Tri-generation design and analysis of methanol-reforming high-temperature fuel cell based on double-effect absorption cooling power cycle

Abstract

The methanol-reforming based high-temperature proton exchange membrane fuel cells is promising in both stationary and mobile applications, due to the trade-off between the efficiency and durability. However, challenges arise in the system integration due to the coupling of various-grade heat flows. Additionally, the exiting waste heat recovery systems face thermal-electric coupling issues, leading to limited flexibility in the energy supply. To this end, a thermally coupled tri-generation system based on methanol-reforming high-temperature proton exchange membrane fuel cell and double-effect absorption cooling power cycle is proposed. The cooling oil cycle absorbs heat from the fuel cell stack and burner, supplying heat for the preheaters, methanol reformer and double-effect absorption cooling power cycle. The cooling and power outputs of the double-effect absorption cooling power cycle are flexibly adjusted by varying the vapor split ratio. The mathematical models are developed and validated, based on which the exergy, exergoeconomic, economic and environmental performances are investigated. Under the design conditions, the tri-generation system yields net power, cooling, and hot water of 102.8 kW, 64.75 kW, and 43.83 kW, respectively, with exergy efficiency of 39.0% and unit exergoeconomic cost of product exergy of 65.09 $/GJ. The economic and environmental analyses indicate that, compared to the conventional system, a 54.2% reduction in carbon dioxide emissions is achieved, and the payback periods stand at 4.0, 5.6 and 9.0 years for the methanol prices of 0.40, 0.45 and 0.50 $/kg, respectively.