Effect of the design variables on the energy performance and size parameters of a heat transformer based on the system acetone/H₂/2-propanol

A high-temperature chemical heat pump based on the system acetone/H₂/2-propanol for waste heat recovery was studied. Two reversible catalytic chemical reactions are involved in this system. The waste heat (at 333–353 K) is recovered by means of the endothermic liquid-phase dehydrogenation of 2-propanol, and is upgraded at high temperature (453–473 K) by the reverse reaction, the exothermic gaseous-phase hydrogenation of acetone. In this process, a fraction of the recovered waste heat is removed at low temperature (303 K), to carry out the separation by vapour rectification between acetone and 2-propanol.

A mathematical model was developed, that permits the study of the effect of the heat pump operating conditions on the energetic performance (COP), exergetic efficiency and size parameters. Also, this model allows the estimation the optimal range for the system control variables. Under these conditions, the energy and size parameters have been calculated on a basis of 0.32 MW upgraded heat.