Numerical study on improving the thermal performance of an electric motor of an oil pump using an earth air heat exchanger (EAHE).

Abstract

High temperatures in electric motors are a major cause of reduced efficiency and shortened lifespan. To mitigate this problem, an earth air heat exchanger can be used as an effective cooling system. This research investigates improving the thermal performance of electric motors by analyzing the effect of pipe length. Five pipe lengths (10 m, 30 m, 50 m, 70 m, and 90 m) and three inlet temperatures (30°C, 40 °C, and 50 °C) were selected, with a constant mass flow rate of 0.6 kg/s and a constant diameter of 6 in, to determine cooling efficiency. The results showed that rising tube length led to a significant improvement in cooling, with the heat exchanger exit temperature decreasing more at longer lengths. This is attributed to the larger surface area for heat transfer. Larger lengths are associated with higher pressure differentials and greater pumping capacity. Despite this, the longest length performed best, achieving the highest cooling efficiency, with a reduction in motor temperature of approximately 4.75%, 7. 33%, 8. 28%, 8.60%, and 11.21% for pipe lengths of 10 m, 30 m, 50 m, 70 m, and 90 m, respectively. This means that the greater the length, the greater the drop in temperature, resulting in higher system efficiency.