scholarly journals Heat Transfer and Thermal Management of Interior Permanent Magnet Synchronous Electric Motor

Inventions ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 69
Author(s):  
Pey-Shey Wu ◽  
Min-Fu Hsieh ◽  
Wei Ling Cai ◽  
Jen-Hsiang Liu ◽  
Yun-Ting Huang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Electric Motor ◽  
Thermal Field ◽  
Water Jacket ◽  
Taylor Flow ◽  
Nusselt Numbers ◽  
Fluid Analysis ◽  
Interior Permanent Magnet ◽  
Thermal Fluid Analysis ◽  
Spiral Channel

Geometric complexities and multi-physical phenomena add difficulties for predicting the thermal field and hence thermal management of an electric motor. A numerical design model that combined electromagnetic and thermal-fluid analysis was proposed for disclosing the detailed temperature distributions of each component in an electric motor. The thermal fluid analysis implemented ANSYS-Fluent code to unravel the thermal field of the interior permanent magnet synchronous electric motor fitted with a smooth or novel spirally twisted channel in the cooling water jacket of a stator with and without shaft cooling. In accordance with the thermal powers converted from the various electromagnetic losses of the electric motor, the complex heat conduction model with realistic thermal boundary conditions was formulated. Initially, the turbulent flow structures and channel averaged Nusselt numbers of the spiral channels without and with the sectional twist were comparatively examined for acquiring the convective thermal boundary conditions in the water jacket. With the high thermal conductivity of the aluminum water jacket, the heat-transfer improvements from the smooth-spiral-channel conditions by using the twisted spiral channel were effective for reducing the average temperatures by about 10% but less effective for altering the characteristic thermal field in the water jacket. At 1290 < Dn < 6455 or 5000 < Re < 25,000 for the spiral channel flows, the channel average Nusselt numbers ratios between the smooth and twisted spiral channels were elevated to 1.18–1.09 but decreased with the increase of Dn or Re. A set of heat-transfer correlations for estimating the Nusselt numbers of Taylor flow in the rotor-to-stator air gap was newly devised from the data available in the literature. While the cooling effectiveness of the water jacket and shaft was boosted by the sectional twists along the spiral channel of the water jacket, the presence of Taylor flow in the annual air gap prohibited the effective rotor-to-stator heat transmission, leading to hot spots in the rotor. By way of airflow cooling through the rotating hollow shaft, the high temperatures in the rotor were considerably moderated. As the development of Taylor flow between the rotor and stator was inevitable, the development of active or passive rotor cooling schemes was necessary for extending the power density of an electric motor. Unlike the previous thermal circuit or lumped-parameter thermal model that predicted the overall temperatures of motor components, the present coupled electromagnetic and thermal-fluid model can reveal the detailed temperature distributions in an electric motor to probe the local hot spots of each component in order to avoid overheating at the early design stage.

scholarly journals Evaluation of localized heat transfer coefficient for induction heating apparatus by thermal fluid analysis based on the HSMAC method

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 504-511
Author(s):  
Satoshi Namiki ◽  
Tomoya Iino ◽  
Yoshifumi Okamoto
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Conduction ◽  
Transfer Coefficient ◽  
Induction Heating ◽  
Thermal Design ◽  
Electrical Machines ◽  
Fluid Analysis ◽  
Thermal Fluid Analysis ◽  
The Heat Transfer Coefficient

AbstractWith the development of electrical machines for achieving higher performance and smaller size, heat generation in electrical machines has also increased. Consequently, the temperature rise in electrical machines causes unexpected heating of components and makes it difficult to operate properly. Therefore, in the development of electrical machines, the accurate evaluation of temperature increase is important. In the thermal design of electrical machines, heat-conduction analysis using the heat-transfer boundary set on the surface of a heated target has been frequently performed. However, because the heat-transfer coefficient is dependent on various factors, it is often determined based on experimental or numerical simulation results. Therefore, setting the heat-transfer coefficient to a constant value for the surface of the heated target degrades the analysis accuracy because the actual phenomenon cannot be modeled. To enhance the accuracy of the heat-transfer coefficient, the coupled electromagnetic field with heat-conduction analysis finite element method (FEM), thermal-fluid analysis using FEM, and the highly simplified marker and cell method is applied to the estimation of the distribution of the heat-transfer coefficient. Moreover, to accurately calculate the localized heat-transfer coefficient, the temperature distribution and flow velocity distribution around the heated target are analyzed in the induction-heating apparatus.

Numerical Study on Thermal Field in Concrete with Cooling Pipe Based on the Coupling Method

2011 ◽  
Vol 94-96 ◽  
pp. 388-392 ◽  
Author(s):  
Yu Lin Lu ◽  
Tao Lu ◽  
Li Wang ◽  
Zhen Yu Wang ◽  
Pei Pei Zhao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Thermal Field ◽  
Numerical Study ◽  
Thermal Characteristics ◽  
Nusselt Numbers ◽  
Cooling Pipe ◽  
The Mean ◽  
Transfer Method ◽  
Structure Engineering

A finite element method was developed to reveal the thermal characteristics of concrete with a cooling pipe, and the influence of cooling pipe on thermal field was calculated by the coupled fluid flow and solid heat transfer method. Temperature distribution along the pipeline was calculated and the mean Nusselt numbers on each section in the cooling pipe also were obtained. Numerical results show that the flow field and the temperature distribution were very complexly and the heat transfer was severely attenuated in the bend position, the outboard temperature of pipe was higher than the inboard temperature. In addition, in order to study the effect of the cooling pipe on thermal distribution, the temperature of different positions at the hydration time were compared with the no cooling results. The present results could be helpful to predict the temperature cracks in structure engineering.

Heat Transfer in a Surfactant Drag-Reducing Solution—A Comparison With Predictions for Laminar Flow

2005 ◽  
Vol 128 (6) ◽  
pp. 557-563 ◽  
Author(s):  
Paul L. Sears ◽  
Libing Yang
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Reynolds Numbers ◽  
High Heat ◽  
High Heat Flux ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Drag Reducing Additive ◽  
Good Agreement

Heat transfer coefficients were measured for a solution of surfactant drag-reducing additive in the entrance region of a uniformly heated horizontal cylindrical pipe with Reynolds numbers from 25,000 to 140,000 and temperatures from 30to70°C. In the absence of circumferential buoyancy effects, the measured Nusselt numbers were found to be in good agreement with theoretical results for laminar flow. Buoyancy effects, manifested as substantially higher Nusselt numbers, were seen in experiments carried out at high heat flux.

Effects of Insulated and Isothermal Baffles on Pseudosteady-State Natural Convection Inside Spherical Containers

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Yuping Duan ◽  
S. F. Hosseinizadeh ◽  
J. M. Khodadadi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Numerical Procedure ◽  
Boussinesq Approximation ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Extended Surface ◽  
Parametric Studies ◽  
Thermal Layer

The effects of insulated and isothermal thin baffles on pseudosteady-state natural convection within spherical containers were studied computationally. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables. Natural convection effect is modeled via the Boussinesq approximation. Parametric studies were performed for a Prandtl number of 0.7. For Rayleigh numbers of 104, 105, 106, and 107, baffles with three lengths positioned at five different locations were investigated (120 cases). The fluid that is heated adjacent to the sphere rises replacing the colder fluid, which sinks downward through the stratified stable thermal layer. For high Ra number cases, the hot fluid at the bottom of the sphere is also observed to rise along the symmetry axis and encounter the sinking colder fluid, thus causing oscillations in the temperature and flow fields. Due to flow obstruction (blockage or confinement) effect of baffles and also because of the extra heating afforded by the isothermal baffle, multi-cell recirculating vortices are observed. This additional heat is directly linked to creation of another recirculating vortex next to the baffle. In effect, hot fluid is directed into the center of the sphere disrupting thermal stratified layers. For the majority of the baffles investigated, the Nusselt numbers were generally lower than the reference cases with no baffle. The extent of heat transfer modification depends on Ra, length, and location of the extended surface. With an insulated baffle, the lowest amount of absorbed heat corresponds to a baffle positioned horizontally. Placing a baffle near the top of the sphere for high Ra number cases can lead to heat transfer enhancement that is linked to disturbance of the thermal boundary layer. With isothermal baffles, heat transfer enhancement is achieved for a baffle placed near the bottom of the sphere due to interaction of the counterclockwise rotating vortex and the stratified layer. For some high Ra cases, strong fluctuations of the flow and thermal fields indicating departure from the pseudosteady-state were observed.

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