1D and 3D Coupled Thermal Simulation of HVAC at Defrost Mode Using Dual Stream Heat Exchanger Model

<div class="section abstract"><div class="htmlview paragraph">In today's fast-paced lifestyle, people spend a maximum amount of time for traveling, leading to a heightened demand for thermal comfort. Automotive HVAC play a crucial role in providing conditioned air to ensure comfort while traveling. Evaluating HVAC systems performance including delivery systems, heat exchanger efficiency, air thermal mixing zones, and temperature distribution are essential to maintain fuel economy and modern vehicle styling. However, accurately predicting cooling/heating performance using CFD simulations poses challenges due to the complex nature of heat exchanger modeling, which demands substantial computational resources and time.</div><div class="htmlview paragraph">This paper presents the development of CFD modeling capabilities for predicting temperature distribution at duct outlet grills for defrost mode. Additionally, it assesses heater performance under maximum hot conditions. STAR-CCM+ software is employed to model the entire system, with the heater and evaporator core represented as porous regions. The inertial and viscous resistances in these regions are defined using Coil Designer 1-D simulation result data which includes air side pressure drop at different airflow rates for both heater and evaporator.</div><div class="htmlview paragraph">A dual stream heat exchanger model within STAR-CCM+ is utilized to create the heater topology and establish a heater interface between two fluid regions. One-dimensional simulation result data from the heater, showcasing heat transfer at various airflow rates with a water flow rate of 6 LPM, is imported into the dual stream heat exchanger model. The dual stream heat exchanger methodology enables comprehensive system unit simulation with significantly reduced computational costs and faster solving times.</div></div>