Co-simulation of HVAC Equipment and Airflow

Common modeling practices for vapor-compression heat pumps assume that the air for the conditioned room is well-mixed. We constructed a simulation using computational fluid dynamics that couples the detailed behavior of the refrigerant cycle to a distributed airflow model, and found that there are important discrepancies between this model and a model using the well-mixed assumption. In particular, the distributed airflow model counterintuitively predicts that the ability of the cycle to cool down the room decreases as the flow rate of air increases for some ranges of parameters. Further analysis shows that this behavior is correct, and is important to consider when designing control systems for the heat pump.