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Air-Gap Heat Transfer in Rotating Electrical Machines: A Parametric Study
Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Corporate Research, Västerås, Sweden.ORCID iD: 0000-0002-9490-9703
Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Corporate Research, Västerås, Sweden.ORCID iD: 0000-0001-8849-7661
2017 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, p. 4176-4181Article in journal (Refereed) Published
Abstract [en]

More than half of all electrical energy is consumed by motors and generators in an industrialized country. About 5-25% of this energy is lost and converted to heat. This heat produced by the losses has adverse effect on the lifetime and performance of a machine. A machine has to be operated at a given temperature to achieve maximum efficiency, therefore heat transfer study of machines is of special interest to rotating machines manufacturers. In this paper we investigate the heat transfer in the air-gap between the rotor and the stator of a simplified induction motor using Computational Fluid Dynamics. We consider three different air-gap widths and rotation speeds to explore the change in air-gap heat transfer when changing the air-gap width and the rotation speed. The simulated average heat transfer coefficients for all the models are in good agreement with the correlations from published literature. The Taylor-Couette vortical flow pattern is observed in the air-gap in our simulation results for the models with large air-gaps. The numerical results show that the presence of Taylor-Couette vortices in the air-gap enhance the heat transfer. The heat transfer coefficient increases with the increase in the rotation speed and decreases with the decrease in the air-gap width. 

Place, publisher, year, edition, pages
Elsevier Ltd , 2017. Vol. 142, p. 4176-4181
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-38716DOI: 10.1016/j.egypro.2017.12.343ISI: 000452901604055Scopus ID: 2-s2.0-85041542591OAI: oai:DiVA.org:mdh-38716DiVA, id: diva2:1186819
Available from: 2018-03-01 Created: 2018-03-01 Last updated: 2019-01-03Bibliographically approved
In thesis
1. Fluid Flow and Heat Transfer Simulations for Complex Industrial Applications: From Reynolds Averaged Navier-Stokes towards Smoothed Particle Hydrodynamics
Open this publication in new window or tab >>Fluid Flow and Heat Transfer Simulations for Complex Industrial Applications: From Reynolds Averaged Navier-Stokes towards Smoothed Particle Hydrodynamics
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Optimal process control can significantly enhance energy efficiency of heating and cooling processes in many industries. Process control systems typically rely on measurements and so called grey or black box models that are based mainly on empirical correlations, in which the transient characteristics and their influence on the control parameters are often ignored. A robust and reliable numerical technique, to solve fluid flow and heat transfer problems, such as computational fluid dynamics (CFD), which is capable of providing a detailed understanding of the multiple underlying physical phenomena, is a necessity for optimization, decision support and diagnostics of complex industrial systems. The thesis focuses on performing high-fidelity CFD simulations of a wide range of industrial applications to highlight and understand the complex nonlinear coupling between the fluid flow and heat transfer. The industrial applications studied in this thesis include cooling and heating processes in a hot rolling steel plant, electric motors, heat exchangers and sloshing inside a ship carrying liquefied natural gas. The goal is to identify the difficulties and challenges to be met when simulating these applications using different CFD tools and methods and to discuss the strengths and limitations of the different tools.

The mesh-based finite volume CFD solver ANSYS Fluent is employed to acquire detailed and accurate solutions of each application and to highlight challenges and limitations. The limitations of conventional mesh-based CFD tools are exposed when attempting to resolve the multiple space and time scales involved in large industrial processes. Therefore, a mesh-free particle method, smoothed particle hydrodynamics (SPH) is identified in this thesis as an alternative to overcome some of the observed limitations of the mesh-based solvers. SPH is introduced to simulate some of the selected cases to understand the challenges and highlight the limitations. The thesis also contributes to the development of SPH by implementing the energy equation into an open-source SPH flow solver to solve thermal problems. The thesis highlights the current state of different CFD approaches towards complex industrial applications and discusses the future development possibilities.

The overall observations, based on the industrial problems addressed in this thesis, can serve as decision tool for industries to select an appropriate numerical method or tool for solving problems within the presented context. The analysis and discussions also serve as a basis for further development and research to shed light on the use of CFD simulations for improved process control, optimization and diagnostics.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2018
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 282
Keywords
Computational Fluid Dynamics, Heat transfer, Industrial applications, Reynolds Averaged Navier-Stokes, Smoothed Particle Hydrodynamics, Energy enginnering, Thermal Management, Process control
National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-41277 (URN)978-91-7485-415-2 (ISBN)
Public defence
2018-12-14, Delta, Mälardalens högskola, Västerås, 13:00 (English)
Opponent
Supervisors
Available from: 2018-11-02 Created: 2018-11-01 Last updated: 2018-11-12Bibliographically approved

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Hosain, Md LokmanBel Fdhila, Rebei

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