Experimental Evaluation of Hot-Water Thermal Storage with Auxiliary PV Heating in a Solar-Driven Absorption Cooling System

Abstract

Solar-powered Absorption Cooling system is one of the promising options for sustainable refrigeration; however, their performance suffers due to thermal lag from intermittency of solar energy and thermal storage medium. In this paper, a novel approach to thermal regulation that integrates PTC collector, hot water thermal energy storage with an auxiliary PV heating loop, which operates under extreme environmental conditions of up to 38.9 °C air temperature and irradiance up to 940 W/m², is investigated through experimental research. The main innovation of this technology is that the auxiliary heating process is implemented directly from PV source. As per experimental observations, water running through the system at the rate of 1.2 L/min was able to achieve the maximum useful heat gain (Qu,water) of 2800 W and efficiency ηwater of 48.59% at 12:00 hours. On the other hand, thermal oil running through the system at the flow rate of 2.7 L/min showed significant thermal lag, which reached the point of maximum useful heat gain (Qu,oil) of 2336 W and efficiency ηoil of 41.50% after an hour of lag, i.e., 13:00 hours. However, with the help of the active PV heating unit, constant increase in temperature was experienced for the hot-water storage tank, ranging from 3 to 8°C. This way, a steady thermal effect helped in increasing the temperature inside the storage tank to 87°C (versus 79°C in PTC-only system) at 14:00 hours, while increasing generator temperature (Tg) to 108°C at 13:30 hours. Thus, the complete system reached COP of 0.79. As seen in the present study, incorporation of active PV heating along with hot-water thermal storage could prove to be a novel passive-active strategy against storage inertia.