Experiments of a Heat Pump Water Heating System Using Stored Solar Energy to Defrost

摘要

A new solar-assisted hot water heat pump system is proposed that uses stored solar energy to defrost the outdoor unit. The system is mainly featured by two water tanks, one of which can be used to collect part of the solar heat during daytime and is used in the defrosting processes during night. Experiments were conducted in lab conditions to test the performance of this novel design, in which the solar heating systems was represented by electrical heating. Results show that the new system had a system COP almost 82% higher than the traditional system where the reverse-cycle defrosting uses the water thank as the evaporator. The advantage of this system is that it can make use of the low grade solar heat, which is difficult to collect or use in normal solar water heating system. This system is particularly suitable for regions with cold and humid winters like the hot summer and colder winter zone in China.