Performance characteristics of the direct spray oil cooling system for a driving motor of an electric vehicle

In the present work, the performance characteristics of direct spray oil cooling system with spiral, and two full cone nozzles and three cooling oils of mineral oil, dielectric oil and transmission oil are ex-perimentally investigated. The temperature, temperature uniformity, injection pressure, spray resistance, heat transfer coefficient, Nusselt number and spray power consumption are evaluated as the performance characteristics of direct spray oil cooling system. The influences of heating capacities of 1.3 kW and 2.6 kW, nozzle to heating surface distances of 3 cm, 5 cm and 8 cm and cooling oil flow rates of 2 LPM, 3 LPM and 4 LPM are studied on the performance characteristics of direct spray oil cooling system. The lowest maximum surface temperature is obtained for spiral nozzle with 5 cm distance and both full cone nozzles with 8 cm distance. The maximum temperature is maintained within 140 & DEG;C at low heating ca-pacity of 1.3 kW and different combinations of nozzles and cooling oils are tested considering flow rate range of 2 LPM to 4 LPM to maintain the maximum temperature within cut-off limit of 200 & DEG;C at high heating capacity of 2.6 kW. The maximum performance characteristics are obtained at 4 LPM flow rate followed by 3 LPM and 2 LPM flow rates, respectively in decreasing order. The dielectric oil shows supe-rior performance characteristics compared to mineral oil and transmission oil for all nozzles. Furthermore, in each case of cooling oil, the performance characteristics are excellent for full cone-1 nozzle compared to spiral and full cone-2 nozzles. The combination of dielectric oil and full cone-1 nozzle shows superior performance characteristics of direct spray oil cooling system with heat transfer coefficient of 67420.20 W/m2-K, Nusselt number of 2385.64, spray resistance of 0.0132 K/W and spray power consumption of 29.73 W. The data base generated for a direct spray oil cooling system will be implemented for cooling of an electric vehicle driving motor.(c) 2022 Elsevier Ltd. All rights reserved.