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This paper gives an overview of several published current studies concerning heat transfer enhancement on the double pipe heat exchanger. Since double pipe heat exchanger has drawn much consideration due to simplicity and wide-range utility. The flow manipulation technique to enhance heat transfer in a double pipe heat exchanger has been frequently cited. Also, various research addressing working fluid on a double pipe heat exchanger has been discussed in detail. Another technique is known as surface modification that has an infrequent investigation comparing the other techniques. Correlation of Nusselt number and pressure drop coefficient shown in this overview. Future research opportunities are mentioned. [ABSTRACT FROM AUTHOR]

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 60oC 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 1.4x107. 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. [ABSTRACT FROM AUTHOR]