Performance analysis of Isopropanol–Acetone–Hydrogen chemical heat pump

The performance of an Isopropanol–Acetone–Hydrogen (IAH) chemical heat pump system is investigated in terms of enthalpy efficiency (COP) and exergy efficiency, in which the exothermic and endothermic reactions take place in the gas phase. The increase of reflux ratio, temperature of endothermic reaction and temperature of exothermic reaction reduces the performance of the heat pump when the other operating parameters remain unchanged. However, the performance of the IAH chemical heat pump improves with the increase of the ratio of molar quantity of hydrogen to that of acetone in the entry of exothermic reactor and the number of heat transfer units of regenerator. Generally, a better performance of the chemical heat pump corresponds to a larger number of trays in the distillation column. The performance of the system can be improved significantly after multi-parameter optimization design. The coefficient of performance (COP) pays more attention to the heat released from the exothermic reactor, while the exergy efficiency takes into consideration of both heat released from the exothermic reactor and temperature of exothermic reaction.

► The increase of temperature of endothermic reaction reduces performance of heat pump.
► The better the performance is, the larger the number of trays.
► COP focuses on the quantity of recovered heat.
► Exergy efficiency focuses on the quantity and quality of recovered heat.