A model for the estimation of the refrigerant flow distribution and an experimental study on the integrated thermal management system of electric vehicles

With the rapid growth and advancements in electric vehicles (EVs), the thermal management technology for the entire vehicle has progressively evolved towards greater integration and refinement. This evolution places heightened expectations on the precise control and energy-efficient utilization of multiple systems, including the battery thermal management system (BTMS) and air conditioning (AC), among others. In this paper, we propose an aggregate tendency method aimed at tracing the distribution characteristics of refrigerant flow in multi-cooling systems. This method is designed to provide fundamental target regulation parameters for the main control quantities based on the cooling capacity demands of both the battery and the AC. First, the relationship between the cooling capacity demands of parallel circuits is analyzed, and a mathematical model of compressor speed and refrigerant flow distribution is established. Subsequently, by introducing flow distribution coefficients (ω_r) and extrapolating the main control quantities, a trend quantification of regulation is obtained. The validation results indicate that the model possesses good predictive accuracy. Finally, considering the typical dynamic driving conditions of vehicles, the pre-adjustment target of the thermal management system is established. Additionally, the joint regulation schemes for synchronous and asynchronous control of the compressor and VOVs (compressor priority and VOVs priority) are investigated. The results indicate that prioritizing these control schemes achieves a balance between the battery cooling response and the air temperature fluctuations of the AC.