Friction Loss and Thermal Analysis of a High-Speed Permanent Magnet Machine for Waste Heat Power Generation Application

Guanghui Du,Na Huang

doi:10.1109/access.2019.2940615

Abstract

R245 medium is predominantly used in high-speed permanent magnet machines (HSPMMs) for waste heat power generation, owing to its low boiling point. However, this results in high friction loss and rotor cooling difficulty due to its high temperature and high mass density. Therefore, this paper focuses on the study of friction loss and temperature characteristics under high temperature and high-mass-density cooling media. First, the power losses are simulated by the corresponding finite element model (FEM), in which the friction losses to air and R245 medium are compared using a computational fluid dynamics (CFD) model. In addition, the temperature characteristics with air and R245 cooling media are compared by fluid-thermal coupling analysis. Finally, a prototype with an output power of 400 kW and rotation speed of 10 000 rpm is fabricated, and the loss and temperature characteristics are tested to validate the effectiveness of the HSPMM analysis.

Highlights

In recent years, owing to increasing demand for high power density, high efficiency, and direct drive, high-speed permanent magnet machines (HSPMMs) have been widely used in applications such as compressors, gas turbines, distributed power generation, and flywheels [1]–[3]
In the design of HSPMMs, permanent magnets (PMs) are likely to suffer from irreversible demagnetization [4], [5], and carbon fibers are hot-rolled at high temperature [6]
The mass density of R245 under high pressure is as high as 10 kg/m3, which is approximately 10 times that of air. When this type of medium is used as the cooling medium, the friction loss would be greatly increased compared to the use of air, which would further increase the difficulty of heat dissipation from the HSPMM

Summary

INTRODUCTION

In recent years, owing to increasing demand for high power density, high efficiency, and direct drive, high-speed permanent magnet machines (HSPMMs) have been widely used in applications such as compressors, gas turbines, distributed power generation, and flywheels [1]–[3]. The hightemperature R245 medium must act as a cooling medium in order to reduce the rotor temperature, which makes it difficult to dissipate heat from the HSPMM [15] Power loss, such as core loss [16], friction loss, can be significantly increased due to high frequency and speed. The mass density of R245 under high pressure is as high as 10 kg/m3, which is approximately 10 times that of air When this type of medium is used as the cooling medium, the friction loss would be greatly increased compared to the use of air, which would further increase the difficulty of heat dissipation from the HSPMM. VOLUME 7, 2019 these challenges of friction loss and thermal characteristics of HSPMMs using a high temperature and density cooling medium for waste heat power generation applications. The measurement and calculated values of the electromagnetic characteristics, power losses, and temperature characteristics are compared in detail, which have validated the effectiveness of the analysis

POWER LOSSES ANALYSIS

EXPERIMENTAL TESTS

Findings

CONCLUSION