Study On Refrigerant Charge Of Microchannle Heat Exchanger Used In Residential Split-type Air Conditioner

According to the new stronger Montreal Protocol, the countries in clouse 5 should freeze the production and consumption as the base line leval(average of 2009&2010 levels) in 2013, and reduction 10% in 2015. As the one of the main consumption of HCFC, the refrigerant replacement for domestic air-conditioning industry is extremely urgent. As recognized, hydrocarbon refrigerents is environmental friendly, they not only have no damage to the ozone, but also nearly have no negative effect to the climate. What’s more, they have perfect energy saving potential. But the application of hydrocarbon refrigerants is limited by its flammability. To solve the problem, the key issue is to reduce the refrigerant charge of air conditioning system. As the most part of refrigerant of the system are in the heat exchangers, the using of microchannel heat exchanger in air conditioning system to replace the origin tube-fin heat exchanger is one of the most important methods to reduce the refrigerant charge.Besides, as the government enhance energy efficiency standards of air conditioning system and the price of copper keep increasing, the research about the application of microchannel heat exchanger in domestic air conditioning system is increased in recent years.The main contents and results of the paper are as follows: 1). Microchannel hrat exchanger model is eatablished to study the influence of key parameters of microchannel heat exchanger, such as fin pitch, fin height, the louver angle, etc, on system performance. It also give guidance to the design of microchannel heat exchangers. 2). Experimently researched the ways to decrease to refrigerant charge of the system. In 3HP packaged air conditioner, the refrigerant charge of R290 can be deceased to 470 g by using flat of smaller width, while the capacity of the new system decreased by 8.9% than the original one while the COP increased by 14.8%. In 1.5HP split air conditioner, the refrigerant charge of R290 can be deceased to 280 g by using header with an inner diameter of 11 mm. Through the special connection method between headers and flat tubes, the inner diameter of the header can be reduced to 6mm. The R290 charge of the new heat exchanger system was reduced to 190 g. 3). Experimentally studied about the effect of fin pitch of indoor microchannel heat exchanger on its drainage ability and system performance on 3HP packaged air conditioner. After exchanging the optimized indoor microchannel heat exchanger, the refrigerant charge for the system reduced 15.9%. Meanwhile, the cooling capacity of the new system was 1% lower than the original system while the COP was 2.2% higher; the heating capacity of the new system was 3.9% higher than the original one while the COP was 11.2% higher. 4). Experimently studied the MCHX sample with better drainage ability. The result shows through it has better performance in cooling mode, it still has drainage problem in heating mode. The reason is producing process and the small angle between louver fins.