Development of a Stand-Alone Thermoelectric Power Generator Using Heat of Refrigerant Leaving the Condenser and Self-Cooled by Condensate of a Split-Type Air Conditioning

Today waste heat recovery of air conditioning is receiving considerable attention worldwide. This paper reports investigation on the development of a stand-alone thermoelectric power generator (STEG) using heat of refrigerant leaving the condenser and self-cooled by condensate of a split-type air conditioning. The STEG is composed of a small hollowed aluminum block integrated in the hot refrigerant line leaving the condenser to collect and transfer heat to the hot side of two thermoelectric (TE) modules 40 x 40 mm installed on the right and left. To cool the TE modules, water condensate circulates by gravity inside two aluminum alloy blocks. Tests were conducted using 2-tons split-type air conditioner installed in a 64 m3 room of a residential house in Bangkok. Electrical current generated by the two TE modules was recorded separately and connected in series three times for each case. Experimental results showed that STEG can produce electrical current continuously and varied depending on the operation on the compressor. The more important the cooling, the higher is the voltage produced. The maximum recorded voltage is about 200-250 mV by each TE module and doubled with the TE modules connected in series. The average water condensate flowrate was 11.56 g/min. The average coefficient of performance (COP) and the average Energy Efficiency Ratio (EER) of the air conditioning with STEG were 1.87-1.88 and 6.38-6.42 respectively, 3% higher than those of the conventional system.