Effects of heat exchange condition on hot air production by a chemical heat pump dryer using CaO/H2O/Ca(OH)2 reaction

Results of an exploratory experimental study of a chemical heat pump (CHP) assisted convective dryer are presented. The CaO/H2O/Ca(OH)2 gas–solid reversible hydration/dehydration reaction is used to store and recover heat from the dryer exhaust air to enhance the thermal efficiency of the dryer. The CHP unit can be operated to increase the temperature level and also to dehumidify the air, which is a particularly attractive feature for drying. Results are presented for a single cylindrical reactor to study the effects of the heat exchange conditions on hot air production. The results show that the hot air production is improved by enlarging the heat exchanger, increasing the heat transfer rates by use of stainless mesh and increasing the air flow rate.