22 May 2002

B3-07 Study on intelligent defrost time of air-cooled heat pump

Air-Cooled heat pumps have numerous advantages in many applications over other heating equipment with regard to energy efficiency, operation, and safety. However, some problems are accompanied with it in winter, such as heating capacity decreasing, too much low pressure protecting, compressor damaging, and so on.
After investigation and analyses, it is found that the unsuitable defrost control is the key reason. Now, most heat pumps have temperature-time controller, and can’t adapt to different areas because of different weather conditions. For lack of details of the climates, the manufactory’s field test and modulation is not available. In order to overcome this problem, intelligent defrosting is dead in need.
In this paper, the reasons causing unreliable running of air-cooled heat pump in winter are firstly analyzed and then some improvements are discussed. At last, the research and development of intelligent defrost control is given in detail. Simulation results show that the fuzzy controller is a very effective way to improve the performance of air-cooled heat pump in winter.