Testing the lab-scale “Heat from Cold” prototype with the “LiCl/silica - methanol” working pair

Adsorptive transformation of heat is an energy and environment saving technology, which allows effective utilization of low temperature heat sources. Recently, a new adsorption cycle (the so-called “Heat from Cold” or HeCol) has been suggested for amplification of the ambient heat in cold regions up to higher temperature, suitable for heating. In this paper, at first we analyzed which adsorbent is needed for practical realization of the HeCol cycle. Then, the composite sorbent, based on LiCl and silica gel, was selected for the comprehensive study, and its sorption equilibrium with methanol was analyzed keeping in mind the requirements of the HeCol cycle. Finally, a first lab-scale HeCol prototype was tested with the LiCl/silica sorbent to evaluate the feasibility of the new cycle. The effects of the heat source temperature and the rate of heat transfer fluid on the prototype performance were studied. It was shown that at heat source temperature of 20-30 °C, the maximum temperature of the released heat reaches 34-53 °C, which is suitable for warm floor and hot water systems. The maximum specific heating power varies from 6.0 to 10.8 kW/kg and the sorbent heating capacity reaches 620 kJ/kg. The results obtained clearly demonstrate that the use of the LiCl/silica sorbent allows quite compact HeCol units to be designed.