Multi-objective optimization of a combined cooling, heating and power system integrated with reformed methanol high-temperature proton exchange membrane fuel cell

Reformed methanol high-temperature proton exchange membrane fuel cell (RM HT-PEMFC) systems demonstrate potential for both mobile and stationary applications. However, optimizing key variables is challenging due to the complex coupling of heat flows across various temperature levels. This study develops a combined cooling, heating and power system by integrating the RM HT-PEMFC with a double-effect LiBr-H₂O absorption refrigeration cycle. The proposed system is optimized using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), targeting system exergy efficiency, specific CO₂ emissions, and exergy cost per unit product. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is employed to determine the optimal values of objectives: an exergy efficiency of 43.12%, specific CO₂ emissions of 0.510 kg/kWh, and exergy cost per unit product of 167.59 USD/GJ, representing improvements of 20.73%, reduction of 17.10%, and 1.07% compared to baseline. The optimized ranges for key parameters are identified as follows: stack temperature (173.94–179.91°C), steam to carbon ratio (1.78–1.80), current density (0.20–0.40 A/cm²), and cathode stoichiometry (2.29–2.52).