Energy-saving potential of an R600a household refrigerator through mixing with R290 and adjusting compressor revolution speed

This study experimentally investigated the effects of R600a/R290 blends and compressor speed on the performance of a household refrigerator-freezer (HRF) originally designed for R600a. An experimental apparatus was constructed to simulate a reference HRF, and the performance of the vapor-compression refrigeration system (VCRS) was evaluated using R600a/R290 blends (100/0, 95/5, and 90/10 % by mass) across a range of compressor speed. For comparison, benchmark performance with pure R600a was measured at medium (45 Hz) and high (60 Hz) compressor speeds. Results showed that the 95/5 % blend achieved comparable performance to the pure R600a system at significantly reduced compressor speeds. Specifically, operation at 36–37 Hz matched the performance of the 100/0 % case at 45 Hz, while operation at 47–48 Hz matched the 60 Hz benchmark. The 90/10 % blend achieved equivalent performance to the 60 Hz R600a case at just 38–39 Hz. These reductions in compressor speed led to lower power consumption and notable improvements in coefficient of performance (COP). Compared to the 45 Hz reference case (pure R600a), the 95/5 % blend improved COP by 8–14 %. Against the 60 Hz benchmark case, COP increased by 18–21 % for the 95/5 % blend and by 23–33 % for the 90/10 % blend. Even under elevated condenser outlet temperatures ( ≥ 40 °C), the 95/5 % blend resulted in a COP increase of 8.4–10.7 %, demonstrating its potential to enhance the energy efficiency of household refrigerators, particularly in hot climates.