High performance cooling of a HVDC converter using a fatty acid ester‐based phase change dispersion in a heat sink with double‐layer oblique‐crossed ribs

Qi Li,Chuan Li,Ernesto Mura,Yulong Ding,Ludger Fischer,Geng Qiao

doi:10.1002/er.5347

Abstract

The paper concerns with a high performance cooling method for a HVDC converter using fatty acid ester-based phase change dispersion (PCD) in a heat sink with double-layer oblique-crossed ribs. Thermo-physical properties of PCDs were first characterized under both solid and liquid states, and the cooling performance of the heat exchanger was then experimentally examined, by heating two copper blocks clamped closely to the aluminium heating surfaces. A three-dimensional Euler-Euler multiphase approach was further performed to evaluate the thermal performance under different operating conditions including heating power, flowrate and PCD concentration. The results showed that the viscosity of PCD can be a 100 times that of water, but the increased pumping power was only ~17.01% on average. The use of the PCD achieved a lower temperature of heat sink and fluid than that of water under the same set of conditions due to the latent heat of the PCM, thus enabling a safer and cooler environment for temperature-sensitive HVDC components such as insulated gate bipolar transistors (IGBT). An optimal set of working conditions was proposed and a flowrate of 8 L/min under a heating power of 1.1 kW and a PCM concentration of 25% was recommended for industrial cooling operations.

Highlights

Rapid growing demand for electric power and continuous effort of miniaturization of high-voltage direct current (HVDC) devices drive heat flux to the megawatt range.[1,2] In a high power transmission system, devices such as HVDC converters that transform alternating current (AC) to direct current (DC) and vice versa via controllable electric switches, high power dissipation can be up to 9.72 kW, which is nearly 30% of the total HVDC power loss.[3,4] Under such a high dissipation, sensitive power semiconductor devices such as insulated gate bipolar transistor (IGBT) in the HVDC converter could experience a heat flux over 2 MW/m25 and a temperature increase to 90C,6 depending on the source voltage and switching frequency
It is noteworthy that the viscosity of phase change dispersion (PCD) can be 10 times that of water during phase change, the pressure drop only increased by 17.01% on average under the studied conditions
The work detailed in this paper concerns with a highperformance cooling method for a HVDC converter using fatty acid ester-based phase change dispersion (PCD) in a heat sink with double-layer oblique-crossed ribs

Summary

Introduction

Rapid growing demand for electric power and continuous effort of miniaturization of high-voltage direct current (HVDC) devices drive heat flux to the megawatt range.[1,2] In a high power transmission system, devices such as HVDC converters that transform alternating current (AC) to direct current (DC) and vice versa via controllable electric switches, high power dissipation can be up to 9.72 kW, which is nearly 30% of the total HVDC power loss.[3,4] Under such a high dissipation, sensitive power semiconductor devices such as insulated gate bipolar transistor (IGBT) in the HVDC converter could experience a heat flux over 2 MW/m25 and a temperature increase to 90C,6 depending on the source voltage and switching frequency. The discrepancies of heat sink and fluid temperatures caused by different PCM particle sizes (1-7 μm) are very small (less than ±0.05 K), and the medium particle size d = 3.5 μm will be used for the following thermal analysis.

Results

Conclusion