Performance Improvement Techniques in Shell-and-Tube Type of LHS Unit

This study presents a thermal performance comparative study of three shell-and-tube latent heat storage (LHS) models. With the help of the optimization technique, 19 tubes are chosen with an internal and external diameter of 17 mm and 20 mm, respectively. In the first case, the LHS model is considered without fins. In the second case, the LHS model is also modeled without fins, but the phase changing materials (PCM) are mixed with 5% volume fraction of Cu nanoparticles. In the third case, every HTF tube is supported by four fins. In order to maintain the same volume of PCM in all the models, shell diameter of the first LHS model is 235 mm and for the second and third cases, the diameter is set to be 240 mm. Commercial sugar alcohol known as Erythritol (C4H10O4) is considered as PCM. ANSYS Fluent environment is employed for the numerical modeling and solution of the governing equations representing PCM. The performance study of LHS units is evaluated using parameters, such as transient temperature and liquid fraction. In order to account buoyancy impact of liquid PCM, Boussinesq approximation method is applied to the model. The inner walls of the HTF tubes are maintained at 138 °C as inlet temperature. The numerical estimations are validated against experimental results. LHS model in the third case, which is supported by fins, becomes fully charged after 80 min, whereas, LHS models in the first and second cases take 120 and 136 min, respectively, for complete melting.