22 May 2008

A NOVEL PCM BASED REVERSE CYCLE DEFROSTING METHOD FOR AIR SOURCE HEAT PUMPS


The most widely used standard defrosting method for air source heat pumps
(ASHPs) is reverse cycle defrosting. However, the fundamental problem of this method is
that there is insufficient heat available during defrosting. This consequently leads to a poorer
operating performance, reduced indoor thermal comfort for occupants and a poorer system
reliability, etc. In order to solve this problem of insufficient heat and a number of its
associated operational problems, in the paper a novel thermal energy storage (TES) based
reverse cycle defrosting method for ASHPs using phase change material (PCM) was
presented. The schematics, operation modes and control strategy of ASHP using the TES
defrosting method developed were introduced. The experimental results indicated that the
novel reverse defrosting method solve a number of problems including a longer defrosting
time and a poorer system reliability and etc. existing in current ASHP.