Development and investigation of a heat pump driven sorption storage heater for space heating applications

Present study investigates a heat pump driven sorption storage heater with the aim of demonstrating an energy efficient space heating method for buildings. In the developed process, useful heat could be extracted both in discharging process directly and charging process through a heat exchanger. Proposed system could utilize excess energy generated by photovoltaic panels and off-peak electricity tariffs to charge the sorption material to store heat for later use. The novel heat recovery process employed in the system enables to obtain high heat storage efficiency through condensation of desorbed moisture in heat storage charging cycle. In the developed prototype, composite Vermiculite-CaCl2 matrix was selected to be used as sorption material due to its good hygroscopic-hygrothermal properties and its low cost. Overall performance of the developed prototype sorption storage heater was numerically and experimentally investigated and results found in good agreement. According to study results, system could provide ≈6.8 kWh thermal energy output with the use of Vs= 0.04 m3 in 1200 minutes discharging time, corresponding to energy density (Ed) of 170 kWh/m3. The required charging duration, to desorb the moisture was experimentally determined as 360 minutes. Based on the total energy input– output in charging and discharging processes, COPS was calculated as 2.39.