tested and analyzed a direct
expansion solar-assisted heat pump water heater with rated input
power 750 W. The performance of the first system with rated
input power 750 W was shown through experimental research in
spring and thermodynamic analysis and some suggestions for the
system design optimization are proposed. Then, a small-type
system with rated input power 400 W with new type collector/
evaporator was built, tested, analyzed and then compared with the
first system. Under similar running cost expected, the smaller
system with lower capital cost and smaller collector/evaporator
area has the advantage so as to integrate it with building’s roof.