Thermodynamic and Economic Analysis of a Phosphoric Acid Fuel Cell Combined Heating Cooling and Power System

This study proposes an innovative hybrid system that integrates a phosphoric acid fuel cell (PAFC) with an absorption refrigeration system (ARS) to enhance overall exergy efficiency. Waste heat from the PAFC is used in ARS generation. An evaluation is made of the energy efficiency, economic aspects, and the influence of the operating pressures of the two working fluid pairs, LiBr/H2O and R134a/DMF. In the combined PAFC-ARS, the absorption refrigeration unit incurs the highest exergy loss: 157 kW (R134a/DMF) and 146 kW (LiBr/H2O). The second-largest loss is experienced by the pure electrical generation PAFC unit at 117 kW. From an economic perspective, PAFC-ARS (LiBr/H2O) systems incur costs of USD 2.4/t for both hot water and cooling water, and USD 0.13 kW/h for electricity, with an 8 year payback period. In comparison, the R134a/DMF system entails costs of USD 2.1/t for hot water and cooling water and USD 0.16 kW/h for electricity. The PAFC exhibits a net output power of 434 kW, considering both energy and exergy perspectives. The corresponding maximum net electric energy efficiency (eta I) of the PAFC is 52%, while the overall exergy efficiency of the cooling model (eta II,dc) of the PAFC-ARS peaks at 56%, and the overall exergy efficiency of the heating model (eta II,dh) reaches its maximum at 61%. In conclusion, the PAFC-ARS (LiBr/H2O) demonstrates superior economic viability.