30 May 2005


An innovative multi-function solar heat pump system is investigated in this study. The most
important feature of this system is that it can serve space heating/cooling, water heating and drying
simultaneously or independently. A system was designed and fabricated and a series of experiments were
conducted to evaluate the performance under the meteorological condition of Singapore. Comparison of
the multi-function system for different running modes and speeds of the compressor was carried out. The
presence of evaporator-collector enabled the system to work round the clock, even in the absence of
sunlight. Refrigerant R134a was selected as the working fluid due to its favourable thermodynamic
properties. Experimental results show coefficient of performance (COP) of 4.58. Experimental
results obtained under part load show that the air-conditioning greatly enhanced the heating
effect. The efficiency of the unglazed evaporator-collector, which was found to be close to 1 with
a maximum of 1.7, is much higher than the conventional collector. Results indicate that this multifunction
system can meet domestic and industrial requirements and save considerable amount of energy
when compared with the conventional air-conditioner, water heater and dryer. The system is considered
environment friendly and show good potential for application in tropical areas, where solar
energy is abundantly available.