Indoor Environment and Energy Performance of Office Buildings Equipped with a Low Temperature Heating / High Temperature Cooling System

2014 ◽  
Vol 899 ◽  
pp. 36-41 ◽  
Author(s):  
Dušan Petráš ◽  
Michal Krajčík ◽  
Jozef Bugáň ◽  
Emília Ďurišová
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Indoor Environment ◽  
Cooling System ◽  
Energy Performance ◽  
Heat Pumps ◽  
Office Buildings ◽  
Cooling Systems ◽  
Temperature Heating

Energy performance and indoor environment were investigated in two modern office buildings equipped by a low temperature heating and high temperature cooling system. Both buildings have the facade made of glass. In the first building, radiant panels are suspended under the ceiling in order to create comfortable conditions, natural gas boilers are the installed in order to generate heat and chillers are used to generate cool. The second building has heat pumps installed to provide the building with heat/cool and capillary pipes are embedded in the plaster on the ceiling surface to emit the heat/cool into the occupied space. The energy performance was calculated in accordance with the set of CEN standards for energy certification and is presented in the form of energy certificates. Thermal comfort and indoor air quality were experimentally studied by long-term and short-term measurements and through questionnaires filled in by the occupants themselves. The study has shown that the low temperature heating/high temperature cooling system has the potential to create a comfortable indoor environment at low energy consumption, but the ability of the heating/cooling systems to do so is closely related to the appropriate control of the systems.

Relieving of Residual Stresses in Metal Workpieces at High and Low Temperatures

2021 ◽  
Vol 887 ◽  
pp. 651-656
Author(s):  
Marina V. Polonik
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Low Temperatures ◽  
Creep Properties ◽  
Processing Modes ◽  
Properties Of Materials ◽  
High And Low Temperatures ◽  
Temperature Heating ◽  
High Temperature Heating

On the basis of previously accumulated irreversible deformations, and, consequently, residual stresses, the process of removing residual stresses in metal workpieces under the action of low and high temperatures is simulated. Boundary value problems are solved and here are described regularities that are responsible for removing residual stresses for processing modes: high-temperature heating - cooling, high-temperature heating - holding - cooling, low-temperature heating - holding - cooling. The holding stage is modeled, taking into account the creep properties of materials under Norton creep conditions. According to the dependences of the obtained exact solutions, it is shown that it is the holding process that leads to the relaxation of residual stresses.

scholarly journals System Design of Electricity Generation Using Waste Heat from LNG Automobile

2020 ◽  
Vol 145 ◽  
pp. 02062
Author(s):  
Canzong Zhou ◽  
Shuyi Chen ◽  
Wei Cui ◽  
Zhengmao Yao
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Electricity Generation ◽  
Waste Heat ◽  
Cooling System ◽  
Combustion Engine ◽  
Lead Telluride ◽  
Maximum Output ◽  
Thermoelectric Conversion ◽  
Temperature Environment

According to the research, thermoelectricity generation can recycle the heat contained in the cooling system of internal combustion engine. This paper is about taking advantage of the feature in the huge temperature difference at about 560 °C which is formed between high-temperature engine and LNG (Liquefied Natural Gas) in low temperature and the ability that LNG provides semiconductor with thermoelectric conversion material so as to produce the maximum output voltage in low temperature. We take advantage of lead telluride materials that adapt to the high temperature environment and bismuth telluride materials that adapt to the low temperature environment, both of which forms a circuit and are designed as a thermoelectric power generation device. Also, we confirm the possibility of applying the device to cars.

IEA EBC Annex 59: High temperature cooling and low temperature heating in buildings

2017 ◽  
Vol 145 ◽  
pp. 267-275 ◽  
Author(s):  
Xiaohua Liu ◽  
Tao Zhang ◽  
Haida Tang ◽  
Yi Jiang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Heating

Review Status on High Temperature Heat Pumps

2012 ◽  
Vol 170-173 ◽  
pp. 2550-2553 ◽  
Author(s):  
Guang Hui Zhou ◽  
Shi Wei Feng ◽  
Si Qi Cui ◽  
Yin Liu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Heat Pump ◽  
Heat Pumps ◽  
Industrial Processes ◽  
Paper Briefly ◽  
Development Status ◽  
Temperature Heat ◽  
Waste Energy ◽  
Higher Temperature

A heat pump is a kind of energy saving equipment. It can effectively improve the grade of low temperature renewable and waste energy. Because of the increasing demands for higher temperature energy in many industrial processes and other fields, the development and research of high temperature heat pumps have been becoming more and more pressing and significant. This paper briefly summarizes the development status in two aspects: the development of working fluids and system features and characteristics of different cycle types.

scholarly journals EFFECTS OF LONG-TERM RELATIVELY HIGH AND LOW TEMPERATURE USE ON GROWTH PERFORMANCE AND MEAT QUALITY OF BROILERS

2020 ◽  
pp. 12-17
Author(s):  
Yingying Qiao ◽  
Oleksandr Kyselov ◽  
Changzhong Liu
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Growth Performance ◽  
Meat Quality ◽  
Low Temperatures ◽  
Production Performance ◽  
Control Group ◽  
Temperature Group

The experiment aims to study the effects of long-term relatively high and low temperatures on growth performance and meat quality of broiler chickens. The experiment was carried out in Yunnan Academy of Animal Science, for determine the quality of meat used the laboratories of Henan Institute of Science and Technology. A total of experiment use 240 healthy 1-day-old Avian broiler chickens were randomly divided into three groups: relatively high temperature group, low temperature group and control group. The results of the experiment confirm that at low temperatures, when the energy consumption of the animal decreases, it leads to weight loss, which we can see in the low-temperature group, the average daily weight gain in this experiment was significantly lower than in the control group (P <0.05). It was found that low-temperature stress significantly increased the mortality of broilers, at the age of 42 days in the low-temperature group, the mortality of chickens was higher than in the control group, by 71.4%. Among all evaluated groups on the content of unsaturated fatty acids SFA, PUFA, MUFA and EFA in the muscles of the breasts of broilers, the lowest content was in the lower temperature group than in the control group, by 48.3%, 46.9%, 51.5% and 43.9%. Studies have shown that influence of high-temperature above 30°C causes disturbances in poultry behavior and physiology, leading to reduced production performance. Broilers aged 35-40 days experienced 31°C high-temperature stress and found that their performance and immunity decreased. Broilers feed intake and growth rate at 35°C high temperature were reduced by 13% and 32% than at 20°C. The results showed that: ① Relatively high temperature and low temperature for a long time reduced the growth performance and mortality of broilers, and long-term relatively low temperature decreased the slaughter performance of broilers.② Relatively high and low temperatures for a long period of time reduced the levels of serine, glycine, SFA, PUFA, USFA, EFA and MUFA in broiler breast muscles negative effect on meat quality. ③ The long-term relatively low temperature has a greater adverse effect on broilers than the long-term relatively high temperature. The results provided some theoretical basis for accurately setting the broiler breeding environment temperature, improving broiler quality, maximizing broiler production performance, and increasing the economic benefits of the farm.

Self-Propelling Cooling Systems: Back-Fitting Passive Cooling Functions to Existing Nuclear Power Plants

2012 ◽  
Author(s):  
Dominik von Lavante ◽  
Dietmar Kuhn ◽  
Ernst von Lavante
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Cooling System ◽  
Electrical Power ◽  
Reactor Core ◽  
Passive Cooling ◽  
Spent Fuel ◽  
Cooling Systems ◽  
Spent Fuel Pool

The present paper describes a back-fit solution proposed by RWE Technology GmbH for adding passive cooling functions to existing nuclear power plants. The Fukushima accidents have high-lighted the need for managing station black-out events and coping with the complete loss of the ultimate heat sink for long time durations, combined with the unavailability of adequate off-site supplies and adequate emergency personnel for days. In an ideal world, a nuclear power plant should be able to sustain its essential cooling functions, i.e. preventing degradation of core and spent fuel pool inventories, following a reactor trip in complete autarchy for a nearly indefinite amount of time. RWE Technology is currently investigating a back-fit solution involving “self-propelling” cooling systems that deliver exactly this long term autarchy. The cooling system utilizes the temperature difference between the hotter reactor core or spent fuel pond with the surrounding ultimate heat sink (ambient air) to drive its coolant like a classical heat machine. The cooling loop itself is the heat machine, but its sole purpose is to merely achieve sufficient thermal efficiency to drive itself and to establish convective cooling (∼2% thermal efficiency). This is realized by the use of a Joule/Brayton Cycle employing supercritical CO2. The special properties of supercritical CO2 are essential for this system to be practicable. Above a temperature of 30.97°C and a pressure of 73.7bar CO2 becomes a super dense gas with densities similar to that of a typical liquid (∼400kg/m3), viscosities similar tothat of a gas (∼3×105Pas) and gas like compressibility. This allows for an extremely compact cooling system that can drive itself on very small temperature differences. The presented parametric studies show that a back-fitable system for long-term spent fuel pool cooling is viable to deliver excess electrical power for emergency systems of approximately 100kW. In temperate climates with peak air temperatures of up to 35°C, the system can power itself and its air coolers at spent fuel pool temperatures of 85°C, although with little excess electrical power left. Different back-fit strategies for PWR and BWR reactor core decay heat removal are discussed and the size of piping, heat exchangers and turbo-machinery are briefly evaluated. It was found that depending on the strategy, a cooling system capable of removing all decay heat from a reactor core would employ piping diameters between 100–150mm and the investigated compact and sealed turbine-alternator-compressor unit would be sufficiently small to be integrated into the piping.

scholarly journals High Temperature Cooling and Low Temperature Heating in Buildings of EBC Annex 59

2015 ◽  
Vol 78 ◽  
pp. 2433-2438 ◽  
Author(s):  
Yi Jiang ◽  
Xiaohua Liu ◽  
Lun Zhang ◽  
Tao Zhang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Heating

scholarly journals Environmental tests of vapor compression heat pump for space applications

2020 ◽  
pp. 240-240
Author(s):  
Xudong Ma ◽  
Rui Ma ◽  
Yilin Ye ◽  
Suying Yan ◽  
Feng Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Heat Pump ◽  
Low Temperatures ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Space Applications ◽  
Suitable Temperature ◽  
High And Low Temperatures

Heat pumps are needed to provide a suitable temperature for both people and equipment in spacecraft. This paper reports on work designed to see if vapor compression heat pumps, in particular, can be expected to function normally in space. A vapor compression heat pump was built and tested under conditions of high temperature (70?C), low temperature (0?C), and near-vacuum (10-4 Pa). It was found that the coefficient of performance of this heat pump was 2.99 at both high and low temperatures, and was 2.1 under near vacuum conditions. The results suggest that vapor compression heat pumps are suitable for use in space.

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