Numerical investigation on heat and fluid flow characteristics of helixchanger using nano materials (CuO and Al2O3) blended with working fluid

Abstract

The heat exchanger system is one of the important components for many of the non-conventional power-producing system. These heat exchanger systems may be used effectively as absorbing and storing heat from say solar ducts/panels, exchanging the heat for solar assisted refrigeration systems, etc. However, developing a compact and high effective heat exchanger system is a challenge. It has also been seen that the heat transfer will be more for the turbulent flows or flows where mixing dominates with higher heat transfer coefficient values. In this paper, we have developed a small concentric annulus heat exchanger having a helical flow passage. This compact heat exchanger is utilized to replace the electric heat source supplied to the Electrolux refrigerator. The helical flow is produced by providing a helical metal baffle between the two concentric annulus pipes. The working medium through the helixchanger is nanoparticle blended with water. CuO and Al2 O3 are the two popularly nanomaterials are mixed with water and their effectiveness is compared. The discrete phase model (DPM) based numerical simulation of the three-dimensional flow through helixchangers is presented here. The DPM exactly mimics the actual flow scenarios where nanoparticles are injected/blended along with the flowing fluid and expected to provide a realistic solution. The flow-through helixchanger is simulated for various Reynolds numbers and corresponding pressure drop, the average heat transfer coefficient is studied and presented here. Due to added nanomaterial in the working medium, the heat transfer is found to be increased by 25-30% as compared to without nanomaterial blend. Also, there are negligible pressure changes hence indicating the same pump power requirements for pumping. At the last, the results are validated with experimental values and their matching is found good.