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RISS 인기검색어
- 검색키워드
- 저자 : Abd-Elhady M. S. (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Increasing the Cooling Rate of the Vapor Compression Cycle by Heating
M. S. Abd-Elhady,E. Bishara,M. A. Halim 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.1
Refrigeration and air conditioning cycles consume a large amount of electrical energy and the shortage in traditional sources of energy is the main reasons for governments to use renewable energy. The most power consuming part in the Vapor Compression Cycle (VCC) is the gas compressor. Therefore, the objective of this research is to increase the cooling rate of the VCC using the same compressor, and that is done by heating the refrigerant coming out from the compressor. The proposed cycle is similar to the VCC except that the compression processes is done in two stages, the first stage via a gas compressor and in the second stage by heating the refrigerant under constant volume. The heating process can be done using solar energy. An experimental setup has been developed to study the influence of heating the refrigerant on the cooling rate of the VCC. The heating process is performed after the compressor, and it is done under constant volume in order to increase the pressure of the refrigerant. Four experiments have been performed; the first experiment is a normal VCC, i.e., without heating, while in the second, third and fourth experiments, the refrigerant has been heated to 50°C, 100°C and 150°C, respectively. It has been found that the cooling power increases with the heating temperature. Heating increases the pressure of the refrigerant in VCC, and consequently increases the mass flow rate of the refrigerant that results in an increase in the refrigeration power for the same compressor power. However, the disadvantage of heating the refrigerant is that it increases the evaporator temperature, which limits the possibility of the VCC to be used in freezing applications.
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A Novel Technique for Improving the Performance of Ammonia Absorption Refrigeration Cycle
Hemeda Shaker M.,Abd-Elhady M. S.,Halim M. A. 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.1
The world is now living in an energy crisis. Refrigeration and air-conditioning systems have become the basics of daily life in various fields and accordingly, it cannot be dispensed. Refrigeration machines and air-conditioning systems are the most energy-consuming systems, independent on the application whether it is domestic, commercial, industrial or medical. Therefore, using cooling systems which are powered by thermal energy, e.g., solar energy, can save a lot of electrical energy. Absorption refrigeration system is an example of a refrigeration system powered by heat energy. However, the system problem here is that it has low coefficient of performance (COP). The objective of this research is to improve the COP of the ammonia absorption cycle. This is done in the absorber unit by improving the absorption of the refrigerant ammonia into the ammonia–water solution. The absorption efficiency is improved by using (1) a stirrer pump to improve mixing, (2) sprayers to increase the contact area between ammonia and ammonia–water solution and (3) continuous cooling of the solution during the absorption process via an external heat exchanger. The COP of the ammonia absorption cycle has increased from 0.48 to 0.715, i.e., by 49%. This is due to the improvement of the absorption of the ammonia into the ammonia–water solution.
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