Development and experimental analysis of a novel hybrid cooling concept for electric vehicle batteries

Abstract

In this thesis, a novel hybrid cooling concept for electric batteries is developed and studied at both the cell-level and pack-level experiments. The concept is based on a simple air-cooling duct that utilizes enhanced water vaporization by convection to achieve an effective cooling. A series of hydrophilic fiber channels containing a water coolant is exposed to a forced air coolant to extract the latent heat from the battery. Air-cooling and water-cooling methods are also studied to compare and prove the cooling performance. From the test results, the hybrid cooling showed a much greater potential for battery packs with higher energy and power density. At the cell level, the contacted hybrid cooling method was able to decrease the highest temperature rise by 82.9%, 69.6%, and 57.3% compared to that of the no-cooling, the air-cooling, and the water-cooling tests, respectively; and the temperature decreased by 60.9% and 47.0% compared to the air- and water-cooling respectively for the contactless hybrid cooling. The maximum cell-level temperature non-uniformity by the contacted and contactless hybrid cooling tests are 4 ℃. and 2℃, respectively. At the pack level, the contactless hybrid cooling provided more than 70% improvement in both the cooling efficiency and the temperature uniformity compared to the no-cooling baseline.