1D Modeling of HVAC Unit Air Flow for Automatic Climate Control Simulations 2021-01-0215

Advanced control techniques are widely used in different automotive applications including climate control. Significant costs associated with the development and calibration of such controllers can be reduced if these tasks are conducted in a virtual environment. Such a virtual environment can be developed by integrating the controller with the system model. Different scenarios can be then simulated to make sure functional objectives of the system are met. 1D models provide the necessary level of accuracy without imposing extra computational cost in such virtual environments. As such, they are perfect candidates for model, hardware or software-in-the loop validation benches for controls. Performance of a heating, ventilation and air-conditioning (HVAC) system can be controlled through the settings of the components like mode door, blend door, recirculation door, blower, and the compressor. In an automatic climate control (ACC) system, these factors are automatically actuated to achieve thermal comfort. For development and calibration of ACC systems, virtual setups with a model of HVAC unit can be used. In this case, the model should capture the flow inside the HVAC unit which could be impacted by the door positions. This paper proposes a 1D model for HVAC unit air flow, where components such as mode door, blend door, recirculation door, and blower are modeled and calibrated. Capability of the model to predict temperature values along the unit is then validated against test data. The promising results demonstrate the model potential in ACC virtual development and calibration. This can reduce the number of tests needed and help minimize the cost, effort, and possible delays in product development.