Simulation of heat pipe-assisted latent heat thermal energy storage with simultaneous charging and discharging

Abstract

Melting and solidification of a phase change material (PCM) held within a vertical cylindrical enclosure that is integrated with a heat pipe (HP) is simulated as a single module. The HP is heated from the bottom to melt (charge) the PCM that is positioned in the middle of the HP length, and is cooled from the top to solidify (discharge) the PCM. Three modes of operation are considered in this study (i) charging-only, (ii) simultaneous charging and discharging, and (iii) discharging-only. All modes of operation are handled with a single HP within a PCM (single HP-PCM) of which the top and bottom sections are inactivated during charging-only and discharging-only modes, respectively. A parametric study of the influence of the PCM enclosure height and input/output heat transfer rates shows that, for the same mass of PCM, a longer enclosure exhibits a lower HP bottom average wall temperature and relatively more PCM melting during simultaneous charging and discharging. Increasing either the input, output, or both heat transfer rates has a significant effect on the temperature of the HP bottom and top sections, but only a minor impact on the temperature of the HP middle section.

Heat pipe heat exchangers and heat sinks: Opportunities, challenges, applications, analysis, and state of the art

“…The authors concluded that PCM-HPHX systems with a smaller HP-HP spacing have smaller temperature drops and higher exergy efficiencies. An alternative PCM-HPHX design for integration with Dish-Stirling systems was studied by Sharifi et al [71] in which a single HP was used for both charging and discharging of the PCM. In a related study, Cui et al [72] considered a HP receiver in which a HP directly receives solar irradiation and transfers it to a PCM and external fluid flow.…”

Development of an Integrated Thermal Energy Storage and Free-Piston Stirling Generator for a Concentrating Solar Power System

“…Shabgard et al [40] investigated the use of a heat pipe PCM TES system for use in a dish-Stirling system where the PCM acts as a thermal buffer to alleviate transients in solar insolation. Sharifi et al [41] examined a system that had a single heat pipe that was used for both charging and discharging of the PCM for a dish-Stirling receiver. In a system considered by Cui et al [42], a heat pipe is directly irradiated and transfers the energy to the PCM and heater head.…”

An experimentally verified numerical model of finned heat pipes in crossflow

“…Numerical modeling has been used to analyze heat transfer processes both (i) within HPs [22][23][24][25][26][27][28][29][30][31][32] and (ii) external to HPs such as those equipped with exterior fin arrays [19][20][21][22]. Both approaches have employed simplifying assumptions.…”