Dual-Evaporator, Variable Capacity Refrigerator, Coupled with Thermoelectric Freezer

DOE is promoting research in non-vapor-compression refrigeration technologies. One potentially revolutionary non-vapor-compression mechanism is to use thermoelectric (TE) technology that can use DC (direct current) electricity to pump heat from a low-temperature heat source to a high-temperature sink via the Peltier effect. Thermoelectric heat pumps are widely applied in the electronics cooling industry with COPs > 3.0 for 10K (18R) ΔT. Thermoelectric elements are compact, low-cost, and widely available in the market. Their recently proven ability for other heating uses such as thermoelectric clothes dryers and their confirmed technical feasibility for all space heating and cooling applications for residential/commercial buildings are very promising. Stand-alone thermoelectric cooling has already been used for portable refrigerators on the market. Since TE elements are compact and portable, there is a chance that we can cascade a TE cooler with the evaporator of a single-stage refrigerator system. The goal of this project is to use a compact TE heat pump to bridge the temperature difference between 0˚F (freezer temperature) to 25˚F (required evaporating temperature for FFC cooling). The TE modules will be used to cool the freezer at 0˚F and pump the heat to a phase change material (PCM) layer integrated with a refrigerant evaporator. A PCM layer will provide thermal insulation between the two chambers and balance the capacities between the VC and TE cycles. DC (direct current) driven TE will melt the PCM at varied fraction to adjust the compressor run time, eliminate cyclic loss, improve the food preservation quality, and provide grid-responsive energy storage.

Project Impact

This project aims to develop an innovative refrigerator that combines a thermoelectric cooler with a traditional compression system, achieving precise temperature control in individual compartments. It will develop a grid-interactive supervisory control system to maximize renewable energy utilization, achieve electricity savings of 15%, and reduce utility costs by 30%. This project will also investigate a new defrosting mechanism using the thermoelectric heat pump and conducting energy factor tests to verify energy performance. Finally, a field demonstration will be conducted to test a prototype refrigerator and gather real-world data.