Thermal storage performance of a horizontal eccentric distance spiral shell-tube heat storage tank

Considering the delayed thermal response rate exhibited by a horizontal spiral shell-tube heat storage tank during the heat storage process, we introduce an eccentric distance spiral shell-tube heat storage tank model to address the above-mentioned limitation and enhance overall performance. The numerical simulation is used to simulate the thermal loading behavior of the three-dimensional model structure with different eccentric distances throughout the melting process. The results demonstrate that an eccentric distance can effectively expedite the melting process of the PCM. When the eccentricity of the tank is raised from 0 mm to 20 mm, the amount of heat storage remains relatively constant throughout this range. However, the melting time experiences a notable reduction of 47.19 %. Additionally, the average heat storage rate significantly increases by 83.85 %. It is worth noting that further increasing the eccentricity to 30 mm doesn't lead to significant optimization in the melting process. Subsequently, the influence of inlet temperature and flow rate on the thermal storage performance is investigated using a tank with an eccentricity of 20 mm as a reference unit. The results show that when the inlet temperature is increased from 343 K to 358 K and the flow rate is increased from 0.034 kg/s to 0.136 kg/s, the heat storage capacity is increased by 11.02 % and 2.21 %, the melting time is shortened by 46.21 % and 25.44 %, and the average heat storage rate is increased by 106.41 % and 37.07 %, respectively. However, it is essential to note that at an inlet temperature of 363 K, the thermal storage performance of the tank experiences a notable decline. The results of this research provide useful guidelines for enhancing the thermal storage efficiency of the horizontal spiral shell-tube heat storage tank.