Performance assessment of low-GWP R134a alternatives in a vapor compression refrigeration system with thermoelectric subcooling

The growing need for sustainable refrigeration has accelerated the search for low-global warming potential alternatives to R134a for energy-efficient refrigeration systems. This study experimentally analyzes the integration of a thermoelectric cooling (TEC) module as a subcooling unit in a conventional vapor compression refrigeration (VCR) system for several low-GWP refrigerants: R152a, R513A, R290, R1234yf, and R600a. The experimental setup consisted of a nominal cooling capacity of 0.4 kW. Tests were conducted under the same conditions with an evaporating temperature of 0 °C, a condensing temperature of 45 °C, and an ambient temperature of 30 °C, while varying the thermoelectric cooling supply voltage from 1 to 10 V and the water mass flow rate from 1 to 3 L/min. R152a achieved the highest performance increase, with the coefficient of performance increasing by 12.3 % (from 3.07 to 3.45) and cooling capacity improving by 14.8 % at optimal operation. R513A demonstrated the most significant increase in cooling capacity, at 23.5 %, along with a 5.8 % improvement in the coefficient of performance. R290 improved the coefficient of performance by 13.4 % (from 2.87 to 3.25), while R600a showed moderate benefits. Subcooling up to 13.2 °C was achieved at a water flow rate of 3 L/min. The best performance was observed at 4–5 V, whereas higher voltages led to excessive power consumption. R152a and R513A emerged as the most promising replacements, offering balanced efficiency and performance benefits. This work presents new experimental results and practical metrics for next-generation refrigeration systems, addressing global warming prevention and energy efficiency targets.