Experimental study of a thermochemical heat transformer using deposit of CaCl2

A challenge in thermochemical heat transformers (THT) is to increase the specific heat power without compromising the temperature lift and cycle stability of the system. The objective of this study is to evaluate the potential of the salt hydrate calcium chloride (CaCl2) in a 1-salt 1-stage and 2-salts 1-stage experimental THT for waste heat upgrade. The first 3 equilibrium reactions have been identified indicating large temperature lifts possible in the target operating conditions (waste heat under 100 °C upgraded till 150 °C and higher). In the 1salt 1-stage configuration, the CaCl 2 packed bed produced large temperature lifts between 38.2 °C and 70.4 °C from a waste heat ranging from 82.7 °C to 98.7 °C with generally short reaction times. In the 2-salts 1-stage configuration, the same upgrade conditions lead to longer reaction times of the packed bed. A CaCl2-based deposit with PVA (polyvinyl alcohol) as a binder could also achieve identical temperature lift but in a much shorter time, which is promising for achieving a higher specific power.