Abstract：To improve the thermal performance of finned tube oil cooler, an improved method applying elliptical tube with multiunit fin (louvered fin and vortex generator with rectangular shaped winglet at the rear of tube) was proposed. Based on the kε turbulence model, the velocity, temperature and pressure distribution of the finned tube and the multiunit finned tube were calculated and achieved by threedimensional numerical simulation. The thermal performance of the finned tube and the multiunit finned tube were compared using the comprehensive evaluation factor JF. The results show that the heat transfer factor j and friction factor f of the multiunit finned tube are both significantly higher than those of the finned tube in the range of Reynolds number from 550 to 2 100. The factor j is increased by 1.64 to 1.79 times, and f is increased by 1.69 to 1.71 times. The JF factor is increased by 37.8% to 49.6%. A larger increasing of JF factor corresponds to a lower Reynolds number, and a smaller increase corresponds to a higher Reynolds number. The thermal performance of the multiunit finned tube is superior to that of the finned tube.
