Experimental and numerical study on performance of hybrid refrigeration system that combines vapor compression and thermoelectric systems

As high-quality food preservation has become an important aspect of daily life, a need has developed for domestic household refrigerators with a wide refrigeration temperature range. The temperature range of domestic household refrigerators is generally above −20 °C. In this study, a hybrid refrigeration system that combined vapor compression refrigeration (VCR) and a thermoelectric refrigerator (TER) is investigated for the freezer compartment of a domestic refrigerator with a volume of 0.018 m³. Although an additional 99.5 W of electrical power is consumed, a lower temperature of −38.1 °C is experimentally achieved in the deep freezer compartment of a compact VCR–TER system, with no noise or mechanical parts. In contrast, a temperature of only −8.8 °C is obtained in a typical VCR system. A three-dimensional numerical model is applied to study the performance of the finned heat sink of the TER using FLUENT. The effects of the fin height and fin pitch on the thermal resistance and pressure drop are investigated. The results show that the thermal resistance decreases with an increase in the fin height and increases with an increase in the fin pitch. An optimized finned heat sink with a fin height of 50 mm is obtained, which has a thermal resistance of 0.05 °C/W. It has a higher cooling capacity of 53.6 W than the heat sink with the original fin height of 30 mm. The VCR–TER system has potential application to low-temperature domestic refrigeration systems with a small size and small cooling capacity.