Computational Study of Helical Coil Heat Exchangers for Water Systems

This paper, numerically examines the thermal behaviour of helical coil heat exchanger designed for water heating, aimed at using finite element simulation package, COMSOL Multiphysics. It has a helical coil which is positioned in a cylindrical water tank. A hot thermal fluid (HTF) is circulated through this coil that is used to impart its heat to stationary water through natural convection. The simulation supposes that the HTF has a constant temperature 350.15 K and velocity of 0.02 m /s flowing into the coil. The use of recognized empirical relationships allows evaluating the thermal and flow performance of the heat exchanger and leads to the method of identifying essential thermofluidic design parameters: Reynolds number, Nusselt number, Prandtl number, and the convective heat transfer coefficient. The hydraulic diameter is used to calculate the flow rate of mass flow and the rate of effective heat transfer based on the area of the coil cross-sectional area. These are some of the key parameters used to measure the thermal efficiency of the system and they are useful towards optimization of design of a compact and a high- performance heat exchanger that will serve domestic and industrial uses in water heating.