An Evaluation of Heat Transfer Coefficient in an Independent Zonal Temperature Controls with CFD

Abstract This paper introduced a methodology to calculate the heat transfer coefficient between two adjacent air conditioning zones via a virtual wall aims to improve the independent zonal temperature control for a VAV system. The selected room was divided into two subzones with each controlled by 2 square ceiling diffusers mounted on the up-ceiling level. A virtual wall was artificially identified and split into the fluid domain in Fluent. The heat transfer coefficient (HTC) across the virtual wall was derived from the discrete energy equations and obtained by implementing UDFs in the Fluent solver, both the heat transfer due to air mass flows and the heat exchange due to turbulence were considered in the model. A 2-separate VAV control platform was established in TRNSYS and the HTC was fed to the control platform to evaluate the impact of HTC on the temperature control system. The simulation results shown it has an insignificant impact on the controllers, but the temperature on both sides were controlled precisely within the expected range compared with CFD simulation results.