Reaction control of CaSO4 during hydration/dehydration repetition for chemical heat pump system

As a result, the major cause of the reaction degradation within the CHP system was considered to be the irreversible transformation of III-CaSO4 into II-CaSO4 of the CHP materials occurred by the repeated reaction in high pressure depending on the temperature and pressurized time. The transformation occur in the dehydration step of CaSO4·1/2H2O particles. The appropriate temperature together with water vapor pressure in the repeated dehydration more than 288 times were found to be 423 K at 30 kPa, 413 K at 151 kPa, and 403 K at 453 kPa. From these results, the CHP system is able to increase the repeated reaction times by the appropriate pressure control for increasing the durability of the CHP materials.