Experimental investigation of open sorption pipe heat storage under North Cyprus climate conditions

Thermal energy storage systems have gained much attention in recent years as they are now seen as one of the most promising solutions to increase utilisation of solar energy and reduce greenhouse gas emissions. In the last decade, thermochemical versions of these systems have been widely researched for ‘seasonal’ storage of solar energy as they have the potential to store heat at ambient temperatures for extended periods of time without any degradation or heat loss. In this study an experimental analysis is carried out to investigate the applicability of thermochemical heat storage for space heating facilities under Northern Cyprus climate conditions. For this purpose a prototype sorption pipe was developed and the composite SIM-3a (Vermiculite – CaCl2) was used as the absorption media. The discharging part of testing was conducted in a 12.4 m² test room whilst the charging process was conducted in an open environment with an integrated concentrating solar panel attached to the sorption pipe to dehydrate the material. According to the test result, a heat storage density (Ed) of 219 kWh/m³ was achieved with a moisture sorption rate of 0.22 kg/h. The average thermal power output (Qout) was found as 0.303W for a 9.38 h discharging period. During that period, the total thermal energy (Et) provided by the heat storage was determined as 87% of the total heat load (El) of the test room. The charging period lasted 6 h with a desorption rate of 0.22 kg/h achieved using the solar energy. This corresponds to a drying ratio of 60%. In the discharging process encouraging results were achieved however for the charging process further improvement will be required to utilize the solar energy more effectively to fully dehydrate the absorbent.