الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In recent years, the economy becomes important concern in the researches of
the whole world. This interest involves decreasing the cost of materials used in manufacturing, energy consumption and others. Besides, many researches have been focused in the recent years towards the protection of the environment. One of the important studies is developing the air conditioning systems since its use
increased because of the unsuitable weather during most time of the year. In this work the use of microchannel condenser (MChC) instead of finned tube condenser (FTC) in the air conditioning units has been studied. The main objective of this study is to experimentally investigate the effect of this new technology on the
performance of refrigeration unit that utilizes the microchannel condenser
(MCHC) in comparison with the unit that utilizes traditional round tube-finned
condenser. The study was conducted at different outdoor temperature and different capacity size of air conditioning unit. The tests were taken at steady state condition
and according to British standard ISO 5151, Egyptian standard ES: 4818-2005 and (JIS C9612).
The study was conducted on four Split air conditioning units utilize R-22 as
a refrigerant. The units were divided into two groups; the first group was two units having capacity of 3516 W. One of them was supplied by FTC while the second one was equipped with michrochannel condenser. The second group was two units of cooling capacity of 5274 W with the same two different types condenser. The indoor and outdoor units were installed in air conditioned rooms in order to perform the tests at different operating conditions. The study involved the effect of ambient temperature on : the condenser outlet air temperature, discharge pipe temperature, mass flow rate, condenser pressure drop, inside convective heat
transfer coefficient, outside convective heat transfer coefficient, overall heat transfer coefficients, actual cooling capacity, compressor current and power consumption, and condenser energy efficiency ratio EER.
Through this work the use of michrochannel condenser achieves a decrease in using refrigerant charge which reflected on the unit cost and also protection of the environment from pollution. The obtained results indicated that, the use of michrochannel condenser decreases the power input by amount of (1.4: 3.6 %) for the first unit and (12.9:17.5 %) for the second unit.
The value of EER for the systems (3516 W and 5274 W) with the microchannel condenser was improved by (4.3: 11.3 % and 9.47: 29 %) than that with the finned tube condenser respectively. The cooling capacity of the unit is
decreased for the two cases with the increase of ambient temperature. However, the decreasing rate for the case of using MChC is lower than that for the case of using FTC. The actual power consumed by the unit is lower for the case of using MChC than that consumed by the traditional unit and consequently the value of
EER higher. The pressure DROP was decreased when microchannel condenser was used by around (20:30%), due to the increase in the cross sectional area of the refrigerant flow and the shorter refrigerant flow distance.
The use of michrochannel condenser instead of finned tube condenser leads
to increase the convective heat transfer coefficient by (205:211%). The overall heat transfer coefficient by (61.6:84.1%) for the unit 5274 than that in the case of using finned tube condenser [FTC].