Thermal performance of a novel thermoelectric refrigerator with a water to air heat exchanger and SiO2, TiO2 and Al2O3 nanofluids

Thermoelectric refrigeration is an eco-friendly and cost-effective cooling method, basically defined as the process of pumping thermal energy out of an insulated medium for reducing the temperature of the medium below that of the surrounding air. Thermoelectric refrigeration is based on a phenomenon called Peltier effect to pump the said heat from one layer to another. Thermoelectric coolers (TECs) are usually utilised for electronics cooling today, however, there are several attempts to expand their application areas like in space cooling. In this research, a novel TEC system was devised, fabricated and experimentally analysed for a potential alternative to conventional refrigerators in the built environment. The novel TEC unit consisted of a heat absorbing and heat dissipating part, which represented the evaporator and the condenser of the system, respectively. Optimum heat sinks were considered for the aforesaid parts, and additionally, a water to air heat exchanger was integrated to the heat dissipating section for the thermal regulation of the hot surface. The water to air heat exchanger was so effective that only 1°C temperature difference between the heat exchanger fins and the surrounding air was observed in all tests. The tests were carried out for a constant surrounding air temperature in the range of 20-21°C with pure water. Moreover, some further tests were conducted with SiO2, TiO2 and Al2O3 nanofluids at a certain mass fraction. The results revealed that the coefficient of performance (COP) of the novel TEC system was 0.23 for without load condition whereas it was 0.09 with load. The COP was enhanced by about 1.2, 3.7 and 9.6% via the nanofluid integration of SiO2, TiO2 and Al2O3, respectively for the case of without load.