The energy and exergy of low-global warming potential (GWP) refrigerants were investigated experimentally and theoretically. Refrigerants with a modest GWP100 of ≤ 150 can be sufficient for bringing down emissions which were concerned for the automotive air-conditioning system. Three types of low-GWP refrigerants, R152a, R1234yf, and R1234ze(E), were examined with particular reference to the current high-GWP of R134a. The effect of different evaporating and condensing temperatures in addition to compressor speed was considered. The purpose was to bring a clear view of the performance characteristics of possible environment friendly alternatives of R134a. The analysis was carried out with compressor power, cooling capacity, coefficient of performance, exergy destruction, and exergy efficiency. It was noted that the total exergy destruction of R1234yf was reduced by 15% compared to that of R134a. The refrigerant R1234ze(E) has the highest energetic and exergetic performance compared with the other investigated refrigerants.
In this work, an experimental study is conducted on the performance of heat pipes heat exchanger for the application of heat recovery in air conditioning. To carry out this work, a heat pipe heat exchanger is installed between fresh air and return air to cool the fresh air. Three test sections were used with different inner pipe diameters of 7.9, 10.2 and 16.56 mm. The fresh air inlet temperature was changed to be 30 ºC, 35 ºC, 40 ºC, 45 ºC and 50 ºC in order to simulate the change of ambient temperature. The ratio between cooled and fresh air was chosen to be 1, 1.5, 2 and 3. The results obtained indicated that the effectiveness of the heat pipe heat exchangers increases with both of the increase of fresh air inlet temperature and the ratio between cooled and fresh air.
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