Development of a hybrid refrigerator combining thermoelectric and vapor compression technologies

A domestic refrigerator with three compartments has been developed: refrigerator compartment, at 4 °C (vapor compression cooling system); freezer compartment, at −22 °C (vapor compression cooling system); and a new super-conservation compartment, at 0 °C (thermoelectric cooling system). The thermoelectric system designed for the super-conservation compartment eliminates the oscillation of its temperature due to the start and stop compressor cycles, obtaining a constant temperature and thus, a better preservation of the food. For the design and optimization of this application, a computational model, based in the numerical method of finite differences, has been developed. This model allows to simulate the complete hybrid refrigerator (vapor compression–thermoelectricity). The accuracy of the model has been experimentally checked, with a maximum error of 1.2 °C for temperature values, and 8% for electric power consumption. By simulations with the computational model, the design of the refrigerator has been optimized, obtaining a final prototype highly competitive, by the features on food preservation and power consumption: 1.15 kW h per day (48.1 W) for an ambient temperature of 25 °C. According to European rules, this power consumption value means that this new refrigerator could be included on energy efficiency class B.