HVDC Converter Cooling System with a Phase Change Dispersion

Ludger Fischer,Geng Qiao,Poppy O’Neill,Ernesto Mura,Qi Li,Silvan Von Arx,Yulong Ding

doi:10.3390/fluids6030117

Abstract

High voltage direct current converters require efficient cooling of thyristors via heat sinks. Currently, infrastructures use deionised water as a means of cooling the high voltage direct current converters; however, recent research has shown that other fluids have potential to offer more efficient cooling. Phase change dispersions are a new class of heat transfer fluids that employ the latent heat of phase change, thus offering isothermal cooling during melting. For cooling applications, the temperature increase during operation is thus lowered when using phase change dispersions (compared to water) and consequently, the heat sink and thyristors surface temperatures are reduced. In this investigation, a phase change dispersion with non-conductive components, high stability, high capacity and low viscosity has been developed and tested. An experimental setup of a real size heat sink has been installed and the heat transfer behaviour of both the formulated phase change dispersion and water have been investigated and a comparison has been presented. Using water as the heat transfer fluid, the temperature increase from inlet to outlet of the heat sink was 4 K and with the formulated phase change dispersion (at the same mass flow rate and heat input) the temperature increase was 2 K. The phase change dispersion caused a 50% reduction in the heat sink surface temperature. Furthermore, the global heat transfer coefficients obtained for the phase change dispersion were found to be independent of the heating input applied, unlike the trend found for water, additionally, the global heat transfer coefficients were found to be similar to those obtained for water at the same mass flow rates and reached a maximum value of 6100 W m2 K−1. Despite this, the pressure drops and viscosities obtained for the phase change dispersion were higher than for water. Overall, the current investigation demonstrates the ability of using a phase change dispersion as a cooling fluid for the cooling of electronic components, which thus far is limited to using air and water cooling and cannot reach the cooling capacity achieved by phase change dispersions.

Highlights

For the generation of electricity from renewable sources, such as wind and photovoltaics, two technical topics need to be addressed: the time shifted production and the consumption, which can be diurnal or seasonal [1]
The aim of this paper is to propose a large increment of the heat transfer in the cooling of a sensitive component of high voltage direct current (HVDC) converters such as the thyristor, by proposing a new cooling fluid that can be implemented without any structural change of the cooling system
The results highlight that the use of the PCD in the system reduced the temperature increase in comparison to water by 50%

Summary

Introduction

For the generation of electricity from renewable sources, such as wind and photovoltaics, two technical topics need to be addressed: the time shifted production and the consumption, which can be diurnal or seasonal [1]. This issue will be part of seasonal storages, Power-to-X and multi energy grid scenarios. Long-distance electrical grids will use high voltage direct current (HVDC) transmission to minimise the energy losses as discussed by May et al [2] and Nguyen and Saha [3]. The production of renewable energies at remote locations, such as wind farms in the

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Methods

Conclusion