## THERMAL SCIENCE

International Scientific Journal

### Thermal Science - Online First

online first only
### Novel approach to analytical modelling of steady-state heat transfer from the exterior of TEFC induction motors

**ABSTRACT**

The purpose of this paper is to propose a novel approach to analytical modelling of steady-state heat transfer from the exterior of totally enclosed fan-cooled (TEFC) induction motors. The proposed approach is based on the geometry simplification methods, energy balance equation, modified correlations for forced convection, the Stefan-Boltzmann law, air-flow velocity profiles and turbulence factor models. To apply modified correlations for forced convection, the motor exterior is presented with surfaces of elementary 3D shapes as well as the air-flow velocity profiles and turbulence factor models are introduced. The existing correlations for forced convection from a short horizontal cylinder and correlations for heat transfer from straight fins (as well as inter-fin surfaces) in axial air-flows are modified by introducing the Prandtl number to the appropriate power. The correlations for forced convection from straight fins and inter-fin surfaces are derived from the existing ones for combined heat transfer (due to forced convection and radiation) by using the forced-convection correlations for a single flat plate. Employing the proposed analytical approach, satisfactory agreement is obtained with experimental data from other studies.

**KEYWORDS**

PAPER SUBMITTED: 2015-06-26

PAPER REVISED: 2016-04-22

PAPER ACCEPTED: 2016-04-22

PUBLISHED ONLINE: 2016-05-08

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