Calcium oxide/steam chemical heat pump for upgrading waste heat in thermochemical hydrogen production

This paper presents a numerical study of a chemical heat pump (CHP) for upgrading waste heat from a cement plant for thermochemical hydrogen production. A calcium oxide/steam CHP is investigated as a potential system to upgrade waste heat from industrial processes for thermochemical hydrogen production. The heat produced by the CHP drives the decomposition of copper oxychloride (CuO·CuCl2) in a copper–chlorine (Cu–Cl) thermochemical cycle. A transient analysis of the temperature distribution in each sub process in the combined CHP/Cu–Cl cycle is presented in this study. The numerical results of hydration temperature distribution are compared with experimental results to validate the predictive model. A maximum hydrogen production of 12.28 mol/kg Ca(OH)2 can be achieved from the combined system analyzed in this study. The effect of heating load and oxygen decomposition supply temperature is reported for the hydration, dehydration, condenser and evaporator heat transfer processes.