Study on Thermal Performance of Single-Tank Thermal Energy Storage System with Thermocline in Solar Thermal Utilization

Abstract

For the intermittence and instability of solar energy, energy storage can be a good solution in many civil and industrial thermal scenarios. With the advantages of low cost, simple structure, and high efficiency, a single-tank thermal energy storage system is a competitive way of thermal energy storage (TES). In this study, a two-dimensional flow and heat transfer model of a cylindrical storage tank with water as heat transfer fluid (HTF) is developed, in which the effects of time, flow velocity, and height-to-diameter ratio of the tank on the thermocline thickness have been highlighted. The results show that the thermocline thickness in the storage tank is increasing during the charging and discharging processes, and it increases with the increase of the inlet flow velocity and the height to diameter ratio. It is emphasized that in our cases when the time period of t is 14,400 s, the fluid inlet velocity of uin is 4.577 × 10−4 m/s, and the height-to-diameter ratio of H/D is 1.2, the performance evaluation index reaches the maximum 0.9575, and the efficiency of the system is the highest. It is expected that all of the findings herein can provide a fundamental understanding of the design and operation of the single-tank thermal energy storage system in water heating for civil and industrial applications.

Techno-Economic Analysis of Latent Heat Thermal Energy Storage Integrated Heat Pump for Indoor Heating

“…kg/m 3 864*/760 *calculated from the volume expansion Height-to-diameter ratio (H/D) is a crucial parameter in designing a thermal energy storage tank. The increase of H/D can improve the charging and discharging efficiency and reduce the occupied area, while it also results in increased weight and cost of the tank, and in increased heat loss [45][46][47]. Considering the charging/discharging time and required heat capacity, the H/D was set as 1.7 with inner diameter of 0.6 m. A 2D axis-symmetrical model was built to simulate the thermal processes of LHTES, shown in Figure 6.…”

Modular heat storage in waste heat recovery installations

“…In the literature, one can find various uses of thermal energy storage with phase change substance, which accumulate waste heat and heat from solar energy [22,23]. Phase change materials have a high heat capacity but only in a narrow temperature range, while water works better in a broader scope.…”