A Study on the Determination of Supply Airflow Rate and Temperature of VAV Terminal Unit Using CFD Simulation

The purpose of this study is to determine appropriate combinations of supply airflow rate and supply air temperature that maintain the target indoor temperature without causing thermal stratification while minimizing energy consumption through CFD modeling. A laboratory at Y University was modeled using the Fire Dynamics Simulator (FDS). The CFD model was validated against field-measured indoor temperature data, and a Cv(RMSE) of 15.78% was obtained. The simulations were conducted under different heating-load conditions by varying the supply airflow rate and supply air temperature. As a result, 171 operating cases satisfying both the target indoor temperature range of 20–22 °C and the absence of thermal stratification were identified. The energy analysis showed that, even under similar room-load conditions, total energy consumption differed by up to 41.70% depending on the combination of supply airflow rate and supply air temperature. Based on the minimum-energy conditions, this study provides load-dependent guidelines for determining supply airflow rate and supply air temperature while considering both the indoor thermal environment and energy consumption. However, this study was limited to a single laboratory under winter heating conditions, and the energy analysis considered fan power and reheat energy; therefore, further validation under different spaces and operating conditions is required.