Numerical and Experimental Investigation of Finned Tube in Thermal Energy Storage Unit Filled with Phase Change Material

Abstract

In modern world, use of phase change materials (PCMs) in a thermal energy storage system is an efficient way to store energy. There are many applications of thermal energy storage system in which PCMs is used, viz., heat pumps, solar systems, spacecraft thermal applications etc. The purpose of this dissertation work is to identify effect of geometrical changes on the melting process of PCM. Computational fluid dynamics (CFD) is used to analyze phase change process. Thermal energy storage tank consists of a vertical tube in tube geometry where outer tube consists of phase change material and inner pipe carrying hot fluid. Paraffin is used as latent heat storage material. Further, the study describes the effect of inlet temperature of heat transfer fluid on the phase change process. Two types of geometries used, viz., cylindrically and conically shaped made up of copper material. The number of fins used is 30 with thickness of 1 mm. The distance between two fins is 14 mm. Result shows that charging time is 2.56% less required for conical shaped storage system rather cylindrical shaped system. The results have been computed using CFD and actual experimentation considering the parameters viz. flow rate and inlet temperature of heat transfer fluid. The results of the numerical analysis and the experimental readings show the good agreement with each other. It is observed that as the mass flow rate increases, the effectiveness of the PCM based heat exchangers decreases.