scholarly journals Experimental and numerical investigation of thermal field for a motor and related factors sensitivities using combined CFD-Taguchi method

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1065-1077
Author(s):  
Xueqi Liang ◽  
Huiqiang Luo ◽  
Min Zeng ◽  
Yining Wu ◽  
Qiuwang Wang
Keyword(s):  
Thermal Conductivity ◽  
Sensitivity Analysis ◽  
Taguchi Method ◽  
Ambient Temperature ◽  
Temperature Rise ◽  
Convection Heat Transfer ◽  
Axial Direction ◽  
Experimental Result ◽  
Related Factors ◽  
Copper Loss

Over-temperature is a fatal problem when a motor is running. In this work, the temperature and temperature rise of the motor are investigated experimentally and numerically. The experiment is conducted by means of both voltmeter-ammeter method and embedding thermal resistors, to obtain the mean temperature and the local temperature of the stator coils, respectively. The numerical calculation is carried out to study the temperature field of the stator and the rotor, which agrees well with the experimental result. What?s more, the sensitivity analysis of eighteen factors to the temperature is investigated using combined CFD-Taguchi method. The main conclusions are drawn. Firstly, according to the numerical results, the maximal temperature and the maximal temperature rise at rated speed are 143? and 99 K, respectively. The values are 145.8? and 90 K, according to the experimental results, which are lower than the temperature allowed, 180? and temperature rise allowed, 125 K. Secondly, the sensitivity analysis results suggest that the key factors influencing the temperature are in sequence the ambient temperature, the copper loss, the thickness of the layers, the outside convection heat transfer coefficient of crate, the iron loss at the tooth and thermal conductivity of the insulation. The contact thermal resistance and the thermal conductivity of the core in axial direction have little influence on the temperature. The rank to the temperature rise is similar except the ambient temperature, which has little effect on the temperature rise.

Beam Heating in Election Irradiated Foils

1974 ◽  
Vol 32 ◽  
pp. 562-563
Author(s):  
H. P. Leighly ◽  
D. E. Campbell ◽  
J. J. Laidler
Keyword(s):  
Thermal Conductivity ◽  
Electron Microscope ◽  
Energy Loss ◽  
Ambient Temperature ◽  
Temperature Rise ◽  
Beam Energy ◽  
Beam Intensity ◽  
Beam Radius ◽  
Beam Heating

Fisher developed an expression for the loss of energy in electron microscope foils. This expression utilizes a theory of Bethe's to describe the energy loss for electrons in a solid. Fisher obtained the following relationship: ΔΤαΙ ρ/k in which ΔΤ is the temperature rise above the ambient temperature, ρ° is density of the foil, k is thermal conductivity, and IO is beam intensity. By using this expression with IO = 1020e/cm2 /sec, he calculated the very substantial heating of foils of various metallic and nonmetallic materials as a function of beam radius, distance to the nearest conductor, and beam energy; i. e., iron has a 2000°C temperature rise for a 10-micron beam, 0.1-MeV electrons, and 900-micron distance to the nearest conductor.

Effect of load type on temperature rise of a disc brake

2014 ◽  
Vol 5 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Qing-rui Meng
Keyword(s):  
Contact Pressure ◽  
Temperature Rise ◽  
Axial Direction ◽  
Sine Wave ◽  
Practical Application ◽  
Ansys Software ◽  
Content Type ◽  
Load Types ◽  
Load Simulation ◽  
Contact Pressures

Purpose – The purpose of this paper is to reveal the temperature rise characteristics of the disc and pads under different load types. Design/methodology/approach – Evolutions of the disc and pads temperature under a stable, gradual changing and sine-wave contact pressures widely used at present are analyzed numerically by using ANSYS software. Findings – The results show that during the loading process, the temperature increases most rapidly under a stable contact pressure, most slowly under a gradual changing contact pressure; the disc temperature rise curves expose saw-shaped character, the closer it is to the friction surface, the more serious the fluctuations will be, the pads temperature rise curves are rather smooth; temperature gradient in the axial direction is higher than that in the other two directions under all of the three types of contact pressure and shows a sine-wave variation under a sine-wave contact pressure. Originality/value – It indicates that a gradual changing contact pressure should be adopted preferentially in practical application. The simulation results of this work provide theoretical basis for load simulation.

scholarly journals Low Reynolds number flow in a heated tube of varying section

1983 ◽  
Vol 25 (2) ◽  
pp. 244-260 ◽  
Author(s):  
A. R. Bestman
Keyword(s):  
Reynolds Number ◽  
Free Convection ◽  
Asymptotic Series ◽  
Convection Heat Transfer ◽  
Axial Direction ◽  
Reynolds Number Flow ◽  
Free Convection Heat ◽  
Number Flow ◽  
Convection Parameter ◽  
Constricted Tube

AbstractIn this paper we study the effect of forced and free convection heat transfer on flow in an axisymmctric tube whose radius varies slowly in the axial direction. Asymptotic series expansions in terms of a small parameter ∈, which is a measure of the radius variation, are obtained for the velocity components, pressure and temperature on the assumption that the Reynolds number (R) is of order one. The effect of the free convection parameter or Grashof number (G) on the axial velocity, temperature distribution, shear stress and heat flux at the wall are discussed quantitatively for a locally constricted tube.

scholarly journals Life-Cycle Break-Even Analysis of Electric Carsharing: A Comparative Study in China

2020 ◽  
Vol 12 (16) ◽  
pp. 6584
Author(s):  
Jingjing Jia ◽  
Shujie Ma ◽  
Yixi Xue ◽  
Deyang Kong
Keyword(s):  
Sensitivity Analysis ◽  
Life Cycle ◽  
Life Cycle Cost ◽  
Net Present Value ◽  
Market Price ◽  
Critical Factor ◽  
Field Investigation ◽  
Related Factors ◽  
Business To Consumer ◽  
Influential Variable

Electric carsharing (ECS) is a potential option to address the problem of unsustainability in the transportation sector. The business-to-consumer model of ECS, which is one of several different electric carsharing models, has gained much popularity in recent years. Generating sufficient revenue to cover costs is a critical factor for ECS companies to maintain healthy development. This study makes an economic analysis, on the basis of life-cycle cost and monetary revenue associated with the operation of ECS, of two Chinese ECS companies: EVCARD and LCCS. Based on data gathered by field investigation, this study aims to determine the break-even moment for each company’s main vehicle models by means of the net present value method. The results show that EVCARD achieved an earlier break-even moment than LCCS. The break-even moment of Chery eQ of EVCARD was the shortest of all the vehicle models, at only 181.3 min. Moreover, a sensitivity analysis was conducted to portray how different cost-related and revenue-related factors influence the break-even moment. Our findings indicate that a wide difference exists in terms of the influence of different factors on the break-even moment. Among these, the manufacturer’s suggested retail price is the most influential variable, followed by the unit rental price. The reaction of the break-even moment to the market price of a charging pile and the non-rental revenue per vehicle—especially the latter—was found to be negligible in the sensitivity analysis.

scholarly journals Thermal Analysis of AlGaN/GaN HEMTs Considering Anisotropic And Inhomogeneous Thermal Conductivity

2021 ◽  
Author(s):  
Yao Li ◽  
Zixuan Zheng ◽  
Qun Li ◽  
Hongbin Pu
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Power Dissipation ◽  
Thermal Characteristics ◽  
Maximum Temperature ◽  
Base Temperature ◽  
Initial Growth ◽  
Boltzmann Transport ◽  
Growth Interface ◽  
Anisotropic Thermal Conductivity

Abstract To examine the differences of thermal characteristics introduced by material thermal conductivity, anisotropic polycrystalline diamond (PCD) and GaN are analyzed based on the accurate model of grain sizes in the directions of parallel and vertical to the interface and an approximate solution of the phonon Boltzmann transport equation. Due to the space-variant grain structures of PCD, the inhomogeneous-anisotropic local thermal conductivity, homogeneous-anisotropic thermal conductivity averaged over the whole layer and the typical values of inhomogeneous-isotropic thermal conductivity are compared with/without anisotropic GaN thermal conductivity. The results show that the considerations of inhomogeneous-anisotropic PCD thermal conductivity and anisotropic GaN thermal conductivity are necessary for the accurate prediction of temperature rise in the GaN HEMT devices, and when ignoring both, the maximum temperature rise is undervalued by over 16 K for thermal boundary resistance (TBR) of 6.5 to 60 m2K/GW at power dissipation of 10 W/mm. Then the dependences of channel temperature on several parameters are discussed and the relations of thermal resistance with power dissipation are extracted at different base temperature. Compared with GaN, SiC and Si substrates, PCD is the most effective heat spreading layer though limited by the grain size at initial growth interface.

scholarly journals Thermal Conductivity of Lightweight Concrete Block with Various Cooling Agent

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
Masni A. Majid ◽  
◽  
Aina Syafawati Roslan ◽  
Noor Azlina Abdul Hamid ◽  
Norhafizah Salleh ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Consumption ◽  
Energy Demand ◽  
Lightweight Concrete ◽  
Human Life ◽  
Concrete Block ◽  
Experimental Result ◽  
Cooling Agent ◽  
Reduce Energy Consumption ◽  
Day By Day

Energy was the important sources to human life. Due to increases energy demand in daily life, the energy consumption was increase day by day because of the heat load from solar radiation and heat produced by people. Toward sustainable development, this research was carried out to develop a lightweight concrete (LWC) block with various cooling agent such as glycerine, propylene glycol, coconut shell and gypsum powder. Six lightweight concrete (LWC) block with the size 250mm (L) × 250mm (W) × 100mm (T) were tested for thermal conductivity value. From the experimental result, it shows that lightweight concrete (LCW) block with various cooling agent obtained thermal conductivity value of 0.17W/mK - 0.36W/mK lower than thermal conductivity value for normal lightweight concrete (0.8W/mK) depending on concrete density. The lightweight concrete (LCW) block with cooling agent having low thermal conductivity value will reduce energy consumption in building.

Effects of Stone-Wales Defects on the Thermal Conductivity of Carbon Nanotubes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Li Wei ◽  
Feng Yanhui ◽  
Peng Jia ◽  
Zhang Xinxin
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Temperature Profile ◽  
Defect Position ◽  
Non Equilibrium Molecular Dynamics ◽  
Increasing Temperature ◽  
Dynamics Method

The thermal conductivity of carbon nanotubes with Stone-Wales (SW) defects was investigated using non-equilibrium molecular dynamics method. The defect effects were analyzed by the temperature profile and local thermal resistance of the nanotubes with one or more SW defects and further compared with perfect tubes. The influences of the defect concentration, the length, the chirality and the radius of tubes and the ambient temperature were studied. It was demonstrated that a sharp jump in the temperature profile occurred at defect position due to a higher local thermal resistance, thus dramatically reducing the thermal conductivity of the nanotube. As the number of SW defects increases, the thermal conductivity decreases. Relative to the chirality, the radius has greater effects on the thermal conductivity of tubes with SW defects. With the similar radius, the thermal conductivity of armchair nanotube is higher than that of zigzag one. The shorter nanotube is more sensitive to the defect than the longer one. Thermal conductivity of the nanotube increases with ambient temperature, reaches a peak, and then decreases with increasing temperature.

High-Temperature PbTe Thin Films for Use in Cascade Thermoelectric Power Generation

2003 ◽  
Vol 793 ◽  
Author(s):  
J.B. Posthill ◽  
J.C. Caylor ◽  
P.D. Crocco ◽  
T.S. Colpitts ◽  
R. Venkatasubramanian
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Power Generation ◽  
High Temperature ◽  
Ambient Temperature ◽  
Thermoelectric Power ◽  
Thermal Evaporation ◽  
Potential Candidate ◽  
Substrate Orientation ◽  
Subtle Effect

ABSTRACTPbTe-based thin films were deposited by thermal evaporation at temperatures ranging from ambient temperature to 430°C on different vicinal GaAs (100) substrates and BaF2 (111). This materials system is being evaluated as a potential candidate thermoelectric material for a mid-temperature stage in a cascade power generation module. Pure PbTe, PbSe, and multilayer PbTe/PbSe films were investigated. All films deposited on different vicinal GaAs (100) substrates were found to be polycrystalline when deposited at 250°C or lower. A subtle effect of substrate orientation and multilayer periodicity appears to contribute to the more randomly oriented polycrystallinity, which also lowers the thermal conductivity. These results are compared with PbTe epitaxial results on BaF2 (111).

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