Theoretical assessment of thermoelectric subcooling integration into a propane vertical freezing cabinet to minimize its energy consumption

The Kigali amendment boosts the use of hydrocarbons for vapor compression refrigeration cycles due to their negligible effect to the environment. However, vapor compression refrigeration systems do not only negatively affect the environment due to their use of refrigerants, but also due to their energy consumption. Many technologies have been studied to reduce the energy consumption of propane systems, where including thermoelectric subcooling into propane vapor compression systems has been barely studied. This manuscript studies for the first time the inclusion of a thermoelectric subcooler without auxiliary consumption into a propane vertical freezing cabinet to extend its use. The thermoelectric system is placed after the condenser and it is able to subcool the propane thanks to the forced airflow of the condenser, a novel arrangement that cannot be found in the literature. Additionally, the number of thermoelectric modules and their voltage supply have been optimized. The inclusion of a robust and simple thermoelectric subcooler made out of 12 thermoelectric modules arranged in 6 blocks and supplied with 1.5 V, procures a 5.96 % decrease of the daily energy consumption of the freezing vertical cabinet. Additionally, for this arrangement, the cooling capacity is increased an 8.50 % and the COP a 6.13 % by the 15.48 K degree of efficient subcooling achieved. The minimum payback period obtained equals 4.6 years for a thermoelectric subcooler made of two blocks and supplied with 2.5 V.