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In the recent years, many researches have been focused towards the new technology in heat exchangers. Besides, the economy of manufacturing takes up a great attention of scientific works. Through this work the use of microchannel condenser achieves increase in energy. The study was conducted on two air conditioning units utilize R-22 as a refrigerant and having different cooling capacities 3516 W and 5274 W. The results showed that the use of microchannel condenser achieves increase in Energy Efficiency Ratio (EER) which reflected on the total efficiency of the device and reduce energy cost. The obtained results indicated that, the use of microchannel condenser led to increase in EER by (4.3:11.3%) for the first unit and and (9.5:29%) for the second one compared with that unit use FTC. Also, the use of MChC led to decrease the pressure drop by (20%:30%) while the convective heat transfer coefficient is improved by (61.6:84.1%).

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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.

Air curtains are devices used in refrigerated display cabinets and the entrance of air conditioned spaces is aimed to reduce the breakthrough of heat, moisture and contaminants between the conditioned environment and the surrounding ambient, consequently reducing energy costs. The main objective of the present work is to study the parameter affecting the performance of air curtains used in viewer refrigerators using one and two air curtains at different ambient conditions, in order to reduce the air infiltration and consequently the energy consumption. The results of one and two air curtains are compared, where two air curtains are more effective than one air curtain