CFD Analysis of Double Pipe Helical Coil Heat Exchanger With Micro-fin Inserts

Abstract

The enhancement of heat transfer in helical coil heat exchanger has been done by many researchers. One of the key factors of designing compact heat exchangers is enhancement of heat transfer. This enhancing is done by many ways like adding extra surface area. In this process, without using external power, we can increase the heat transfer rate. Till now the research had been done on straight tube heat exchanger and a small amount of work done on helical coil heat exchanger, but no research has been done on the helical pipe with micro fins. This study is conducted to find out the advantage of adding extra surface to the helical coil heat exchanger surface by using micro fins. This helical coil heat exchanger has many applications in aerospace, nuclear reactors, automobile industries, food industries, power plants etc. because of some advantages over the straight tube. In this study of the double pipe helical tube (tube-in-tube) heat exchanger with micro fins analysis is done for different boundary conditions and compared with the helical coil without fins. This study optimises the better condition for heat transfer with different circulation ratio. The turbulent flow model with counter flow heat exchanger is considered for analysis purpose. The geometry part made in SOLIDWORKS2012 & analysis has been done in ANSYS FLUENT 15.0 software. The effect of curvature ratio on heat transfer and friction factor; overall heat transfer rate has been studied for insulated wall, constant wall temperature boundary conditions with different flow rates in each case and studied the variation with the helical pipe heat exchanger without fins. It is observed that by adding fins to the helical coil inside of the pipe, the heat transfer is increased by 1.4 to 2 times of the heat exchanges without fins (for two turns of the coil), and friction factor is also increased, compared to heat exchanger without fins.