Thermodynamic performance of fuel cell-absorption refrigeration coupling system based on novel low-temperature working pairs

Thermal management of low-temperature proton exchange membrane fuel cells (LT-PEMFCs) remains a major challenge in hydrogen energy applications. A coupled system of LT-PEMFC combing with absorption heat pump using a novel hydrofluoroolefin (HFO)-based working pair was proposed in this study to recover the low-temperature waste heat of the hydrogen stack below 353.15 K. Based on the measured thermophysical properties, the thermodynamic performance of the coupled system was evaluated under various operating conditions. Results show that HFO-based working pairs (R1233zd(Z)/TEGDME and R1336mzz(Z)/TEGDME) exhibit lower driven temperatures, enabling the utilization of waste heat below 348.15 K without risks of crystallization or corrosion. Notably, R1233zd(Z)/TEGDME exhibits superior waste heat recovery performance. The cooling capacity of R1233zd(Z)/TEGDME is enhanced by 10 %, the coefficient of performance of the AHP system is improved by 12 %, and the exergy efficiency is also correspondingly increased in comparison with R1336mzz(Z)/TEGDME. The coupled system using R1233zd(Z)/TEGDME is able to effectively recover low-grade heat (348.15–368.15 K) for refrigeration at temperatures ranging from 268.84 K to 289.86 K. Under typical operating conditions, the coupled system achieves a comprehensive coefficient of performance of 0.7, which is about 55 % larger over the efficiency of LT-PEMFC. These organic working pairs provide an innovative solution for fuel cell thermal management by utilizing the low-grade waste heat.