Parametric analysis and optimization of A novel indirect solar energy storage tank

In solar heating systems, the hot water storage tank (HWST) plays a critical role in addressing the problem of intermittent solar radiation and mismatched thermal loads. However, conventional HWSTs suffer from severe mixing of hot and cold water, preventing the effective supply of high-quality hot water and limiting the widespread deployment of low-carbon heating systems. To enhance thermal storage performance, a novel indirect solar energy storage tank (NISET) is proposed for solar heating systems with innovative fast-responsive ability and advanced thermal storage performance. By establishing a mathematical model for the indirect unsteady thermal storage process, the three-dimensional numerical simulation is experimentally validated and employed to study the thermal storage characteristics and optimize the performances of NISET. The results show that a bottom heat exchange chamber combined with a standpipe structure significantly improves the temperature stratification effect and thermal storage capacity of NISET. The effects of key parameters of NISET on thermal storage characteristics and performances are further investigated. Eventually, the optimum performance of NISET is achieved at 1300 mm standpipe height and 100 mm standpipe diameter with an internal mass flow rate of 0.25 kg/s, of which the final storage exergy is increased by 1604.16 % when compared to the original structure.