More efficient cooling systems are an enabler for the increase in power density in an electric traction motor. Contemplating to existing reviews, this article presents a comprehensive collection of heat transfer mechanisms for the different heat removal techniques used in electric traction motors. In this article, an overview of various cooling concepts in existing and future traction motors is presented, and the cooling approaches are compared. The following literature review compiles geometry-based calculation formulas of the different mechanisms of cooling heat transfer applied in motor technology. Furthermore, general heat transfer phenomena appearing in electric traction motors are reviewed and compiled for easy access. Various specifically relevant aspects, including rotor shaft cooling, different spray cooling concepts, different air convection phenomena, bearing heat transfer, and the stator-housing contact, are examined in more detail. For validation of the review result, based on a well-known motor design, thermal analysis and comparison of the different cooling methods are carried out. Modeling is done with a lumped parameter thermal network (LPTN). This article concludes by demonstrating the advantages and disadvantages of the different cooling concepts based on the collection of modeling data.

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Traction Motor Cooling Systems: A Literature Review and Comparative Study

Fatigue lifetime assessment on a high-pressure heater in supercritical coal-fired power plants during transient processes of operational flexibility regulation

The heat exchanger pipe diameter has a significant effect on the flow characteristics as well as on the initial investment, operation and overall cost. Increasing fin dimensions increases the annulus hydraulic diameters. Even though the total volume of the heat exchanger remains unchanged between the finned and bare designs, the heat duty increases with increased heat transfer area for the finned design. The fins should be designed, and the dimensions should be calculated with special attention for different flow rates and heat exchanger dimensions. In this study, number, geometry and dimensions of the fins are determined using the algorithms available in the literature. The operational condition optimization is carried out accompanied with the cost analysis. In addition, the effects of the types of working fluids and fouled and clean cases are investigated for the total heat transfer enhancement in parallel with performance, lifetime and cost issues. A detailed analysis is presented for finned and unfinned double-pipe heat exchanger models for pure engine oil and its nanofluid mixtures with Ti, TiO2, Cu, CuO, Al and Al2O3 nanoparticles, multi-wall carbon nanotubes and graphene nanosheet having a constant particle concentration in the liquid phase. The nanofluid is flowing in annulus side, whereas the seawater is flowing in the tube side. It is observed that both the pressure drop and the pumping power increase with the increasing fin number and decrease with the cleanliness factor, whereas the total tube number decreases with increasing fin number. It is found that different types of nanofluids affect the cost and optimum annulus side velocity significantly. The results are summarized in several figures that consider the increasing Reynolds number with the cleanliness factor, the heat transfer coefficient and the pressure drop, the friction factor with changing mass flow rate and the cost values with corresponding annulus side velocities. Finally, the overall characteristics of the trend lines are provided in the figures.

Optimization of the finned double-pipe heat exchanger using nanofluids as working fluids

Improved design of heat sink including porous pin fins with different arrangements: A numerical turbulent flow and heat transfer study

A comprehensive review of heat transfer enhancement and flow characteristics in the concentric pipe heat exchanger

Effect of aspect ratio on heat transfer enhancement in alternating oval double pipe heat exchangers

Development of a model to evaluate the water level impact on drain cooling in horizontal high pressure feedwater heaters

A criterion for the effect of parallel mode rotation on non- isothermal flow through square channel

Analysis of air flow and heat transfer in a winding using porous medium approach

The effect of radial flow injection on the heat transfer characteristics of a Taylor–Couette–Poiseuille flow in an annulus is numerically investigated using the SST k-ω turbulence model. Th...

M Sina Karbalaee

Papers

Effect of aspect ratio on heat transfer enhancement in alternating oval double pipe heat exchangers

Development of a model to evaluate the water level impact on drain cooling in horizontal high pressure feedwater heaters

A criterion for the effect of parallel mode rotation on non- isothermal flow through square channel

Analysis of air flow and heat transfer in a winding using porous medium approach

Effect of radial injection on heat transfer of a Taylor-Couette-Poiseuille flow