Computational Fluid Dynamic Simulation: Maximise The Percentage Of Air Distribution Inside Quasi-Flow Heat Exchanger

Abstract

Parallel plate quasi-flow air-to-air heat exchanger has been implemented in Heat Recovery Ventilation (HRV) system to enhance the operating efficiency even in small temperature difference. In the HRV system, heat energy from the exhaust air is recovered to pre-treat the fresh air coming into the air-conditioning systems. Therefore, the HRV system can reduce the power consumption of Heating, Ventilation and Air Conditioning (HVAC) systems by enhancing the performance of the HRV system. Air velocity distribution over the plate of heat exchanger has a strong effect on the HRV system performance. The higher the percentage of area covered with air across the plate, the higher the heat transfer rate between two airstreams.

Inside the plate of the heat exchanger, duct inlet entrance causes air distribution to be non-uniform. Factor affecting air velocity distribution over the plate is investigated to reduce air velocity maldistribution. A simulation using ANSYS is conducted to investigate the effect of different louvres arrangements on the air velocity distribution across the plate of the heat exchanger. Results show that, with a smaller louvre orifice, Mode 1 performs best in term of air velocity distribution, and Turbulence Kinetic Energy (TKE) intensity due to turbulence flow generated at louvre arrangement and complement the effect of pressure drop across the plate. Mode 1 enhances the performance of the HRV system by increasing the percentage of air distribution across the plate with an approximation of 97%.