Dew-point aware dynamic evaporation pressure control for condensation suppression in direct cooling EV battery systems

Refrigerant direct cooling is an attractive option for electric-vehicle battery thermal management but remains prone to surface condensation on the cold plate under hot–humid conditions, with implications for durability and efficiency. This work develops a calibrated vehicle-level model of a transcritical CO₂ system to quantify condensate formation, battery thermal response and system performance, and proposes a dew-point-aware control that dynamically regulates the cold-plate evaporation pressure independently of the cabin loop. The model (validated against bench data with deviations ≤6% in compressor power, heat-exchanger duty and effective COP after stabilization) is used to map ambient temperature–humidity effects and reveal that coupling between the cold-plate and cabin evaporating temperatures is the primary driver of excessive condensation in conventional equal-pressure architectures. Under representative hot–humid conditions, setting the cold-plate evaporation temperature near the ambient dew point suppresses condensation while avoiding over-penalization of cooling efficiency. Compared with constant-pressure operation, the proposed strategy maintains battery temperature targets and passenger comfort, reduces condensate mass by 68.8% and lowers total compressor power by 5.4%. The results provide implementable guidance for decoupled evaporation-pressure control in CO₂ battery direct-cooling systems and support safe, efficient operation across diverse climates.