Determination of Heat Transfer Coefficient from Housing Surface of a Totally Enclosed Fan-Cooled Machine during Passive Cooling

Payam Shams Ghahfarokhi,Hans Tiismus,Andrejs Podgornovs,Anouar Belahcen,Antonio J Marques Cardoso,Toomas Vaimann,Ants Kallaste,Bilal Asad

doi:10.3390/machines9060120

Abstract

This paper presents the analytical calculation of the heat transfer coefficient of a complex housing shape of a Totally Enclosed Fan-Cooled (TEFC) industrial machine when it works below 20% of its nominal speed or close to stall. Therefore, passive cooling is dominant, and most of the heat is extracted by the combination of natural convection and radiation phenomena. Under these conditions, the area-based composite approach was used for the development of the analytical calculation method. A test rig using a TEFC Synchronous Reluctance Motor (SynRM) was constructed, and the collected experimental data was used to validate the proposed analytical method successfully.

Highlights

This study considers the analytical calculation for the electrical machine (EM), which is installed in the horizontal direction
This section mainly focuses on experimental verifications and validation of the analytical method performance for predicting the heat transfer of a Totally Enclosed Fan-Cooled (TEFC) housing machine in passive cooling conditions
The experimental phase is accomplished to validate and check the accuracy of the analytical analysis approach to calculate the heat-transfer coefficient of a TEFC EM in natural cooling

Summary

Introduction

In a TEFC machine for variable speed drives, at low-speed performance or close to stall, the passive cooling is the dominant cooling [1,2]. Heat fluxes are extracted from the housing to the ambient by the mixture of natural convection and radiation phenomena. In the thermal analysis of a TEFC motor, the accurate calculation of these parameters significantly impacts the thermal model accuracy. One of the standard methods to calculate these parameters is the analytical approach. In this approach, the convection and radiation are calculated using empirical correlations based on dimensionless numbers. Depending on the thermal analysis method, these phenomena are demonstrated by the coefficients used either directly or to calculate thermal resistance [3]

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