G. Kumaresan

Investigation on Phase Change Behavior of Paraffin Phase Change Material in a Spherical Capsule for Solar Thermal Storage Units

ABSTRACT In this work, the melting and solidification behaviour of paraffin phase change material encapsulated in a stainless steel spherical container has been studied experimentally. A computational fluid dynamics analysis has also been performed for the encapsulated phase change material (PCM) during phase change process. In the melting process, the hot air, used as the heat transfer fluid enters the test section and flows over the spherical capsule resulting in the melting of phase change material. In the solidification process, the ambient air flows over the capsule and received heat from phase change material resulting in the solidification of phase change material. In the computational fluid dynamics, the constant wall boundary condition is employed for both melting (75°C) and solidification (36°C) processes since the internal conductive resistance offered by the PCM is much higher compared to the outer surface convective resistance. The time required for complete solidification and melting of the phase change material obtained from the computational fluid dynamics analysis are validated with the experimental results and a reasonable agreement is achieved. The reason for the deviation between the results are analyzed and reported.

Numerical Analysis of Baffle Cut on Shell Side Heat Exchanger Performance with Inclined Baffles

ABSTRACT In this work, an attempt has been made to decrease the pressure drop and to increase the heat transfer rate in a shell and tube heat exchanger (STHX) by tilting the baffle angle and by varying the baffle cut. The process of solving the simulation includes modeling, meshing, and analyzing the geometry of the STHX by using Pro-E, hypermesh, and computational fluid dynamics package of ANSYS Fluent, respectively. The objective of this study is to find a suitable baffle inclination and baffle cut for the efficient performance of the STHX. The baffle inclinations of 25°, 30°, 35°, and 40° were considered for three different baffle cuts of 25%, 30%, and 35% of shell inside diameter and the results were compared with segmental baffle of inclination angle 0°. The shell side flow with different inclination angles and baffle cuts results in a significant variation in heat transfer rate and pressure drop in the STHX. The results provide a clear idea that the heat transfer rate is maximum in inclined baffle heat exchanger compared to that of segmental baffle heat exchanger. Further it is found that the STHX with the configuration of 35º baffle inclination angle and baffle cut of 30% of shell inside diameter provides higher heat transfer rate with minimum pressure drop compared to all other configurations.