Simulation and validation of PCM melting in concentric double pipe heat exchanger

Latent heat storage (LHS) has been widely used for energy storage. Compare to sensible heat storage, LHS has several benefits because of its high energy density, small unit sized and operating at low temperature. This paper is aimed to investigate the melting characteristic of phase change material (PCM) implemented in concentric double pipe heat exchanger. The investigation is carried out by both simulation as well as validation. The simulation is conducted using ANSYS FLUENT with double pipe shape of heat storage. The geometrical shape of the storage is double pipe heat exchanger, the PCM is stored in the inner tube meanwhile hot water is circulated in the outer tube. The dimension of the inner tube are 5 cm of diameter and 50 cm length. The diameter of outer tube is 10 cm and 60 cm length. The hot liquid is circulated from the inlet port and withdrawing from the outer port. The inlet and outlet ports are located away at the distance of 5 cm from the edge of the outer tube. The inlet and outlet ports are constructed at the bottom and upper part of the outer tube. The simulation is carried out at temperature 60°C of the hot liquid and flow rate at 4 liters per minute. The validation is also conducted at the same configuration with that on the simulation. The tweaked parameters are number of mesh and mushy-zone value. Results revealed that validation is numerically accepted at deviation less than 5% for melting time deviation. The validation is obtained at number of mesh is 144,000 and mushy-zone value is 1.4 × 10⁷. On the evaluation of temperature distribution similarity, all of coefficient correlation are obtained greater than 0.8 between simulation and experiment. Being a valid simulation model, it is enabled to be enhanced for predicting melting of phase change materials on the heat energy storage system.