Water adsorption characteristics of novel materials for heat transformation applications

Within this article we illustrate recent development of sorption materials for heat transformation applications. A broad overview on the possible performance of currently available and recently developed materials ranging from zeolites across aluminophosphates and silicoaluminophosphates to the novel class of metal organic framework materials is given. Materials are evaluated with respect to the use in thermal driven adsorptive heat pumping and cooling applications with water as refrigerant. Therefore a new fingerprinting method is used to evaluate samples under two typical cycle conditions with driving temperatures of 95 °C and 140 °C. A unique aspect is that results can be used for closed as well as for open adsorptive systems.
The highest water uptake for driving temperatures of 95 °C was found for an AlPO-18 with 0.253 g/g, which is more than six times higher than the reference silica gel in our comparison. For driving temperatures of 140 °C the highest water uptake was found for the metal organic framework Cu-BTC with 0.324 g/g.
Furthermore we give first results on the integral heat of adsorption in the cycle and results of hydrothermal treatment of most promising materials.