Thermal and electromagnetic analysis of a 200 kVA transformer with heat pipe cooling

Abstract

Integrating copper wicked heat pipes (CWHPs) is a proven method to improve oil immersed power transformer (OIP/transformer) heat dissipation. However, determining the most effective placement and number of the heat pipes, and addressing electrical and magnetic constraints associated with the heat pipes integration remains a challenge. This study combines numerical modeling of a 200 kVA OIP/transformer with experimental analysis of a CWHP’s performance to identify the most suitable number and arrangement of CWHPs. Results show that the replacement of cooling fins with 58 CWHPs – even before optimizing their placements − decreases hot-spot temperature (HS/temperature) by 9.8 °C. Besides thermal performance, numerical modeling was conducted to assess the potential electrical and magnetic impacts of the CWHPs, demonstrating almost no negative effects on the OIP/transformer in this sense. However, small eddy currents induced in CWHPs by magnetic field fluctuations generate a very tiny extra heat loss of 0.799 W, an insignificant figure compared to the total 2986 W dissipated heat by active components. Generally, using 28 CWHPs located distant from active components provides optimum temperature reduction in HS/temperature by 14.3%. This will significantly enhance the insulation life of windings as well as the reliability of the OIP/transformer. The results of this article demonstrate the practicability and effectiveness of utilizing CWHPs as a thermal management system for OIP/transformers.