Experimental investigation of cell arrangement, spacing, and airflow in a forced-air-cooled battery thermal management system for cylindrical lithium-ion cells

This study presents an experimental investigation of a forced air-cooled battery thermal management system designed for a module consisting of six cylindrical lithium-ion cells connected in series. The aim is to address the existing gap in achieving both cost-effective and efficient thermal management for battery modules. Accordingly, a widely used air-cooling system was examined through a comprehensive set of experiments. The effects of battery array configurations, cell spacing, and mass flow rate on maximum temperature, temperature uniformity, pressure drop, cooling efficiency, and parasitic power consumption were analyzed. Among the investigated layouts, the 3–3 in-line configuration provided the lowest maximum temperature and pressure drop, reducing the maximum temperature by approximately 4 °C compared with the 2–2–2 arrangement at 3C. For the selected 3–3 configuration, a longitudinal spacing of S L = 28.3 mm and a transverse spacing of S T = 38.3 mm provided the most favorable balance between thermal performance, temperature uniformity, occupied area, and flow resistance, with a cooling efficiency of 9.39 °C/Pa at 3C. Increasing the air mass flow rate from 0.019 to 0.026 kg/s reduced the maximum temperature from 31.7 °C to 28.97 °C and substantially improved temperature uniformity; however, the associated increases in fan power and pressure drop reduced the overall benefit. Consequently, 0.024 kg/s was identified as the most balanced operating point, yielding dimensionless maximum temperature and temperature difference values of 0.72 and 0.59, respectively, with a pressure drop of 2.4 Pa and a parasitic power ratio of 1.61%. Finally, under high-load conditions, the BTMS provided partial thermal control at 4C, although the 35 °C limit was exceeded, while 5C resulted in a rapid temperature increase to 46.64 °C and was found unsuitable for safe operation.