@misc{9252427,
  abstract     = {{The transition toward battery electric vehicles requires motors with increasingly high power densities, pushing traditional thermal management systems to their limits. This thesis conducts a comparative computational fluid dynamics (CFD) analysis to evaluate the thermal performance of Direct Oil Immersion Cooling versus Indirect Water Jacket Cooling for EV motor stators. CFD simulations were performed on a reference stator motorette using Autodesk CFD. To ensure a fair comparison, both cooling methods were evaluated at a load of 1800 ampere-turns per coil. This entailed using five coil turns for direct cooling and six for indirect cooling, resulting in conductor current densities of 34.0 A/mm² and 25.6 A/mm², respectively, for the same conductor cross-section of 3.8x2.8 mm². This meant that the direct case had a lower copper fill factor, and hence was subjected to a 77% higher volumetric heat generation rate when compared to the indirect case.

Despite this thermal difference and the use of a lower-capacity dielectric fluid, direct oil immersion demonstrated thermal efficiency higher than that of the indirect counterpart. The indirect cooling case hit a rigid thermal ceiling, peaking at a 248.8 °C with a steep internal gradient of 58 °C, fundamentally bottle necked by the conductive resistance. Conversely, direct cooling bypassed these barriers via direct convective heat extraction, capping the maximum temperature at 131.6 °C. Furthermore, it established good thermal uniformity, constraining the internal temperature gradient to a narrow interval of 16 °C to 21 °C. For indirect water cooling, the flow rate is 1.45 L/min and the average flow velocity is 2.14 m/s in a Ø3.8 mm tube, whereas for direct oil cooling, the flow rate is 1.5 L/min and the average flow velocity is 0.435 m/s in a 100.91 mm² cooling channel.}},
  author       = {{Sardar Abdulla, Ali Halbastian and Ilhamoi, Hadi}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{CODEN:LUTEDX/TEIE}},
  title        = {{A CFD Analysis of Thermal Performance: Direct Oil Immersion and Indirect Water Jacket Cooling}},
  year         = {{2026}},
}