A recent state of art review on heat transfer enhanced characteristics and material selection of SCTHX

The shell and coil tube heat exchangers (SCTHX) are widely used to transfer heat energy from one medium to another effecting medium, such as refrigeration and air conditioning system, chemical reactor, solar heater and steam power plant. The helical tubes are one of the passive heat transfer enhancement technique in heat exchanger, which are adopted in industries due to higher rate of heat transfer and simplicity in manufacturing. It has been widely employed that heat transfer coefficient in helical coils are higher compare to straight pipe by several researchers. The reason is behind that the formation of secondary flow of nano fluid. It is leading by dean vortex which is imposed to primary flow. Furthermore research on segmental and helical baffle geometry can improve the heat transfer rate in helical coil tube heat exchanger. This study is concerned with the enhancement of convective heat transfer interaction between fluid and solid surface of helical coil. The detailed descriptions of material selection, nano fluid flow physics and heat transfer enhancement inside helical coil tube are very less in open literature. A state of art review indicates that further research work can be carried out by modifying the geometry of SCTHX and enhance factors of fluid property. The heat transfer can also be enhanced by polymer additives added in nano fluids, effect of super hydrophobic surfaces and fluid bubbles generation from roughened heating surface. Finally new ideas are presented in this paper to improve the heat transfer rate and material selection for low cost manufacturing with minimum size.