, conversion or production of chemicals to obtain nanoscale materials, etc.) are very promising in terms of the process efficiency. Their industrial use is difficult due to the lack of inexpensive and reliable plasma torches providing the desired level of temperature, enthalpy of the working gas and other necessary conditions for the process. This problem can be solved using a considered design of a three-phase alternating current plasma torch with power of 150-500 kW with working gas flow rate of 30-50 g/s with mass average temperature up to 5000K on the basis of which an industrial plasma chemical plant can be created. The basis of the plasma torch operation is a railgun effect that is the principle of arc movement in the field of its own current field. Thanks to single supply of power to the arc, arcs forming in the discharge chamber of the plasma torch move along the electrodes under the action of electrodynamic forces resulting from the interaction of the arc current with its own magnetic field. Under the condition of the three-phase supply voltage, arc transits from the electrode to the electrode with change in the anodic and cathodic phases with frequency of 300 Hz. A special feature of this design is the ability to organize the movement of the arc attachment along the electrode, thus ensuring an even distribution of the thermal load and thus achieve long time of continuous operation of the plasma torch. The parameters of the plasma jet of the

Possible Economies in Air-Conditioning by Accepting Temperature Swings.

ERIC Educational Resources Information Center

Loudon, A. G.; Petherbridge, P.

Public building air conditioning systems, which use constant and varying heat and cooling loads, are compared and investigated. Experiments indicated that constant temperature controls based on outside air temperature alone were inefficient. Ventilating a building with outside air and the methods of doing so are cited as being the most economical…

Effects of Air Conditioner Use on Real-World Fuel Economy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huff, Shean P; West, Brian H; Thomas, John F

2013-01-01

Vehicle data were acquired on-road and on a chassis dynamometer to assess fuel consumption under several steady cruise conditions and at idle. Data were gathered for various air conditioner (A/C) settings and with the A/C off and the windows open. Two vehicles were used in the comparisonstudy: a 2009 Ford Explorer and a 2009 Toyota Corolla. At steady speeds between 64.4 and 112.7 kph (40 and 70 mph), both vehicles consumed more fuel with the A/C on at maximum cooling load (compressor at 100% duty cycle) than when driving with the windows down. The Explorer maintained this trend beyond 112.7more » kph (70 mph), while the Corolla fuel consumption with the windows down matched that of running the A/C at 120.7 kph (75 mph), and exceeded it at 128.7 kph (80 mph). The largest incremental fuel consumption rate penalty due to air conditioner use occurred was nearly constant with a weakslight trend of increasing consumption with increasing compressor (and vehicle) speed. Lower consumption is seenobserved at idle for both vehicles, likely due to the low compressor speed at this operating point« less

Comparison of Descemet stripping under continuous air flow, manual air injection and balanced salt solution for DMEK: a pilot study.

PubMed

Gabbay, I E; Bahar, I; Nahum, Y; Livny, E

2017-08-01

Descemet's membrane endothelial keratoplasty (DMEK) involves removal of the recipient's Descemet membrane (DM) prior to transplanting the donor's DM. When using balanced salt solution (BSS) or ophthalmic viscosurgical devices (OVDs), visualization of the host's DM during its stripping may be inadequate and may result in Descemet remnants and could lead to sub-optimal surgical results. Previous articles described excellent visualization when utilizing air injection but this requires repeated air injection into the anterior chamber (AC). We present a pilot study that compares different techniques under which DM stripping can be performed: with continuous automated air infusion, with manual air infusion, and with BSS. We retrospectively compared video footage of DM stripping with BSS, with continuous air and with manual injection of air into the AC to determine DM stripping duration and the number of times the surgeon had to insert and retrieve a surgical instrument from the AC. Thirty videos of 10 consecutive cases of the three DM stripping techniques were evaluated. DM stripping duration was 3.26 (±1.32), 3.92 (±1.2) and 12.9 (±3.98) minutes for BSS, continuous air flow, and manual air injection, respectively. Frequency of instrument retrieval (FIR) was 3.6 (±1.71), 1.5 (±0.71) and 15.1 (±3.28) for BSS, continuous air flow, and manual air injection, respectively. Continuous air flow and BSS were both statistically different than manual air injection into the AC (p < 0.05), but did not differ from one another statistically. DM stripping during posterior lamellar surgery is imperative for favorable post-operative results and prevention of complications. Performing this step under air in the AC contributes to better visualization and an efficient surgery.

Uncertainty Evaluation of Residential Central Air-conditioning Test System

NASA Astrophysics Data System (ADS)

Li, Haoxue

2018-04-01

According to national standards, property tests of air-conditioning are required. However, test results could be influenced by the precision of apparatus or measure errors. Therefore, uncertainty evaluation of property tests should be conducted. In this paper, the uncertainties are calculated on the property tests of Xinfei13.6 kW residential central air-conditioning. The evaluation result shows that the property tests are credible.

The influence of air-conditioning on street temperatures in the city of Paris

NASA Astrophysics Data System (ADS)

de Munck, C. S.; Pigeon, G.; Masson, V.; Marchadier, C.; Meunier, F.; Tréméac, B.; Merchat, M.

2010-12-01

A consequence of urban heat islands in summer is the increased use of air-conditioning during extreme heat events : the use of air-conditioning systems, while cooling the inside of buildings releases waste heat (as latent and sensible heat) in the lower part of the urban atmosphere, hence potentially increasing air street temperatures where the heat is released. This may lead locally to a further increase in air street temperatures, therefore increasing the air cooling demand, while at the same time lowering the efficiency of air-conditioning units. A coupled model consisting of a meso-scale meteorological model (MESO-NH) and an urban energy balance model (TEB) has been implemented with an air-conditioning module and used in combination to real spatialised datasets to understand and quantify potential increases in temperature due to air-conditioning heat releases for the city of Paris . In a first instance, the current types of air-conditioning systems co-existing in the city were simulated (underground chilled water network, wet cooling towers and individual air-conditioning units) to study the effects of latent and sensible heat releases on street temperatures. In a third instance, 2 scenarios were tested to characterise the impacts of likely future trends in air-conditioning equipment in the city : a first scenario for which current heat releases were converted to sensible heat, and a second based on 2030s projections of air-conditioning equipment at the scale of the city. All the scenarios showed an increase in street temperature which, as expected, was greater at night time than day time. For the first two scenarios, this increase in street temperatures was localised at or near the sources of air-conditioner heat releases, while the 2030s air-conditioning scenario impacted wider zones in the city. The amplitude of the increase in temperature varied from 0,25°C to 1°C for the air-conditioning current state, between 0,25°C and 2°C for the sensible heat

Air Conditioning and Refrigeration Supplementary Units.

ERIC Educational Resources Information Center

Winston, Del; And Others

This document contains supplemental materials for special needs high school students intended to facilitate their mainstreaming in regular air conditioning and refrigeration courses. Teacher's materials precede the materials for students and include general notes for the instructor, additional suggestions, two references, a questionnaire on the…

[Assessment of the air quality improment of cleaning and disinfection on central air-conditioning ventilation system].

PubMed

Liu, Hongliang; Zhang, Lei; Feng, Lihong; Wang, Fei; Xue, Zhiming

2009-09-01

To assess the effect of air quality of cleaning and disinfection on central air-conditioning ventilation systems. 102 air-conditioning ventilation systems in 46 public facilities were sampled and investigated based on Hygienic assessment criterion of cleaning and disinfection of public central air-conditioning systems. Median dust volume decreased from 41.8 g/m2 to 0.4 g/m2, and the percentage of pipes meeting the national standard for dust decreased from 17.3% (13/60) to 100% (62/62). In the dust, median aerobic bacterial count decreased from 14 cfu/cm2 to 1 cfu/cm2. Median aerobic fungus count decreased from 10 cfu/cm2 to 0 cfu/cm2. The percentage of pipes with bacterial and fungus counts meeting the national standard increased from 92.4% (171/185) and 82.2% (152/185) to 99.4% (165/166) and 100% (166/166), respectively. In the ventilation air, median aerobic bacterial count decreased from 756 cfu/m3 to 229 cfu/m3. Median aerobic fungus count decreased from 382 cfu/m3 to 120 cfu/m3. The percentage of pipes meeting the national standard for ventilation air increased from 33.3% (81/243) and 62.1% (151/243) to 79.8% (292/366) and 87.7% (242/276), respectively. But PM10 rose from 0.060 mg/m3 to 0.068 mg/m3, and the percentage of pipes meeting the national standard for PM10 increased from 74.2% (13/60) to 90.2% (46/51). The cleaning and disinfection of central air-conditioning ventilation systems could have a beneficial effect of air quality.

Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons.

PubMed

Lv, Jinze; Zhu, Lizhong

2013-03-01

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without air conditioning (AC-off period), concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor air and outdoor air (r(p) > 0.769, p < 0.05), and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs. During the period when the central ventilation and air conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the concentrations and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket.

Allergies to molds caused by fungal spores in air conditioning equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schata, M.; Jorde, W.; Elixmann, J.H.

1989-01-01

People suffering from various symptoms while in air-conditioned rooms often show sensitizations to fungi that can be isolated when the fungi are removed from air conditioners. By using specific challenge tests it was shown that fungal spores in air conditioners can evoke allergic symptoms. Hyposensitization was the specific therapy prescribed for such allergic reactions. After hyposensitization therapy, more than 70% of the patients so treated could live and work again in air-conditioned rooms without developing specific symptoms.

[Biological contamination in office buildings related to ventilation/air conditioning system].

PubMed

Bródka, Karolina; Sowiak, Małgorzata; Kozajda, Anna; Cyprowski, Marcin; Irena, Szadkowska-Stańczyk

2012-01-01

Indoor air is contaminated with microorganisms coming from both the atmospheric air and sources present in premises. The aim of this study was to analyze the concentrations of biological agents in office buildings, dependending on ventilation/air conditioning system and season. The study covered office buildings (different in the system of ventila-tion/air conditioning). Air samples for assessing the levels of inhalable dust, endotoxins and (1-->3)-beta-D-glucans, were taken at the selected stationary points of each building during summer and winter. The air was sampled for 6 h, using portable sets consisting of the GilAir 5 pump and the head filled with a filter of fiber glass. The samples for the presence of airborne bacteria and fungi were collected twice during the day using the impaction method. Average concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans in office premises were 0.09 mg/m3, 6.00 x 10(2) cfu/m3, 4.59 x 10(1) cfu/m3, 0.42 ng/m3 and 3.91 ng/m3, respectively. Higher concentrations of the investigated agents were found in summer. In premises with air conditioning concentrations of airborne fungi, (1-->3)-beta-D-glucans and inhalable dust were significantly lower in winter. In summer the trend was reverse except for (1-->3)-beta-D-glucans. Concentrations of biological agents were affected by the season and the presence of air conditioning. Concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans, observed inside the office buildings, were significantly higher in summer than in winter. The presence of the air conditioning system modified in various ways the levels of biological agents. Its influence was greater on the concentration of fungi and (1-->3)-beta-D-glucans than on that of bacteria and endotoxins.

Ru-Sn/AC for the Aqueous-Phase Reduction of Succinic Acid to 1,4-Butanediol under Continuous Process Conditions

DOE PAGES

Vardon, Derek R.; Settle, Amy E.; Vorotnikov, Vassili; ...

2017-08-18

Succinic acid is a biomass-derived platform chemical that can be catalytically converted in the aqueous phase to 1,4-butanediol (BDO), a prevalent building block used in the polymer and chemical industries. Despite significant interest, limited work has been reported regarding sustained catalyst performance and stability under continuous aqueous-phase process conditions. As such, this work examines Ru-Sn on activated carbon (AC) for the aqueous-phase conversion of succinic acid to BDO under batch and flow reactor conditions. Initially, powder Ru-Sn catalysts were screened to determine the most effective bimetallic ratio and provide a comparison to other monometallic (Pd, Pt, Ru) and bimetallic (Pt-Sn,more » Pd-Re) catalysts. Batch reactor tests determined that a ~1:1 metal weight ratio of Ru to Sn was effective for producing BDO in high yields, with complete conversion resulting in 82% molar yield. Characterization of the fresh Ru-Sn catalyst suggests that the sequential loading method results in Ru sites that are colocated and surface-enriched with Sn. Postbatch reaction characterization confirmed stable Ru-Sn material properties; however, upon a transition to continuous conditions, significant Ru-Sn/AC deactivation occurred due to stainless steel leaching of Ni that resulted in Ru-Sn metal crystallite restructuring to form discrete Ni-Sn sites. Computational modeling confirmed favorable energetics for Ru-Sn segregation and Ni-Sn formation at submonolayer Sn incorporation. To address stainless steel leaching, reactor walls were treated with an inert silica coating by chemical vapor deposition. With leaching reduced, stable Ru-Sn/AC performance was observed that resulted in a molar yield of 71% BDO and 15% tetrahydrofuran for 96 h of time on stream. Postreaction catalyst characterization confirmed low levels of Ni and Cr deposition, although early-stage islanding of Ni-Sn will likely be problematic for industrially relevant time scales (i.e., thousands of hours

The Effect of Air-Conditioning on Student and Teacher Performance.

ERIC Educational Resources Information Center

Phoenix Union High School District, AZ. Dept. of Research and Planning.

The literature is reviewed to see if research shows a relationship between student and teacher performance and air conditioning of classrooms. The benefits of air conditioning in promoting learning are substantiated by studies that are summarized but not cited. The relationship of the report to the Phoenix Union High School System Advisory…

Influence of cooling face masks on nasal air conditioning and nasal geometry.

PubMed

Lindemann, J; Hoffmann, T; Koehl, A; Walz, E M; Sommer, F

2017-06-01

Nasal geometries and temperature of the nasal mucosa are the primary factors affecting nasal air conditioning. Data on intranasal air conditioning after provoking the trigeminal nerve with a cold stimulus simulating the effects of an arctic condition is still missing. The objective was to investigate the influence of skin cooling face masks on nasal air conditioning, mucosal temperature and nasal geometry. Standardized in vivo measurements of intranasal air temperature, humidity and mucosal temperature were performed in 55 healthy subjects at defined detection sites before and after wearing a cooling face mask. Measurements of skin temperature, rhinomanometry and acoustic rhinometry were accomplished. After wearing the face mask the facial skin temperature was significantly reduced. Intranasal air temperature did not change. Absolute humidity and mucosal temperature increased significantly. The acoustic rhinometric results showed a significant increase of the volumes and the cross-sectional areas. There was no change in nasal airflow. Nasal mucosal temperature, humidity of inhaled air, and volume of the anterior nose increased after application of a cold face mask. The response is mediated by the trigeminal nerve. Increased mucosal temperatures as well as changes in nasal geometries seem to guarantee sufficient steady intranasal nasal air conditioning.

Fundamentals of Air Conditioning and Refrigeration.

ERIC Educational Resources Information Center

Clemons, Mark

This set of instructional materials provides secondary and postsecondary students with a state-of-the-art curriculum for the air conditioning and refrigeration industry that includes the many changes brought by new Environmental Protection Agency (EPA) regulations. Introductory materials explain the use of this publication and provide the…

Readings in Air Conditioning and Refrigeration.

ERIC Educational Resources Information Center

Uberto, Jeffrey A.

Designed to encourage vocational high school students to read by offering reading materials relevant to their vocational goals, this document contains thirty-seven articles related to air conditioning and refrigeration which have been selected from trade journals, magazines, and newspapers and adapted to the students' reading capabilities. A…

Automotive Air Conditioning and Heating; Automotive Mechanics (Advanced): 9047.04.

ERIC Educational Resources Information Center

Dade County Public Schools, Miami, FL.

This document presents an outline for a 135-hour course designed to provide the student with all the foundations necessary to become employable in the automotive air conditioning and heating trade. The course of study includes an orientation to the world of work, the elementary physics of air conditioning and heating, and laboratory experiments…

Impact of air conditioning system operation on increasing gases emissions from automobile

NASA Astrophysics Data System (ADS)

Burciu, S. M.; Coman, G.

2016-08-01

The paper presents a study concerning the influence of air conditioning system operation on the increase of gases emissions from cars. The study focuses on urban operating regimes of the automobile, regimes when the engines have low loads or are operating at idling. Are presented graphically the variations of pollution emissions (CO, CO2, HC) depending of engine speed and the load on air conditioning system. Additionally are presented, injection duration, throttle position, the mechanical power required by the compressor of air conditioning system and the refrigerant pressure variation on the discharge path, according to the stage of charging of the air conditioning system.

Air Conditioning and Refrigeration. Book One.

ERIC Educational Resources Information Center

Wantiez, Gary W.

Designed to provide students with the basic skills for an occupation in air conditioning and refrigeration, this curriculum guide includes seven major areas, each consisting of one or more units of instruction. These areas and their respective units are titled as follows: Orientation (history and development, and job opportunities), Safety…

Air Conditioning and Refrigeration Book IV.

ERIC Educational Resources Information Center

Eckes, William; Fulkerson, Dan

This publication is the concluding text in a four-part curriculum for air conditioning and refrigeration. Materials in Book 4 are designed to complement theoretical and functional elements in Books 1-3. Instructional materials in this publication are written in terms of student performance using measurable objectives. The course includes six…

Design and demonstration of a storage-assisted air conditioning system

NASA Astrophysics Data System (ADS)

Rizzuto, J. E.

1981-03-01

The system is a peak-shaving system designed to provide a levelized air conditioning load. The system also requires minimum air conditioner and thermal storage capacity. The storage-assisted air conditioning system uses a Glauber's salt-based phase change material in sausage like containers called CHUBS. The CHUBS are two (2) inches in diameter and 20 inches long. They are stacked in modules of 64 CHUBS which are appropriately spaced and oriented in the storage system so that air may pass perpendicular to the long axis of the CHUBS. The phase change material, has a thermal storage capacity in the range of 45 to 50 Btu/lb and a transition temperature of approximately 55 F.

Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools

EPA Pesticide Factsheets

The main purposes of a Heating, Ventilation, and Air-Conditioning system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

Potential Evaluation of Solar Heat Assisted Desiccant Hybrid Air Conditioning System

NASA Astrophysics Data System (ADS)

Tran, Thien Nha; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

The solar thermal driven desiccant dehumidification-absorption cooling hybrid system has superior advantage in hot-humid climate regions. The reasonable air processing of desiccant hybrid air conditioning system and the utility of clean and free energy make the system environment friendly and energy efficient. The study investigates the performance of the desiccant dehumidification air conditioning systems with solar thermal assistant. The investigation is performed for three cases which are combinations of solar thermal and absorption cooling systems with different heat supply temperature levels. Two solar thermal systems are used in the study: the flat plate collector (FPC) and the vacuum tube with compound parabolic concentrator (CPC). The single-effect and high energy efficient double-, triple-effect LiBr-water absorption cooling cycles are considered for cooling systems. COP of desiccant hybrid air conditioning systems are determined. The evaluation of these systems is subsequently performed. The single effect absorption cooling cycle combined with the flat plate collector solar system is found to be the most energy efficient air conditioning system.

Air Conditioning and Refrigeration Book III.

ERIC Educational Resources Information Center

Eckes, William; Fulkerson, Dan

Designed to present theory as a functional aspect, this air conditioning and refrigeration curriculum guide is comprised of nine units of instruction. Unit titles include (1) Job Orientation, (2) Applying for a Job, (3) Customer Relations, (4) Business Management, (5) Psychometrics, (6) Residential Heat Loss and Heat Gain, (7) Duct Design and…

Data characteristic analysis of air conditioning load based on fast Fourier transform

NASA Astrophysics Data System (ADS)

Li, Min; Zhang, Yanchi; Xie, Da

2018-04-01

With the development of economy and the improvement of people's living standards, air conditioning equipment is more and more popular. The influence of air conditioning load for power grid is becoming more and more serious. In this context it is necessary to study the characteristics of air conditioning load. This paper analyzes the data of air conditioning power consumption in an office building. The data is used for Fast Fourier Transform by data analysis software. Then a series of maps are drawn for the transformed data. The characteristics of each map were analyzed separately. The hidden rules of these data are mined from the angle of frequency domain. And these rules are hard to find in the time domain.

A morphological study of the changes in the ultrastructure of a bacterial biofilm disrupted by an ac corona discharge in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stepanova, Olga, E-mail: o.m.stepanova@spbu.ru; Astafiev, Alexander; Kudryavtsev, Anatoly

The morphology of bacterial cells and biofilms subjected to a low frequency (∼10{sup 5} Hz) ac (∼10{sup −1} A) corona discharge was investigated using electron microscopy. A low-frequency ac corona discharge in air is shown to have a bactericidal and bacteriostatic effect on Escherichia coli M17 culture at both the cellular and population levels. Corona exposure inhibits the formation of a microbial community and results in the destruction of formed biofilms. This paper presents data on changes in the ultrastructure of cells and biofilms after corona treatment. Our results suggest that the E. coli M17 cells inside biofilms are affectedmore » with results similar to sub-lethal and lethal thermal exposure. Some of the biological aspects of colony and biofilm cells death are evaluated. Morphological changes in the ultrastructure of the biofilms under corona treatment are described. Our results indicate that the heating effect is the main factor responsible for the corona-induced inactivation of bacteria.« less

Antennas Designed for Advanced Communications for Air Traffic Management (AC/ATM) Project

NASA Technical Reports Server (NTRS)

Zakrajsek, Robert J.

2000-01-01

The goal of the Advanced Communications for Air Traffic Management (AC/ATM) Project at the NASA Glenn Research Center at Lewis Field is to enable a communications infrastructure that provides the capacity, efficiency, and flexibility necessary to realize a mature free-flight environment. The technical thrust of the AC/ATM Project is targeted at the design, development, integration, test, and demonstration of enabling technologies for global broadband aeronautical communications. Since Ku-band facilities and equipment are readily available, one of the near-term demonstrations involves a link through a Kuband communications satellite. Two conformally mounted antennas will support the initial AC/ATM communications links. Both of these are steered electronically through monolithic microwave integrated circuit (MMIC) amplifiers and phase shifters. This link will be asymmetrical with the downlink to the aircraft (mobile vehicle) at a throughput rate of greater than 1.5 megabits per second (Mbps), whereas the throughput rate of the uplink from the aircraft will be greater than 100 kilobits per second (kbps). The data on the downlink can be narrow-band, wide-band, or a combination of both, depending on the requirements of the experiment. The AC/ATM project is purchasing a phased-array Ku-band transmitting antenna for the uplink from the test vehicle. Many Ku-band receiving antennas have been built, and one will be borrowed for a short time to perform the initial experiments at the NASA Glenn Research Center at Lewis Field. The Ku-band transmitting antenna is a 254-element MMIC phased-array antenna being built by Boeing Phantom Works. Each element can radiate 100 mW. The antenna is approximately 43-cm high by 24-cm wide by 3.3-cm thick. It can be steered beyond 60 from broadside. The beamwidth varies from 6 at broadside to 12 degrees at 60 degrees, which is typical of phased-array antennas. When the antenna is steered to 60 degrees, the beamwidth will illuminate

Air Conditioning and Refrigeration. Book Two.

ERIC Educational Resources Information Center

Wantiez, Gary W.

This curriculum guide (book II), along with book I, is designed to provide students with the basic skills for an occupation in air conditioning and refrigeration. Six major areas are included, each consisting of one or more units of instruction. These areas and their respective units are titled as follows: Electricity (fundamentals of electricity,…

14 CFR 203.5 - Compliance as condition on operations in air transportation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... air transportation. 203.5 Section 203.5 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... DEFENSES § 203.5 Compliance as condition on operations in air transportation. It shall be a condition on the authority of all direct U.S. and foreign carriers to operate in air transportation that they have...

Transcranial Alternating Current Stimulation (tACS) Mechanisms and Protocols

PubMed Central

Tavakoli, Amir V.; Yun, Kyongsik

2017-01-01

Perception, cognition and consciousness can be modulated as a function of oscillating neural activity, while ongoing neuronal dynamics are influenced by synaptic activity and membrane potential. Consequently, transcranial alternating current stimulation (tACS) may be used for neurological intervention. The advantageous features of tACS include the biphasic and sinusoidal tACS currents, the ability to entrain large neuronal populations, and subtle control over somatic effects. Through neuromodulation of phasic, neural activity, tACS is a powerful tool to investigate the neural correlates of cognition. The rapid development in this area requires clarity about best practices. Here we briefly introduce tACS and review the most compelling findings in the literature to provide a starting point for using tACS. We suggest that tACS protocols be based on functional brain mechanisms and appropriate control experiments, including active sham and condition blinding. PMID:28928634

Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

PubMed

Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

2008-07-01

Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

Self-assembly of short amyloidogenic peptides at the air-water interface.

PubMed

Chaudhary, Nitin; Nagaraj, Ramakrishnan

2011-08-01

Short peptide stretches in amyloidogenic proteins can form amyloid fibrils in vitro and have served as good models for studying amyloid fibril formation. Recently, these amyloidogenic peptides have gained considerable attention, as non-amyloid ordered structures can be obtained from these peptides by carefully tuning the conditions of self-assembly, especially pH, temperature and presence of organic solvents. We have examined the effect of surface pressure on the self-assembled structures of two amyloidogenic peptides, Pβ(2)m (Ac-DWSFYLLYYTEFT-am) and AcPHF6 (Ac-VQIVYK-am) at the air-water interface when deposited from different solvents. Both the peptides are surface-active and form Thioflavin T (ThT) positive structures at the air-water interface. There is considerable hysteresis in the compression and expansion isotherms, suggesting the occurrence of structural rearrangements during compression. Preformed Pβ(2)m fibrillar structures at the air-water interface are disrupted as peptide is compressed to lower molecular areas but restored if the film is expanded, suggesting that the process is reversible. AcPHF6, on the other hand, shows largely sheet-like structures at lower molecular areas. The solvents used for dissolution of the peptides appear to influence the nature of the aggregates formed. Our results show that like hydrostatic pressure, surface pressure can also be utilized for modulating the self-assembly of the amyloidogenic and self-assembling peptides. Copyright © 2011 Elsevier Inc. All rights reserved.

Criterion-Referenced Test (CRT) Items for Air Conditioning, Heating and Refrigeration.

ERIC Educational Resources Information Center

Davis, Diane, Ed.

These criterion-referenced test (CRT) items for air conditioning, heating, and refrigeration are keyed to the Missouri Air Conditioning, Heating, and Refrigeration Competency Profile. The items are designed to work with both the Vocational Instructional Management System and Vocational Administrative Management System. For word processing and…

Enabling Smart Air Conditioning by Sensor Development: A Review

PubMed Central

Cheng, Chin-Chi; Lee, Dasheng

2016-01-01

The study investigates the development of sensors, in particular the use of thermo-fluidic sensors and occupancy detectors, to achieve smart operation of air conditioning systems. Smart operation refers to the operation of air conditioners by the reinforcement of interaction to achieve both thermal comfort and energy efficiency. Sensors related to thermal comfort include those of temperature, humidity, and pressure and wind velocity anemometers. Improvements in their performance in the past years have been studied by a literature survey. Traditional occupancy detection using passive infra-red (PIR) sensors and novel methodologies using smartphones and wearable sensors are both discussed. Referring to the case studies summarized in this study, air conditioning energy savings are evaluated quantitatively. Results show that energy savings of air conditioners before 2000 was 11%, and 30% after 2000 by the integration of thermo-fluidic sensors and occupancy detectors. By utilizing wearable sensing to detect the human motions, metabolic rates and related information, the energy savings can reach up to 46.3% and keep the minimum change of predicted mean vote (∆PMV→0), which means there is no compromise in thermal comfort. This enables smart air conditioning to compensate for the large variations from person to person in terms of physiological and psychological satisfaction, and find an optimal temperature for everyone in a given space. However, this tendency should be evidenced by more experimental results in the future. PMID:27916906

Design of a solar energy assisted air conditioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varlet, J.L.P.; Johnson, B.R.; Vora, J.N.

1976-03-24

Energy consumption in air conditioning systems can be reduced by reducing the water content of air before cooling. This reduction in humidity can be accomplished by contacting the humid air with a hygroscopic solution in a spray tower. The hydroscopic solution, diluted by water from the air, can be reconcentrated in a solar evaporator. A solar evaporator for this purpose was evaluated by formulating simultaneous energy and mass balances for forced air convection through the evaporator. Temperatures in the evaporator were calculated by numerical integration of the mathematical model. The calculations indicated that the salt solution cannot be reconcentrated inmore » a forced convection evaporator because of the large energy losses associated with the air stream passing through the evaporator.« less

Repair Air Conditioning, COC Bldg 2605, First Floor Plan. By ...

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

Repair Air Conditioning, COC Bldg 2605, First Floor Plan. By Strategic Air Command, Civil Engineering. Drawing no. R-156, sheet no. 2 of 4, 15 August 1968; project no. MAR-125-8;CE-572; file drawer 2605-6. Scale one-eighth inch to one foot. 29x41 inches. pencil on paper 405 - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

40 CFR 86.162-03 - Approval of alternative air conditioning test simulations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... conditioning test simulations. 86.162-03 Section 86.162-03 Protection of Environment ENVIRONMENTAL PROTECTION... alternative air conditioning test simulations. (a) Upon petition from a manufacturer or upon the Agency's own initiative, the Administrator will approve a simulation of the environmental cell for air conditioning test...

40 CFR 86.162-03 - Approval of alternative air conditioning test simulations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... conditioning test simulations. 86.162-03 Section 86.162-03 Protection of Environment ENVIRONMENTAL PROTECTION... alternative air conditioning test simulations. (a) Upon petition from a manufacturer or upon the Agency's own initiative, the Administrator will approve a simulation of the environmental cell for air conditioning test...

40 CFR 86.162-03 - Approval of alternative air conditioning test simulations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... conditioning test simulations. 86.162-03 Section 86.162-03 Protection of Environment ENVIRONMENTAL PROTECTION... alternative air conditioning test simulations. (a) Upon petition from a manufacturer or upon the Agency's own initiative, the Administrator will approve a simulation of the environmental cell for air conditioning test...

40 CFR 86.162-03 - Approval of alternative air conditioning test simulations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... conditioning test simulations. 86.162-03 Section 86.162-03 Protection of Environment ENVIRONMENTAL PROTECTION... alternative air conditioning test simulations. (a) Upon petition from a manufacturer or upon the Agency's own initiative, the Administrator will approve a simulation of the environmental cell for air conditioning test...

Smart sensors enable smart air conditioning control.

PubMed

Cheng, Chin-Chi; Lee, Dasheng

2014-06-24

In this study, mobile phones, wearable devices, temperature and human motion detectors are integrated as smart sensors for enabling smart air conditioning control. Smart sensors obtain feedback, especially occupants' information, from mobile phones and wearable devices placed on human body. The information can be used to adjust air conditioners in advance according to humans' intentions, in so-called intention causing control. Experimental results show that the indoor temperature can be controlled accurately with errors of less than ±0.1 °C. Rapid cool down can be achieved within 2 min to the optimized indoor capacity after occupants enter a room. It's also noted that within two-hour operation the total compressor output of the smart air conditioner is 48.4% less than that of the one using On-Off control. The smart air conditioner with wearable devices could detect the human temperature and activity during sleep to determine the sleeping state and adjusting the sleeping function flexibly. The sleeping function optimized by the smart air conditioner with wearable devices could reduce the energy consumption up to 46.9% and keep the human health. The presented smart air conditioner could provide a comfortable environment and achieve the goals of energy conservation and environmental protection.

Smart Sensors Enable Smart Air Conditioning Control

PubMed Central

Cheng, Chin-Chi; Lee, Dasheng

2014-01-01

In this study, mobile phones, wearable devices, temperature and human motion detectors are integrated as smart sensors for enabling smart air conditioning control. Smart sensors obtain feedback, especially occupants' information, from mobile phones and wearable devices placed on human body. The information can be used to adjust air conditioners in advance according to humans' intentions, in so-called intention causing control. Experimental results show that the indoor temperature can be controlled accurately with errors of less than ±0.1 °C. Rapid cool down can be achieved within 2 min to the optimized indoor capacity after occupants enter a room. It's also noted that within two-hour operation the total compressor output of the smart air conditioner is 48.4% less than that of the one using On-Off control. The smart air conditioner with wearable devices could detect the human temperature and activity during sleep to determine the sleeping state and adjusting the sleeping function flexibly. The sleeping function optimized by the smart air conditioner with wearable devices could reduce the energy consumption up to 46.9% and keep the human health. The presented smart air conditioner could provide a comfortable environment and achieve the goals of energy conservation and environmental protection. PMID:24961213

The characteristics of welded joints for air conditioning application

NASA Astrophysics Data System (ADS)

Weglowski, M. St.; Weglowska, A.; Miara, D.; Kwiecinski, K.; Błacha, S.; Dworak, J.; Rykala, J.; Pikula, J.; Ziobro, G.; Szafron, A.; Zimierska-Nowak, P.; Richert, M.; Noga, P.

2017-10-01

In the paper the results of metallographic examination of welded joints for air-conditioning elements are presented. The European directives 2006/40/EC on the greenhouse gasses elimination demand to stop using traditional refrigerant and to change it to R744 (CO2) medium in air conditioning installation. The R744 refrigerant is environmental friendly medium if compared with standard solution such as R12, R134a or R1234yf and safer for passengers than R1234yf. The non-standard thermodynamic parameters of the R744 which translate into high pressure and high temperature require specific materials to develop the shape and to specify the technology of manufacturing for the particular elements of the conduits and moreover the technologies of joining for the whole structure, which would meet the exploitation requirements of the new air-conditioning system. To produce the test welded joints of stainless steels four different joining technologies were applied: laser welding, plasma welding, electron beam welding as well as high speed rotation welding. This paper describes the influence of the selected welding process on the macrostructure and microstructure of welded joints of AISI 304 and AISI 316L steels. The results indicated that plasma welding laser welding and electron beam welding technologies guaranty the proper quality of welded joints and can be used for the air conditioning application in automotive industry. However, high speed rotation welding not guarantee the good quality of welded joints and cannot be used for above application.

AC Initiation System.

DTIC Science & Technology

An ac initiation system is described which uses three ac transmission signals interlocked for safety by frequency, phase, and power discrimination...The ac initiation system is pre-armed by the application of two ac signals have the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied. (Author)

Contribution of air conditioning adoption to future energy use under global warming.

PubMed

Davis, Lucas W; Gertler, Paul J

2015-05-12

As household incomes rise around the world and global temperatures go up, the use of air conditioning is poised to increase dramatically. Air conditioning growth is expected to be particularly strong in middle-income countries, but direct empirical evidence is scarce. In this paper we use high-quality microdata from Mexico to describe the relationship between temperature, income, and air conditioning. We describe both how electricity consumption increases with temperature given current levels of air conditioning, and how climate and income drive air conditioning adoption decisions. We then combine these estimates with predicted end-of-century temperature changes to forecast future energy consumption. Under conservative assumptions about household income, our model predicts near-universal saturation of air conditioning in all warm areas within just a few decades. Temperature increases contribute to this surge in adoption, but income growth by itself explains most of the increase. What this will mean for electricity consumption and carbon dioxide emissions depends on the pace of technological change. Continued advances in energy efficiency or the development of new cooling technologies could reduce the energy consumption impacts. Similarly, growth in low-carbon electricity generation could mitigate the increases in carbon dioxide emissions. However, the paper illustrates the enormous potential impacts in this sector, highlighting the importance of future research on adaptation and underscoring the urgent need for global action on climate change.

Contribution of air conditioning adoption to future energy use under global warming

PubMed Central

Davis, Lucas W.; Gertler, Paul J.

2015-01-01

As household incomes rise around the world and global temperatures go up, the use of air conditioning is poised to increase dramatically. Air conditioning growth is expected to be particularly strong in middle-income countries, but direct empirical evidence is scarce. In this paper we use high-quality microdata from Mexico to describe the relationship between temperature, income, and air conditioning. We describe both how electricity consumption increases with temperature given current levels of air conditioning, and how climate and income drive air conditioning adoption decisions. We then combine these estimates with predicted end-of-century temperature changes to forecast future energy consumption. Under conservative assumptions about household income, our model predicts near-universal saturation of air conditioning in all warm areas within just a few decades. Temperature increases contribute to this surge in adoption, but income growth by itself explains most of the increase. What this will mean for electricity consumption and carbon dioxide emissions depends on the pace of technological change. Continued advances in energy efficiency or the development of new cooling technologies could reduce the energy consumption impacts. Similarly, growth in low-carbon electricity generation could mitigate the increases in carbon dioxide emissions. However, the paper illustrates the enormous potential impacts in this sector, highlighting the importance of future research on adaptation and underscoring the urgent need for global action on climate change. PMID:25918391

High Technology Centrifugal Compressor for Commercial Air Conditioning Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruckes, John

2006-04-15

R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration Themore » technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to

NREL Engineers Look for a Cool Way to Make AC Units an Affordable Snap |

Science.gov Websites

installing the components of the EcoSnap-AC. Photo by Dennis Schroeder Engineers Chuck Booten and Jon Winkler Booten drills a hole in the wall to mount the EcoSnap-AC. Photo by Dennis Schroeder The Evolution of an , and eliminating air leaks and water intrusion. Photo by Dennis Schroeder Looking Ahead to a Cooler

Low-Flow Liquid Desiccant Air Conditioning: General Guidance and Site Considerations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozubal, E.; Herrmann, L.; Deru, M.

2014-09-01

Dehumidification or latent cooling in buildings is an area of growing interest that has been identified as needing more research and improved technologies for higher performance. Heating, ventilating, and air-conditioning (HVAC) systems typically expend excessive energy by using overcool-and-reheat strategies to dehumidify buildings. These systems first overcool ventilation air to remove moisture and then reheat the air to meet comfort requirements. Another common strategy incorporates solid desiccant rotors that remove moisture from the air more efficiently; however, these systems increase fan energy consumption because of the high airside pressure drop of solid desiccant rotors and can add heat of absorptionmore » to the ventilation air. Alternatively, liquid desiccant air-conditioning (LDAC) technology provides an innovative dehumidification solution that: (1) eliminates the need for overcooling and reheating from traditional cooling systems; and (2) avoids the increased fan energy and air heating from solid desiccant rotor systems.« less

Sound quality evaluation of air conditioning sound rating metric

NASA Astrophysics Data System (ADS)

Hodgdon, Kathleen K.; Peters, Jonathan A.; Burkhardt, Russell C.; Atchley, Anthony A.; Blood, Ingrid M.

2003-10-01

A product's success can depend on its acoustic signature as much as on the product's performance. The consumer's perception can strongly influence their satisfaction with and confidence in the product. A metric that can rate the content of the spectrum, and predict its consumer preference, is a valuable tool for manufacturers. The current method of assessing acoustic signatures from residential air conditioning units is defined in the Air Conditioning and Refrigeration Institute (ARI 270) 1995 Standard for Sound Rating of Outdoor Unitary Equipment. The ARI 270 metric, and modified versions of that metric, were implemented in software with the flexibility to modify the features applied. Numerous product signatures were analyzed to generate a set of synthesized spectra that targeted spectral configurations that challenged the metric's abilities. A subjective jury evaluation was conducted to establish the consumer preference for those spectra. Statistical correlations were conducted to assess the degree of relationship between the subjective preferences and the various metric calculations. Recommendations were made for modifications to improve the current metric's ability to predict subjective preference. [Research supported by the Air Conditioning and Refrigeration Institute.

Repair Air Conditioning, COC Bldg 2605, Basement Plan. By Strategic ...

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

Repair Air Conditioning, COC Bldg 2605, Basement Plan. By Strategic Air Command, Civil Engineering. Drawing no. R-156, sheet no. 1 of 4, 15 August 1968; project no. MAR-125-8;CE-572; file drawer 2605-5. Last revised 31 August 1968?. Scale one-eighth inch and one-quarter inch to one foot. 29x41 inches. pencil on paper - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

Experimental investigation on AC unit integrated with sensible heat storage (SHS)

NASA Astrophysics Data System (ADS)

Aziz, N. A.; Amin, N. A. M.; Majid, M. S. A.; Hussin, A.; Zhubir, S.

2017-10-01

The growth in population and economy has increases the energy demand and raises the concerns over the sustainable energy source. Towards the sustainable development, energy efficiency in buildings has become a prime objective. In this paper, the integration of thermal energy storage was studied. This paper presents an experimental investigation on the performance of an air conditioning unit integrated with sensible heat storage (SHS) system. The results were compared to the conventional AC systems in the terms of average electricity usage, indoor temperature and the relative humidity inside the experimented room (cabin container). Results show that the integration of water tank as an SHS reduces the electricity usage by 5%, while the integration of well-insulated water tank saves up to 8% of the electricity consumption.

Persistence of initial conditions in continental scale air quality simulations

EPA Science Inventory

This study investigates the effect of initial conditions (IC) for pollutant concentrations in the atmosphere and soil on simulated air quality for two continental-scale Community Multiscale Air Quality (CMAQ) model applications. One of these applications was performed for springt...

Measurements of the air conditioning capacity of the nose during normal and pathological conditions and pharmacological influence.

PubMed

Drettner, B; Falck, B; Simon, H

1977-01-01

A simple method is introduced for measuring the air conditioning capacity of the nose. A flow of 8 1/min dry air is introduced by a catheter into the nasopharynx, while 5 1/min is sucked out from the investigated nasal cavity through a psychrometer. The additional 3 1/min passes down into the pharynx, thus reducing the intermingling with expiratory air. By using CO2 as a tracer, this error was found to be maximally 15% and often about 1%. The three different enthalpy factors: increase in enthalpy of dry air, vaporization, and increase in enthalpy of water vapour, were calculated separately and the vaporization was found to be the dominant factor. The calculated total supply of humidity showed that the method presented causes at least a slight stress on the humidifying capacity. Pharmacological studies have shown that subcutaneously injected atropine decreased the total enthalpy and that of water vapour, while nasal administration of oximetazoline also decreased the total enthalpy. Nasal administration of homatropine or pilocarpine had no effect on the air conditioning. In comparison with normal subjects, those with vasomotor rhinitis had an increased enthalpy of the air, while the same enthalpy factor was reduced in cases with atrophic rhinitis. Laryngectomized patients had no significant difference in the air conditioning capacity of the nose in relation to normal subjects, while patients operated with partial maxillectomy had a considerable reduction in vaporization and total enthalpy.

Keeping cool: use of air conditioning by australians with multiple sclerosis.

PubMed

Summers, Michael P; Simmons, Rex D; Verikios, George

2012-01-01

Despite the known difficulties many people with MS have with high ambient temperatures, there are no reported studies of air conditioning use and MS. This study systematically examined air conditioner use by Australians with MS. A short survey was sent to all participants in the Australian MS Longitudinal Study cohort with a response rate of 76% (n = 2,385). Questions included hours of air-conditioner use, areas cooled, type and age of equipment, and the personal effects of overheating. Air conditioners were used by 81.9% of respondents, with an additional 9.6% who could not afford an air conditioner. Regional and seasonal variation in air conditioning use was reported, with a national annual mean of 1,557 hours running time. 90.7% reported negative effects from overheating including increased fatigue, an increase in other MS symptoms, reduced household and social activities, and reduced work capacity. Households that include people with MS spend between 4 and 12 times more on keeping cool than average Australian households.

Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

PubMed

Möritz, M; Peters, H; Nipko, B; Rüden, H

2001-07-01

The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry (< 80% R. H.) and warm (> 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

Air ion mobility spectra and concentrations upwind and downwind of overhead AC high voltage power lines

NASA Astrophysics Data System (ADS)

Wright, Matthew D.; Buckley, Alison J.; Matthews, James C.; Shallcross, Dudley E.; Henshaw, Denis L.

2014-10-01

Corona ions produced by high-voltage power lines (HVPLs) can alter the nearby electrical environment, potentially increasing aerosol charge levels downwind. However, there is a lack of knowledge concerning the concentration and mobility of ions from AC HVPLs and their dispersion away from the line. We present ion concentration and mobility measurements made near AC HVPLs in South-West England. Examples of typical mobility spectra are shown highlighting features commonly observed. Corona was observed during 33 of 46 measurements, at 9 of 11 sites, with positive or ‘bipolar' (both polarities) ion production commonly seen. Ion production usually increases atmospheric concentrations by only a modest amount, but extreme cases can enhance concentration by an order of magnitude or more. A polarity imbalance is required to increase aerosol charge via ion attachment; this was observed on 15 of 24 days when positive corona was observed, but was not seen for negative ions. Ion mobility was higher downwind compared with upwind for both ion polarities, but the increase was not statistically significant. Future work should focus on identifying and characterising ‘heavy-producing' HVPLs, and obtaining results in conditions which may favour negative ion production e.g. high humidity, inclement weather or during nighttime.

Air conditioning system

DOEpatents

Lowenstein, Andrew; Miller, Jeffrey; Gruendeman, Peter; DaSilva, Michael

2005-02-01

An air conditioner comprises a plurality of plates arranged in a successively stacked configuration with portions thereof having a spaced apart arrangement, and defining between successive adjacent pairs of plates at the spaced apart portions a first and second series of discrete alternating passages wherein a first air stream is passed through the first series of passages and a second air stream is passed through the second series of passages; and said stacked configuration of plates forming integrally therewith a liquid delivery means for delivering from a source a sufficient quantity of a liquid to the inside surfaces of the first series of fluid passages in a manner which provides a continuous flow of the liquid from a first end to a second end of the plurality of plates while in contact with the first air stream.

Standardized Curriculum for Heating and Air Conditioning.

ERIC Educational Resources Information Center

Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

Standardized vocational education course titles and core contents for two courses in Mississippi are provided: heating and air conditioning I and II. The first course contains the following units: (1) orientation; (2) safety; (3) refrigeration gauges and charging cylinder; (4) vacuum pump service operations; (5) locating refrigerant leaks; (6)…

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 6 2012-07-01 2012-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

Discussion on fresh air volume in Temperature and Humidity Independent Control of Air-conditioning System

NASA Astrophysics Data System (ADS)

Cheng, Xiaolong; Liu, Jinxiang; Wang, Yu; Yuan, Xiaolei; Jin, Hui

2018-05-01

The fresh air volume in Temperature and Humidity Independent Control of Air-conditioning System(THIC) of a typical office was comfirmed, under the premise of adopting the refrigeration dehumidifying fresh air unit(7°C/12°C). By detailed calculating the space moisture load and the fresh air volume required for dehumidification in 120 selected major cities in China, it can be inferred that the minimum fresh air volume required for dehumidification in THIC is mainly determined by the local outdoor air moisture and the outdoor wind speed; Then the mathematical fitting software Matlab was used to fit the three parameters, and a simplified formula for calculating the minimum per capita fresh air volume required for dehumidification was obtained; And the indoor relative humidity was simulated by the numerical software Airpak and the results by using the formula data and the data for hygiene were compared to verify the relibility of the simplified formula.

The effect of ventilation strategies of child care centers on indoor air quality and respiratory health of children in Singapore.

PubMed

Zuraimi, M S; Tham, K W; Chew, F T; Ooi, P L

2007-08-01

This paper reports the effects of ventilation strategies on indoor air quality (IAQ) and respiratory health of children within 104 child care centers (CCCs) in a hot and humid climate. The CCCs were categorized by ventilation strategies: natural (NV), air-conditioned and mechanically ventilated (ACMV), air-conditioned using split units (AC), and hybrid (NV and AC operated intermittently). The concentration levels of IAQ parameters in NV CCCs are characterized by the influence of the outdoors and good dilution of indoor pollutants. The lower ventilation rates in air-conditioned CCCs result in higher concentrations of occupant-related pollutants but lower outdoor pollutant ingress. This study also revealed lower prevalence for most asthma and allergy, and respiratory symptoms in children attending NV CCCs. In multivariate analyses controlled for the effects of confounders, the risk of current rhinitis among children is significantly higher if they attend mechanically ventilated CCCs compared to NV CCCs. Air-conditioned CCCs were also associated with higher adjusted prevalence ratio of severe phlegm and cough symptoms and lower respiratory illness. Finally, children attending CCCs with hybrid ventilation are at high risk for almost all the respiratory symptoms studied. This large field study indicates that different ventilation strategies employed by child care centers can cause significant variations in the indoor air quality and prevalence of asthma, allergies and respiratory symptoms of attending children. The higher prevalence rates of allergic and respiratory symptoms among young children, whose immune system is still under-developed, in child care centers, whether fully or partially air-conditioned, suggest that ventilation and plausible growth and propagation mechanisms of allergens and infectious agents be further investigated.

Scanning AC Nanocalorimetry and Its Applications

NASA Astrophysics Data System (ADS)

Xiao, Kechao

This thesis presents an AC nanocalorimetry technique that enables calorimetry measurements on very small quantities of materials over a wide range of scanning rates (from isothermal to 3x10. 3 K/s), temperatures(up to 1200 K), and environments. Such working range bridges the gap between traditional scanning calorimetry of bulk materials and nanocalorimetry. The method relies on a micromachined nanocalorimeter with negligible thermal lags between heater, thermometer, and sample. The ability to perform calorimetry measurements over such a broad range of scanning rates makes it an ideal tool to characterize the kinetics of phase transformations, reactions at elevated temperatures or to explore the behavior of materials far from equilibrium. We demonstrate the technique by performing measurements on thin-film samples of Sn, In, and Bi with thicknesses ranging from 100 to 300 nm. The experimental heat capacities and melting temperatures agree well with literature values. The measured heat capacities are insensitive to the applied AC frequency, scan rate, and heat loss to the environment over a broad range of experimental conditions. The dynamic range of scanning AC nanocalorimetry enables the combination of nanocalorimetry with in-situ x-ray diffraction (XRD) to facilitate interpretation of the calorimetry measurements. Time-resolved XRD during in-situ operation of nanocalorimetry sensors using intense, high-energy synchrotron radiation allows unprecedented characterization of thermal and structural material properties. We demonstrate this experiment with detailed characterization of the melting and solidification of elemental Bi, In and Sn thin-film samples, using heating and cooling rates up to 300 K/s. By combining scanning DC and AC nano-calorimetry techniques, we study the nucleation behavior of undercooled liquid Bi at cooling rates ranging from 10. 1 to 10. 4 K/s. Upon initial melting, the Bi thin-film sample breaksup into isolated islands. The number of islands

Air conditioned suit

NASA Technical Reports Server (NTRS)

Carl, G. R. (Inventor)

1973-01-01

An environmentally controlled suit is described consisting of an airtight outergarment attached by an airtight bellows to the wall of a sterile chamber, an undergarment providing for circulation of air near the skin of the wearer, and a circulation system comprised of air supply and distribution to the extremities of the undegarment and central collection and exhaust of air from the midsection of the undergarment. A workman wearing the undergarment and attached circulation system enters the outer garment through a tunnel in the chamber wall and the attached bellows to work in the chamber without any danger of spreading bacteria.

Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

NASA Astrophysics Data System (ADS)

Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro

2014-12-01

Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.

Keeping Cool: Use of Air Conditioning by Australians with Multiple Sclerosis

PubMed Central

Summers, Michael P.; Simmons, Rex D.; Verikios, George

2012-01-01

Despite the known difficulties many people with MS have with high ambient temperatures, there are no reported studies of air conditioning use and MS. This study systematically examined air conditioner use by Australians with MS. A short survey was sent to all participants in the Australian MS Longitudinal Study cohort with a response rate of 76% (n = 2,385). Questions included hours of air-conditioner use, areas cooled, type and age of equipment, and the personal effects of overheating. Air conditioners were used by 81.9% of respondents, with an additional 9.6% who could not afford an air conditioner. Regional and seasonal variation in air conditioning use was reported, with a national annual mean of 1,557 hours running time. 90.7% reported negative effects from overheating including increased fatigue, an increase in other MS symptoms, reduced household and social activities, and reduced work capacity. Households that include people with MS spend between 4 and 12 times more on keeping cool than average Australian households. PMID:22548176

Neurology cases evaluated by the U.S. Air Force School of Aerospace Medicine 2000-2012.

PubMed

Hesselbrock, Roger; Heaton, John

2014-05-01

Historically, neurologic conditions are a major cause for removing aviators from flying status. Early neuropsychiatry studies included psychiatric conditions along with neurologic disorders. Previously reported data specifically addressing neurologic conditions in aviators are limited. And there is little current neurology-specific data reported. A retrospective review was done on patients with diagnoses evaluated by Neurology at the U.S. Air Force School of Aerospace Medicine Aeromedical Consultation Service (ACS) between 2000 and 2012 using ACS records and databases to identify cases. Patient demographics, major diagnoses with associated International Classification of Diseases (9th rev.) codes, and aeromedical disposition recommendations were abstracted into a separate database for analysis. In total, 871 cases were identified. Patients were predominantly male (91%) with average age 34 and were predominantly pilots (69%). The top neurology-related diagnoses found in our series were headaches, head injuries, and radiculopathies. Of the cases evaluated, 570 aviators (65%) were recommended by ACS to return to flying status. Waiver authorities accepted 88% of ACS recommendations. Current patterns in neurologic conditions in the selected population of cases evaluated by the ACS were presented. Of the neurologic diagnoses seen, a novel finding was the prominence of head injuries in our series not seen in previous studies. This may be due to more stringent aeromedical standards with advances in medical practice and underscores that this issue is not just about disability but affects aircrew operational readiness. Most cases of neurologic disease evaluated by the ACS were recommended for return to flying status.

Microbial Risk Assessment of Air Conditioning Condensate Reuse

EPA Science Inventory

Air conditioning condensate can provide a substantial water source for building-scale collection and non-potable use. Although produced water is anticipated to be of generally high quality, the potential for microbial contamination by biofilm-associated opportunistic pathogens t...

Air Conditioning. Trade and Industrial Education Trade Preparatory Training Guide.

ERIC Educational Resources Information Center

Nebraska State Dept. of Education, Lincoln. Div. of Vocational Education.

One of a series of curriculum guides prepared for the building occupations cluster of the construction/fabrication occupational group, this guide identifies the essentials of the air conditioning trade as recommended by the successful air conditioner. An instructional program based upon the implementation of the guide is expected to prepare a…

Mechanical model for simulating the conditioning of air in the respiratory tract.

PubMed

Bergonse Neto, Nelson; Von Bahten, Luiz Carlos; Moura, Luís Mauro; Coelho, Marlos de Souza; Stori Junior, Wilson de Souza; Bergonse, Gilberto da Fontoura Rey

2007-01-01

To create a mechanical model that could be regulated to simulate the conditioning of inspired and expired air with the same normal values of temperature, pressure, and relative humidity as those of the respiratory system of a healthy young man on mechanical ventilation. Using several types of materials, a mechanical device was built and regulated using normal values of vital capacity, tidal volume, maximal inspiratory pressure, positive end-expiratory pressure, and gas temperature in the system. The device was submitted to mechanical ventilation for a period of 29.8 min. The changes in the temperature of the air circulating in the system were recorded every two seconds. The statistical analysis of the data collected revealed that the device was approximately as efficient in the conditioning of air as is the respiratory system of a human being. By the study endpoint, we had developed a mechanical device capable of simulating the conditioning of air in the respiratory tract. The device mimics the conditions of temperature, pressure, and relative humidity seen in the respiratory system of healthy individuals.

Thermal storage HVAC system retrofit provides economical air conditioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, S.F.

1993-03-01

This article describes an EMS-controlled HVAC system that meets the ventilation and cooling needs of an 18,000-seat indoor ice hockey arena. The Buffalo Memorial Auditorium (affectionately referred to as the Aud) was built in 1937 under the Works Project Administration of the federal government. Its original configuration included a 12,000-seat arena with an ice skating rink. By the late 1980s, the city was unsuccessfully attempting to attract events and tenants to the auditorium, which lacked air conditioning and other modern amenities. Thus, it was decided to renovate the facility to make it marketable. The first phase of the renovation includedmore » installing an air-conditioning system in the arena and repairing the existing building systems that were inoperable because of deferred maintenance. After considering the existing conditions (such as size of the space, intermittent usage, construction restrictions, operating budgets and the limited operations staff), the engineering team designed an innovative HVAC system. The system's features include: a carbon dioxide monitoring device that controls the intake of outside air; an ice storage system that provides chilled water and shifts electrical demand to off-peak hours; and a design that uses the building mass as a heat sink. A new energy management system (EMS) determines building cooling needs based on the type of event, ambient conditions and projected audience size. Then, it selects the most economical method to obtain the desired arena temperature.« less

Innovative Air Conditioning and Climate Control

NASA Technical Reports Server (NTRS)

Graf, John

2015-01-01

NASA needed to develop a desiccant wheel based humidity removal system to enable the long term testing of the Orion CO2 scrubber on the International Space Station. In the course of developing that system, we learned three things that are relevant to energy efficient air conditioning of office towers. NASA developed a conceptual design for a humidity removal system for an office tower environment. We are looking for interested partners to prototype and field test this concept.

Design and demonstration of a storage assisted air conditioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-04-01

One phase-change material, sodium sulfate decahydrate, has generated considerable interest for thermal storage. A form of this material containing salts to adjust the transition point to approximately 55/sup 0/F and a gelling agent to prevent segregation of the salts has been developed. This material is packaged in the form of a CHUB, (a cylinder two inches in diameter and twenty inches long) having a weight of 3.25 pounds and a thermal storage capability of 50 Btu per pound. Under this project, a storage-assisted (partial storage) air conditioning system was designed, installed, monitored and evaluated in a typical residential application. Thismore » feasibility demonstration was conducted under the direction of the Long Island Lighting Company in a single family residence in Melville, Long Island, New York. The demonstration system consisted of a CHUB thermal storage system utilized in conjunction with a one and one-half ton air conditioning unit to cool a house that would normally require a two and one half ton air conditioning unit.« less

Water treatment by the AC gliding arc air plasma

NASA Astrophysics Data System (ADS)

Gharagozalian, Mehrnaz; Dorranian, Davoud; Ghoranneviss, Mahmood

2017-09-01

In this study, the effects of gliding arc (G Arc) plasma system on the treatment of water have been investigated experimentally. An AC power supply of 15 kV potential difference at 50 Hz frequency was employed to generate plasma. Plasma density and temperature were measured using spectroscopic method. The water was contaminated with staphylococcus aureus (Gram-positive) and salmonella bacteria (Gram-negative), and Penicillium (mold fungus) individually. pH, hydrogen peroxide, and nitride contents of treated water were measured after plasma treatment. Decontamination of treated water was determined using colony counting method. Results indicate that G Arc plasma is a powerful and green tool to decontaminate water without producing any byproducts.

Physiological and subjective responses in the elderly when using floor heating and air conditioning systems.

PubMed

Hashiguchi, Nobuko; Tochihara, Yutaka; Ohnaka, Tadakatsu; Tsuchida, Chiaki; Otsuki, Tamio

2004-11-01

The purpose of this study was to investigate the effects of a floor heating and air conditioning system on thermal responses of the elderly. Eight elderly men and eight university students sat for 90 minutes in a chair under the following 3 conditions: air conditioning system (A), floor heating system (F) and no heating system (C). The air temperature of sitting head height for condition A was 25 degrees C, and the maximum difference in vertical air temperature was 4 degrees C. The air and floor temperature for condition F were 21 and 29 degrees C, respectively. The air temperature for condition C was 15 degrees C. There were no significant differences in rectal temperature and mean skin temperature between condition A and F. Systolic blood pressure of the elderly men in condition C significantly increased compared to those in condition A and F. No significant differences in systolic blood pressure between condition A and F were found. The percentage of subjects who felt comfortable under condition F was higher than that of those under condition A in both age groups, though the differences between condition F and A was not significant. Relationships between thermal comfort and peripheral (e.g., instep, calf, hand) skin temperature, and the relationship between thermal comfort and leg thermal sensation were significant for both age groups. However, the back and chest skin temperature and back thermal sensation for the elderly, in contrast to that for the young, was not significantly related to thermal comfort. These findings suggested that thermal responses and physiological strain using the floor heating system did not significantly differ from that using the air conditioning system, regardless of the subject age and despite the fact that the air temperature with the floor heating system was lower. An increase in BP for elderly was observed under the condition in which the air temperature was 15 degrees C, and it was suggested that it was necessary for the elderly

AC-130 Employment

DTIC Science & Technology

2006-01-01

1 AC -130 Employment Subject Area Aviation EWS 2006 Author Captain Robert Hornick, USMC Report Documentation Page Form ApprovedOMB No. 0704...00-2006 4. TITLE AND SUBTITLE AC -130 Employment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER... AC -130 gunship is an aircraft that can provide all of these needs. Regrettably, there are too few AC -130’s in the inventory to cover all the needs

Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons.

PubMed

Quesada-Peñate, I; Julcour-Lebigue, C; Jáuregui-Haza, U J; Wilhelm, A M; Delmas, H

2012-06-30

The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties. Copyright © 2012 Elsevier B.V. All rights reserved.

Ac electroosmotic flows above coplanar electrodes

NASA Astrophysics Data System (ADS)

Kweon Suh, Yong

2009-03-01

Interactive numerical method has been proposed to calculate the ac electroosmotic flows above a pair of coplanar electrodes. The thin electrical triple layer (ETL) has been modeled by an asymptotic theory developed by the authors. The model corresponds to a simple dynamic equation for the surface charge density representing the integrated charge over the inner layer. Interactive calculation of the dynamic equation and the Laplace equation for several periods of ac frequency then yielded steady-state distribution of potential and the potential drop across the Stern and inner layers. The Smoluchowski's slip velocity was then determined from those two set of data and used as the boundary condition for the calculation of the Stokes' flow above the electrodes. We have shown that our solutions compared well with the experimental data reported in the literature. We investigated the effect of various parameters on the slip velocity distribution, such as the ac frequency, the electrode length, the effective Stern-layer thickness and the adsorption coefficients.

Leaf Morphology and Ultrastructure Responses to Elevated O3 in Transgenic Bt (cry1Ab/cry1Ac) Rice and Conventional Rice under Fully Open-Air Field Conditions

PubMed Central

Li, Chunyan; Liu, Biao; Li, Chunhua; Zeng, Qing; Hao, Mingzhuo; Han, Zhengmin; Zhu, Jianguo; Li, Xiaogang; Shen, Wenjing

2013-01-01

Background Elevated tropospheric ozone severely affects not only yield but also the morphology, structure and physiological functions of plants. Because of concerns regarding the potential environmental risk of transgenic crops, it is important to monitor changes in transgenic insect-resistant rice under the projected high tropospheric ozone before its commercial release. Methodology/Principal Findings Using a free-air concentration enrichment (FACE) system, we investigated the changes in leaf morphology and leaf ultrastructure of two rice varieties grown in plastic pots, transgenic Bt Shanyou 63 (Bt-SY63, carrying a fusion gene of cry1Ab and cry1Ac) and its non-transgenic counterpart (SY63), in elevated O3 (E-O3) versus ambient O3 (A-O3) after 64-DAS (Days after seeding), 85-DAS and 102-DAS. Our results indicated that E-O3 had no significant effects on leaf length, leaf width, leaf area, stomatal length and stomatal density for both Bt-SY63 and SY63. E-O3 increased the leaf thickness of Bt-SY63, but decreased that of SY63. O3 stress caused early swelling of the thylakoids of chloroplasts, a significant increase in the proportion of total plastoglobule area in the entire cell area (PCAP) and a significant decrease in the proportion of total starch grain area in the entire cell area (SCAP), suggesting that E-O3 accelerated the leaf senescence of the two rice genotypes. Compared with SY63, E-O3 caused early swelling of the thylakoids of chloroplasts and more substantial breakdown of chloroplasts in Bt-SY63. Conclusions/Significance Our results suggest that the incorporation of cry1Ab/Ac into SY63 could induce unintentional changes in some parts of plant morphology and that O3 stress results in greater leaf damage to Bt-SY63 than to SY63, with the former coupled with higher O3 sensitivity in CCAP (the proportions of total chloroplast area in the entire cell area), PCAP and SCAP. This study provides valuable baseline information for the prospective commercial release

Electrical Characteristics, Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

NASA Astrophysics Data System (ADS)

Chen, Qi; Yan, Limin; Zhang, Hao; Li, Guoxiu

2016-05-01

Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V, 0-500 Hz) and DC (0-3300 V) electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA, the electron density 1015-1016 m-3 and further the power dissipation ≤ 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10-4-10-3 Ω-1·m-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length (31-98 μm) and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process. supported by National Natural Science Foundation of China (No. 51376021), and the Fundamental Research Fund for Major Universities (No. 2013JBM079)

Geothermal as a heat sink application for raising air conditioning efficency

NASA Astrophysics Data System (ADS)

Ibrahim, Hesham Safwat Osman Mohamed

2016-04-01

Objective: Geothermal applications in heating, ventilation, air-conditioning is a US technology for more than 30 years old ,which saves more than 30% average energy cost than the traditional air-conditioning systems systems. Applying this technology in Middle East and African countries would be very feasible specially in Egypt specially as it suffers Electric crisis --The temperature of the condensers and the heat rejecting equipment is much higher than the Egyptian land at different depth which is a great advantages, and must be measured, recorded, and studied accurately -The Far goal of the proposal is to construct from soil analysis a temperature gradient map for Egypt and , African countries on different depth till 100 m which is still unclear nowadays and must be measured and recorded in databases through researches - The main model of the research is to study the heat transfer gradient through the ground earth borehole,grout,high density polyethylene pipes , and water inlet temperature which affect the electric efficiency of the ground source heat pump air conditioning unit Impact on the Region: Such research result will contribute widely in Energy saving sector specially the air conditioning sector in Egypt and the African countries which consumes more than 30% of the electric consumption of the total consumption . and encouraging Green systems such Geothermal to be applied

Air-conditioning vs. presence of pathogenic fungi in hospital operating theatre environment.

PubMed

Gniadek, Agnieszka; Macura, Anna B

2011-01-01

Infections related to modern surgical procedures present a difficult problem for contemporary medicine. Infections acquired during surgery represent a risk factor related to therapeutical interventions. Eradication of microorganisms from hospital operating theatre environment may contribute to reduction of infections as the laminar flow air-conditioning considerably reduces the number of microorganisms in the hospital environment. The objective of the study was to evaluate the occurrence of fungi in air-conditioned operating theatre rooms. The study was carried out in one of the hospitals in Krak6w during December 2009. Indoor air samples and imprints from the walls were collected from five operating theatre rooms. A total of fifty indoor air samples were collected with a MAS-100 device, and twenty five imprints from the walls were collected using a Count Tact method. Fungal growth was observed in 48 air samples; the average numbers of fungi were within the range of 5-100 c.f.u. in one cubic metre of the air. Fungi were detected only in four samples of the wall imprints; the number of fungi was 0.01 c.f.u. per one square centimetre of the surface. The mould genus Aspergillus was most frequently isolated, and the species A. fumigatus and A. versicolor were the dominating ones. To ensure microbiological cleanness of hospital operating theatre, the air-conditioning system should be properly maintained. Domination of the Aspergillus fungi in indoor air as well as increase in the number of moulds in the samples taken in evenings (p < 0.05) may suggest that the room decontamination procedures were neglected.

Transitioning to Low-GWP Alternatives in Unitary Air Conditioning

EPA Pesticide Factsheets

This fact sheet provides current information on low-Global Warming Potential (GWP) refrigerant alternatives used in unitary air-conditioning equipment, relevant to the Montreal Protocol on Substances that Deplete the Ozone Layer.

Estimation of thermal sensation during varied air temperature conditions.

PubMed

Katsuura, T; Tabuchi, R; Iwanaga, K; Harada, H; Kikuchi, Y

1998-03-01

Seven male students were exposed to four varied air temperature environments: hot (37 degrees C) to neutral (27 degrees C) (HN), neutral to hot (NH), cool (17 degrees C) to neutral (CN), and neutral to cool (NC). The air temperature was maintained at the first condition for 20 min, then was changed to the second condition after 15 min and was held there for 20 min. Each subject wore a T-shirt, briefs, trunks, and socks. Each sat on a chair and was continuously evaluated for thermal sensation, thermal comfort, and air velocity sensation. Some physiological and thermal parameters were also measured every 5 s during the experiment. The correlation between thermal sensation and skin temperature at 15 sites was found to be poor. The subjects felt much warmer during the rising phase of the air temperature (CN, NH) than during the descending phase (HN, NC) at a given mean skin temperature. However, thermal sensation at the same heat flux or at the same value of the difference between skin and air temperature (delta(Tsk - Ta)) was not so different among the four experimental conditions, and the correlation between thermal sensation and heat flux or delta(Tsk - Ta) was fairly good. The multiple regression equation of the thermal sensation (TS) on 15 sites of skin temperature (Tsk; degrees C) was calculated and the coefficient of determination (R*2) was found to be 0.656. Higher coefficients of determination were found in the equations of thermal sensation for the heat flux (H; kcal.m-2.h-1) at the right and left thighs of the subjects and on delta(Tsk - Ta) (degrees C) at 4 sites. They were as follows: TS = 2.04 - 0.016 Hright - 0.036 Hleft; R*2 = 0.717, TS = 1.649 + 0.013 delta(Tsk - Ta)UpperArm - 0.036 delta(Tsk - Ta)Chest - 0.223 delta(Tsk - Ta)Thigh-0.083 delta(Tsk - Ta)LowerLeg; R*2 = 0.752, respectively.

Modeling air concentration over macro roughness conditions by Artificial Intelligence techniques

NASA Astrophysics Data System (ADS)

Roshni, T.; Pagliara, S.

2018-05-01

Aeration is improved in rivers by the turbulence created in the flow over macro and intermediate roughness conditions. Macro and intermediate roughness flow conditions are generated by flows over block ramps or rock chutes. The measurements are taken in uniform flow region. Efficacy of soft computing methods in modeling hydraulic parameters are not common so far. In this study, modeling efficiencies of MPMR model and FFNN model are found for estimating the air concentration over block ramps under macro roughness conditions. The experimental data are used for training and testing phases. Potential capability of MPMR and FFNN model in estimating air concentration are proved through this study.

Silver zeolite antimicrobial activity in aluminium heating, ventilation and air conditioning system ducts.

PubMed

Rizzetto, R; Mansi, A; Panatto, D; Rizzitelli, E; Tinteri, C; Sasso, T; Gasparini, R; Crovari, P

2008-03-01

Air pollution in confined environments is a serious health problem, in that most people spend long periods indoors (in homes, offices, classrooms etc.). Some people (children, the elderly, heart disease patients, asthmatic or allergic subjects) are at greater risk because of their conditions of frailty. The growing use of air-conditioning systems in many public and private buildings aggravates this health risk, especially when these systems are not correctly installed or regularly serviced. The aim of our study was to verify the capacity of Ag+ ions to stop the growth of bacteria and moulds inside the ducts of Heating, Ventilation and Air Conditioning system ducts (HVAC) systems when these ducts were lined with active Ag+ ions zeolite-coated panels. A Y-shaped HVAC model with two branches was used; one branch was made of traditional galvanized iron, as was the whole system, while the other was lined with active Ag+ zeolite-coated polyurethane panels. During the test, samples of dust present inside both ducts were collected and seeded in liquid and solid media to detect bacteria and moulds. The presence of bacteria was also sought in the air emerging from the outlets of both ducts. Tests made on samples of particulate collected from the two different ducts revealed a lower total bacterial load in the samples collected from the Ag+ zeolite-coated duct than in the samples from the traditional Zn galvanized duct. In addition, the values of bacterial load found in the air emerging from the Ag+ ions zeolite-lined duct were 5 times lower than those found in the air from the traditional galvanized iron duct. The utilization of Ag+ zeolite-coated panels in air-conditioning systems could improve the quality of the emerging air in comparison with traditional installations in galvanized iron. This innovation could prove particularly advantageous in the event of accidents during the installation of air-conditioning systems or of contaminated aerosols coming from outside.

Combustion of Gaseous Fuels with High Temperature Air in Normal- and Micro-gravity Conditions

NASA Technical Reports Server (NTRS)

Wang, Y.; Gupta, A. K.

2001-01-01

The objective of this study is determine the effect of air preheat temperature on flame characteristics in normal and microgravity conditions. We have obtained qualitative (global flame features) and some quantitative information on the features of flames using high temperature combustion air under normal gravity conditions with propane and methane as the fuels. This data will be compared with the data under microgravity conditions. The specific focus under normal gravity conditions has been on determining the global flame features as well as the spatial distribution of OH, CH, and C2 from flames using high temperature combustion air at different equivalence ratio.

GEM-AC, a stratospheric-tropospheric global and regional model for air quality and climate change: evaluation of gas phase properties

NASA Astrophysics Data System (ADS)

Kaminski, J. W.; Semeniuk, K.; McConnell, J. C.; Lupu, A.; Mamun, A.

2012-12-01

The Global Environmental Multiscale model for Air Quality and climate change (GEM-AC) is a global general circulation model based on the GEM model developed by the Meteorological Service of Canada for operational weather forecasting. It can be run with a global uniform (GU) grid or a global variable (GV) grid where the core has uniform grid spacing and the exterior grid expands. With a GV grid high resolution regional runs can be accomplished without a concern for boundary conditions. The work described here uses GEM version 3.3.2. The gas-phase chemistry consists in detailed reactions of Ox, NOx, HOx, CO, CH4, NMVOCs, halocarbons, ClOx and BrO. We have recently added elements of the Global Modal-aerosol eXtension (GMXe) scheme to address aerosol microphysics and gas-aerosol partitioning. The evaluation of the MESSY GMXe aerosol scheme is addressed in another poster. The Canadian aerosol module (CAM) is also available. Tracers are advected using the semi-Lagrangian scheme native to GEM. The vertical transport includes parameterized subgrid scale turbulence and large scale convection. Dry deposition is implemented as a flux boundary condition in the vertical diffusion equation. For climate runs the GHGs CO2, CH4, N2O, CFCs in the radiation scheme are adjusted to the scenario considered. In GV regional mode at high resolutions a lake model, FLAKE is also included. Wet removal comprises both in-cloud and below-cloud scavenging. With the gas phase chemistry the model has been run for a series of ten year time slices on a 3°×3° global grid with 77 hybrid levels from the surface to 0.15 hPa. The tropospheric and stratospheric gas phase results are compared with satellite measurements including, ACE, MIPAS, MOPITT, and OSIRIS. Current evaluations of the ozone field and other stratospheric fields are encouraging and tropospheric lifetimes for CH4 and CH3CCl3 are in reasonable accord with tropospheric models. We will present results for current and future climate

Air Conditioning, Heating, and Refrigeration: Scope and Sequence.

ERIC Educational Resources Information Center

Nashville - Davidson County Metropolitan Public Schools, TN.

This scope and sequence guide, developed for an air conditioning, heating, and refrigeration vocational education program, represents an initial step in the development of a systemwide articulated curriculum sequence for all vocational programs within the Metropolitan Nashville Public School System. It was developed as a result of needs expressed…

Persistence of initial conditions in continental scale air quality simulations

NASA Astrophysics Data System (ADS)

Hogrefe, Christian; Roselle, Shawn J.; Bash, Jesse O.

2017-07-01

This study investigates the effect of initial conditions (IC) for pollutant concentrations in the atmosphere and soil on simulated air quality for two continental-scale Community Multiscale Air Quality (CMAQ) model applications. One of these applications was performed for springtime and the second for summertime. Results show that a spin-up period of ten days commonly used in regional-scale applications may not be sufficient to reduce the effects of initial conditions to less than 1% of seasonally-averaged surface ozone concentrations everywhere while 20 days were found to be sufficient for the entire domain for the spring case and almost the entire domain for the summer case. For the summer case, differences were found to persist longer aloft due to circulation of air masses and even a spin-up period of 30 days was not sufficient to reduce the effects of ICs to less than 1% of seasonally-averaged layer 34 ozone concentrations over the southwestern portion of the modeling domain. Analysis of the effect of soil initial conditions for the CMAQ bidirectional NH3 exchange model shows that during springtime they can have an important effect on simulated inorganic aerosols concentrations for time periods of one month or longer. The effects are less pronounced during other seasons. The results, while specific to the modeling domain and time periods simulated here, suggest that modeling protocols need to be scrutinized for a given application and that it cannot be assumed that commonly-used spin-up periods are necessarily sufficient to reduce the effects of initial conditions on model results to an acceptable level. What constitutes an acceptable level of difference cannot be generalized and will depend on the particular application, time period and species of interest. Moreover, as the application of air quality models is being expanded to cover larger geographical domains and as these models are increasingly being coupled with other modeling systems to better represent

Determination of Air Quality. Proceedings of the ACS Symposium on Determination of Air Quality.

ERIC Educational Resources Information Center

Mamantov, Gleb, Ed.; Shults, W. D., Ed.

Composed of data submitted by a variety of experts in the field, this book provides an introduction to air pollution control. It contains the proceedings of the American Chemical Society Symposium on Determination of Air Quality held in Los Angeles, California, April 1-2, 1971. Contributions from chemists, physicians, engineers, administrators,…

Electric-Field Instrument With Ac-Biased Corona Point

NASA Technical Reports Server (NTRS)

Markson, R.; Anderson, B.; Govaert, J.

1993-01-01

Measurements indicative of incipient lightning yield additional information. New instrument gives reliable readings. High-voltage ac bias applied to needle point through high-resistance capacitance network provides corona discharge at all times, enabling more-slowly-varying component of electrostatic potential of needle to come to equilibrium with surrounding air. High resistance of high-voltage coupling makes instrument insensitive to wind. Improved corona-point instrument expected to yield additional information assisting in safety-oriented forecasting of lighting.

Neutrophil elastase increases MUC5AC mRNA and protein expression in respiratory epithelial cells.

PubMed

Voynow, J A; Young, L R; Wang, Y; Horger, T; Rose, M C; Fischer, B M

1999-05-01

Chronic neutrophil-predominant inflammation and hypersecretion of mucus are common pathophysiological features of cystic fibrosis, chronic bronchitis, and viral- or pollution-triggered asthma. Neutrophils release elastase, a serine protease, that causes increased mucin production and secretion. The molecular mechanisms of elastase-induced mucin production are unknown. We hypothesized that as part of this mechanism, elastase upregulates expression of a major respiratory mucin gene, MUC5AC. A549, a human lung carcinoma cell line that expresses MUC5AC mRNA and protein, and normal human bronchial epithelial cells in an air-liquid interface culture were stimulated with neutrophil elastase. Neutrophil elastase increased MUC5AC mRNA levels in a time-dependent manner in both cell culture systems. Neutrophil elastase treatment also increased MUC5AC protein levels in A549 cells. The mechanism of MUC5AC gene regulation by elastase was determined in A549 cells. The induction of MUC5AC gene expression required serine protease activity; other classes of proteases had no effect on MUC5AC gene expression. Neutrophil elastase increased MUC5AC mRNA levels by enhancing mRNA stability. This is the first report of mucin gene regulation by this mechanism.

The Analysis for Energy Consumption of Marine Air Conditioning System Based on VAV and VWV

NASA Astrophysics Data System (ADS)

Xu, Sai Feng; Yang, Xing Lin; Le, Zou Ying

2018-06-01

For ocean-going vessels sailing in different areas on the sea, the change of external environment factors will cause frequent changes in load, traditional ship air-conditioning system is usually designed with a fixed cooling capacity, this design method causes serious waste of resources. A new type of sea-based air conditioning system is proposed in this paper, which uses the sea-based source heat pump system, combined with variable air volume, variable water technology. The multifunctional cabins' dynamic loads for a ship navigating in a typical Eurasian route were calculated based on Simulink. The model can predict changes in full voyage load. Based on the simulation model, the effects of variable air volume and variable water volume on the energy consumption of the air-conditioning system are analyzed. The results show that: When the VAV is coupled with the VWV, the energy saving rate is 23.2%. Therefore, the application of variable air volume and variable water technology to marine air conditioning systems can achieve economical and energy saving advantages.

Duct attachment and extension for an air conditioning unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lang, R.D.; Frenia, F.J.

1986-12-16

An apparatus is described for attaching a fixed duct extension to the discharge opening of an air conditioning unit, the unit slidably inserted in and removed from a fixed through-the-wall sleeve, for supplying conditioned air to the space containing the unit and an adjacent space comprising: a discharge plenum assembly adapted to be connected to the unit encase the discharge opening. The discharge plenum assembly defines an air flow path for the conditioned air discharged from the unit and includes a first housing member having a forward wall, a rear wall, and a pair of opposed side walls joining themore » front wall to the rear wall, and a second housing member having a top wall connected to a front wall. The top wall and the front wall are fixedly attached to the rear wall and the forward wall respectively of the first housing member and forming a duct outlet in one of the side walls. The top wall and the front wall of the second housing member and one of the pair of opposed side walls of the lower housing member having longitudinal flanges extending therefrom forming a C-like flange; a bracket removably secured to the through the wall sleeve having an outwardly extending flange member at the top of the bracket; and a duct extension means secured to the outwardly extending flange of the bracket near one end and to the wall of the adjacent space at the opposite end. The duct extension means has a collar at one end configured to engage with the C-like flange whereby the unit with the discharge plenum assembly attached thereto slidably engages with and disengages from the through-the-wall sleeve while the duct extension is secured to the bracket.« less

Thermal comfort in naturally ventilated and air-conditioned buildings in humid subtropical climate zone in China

NASA Astrophysics Data System (ADS)

Yang, Wei; Zhang, Guoqiang

2008-05-01

A thermal comfort field study has been carried out in five cities in the humid subtropical climate zone in China. The survey was performed in naturally ventilated and air-conditioned buildings during the summer season in 2006. There were 229 occupants from 111 buildings who participated in this study and 229 questionnaire responses were collected. Thermal acceptability assessment reveals that the indoor environment in naturally ventilated buildings could not meet the 80% acceptability criteria prescribed by ASHRAE Standard 55, and people tended to feel more comfortable in air-conditioned buildings with the air-conditioned occupants voting with higher acceptability (89%) than the naturally ventilated occupants (58%). The neutral temperatures in naturally ventilated and air-conditioned buildings were 28.3°C and 27.7°C, respectively. The range of accepted temperature in naturally ventilated buildings (25.0˜31.6°C) was wider than that in air-conditioned buildings (25.1˜30.3°C), which suggests that occupants in naturally ventilated buildings seemed to be more tolerant of higher temperatures. Preferred temperatures were 27.9°C and 27.3°C in naturally ventilated and air-conditioned buildings, respectively, both of which were 0.4°C cooler than neutral temperatures. This result suggests that people of hot climates may use words like “slightly cool” to describe their preferred thermal state. The relationship between draught sensation and indoor air velocity at different temperature ranges indicates that indoor air velocity had a significant influence over the occupants’ comfort sensation, and air velocities required by occupants increased with the increasing of operative temperatures. Thus, an effective way of natural ventilation which can create the preferred higher air movement is called for. Finally, the indoor set-point temperature of 26°C or even higher in air-conditioned buildings was confirmed as making people comfortable, which supports the regulation

Evaluation of Rankine cycle air conditioning system hardware by computer simulation

NASA Technical Reports Server (NTRS)

Healey, H. M.; Clark, D.

1978-01-01

A computer program for simulating the performance of a variety of solar powered Rankine cycle air conditioning system components (RCACS) has been developed. The computer program models actual equipment by developing performance maps from manufacturers data and is capable of simulating off-design operation of the RCACS components. The program designed to be a subroutine of the Marshall Space Flight Center (MSFC) Solar Energy System Analysis Computer Program 'SOLRAD', is a complete package suitable for use by an occasional computer user in developing performance maps of heating, ventilation and air conditioning components.

Heating, Ventilating, and Air Conditioning. Energy Technology Series.

ERIC Educational Resources Information Center

Center for Occupational Research and Development, Inc., Waco, TX.

This course in heating, ventilating, and air conditioning is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

Persistence of initial conditions in continental scale air quality ...

EPA Pesticide Factsheets

This study investigates the effect of initial conditions (IC) for pollutant concentrations in the atmosphere and soil on simulated air quality for two continental-scale Community Multiscale Air Quality (CMAQ) model applications. One of these applications was performed for springtime and the second for summertime. Results show that a spin-up period of ten days commonly used in regional-scale applications may not be sufficient to reduce the effects of initial conditions to less than 1% of seasonally-averaged surface ozone concentrations everywhere while 20 days were found to be sufficient for the entire domain for the spring case and almost the entire domain for the summer case. For the summer case, differences were found to persist longer aloft due to circulation of air masses and even a spin-up period of 30 days was not sufficient to reduce the effects of ICs to less than 1% of seasonally-averaged layer 34 ozone concentrations over the southwestern portion of the modeling domain. Analysis of the effect of soil initial conditions for the CMAQ bidirectional NH3 exchange model shows that during springtime they can have an important effect on simulated inorganic aerosols concentrations for time periods of one month or longer. The effects are less pronounced during other seasons. The results, while specific to the modeling domain and time periods simulated here, suggest that modeling protocols need to be scrutinized for a given application and that it cannot be assum

AC to DC Bridgeless Boost Converter for Ultra Low Input Energy Harvesting

NASA Astrophysics Data System (ADS)

Dawam, A. H. A.; Muhamad, M.

2018-03-01

This paper presents design of circuit which converts low input AC voltage to a higher output DC voltage. A buck-boost topology and boost topology are combined to condition cycle of an AC input voltage. the unique integration of a combining circuit of buck-boost and boost circuit have been proposed in order to introduce a new direct ac-dc power converter topology without conventional diode bridge rectifier. The converter achieved to convert a milli-volt scale of input AC voltage into a volt scale of output DC voltages which is from 400mV to 3.3V.

An Objective Estimation of Air-Bone-Gap in Cochlear Implant Recipients with Residual Hearing Using Electrocochleography.

PubMed

Koka, Kanthaiah; Saoji, Aniket A; Attias, Joseph; Litvak, Leonid M

2017-01-01

Although, cochlear implants (CI) traditionally have been used to treat individuals with bilateral profound sensorineural hearing loss, a recent trend is to implant individuals with residual low-frequency hearing. Notably, many of these individuals demonstrate an air-bone gap (ABG) in low-frequency, pure-tone thresholds following implantation. An ABG is the difference between audiometric thresholds measured using air conduction (AC) and bone conduction (BC) stimulation. Although, behavioral AC thresholds are straightforward to assess, BC thresholds can be difficult to measure in individuals with severe-to-profound hearing loss because of vibrotactile responses to high-level, low-frequency stimulation and the potential contribution of hearing in the contralateral ear. Because of these technical barriers to measuring behavioral BC thresholds in implanted patients with residual hearing, it would be helpful to have an objective method for determining ABG. This study evaluated an innovative technique for measuring electrocochleographic (ECochG) responses using the cochlear microphonic (CM) response to assess AC and BC thresholds in implanted patients with residual hearing. Results showed high correlations between CM thresholds and behavioral audiograms for AC and BC conditions, thereby demonstrating the feasibility of using ECochG as an objective tool for quantifying ABG in CI recipients.

Conditioning of inspired air by a hygroscopic condenser humidifier.

PubMed

Primiano, F P; Moranz, M E; Montague, F W; Miller, R B; Sachs, D P

1984-08-01

The heat and water content of inspired air is critical to the pulmonary viability of patients with artificial airways. By continuously measuring gas conditions in the ventilator circuits of 6 adult ICU patients, we studied the heat and water reclaimed from expired air by a hygroscopic condenser humidifier (HCH) in the circuit. Temperature, partial pressure of water vapor (PH2O) and relative humidity (RH) were determined at the tracheal outlet of the endotracheal tube. The HCH was 63% efficient; the end-inspiratory gas delivered to the patients averaged 30.9 degrees C with a PH2O of 32.5 mm Hg and an RH of 97.3% or, equivalently, an RH of 69.2% referenced to 37 degrees C. These values are lower than those reported in the literature for gas in the trachea during nose breathing of ambient air, but greater than the values reported for mouth breathing of ambient air.

Grain Refinement of AZ31 Magnesium Alloy Weldments by AC Pulsing Technique

NASA Astrophysics Data System (ADS)

Kishore Babu, N.; Cross, C. E.

2012-11-01

The current study has investigated the influence of alternating current pulsing on the structure and mechanical properties of AZ31 magnesium alloy gas tungsten arc (GTA) weldments. Autogenous full penetration bead-on-plate GTA welds were made under a variety of conditions including variable polarity (VP), variable polarity mixed (VPM), alternating current (AC), and alternating current pulsing (ACPC). AC pulsing resulted in significant refinement of weld metal when compared with the unpulsed conditions. AC pulsing leads to relatively finer and more equiaxed grain structure in GTA welds. In contrast, VP, VPM, and AC welding resulted in predominantly columnar grain structures. The reason for this grain refinement may be attributed to the periodic variations in temperature gradient and solidification rate associated with pulsing as well as weld pool oscillation observed in the ACPC welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, tensile strength, and ductility.

Local Air Quality Conditions and Forecasts

MedlinePlus

... Monitor Location Archived Maps by Region Canada Air Quality Air Quality on Google Earth Links A-Z About AirNow AirNow International Air Quality Action Days / Alerts AirCompare Air Quality Index (AQI) ...

Reducing indoor air pollution by air conditioning is associated with improvements in cardiovascular health among the general population.

PubMed

Lin, Lian-Yu; Chuang, Hsiao-Chi; Liu, I-Jung; Chen, Hua-Wei; Chuang, Kai-Jen

2013-10-01

Indoor air pollution is associated with cardiovascular effects, however, little is known about the effects of improving indoor air quality on cardiovascular health. The aim of this study was to explore whether improving indoor air quality through air conditioning can improve cardiovascular health in human subjects. We recruited a panel of 300 healthy subjects from Taipei, aged 20 and over, to participate in six home visits each, to measure a variety of cardiovascular endpoints, including high sensitivity-C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), fibrinogen in plasma and heart rate variability (HRV). Indoor particles and total volatile organic compounds (VOCs) were measured simultaneously at the participant's home during each visit. Three exposure conditions were investigated in this study: participants were requested to keep their windows open during the first two visits, close their windows during the next two visits, and close the windows and turn on their air conditioners during the last two visits. We used linear mixed-effects models to associate the cardiovascular endpoints with individual indoor air pollutants. The results showed that increases in hs-CRP, 8-OHdG and fibrinogen, and decreases in HRV indices were associated with increased levels of indoor particles and total VOCs in single-pollutant and two-pollutant models. The effects of indoor particles and total VOCs on cardiovascular endpoints were greatest during visits with the windows open. During visits with the air conditioners turned on, no significant changes in cardiovascular endpoints were observed. In conclusion, indoor air pollution is associated with inflammation, oxidative stress, blood coagulation and autonomic dysfunction. Reductions in indoor air pollution and subsequent improvements in cardiovascular health can be achieved by closing windows and turning on air conditioners at home. Copyright © 2013 Elsevier B.V. All rights reserved.

The Design of The Monitoring Tools Of Clean Air Condition And Dangerous Gas CO, CO2 CH4 In Chemical Laboratory By Using Fuzzy Logic Based On Microcontroller

NASA Astrophysics Data System (ADS)

Widodo, Slamet; Miftakul, Amin M.; Sutrisman, Adi

2018-02-01

There are many phenomena that human are exposed to toxins from certain types such as of CO2, CO2 and CH4 gases. The device used to detect large amounts of CO, CO2, and CH4 gas in air in enclosed spaces using MQ 135 gas sensors of different types based on the three sensitivity of the Gas. The results of testing the use of sensors MQ 135 on the gas content of CO, CO2 and CH4 received by the sensor is still in the form of ppm based on the maximum ppm detection range of each sensor. Active sensor detects CO 120 ppm gas, CO2 1600 ppm and CH4 1ppm "standby 1" air condition with intermediate rotary fan. Active sensor detects CO 30 ppm gas, CO2 490 ppm and CH4 7 ppm "Standby 2" with low rotating fan output. Fuzzy rulebase logic for motor speed when gas detection sensor CO, CO2, and CH4 output controls the motion speed of the fan blower. Active sensors detect CO 15 ppm, CO2 320 ppm and CH4 45 ppm "Danger" air condition with high fan spin fan. At the gas level of CO 15 ppm, CO2 390 ppm and CH4 3 ppm detect "normal" AC sensor with fan output stop spinning.

Total environmental warming impact (TEWI) calculations for alternative automative air-conditioning systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sand, J.R.; Fischer, S.K.

1997-01-01

The Montreal Protocol phase-out of chlorofluorocarbons (CFCs) has required manufacturers to develop refrigeration and air-conditioning systems that use refrigerants that can not damage stratospheric ozone. Most refrigeration industries have adapted their designs to use hydrochlorofluorocarbon (HCFC) or hydrofluorocarbon (HFC) refrigerants; new automobile air- conditioning systems use HFC-134a. These industries are now being affected by scientific investigations of greenhouse warming and questions about the effects of refrigerants on global warming. Automobile air-conditioning has three separate impacts on global warming; (1) the effects of refrigerant inadvertently released to the atmosphere from accidents, servicing, and leakage; (2) the efficiency of the cooling equipmentmore » (due to the emission of C0{sub 2} from burning fuel to power the system); and (3) the emission of C0{sub 2} from burning fuel to transport the system. The Total Equivalent Warming Impact (TEWI) is an index that should be used to compare the global warming effects of alternative air-conditioning systems because it includes these contributions from the refrigerant, cooling efficiency, and weight. This paper compares the TEWI of current air-conditioning systems using HFC-134a with that of transcritical vapor compression system using carbon dioxide and systems using flammable refrigerants with secondary heat transfer loops. Results are found to depend on both climate and projected efficiency of C0{sub 2}systems. Performance data on manufacturing prototype systems are needed to verify the potential reductions in TEWI. Extensive field testing is also required to determine the performance, reliability, and ``serviceability`` of each alternative to HFC-134a to establish whether the potential reduction of TEWI can be achieved in a viable consumer product.« less

40 CFR 86.161-00 - Air conditioning environmental test facility ambient requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... each point of a 0.5 meter grid over the entire footprint of the test vehicle at the elevation of one... impractical, air flow of 2 mph or less will be allowed at 0 mph vehicle speed. (3) The fan air flow velocity..., within the test cell, during all phases of the air conditioning test sequence to 95 ±2 °F on average and...

Combustion and NOx emission characteristics with respect to staged-air damper opening in a 600 MWe down-fired pulverized-coal furnace under deep-air-staging conditions.

PubMed

Kuang, Min; Li, Zhengqi; Wang, Zhihua; Jing, Xinjing; Liu, Chunlong; Zhu, Qunyi; Ling, Zhongqian

2014-01-01

Deep-air-staging combustion conditions, widely used in tangential-fired and wall-arranged furnaces to significantly reduce NOx emissions, are premature up to now in down-fired furnaces that are designed especially for industry firing low-volatile coals such as anthracite and lean coal. To uncover combustion and NOx emission characteristics under deep-air-staging conditions within a newly operated 600 MWe down-fired furnace and simultaneously understand the staged-air effect on the furnace performance, full-load industrial-size measurements taken of gas temperatures and species concentrations in the furnace, CO and NOx emissions in flue gas, and carbon in fly ash were performed at various staged-air damper openings of 10%, 20%, 30%, and 50%. Increasing the staged-air damper opening, gas temperatures along the flame travel (before the flame penetrating the staged-air zone) increased initially but then decreased, while those in the staged-air zone and the upper part of the hopper continuously decreased and increased, respectively. On opening the staged-air damper to further deepen the air-staging conditions, O2 content initially decreased but then increased in both two near-wall regions affected by secondary air and staged air, respectively, whereas CO content in both two regions initially increased but then decreased. In contrast to the conventional understanding about the effects of deep-air-staging conditions, here increasing the staged-air damper opening to deepen the air-staging conditions essentially decreased the exhaust gas temperature and carbon in fly ash and simultaneously increased both NOx emissions and boiler efficiency. In light of apparently low NOx emissions and high carbon in fly ash (i.e., 696-878 mg/m(3) at 6% O2 and 9.81-13.05%, respectively) developing in the down-fired furnace under the present deep-air-staging conditions, further adjustments such as enlarging the staged-air declination angle to prolong pulverized-coal residence times in the

40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

Code of Federal Regulations, 2012 CFR

2012-07-01

... determine a refrigerant leakage rate in grams per year from vehicle-based air conditioning units. The... using the following equation: Grams/YRTOT = Grams/YRRP + Grams/YRSP + Grams/YRFH + Grams/YRMC + Grams/YRC Where: Grams/YRTOT = Total air conditioning system emission rate in grams per year and rounded to...

64. INTERIOR VIEW LOOKING DOWN LENGTH OF AIR CONDITIONING EQUIPMENT ...

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

64. INTERIOR VIEW LOOKING DOWN LENGTH OF AIR CONDITIONING EQUIPMENT REPAIR SHOP. - Baltimore & Ohio Railroad, Mount Clare Shops, South side of Pratt Street between Carey & Poppleton Streets, Baltimore, Independent City, MD

10. Building 105, Facilities Engineering Building, 1830, interior, air condition ...

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

10. Building 105, Facilities Engineering Building, 1830, interior, air condition repair shop, S end of building, looking N. - Watervliet Arsenal, Building 105, South Broadway, on Hudson River, Watervliet, Albany County, NY

Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

PubMed Central

Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

2015-01-01

In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process. PMID:26580660

Hollow Fiber Membrane Dehumidification Device for Air Conditioning System.

PubMed

Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

2015-11-16

In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18-22 g/m³ to a range of 13.5-18.3 g/m³. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

Development of software to improve AC power quality on large spacecraft

NASA Technical Reports Server (NTRS)

Kraft, L. Alan

1991-01-01

To insure the reliability of a 20 kHz, AC power system on spacecraft, it is essential to analyze its behavior under many adverse operating conditions. Some of these conditions include overloads, short circuits, switching surges, and harmonic distortions. Harmonic distortions can cause malfunctions in equipment that the power system is supplying, and during extreme distortions such as voltage resonance, it can cause equipment and insulation failures due to the extreme peak voltages. HARMFLO, a power flow computer program, which was capable of analyzing harmonic conditions on three phase, balanced, 60 Hz, AC power systems, was modified to analyze single phase, 20 kHz, AC power systems. Since almost all of the equipment used on spacecraft power systems is electrically different from equipment used on terrestrial power systems, it was also necessary to develop mathematical models for the equipment to be used on the spacecraft. The results are that (1) the harmonic power now has a model of a single phase, voltage controlled, full wave rectifier; and (2) HARMFLO was ported to the SUN workstation platform.

Low Offset AC Correlator.

DTIC Science & Technology

This patent describes a low offset AC correlator avoids DC offset and low frequency noise by frequency operating the correlation signal so that low...noise, low level AC amplification can be substituted for DC amplification. Subsequently, the high level AC signal is demodulated to a DC level. (Author)

Bi-level Optimization Method of Air-conditioning System Based on Office Building Energy Storage Characteristics

NASA Astrophysics Data System (ADS)

Wang, Qingze; Chen, Xingying; Ji, Li; Liao, Yingchen; Yu, Kun

2017-05-01

The air-conditioning system of office building is a large power consumption terminal equipment, whose unreasonable operation mode leads to low energy efficiency. Realizing the optimization of the air-conditioning system has become one of the important research contents of the electric power demand response. In this paper, in order to save electricity cost and improve energy efficiency, bi-level optimization method of air-conditioning system based on TOU price is put forward by using the energy storage characteristics of the office building itself. In the upper level, the operation mode of the air-conditioning system is optimized in order to minimize the uses’ electricity cost in the premise of ensuring user’ comfort according to the information of outdoor temperature and TOU price, and the cooling load of the air-conditioning is output to the lower level; In the lower level, the distribution mode of cooling load among the multi chillers is optimized in order to maximize the energy efficiency according to the characteristics of each chiller. Finally, the experimental results under different modes demonstrate that the strategy can improve the energy efficiency of chillers and save the electricity cost for users.

Air Conditioning, Heating, and Refrigeration. Competency-Based Curriculum Manual.

ERIC Educational Resources Information Center

Gourley, Frank A., Jr.

This manual was developed to serve as an aid to administrators and instructors involved with postsecondary air conditioning, heating, and refrigeration programs. The first of six chapters contains general information on program implementation, the curriculum design, facilities and equipment requirements, and textbooks and references. Chapter 2…

Experimental and theoretical characterization of an AC electroosmotic micromixer.

PubMed

Sasaki, Naoki; Kitamori, Takehiko; Kim, Haeng-Boo

2010-01-01

We have reported on a novel microfluidic mixer based on AC electroosmosis. To elucidate the mixer characteristics, we performed detailed measurements of mixing under various experimental conditions including applied voltage, frequency and solution viscosity. The results are discussed through comparison with results obtained from a theoretical model of AC electroosmosis. As predicted from the theoretical model, we found that a larger voltage (approximately 20 V(p-p)) led to more rapid mixing, while the dependence of the mixing on frequency (1-5 kHz) was insignificant under the present experimental conditions. Furthermore, the dependence of the mixing on viscosity was successfully explained by the theoretical model, and the applicability of the mixer in viscous solution (2.83 mPa s) was confirmed experimentally. By using these results, it is possible to estimate the mixing performance under given conditions. These estimations can provide guidelines for using the mixer in microfluidic chemical analysis.

High Efficiency Variable Speed Versatile Power Air Conditioning System for Military Vehicles

DTIC Science & Technology

2013-08-01

MOBILITY (P&M) MINI-SYMPOSIUM AUGUST 21-22, 2013 - TROY , MICHIGAN High efficiency variable speed versatile power air conditioning system for...power draw was measured using a calibrated Watt meter. The schematic of the setup is shown in Figure 5 and the setup is shown in Figure 6. Figure...Rocky Research environmental chamber. Cooling Capacity was directly measured in Btu/hr or Watts via measuring the Air flow velocity and the air

Air Conditioning, Heating, and Ventilating: Construction, Supervision, and Inspection. Course of Study.

ERIC Educational Resources Information Center

Messer, John D.

This course of study on air conditioning, heating, and ventilating is part of a construction, supervision, and inspection series, which provides instructional materials for community or junior college technical courses in the inspection program. Material covered pertains to: piping and piping systems; air movers; boilers; heat exchangers; cooling…

AC Loss Analysis of MgB2-Based Fully Superconducting Machines

NASA Astrophysics Data System (ADS)

Feddersen, M.; Haran, K. S.; Berg, F.

2017-12-01

Superconducting electric machines have shown potential for significant increase in power density, making them attractive for size and weight sensitive applications such as offshore wind generation, marine propulsion, and hybrid-electric aircraft propulsion. Superconductors exhibit no loss under dc conditions, though ac current and field produce considerable losses due to hysteresis, eddy currents, and coupling mechanisms. For this reason, many present machines are designed to be partially superconducting, meaning that the dc field components are superconducting while the ac armature coils are conventional conductors. Fully superconducting designs can provide increases in power density with significantly higher armature current; however, a good estimate of ac losses is required to determine the feasibility under the machines intended operating conditions. This paper aims to characterize the expected losses in a fully superconducting machine targeted towards aircraft, based on an actively-shielded, partially superconducting machine from prior work. Various factors are examined such as magnet strength, operating frequency, and machine load to produce a model for the loss in the superconducting components of the machine. This model is then used to optimize the design of the machine for minimal ac loss while maximizing power density. Important observations from the study are discussed.

Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV) systems.

PubMed

Ng, Bing Feng; Xiong, Jin Wen; Wan, Man Pun

2017-01-01

The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM) indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop) that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV) systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency.

Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV) systems

PubMed Central

Xiong, Jin Wen; Wan, Man Pun

2017-01-01

The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM) indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop) that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV) systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency. PMID:28594862

AC application of second generation HTS wire

NASA Astrophysics Data System (ADS)

Thieme, C. L. H.; Gagnon, K.; Voccio, J.; Aized, D.; Claassen, J.

2008-02-01

For the production of Second Generation (2G) YBCO High Temperature Superconductor wire American Superconductor uses a wide-strip MOD-YBCO/RABiTSTM process, a low-cost approach for commercial manufacturing. It can be engineered with a high degree of flexibility to manufacture practical 2G conductors with architectures and properties tailored for specific applications and operating conditions. For ac applications conductor and coil design can be geared towards low hysteretic losses. For applications which experience high frequency ac fields, the stabilizer needs to be adjusted for low eddy current losses. For these applications a stainless-steel laminate is used. An example is a Low Pass Filter Inductor which was developed and built in this work.

Children's well-being at schools: Impact of climatic conditions and air pollution.

PubMed

Salthammer, Tunga; Uhde, Erik; Schripp, Tobias; Schieweck, Alexandra; Morawska, Lidia; Mazaheri, Mandana; Clifford, Sam; He, Congrong; Buonanno, Giorgio; Querol, Xavier; Viana, Mar; Kumar, Prashant

2016-09-01

Human civilization is currently facing two particular challenges: population growth with a strong trend towards urbanization and climate change. The latter is now no longer seriously questioned. The primary concern is to limit anthropogenic climate change and to adapt our societies to its effects. Schools are a key part of the structure of our societies. If future generations are to take control of the manifold global problems, we have to offer our children the best possible infrastructure for their education: not only in terms of the didactic concepts, but also with regard to the climatic conditions in the school environment. Between the ages of 6 and 19, children spend up to 8h a day in classrooms. The conditions are, however, often inacceptable and regardless of the geographic situation, all the current studies report similar problems: classrooms being too small for the high number of school children, poor ventilation concepts, considerable outdoor air pollution and strong sources of indoor air pollution. There have been discussions about a beneficial and healthy air quality in classrooms for many years now and in recent years extensive studies have been carried out worldwide. The problems have been clearly outlined on a scientific level and there are prudent and feasible concepts to improve the situation. The growing number of publications also highlights the importance of this subject. High carbon dioxide concentrations in classrooms, which indicate poor ventilation conditions, and the increasing particle matter in urban outdoor air have, in particular, been identified as primary causes of poor indoor air quality in schools. Despite this, the conditions in most schools continue to be in need of improvement. There are many reasons for this. In some cases, the local administrative bodies do not have the budgets required to address such concerns, in other cases regulations and laws stand in contradiction to the demands for better indoor air quality, and sometimes

Commentary: Air-conditioning as a risk for increased use of healthservices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendell, Mark J.

2004-06-01

In this issue of the journal, Preziosi et al. [2004] report the first study to assess differences in the utilization of health care related to the presence of air-conditioning in office workplaces. Although the study was simple and cross-sectional, the data variables from questionnaires, and the findings subject to a variety of questions, the findings are striking enough to deserve clarification. The study used a large random national sample of French women assembled for another purpose (to study antioxidant nutrients and prevention of cancer and cardiovascular disease). Participants reported health services and health events in monthly questionnaires over 1 year,more » and in one questionnaire in the middle of that period also reported whether air-conditioning was in use at their workplace. Fifteen percent of participants reported air-conditioning at work. Analyses adjusting for age and smoking status of participants found increases in most outcomes assessed: use of specific kinds of physicians, sickness absence, and hospital stays. While the increases in odds ratios (OR) and 95% confidence intervals (CI) were statistically significant for only otorhinolaryngology [OR (95% CI) = 2.33 (1.35-4.04)] and sickness absence [1.70 (1.13-2.58)], other increases were notable--dermatology [1.6 (0.98-2.65)]; hospital stay [1.51 (0.92-2.45)], and pneumonology [2.10 (0.65-6.82)]. The least elevated outcomes were for general practice medicine [0.99 (0.65-1.48)] and global medical visits [1.18 (0.67-2.07)]. [Preziosi et al., 2004 ,(Table 2)] Odds ratios for relatively common health outcomes often lie farther from the null than the risk ratios most useful for quantifying the increase in risk. Risk ratios, or prevalence ratios (PRs, the equivalent measure of effect for cross-sectional data), have seldom been used because of the convenience and availability of logistic regression models that estimate odds ratios. With baseline prevalences ranging up to 85.7% in the data from

Modeling validation and control analysis for controlled temperature and humidity of air conditioning system.

PubMed

Lee, Jing-Nang; Lin, Tsung-Min; Chen, Chien-Chih

2014-01-01

This study constructs an energy based model of thermal system for controlled temperature and humidity air conditioning system, and introduces the influence of the mass flow rate, heater and humidifier for proposed control criteria to achieve the controlled temperature and humidity of air conditioning system. Then, the reliability of proposed thermal system model is established by both MATLAB dynamic simulation and the literature validation. Finally, the PID control strategy is applied for controlling the air mass flow rate, humidifying capacity, and heating, capacity. The simulation results show that the temperature and humidity are stable at 541 sec, the disturbance of temperature is only 0.14 °C, 0006 kg(w)/kg(da) in steady-state error of humidity ratio, and the error rate is only 7.5%. The results prove that the proposed system is an effective controlled temperature and humidity of an air conditioning system.

Modeling Validation and Control Analysis for Controlled Temperature and Humidity of Air Conditioning System

PubMed Central

Lee, Jing-Nang; Lin, Tsung-Min

2014-01-01

This study constructs an energy based model of thermal system for controlled temperature and humidity air conditioning system, and introduces the influence of the mass flow rate, heater and humidifier for proposed control criteria to achieve the controlled temperature and humidity of air conditioning system. Then, the reliability of proposed thermal system model is established by both MATLAB dynamic simulation and the literature validation. Finally, the PID control strategy is applied for controlling the air mass flow rate, humidifying capacity, and heating, capacity. The simulation results show that the temperature and humidity are stable at 541 sec, the disturbance of temperature is only 0.14°C, 0006 kgw/kgda in steady-state error of humidity ratio, and the error rate is only 7.5%. The results prove that the proposed system is an effective controlled temperature and humidity of an air conditioning system. PMID:25250390

Flow and air conditioning simulations of computer turbinectomized nose models.

PubMed

Pérez-Mota, J; Solorio-Ordaz, F; Cervantes-de Gortari, J

2018-04-16

Air conditioning for the human respiratory system is the most important function of the nose. When obstruction occurs in the nasal airway, turbinectomy is used to correct such pathology. However, mucosal atrophy may occur sometime after this surgery when it is overdone. There is not enough information about long-term recovery of nasal air conditioning performance after partial or total surgery. The purpose of this research was to assess if, based on the flow and temperature/humidity characteristics of the air intake to the choana, partial resection of turbinates is better than total resection. A normal nasal cavity geometry was digitized from tomographic scans and a model was printed in 3D. Dynamic (sinusoidal) laboratory tests and computer simulations of airflow were conducted with full agreement between numerical and experimental results. Computational adaptations were subsequently performed to represent six turbinectomy variations and a swollen nasal cavity case. Streamlines along the nasal cavity and temperature and humidity distributions at the choana indicated that the middle turbinate partial resection is the best alternative. These findings may facilitate the diagnosis of nasal obstruction and can be useful both to plan a turbinectomy and to reduce postoperative discomfort. Graphical Abstract ᅟ.

Influence of Boundary Conditions on Simulated U.S. Air Quality

EPA Science Inventory

One of the key inputs to regional-scale photochemical models frequently used in air quality planning and forecasting applications are chemical boundary conditions representing background pollutant concentrations originating outside the regional modeling domain. A number of studie...

Note: A phase synchronization photography method for AC discharge.

PubMed

Wu, Zhicheng; Zhang, Qiaogen; Ma, Jingtan; Pang, Lei

2018-05-01

To research discharge physics under AC voltage, a phase synchronization photography method is presented. By using a permanent-magnet synchronous motor to drive a photography mask synchronized with a discharge power supply, discharge images in a specific phase window can be recorded. Some examples of discharges photographed by this method, including the corona discharge in SF 6 and the corona discharge along the air/epoxy surface, demonstrate the feasibility of this method. Therefore, this method provides an effective tool for discharge physics researchers.

Note: A phase synchronization photography method for AC discharge

NASA Astrophysics Data System (ADS)

Wu, Zhicheng; Zhang, Qiaogen; Ma, Jingtan; Pang, Lei

2018-05-01

To research discharge physics under AC voltage, a phase synchronization photography method is presented. By using a permanent-magnet synchronous motor to drive a photography mask synchronized with a discharge power supply, discharge images in a specific phase window can be recorded. Some examples of discharges photographed by this method, including the corona discharge in SF6 and the corona discharge along the air/epoxy surface, demonstrate the feasibility of this method. Therefore, this method provides an effective tool for discharge physics researchers.

Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Williamson, James M.; Trump, Darryl D.; Bletzinger, Peter; Ganguly, Biswa N.

2006-10-01

A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s-1. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ~3 × 1015 cm-3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ~8.5 × 1015 cm-3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level.

75 FR 60493 - Advisory Circular 120-79A, Developing and Implementing an Air Carrier Continuing Analysis and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-30

... and Implementing an Air Carrier Continuing Analysis and Surveillance System AGENCY: Federal Aviation... Analysis and Surveillance System''. This new advisory circular (AC) updates AC 120-79 originally issued on... Analysis and Surveillance System (CASS) required for commercial operators and air carriers certificated...

State Skill Standards: Heating, Ventilation, Air Conditioning, and Refrigeration

ERIC Educational Resources Information Center

Ball, Larry; Soukup, Dennis

2006-01-01

The Department of Education has undertaken an ambitious effort to develop statewide career and technical education skill standards. The standards in this document are for Heating, Ventilation, Air Conditioning and Refrigeration (HVAC&R) programs and are designed to clearly state what the student should know and be able to do upon completion of…

Heating, Air-Conditioning, and Refrigeration Technician. National Skill Standards.

ERIC Educational Resources Information Center

Vocational Technical Education Consortium of States, Decatur, GA.

This guide contains information on the knowledge and skills identified by industry as essential to the job performance of heating, air-conditioning, and refrigeration technicians. It is intended to assist training providers in public and private institutions, as well as in industry, to develop and implement training that will provide workers with…

[Air conducted ocular VEMP: I. Determination of a method and application in normal patients].

PubMed

Walther, L E; Schaaf, H; Sommer, D; Hörmann, K

2011-07-01

Air conducted (AC) cervical vestibular evoked myogenic potentials (AC cVEMP) and air conducted ocular VEMP (AC oVEMP) may be used for measurement of otolith function. However AC oVEMP are few examined till now. The aim of this pilot study was to apply a method for use of AC oVEMP in clinical practice. AC oVEMP were recorded in healthy voluntary people (n=20) using intense AC-sound stimulation (500 Hz tone bursts, 100 dB nHL). Thermal irrigation and AC cVEMP were normal as including criteria. Values were evaluated statistically. AC oVEMP were recorded in all healthy patients. Mean and standard deviation for the first negative peak was 11.35±1.00 ms and for the first negative peak 16.30±1.10 ms. The mean amplitudes were 7.70±4.50 μV. The stability of n10 and p15 component was the same. AC oVEMP can be easy and fast obtained. N10 and p15 latencies may used as parameter for clinical interpretation. Amplitude fluctuations are relatively large. Results can be used in further clinical investigation of AC oVEMP. © Georg Thieme Verlag KG Stuttgart · New York.

Ecological succession of the microbial communities of an air-conditioning cooling coil in the tropics.

PubMed

Acerbi, E; Chénard, C; Miller, D; Gaultier, N E; Heinle, C E; Chang, V W-C; Uchida, A; Drautz-Moses, D I; Schuster, S C; Lauro, F M

2017-03-01

Air-conditioning systems harbor microorganisms, potentially spreading them to indoor environments. While air and surfaces in air-conditioning systems are periodically sampled as potential sources of indoor microbes, little is known about the dynamics of cooling coil-associated communities and their effect on the downstream airflow. Here, we conducted a 4-week time series sampling to characterize the succession of an air-conditioning duct and cooling coil after cleaning. Using an universal primer pair targeting hypervariable regions of the 16S/18S ribosomal RNA, we observed a community succession for the condensed water, with the most abundant airborne taxon Agaricomycetes fungi dominating the initial phase and Sphingomonas bacteria becoming the most prevalent taxa toward the end of the experiment. Duplicate air samples collected upstream and downstream of the coil suggest that the system does not act as ecological filter or source/sink for specific microbial taxa during the duration of the experiment. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

System and method for conditioning intake air to an internal combustion engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sellnau, Mark C.

A system for conditioning the intake air to an internal combustion engine includes a means to boost the pressure of the intake air to the engine and a liquid cooled charge air cooler disposed between the output of the boost means and the charge air intake of the engine. Valves in the coolant system can be actuated so as to define a first configuration in which engine cooling is performed by coolant circulating in a first coolant loop at one temperature, and charge air cooling is performed by coolant flowing in a second coolant loop at a lower temperature. Themore » valves can be actuated so as to define a second configuration in which coolant that has flowed through the engine can be routed through the charge air cooler. The temperature of intake air to the engine can be controlled over a wide range of engine operation.« less

Athletes Do Not Condition Inspired Air More Effectively than Nonathletes during Hyperpnea.

PubMed

Boulet, Louis-Philippe; Moreau, Simon-Pierre; Villeneuve, HÉlÈNE; Turmel, Julie

2017-01-01

Endurance athletes have a high prevalence of airway diseases, some possibly representing adaptive mechanisms to the need of conditioning large volumes of inspired air during high ventilation in specific environments. The aim of this study is to assess the ability to condition (warm and humidify) inspired air in athletes by measuring the difference between inhaled and exhaled air temperature (ΔT) during and after eucapnic voluntary hyperpnea (EVH) test. Twenty-three endurance athletes from various sports, 12 with airway hyperresponsiveness (AHR) and/or exercise-induced bronchoconstriction (EIB) (A+), 11 without AHR and/or EIB (A-), 12 nonathletes with AHR and/or EIB (C+), and 11 nonathletes without AHR and/or EIB (C-) were recruited. All subjects attended the laboratory on three occasions, twice for baseline characterization, including questionnaires, pulmonary function, methacholine bronchoprovocation, allergy skin prick tests, exhaled nitric oxide measurement, and a standard EVH, and once to perform a modified EVH to assess ΔT. Inspired and expired air temperatures were measured with a high-precision probe during EVH and at regular intervals until 30 min after the end of the test. The global ΔT during the EVH was +5.8°C ± 1.5°C and +4.7°C ± 1.5°C during the 30 min after the EVH. No difference was found between groups for either the ΔT or the slope of ΔT, during and after the EVH. This study shows no evidence of improved capacity to condition inspired air in endurance athletes, which could have suggested an increased bronchial blood flow or another adaptive mechanism. The absence of an adaptive mechanism could therefore contribute to airway damage observed in athletes in allowing colder but mainly dryer air to penetrate deeper in the lung.

The effect of environmental parameters to dust concentration in air-conditioned space

NASA Astrophysics Data System (ADS)

Ismail, A. M. M.; Manssor, N. A. S.; Nalisa, A.; Yahaya, N.

2017-08-01

Malaysia has a wet and hot climate, therefore most of the spaces are air conditioned. The environment might affect dust concentration inside a space and affect the indoor air quality (IAQ). The main objective of this study is to study the dust concentration collected inside enclosed air-conditioned space. The measurement was done physically at four selected offices and two classrooms using a number of equipment to measure the dust concentration and environmental parameters which are temperature and relative air humidity. It was found that the highest dust concentration produced in office (temperature of 24.7°C, relative humidity of 66.5%) is 0.075 mg/m3, as compared to classroom, the highest dust concentration produced is 0.060 mg/m3 office (temperature of 25.9°C, relative humidity of 64.0%). However, both measurements show that value still within the safety level set by DOSH Malaysia (2005-2010) and ASHRAE 62.2 2016. The office contained higher dust concentration compared to classroom because of frequent movement transpires daily due to the functional of the offices.

Reconstitutional Mutagenesis of the Maize P Gene by Short-Range Ac Transpositions

PubMed Central

Moreno, M. A.; Chen, J.; Greenblatt, I.; Dellaporta, S. L.

1992-01-01

The tendency for Ac to transpose over short intervals has been utilized to develop insertional mutagenesis and fine structure genetic mapping strategies in maize. We recovered excisions of Ac from the P gene and insertions into nearby chromosomal sites. These closely linked Ac elements reinserted into the P gene, reconstituting over 250 unstable variegated alleles. Reconstituted alleles condition a variety of variegation patterns that reflect the position and orientation of Ac within the P gene. Molecular mapping and DNA sequence analyses have shown that reinsertion sites are dispersed throughout a 12.3-kb chromosomal region in the promoter, exons and introns of the P gene, but in some regions insertions sites were clustered in a nonrandom fashion. Transposition profiles and target site sequence data obtained from these studies have revealed several features of Ac transposition including its preference for certain target sites. These results clearly demonstrate the tendency of Ac to transpose to nearby sites in both proximal and distal directions from the donor site. With minor modifications, reconstitutional mutagenesis should be applicable to many Ac-induced mutations in maize and in other plant species and can possibly be extended to other eukaryotic transposon systems as well. PMID:1325389

FLUIDIC AC AMPLIFIERS.

DTIC Science & Technology

Several fluidic tuned AC Amplifiers were designed and tested. Interstage tuning and feedback designs are considered. Good results were obtained...corresponding Q’s as high as 12. Element designs and test results of one, two, and three stage amplifiers are presented. AC Modulated Carrier Systems

Installation of PMV Operation Program in DDC Controller and Air Conditioning Control Using PMV Directly as Set Point

NASA Astrophysics Data System (ADS)

Haramoto, Ken-Ichi

In general, air conditioning control in a building is operated mainly by indoor air temperature control. Although the operators of the machine in the building accepted a claim for indoor air temperature presented by the building inhabitants, the indoor conditions have been often too cool or warm. Therefore, in an attempt to create better thermal environments, the author paid attention to the PMV that is a thermal comfort index. And then, the possibility of air conditioning control using the PMV directly as the set point was verified by employing actual equipment in an air conditioning testing room and an office building. Prior to the execution of this control, the operation program of the PMV was installed in a DDC controller for the air conditioning control. And information from indoor sensors and so on was inputted to the controller, and the computed PMV was used as the feedback variable.

Air filtration systems and restrictive access conditions improve indoor air quality in clinical units: Penicillium as a general indicator of hospital indoor fungal levels.

PubMed

Araujo, Ricardo; Cabral, João Paulo; Rodrigues, Acácio Gonçalves

2008-03-01

High-efficiency particulate air (HEPA) filters do not completely prevent nosocomial fungal infections. The first aim of this study was to evaluate the impact of different filters and access conditions upon airborne fungi in hospital facilities. Additionally, this study identified fungal indicators of indoor air concentrations. Eighteen rooms and wards equipped with different air filter systems, and access conditions were sampled weekly, during 16 weeks. Tap water samples were simultaneously collected. The overall mean concentration of atmospheric fungi for all wards was 100 colony forming units/m(3). We found a direct proportionality between the levels of the different fungi in the studied atmospheres. Wards with HEPA filters at positive air flow yielded lower fungal levels. Also, the existence of an anteroom and the use of protective clothes were associated to the lowest fungal levels. Principal component analysis showed that penicillia afforded the best separation between wards' air fungal levels. Fungal strains were rarely recovered from tap water samples. In addition to air filtration systems, some access conditions to hospital units, like presence of anteroom and use of protective clothes, may prevent high fungal air load. Penicillia can be used as a general indicator of indoor air fungal levels at Hospital S. João.

40 CFR 52.2581 - Significant deterioration of air quality.

Code of Federal Regulations, 2010 CFR

2010-07-01

... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

40 CFR 52.2581 - Significant deterioration of air quality.

Code of Federal Regulations, 2011 CFR

2011-07-01

... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

40 CFR 52.2581 - Significant deterioration of air quality.

Code of Federal Regulations, 2013 CFR

2013-07-01

... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

40 CFR 52.2581 - Significant deterioration of air quality.

Code of Federal Regulations, 2012 CFR

2012-07-01

... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

40 CFR 52.2581 - Significant deterioration of air quality.

Code of Federal Regulations, 2014 CFR

2014-07-01

... quality. 52.2581 Section 52.2581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Significant deterioration of air quality. (a)-(c) [Reserved] (d) The requirements of sections 160 through 165... provisions for prevention of significant deterioration of air quality at 40 CFR 52.21 are applicable to the...

Energy Performance and Optimal Control of Air-conditioned Buildings Integrated with Phase Change Materials

NASA Astrophysics Data System (ADS)

Zhu, Na

This thesis presents an overview of the previous research work on dynamic characteristics and energy performance of buildings due to the integration of PCMs. The research work on dynamic characteristics and energy performance of buildings using PCMs both with and without air-conditioning is reviewed. Since the particular interest in using PCMs for free cooling and peak load shifting, specific research efforts on both subjects are reviewed separately. A simplified physical dynamic model of building structures integrated with SSPCM (shaped-stabilized phase change material) is developed and validated in this study. The simplified physical model represents the wall by 3 resistances and 2 capacitances and the PCM layer by 4 resistances and 2 capacitances respectively while the key issue is the parameter identification of the model. This thesis also presents the studies on the thermodynamic characteristics of buildings enhanced by PCM and on the investigation of the impacts of PCM on the building cooling load and peak cooling demand at different climates and seasons as well as the optimal operation and control strategies to reduce the energy consumption and energy cost by reducing the air-conditioning energy consumption and peak load. An office building floor with typical variable air volume (VAV) air-conditioning system is used and simulated as the reference building in the comparison study. The envelopes of the studied building are further enhanced by integrating the PCM layers. The building system is tested in two selected cities of typical climates in China including Hong Kong and Beijing. The cold charge and discharge processes, the operation and control strategies of night ventilation and the air temperature set-point reset strategy for minimizing the energy consumption and electricity cost are studied. This thesis presents the simulation test platform, the test results on the cold storage and discharge processes, the air-conditioning energy consumption and demand

Greenhouse Gas Reporting Requirements Related to Stationary Refrigeration and Air Conditioning

EPA Pesticide Factsheets

Provides links to information about parts of the 2009 Mandatory Reporting of Greenhouse Gases Rule that are relevant to owners and importers of stationary refrigeration and air-conditioning equipment.

Development of a hardware-based AC microgrid for AC stability assessment

NASA Astrophysics Data System (ADS)

Swanson, Robert R.

As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.

The vestibular evoked myogenic potential (VEMP): air- versus bone-conducted stimuli.

PubMed

McNerney, Kathleen M; Burkard, Robert F

2011-01-01

Several studies have evaluated the effects of different stimulus and recording parameters on the cervical vestibular evoked myogenic potential (cVEMP); however, it is difficult to directly compare these studies as they have all used different recording methods, different sternocleidomastoid (SCM) muscle contraction/electromyography monitoring methods, and different stimulus parameters. : This study made a direct comparison of the cVEMP in response to air-conducted (AC) and bone-conducted (BC) stimuli in the same subjects, using the same stimulus/recording/electromyography monitoring methods. We found that the input/output (I/O) functions were more linear in response to AC stimuli, whereas cVEMPs in response to BC stimuli began to saturate at the highest level. In addition, cVEMP threshold was obtained at a lower stimulus level (i.e., at a lower sensation level) in response to BC stimuli as compared with AC stimuli, and cVEMPs in response to BC stimuli were larger than cVEMPs in response to AC stimuli, which is in agreement with what has been found in previous studies. In addition, this was one of the few studies to evaluate the repeatability of the cVEMP in response to BC stimuli. Interestingly, we found that cVEMP latency in response to BC stimuli was, in most cases, less variable than cVEMP latency obtained in response to AC stimuli, whereas the reverse was true for cVEMP amplitude. We also found that BC masking presented to the forehead affected response amplitude of the AC cVEMP regardless of the specific SCM muscle contraction/toneburst presentation condition. In addition, we found that the ratio of amplitude reduction was greater in the binaural stimulation/bilateral SCM muscle contraction condition as compared with the monaural stimulation/bilateral SCM muscle contraction condition. The present experiment provided a direct comparison of the cVEMP in response to AC versus BC 500 Hz short-duration toneburst stimuli in the same subjects. The results of the

PHASE I PILOT AIR CONVEYANCE SYSTEM DESIGN, CLEANING, AND CHARACTERIZATION

EPA Science Inventory

The report gives results of a project to develop and refine surface and airborne contamination
measurement techniques that can be used to evaluate air conveyance system (ACS) cleaning.
(NOTE: ACS cleaning is advertized to homeowners as a service having a number of benefits...

The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

NASA Astrophysics Data System (ADS)

Zheng, Dianfeng

2016-11-01

Ignition is a key system in pulse detonation engines (PDE). As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current (AC) driven low-temperature plasma using dielectric barrier discharge (DBD) is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter, and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma. supported by National Natural Science Foundation of China (No. 51176001)

Building Component Maintenance and Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems

DTIC Science & Technology

1991-05-01

Building Component Maintenance and Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems by Edgar S. Neely Robert D. Neathammer...Repair Data Base: Heating, Ventilating, and Air Conditioning (HVAC) Systems RDTE dated 1980EIMB 1984 - 1989 6. AUTHOR(S) Edgar S. Neely, Robert D...Laboratory (USACERL). The Principal Investigators were Dr. Edgar Neely and Mr. Robert Neathammer (USACERL-FS). The primary contractor for much of the

ac aging and space-charge characteristics in low-density polyethylene polymeric insulation

NASA Astrophysics Data System (ADS)

Chen, G.; Fu, M.; Liu, X. Z.; Zhong, L. S.

2005-04-01

In the present work efforts have been made to investigate the influence of ac aging on space-charge dynamics in low-density polyethylene (LDPE). LDPE films with 200 μm were aged under various electric stress levels at 50 Hz for various times at ambient temperature. Space-charge dynamics in the samples after aging were monitored using the pulsed electroacoustic technique. It has been revealed that the space charge under ac aging conditions is related to the level of the applied field, duration of the voltage application, as well as the electrode materials. By comparing with the results of unaged sample the results from aged sample provide a direct evidence of changing trapping characteristics after ac aging. Negative space charge is present in the bulk of the material and the total amount of charge increases with the aging time. The amount of charge increases with the applied field. Charge decay test indicates that the charges are captured in deep traps. These deep traps are believed to form during the aging and related to change caused by injected charge. By using different electrode materials such as gold, brass alloy, and polyethylene loaded with carbon black, it was found that the electrode has an important role in the formation of charge, hence subsequent changes caused by charge. The charge dynamics of the aged samples under dc bias differ from the sample without ac aging, indicating changes brought in by ac aging. Chemical analysis by Fourier transform infrared spectroscope and Raman microscope reveals no detectable chemical changes taken place in the bulk of the material after ac aging. Finally, the consequence of the accumulation of space charge under ac conditions on the lifetime of the material has been discussed. The presence of deeply trapped space charge leads to an electric stress enhancement which may shorten the lifetime of the insulation system.

Air Force Journal of Logsitics. Volume 31, Number 3, Fall 2007

DTIC Science & Technology

2007-01-01

of thc i ted .Sta’s (of should be worked in concert with the Air Force Global Logistics America, Washington, DC: Giovernment Printing Office, 2004, 7...operations. With airbase support being operational development FFG. in nature , it should not be confused with support as defined under 0 CSG is the...Australia. FCS Article Acronyms is a fundamental enabler for ADF and RAAF air operations, similar ACS - Agile Combat Support in nature to the way ACS

Airborne irritant contact dermatitis due to synthetic fibres from an air-conditioning filter.

PubMed

Patiwael, Jiska A; Wintzen, Marjolein; Rustemeyer, Thomas; Bruynzeel, Derk P

2005-03-01

We describe 8 cases of occupational airborne irritant contact dermatitis in intensive care unit (ICU) employees caused by synthetic (polypropylene and polyethylene) fibres from an air-conditioning filter. Not until a workplace investigation was conducted, was it possible to clarify the unusual sequence of events. High filter pressure in the intensive care air-conditioning system, maintained to establish an outward airflow and prevent microorganisms from entering the ward, probably caused fibres from the filter to become airborne. Upon contact with air-exposed skin, fibres subsequently provoked skin irritation. Test periods in the ICU with varying filter pressures, in an attempt to improve environmental conditions, led to even higher filter pressure levels and more complaints. The sometimes-very-low humidity might have contributed to development of skin irritation. The fact that most patients recovered quickly after treatment with emollients and changing the filters made it most likely that the airborne dermatitis was of an irritant nature.

Development and Analysis of Desiccant Enhanced Evaporative Air Conditioner Prototype

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozubal, E.; Woods, J.; Judkoff, R.

2012-04-01

This report documents the design of a desiccant enhanced evaporative air conditioner (DEVAP AC) prototype and the testing to prove its performance. Previous numerical modeling and building energy simulations indicate a DEVAP AC can save significant energy compared to a conventional vapor compression AC (Kozubal et al. 2011). The purposes of this research were to build DEVAP prototypes, test them to validate the numerical model, and identify potential commercialization barriers.

Correction of Temperatures of Air-Cooled Engine Cylinders for Variation in Engine and Cooling Conditions

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Pinkel, Benjamin; Ellerbrock, Herman H , Jr

1939-01-01

Factors are obtained from semiempirical equations for correcting engine-cylinder temperatures for variation in important engine and cooling conditions. The variation of engine temperatures with atmospheric temperature is treated in detail, and correction factors are obtained for various flight and test conditions, such as climb at constant indicated air speed, level flight, ground running, take-off, constant speed of cooling air, and constant mass flow of cooling air. Seven conventional air-cooled engine cylinders enclosed in jackets and cooled by a blower were tested to determine the effect of cooling-air temperature and carburetor-air temperature on cylinder temperatures. The cooling air temperature was varied from approximately 80 degrees F. to 230 degrees F. and the carburetor-air temperature from approximately 40 degrees F. to 160 degrees F. Tests were made over a large range of engine speeds, brake mean effective pressures, and pressure drops across the cylinder. The correction factors obtained experimentally are compared with those obtained from the semiempirical equations and a fair agreement is noted.

Transitioning to Low-GWP Alternatives in Motor Vehicle Air Conditioning Systems

EPA Pesticide Factsheets

This fact sheet provides information on low-GWP alternatives in newly manufactured motor vehicle air conditioning systems. It discusses HFC alternatives, market trends, challenges to market entry for alternatives, and potential solutions.

Heating, Ventilation, Air-conditioning, and Refrigeration. Ohio's Competency Analysis Profile.

ERIC Educational Resources Information Center

Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

Developed through a modified DACUM (Developing a Curriculum) process involving business, industry, labor, and community agency representatives in Ohio, this document is a comprehensive and verified employer competency profile for heating, ventilation, air conditioning, and refrigeration occupations. The list contains units (with and without…

Performance trends of rehabilitated AC pavements

DOT National Transportation Integrated Search

2000-10-01

The General Pavement Study (GPS) 6 experiment, "AC Overlay of AC Pavements," involves pavement test sections where an asphalt concrete (AC) overlay was placed on an existing AC pavement. This TechBrief summarizes the results of a study of the GPS-6 e...

MODELING THE AMBIENT CONDITION EFFECTS OF AN AIR-COOLED NATURAL CIRCULATION SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Rui; Lisowski, Darius D.; Bucknor, Matthew

The Reactor Cavity Cooling System (RCCS) is a passive safety concept under consideration for the overall safety strategy of advanced reactors such as the High Temperature Gas-Cooled Reactor (HTGR). One such variant, air-cooled RCCS, uses natural convection to drive the flow of air from outside the reactor building to remove decay heat during normal operation and accident scenarios. The Natural convection Shutdown heat removal Test Facility (NSTF) at Argonne National Laboratory (“Argonne”) is a half-scale model of the primary features of one conceptual air-cooled RCCS design. The facility was constructed to carry out highly instrumented experiments to study the performancemore » of the RCCS concept for reactor decay heat removal that relies on natural convection cooling. Parallel modeling and simulation efforts were performed to support the design, operation, and analysis of the natural convection system. Throughout the testing program, strong influences of ambient conditions were observed in the experimental data when baseline tests were repeated under the same test procedures. Thus, significant analysis efforts were devoted to gaining a better understanding of these influences and the subsequent response of the NSTF to ambient conditions. It was determined that air humidity had negligible impacts on NSTF system performance and therefore did not warrant consideration in the models. However, temperature differences between the building exterior and interior air, along with the outside wind speed, were shown to be dominant factors. Combining the stack and wind effects together, an empirical model was developed based on theoretical considerations and using experimental data to correlate zero-power system flow rates with ambient meteorological conditions. Some coefficients in the model were obtained based on best fitting the experimental data. The predictive capability of the empirical model was demonstrated by applying it to the new set of experimental data. The

Development of software to improve AC power quality on large spacecraft

NASA Technical Reports Server (NTRS)

Kraft, L. Alan

1991-01-01

To insure the reliability of a 20 kHz, alternating current (AC) power system on spacecraft, it is essential to analyze its behavior under many adverse operating conditions. Some of these conditions include overloads, short circuits, switching surges, and harmonic distortions. Harmonic distortions can become a serious problem. It can cause malfunctions in equipment that the power system is supplying, and, during distortions such as voltage resonance, it can cause equipment and insulation failures due to the extreme peak voltages. To address the harmonic distortion issue, work was begun under the 1990 NASA-ASEE Summer Faculty Fellowship Program. Software, originally developed by EPRI, called HARMFLO, a power flow program capable of analyzing harmonic conditions on three phase, balanced, 60 Hz AC power systems, was modified to analyze single phase, 20 kHz, AC power systems. Since almost all of the equipment used on spacecraft power systems is electrically different from equipment used on terrestrial power systems, it was also necessary to develop mathematical models for the equipment to be used on the spacecraft. The modelling was also started under the same fellowship work period. Details of the modifications and models completed during the 1990 NASA-ASEE Summer Faculty Fellowship Program can be found in a project report. As a continuation of the work to develop a complete package necessary for the full analysis of spacecraft AC power system behavior, deployment work has continued through NASA Grant NAG3-1254. This report details the work covered by the above mentioned grant.

CFD study on the effects of boundary conditions on air flow through an air-cooled condenser

NASA Astrophysics Data System (ADS)

Sumara, Zdeněk; Šochman, Michal

2018-06-01

This study focuses on the effects of boundary conditions on effectiveness of an air-cooled condenser (ACC). Heat duty of ACC is very often calculated for ideal uniform velocity field which does not correspond to reality. Therefore, this study studies the effect of wind and different landscapes on air flow through ACC. For this study software OpenFOAM was used and the flow was simulated with the use of RANS equations. For verification of numerical setup a model of one ACC cell with dimensions of platform 1.5×1.5 [m] was used. In this experiment static pressures behind fan and air flows through a model of surface of condenser for different rpm of fan were measured. In OpenFOAM software a virtual clone of this experiment was built and different meshes, turbulent models and numerical schemes were tested. After tuning up numerical setup virtual model of real ACC system was built. Influence of wind, landscape and height of ACC on air flow through ACC has been investigated.

Transitioning to Low-GWP Alternatives in Residential and Commercial Air Conditioning

EPA Pesticide Factsheets

This fact sheet provides information on low-GWP alternatives in newly manufactured residential and commercial air conditioning systems. It discusses HFC alternatives, market trends, challenges to market entry for alternatives, and potential solutions.

Estimating BrAC from transdermal alcohol concentration data using the BrAC estimator software program.

PubMed

Luczak, Susan E; Rosen, I Gary

2014-08-01

Transdermal alcohol sensor (TAS) devices have the potential to allow researchers and clinicians to unobtrusively collect naturalistic drinking data for weeks at a time, but the transdermal alcohol concentration (TAC) data these devices produce do not consistently correspond with breath alcohol concentration (BrAC) data. We present and test the BrAC Estimator software, a program designed to produce individualized estimates of BrAC from TAC data by fitting mathematical models to a specific person wearing a specific TAS device. Two TAS devices were worn simultaneously by 1 participant for 18 days. The trial began with a laboratory alcohol session to calibrate the model and was followed by a field trial with 10 drinking episodes. Model parameter estimates and fit indices were compared across drinking episodes to examine the calibration phase of the software. Software-generated estimates of peak BrAC, time of peak BrAC, and area under the BrAC curve were compared with breath analyzer data to examine the estimation phase of the software. In this single-subject design with breath analyzer peak BrAC scores ranging from 0.013 to 0.057, the software created consistent models for the 2 TAS devices, despite differences in raw TAC data, and was able to compensate for the attenuation of peak BrAC and latency of the time of peak BrAC that are typically observed in TAC data. This software program represents an important initial step for making it possible for non mathematician researchers and clinicians to obtain estimates of BrAC from TAC data in naturalistic drinking environments. Future research with more participants and greater variation in alcohol consumption levels and patterns, as well as examination of gain scheduling calibration procedures and nonlinear models of diffusion, will help to determine how precise these software models can become. Copyright © 2014 by the Research Society on Alcoholism.

[Air conducted ocular VEMP: II. First clinical investigations].

PubMed

Walther, L E; Schaaf, H; Sommer, D; Hörmann, K

2011-10-01

Vestibular-evoked myogenic potentials (VEMP) are widely used to assess vestibular function. Air conducted (AC) cervical VEMP (cVEMP) reflect sacculus and inferior vestibular nerve function. Ocular VEMP (oVEMP) however has been hardly examined up to now. In recent studies it has been assumed that AC oVEMP probably reflects superior vestibular nerve function. The aim of this pilot study was to evaluate clinical application of the AC oVEMP. AC oVEMP were recorded in patients with peripheral vestibular disorders (n=21). In addition thermal irritation and head impulse test were performed and AC cVEMP were recorded. For intense AC-sound stimulation tone bursts (500 Hz) with 100 dB nHL were used. In peripheral vestibular disorders AC oVEMP and AC cVEMP could be classified into: • type 1 (inferior vestibular neuritis) with loss of AC oVEMP but normal AC cVEMP, • type 2, probable type of superior vestibular neuritis, showing present AC cVEMP but loss of AC oVEMP, • type 3, probable complete vestibular neuritis, without AC oVEMP and AC cVEMP. AC oVEMP may be used as an appropriate test for clinical investigation in patients with vestibular disorders. AC oVEMP is an additional, essential test for assessing otolith function beside AC cVEMP. Further vestibular test are necessary for precise clinical interpretation. © Georg Thieme Verlag KG Stuttgart · New York.

The application of condensate water as an additional cooling media intermittently in condenser of a split air conditioning

NASA Astrophysics Data System (ADS)

Ardita, I. N.; Subagia, I. W. A.

2018-01-01

The condensate water produced by indoor a split air conditioning is usually not utilized and thrown away into the environment. The result of measurement shows that the temperature of condensate water produced by split air conditioning is quite low, that is 19-22 °C at the rate of 16-20 mL / min and it has PH balance. Under such conditions, Air Condensate produced by split air conditioning should still be recovered as an additional cooling medium on the condenser. This research will re-investigate the use of condensate water as an intermittent additional cooling of the condenser to increase the cooling capacity and performance of the air conditioning system. This research is done by experimental method whose implementation includes; designing and manufacturing of experimental equipment, mounting measuring tools, experimental data retrieval, data processing and yield analysis. The experimental results show that the use of condensate water as an intermittent additional cooling medium on split air conditioning condenser can increase the refrigeration effect about 2%, cooling capacity about 4% and 7% of COP system. Experimental results also show a decrease in power consumption in the system compressor about 3%

Reduction of Energy Consumption for Air Conditioning While Maintaining Acceptable Human Comfort.

DTIC Science & Technology

1988-04-01

Fanger, 1972). It is not always possible, or, practical, to obtain optimi thermal comfort conditions. Therefore Frofessor Fanger devised an index to...understand the complex interaction of the six key variables that affect human comfort. Thermal comfort is not exclusively a function of air temperature... Thermal comfort also depends on five other, less obvious, parameters: mean radiant temperature, relative air velocity, humidity, activity level, and

Statistical modeling of urban air temperature distributions under different synoptic conditions

NASA Astrophysics Data System (ADS)

Beck, Christoph; Breitner, Susanne; Cyrys, Josef; Hald, Cornelius; Hartz, Uwe; Jacobeit, Jucundus; Richter, Katja; Schneider, Alexandra; Wolf, Kathrin

2015-04-01

Within urban areas air temperature may vary distinctly between different locations. These intra-urban air temperature variations partly reach magnitudes that are relevant with respect to human thermal comfort. Therefore and furthermore taking into account potential interrelations with other health related environmental factors (e.g. air quality) it is important to estimate spatial patterns of intra-urban air temperature distributions that may be incorporated into urban planning processes. In this contribution we present an approach to estimate spatial temperature distributions in the urban area of Augsburg (Germany) by means of statistical modeling. At 36 locations in the urban area of Augsburg air temperatures are measured with high temporal resolution (4 min.) since December 2012. These 36 locations represent different typical urban land use characteristics in terms of varying percentage coverages of different land cover categories (e.g. impervious, built-up, vegetated). Percentage coverages of these land cover categories have been extracted from different sources (Open Street Map, European Urban Atlas, Urban Morphological Zones) for regular grids of varying size (50, 100, 200 meter horizonal resolution) for the urban area of Augsburg. It is well known from numerous studies that land use characteristics have a distinct influence on air temperature and as well other climatic variables at a certain location. Therefore air temperatures at the 36 locations are modeled utilizing land use characteristics (percentage coverages of land cover categories) as predictor variables in Stepwise Multiple Regression models and in Random Forest based model approaches. After model evaluation via cross-validation appropriate statistical models are applied to gridded land use data to derive spatial urban air temperature distributions. Varying models are tested and applied for different seasons and times of the day and also for different synoptic conditions (e.g. clear and calm

40 CFR 86.162-03 - Approval of alternative air conditioning test simulations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... conditioning test simulations. 86.162-03 Section 86.162-03 Protection of Environment ENVIRONMENTAL PROTECTION... Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles; Test Procedures § 86.162-03 Approval of alternative air conditioning test simulations. (a) Upon petition from a manufacturer or upon the Agency's own...

[Influence of industrial pollution of ambient air on health of workers engaged into open air activities in cold conditions].

PubMed

Chashchin, V P; Siurin, S A; Gudkov, A B; Popova, O N; Voronin, A Iu

2014-01-01

The article presents the results of a study on assessment of occupational exposure to air pollutants and related health effects in3792 outdoor workers engaged in operations performed in the vicinity of non-ferrous metallurgical facilities in Far North. Findings are that during cold season repeated climate and weather conditions are associated with higher level of chemical hazards and dust in surface air. At the air temperature below -17 degrees C, maximal single concentrations of major pollutants can exceed MAC up to 10 times. With that, transitory disablement morbidity parameters and occupational accidents frequency increase significantly. The workers with long exposure to cooling meteorological factors and air pollution demonstrate significantly increased prevalence of respiratory and circulatory diseases, despite relatively low levels of sculpture dioxide and dust in the air, not exceeding the occupational exposure limits. It has been concluded that severe cold is to be considered asa factor increasing occupational risk at air polluted outdoor worksites dueto more intense air pollution, higher traumatism risk and lower efficiency of filter antidust masks respiratory PPE and due to modification of the toxic effects.

Improved Tribological Performance of Amorphous Carbon (a-C) Coating by ZrO₂ Nanoparticles.

PubMed

Tang, Jinzhu; Ding, Qi; Zhang, Songwei; Wu, Guizhi; Hu, Litian

2016-09-22

Nanomaterials, such as Graphene, h-BN nanoparticles and MoS₂ nanotubes, have shown their ability in improving the tribological performance of amorphous carbon (a-C) coatings. In the current study, the effectiveness of ZrO₂ nanoparticles (ZrO₂-NPs) in lubricating the self-mated nonhydrogenated a-C contacts was investigated in boundary lubrication regime. The results showed that 13% less friction and 50% less wear compared to the base oil were achieved by employing ZrO₂-NPs in the base oil in self-mated a-C contacts. Via analyzing the ZrO₂-NPs and the worn a-C surface after tests, it was found that the improved lubrication by ZrO₂-NPs was based on "polishing effects", which is a new phenomenon observed between a-C and nanoparticles. Under the "polishing effect", micro-plateaus with extremely smooth surface and uniform height were produced on the analyzed a-C surface. The resulting topography of the a-C coating is suitable for ZrO₂-NPs to act as nano-bearings between rubbing surfaces. Especially, the ZrO₂-NPs exhibited excellent mechanical and chemical stability, even under the severe service condition, suggesting that the combination of nonhydrogenated a-C coating with ZrO₂-NPs is an effective, long lasting and environment-friendly lubrication solution.

AC/RC Force Integration

DTIC Science & Technology

1991-05-01

ib qeocie. Thki document may not be rdeaed for open publicado. untit hu been deared by die appropriate military seavice or a veunent agency. AC /RC...A N/A N/A 11. TITLE (Include Security Classification) AC /RC Force Structure Integraticn 12. PERSONAL AUTHOR(S) Russell A. Eggers 13a. TYPE OF REPORT... AC ) and Reserve Components (RC) Force Integration is critical in today’s Total Army. The Army of soldiers, Active and Reserve, exists to play a key

24 CFR 3280.813 - Outdoor outlets, fixtures, air-conditioning equipment, etc.

Code of Federal Regulations, 2013 CFR

2013-04-01

... the home or located under roof extensions or similarly protected locations, they may be listed for use..., adjacent to the outlet, a metal tag which reads: This Connection Is for Air Conditioning Equipment Rated at...

24 CFR 3280.813 - Outdoor outlets, fixtures, air-conditioning equipment, etc.

Code of Federal Regulations, 2012 CFR

2012-04-01

... the home or located under roof extensions or similarly protected locations, they may be listed for use..., adjacent to the outlet, a metal tag which reads: This Connection Is for Air Conditioning Equipment Rated at...

24 CFR 3280.813 - Outdoor outlets, fixtures, air-conditioning equipment, etc.

Code of Federal Regulations, 2011 CFR

2011-04-01

... the home or located under roof extensions or similarly protected locations, they may be listed for use..., adjacent to the outlet, a metal tag which reads: This Connection Is for Air Conditioning Equipment Rated at...

[Effectiveness of the maintenance operations on the air conditioning systems of a university building in relation to the microbiological quality of the air indoor].

PubMed

De Filippis, Patrizia; Spinaci, Anna; Coia, Maura; Maggi, Oriana; Panà, Augusto

2003-01-01

The microbiological quality of the air indoor is influenced from various factors and one of the most important is represented from the maintenance of the conditioning systems. In this study it has been estimated the effectiveness of an intervention of cleaning and maintenance on the systems of conditioning of an university building executing sampling before and after such intervention. The two results were confronted and it is observed as the maintenance of the air conditioners has influenced on the quality of the air indoor.

Characterizing fiber-reinforced composite structures using AC-impedance spectroscopy (AC-IS)

NASA Astrophysics Data System (ADS)

Woo, Leta Y.

Property enhancement in composites depends largely on the reinforcement. For fiber-reinforced composites, the distribution of fibers is crucial in determining the electrical and mechanical performance. Image analysis methods for characterization can be time-consuming and/or destructive. This work explores the capability of AC-impedance spectroscopy (AC-IS), an electrical measurement technique, to serve as a rapid, non-destructive tool for characterizing composite microstructure. The composite requirements include a filler that is electrically conducting or semi-conducting with higher conductivity than the matrix, and a high-impedance interface or coating between the filler and the matrix. To establish an AC-IS characterization method, cement-matrix composites with steel reinforcement were employed as both a technologically important and a model system to investigate how fibers affect the electrical response. Beginning with spherical particulates and then fibers, composites were examined using composite theory and an "intrinsic conductivity" approach. The intrinsic conductivity approach applies to composites with low volume fractions of fibers (i.e., in the dilute regime) and relates how the composite conductivity varies relative to the matrix as a function of volume fraction. A universal equivalent circuit model was created to understand the AC-IS response of composites based on the geometry and volume fraction of the filler. Deviation from predicted behavior was assessed using a developed f-function, which quantifies how fibers contribute to the overall electrical response of the composite. Using the f-function, an AC-IS method for investigating fiber dispersion was established to characterize alignment, settling/segregation, and aggregation. Alignment was investigated using measurements made in three directions. A point-probe technique characterized settling and/or large-scale inhomogeneous mixing in samples. Aggregation was quantified using a "dispersion factor

Heating and Air Conditioning Specialist. Teacher Edition. Automotive Service Series.

ERIC Educational Resources Information Center

Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This instructor's guide contains materials for teaching the heating and air conditioning specialist component of a competency-based instructional program for students preparing for employment in the automotive service trade. It is based on the National Institute of Automotive Service Excellence task lists. The six instructional units presented…

Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

NASA Technical Reports Server (NTRS)

Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

2008-01-01

Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

Experimental performance study of a proposed desiccant based air conditioning system.

PubMed

Bassuoni, M M

2014-01-01

An experimental investigation on the performance of a proposed hybrid desiccant based air conditioning system referred as HDBAC is introduced in this paper. HDBAC is mainly consisted of a liquid desiccant dehumidification unit integrated with a vapor compression system (VCS). The VCS unit has a cooling capacity of 5.27 kW and uses 134a as refrigerant. Calcium chloride (CaCl2) solution is used as the working desiccant material. HDBAC system is used to serve low sensible heat factor applications. The effect of different parameters such as, process air flow rate, desiccant solution flow rate, evaporator box and condenser box solution temperatures, strong solution concentration and regeneration temperature on the performance of the system is studied. The performance of the system is evaluated using some parameters such as: the coefficient of performance (COPa), specific moisture removal and energy saving percentage. A remarkable increase of about 54% in the coefficient of performance of the proposed system over VCS with reheat is achieved. A maximum overall energy saving of about 46% is observed which emphasizes the use of the proposed system as an energy efficient air conditioning system.

Experimental performance study of a proposed desiccant based air conditioning system

PubMed Central

Bassuoni, M.M.

2013-01-01

An experimental investigation on the performance of a proposed hybrid desiccant based air conditioning system referred as HDBAC is introduced in this paper. HDBAC is mainly consisted of a liquid desiccant dehumidification unit integrated with a vapor compression system (VCS). The VCS unit has a cooling capacity of 5.27 kW and uses 134a as refrigerant. Calcium chloride (CaCl2) solution is used as the working desiccant material. HDBAC system is used to serve low sensible heat factor applications. The effect of different parameters such as, process air flow rate, desiccant solution flow rate, evaporator box and condenser box solution temperatures, strong solution concentration and regeneration temperature on the performance of the system is studied. The performance of the system is evaluated using some parameters such as: the coefficient of performance (COPa), specific moisture removal and energy saving percentage. A remarkable increase of about 54% in the coefficient of performance of the proposed system over VCS with reheat is achieved. A maximum overall energy saving of about 46% is observed which emphasizes the use of the proposed system as an energy efficient air conditioning system. PMID:25685475

Careers for the 70's in Heating and Air Conditioning

ERIC Educational Resources Information Center

Toner, James P.

1974-01-01

In a trade encompassing all others in construction, installation foremen for heating/air conditioning firms spend a varied day (repairing a water heater, overseeing installation crews). Decision-makers who must think while using their hands, they rely heavily on preparation in math, mechanical drawing, blueprint reading, physics, and electicity.…

Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

NASA Astrophysics Data System (ADS)

Agrawal, Tanmay; Varun; Kumar, Anoop

2015-10-01

Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

Heavy metal contamination in an urban stream fed by contaminated air-conditioning and stormwater discharges.

PubMed

O'Sullivan, Aisling; Wicke, Daniel; Cochrane, Tom

2012-03-01

Urban waterways are impacted by diffuse stormwater runoff, yet other discharges can unintentionally contaminate them. The Okeover stream in Christchurch, New Zealand, receives air-conditioning discharge, while its ephemeral reach relies on untreated stormwater flow. Despite rehabilitation efforts, the ecosystem is still highly disturbed. It was assumed that stormwater was the sole contamination source to the stream although water quality data were sparse. We therefore investigated its water and sediment quality and compared the data with appropriate ecotoxicological thresholds from all water sources. Concentrations of metals (Zn, Cu and Pb) in stream baseflow, stormwater runoff, air-conditioning discharge and stream-bed sediments were quantified along with flow regimes to ascertain annual contaminant loads. Metals were analysed by ICP-MS following accredited techniques. Zn, Cu and Pb concentrations from stormflow exceeded relevant guidelines for the protection of 90% of aquatic species by 18-, 9- and 5-fold, respectively, suggesting substantial ecotoxicity potential. Sporadic copper (Cu) inputs from roof runoff exceeded these levels up to 3,200-fold at >4,000 μg L⁻¹ while Cu in baseflow from air-conditioning inputs exceeded them 5.4-fold. There was an 11-fold greater annual Cu load to the stream from air-conditioning discharge compared to stormwater runoff. Most Zn and Cu were dissolved species possibly enhancing metal bioavailability. Elevated metal concentrations were also found throughout the stream sediments. Environmental investigations revealed unsuspected contamination from air-conditioning discharge that contributed greater Cu annual loads to an urban stream compared to stormwater inputs. This discovery helped reassess treatment strategies for regaining ecological integrity in the ecosystem.

Waking the sleeping giant: Introducing new heat exchanger technology into the residential air-conditioning marketplace

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapp, T.; Voss, M.; Stephens, C.

1998-07-01

The Air Conditioning Industry has made tremendous strides in improvements to the energy efficiency and reliability of its product offerings over the past 40 years. These improvement can be attributed to enhancements of components, optimization of the energy cycle, and modernized and refined manufacturing techniques. During this same period, energy consumption for space cooling has grown significantly. In January of 1992, the minimum efficiency requirement for central air conditioning equipment was raised to 10 SEER. This efficiency level is likely to increase further under the auspices of the National Appliance Energy Conservation Act (NAECA). A new type of heat exchangermore » was developed for air conditioning equipment by Modine Manufacturing Company in the early 1990's. Despite significant advantages in terms of energy efficiency, dehumidification, durability, and refrigerant charge there has been little interest expressed by the air conditioning industry. A cooperative effort between Modine, various utilities, and several state energy offices has been organized to test and demonstrate the viability of this heat exchanger design throughout the nation. This paper will review the fundamentals of heat exchanger design and document this simple, yet novel technology. These experiences involving equipment retrofits have been documented with respect to the performance potential of air conditioning system constructed with PF{trademark} Heat Exchangers (generically referred to as microchannel heat exchangers) from both an energy efficiency as well as a comfort perspective. The paper will also detail the current plan to introduce 16 to 24 systems into an extended field test throughout the US which commenced in the Fall of 1997.« less

Air- ice-snow interaction in the Northern Hemisphere under different stability conditions

NASA Astrophysics Data System (ADS)

Repina, Irina; Chechin, Dmitry; Artamonov, Arseny

2013-04-01

The traditional parameterizations of the atmospheric boundary layer are based on similarity theory and the coefficients of turbulent transfer, describing the atmospheric-surface interaction and the diffusion of impurities in the operational models of air pollution, weather forecasting and climate change. Major drawbacks of these parameterizations is that they are not applicable for the extreme conditions of stratification and currents over complex surfaces (such as sea ice, marginal ice zone or stormy sea). These problem could not be overcome within the framework of classical theory, i.e, by rectifying similarity functions or through the introduction of amendments to the traditional turbulent closure schemes. Lack of knowledge on the structure of the surface air layer and the exchange of momentum, heat and moisture between the rippling water surface and the atmosphere at different atmospheric stratifications is at present the major obstacle which impede proper functioning of the operational global and regional weather prediction models and expert models of climate and climate change. This is especially important for the polar regions, where in winter time the development of strong stable boundary layer in the presence of polynyas and leads usually occur. Experimental studies of atmosphere-ice-snow interaction under different stability conditions are presented. Strong stable and unstable conditions are discussed. Parametrizations of turbulent heat and gas exchange at the atmosphere ocean interface are developed. The dependence of the exchange coefficients and aerodynamic roughness on the atmospheric stratification over the snow and ice surface is experimentally confirmed. The drag coefficient is reduced with increasing stability. The behavior of the roughness parameter is simple. This result was obtained in the Arctic from the measurements over hummocked surface. The value of the roughness in the Arctic is much less than that observed over the snow in the middle and

The ACS statistical analyzer

DOT National Transportation Integrated Search

2010-03-01

This document provides guidance for using the ACS Statistical Analyzer. It is an Excel-based template for users of estimates from the American Community Survey (ACS) to assess the precision of individual estimates and to compare pairs of estimates fo...

Design and implementation of an air-conditioning system with storage tank for load shifting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Y.Y.; Wu, C.J.; Liou, K.L.

1987-11-01

The experience with the design, simulation and implementation of an air-conditioning system with chilled water storage tank is presented in this paper. The system is used to shift air-conditioning load of residential and commercial buildings from on-peak to off-peak period. Demand-side load management can thus be achieved if many buildings are equipped with such storage devices. In the design of this system, a lumped-parameter circuit model is first employed to simulate the heat transfer within the air-conditioned building such that the required capacity of the storage tank can be figured out. Then, a set of desirable parameters for the temperaturemore » controller of the system are determined using the parameter plane method and the root locus method. The validity of the proposed mathematical model and design approach is verified by comparing the results obtained from field tests with those from the computer simulations. Cost-benefit analysis of the system is also discussed.« less

[Heat and moisture exchangers for conditioning of inspired air of intubated patients in intensive care. The humidification properties of passive air exchangers under clinical conditions].

PubMed

Rathgeber, J; Züchner, K; Kietzmann, D; Weyland, W

1995-04-01

Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent tracheo-bronchial or pulmonary damage resulting from dry and cold inspired gases. HME are mounted directly on the tracheal tube, where they collect a large fraction of the heat and moisture of the expired air, adding this to the subsequent inspired breath. The effective performance depends on the water-retention capacity of the HME: the amount of water added to the inspired gas cannot exceed the stored water uptake of the previous breath. This study evaluates the efficiency of four different HME under laboratory and clinical conditions using a new moisture-measuring device. METHODS. In a first step, the absolute efficiency of four different HME (DAR Hygrobac, Gibeck Humid-Vent 2P, Pall BB 22-15 T, and Pall BB 100) was evaluated using a lung model simulating physiological heat and humidity conditions of the upper airways. The model was ventilated with tidal volumes of 500, 1,000, and 1,500 ml and different flow rates. The water content of the ventilated air was determined between tracheal tube and HME using a new high-resolution humidity meter and compared with the absolute water loss of the exhaled air at the gas outlet of a Siemens Servo C ventilator measured with a dew-point hygrometer. Secondly, the moisturizing efficiency was evaluated under clinical conditions in an intensive care unit with 25 intubated patients. Maintaining the ventilatory conditions for each patient, the HME were randomly changed. The humidity data were determined as described above and compared with the laboratory findings. RESULTS AND DISCUSSION. The water content at the respirator outlet is inversely equivalent to the humidity of the inspired gases and represents the water loss from the respiratory tract if the patient is ventilated with dry gases. Moisture retention and heating capacity decreased with higher volumes and higher flow rates. These data are simple to obtain without affecting the

An Analysis of the Air Conditioning, Refrigerating and Heating Occupation.

ERIC Educational Resources Information Center

Frass, Melvin R.; Krause, Marvin

The general purpose of the occupational analysis is to provide workable, basic information dealing with the many and varied duties performed in the air conditioning, refrigerating, and heating occupation. The document opens with a brief introduction followed by a job description. The bulk of the document is presented in table form. Six duties are…

Motor Transportation Technology: Automechanics. [Air Conditioning.] Block IX. A-IX.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Vocational Instructional Services.

This packet contains 13 teacher lesson plans with related student information, job sheets, and task sheets for a block of instruction on motor vehicle refrigeration (air conditioning) systems in a course on auto mechanics. Lesson plans, which are either informational or manipulative in format, take the teacher step-by-step through each lesson.…

Contribution of Atmospheric Diffusion Conditions to the Recent Improvement in Air Quality in China

PubMed Central

Wang, Xiaoyan; Wang, Kaicun; Su, Liangyuan

2016-01-01

This study analyzed hourly mass concentration observations of PM2.5 (particulate matters with diameter less than 2.5 μm) at 512 stations in China from December 2013 to May 2015. We found that the mean concentrations of PM2.5 during the winter and spring of 2015 Dec. 2014 to Feb. 2015 and Mar. 2015 to May 2015) decreased by 20% and 14% compared to the previous year, respectively. Hazardous air-quality days decreased by 11% in 2015 winter, with more frequent good to unhealthy days; and the good and moderate air-quality days in 2015 spring increased by 9% corresponding to the less occurrence of unhealthy conditions. We compared the atmospheric diffusion conditions during these two years and quantified its contribution to the improvement of air quality during the first half of 2015 over China. Our results show that during the 2015 winter and spring, 70% and 57% of the 512 stations experienced more favorable atmospheric diffusion conditions compared to those of previous year. Over central and northern China, approximately 40% of the total decrease in PM2.5 during the 2015 winter can be attributed to the favorable atmospheric diffusion conditions. The atmospheric diffusion conditions during the spring of 2015 were not as favorable as in winter; and the average contributions of the atmospheric conditions were slight. PMID:27805030

Observations of the convective plume of a lake under cold-air advective conditions

NASA Technical Reports Server (NTRS)

Bill, R. G., Jr.; Sutherland, R. A.; Bartholic, J. F.; Chen, E.

1978-01-01

Moderating effects of Lake Apopka, Florida, on downwind surface temperatures were evaluated under cold-air advective conditions. Point temperature measurements north and south of the lake and data obtained from a thermal scanner flown at 1.6 km indicate that surface temperatures directly downwind may be higher than surrounding surface temperatures by as much as 5 C under conditions of moderate winds (about 4 m/s). No substantial temperature effects were observed with surface wind speed less than 1 m/s. Fluxes of sensible and latent heat from Lake Apopka were calculated from measurements of lake temperature, net radiation, relative humidity, and air temperature above the lake. Bulk transfer coefficients and the Bowen ratio were calculated and found to be in agreement with reported data for nonadvective conditions.

Investigation of the transition of multicycle AC operation in ISTTOK under edge electrode biasing

NASA Astrophysics Data System (ADS)

Malaquias, A.; Henriques, R. B.; Silva, C.; Figueiredo, H.; Nedzelskiy, I. S.; Fernandes, H.; Sharma, R.; Plyusnin, V. V.

2017-11-01

In this paper we present recent results obtained on plasma edge electrode biasing during AC discharges. The goal is to obtain experimental evidence on a number of plasma parameters that can play a role during the AC transition on the repeatability and reproducibility of AC operation. The control of the plasma density in the quiescent phase is made just before the AC transition by means of positive edge biasing leading to a transitory improved of density (30%-40%). Gas puff experiments show that the increase of background gas pressure during discharge led to a better success of the AC transition. The experimental results indicate that the increase of density during the AC transition induced by edge biasing is followed by an electron temperature drop. The drop in electron temperature leads in most cases the formation of runaway electrons. It has been observed that the runaway population during discharge flattop depends on the interplay between gas content and plasma density and temperature. The results also confirm that the correct balance of external magnetic fields is crucial during the AC transition phase where drift electron currents are formed. The results from the heavy ion beam diagnostic show that the formation of plasma current during consecutive AC transitions is asymmetric. Numerical simulations indicate that for some particular conditions this result could be reproduced from assuming the presence of two counter-currents during AC transition.

Improving the performance of air-conditioning systems in an ASEAN (Association of South East Asian Nations) climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Busch, J.F.; Warren, M.L.

1988-09-01

This paper describes an analysis of air conditioning performance under hot and humid tropical climate conditions appropriate to the Association of South East Asian Nations (ASEAN) countries. This region, with over 280 million people, has one of the fastest economic and energy consumption growth rates in the world. The work reported here is aimed at estimating the conservation potential derived from good design and control of air conditioning systems in commercial buildings. To test the performance of different air conditioning system types and control options, whole building energy performance was simulated using DOE-2. The 5100 m/sup 2/ (50,000 ft/sup 2/)more » prototype office building module was previously used in earlier commercial building energy standards analysis for Malaysia and Singapore. In general, the weather pattern for ASEAN countries is uniform, with hot and humid air masses known as ''monsoons'' dictating the weather patterns. Since a concentration of cities occurs near the tip of the Malay peninsula, hourly temperature, humidity, and wind speed data for Kuala Lumpur was used for the analysis. Because of the absence of heating loads in ASEAN regions, we have limited air conditioning configurations to two pipe fan coil, constant volume, variable air volume, powered induction, and ceiling bypass configurations. Control strategies were varied to determine the conservation potential in both energy use and peak electric power demands. Sensitivities including fan control, pre-cooling and night ventilation, supply air temperature control, zone temperature set point, ventilation and infiltration, daylighting and internal gains, and system sizing were examined and compared with a base case which was a variable air volume system with no reheat or economizer. Comfort issues, such as over-cooling and space humidity, were also examined.« less

Slow-onset and fast-onset symptom presentations in acute coronary syndrome (ACS): new perspectives on prehospital delay in patients with ACS.

PubMed

O'Donnell, Sharon; McKee, Gabrielle; Mooney, Mary; O'Brien, Frances; Moser, Debra K

2014-04-01

Patient decision delay is the main reason why many patients fail to receive timely medical intervention for symptoms of acute coronary syndrome (ACS). This study examines the validity of slow-onset and fast-onset ACS presentations and their influence on ACS prehospital delay times. A fast-onset ACS presentation is characterized by sudden, continuous, and severe chest pain, and slow-onset ACS pertains to all other ACS presentations. Baseline data pertaining to medical profiles, prehospital delay times, and ACS symptoms were recorded for all ACS patients who participated in a large multisite randomized control trial (RCT) in Dublin, Ireland. Patients were interviewed 2-4 days after their ACS event, and data were gathered using the ACS Response to Symptom Index. Only baseline data from the RCT, N = 893 patients, were analyzed. A total of 65% (n = 577) of patients experienced slow-onset ACS presentation, whereas 35% (n = 316) experienced fast-onset ACS. Patients who experienced slow-onset ACS were significantly more likely to have longer prehospital delays than patients with fast-onset ACS (3.5 h vs. 2.0 h, respectively, t = -5.63, df 890, p < 0.001). A multivariate analysis of delay revealed that, in the presence of other known delay factors, the only independent predictors of delay were slow-onset and fast-onset ACS (β = -.096, p < 0.002) and other factors associated with patient behavior. Slow-onset ACS and fast-onset ACS presentations are associated with distinct behavioral patterns that significantly influence prehospital time frames. As such, slow-onset ACS and fast-onset ACS are legitimate ACS presentation phenomena that should be seriously considered when examining the factors associated with prehospital delay. Copyright © 2014 Elsevier Inc. All rights reserved.

Meteorological conditions are associated with physical activities performed in open-air settings

NASA Astrophysics Data System (ADS)

Suminski, Richard R.; Poston, Walker C.; Market, Patrick; Hyder, Melissa; Sara, Pyle A.

2008-01-01

Meteorological conditions (MC) are believed to modify physical activity. However, studies in this area are limited and none have looked at the associations between MC and physical activity in open-air settings. Therefore, we examined the relationships between MC and physical activities performed on sidewalks/streets and outdoor oval tracks. Observation techniques were used to count individuals walking to school, exercising on oval tracks and walking/jogging/biking on sidewalks/streets. Meteorological conditions were obtained from an Automated Surface Observing System located at a nearby airport for the same time periods physical activities were observed. On weekdays, fewer children were seen walking to school and more bicyclists were observed on sidewalks/streets as wind speed increased ( p < 0.05). Ambient and apparent temperatures were positively ( p < 0.05) and humidity and barometric pressure negatively ( p < 0.005) related to the number of individuals walking on the track. Meteorological conditions were not significantly associated with physical activities observed on weekends. Multiple linear regression analyses showed that apparent temperature (+), barometric pressure (-) and dew point (-) accounted for 58.0% of the variance in the number of walkers on the track. A significant proportion of the variance (>30%) in the number of joggers and the length of time they jogged was accounted for by apparent temperature (+) and dew point (-). We found that meteorological conditions are related to physical activity in open-air settings. The results embellish the context in which environmental-physical activity relationships should be interpreted and provide important information for researchers applying the observation method in open-air settings.

An ac electroosmosis device for the detection of bioparticles with piezoresistive microcantilever sensors

NASA Astrophysics Data System (ADS)

Arefin, Md Shamsul; Porter, Timothy L.

2012-03-01

This work reports on the behavior of piezoresistive microcantilever sensors under optimizing conditions of ac electroosmotic enhancement. Piezoresistive microcantilevers are used as sensor elements for detection of concentrated bio-particles. Without preconcentrating the samples, using ac electroosmosis, these bio-particles have been manipulated onto the piezoresistive microcantilever. A piezoresistive microcantilever senses the dimensional changes upon particle exposure as a resistance change. This paper represents the integration of ac electroosmosis with a piezoresistive micro-cantilever sensor for the detection of bio-particles. A working prototype is presented here, and the experiments are conducted on Herpes Simplex type-1 virus (HSV-1) and Escherichia Coli (E. coli) bacteria.

Piston Temperatures in an Air-Cooled Engine for Various Operating Conditions

NASA Technical Reports Server (NTRS)

Manganiello, Eugene J

1940-01-01

As part of a program for the study of piston cooling, this report presents the results of tests conducted on a single-cylinder, air-cooled, carburetor engine to determine the effect of engine operating conditions on the temperatures at five locations on the piston.

24 CFR 3280.813 - Outdoor outlets, fixtures, air-conditioning equipment, etc.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Outdoor outlets, fixtures, air-conditioning equipment, etc. 3280.813 Section 3280.813 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING...

Performance Analysis of Air-to-Water Heat Pump in Latvian Climate Conditions

NASA Astrophysics Data System (ADS)

Kazjonovs, Janis; Sipkevics, Andrejs; Jakovics, Andris; Dancigs, Andris; Bajare, Diana; Dancigs, Leonards

2014-12-01

Strategy of the European Union in efficient energy usage demands to have a higher proportion of renewable energy in the energy market. Since heat pumps are considered to be one of the most efficient heating and cooling systems, they will play an important role in the energy consumption reduction in buildings aimed to meet the target of nearly zero energy buildings set out in the EU Directive 2010/31/EU. Unfortunately, the declared heat pump Coefficient of Performance (COP) corresponds to a certain outdoor temperature (+7 °C), therefore different climate conditions, building characteristics and settings result in different COP values during the year. The aim of this research is to investigate the Seasonal Performance factor (SPF) values of air-to-water heat pump which better characterize the effectiveness of heat pump in a longer selected period of time, especially during the winter season, in different types of residential buildings in Latvian climate conditions. Latvia has four pronounced seasons of near-equal length. Winter starts in mid-December and lasts until mid-March. Latvia is characterized by cold, maritime climate (duration of the average heating period being 203 days, the average outdoor air temperature during the heating period being 0.0 °C, the coldest five-day average temperature being -20.7 °C, the average annual air temperature being +6.2 °C, the daily average relative humidity being 79 %). The first part of this research consists of operational air-towater heat pump energy performance monitoring in different residential buildings during the winter season. The second part of the research takes place under natural conditions in an experimental construction stand which is located in an urban environment in Riga, Latvia. The inner area of this test stand, where air-to-water heat pump performance is analyzed, is 9 m2. The ceiling height is 3 m, all external wall constructions (U = 0.16 W/(m2K)) have ventilated facades. To calculate SPF, the

Power conditioning system for energy sources

DOEpatents

Mazumder, Sudip K [Chicago, IL; Burra, Rajni K [Chicago, IL; Acharya, Kaustuva [Chicago, IL

2008-05-13

Apparatus for conditioning power generated by an energy source includes an inverter for converting a DC input voltage from the energy source to a square wave AC output voltage, and a converter for converting the AC output voltage from the inverter to a sine wave AC output voltage.

Effect of Intake Air Filter Condition on Light-Duty Gasoline Vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, John F; Huff, Shean P; West, Brian H

2012-01-01

Proper maintenance can help vehicles perform as designed, positively affecting fuel economy, emissions, and the overall drivability. This effort investigates the effect of one maintenance factor, intake air filter replacement, with primary focus on vehicle fuel economy, but also examining emissions and performance. Older studies, dealing with carbureted gasoline vehicles, have indicated that replacing a clogged or dirty air filter can improve vehicle fuel economy and conversely that a dirty air filter can be significantly detrimental to fuel economy. The effect of clogged air filters on the fuel economy, acceleration and emissions of five gasoline fueled vehicles is examined. Fourmore » of these were modern vehicles, featuring closed-loop control and ranging in model year from 2003 to 2007. Three vehicles were powered by naturally aspirated, port fuel injection (PFI) engines of differing size and cylinder configuration: an inline 4, a V6 and a V8. A turbocharged inline 4-cylinder gasoline direct injection (GDI) engine powered vehicle was the fourth modern gasoline vehicle tested. A vintage 1972 vehicle equipped with a carburetor (open-loop control) was also examined. Results reveal insignificant fuel economy and emissions sensitivity of modern vehicles to air filter condition, but measureable effects on the 1972 vehicle. All vehicles experienced a measured acceleration performance penalty with clogged intake air filters.« less

Microfabricated AC impedance sensor

DOEpatents

Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

2002-01-01

A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

SUMMARY OF ELECTRIC SERVICE COSTS FOR TOTALLY AIR CONDITIONED SCHOOLS PREPARED FOR HOUSTON INDEPENDENT SCHOOL DISTRICT, MAY 31, 1967.

ERIC Educational Resources Information Center

WHITESIDES, M.M.

THIS REPORT IS A COMPILATION OF DATA ON ELECTRIC AIR CONDITIONING COSTS, OPERATIONS AND MAINTENANCE. AIR CONDITIONING UNITS ARE COMPARED IN TERMS OF ELECTRIC VERSUS NON-ELECTRIC, AUTOMATIC VERSUS OPERATED, AIR COOLED VERSUS WATER COOLED, RECIPROCATING VERSUS CENTRIFUGAL COMPRESSORS, SPACE AND NOISE, REHEAT, MAINTENANCE AND ORIGINAL COST. DATA ARE…

[Study on air quality and pollution meteorology conditions of Guangzhou during the 2010 Asian games].

PubMed

Li, Ting-Yuan; Deng, Xue-Jiao; Fan, Shao-Jia; Wu, Dui; Li, Fei; Deng, Tao; Tan, Hao-Bo; Jiang, De-Hai

2012-09-01

Based on the monitoring data of NO2, O3, SO2, PM, visibility, regional air quality index (RAQI) and the atmospheric transport and diffusion data from Nov. 4, 2010 to Dec. 10, 2010 in Guangzhou area, the variations of air quality and meteorological conditions during the Guangzhou Asian Games were analyzed. It was found that, during the Asian Games, the air quality was better than the air quality before or after the Asian Games. The visibility was greater than the visibility before or after the Asian Games, while the concentrations of PM1 and PM2.5 were lower. The correlation coefficient between visibility and the concentrations of PM1, PM2.5 indicated anti-correlation relationships. Daily and hourly concentrations of NO2 and SO2 met the primary ambient air quality standards, whereas the daily concentration of PM10 and hourly concentration of O3 met the secondary ambient air quality standards. Pollutants had been well controlled during the Asian Games. The concentration of SO2 in Guangzhou was influenced by local sources and long distance transmission, while the concentration of NO2 was significantly influenced by local sources. The emissions of NO2, SO2 and PM10 surrounding Guangzhou had a trend to affect the concentrations in Guangzhou, but the situation of O3 was opposite, the relatively high concentration of O3 in Guangzhou had tendency to be transported to the surrounding areas. The pollution meteorology conditions in the period of Asian Games were better than the conditions before or after the Asian Games. The decrease in the concentrations during the Asian Games did not only benefit from the emission control by the government, but also from the good meteorological conditions.

Instructional Guide for Air Conditioning and Refrigeration. V & TECC Curriculum Guide.

ERIC Educational Resources Information Center

Duenk, Lester G.; And Others

This trade and industrial curriculum guide is intended for use in vocational programs that prepare students to enter the air conditioning/refrigeration field. The introductory section provides a statement of philosophy, objectives, block time schedule, and recommended facilities and equipment. Following the introductory section, eighteen blocks of…

[Hygienic assessment of a recirculatory combined air-conditioning extract-and-input system in office building].

PubMed

Malysheva, A G; Abramov, E G

2006-01-01

The high concentrations of lead were reveled in the air and dust of some premises and on the filters of a combined air-conditioning extract-and-input system in the high-rise office buildings located in the ecologically lead favorable environment. The dust content of lead in some premises on the first floors dust was as high as 200 mg/kg, which was more than 6 times higher than that in the soil at the highway near the office buildings. The use of new technologies and devices for cleaning and optimizing the air in the premises requires analytical studies to assess the quality of the environment, by taking into account the optimal conditions of their operation.

High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

NASA Astrophysics Data System (ADS)

Abbas, Qamar; Béguin, François

2016-06-01

We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

Air Controlman 3 and 2: Naval Rate Training Manual and Nonresident Career Course.

ERIC Educational Resources Information Center

Naval Education and Training Command, Pensacola, FL.

The Rate Training Manual is one of a series of training manuals prepared for enlisted personnel of the Navy and Naval Reserve studying for advancement in the Air Controlman (AC) rating to Air Controlman Third and Second Class. Chapter 1 discusses air controlman qualifications, the enlisted rating structure, the Air Controlman rating, references…

Effect of real-time boundary wind conditions on the air flow and pollutant dispersion in an urban street canyon—Large eddy simulations

NASA Astrophysics Data System (ADS)

Zhang, Yun-Wei; Gu, Zhao-Lin; Cheng, Yan; Lee, Shun-Cheng

2011-07-01

Air flow and pollutant dispersion characteristics in an urban street canyon are studied under the real-time boundary conditions. A new scheme for realizing real-time boundary conditions in simulations is proposed, to keep the upper boundary wind conditions consistent with the measured time series of wind data. The air flow structure and its evolution under real-time boundary wind conditions are simulated by using this new scheme. The induced effect of time series of ambient wind conditions on the flow structures inside and above the street canyon is investigated. The flow shows an obvious intermittent feature in the street canyon and the flapping of the shear layer forms near the roof layer under real-time wind conditions, resulting in the expansion or compression of the air mass in the canyon. The simulations of pollutant dispersion show that the pollutants inside and above the street canyon are transported by different dispersion mechanisms, relying on the time series of air flow structures. Large scale air movements in the processes of the air mass expansion or compression in the canyon exhibit obvious effects on pollutant dispersion. The simulations of pollutant dispersion also show that the transport of pollutants from the canyon to the upper air flow is dominated by the shear layer turbulence near the roof level and the expansion or compression of the air mass in street canyon under real-time boundary wind conditions. Especially, the expansion of the air mass, which features the large scale air movement of the air mass, makes more contribution to the pollutant dispersion in this study. Comparisons of simulated results under different boundary wind conditions indicate that real-time boundary wind conditions produces better condition for pollutant dispersion than the artificially-designed steady boundary wind conditions.

pH-Controlled Bacillus thuringiensis Cry1Ac Protoxin Loading and Release from Polyelectrolyte Microcapsules

PubMed Central

Yang, Wenhui; He, Kanglai; Zhang, Jie; Guo, Shuyuan

2012-01-01

Crystal proteins synthesized by Bacillus thuringiensis (Bt) have been used as biopesticides because of their toxicity to the insect larval hosts. To protect the proteins from environmental stress to extend their activity, we have developed a new microcapsule formulation. Poly (acrylic acid) (PAH) and poly (styrene sulfonate) (PSS) were fabricated through layer-by-layer self-assembly based on a CaCO3 core. Cry1Ac protoxins were loaded into microcapsules through layer-by-layer self-assembly at low pH, and the encapsulated product was stored in water at 4°C. Scanning electron microscopy (SEM) was used to observe the morphology of the capsules. To confirm the successful encapsulation, the loading results were observed with a confocal laser scattering microscope (CLSM), using fluorescein-labeled Cry1Ac protoxin (FITC-Cry1Ac). The protoxins were released from the capsule under the alkaline condition corresponding to the midgut of certain insects, a condition which seldom exists elsewhere in the environment. The following bioassay experiment demonstrated that the microcapsules with Cry1Ac protoxins displayed approximately equivalent insecticidal activity to the Asian corn borer compared with free Cry1Ac protoxins, and empty capsules proved to have no effect on insects. Further result also indicated that the formulation could keep stable under the condition of heat and desiccation. These results suggest that this formulation provides a promising methodology that protects protoxins from the environment and releases them specifically in the target insects’ midgut, which has shown potential as biopesticide in the field. PMID:23024810

Prehension Movements in a Patient (AC) with Posterior Parietal Cortex Damage and Posterior Callosal Section

ERIC Educational Resources Information Center

Frak, Victor; Paulignan, Yves; Jeannerod, Marc; Michel, Francois; Cohen, Henri

2006-01-01

Prehension movements of the right hand were recorded in a right-handed man (AC), with an injury to the left posterior parietal cortex (PPC) and with a section of the left half of the splenium. The kinematic analysis of AC's grasping movements in direct and perturbed conditions was compared to that of five control subjects. A novel effect in…

Established and potential physiological roles of bicarbonate-sensing soluble adenylyl cyclase (sAC) in aquatic animals

PubMed Central

Tresguerres, Martin; Barott, Katie L.; Barron, Megan E.; Roa, Jinae N.

2014-01-01

Soluble adenylyl cyclase (sAC) is a recently recognized source of the signaling molecule cyclic AMP (cAMP) that is genetically and biochemically distinct from the classic G-protein-regulated transmembrane adenylyl cyclases (tmACs). Mammalian sAC is distributed throughout the cytoplasm and it may be present in the nucleus and inside mitochondria. sAC activity is directly stimulated by HCO3−, and sAC has been confirmed to be a HCO3− sensor in a variety of mammalian cell types. In addition, sAC can functionally associate with carbonic anhydrases to act as a de facto sensor of pH and CO2. The two catalytic domains of sAC are related to HCO3−-regulated adenylyl cyclases from cyanobacteria, suggesting the cAMP pathway is an evolutionarily conserved mechanism for sensing CO2 levels and/or acid/base conditions. Reports of sAC in aquatic animals are still limited but are rapidly accumulating. In shark gills, sAC senses blood alkalosis and triggers compensatory H+ absorption. In the intestine of bony fishes, sAC modulates NaCl and water absorption. And in sea urchin sperm, sAC may participate in the initiation of flagellar movement and in the acrosome reaction. Bioinformatics and RT-PCR results reveal that sAC orthologs are present in most animal phyla. This review summarizes the current knowledge on the physiological roles of sAC in aquatic animals and suggests additional functions in which sAC may be involved. PMID:24574382

21 CFR 886.4440 - AC-powered magnet.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and remove...

Heating, Ventilation, Air Conditioning. Resource Manual for Custodial Training Course #3.

ERIC Educational Resources Information Center

Florida State Dept. of Education, Tallahassee. School Plant Management Section.

Intended as a manual to provide school custodians with some understanding of basic functions of heating, ventilating, and air conditioning equipment for safe, efficient operation. Contains general rules and specifications for providing custodians with a more complete awareness of their equipment and the field of "Climate Control" within the…

Inhibition of motor cortex excitability with 15Hz transcranial alternating current stimulation (tACS).

PubMed

Zaghi, Soroush; de Freitas Rezende, Larissa; de Oliveira, Laís Machado; El-Nazer, Rasheda; Menning, Sanne; Tadini, Laura; Fregni, Felipe

2010-08-02

There remains a lack of solid evidence showing whether transcranial stimulation with weak alternating current (transcranial alternating current stimulation, tACS) can in fact induce significant neurophysiological effects. Previously, a study in which tACS was applied for 2 and 5min with current density=0.16-0.25A/m(2) was unable to show robust effects on cortical excitability. Here we applied tACS at a significantly higher current density (0.80A/m(2)) for a considerably longer duration (20min) and were indeed able to demonstrate measurable changes to cortical excitability. Our results show that active 15Hz tACS of the motor cortex (electrodes placed at C3 and C4) significantly diminished the amplitude of motor evoked potentials and decreased intracortical facilitation (ICF) as compared to baseline and sham stimulation. In addition, we show that our method of sham tACS is a reliable control condition. These results support the notion that AC stimulation with weak currents can induce significant changes in brain excitability; in this case, 15Hz tACS led to a pattern of inhibition of cortical excitability. We propose that tACS may have a dampening effect on cortical networks and perhaps interfere with the temporal and spatial summation of weak subthreshold electric potentials. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Improved Tribological Performance of Amorphous Carbon (a-C) Coating by ZrO2 Nanoparticles

PubMed Central

Tang, Jinzhu; Ding, Qi; Zhang, Songwei; Wu, Guizhi; Hu, Litian

2016-01-01

Nanomaterials, such as Graphene, h-BN nanoparticles and MoS2 nanotubes, have shown their ability in improving the tribological performance of amorphous carbon (a-C) coatings. In the current study, the effectiveness of ZrO2 nanoparticles (ZrO2-NPs) in lubricating the self-mated nonhydrogenated a-C contacts was investigated in boundary lubrication regime. The results showed that 13% less friction and 50% less wear compared to the base oil were achieved by employing ZrO2-NPs in the base oil in self-mated a-C contacts. Via analyzing the ZrO2-NPs and the worn a-C surface after tests, it was found that the improved lubrication by ZrO2-NPs was based on “polishing effects”, which is a new phenomenon observed between a-C and nanoparticles. Under the “polishing effect”, micro-plateaus with extremely smooth surface and uniform height were produced on the analyzed a-C surface. The resulting topography of the a-C coating is suitable for ZrO2-NPs to act as nano-bearings between rubbing surfaces. Especially, the ZrO2-NPs exhibited excellent mechanical and chemical stability, even under the severe service condition, suggesting that the combination of nonhydrogenated a-C coating with ZrO2-NPs is an effective, long lasting and environment-friendly lubrication solution. PMID:28773916

Liquid over-feeding air conditioning system and method

DOEpatents

Mei, Viung C.; Chen, Fang C.

1993-01-01

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant.

Effect of operating conditions on performance of silica gel-water air-fluidised desiccant cooler

NASA Astrophysics Data System (ADS)

Rogala, Zbigniew; Kolasiński, Piotr; Gnutek, Zbigniew

2017-11-01

Fluidised desiccant cooling is reported in the literature as an efficient way to provide cooling for air-conditioning purposes. The performance of this technology can be described by electric and thermal Coefficients of Performance (COP) and Specific Cooling Power (SCP). In this paper comprehensive theoretical study was carried out in order to assess the effect of operating conditions such as: superficial air velocity, desiccant particle diameter, bed switching time and desiccant filling height on the performance of fluidised desiccant cooler (FDC). It was concluded that FDC should be filled with as small as possible desiccant particles featuring diameters and should not be operated with shorter switching times than optimum. Moreover in order to efficiently run such systems superficial air velocities during adsorption and desorption should be similar. At last substantial effect of desiccant filling height on performance of FDC was presented.

Air Conditioning with Magnetic Refrigeration : An Efficient, Green Compact Cooling System Using Magnetic Refrigeration

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-09-01

BEETIT Project: Astronautics is developing an air conditioning system that relies on magnetic fields. Typical air conditioners use vapor compression to cool air. Vapor compression uses a liquid refrigerant to circulate within the air conditioner, absorb the heat, and pump the heat out into the external environment. Astronautics’ design uses a novel property of certain materials, called “magnetocaloric materials”, to achieve the same result as liquid refrigerants. These magnetocaloric materials essentially heat up when placed within a magnetic field and cool down when removed, effectively pumping heat out from a cooler to warmer environment. In addition, magnetic refrigeration uses nomore » ozone-depleting gases and is safer to use than conventional air conditioners which are prone to leaks.« less

Acanthamoeba belonging to T3, T4, and T11: genotypes isolated from air-conditioning units in Santiago, Chile.

PubMed

Astorga, Berbeli; Lorenzo-Morales, Jacob; Martín-Navarro, Carmen M; Alarcón, Verónica; Moreno, Johanna; González, Ana C; Navarrete, Elizabeth; Piñero, José E; Valladares, Basilio

2011-01-01

Free-living amoebae (FLA) of the genus Acanthamoeba are widely distributed in the environment, in the air, soil, and water, and have also been isolated from air-conditioning units. The objective of this work was to investigate the presence of this genus of FLA in the air-conditioning equipment at the Institute of Public Health of Chile in Santiago, Chile. Water and air samples were collected from air-conditioning systems and were checked for the presence of Acanthamoeba spp. Positive samples were further classified at the genotype level after sequencing the highly variable diagnostic fragment 3 (DF3) region of the 18S rRNA gene. This is the first report of the T3, T4, and T11 genotypes of Acanthamoeba in air-conditioning units from Chile. Overall, the widespread distribution of potentially pathogenic Acanthamoeba strains in the studied source demands more awareness within the public and health professionals in Chile as this pathogen is emerging as a risk for human health worldwide. © 2011 The Author(s) Journal of Eukaryotic Microbiology © 2011 International Society of Protistologists.

Ground-water conditions at Beale Air Force Base and vicinity, California

USGS Publications Warehouse

Page, R.W.

1980-01-01

Ground-water conditions were studied in a 168-square-mile area between the Sierra Nevada and the Feather River in Yuba County, Calif. The area is in the eastern part of the Sacramento Valley and includes most of Beale Air Force Base. Source, occurrence, movement, and chemical quality of the ground water were evaluated. Ground water occurs in sedimentary and volcanic rocks of Tertiary and Quaternary age. The base of the freshwater is in the undifferentiated sedimentary rocks of Oligocene and Eocene age, that contain water of high dissolved-solids concentration. The ground water occurs under unconfined and partly confined conditions. At Beale Air Force Base it is at times partly confined. Recharge is principally from the rivers. Pumpage in the study area was estimated to be 129,000 acre-feet in 1975. In the 1960's, water levels in most parts of the study area declined less rapidly than in earlier years or became fairly stable. In the 1970's, water levels at Beale Air Force Base declined only slightly. Spacing of wells on the base and rates of pumping are such that excessive pumping interference is avoided. Water quality at the base and throughout the study area is generally good. Dissolved-solids concentrations are 700 to 900 milligrams per liter in the undifferentiated sedimentary rocks beneath the base well field. (USGS)

Effects of a diet containing genetically modified rice expressing the Cry1Ab/1Ac protein (Bacillus thuringiensis toxin) on broiler chickens.

PubMed

Li, Zeyang; Gao, Yang; Zhang, Minhong; Feng, Jinghai; Xiong, Yandan

2015-01-01

The aim of this study was to evaluate the effect of feeding Bacillus thuringiensis (Bt) rice expressing the Cry1Ab/1Ac protein on broiler chicken. The genetically modified (GM) Bt rice was compared with the corresponding non-GM rice regarding performance of feeding groups, their health status, relative organ weights, biochemical serum parameters and occurrence of Cry1Ab/1Ac gene fragments. One hundred and eighty day-old Arbor Acres female broilers with the same health condition were randomly allocated to the two treatments (6 replicate cages with 15 broilers in each cage per treatment). They received diets containing GM rice (GM group) or its parental non-GM rice (non-GM group) at 52-57% of the air-dried diet for 42 days. The results show that the transgenic rice had a similar nutrient composition as the non-GM rice and had no adverse effects on chicken growth, biochemical serum parameters and necropsy during the 42-day feeding period. In birds fed the GM rice, no transgenic gene fragments were detected in the samples of blood, liver, kidneys, spleen, jejunum, ileum, duodenum and muscle tissue. In conclusion, the results suggest that Bt rice expressing Cry1Ab/1Ac protein has no adverse effects on broiler chicken. Therefore, it can be considered as safe and used as feed source for broiler chicken.

Sorption and biodegradation of six pharmaceutically active compounds under four different redox conditions.

PubMed

de Wilt, Arnoud; He, Yujie; Sutton, Nora; Langenhoff, Alette; Rijnaarts, Huub

2018-02-01

This study explored the removal of six pharmaceutically active compounds (PhACs) in lab-scale experiments with sediments under four redox conditions, namely aerobic, nitrate reducing, sulfate reducing, and methanogenic conditions using batch and column set-ups. Redox conditions were found to influence PhAC removal by sorption and biodegradation. The most optimal PhAC removal was observed at the outer ranges of the redox spectrum, i.e. either aerobic or deep anaerobic (sulfate reducing and methanogenic conditions), whereas nitrate reducing conditions were found least effective for PhACs biodegradation and sorption. For instance, sorption coefficient K d values for metoprolol in column experiments were 90, 65, 42 and 11 L/kg for sulfate reducing, methanogenic, aerobic and nitrate reducing conditions, respectively. For the same conditions K d values for propranolol were 101, 94, 55 and 55 L/kg, respectively. As expected, biodegradation efficiencies were highest under aerobic conditions, showing >99% removal of caffeine and naproxen, but no removal for propranolol and carbamazepine. The adaptive capacity of sediment was demonstrated by pre-exposure to PhACs leading to improved PhAC biodegradation. The results of this study indicate the necessity to combine diverse redox conditions, including aerobic conditions, for maximizing PhAC removal by sorption and biodegradation. Furthermore, our findings stress the need for additional treatment measures as recalcitrant PhACs are not effectively removed under any redox condition. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE... in a manner that prevents any members or devices used to support the bar from contacting the package...

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE... in a manner that prevents any members or devices used to support the bar from contacting the package...

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE... in a manner that prevents any members or devices used to support the bar from contacting the package...

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE... in a manner that prevents any members or devices used to support the bar from contacting the package...

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE... in a manner that prevents any members or devices used to support the bar from contacting the package...

Technology evaluation of heating, ventilation, and air conditioning for MIUS application

NASA Technical Reports Server (NTRS)

Gill, W. L.; Keough, M. B.; Rippey, J. O.

1974-01-01

Potential ways of providing heating, ventilation, and air conditioning for a building complex serviced by a modular integrated utility system (MIUS) are examined. Literature surveys were conducted to investigate both conventional and unusual systems to serve this purpose. The advantages and disadvantages of the systems most compatible with MIUS are discussed.

Analysis of alkaline exchange membrane fuel cells performance at different operating conditions using DC and AC methods

NASA Astrophysics Data System (ADS)

Reshetenko, Tatyana; Odgaard, Madeleine; Schlueter, Debbie; Serov, Alexey

2018-01-01

Membrane electrode assemblies (MEAs) for anion exchange membrane fuel cells (AEMFCs) were manufactured from commercial materials: Pt/C catalyst, A201 AEM and AS4 ionomer by using an industrial mass-production digital printing method. The MEA designs selected are close to those recommended by US Department of Energy, including low loading of platinum on the cathode side (0.2 mg cm-2). Polarization curves and electrochemical impedance spectroscopy (EIS) were applied for MEA evaluation in fuel cell conditions with variation of gas humidification and oxygen partial pressure (air vs oxygen). The typical impedance curves recorded at H2/O2 gas configuration consist of high- and medium-frequency arcs responsible for hydrogen oxidation and oxygen reduction, respectively. Operation with air as a cathode feed gas resulted in a decrease in AEMFC performance due to possible CO2 poisoning and mass transfer losses. At the same time, EIS demonstrated formation of a low frequency loop due to diffusion limitations. Despite the low loading of platinum on the cathode (0.2 mg cm-2), a peak power density of ∼330 mW cm-2 was achieved (at 50/50% of RH on anode and cathode), which is substantially higher performance than for AEMFC MEAs tested at similar conditions.

Mold contamination of automobile air conditioner systems.

PubMed

Kumar, P; Lopez, M; Fan, W; Cambre, K; Elston, R C

1990-02-01

Eight cars belonging to patients who were found to have exacerbation of allergic rhinitis and bronchial asthma after turning on the air conditioner in their cars were examined. Mold concentrations inside the passenger compartment with the a/c turned off and at different climate control settings were lower than concentrations in the outside air. After turning on the air conditioner to "Max", cultures obtained at various intervals revealed that mold concentrations decreased significantly with time. Furthermore, placement of a filter at the portal of entry of outside air significantly reduced the mold concentration in the passenger compartment.

Human thermal bioclimatic conditions associated with acute cardiovascular syndromes in Crete Island, Greece

NASA Astrophysics Data System (ADS)

Bleta, Anastasia G.; Nastos, Panagiotis T.

2013-04-01

The aim of this study is to quantify the association between bioclimatic conditions and daily counts of admissions for non-fatal acute cardiovascular (acute coronary syndrome, arrhythmia, decompensation of heart failure) syndromes (ACS) registered by the two main hospitals in Heraklion, Crete Island, during a five-year period 2008-2012. The bioclimatic conditions analyzed are based on human thermal bioclimatic indices such as the Physiological Equivalent Temperature (PET) and the Universal Thermal Climate Index (UTCI). Mean daily meteorological parameters, such as air temperature, relative humidity, wind speed and cloudiness, were acquired from the meteorological station of Heraklion (Hellenic National Meteorological Service). These parameters were used as input variables in modeling the aforementioned thermal indices, in order to interpret the grade of the thermo-physiological stress. The PET and UTCI analysis was performed by the use of the radiation and bioclimate model, "RayMan", which is well-suited to calculate radiation fluxes and human biometeorological indices. Generalized linear models (GLM) were applied to time series of daily numbers of outpatients with ACS against bioclimatic variations, after controlling for possible confounders and adjustment for season and trends. The interpretation of the results of this analysis suggests a significant association between cold weather and increased coronary heart disease incidence, especially in the elderly and males. Additionally, heat stress plays an important role in the configuration of daily ACS outpatients, even in temperate climate, as that in Crete Island. In this point it is worth mentioning that Crete Island is frequently affected by Saharan outbreaks, which are associated in many cases with miscellaneous phenomena, such as Föhn winds - hot and dry winds - causing extreme bioclimatic conditions (strong heat stress). Taking into consideration the projected increased ambient temperature in the future, ACS

Assessing the impacts of seasonal and vertical atmospheric conditions on air quality over the Pearl River Delta region

NASA Astrophysics Data System (ADS)

Tong, Cheuk Hei Marcus; Yim, Steve Hung Lam; Rothenberg, Daniel; Wang, Chien; Lin, Chuan-Yao; Chen, Yongqin David; Lau, Ngar Cheung

2018-05-01

Air pollution is an increasingly concerning problem in many metropolitan areas due to its adverse public health and environmental impacts. Vertical atmospheric conditions have strong effects on vertical mixing of air pollutants, which directly affects surface air quality. The characteristics and magnitude of how vertical atmospheric conditions affect surface air quality, which are critical to future air quality projections, have not yet been fully understood. This study aims to enhance understanding of the annual and seasonal sensitivities of air pollution to both surface and vertical atmospheric conditions. Based on both surface and vertical meteorological characteristics provided by 1994-2003 monthly dynamic downscaling data from the Weather and Research Forecast Model, we develop generalized linear models (GLMs) to study the relationships between surface air pollutants (ozone, respirable suspended particulates, and sulfur dioxide) and atmospheric conditions in the Pearl River Delta (PRD) region. Applying Principal Component Regression (PCR) to address multi-collinearity, we study the contributions of various meteorological variables to pollutants' concentration levels based on the loading and model coefficient of major principal components. Our results show that relatively high pollutant concentration occurs under relatively low mid-level troposphere temperature gradients, low relative humidity, weak southerly wind (or strong northerly wind) and weak westerly wind (or strong easterly wind). Moreover, the correlations vary among pollutant species, seasons, and meteorological variables at various altitudes. In general, pollutant sensitivity to meteorological variables is found to be greater in winter than in other seasons, and the sensitivity of ozone to meteorology differs from that of the other two pollutants. Applying our GLMs to anomalous air pollution episodes, we find that meteorological variables up to mid troposphere (∼700 mb) play an important role in

The Maintenance of Heating, Ventilating and Air-Conditioning Systems and Indoor Air Quality in Schools: A Guide for School Facility Managers. Technical Bulletin.

ERIC Educational Resources Information Center

Wheeler, Arthur E.

To help maintain good indoor air quality (IAQ) in schools, guidance for the development and implementation of an effective program for maintenance and operation of heating, ventilating, and air-conditioning (HVAC) systems are discussed. Frequently, a building's occupants will complain about IAQ when the temperature or humidity are at uncomfortable…

Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners.

PubMed

Batterman, S; Du, L; Mentz, G; Mukherjee, B; Parker, E; Godwin, C; Chin, J-Y; O'Toole, A; Robins, T; Rowe, Z; Lewis, T

2012-06-01

This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84±27%, but dropped to 63±33% in subsequent seasons. In months when households were not visited, use averaged only 34±30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. Environmental tobacco smoke (ETS) increased particulate matter (PM) levels by about 14 μg/m3 and was often detected using ETS-specific tracers despite restrictions on smoking in the house as reported on questionnaires administered to caregivers. PM concentrations depended on season, filter usage, relative humidity, air exchange ratios, number of children, outdoor PM levels, sweeping/dusting, and presence of a central air conditioner (AC). Free-standing air filters can be an effective intervention that provides substantial reductions in PM concentrations if the filters are used. However, filter use was variable across the study population and declined over the study duration, and

N-type Cu2O doped activated carbon as catalyst for improving power generation of air cathode microbial fuel cells.

PubMed

Zhang, Xi; Li, Kexun; Yan, Pengyu; Liu, Ziqi; Pu, Liangtao

2015-01-01

A novel n-type Cu2O doped activated carbon (AC) air cathode (Cu/AC) was developed as an alternative to Pt electrode for oxygen reduction in microbial fuel cells (MFCs). The maximum power density of MFCs using this novel air cathode was as high as 1390±76mWm(-2), almost 59% higher than the bare AC air cathode. Specifically, the resistance including total resistance and charge transfer resistance significantly decreased comparing to the control. Tafel curve also showed the faster electro-transfer kinetics of Cu/AC with exchange current density of 1.03×10(-3)Acm(-2), which was 69% higher than the control. Ribbon-like Cu2O was deposited on the surface of AC with the mesopore surface area increasing. Cubic Cu2O crystals exclusively expose (111) planes with the interplanar crystal spacing of 2.48Å, which was the dominate active sites for oxygen reduction reaction (ORR). N-type Cu2O with oxygen vacancies played crucial roles in electrochemical catalytic activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Design of Large Geothermally Powered Air-Conditioning Systems Using an Optimal Control Approach

NASA Astrophysics Data System (ADS)

Horowitz, F. G.; O'Bryan, L.

2010-12-01

The direct use of geothermal energy from Hot Sedimentary Aquifer (HSA) systems for large scale air-conditioning projects involves many tradeoffs. Aspects contributing towards making design decisions for such systems include: the inadequately known permeability and thermal distributions underground; the combinatorial complexity of selecting pumping and chiller systems to match the underground conditions to the air-conditioning requirements; the future price variations of the electricity market; any uncertainties in future Carbon pricing; and the applicable discount rate for evaluating the financial worth of the project. Expanding upon the previous work of Horowitz and Hornby (2007), we take an optimal control approach to the design of such systems. By building a model of the HSA system, the drilling process, the pumping process, and the chilling operations, along with a specified objective function, we can write a Hamiltonian for the system. Using the standard techniques of optimal control, we use gradients of the Hamiltonian to find the optimal design for any given set of permeabilities, thermal distributions, and the other engineering and financial parameters. By using this approach, optimal system designs could potentially evolve in response to the actual conditions encountered during drilling. Because the granularity of some current models is so coarse, we will be able to compare our optimal control approach to an exhaustive search of parameter space. We will present examples from the conditions appropriate for the Perth Basin of Western Australia, where the WA Geothermal Centre of Excellence is involved with two large air-conditioning projects using geothermal water from deep aquifers at 75 to 95 degrees C.

Performance analysis of air conditioning system and airflow simulation in an operating theater

NASA Astrophysics Data System (ADS)

Alhamid, Muhammad Idrus; Budihardjo, Rahmat

2018-02-01

The importance of maintaining performance of a hospital operating theater is to establish an adequate circulation of clean air within the room. The parameter of air distribution in a space should be based on Air Changes per Hour (ACH) to maintain a positive room pressure. The dispersion of airborne particles in the operating theater was governed by regulating the air distribution so that the operating theater meets clean room standards ie ISO 14664 and ASHRAE 170. Here, we introduced several input parameters in a simulation environment to observe the pressure distribution in the room. Input parameters were air temperature, air velocity and volumetric flow rate entering and leaving room for existing and designed condition. In the existing operating theatre, several observations were found. It was found that the outlet air velocity at the HEPA filter above the operating table was too high thus causing a turbulent airflow pattern. Moreover, the setting temperature at 19°C was found to be too low. The supply of air into the room was observed at lower than 20 ACH which is under the standard requirement. Our simulation using FloVent 8.2™ program showed that not only airflow turbulence could be reduced but also the amount of particle contamination could also be minimized.

The AC 2000.2 Catalogue

NASA Astrophysics Data System (ADS)

Urban, S. E.; Corbin, T. E.; Wycoff, G. L.; Makarov, V. V.; Høg, E.; Fabricius, C.

2001-12-01

For over 100 years, the international project known as the Astrographic Catalogue -- which involved 20 observatories tasked to photograph the sky -- has held an unfulfilled promised of yielding a wealth of astrometric information. This promise was not realized due to the inadequate reductions of the project's plates. However, in 1997 the U.S. Naval Observatory (USNO) completed the reductions of the 22,660 plates. That catalogue, named the AC 2000, contained positions and magnitudes for 4.6 million stars down to about v magnitude 12.5. Due to the early epochs of the data -- averaging 1907 -- and the positional accuracies -- between 150 and 400 milliarcseconds -- the data are extremely valuable in computing proper motions. In 1997, these positions were used to form the proper motions of the ACT Reference Catalogue. In 1999, USNO and Copenhagen University Observatory (CUO) partnered to create the Tycho-2 Catalogue. The CUO group re-analyzed the data from the Tycho experiment on the Hipparcos satellite. The USNO group re-analyzed over 140 positional catalogs which were combined with the expanded Tycho positions from the CUO group to compute the Tycho-2 proper motions. The largest contributor to these proper motions was the re-analyzed Astrographic Catalogue; the latest version being known as the AC 2000.2 Catalogue. There are two major differences between the AC 2000 and the AC 2000.2. First, the reference catalog used in AC 2000.2 was an expanded version of the Astrographic Catalogue Reference Stars that was rigorously derived on the Hipparcos Celestial Reference Frame. The second is that AC 2000.2 contains photometry from Tycho-2, where available. A description of the AC 2000.2 Catalogue, the reduction techniques used, how it compares with the 1997 version, and information on obtaining the data will be presented.

Sea/Lake Water Air Conditioning at Naval Facilities.

DTIC Science & Technology

1980-05-01

ECONOMICS AT TWO FACILITIES ......... ................... 2 Facilities ........... .......................... 2 Computer Models...of an operational test at Naval Security Group Activity (NSGA) Winter Harbor, Me., and the economics of Navywide application. In FY76 an assessment of... economics of Navywide application of sea/lake water AC indicated that cost and energy savings at the sites of some Naval facilities are possible, depending

Initial NIST AC QHR Measurements

PubMed Central

Cage, M. E.; Shields, S. H.; Jeffery, A.

2004-01-01

We demonstrate that dc quantized Hall resistance (dc QHR) guideline properties and dc and ac QHR values can be measured without changing sample probe lead connections at the QHR device, and report ac QHR values that converge to the dc QHR value when using four-terminal-pair ac QHR measurements. This was accomplished during one cooldown using single-series and quadruple-series connections outside the sample probe. The QHR was measured from 0 Hz to 5500 Hz in 1:1 ratio at 20 µA to ±1 part in 107 uncertainties with a poor-quality QHR device. A good device would allow an order of magnitude smaller uncertainties over this frequency range. We exchanged positions of the QHR device and reference resistor in the bridge and remeasured the resistance ratios to remove dominant ac bridge effects. PMID:27366620

Effect of Intake Air Filter Condition on Vehicle Fuel Economy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norman, Kevin M; Huff, Shean P; West, Brian H

2009-02-01

The U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy and the U.S. Environmental Protection Agency (EPA) jointly maintain a fuel economy website (www.fueleconomy.gov), which helps fulfill their responsibility under the Energy Policy Act of 1992 to provide accurate fuel economy information [in miles per gallon (mpg)] to consumers. The site provides information on EPA fuel economy ratings for passenger cars and light trucks from 1985 to the present and other relevant information related to energy use such as alternative fuels and driving and vehicle maintenance tips. In recent years, fluctuations in the price of crude oilmore » and corresponding fluctuations in the price of gasoline and diesel fuels have renewed interest in vehicle fuel economy in the United States. (User sessions on the fuel economy website exceeded 20 million in 2008 compared to less than 5 million in 2004 and less than 1 million in 2001.) As a result of this renewed interest and the age of some of the references cited in the tips section of the website, DOE authorized the Oak Ridge National Laboratory (ORNL) Fuels, Engines, and Emissions Research Center (FEERC) to initiate studies to validate and improve these tips. This report documents a study aimed specifically at the effect of engine air filter condition on fuel economy. The goal of this study was to explore the effects of a clogged air filter on the fuel economy of vehicles operating over prescribed test cycles. Three newer vehicles (a 2007 Buick Lucerne, a 2006 Dodge Charger, and a 2003 Toyota Camry) and an older carbureted vehicle were tested. Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a

Analysis of AIRS and IASI System Performance Under Clear and Cloudy Conditions

NASA Technical Reports Server (NTRS)

Aumann, Hartmut H.; Strow, L. Larrabee

2010-01-01

The radiometric and spectral system performance of space-borne infrared radiometers is generally specified and analyzed under strictly cloud-free, spatially uniform and warm conditions, with the assumption that the observed performance applies to the full dynamic range under clear and cloudy conditions and that random noise cancels for the evaluation of the radiometric accuracy. Such clear conditions are found in only one percent of the data. Ninety nine percent of the data include clouds, which produce spatially highly non-uniform scenes with 11 micrometers window brightness temperatures as low as 200K. We use AIRS and IASI radiance spectra to compare system performance under clear and a wide range of cloudy conditions. Although the two instruments are in polar orbits, with the ascending nodes separated by four hours, daily averages already reveal surprisingly similar measurements. The AIRS and IASI radiometric performance based on the mean of large numbers of observation is comparable and agrees within 200 mK over a wide range of temperatures. There are also some unexpected differences at the 200 -500 mK level, which are of significance for climate applications. The results were verified with data from July 2007 through January 2010, but many can already be gleaned from the analysis of a single day of data.

Simultaneous distribution of AC and DC power

DOEpatents

Polese, Luigi Gentile

2015-09-15

A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

Urban air quality assessment using monitoring data of fractionized aerosol samples, chemometrics and meteorological conditions.

PubMed

Yotova, Galina I; Tsitouridou, Roxani; Tsakovski, Stefan L; Simeonov, Vasil D

2016-01-01

The present article deals with assessment of urban air by using monitoring data for 10 different aerosol fractions (0.015-16 μm) collected at a typical urban site in City of Thessaloniki, Greece. The data set was subject to multivariate statistical analysis (cluster analysis and principal components analysis) and, additionally, to HYSPLIT back trajectory modeling in order to assess in a better way the impact of the weather conditions on the pollution sources identified. A specific element of the study is the effort to clarify the role of outliers in the data set. The reason for the appearance of outliers is strongly related to the atmospheric condition on the particular sampling days leading to enhanced concentration of pollutants (secondary emissions, sea sprays, road and soil dust, combustion processes) especially for ultra fine and coarse particles. It is also shown that three major sources affect the urban air quality of the location studied-sea sprays, mineral dust and anthropogenic influences (agricultural activity, combustion processes, and industrial sources). The level of impact is related to certain extent to the aerosol fraction size. The assessment of the meteorological conditions leads to defining of four downwind patterns affecting the air quality (Pelagic, Western and Central Europe, Eastern and Northeastern Europe and Africa and Southern Europe). Thus, the present study offers a complete urban air assessment taking into account the weather conditions, pollution sources and aerosol fractioning.

Effects of water nanodroplets on skin moisture and viscoelasticity during air-conditioning.

PubMed

Ohno, Hideo; Nishimura, Naoki; Yamada, Kuniyuki; Shimizu, Yuuki; Iwase, Satoshi; Sugenoya, Junichi; Sato, Motohiko

2013-11-01

In air-conditioned rooms, dry air exacerbates some skin diseases, for example, senile xerosis, atopic dermatitis, and surface roughness. Humidifiers are used to improve air dryness, which often induces excess humidity and thermal discomfort. To address this issue, we investigated the effects of water nanodroplets (mist) on skin hydration, which may increase skin hydration by penetrating into the interstitial spaces between corneocytes of the stratum corneum (SC) without increasing air humidity. We examined biophysical parameters, including skin conductance and transepidermal water loss (TEWL), and biomechanical parameters of skin distension/retraction before and after suction at the forehead, lateral canthus, and cheek, with or without mist, in a testing environment (24°C, 35% relative humidity) for 120 min. In the group without mist, TEWL values significantly decreased at all the sites after 1 h compared with the initial values. However, in the presence of mist, TEWL values were maintained at the initial values through the test, yielding significant differences vs. the group without mist. There were no significant differences between mist and mist-free groups in terms of skin conductance. Skin distension was significantly increased in the group with mist compared with that in the group without mist at the forehead and cheek, suggesting a softening effect of mist. Skin deformation of the face was improved by mist, suggesting hydration of the SC by mist. The change in TEWL was influenced by mist, suggesting supply of water to the skin, particularly the SC, by mist. These data indicated that a mist of water nanodroplets played an important role in softening skin in an air-conditioned room without increasing excess humidity. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

V-TECS Guide for Automobile Air Conditioning and Electrical System Technician.

ERIC Educational Resources Information Center

Meyer, Calvin F.; Benson, Robert T.

This curriculum guide provides an outline for an eight-unit course to train automobile air conditioning and electrical system technicians. Each unit focuses on a duty that is composed of a number of performance objectives. For each objective, these materials are provided: a task, a standard of performance of task, source of standard, conditions…

The minimization of ac phase noise in interferometric systems

NASA Astrophysics Data System (ADS)

Filinski, I.; Gordon, R. A.

1994-03-01

A simple step-by-step procedure, including several novel techniques discussed in the Appendices, is given for minimizing ac phase noise in typical interferometric systems such as two-beam interferometers, holographic setups, four-wave mixers, etc. Special attention is given to index of refraction fluctuations, direct mechanical coupling, and acoustic coupling, whose importance in determining ac phase noise in interferometric systems has not been adequately treated. The minimization procedure must be carried out while continuously monitoring the phase noise which can be done very simply by using a photodiode measurement of the interferometer output. Supplementary measurements using a microphone and accelerometer will also be helpful in identifying the sources of phase noise. Emphasis is placed on new techniques or new modifications of older techniques which will not usually be familiar to most workers in optics. Thus, the necessity of eliminating the effects of index of refraction fluctuations which degrade the performance of all interferometers is pointed out as the first priority. A substantial decrease of the effects of all vibrating, rotating, or flowing masses (e.g., cooling lines) in direct contact with the optical table will also have to be carefully carried out regardless of the type of interferometric system employed. It is recommended that this be followed by a simple, inexpensive change to a novel type of interferometer discussed in Appendix A which is inherently less sensitive to mechanical vibration. Such a change will lead to a reduction of both low-frequency and high-frequency ac phase noise by more than an order of magnitude and can be carried out for all interferometers with the exception of multiple pass optical systems and high-resolution FFT spectrometers. It is pointed out that most homemade air bladder vibration isolators are used incorrectly and do not provide sufficient reduction in the contribution of floor vibrations to phase noise. Several

Control systems for heating, ventilating, and air conditioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haines, R.W.

1977-01-01

Hundreds of ideas for designing and controlling sophisticated heating, ventilating and air conditioning (HVAC) systems are presented. Information is included on enthalpy control, energy conservation in HVAC systems, on solar heating, cooling and refrigeration systems, and on a self-draining water collector and heater. Computerized control systems and the economics of supervisory systems are discussed. Information is presented on computer system components, software, relevant terminology, and computerized security and fire reporting systems. Benefits of computer systems are explained, along with optimization techniques, data management, maintenance schedules, and energy consumption. A bibliography, glossaries of HVAC terminology, abbreviations, symbols, and a subject indexmore » are provided. (LCL)« less

Do-It-Yourself Additives Recharge Auto Air Conditioning

NASA Technical Reports Server (NTRS)

2010-01-01

In planning for a return mission to the Moon, NASA aimed to improve the thermal control systems that keep astronauts comfortable and cool while inside a spacecraft. Goddard Space Flight Center awarded a Small Business Innovation Research (SBIR) contract to Mainstream Engineering Corporation, of Rockledge, Florida, to develop a chemical/mechanical heat pump. IDQ Inc., of Garland, Texas, exclusively licensed the technology and incorporates it into its line of Arctic Freeze products for automotive air conditioning applications. While working on the design, Mainstream Engineering came up with a unique liquid additive called QwikBoost to enhance the performance of the advanced heat pump design.

Liquid over-feeding air conditioning system and method

DOEpatents

Mei, V.C.; Chen, F.C.

1993-09-21

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant. 1 figure.

Using Field-Metered Data to Quantify Annual Energy Use of Portable Air Conditioners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burke, Thomas; Willem, Henry; Ni, Chun Chun

2014-12-01

As many regions of the United States experience rising temperatures, consumers have come to rely increasingly on cooling appliances (including portable air conditioners) to provide a comfortable indoor temperature. Home occupants sometimes use a portable air conditioner (PAC) to maintain a desired indoor temperature in a single room or enclosed space. Although PACs in residential use are few compared to centrally installed and room air conditioning (AC) units, the past few years have witnessed an increase of PACs use throughout the United States. There is, however, little information and few research projects focused on the energy consumption and performance ofmore » PACs, particularly studies that collect information from field applications of PACs. The operation and energy consumption of PACs may differ among geographic locations and households, because of variations in cooling load, frequency, duration of use, and other user-selected settings. In addition, the performance of building envelope (thermal mass and air leakage) as well as inter-zonal mixing within the building would substantially influence the ability to control and maintain desirable indoor thermal conditions. Lawrence Berkeley National Laboratory (LBNL) conducted an initial field-metering study aimed at increasing the knowledge and data related to PAC operation and energy consumption in the United States.« less

A MEMS sensor for AC electric current

NASA Astrophysics Data System (ADS)

Leland, Eli Sidney

This manuscript describes the development of a new MEMS sensor for the measurement of AC electric current. The sensor is comprised of a MEMS piezoelectric cantilever with a microscale permanent magnet mounted to the cantilever's free end. When placed near a wire carrying AC current, the magnet couples to the oscillating magnetic field surrounding the wire, causing the cantilever to deflect, and piezoelectric coupling produces a sinusoidal voltage proportional to the current in the wire. The sensor is itself passive, requiring no power supply to operate. It also operates on proximity and need only be placed near a current carrier in order to function. The sensor does not need to encircle the current carrier and it therefore can measure current in two-wire zip-cords without necessitating the separation of the two conductors. Applications for tins sensor include measuring residential and commercial electricity use and monitoring electric power distribution networks. An analytical model describing the behavior of the current sensor was developed. This model was also adapted to describe the power output of an energy scavenger coupled to a wire carrying AC current. A mesoscale sensor exhibited a sensitivity of 75 mV/A when measuring AC electric current in a zip-cord. A mesoscale energy scavenger produced 345 muW when coupled to a zip-cord carrying 13 A. MEMS current sensors were fabricated from aluminum nitride piezoelectric cantilevers and composite permanent magnets. The cantilevers were fabricated using a four-mask process. Microscale permanent magnets were dispenser-printed using NdFeB magnetic powder with an epoxy binder. The MEMS AC current sensor was interfaced with amplification circuitry and packaged inside an almninum enclosure. The sensor was also integrated with a mesoscale energy scavenger and power conditioning circuitry to create a fully self-powered current sensor. Unamplified sensitivity of the sensor was 0.1-1.1 mV/A when measuring currents in single

Tourists' attitudes towards ban on smoking in air-conditioned hotel lobbies in Thailand.

PubMed

Viriyachaiyo, V; Lim, A

2009-06-01

Thailand is internationally renowned for its stringent tobacco control measures. In Thailand, a regulation banning smoking in air-conditioned hotel lobbies was issued in late 2006, causing substantial apprehension within the hospitality industry. A survey of tourists' attitudes toward the ban was conducted. A cross-sectional survey of 5550 travellers staying in various hotels in Bangkok, Surat Thani, Phuket, Krabi and Songkhla provinces, October 2005 to December 2006. Travellers aged 15 years or older with a check-in duration of at least one day and willing to complete the questionnaire were requested by hotel staff to fill in the 5-minute questionnaire at check-in or later at their convenience. Secondhand cigarette smoke was recognised as harmful to health by 89.7% of respondents. 47.8% of travellers were aware of the Thai regulation banning smoking in air-conditioned restaurants. 80.9% of the respondents agreed with the ban, particularly female non-smokers. 38.6% of survey respondents indicated that they would be more likely to visit Thailand again because of the regulation, 53.4% that the regulation would not affect their decision and 7.9% that they would be less likely to visit Thailand again. Banning smoking in air-conditioned hotel lobbies in Thailand is widely supported by tourists. Enforcement of the regulation is more likely to attract tourists than dissuade them from holidaying in Thailand.

MicroPPT-Based Secondary/Backup ACS for a 160-m, 450-kg Solar Sail Spacecraft

NASA Technical Reports Server (NTRS)

Wie, Bong; Murphy, David

2005-01-01

Solar sail tip-mounted, lightweight pulsed plasma thrusters (PPTs) are proposed for a secondary (or backup) attitude control system (ACS) of a 160-m, 450-kg solar sail spacecraft of the Solar Polar Imager (SPI) mission. A propellantless primary ACS of the SPI sailcraft employs trim control masses running along mast lanyards for pitch/yaw control together with roll stabilizer bars at the mast tips for quadrant tilt (roll) control. The robustness of such a propellantless primary ACS would be further enhanced by a secondary ACS utilizing tip-mounted, lightweight PPTs. The microPPT-based ACS is intended mainly for attitude recovery maneuvers from various off-nominal conditions that cannot be reliably handled by the propellantless primary ACS. However, it can also be employed for: i) the checkout or standby mode prior to and during sail deployment, ii) the post-deployment transition mode (prior to the propellantless primary ACS mode operation), iii) the solar sailing cruise mode of a trimmed sailcraft, and iv) the spin-stabilized, sun-pointing, safe mode. Although a conventional bus ACS is required for the SPI mission as the sail is jettisoned at the start of its science mission phase, the microPPT-based ACS option promises greater redundancy and robustness for the SPI mission. For other sailing missions, where the sail is never jettisoned, this secondary ACS provides a lower-cost, lower-mass propulsion for deployment control and greater redundancy than any traditional reaction-jet control system. This paper presents an overview nf the state--of-the--art microPPT technology, the design requirements of microPPTs for solar sail attitude control, and the preliminary ACS design and simulation results.

Surface pre-conditioning with bioactive glass air-abrasion can enhance enamel white spot lesion remineralization.

PubMed

Milly, Hussam; Festy, Frederic; Andiappan, Manoharan; Watson, Timothy F; Thompson, Ian; Banerjee, Avijit

2015-05-01

To evaluate the effect of pre-conditioning enamel white spot lesion (WSL) surfaces using bioactive glass (BAG) air-abrasion prior to remineralization therapy. Ninety human enamel samples with artificial WSLs were assigned to three WSL surface pre-conditioning groups (n=30): (a) air-abrasion with BAG-polyacrylic acid (PAA-BAG) powder, (b) acid-etching using 37% phosphoric acid gel (positive control) and (c) unconditioned (negative control). Each group was further divided into three subgroups according to the following remineralization therapy (n=10): (I) BAG paste (36 wt.% BAG), (II) BAG slurry (100 wt.% BAG) and (III) de-ionized water (negative control). The average surface roughness and the lesion step height compared to intra-specimen sound enamel reference points were analyzed using non-contact profilometry. Optical changes within the lesion subsurface compared to baseline scans were assessed using optical coherence tomography (OCT). Knoop microhardness evaluated the WSLs' mechanical properties. Raman micro-spectroscopy measured the v-(CO3)(2-)/v1-(PO4)(3-) ratio. Structural changes in the lesion were observed using confocal laser scanning microscopy (CLSM) and scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX). All comparisons were considered statistically significant if p<0.05. PAA-BAG air-abrasion removed 5.1 ± 0.6 μm from the lesion surface, increasing the WSL surface roughness. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion reduced subsurface light scattering, increased the Knoop microhardness and the mineral content of the remineralized lesions (p<0.05). SEM-EDX revealed mineral depositions covering the lesion surface. BAG slurry resulted in a superior remineralization outcome, when compared to BAG paste. Pre-conditioning WSL surfaces with PAA-BAG air-abrasion modified the lesion surface physically and enhanced remineralization using BAG 45S5 therapy. Copyright © 2015 Academy of Dental Materials. Published by Elsevier

Environmental Control System Installer/Servicer (Residential Air Conditioning Mechanic). V-TECS Guide.

ERIC Educational Resources Information Center

Meyer, Calvin F.; Benson, Robert T.

This guide provides job relevant tasks, performance objectives, performance guides, resources, learning activitites, evaluation standards, and achievement testing in the occupation of environmental control system installer/servicer (residential air conditioning mechanic). It is designed to be used with any chosen teaching method. The course…

Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

NASA Technical Reports Server (NTRS)

Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

1991-01-01

Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

Impact of the electric compressor for automotive air conditioning system on fuel consumption and performance analysis

NASA Astrophysics Data System (ADS)

Zulkifli, A. A.; Dahlan, A. A.; Zulkifli, A. H.; Nasution, H.; Aziz, A. A.; Perang, M. R. M.; Jamil, H. M.; Misseri, M. N.

2015-12-01

Air conditioning system is the biggest auxiliary load in a vehicle where the compressor consumed the largest. Problem with conventional compressor is the cooling capacity cannot be control directly to fulfill the demand of thermal load inside vehicle cabin. This study is conducted experimentally to analyze the difference of fuel usage and air conditioning performance between conventional compressor and electric compressor of the air conditioning system in automobile. The electric compressor is powered by the car battery in non-electric vehicle which the alternator will recharge the battery. The car is setup on a roller dynamometer and the vehicle speed is varied at 0, 30, 60, 90 and 110 km/h at cabin temperature of 25°C and internal heat load of 100 and 400 Watt. The results shows electric compressor has better fuel consumption and coefficient of performance compared to the conventional compressor.

Frequency-Unspecific Effects of θ-tACS Related to a Visuospatial Working Memory Task

PubMed Central

Kleinert, Maria-Lisa; Szymanski, Caroline; Müller, Viktor

2017-01-01

Working memory (WM) is crucial for intelligent cognitive functioning, and synchronization phenomena in the fronto-parietal network have been suggested as an underlying neural mechanism. In an attempt to provide causal evidence for this assumption, we applied transcranial alternating current stimulation (tACS) at theta frequency over fronto-parietal sites during a visuospatial match-to-sample (MtS) task. Depending on the stimulation protocol, i.e., in-phase, anti-phase or sham, we anticipated a differential impact of tACS on behavioral WM performance as well as on the EEG (electroencephalography) during resting state before and after stimulation. We hypothesized that in-phase tACS of the fronto-parietal theta network (stimulation frequency: 5 Hz; intensity: 1 mA peak-to-peak) would result in performance enhancement, whereas anti-phase tACS would cause performance impairment. Eighteen participants (nine female) received in-phase, anti-phase, and sham stimulation in balanced order. While being stimulated, subjects performed the MtS task, which varied in executive demand (two levels: low and high). EEG analysis of power peaks within the delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), and beta (12–30 Hz) frequency bands was carried out. No significant differences were observed between in-phase and anti-phase stimulation regarding both behavioral and EEG measurements. Yet, with regard to the alpha frequency band, we observed a statistically significant drop of peak power from pre to post in the sham condition, whereas alpha power remained on a similar level in the actively stimulated conditions. Our results indicate a frequency-unspecific modulation of neuronal oscillations by tACS. However, the closer participants’ individual theta peak frequencies were to the stimulation frequency of 5 Hz after anti-phase tACS, the faster they responded in the MtS task. This effect did not reach statistical significance during in-phase tACS and was not present during sham

New Composites LnBDC@AC and CB[6]@AC: From Design toward Selective Adsorption of Methylene Blue or Methyl Orange

PubMed Central

Santos, Guilherme de C.; Barros, Amanda L.; de Oliveira, Carlos A. F.; da Luz, Leonis L.; da Silva, Fausthon F.; Demets, Grégoire J.-F.; Alves Júnior, Severino

2017-01-01

New porous composites LnBDC@AC (AC = Activated carbon, Ln = Eu and Gd and BDC = 1,4-benzenedicaboxylate) and CB[6]@AC (CB[6] = Cucurbit[6]uril) were obtained using hydrothermal route. The LnBDC and CB[B] are located inside the pore of the carbon materials as was observed in SEM-EDS, XRPD and FT-IR analysis. Porosimetry analysis showed values typically between AC and LnBDC material, with pore size and surface area, respectively, 29,56 Å and 353.98 m2g-1 for LnBDC@AC and 35,53 Å and 353.98 m2g-1 for CB[6]@AC. Both materials showed good absorptive capacity of metil orange (MO) and methylene blue (MB) with selectivity as a function of pH. For acid pH, both materials present selectivity by MB and alkaline pH for MO, with notable performance for CB[6]@AC. Additionally, europium luminescence was used as structural probe to investigate the coordination environment of Eu3+ ions in the EuBDC@AC composite after adsorption experiment. PMID:28107440

Investigation of air cleaning system response to accident conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrae, R.W.; Bolstad, J.W.; Foster, R.D.

1980-01-01

Air cleaning system response to the stress of accident conditions are being investigated. A program overview and hghlight recent results of our investigation are presented. The program includes both analytical and experimental investigations. Computer codes for predicting effects of tornados, explosions, fires, and material transport are described. The test facilities used to obtain supportive experimental data to define structural integrity and confinement effectiveness of ventilation system components are described. Examples of experimental results for code verification, blower response to tornado transients, and filter response to tornado and explosion transients are reported.

Investigating performance of microchannel evaporators for automobile air conditioning with different port structures

NASA Astrophysics Data System (ADS)

Zhou, Guoliang; Su, Lin; Cheng, Qia; Wu, Longbing

2017-08-01

Microchannel evaporator has been widely applied in automobile air conditioning, while it faces the problem of refrigerant maldistribution which deteriorates the thermal performance of evaporator. In this study, the performances of microchannel evaporators with different port structures are experimentally investigated for purpose of reducing evaporator pressure drop. Four evaporator samples with different port number and hydraulic diameter are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant R-134A at a real automobile air conditioning. The results on the variations of the evaporator pressure drop and evaporator surface temperature distribution are presented and analyzed. By studying the performance of an evaporator, seeking proper port structure is an approach to reduce refrigerant pressure drop as well as improve refrigerant distribution.

21 CFR 886.1850 - AC-powered slitlamp biomicroscope.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered slitlamp biomicroscope. 886.1850... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1850 AC-powered slitlamp biomicroscope. (a) Identification. An AC-powered slitlamp biomicroscope is an AC-powered device that is a...

Influences of Cry1Ac broccoli on larval survival and oviposition of diamondback moth.

PubMed

Yi, Dengxia; Cui, Shusong; Yang, Limei; Fang, Zhiyuan; Liu, Yumei; Zhuang, Mu; Zhang, Yangyong

2015-01-01

Larval survival and oviposition behavior of three genotypes of diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), (homozygous Cry1Ac-susceptibile, Cry1Ac-resistant, and their F1 hybrids), on transgenic Bacillus thuringiensis (Bt) broccoli expressing different levels of Cry1Ac protein were evaluated in laboratory. These Bt broccoli lines were designated as relative low, medium, and high, respectively, according to the Cry1Ac content. Untransformed brocccoli plants were used as control. Larval survival of diamondback moth on non-Bt leaves was not significantly different among the three genotypes. The Cry1Ac-resistant larvae could survive on the low level of Bt broccoli plants, while Cry1Ac-susceptible and F1 larvae could not survive on them. The three genotypes of P. xylostella larvae could not survive on medium and high levels of Bt broccoli. In oviposition choice tests, there was no significant difference in the number of eggs laid by the three P. xylostella genotypes among different Bt broccoli plants. The development of Cry1Ac-susceptible and Cry1Ac-resistant P. xylostella on intact Bt plants was also tested in greenhouse. All susceptible P. xylostella larvae died on all Bt plants, while resistant larvae could survive on broccoli, which expresses low Cry1Ac protein under greenhouse conditions. The results of the greenhouse trials were similar to that of laboratory tests. This study indicated that high dose of Bt toxins in broccoli cultivars or germplasm lines is required for effective resistance management. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

A multicenter, randomized trial on neuroprotection with remote ischemic per-conditioning during acute ischemic stroke: the REmote iSchemic Conditioning in acUtE BRAin INfarction study protocol.

PubMed

Pico, Fernando; Rosso, Charlotte; Meseguer, Elena; Chadenat, Marie-Laure; Cattenoy, Amina; Aegerter, Philippe; Deltour, Sandrine; Yeung, Jennifer; Hosseini, Hassan; Lambert, Yves; Smadja, Didier; Samson, Yves; Amarenco, Pierre

2016-10-01

Rationale Remote ischemic per-conditioning-causing transient limb ischemia to induce ischemic tolerance in other organs-reduces final infarct size in animal stroke models. Aim To evaluate whether remote ischemic per-conditioning during acute ischemic stroke (<6 h) reduces brain infarct size at 24 h. Methods and design This study is being performed in five French hospitals using a prospective randomized open blinded end-point design. Adults with magnetic resonance imaging confirmed ischemic stroke within 6 h of symptom onset and clinical deficit of 5-25 according to National Institutes of Health Stroke Scale will be randomized 1:1 to remote ischemic per-conditioning or control (stratified by center and intravenous fibrinolysis use). Remote ischemic per-conditioning will consist of four cycles of electronic tourniquet inflation (5 min) and deflation (5 min) to a thigh within 6 h of symptom onset. Magnetic resonance imaging is repeated 24 h after stroke onset. Sample size estimates For a difference of 15 cm 3 in brain infarct growth between groups, 200 patients will be included for 5% significance and 80% power. Study outcomes The primary outcome will be the difference in brain infarct growth from baseline to 24 h in the intervention versus control groups (by diffusion-weighted image magnetic resonance imaging). Secondary outcomes include: National Institutes of Health Stroke Scale score absolute difference between baseline and 24 h, three-month modified Rankin score and daily living activities, mortality, and tolerance and side effects of remote ischemic per-conditioning. Discussion The only remote ischemic per-conditioning trial in humans with stroke did not show remote ischemic per-conditioning to be effective. REmote iSchemic Conditioning in acUtE BRAin INfarction, which has important design differences, should provide more information on the use of this intervention in patients with acute ischemic stroke.

Low-Flow Liquid Desiccant Air-Conditioning: Demonstrated Performance and Cost Implications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozubal, E.; Herrmann, L.; Deru, M.

2014-09-01

Cooling loads must be dramatically reduced when designing net-zero energy buildings or other highly efficient facilities. Advances in this area have focused primarily on reducing a building's sensible cooling loads by improving the envelope, integrating properly sized daylighting systems, adding exterior solar shading devices, and reducing internal heat gains. As sensible loads decrease, however, latent loads remain relatively constant, and thus become a greater fraction of the overall cooling requirement in highly efficient building designs, particularly in humid climates. This shift toward latent cooling is a challenge for heating, ventilation, and air-conditioning (HVAC) systems. Traditional systems typically dehumidify by firstmore » overcooling air below the dew-point temperature and then reheating it to an appropriate supply temperature, which requires an excessive amount of energy. Another dehumidification strategy incorporates solid desiccant rotors that remove water from air more efficiently; however, these systems are large and increase fan energy consumption due to the increased airside pressure drop of solid desiccant rotors. A third dehumidification strategy involves high flow liquid desiccant systems. These systems require a high maintenance separator to protect the air distribution system from corrosive desiccant droplet carryover and so are more commonly used in industrial applications and rarely in commercial buildings. Both solid desiccant systems and most high-flow liquid desiccant systems (if not internally cooled) add sensible energy which must later be removed to the air stream during dehumidification, through the release of sensible heat during the sorption process.« less

Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners

PubMed Central

Batterman, S.; Du, L.; Mentz, G.; Mukherjee, B.; Parker, E.; Godwin, C.; Chin, J.-Y.; O'Toole, A.; Robins, T.; Rowe, Z.; Lewis, T.

2014-01-01

This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84 ± 27%, but dropped to 63 ± 33% in subsequent seasons. In months when households were not visited, use averaged only 34 ± 30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. PMID:22145709

Transition to Low-GWP Alternatives in Passenger Vehicle Air Conditioners

EPA Pesticide Factsheets

This fact sheet provides current information on low global warming potential (GWP) alternatives in newly manufactured passenger vehicle air conditioners (ACs), in lieu of high-GWP hydrofluorocarbons (HFCs).

Trans-boundary air pollution in a city under various atmospheric conditions.

PubMed

Luo, Ming; Hou, Xiangting; Gu, Yefu; Lau, Ngar-Cheung; Yim, Steve Hung-Lam

2018-03-15

Trans-boundary air pollution (TAP) is a crucial factor affecting air quality, and its contribution may vary over time and differ under various atmospheric conditions. This study firstly applies an integrated statistical scheme to estimate the contributions of TAP and local sources to air pollutants in a city, and then investigate the influences of tropical cyclones (TC) on TAP. Hong Kong is chosen as an example because of its significant and special TAP characteristics. This study focuses on four major air pollutants, namely, respirable and fine suspended particulates (RSP/PM 10 and FSP/PM 2.5 ), sulfur dioxide (SO 2 ), and nitrogen dioxide (NO 2 ), from 2002 to 2013. Our results show that, on average, TAP is the major contributor of the annual RSP, FSP, SO 2 , and NO 2 in Hong Kong. We estimate that when a TC is approaching, the increase in pollutant concentration in Hong Kong is mainly due to the increase in TAP contribution by the strengthened northerly wind at higher level of atmosphere (≥900hPa). These changes are accompanied by decreases in precipitation and increases in northerly/north-easterly wind, which may prolong the lifetime of pollutants, enhancing pollutant transport from mainland China to Hong Kong. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of operational conditions on sludge degradation and organic acids formation in low-critical wet air oxidation.

PubMed

Chung, Jinwook; Lee, Mikyung; Ahn, Jaehwan; Bae, Wookeun; Lee, Yong-Woo; Shim, Hojae

2009-02-15

Wet air oxidation processes are to treat highly concentrated organic compounds including refractory materials, sludge, and night soil, and usually operated at supercritical water conditions of high temperature and pressure. In this study, the effects of operational conditions including temperature, pressure, and oxidant dose on sludge degradation and conversion into subsequent intermediates such as organic acids were investigated at low critical wet oxidation conditions. The reaction time and temperature in the wet air oxidation process was shown an important factor affecting the liquefaction of volatile solids, with more significant effect on the thermal hydrolysis reaction rather than the oxidation reaction. The degradation efficiency of sludge and the formation of organic acids were improved with longer reaction time and higher reaction temperature. For the sludge reduction and the organic acids formation under the wet air oxidation, the optimal conditions for reaction temperature, time, pressure, and oxidant dose were shown approximately 240 degrees C, 30min, 60atm, and 2.0L/min, respectively.

A problem of hospital hygiene: the presence of aspergilli in hospital wards with different air-conditioning features.

PubMed

Perdelli, Fernanda; Sartini, Marina; Spagnolo, Anna Maria; Dallera, Maurizio; Lombardi, Roberto; Cristina, Maria Luisa

2006-06-01

A total of 1,030 microbiological samples were taken in 3 hospital wards with different air-conditioning features: no conditioning system (ward A), a conditioning system equipped with minimum efficiency reporting value (MERV) filters (ward B), and a conditioning system thoroughly maintained and equipped with high-efficiency particulate air (HEPA) filters (absolute) (ward C). The air in each ward was sampled, and the bacterial and fungal concentrations were determined by active and passive methods. The concentration of fungi on surfaces was also determined. Active sampling showed positive samples in wards A and B only, with average values of 0.50 colony-forming units (CFU)/m(3) (95% CI, 0.30 to 0.70) in A and 0.16 CFU/m(3) (95% CI, 0.13 to 0.20) in B. Passive sampling was positive only in ward A (mean, 0.14 CFU/cm(2)/h; 95% CI, 0.13 to 0.15). Aspergillus was found in 27% and 22% of sampled surfaces in wards A and B, respectively, but in no samples from ward C. The most commonly found species was A. fumigatus (76% of cases in A and 34% of cases in B). The results show that the use of air-conditioning systems markedly reduces the concentration of aspergilli in the environment. Proper maintenance of these systems is clearly fundamental if their efficacy is to be ensured.

The investigation of an electric arc in the long cylindrical channel of the powerful high-voltage AC plasma torch

NASA Astrophysics Data System (ADS)

Rutberg, Ph G.; Popov, S. D.; Surov, A. V.; Serba, E. O.; Nakonechny, Gh V.; Spodobin, V. A.; Pavlov, A. V.; Surov, A. V.

2012-12-01

The comparison of conductivity obtained in experiments with calculated values is made in this paper. Powerful stationary plasma torches with prolonged period of continuous work are popular for modern plasmachemical applications. The maximum electrode lifetime with the minimum erosion can be reached while working on rather low currents. Meanwhile it is required to provide voltage arc drop for the high power achievement. Electric field strength in the arc column of the high-voltage plasma torch, using air as a plasma-forming gas, does not exceed 15 V/cm. It is possible to obtain the high voltage drop in the long arc stabilized in the channel by the intensive gas flow under given conditions. Models of high voltage plasma torches with rod electrodes with power up to 50 kW have been developed and investigated. The plasma torch arcs are burning in cylindrical channels. Present investigations are directed at studying the possibility of developing long arc plasma torches with higher power. The advantage of AC power supplies usage is the possibility of the loss minimization due to the reactive power compensation. The theoretical maximum of voltage arc drop for power supplies with inductive current limitations is about 50 % of the no-load voltage for a single-phase circuit and about 30 % for the three-phase circuit. Burning of intensively blown arcs in the long cylindrical channel using the AC power supply with 10 kV no-load voltage is experimentally investigated in the work. Voltage drops close to the maximum possible had been reached in the examined arcs in single-phase and three-phase modes. Operating parameters for single-phase mode were: current -30 A, voltage drop -5 kV, air flow rate 35 g/s; for three-phase mode: current (40-85) A, voltage drop (2.5-3.2) kV, air flow rate (60-100) g/s. Arc length in the installations exceeded 2 m.

The role of meteorological conditions and pollution control strategies in reducing air pollution in Beijing during APEC 2014 and Victory Parade 2015

NASA Astrophysics Data System (ADS)

Liang, Pengfei; Zhu, Tong; Fang, Yanhua; Li, Yingruo; Han, Yiqun; Wu, Yusheng; Hu, Min; Wang, Junxia

2017-11-01

To control severe air pollution in China, comprehensive pollution control strategies have been implemented throughout the country in recent years. To evaluate the effectiveness of these strategies, the influence of meteorological conditions on levels of air pollution needs to be determined. Using the intensive air pollution control strategies implemented during the Asia-Pacific Economic Cooperation Forum in 2014 (APEC 2014) and the 2015 China Victory Day Parade (Victory Parade 2015) as examples, we estimated the role of meteorological conditions and pollution control strategies in reducing air pollution levels in Beijing. Atmospheric particulate matter of aerodynamic diameter ≤ 2.5 µm (PM2.5) samples were collected and gaseous pollutants (SO2, NO, NOx, and O3) were measured online at a site in Peking University (PKU). To determine the influence of meteorological conditions on the levels of air pollution, we first compared the air pollutant concentrations during days with stable meteorological conditions. However, there were few days with stable meteorological conditions during the Victory Parade. As such, we were unable to estimate the level of emission reduction efforts during this period. Finally, a generalized linear regression model (GLM) based only on meteorological parameters was built to predict air pollutant concentrations, which could explain more than 70 % of the variation in air pollutant concentration levels, after incorporating the nonlinear relationships between certain meteorological parameters and the concentrations of air pollutants. Evaluation of the GLM performance revealed that the GLM, even based only on meteorological parameters, could be satisfactory to estimate the contribution of meteorological conditions in reducing air pollution and, hence, the contribution of control strategies in reducing air pollution. Using the GLM, we found that the meteorological conditions and pollution control strategies contributed 30 and 28 % to the reduction

In-Cabin Air Quality during Driving and Engine Idling in Air-Conditioned Private Vehicles in Hong Kong.

PubMed

Barnes, Natasha Maria; Ng, Tsz Wai; Ma, Kwok Keung; Lai, Ka Man

2018-03-27

Many people spend lengthy periods each day in enclosed vehicles in Hong Kong. However, comparably limited data is available about in-cabin air quality in air-conditioned private vehicles, and the car usage that may affect the air quality. Fifty-one vehicles were tested for particulate matter (PM 0.3 and PM 2.5 ), total volatile organic compounds (TVOCs), carbon monoxide (CO), carbon dioxide (CO₂), airborne bacteria, and fungi levels during their routine travel journey. Ten of these vehicles were further examined for PM 0.3 , PM 2.5 , TVOCs, CO, and CO₂ during engine idling. In general, during driving PM 2.5 levels in-cabin reduced overtime, but not PM 0.3 . For TVOCs, 24% vehicles exceeded the recommended Indoor Air Quality (IAQ) level in offices and public places set by the Hong Kong Environmental Protection Department. The total volatile organic compounds (TVOC) concentration positively correlated with the age of the vehicle. Carbon monoxide (CO) levels in all of the vehicles were lower than the IAQ recommendation, while 96% vehicles exceeded the recommended CO₂ level of 1000 ppmv; 16% vehicles >5000 ppmv. Microbial counts were relatively low. TVOCs levels at idle engine were higher than that during driving. Although the time we spend in vehicles is short, the potential exposure to high levels of pollutants should not be overlooked.

In-Cabin Air Quality during Driving and Engine Idling in Air-Conditioned Private Vehicles in Hong Kong

PubMed Central

Barnes, Natasha Maria; Ng, Tsz Wai; Ma, Kwok Keung; Lai, Ka Man

2018-01-01

Many people spend lengthy periods each day in enclosed vehicles in Hong Kong. However, comparably limited data is available about in-cabin air quality in air-conditioned private vehicles, and the car usage that may affect the air quality. Fifty-one vehicles were tested for particulate matter (PM0.3 and PM2.5), total volatile organic compounds (TVOCs), carbon monoxide (CO), carbon dioxide (CO2), airborne bacteria, and fungi levels during their routine travel journey. Ten of these vehicles were further examined for PM0.3, PM2.5, TVOCs, CO, and CO2 during engine idling. In general, during driving PM2.5 levels in-cabin reduced overtime, but not PM0.3. For TVOCs, 24% vehicles exceeded the recommended Indoor Air Quality (IAQ) level in offices and public places set by the Hong Kong Environmental Protection Department. The total volatile organic compounds (TVOC) concentration positively correlated with the age of the vehicle. Carbon monoxide (CO) levels in all of the vehicles were lower than the IAQ recommendation, while 96% vehicles exceeded the recommended CO2 level of 1000 ppmv; 16% vehicles >5000 ppmv. Microbial counts were relatively low. TVOCs levels at idle engine were higher than that during driving. Although the time we spend in vehicles is short, the potential exposure to high levels of pollutants should not be overlooked. PMID:29584686

Room air monitor for radioactive aerosols

DOEpatents

Balmer, David K.; Tyree, William H.

1989-04-11

A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-pre The U.S. Government has rights in this invention pursuant to Contract No. DE-AC04-76DP03533 between the Department of Energy and Rockwell International Corporation.

Subsurface Thermal Energy Storage for Improved Heating and Air Conditioning Efficiency

DTIC Science & Technology

2016-11-21

This project involved a field demonstration of subsurface thermal energy storage for improving the geothermal heat pump air conditioning efficiency... geothermal heat pump systems, undesirable heating of the ground may occur. This demonstration was performed at the MCAS, Beaufort, SC, where several...buildings with geothermal heat pump systems were exhibiting excessively high ground loop temperatures. These buildings were retrofitted with dry fluid

Air conditioning a vaccine laboratory. [Connaught Medical Research Laboratory, Toronto, Canada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross J.

1976-05-01

In 1974, the new Bacterial Vaccine Building of Connaught Medical Research Laboratories, Toronto, Canada, was opened to produce such vaccines as pertussis, typhoid, paratyphoids, and cholera and such toxoids as staphylococcus, diphtheria, and tetanus. It also produces other medicinal products. The layout of the complex and the air conditioning system necessary in all zones are described and schematically shown. (MCW)

Simulation of a solar-assisted absorption air conditioning system for applications in Puerto Rico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, A.Y.; Hernandez, H.R.; Gonzalez, J.E.

1995-11-01

Regions without conventional fuel sources have felt the need for the development of new technologies for air conditioning applications as cost of electrical energy production has continually risen the cost of air conditioning by conventional means. This paper deals with the simulation of a solar-assisted absorption system for air conditioning application in Puerto Rico. A simple thermodynamic model for the solar assisted absorption system has been developed. A solar energy based thermal storage system along with an auxiliary heater is used to provide the required energy in the generator of this absorption system. Results from a parametric analysis to studymore » the influence of the absorber, generator, condenser and evaporator temperatures, on the COP of the system are presented in this paper. The influence of two different refrigerant/absorbent pairs, water/lithium bromide and water/lithium-chloride have also been studied. A sub-system consisting of an array of flat plate solar collectors along with a hot water storage is modeled and verified with the data from an already existing system operating in Sacramento. Finally, off-design performance of a 35 kW solar-assisted absorption system is simulated to report the auxiliary heating requirement for a typical summer day operation in southern Puerto Rico.« less

TEWI Evaluation for Refrigeration and Air-Conditioning Systems in Office Buildings with Different Regional Heat Demand

NASA Astrophysics Data System (ADS)

Sobue, Atsushi; Watanabe, Koichi

In the present study, we quantitatively evaluated the global warming impact by refrigeration and air-conditioning systems in office buildings on the basis of reliable TEWI information. This paper proposes an improved TEWI evaluation procedure by considering regional heat demands and part load of air-conditioning systems. In the TEWI evaluation of commercial chillers, a percentage of the impact by refrigerant released to the atmosphere (direct effect) is less than 19.9% in TEWI values. Therefore, a reduction of the impact by CO2 released as a result of the energy consumed to drive the refrigeration or air-conditioning systems through out their lifetime (indirect effect) is the most effective measure in reducing the global warming impact. On the other hand, we have also pointed out energy loss that might be generated by an excess investment to the equipment. We have also showed a usefulness in dividing the heating / cooling system into several small-capacity units so as to improve the energy utilization efficiency.

Solar-powered air-conditioning

NASA Technical Reports Server (NTRS)

Clark, D. C.; Rousseau, J.

1977-01-01

Report focuses on recent study on development of solar-powered residential air conditioners and is based on selected literature through 1975. Its purposes are to characterize thermal and mechanical systems that might be useful in development of Rankine-cycle approach to solar cooling and assessment of a Lithium Bromide/Water absorption cycle system.

Fault tree analysis for exposure to refrigerants used for automotive air conditioning in the United States.

PubMed

Jetter, J J; Forte, R; Rubenstein, R

2001-02-01

A fault tree analysis was used to estimate the number of refrigerant exposures of automotive service technicians and vehicle occupants in the United States. Exposures of service technicians can occur when service equipment or automotive air-conditioning systems leak during servicing. The number of refrigerant exposures of service technicians was estimated to be 135,000 per year. Exposures of vehicle occupants can occur when refrigerant enters passenger compartments due to sudden leaks in air-conditioning systems, leaks following servicing, or leaks caused by collisions. The total number of exposures of vehicle occupants was estimated to be 3,600 per year. The largest number of exposures of vehicle occupants was estimated for leaks caused by collisions, and the second largest number of exposures was estimated for leaks following servicing. Estimates used in the fault tree analysis were based on a survey of automotive air-conditioning service shops, the best available data from the literature, and the engineering judgement of the authors and expert reviewers from the Society of Automotive Engineers Interior Climate Control Standards Committee. Exposure concentrations and durations were estimated and compared with toxicity data for refrigerants currently used in automotive air conditioners. Uncertainty was high for the estimated numbers of exposures, exposure concentrations, and exposure durations. Uncertainty could be reduced in the future by conducting more extensive surveys, measurements of refrigerant concentrations, and exposure monitoring. Nevertheless, the analysis indicated that the risk of exposure of service technicians and vehicle occupants is significant, and it is recommended that no refrigerant that is substantially more toxic than currently available substitutes be accepted for use in vehicle air-conditioning systems, absent a means of mitigating exposure.

High-Frequency ac Power-Distribution System

NASA Technical Reports Server (NTRS)

Hansen, Irving G.; Mildice, James

1987-01-01

Loads managed automatically under cycle-by-cycle control. 440-V rms, 20-kHz ac power system developed. System flexible, versatile, and "transparent" to user equipment, while maintaining high efficiency and low weight. Electrical source, from dc to 2,200-Hz ac converted to 440-V rms, 20-kHz, single-phase ac. Power distributed through low-inductance cables. Output power either dc or variable ac. Energy transferred per cycle reduced by factor of 50. Number of parts reduced by factor of about 5 and power loss reduced by two-thirds. Factors result in increased reliability and reduced costs. Used in any power-distribution system requiring high efficiency, high reliability, low weight, and flexibility to handle variety of sources and loads.

75 FR 6338 - Protection of Stratospheric Ozone: New Substitute in the Motor Vehicle Air Conditioning Sector...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-09

... document, EPA proposed to find HFO-1234yf acceptable as an alternative refrigerant for motor vehicle air conditioning, subject to use conditions. The refrigerant discussed in the proposed action, for which the...

Tourists’ attitudes towards ban on smoking in air-conditioned hotel lobbies in Thailand

PubMed Central

Viriyachaiyo, V; Lim, A

2009-01-01

Background: Thailand is internationally renowned for its stringent tobacco control measures. In Thailand, a regulation banning smoking in air-conditioned hotel lobbies was issued in late 2006, causing substantial apprehension within the hospitality industry. A survey of tourists’ attitudes toward the ban was conducted. Methods: A cross-sectional survey of 5550 travellers staying in various hotels in Bangkok, Surat Thani, Phuket, Krabi and Songkhla provinces, October 2005 to December 2006. Travellers aged 15 years or older with a check-in duration of at least one day and willing to complete the questionnaire were requested by hotel staff to fill in the 5-minute questionnaire at check-in or later at their convenience. Results: Secondhand cigarette smoke was recognised as harmful to health by 89.7% of respondents. 47.8% of travellers were aware of the Thai regulation banning smoking in air-conditioned restaurants. 80.9% of the respondents agreed with the ban, particularly female non-smokers. 38.6% of survey respondents indicated that they would be more likely to visit Thailand again because of the regulation, 53.4% that the regulation would not affect their decision and 7.9% that they would be less likely to visit Thailand again. Conclusion: Banning smoking in air-conditioned hotel lobbies in Thailand is widely supported by tourists. Enforcement of the regulation is more likely to attract tourists than dissuade them from holidaying in Thailand. PMID:19364754

78 FR 39345 - ACS Wireless, Inc.; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-01

... on July 31, 1995 under the name MACTEL INC. Alaska Communications Systems Group, Inc. (``ACS Group...-owned subsidiary of ACS Group, held through ACS Group's wholly-owned subsidiary Alaska Communications... presently an investment company as defined in section 3(a) of the Act. 2. On June 4, 2012, ACS Group, ACS...

Non-Print Instructional Materials for the Air Conditioning and Refrigeration Maintenance Field.

ERIC Educational Resources Information Center

Golitko, Raymond L., Ed.; And Others

This catalog contains a listing of air conditioning/refrigeration maintenance audiovisual training materials from the Houston Community College System library media collection. The material is organized by subject heading. The media titles are listed in alphabetical order by title under each subject heading in the catalog. The citation for each…

A-C Estrogens as Potent and Selective Estrogen Receptor-Beta Agonists (SERBAs) to Enhance Memory Consolidation under Low-Estrogen Conditions.

PubMed

Hanson, Alicia M; Perera, K L Iresha Sampathi; Kim, Jaekyoon; Pandey, Rajesh K; Sweeney, Noreena; Lu, Xingyun; Imhoff, Andrea; Mackinnon, Alexander Craig; Wargolet, Adam J; Van Hart, Rochelle M; Frick, Karyn M; Donaldson, William A; Sem, Daniel S

2018-06-14

Estrogen receptor-beta (ERβ) is a drug target for memory consolidation in postmenopausal women. Herein is reported a series of potent and selective ERβ agonists (SERBAs) with in vivo efficacy that are A-C estrogens, lacking the B and D estrogen rings. The most potent and selective A-C estrogen is selective for activating ER relative to seven other nuclear hormone receptors, with a surprising 750-fold selectivity for the β over α isoform and with EC 50 s of 20-30 nM in cell-based and direct binding assays. Comparison of potency in different assays suggests that the ER isoform selectivity is related to the compound's ability to drive the productive conformational change needed to activate transcription. The compound also shows in vivo efficacy after microinfusion into the dorsal hippocampus and after intraperitoneal injection (0.5 mg/kg) or oral gavage (0.5 mg/kg). This simple yet novel A-C estrogen is selective, brain penetrant, and facilitates memory consolidation.

The mechanism of detection of air pollution by an ionization chamber.

PubMed

Novković, D; Vukanac; Milosević, Z

2000-01-01

The mechanism of detection of chemical vapors in air by an ionization chamber supplied by DC and AC voltage has been described. The theoretical explanation is based on numerical solutions of the differential equations of the cylindrical ionization chamber. The current of the ionization chamber operating in the AC regime has two components: a conductive component, caused by the ions drifts, and a capacitive component, caused by the distortion of the electric field. The ionization chamber operating in the DC regime has only the first component; hence the AC supplied chamber has larger response than the DC supplied chamber.

Hypertension prevalence and living conditions related to air pollution: results of a national epidemiological study in Lebanon.

PubMed

Salameh, Pascale; Chahine, Mirna; Hallit, Souheil; Farah, Rita; Zeidan, Rouba Karen; Asmar, Roland; Hosseiny, Hassan

2018-04-01

Hypertension is a risk factor of several diseases, linked to high mortality and morbidity, particularly in developing countries. Some studies have linked indoor and outdoor pollution exposure items to hypertension, but results were inconsistent. Our objective was to assess the association of living conditions related to air pollution to hypertension in Lebanon, a Middle Eastern country. A national cross-sectional study was conducted all over Lebanon. Blood pressure and its related medications were assessed to be able to classify participants as hypertensive or not. Moreover, in addition to living conditions related to air pollution exposure, we assessed potential predictors of hypertension, including sociodemographic characteristics, self-reported health information and biological measurements. Furthermore, we assessed dose-effect relationship of air pollution items in relation with hypertension. Living conditions related to indoor and outdoor air pollution exposures were associated with hypertension, with or without taking biological values into account. Moreover, we found a dose-effect relationship of exposure with risk of disease (15% increase in risk of disease for every additional pollution exposure item), after adjustment for sociodemographics and biological characteristics (Ora = 1.15 [1.03-1.28]). Although additional studies would be necessary to confirm these findings, interventions should start to sensitize the population about the effect of air pollution on chronic diseases. The work on reducing pollution and improving air quality should be implemented to decrease the disease burden on the population and health system.

NREL's Energy-Saving Technology for Air Conditioning Cuts Peak Power Loads Without Using Harmful Refrigerants (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2012-07-01

This fact sheet describes how the DEVAP air conditioner was invented, explains how the technology works, and why it won an R&D 100 Award. Desiccant-enhanced evaporative (DEVAP) air-conditioning will provide superior comfort for commercial buildings in any climate at a small fraction of the electricity costs of conventional air-conditioning equipment, releasing far less carbon dioxide and cutting costly peak electrical demand by an estimated 80%. Air conditioning currently consumes about 15% of the electricity generated in the United States and is a major contributor to peak electrical demand on hot summer days, which can lead to escalating power costs, brownouts,more » and rolling blackouts. DEVAP employs an innovative combination of air-cooling technologies to reduce energy use by up to 81%. DEVAP also shifts most of the energy needs to thermal energy sources, reducing annual electricity use by up to 90%. In doing so, DEVAP is estimated to cut peak electrical demand by nearly 80% in all climates. Widespread use of this cooling cycle would dramatically cut peak electrical loads throughout the country, saving billions of dollars in investments and operating costs for our nation's electrical utilities. Water is already used as a refrigerant in evaporative coolers, a common and widely used energy-saving technology for arid regions. The technology cools incoming hot, dry air by evaporating water into it. The energy absorbed by the water as it evaporates, known as the latent heat of vaporization, cools the air while humidifying it. However, evaporative coolers only function when the air is dry, and they deliver humid air that can lower the comfort level for building occupants. And even many dry climates like Phoenix, Arizona, have a humid season when evaporative cooling won't work well. DEVAP extends the applicability of evaporative cooling by first using a liquid desiccant-a water-absorbing material-to dry the air. The dry air is then passed to an indirect

AC conductivity and dielectric behavior of bulk Furfurylidenemalononitrile