scholarly journals Heat Transfer Scale Effect Analysis and Parameter Measurement of an Electrothermal Microgripper

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 309
Author(s):  
Lin Lin ◽  
Hao Wu ◽  
Liwei Xue ◽  
Hao Shen ◽  
Haibo Huang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Scale Effect ◽  
Convective Heat Transfer Coefficient ◽  
Simulation Software ◽  
Field Analysis ◽  
Heat Transfer Analysis ◽  
Effect Analysis ◽  
Microscale Heat Transfer ◽  
Transfer Parameters

An electrothermal microgripper is an important actuator in microelectromechanical and micro-operating systems, and its temperature field analysis is the core problem in research and design. Because of the small size of an electrothermal microgripper, its microscale heat transfer characteristics are different from those of the macrostate. At present, only a few studies on the heat transfer scale effect in electrothermal microgrippers have been conducted, and the heat transfer analysis method under the macrostate is often used directly. The temperature field analysed and simulated is different from the actual situation. In the present study, the heat transfer mechanism of an electrothermal microgripper in the microscale was analysed. The temperature field of a series of microscale heating devices was measured using microthermal imaging equipment, and the heat transfer parameters of the microscale were fitted. Results show that the natural convective heat transfer coefficient of air on the microscale can reach 60–300 times that on the macroscale, which is an important heat transfer mode affecting the temperature field distribution of the electrothermal microgripper. Combined with the finite element simulation software, the temperature field of the electrothermal microgripper could be accurately simulated using the experimental microscale heat transfer parameters measured. This study provides an important theoretical basis and data support for the optimal design of the temperature controller of the electrothermal microgripper.

The Temperature Field Research of an Engine Cylinder Liner Based on ANSYS

2014 ◽  
Vol 644-650 ◽  
pp. 459-462
Author(s):  
Yao Ye ◽  
Feng Wang ◽  
Yong Hai Wu
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer Coefficient ◽  
Field Research ◽  
Cylinder Liner ◽  
Element Model ◽  
Engine Cylinder ◽  
Engine Cylinder Liner

The temperature field of cylinder liner directly affects the working process of the engine cylinder. Its research is an important research direction of the engine research. We analysis the location relationship between the cylinder liner and cooperate with the components analysis in this paper. Then the finite element model of cylinder liner component is established and boundary conditions such as gas convective heat transfer coefficient, the piston top heat transfer coefficient are analyzed. A certain type of engine cylinder liner is calculated by using ANSYS temperature field equation solvers. The model and the calculation method this article uses are of great significance for the temperature field research of other heat transfer components.

Numerical Assessment on Time-Varying Temperature Field of Bridge Tower under Solar Radiation

2012 ◽  
Vol 204-208 ◽  
pp. 2236-2239 ◽  
Author(s):  
Bo Chen ◽  
Wei Hua Guo ◽  
Chun Fang Song ◽  
Kai Kai Lu
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Ambient Air ◽  
Heat Transfer Analysis ◽  
Time Varying ◽  
Long Span ◽  
Bridge Tower

Bridge tower, time-varying temperature field, heat transfer analysis, finite element model. Abstract. Long span suspension bridges are subjected to daily, seasonal and yearly environmental thermal effects induced by solar radiation and ambient air temperature. This paper aims to investigate the temperature distribution of a tower of a long span suspension bridge. Two-dimensional heat transfer models are utilized to determine the time-dependent temperature distribution of the bridge tower of the bridge. The solar radiation model is utilized to examine the time-varying temperature distribution. Finite element models are constructed for the bridge tower to compute the temperature distribution. The numerical models can successfully predict the structural temperature field at different time. The methodology employed in the paper can be applied to other long-span bridges as well.

Influence factors on bulk temperature field of gear

2016 ◽  
Vol 231 (8) ◽  
pp. 953-964 ◽  
Author(s):  
Biao Luo ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Convective Heat Transfer Coefficient ◽  
Influence Factors ◽  
Practical Method ◽  
Lubricating Oil ◽  
Bulk Temperature ◽  
Curvature Radius ◽  
Ultimate Cause ◽  
Tooth Surfaces

The convective heat transfer coefficient of different tooth surfaces and the friction heat flux were identified based on the theory of tribology, heat transfer, and gear meshing theory. A more accurate parametric model of finite element thermal analysis of a single tooth was established by using APDL and the more accurate bulk temperature field of the gear was obtained. The factors that affect the bulk temperature field of gears were also analyzed, and the influence mechanism of each factor was carried out. The results show that high-pressure angle and tooth profile modification cannot only effectively reduce the bulk temperature of the gear, but also benefits the distribution of the bulk temperature. Long-addendum gear is beneficial to the distribution of the bulk temperature. The bulk temperature is proportional to the initial temperature of the lubricating oil. The variations of the equivalent curvature radius, the stiffness and the load sharing ratio of the meshing point are the ultimate cause of the change of the bulk temperature. The results of this paper can provide a more accurate and practical method for obtaining the bulk temperature of the gear, and it also can provide a theoretical basis and method to improve the thermal behavior of gears.

Inverse Heat Transfer Analysis of Porous Extended Surface Using Simplex Search Method

2013 ◽  
Author(s):  
Rohit Kumar Singla ◽  
Ranjan Das ◽  
Arka Bhowmik ◽  
Ramjee Repaka
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Measurement ◽  
Thermal Conditions ◽  
Search Method ◽  
Heat Transfer Analysis ◽  
Critical Parameters ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Extended Surface

This work deals with the application of the Nelder-Mead simplex search method (SSM) to study a porous extended surface. At first, analytical expression for calculating the local temperature field has been derived using an implicit Runge-Kutta method. The heat transfer phenomenon is assumed to be governed by conductive, naturally convective and radiative heat transfer, whereas the diffusion of mass through the porous media is also taken into account. Then, using the SSM, critical parameters such as porosity, permeability, and thermal conductivities of the extended surface have been predicted for satisfying a prescribed temperature field. It is found that many alternative solutions can meet a given thermal requirement, which is proposed to offer the flexibility in selecting the material and regulating the thermal conditions. It is observed that the allowable error in the temperature measurement should be limited within 5%. It is also found that even with few temperature measurement points, very good reconstruction of the thermal field is possible using the SSM.

Investigation of Heat Transfer Efficiency of Improved Intermig Impellers in a Stirred Tank Equipped with Vertical Tubes

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Leizhi Wang ◽  
Yongjun Zhou ◽  
Zhaobo Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Heat Exchange ◽  
Convective Heat Transfer Coefficient ◽  
Simulation Software ◽  
Related Factors ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Vertical Tubes

AbstractThe heat transfer of a reactor with improved Intermig impellers was numerically investigated by the finite element method (FEM) simulation software Fluent (V.19). A turbulence model utilized the standard k-ε model, and the turbulent flows in two large vortexes between vertical tubes were collided to form a strong convection. The influence of heat and mass transfer developing from the impeller diameters, the distance between the two impellers (C1), the rotational speed and the installation height of the bottom impeller (C2) were studied. The reactor was equipped with special structure vertical tubes to increase the heat exchange areas. The rate of heat transfer, including criteria such as the convective heat transfer coefficient, the Nusselt number of outside vertical tubes, and the temperature boundary layer thickness, assured the accurate control of the heat exchange mixing state. The experimental testing platform was designed to validate the simulated results, which revealed the influence order of related factors. The Nusselt number Nu was affected by various related factors, resulting in the rotation and diameter of impellers extending far beyond the distance between the two impellers (C1) and the installation height of the impeller (C2). The average temperature boundary layer thicknesses of the symmetrical and middle sections were 3.24 mm and 3.48 mm, respectively. Adjusting the appropriate parameters can accurately control the heat exchange process in such a reactor, and the conclusions provide a significant reference for engineering applications.

Heat Transfer and Thermal Load Analysis of Exhaust Manifold

2012 ◽  
Vol 226-228 ◽  
pp. 2240-2244 ◽  
Author(s):  
Shi Long Xu ◽  
Yan Shi ◽  
Shou Cheng Li
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Alloy Steel ◽  
Thermal Load ◽  
Convective Heat Transfer Coefficient ◽  
Heat Transfer Analysis ◽  
Nonlinear Material ◽  
Joint Analysis ◽  
Deformation Analysis ◽  
Exhaust Manifold

With the appearance of high temperature resistance alloy steel and the requirement of light weight for vehicles, more and more exhaust manifolds are made from newly developed alloy steel. The changing of material directly affects the design and manufacturing process. To estimate the thermal load of the tight-coupled exhaust manifold, the joint analysis methods of CFD and FEM are put forward to predict the temperature distribution, thermal stress and deformation. Using Computational Fluid Dynamics (CFD) method, gas temperature and convective heat transfer coefficient, adjoining the inside and outside surfaces of the exhaust manifold, are estimated firstly in this paper. Then these results are mapped to the finite element mesh of exhaust manifold, which are created for the heat transfer analysis. At last, thermal stress and thermal deformation analysis are presented by taking nonlinear material properties into account, which provide some reference to evaluate the cooling capacity and structure design of exhaust manifold.

Determination of convective heat transfer coefficient for hot gas torch (HGT)-assisted automated fiber placement (AFP) for thermoplastic composites

2021 ◽  
pp. 089270572098236
Author(s):  
Lorenz Zacherl ◽  
Farjad Shadmehri ◽  
Klemens Rother
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heat Transfer Analysis ◽  
Thermoplastic Composites ◽  
Hot Gas ◽  
Automated Fiber Placement

In-situ manufacturing of thermoplastic composites using the automated fiber placement (AFP) process consists of heating, consolidation and solidification steps. During the heating step using hot gas torch (HGT) as a moving heat source, the incoming tape and the substrate are heated up to a temperature above the melting point of the thermoplastic matrix. The convective heat transfer occurs between the hot gas flow and the composites in which the convective heat transfer coefficient h plays an important role in the heat transfer mechanism which in turn significantly affects temperature distribution along the length, width and through the thickness of the deposited layers. Temperature is the most important process parameter in AFP in-situ consolidation that affects bonding quality, crystallization and consolidation. Although it is well known the convective heat transfer coefficient h is not constant and has a distribution, most studies have assumed a constant value for h for heat transfer analysis which leads to discrepancy between numerical and experimental results. In this study a new function is proposed to approximate the distribution of the convective heat transfer coefficient h in the vicinity of the nip point. Using the proposed convective heat transfer coefficient distribution, a three-dimensional finite element transient heat transfer analysis is performed to predict temperature distribution in the composite parts. An optimization loop is employed to find the free parameters of the distribution function so that the predicted temperature match experimental data. It is shown that, unlike other studies assuming constant h value, not only maximum temperature can be well predicted, but also predicted heating and cooling curves agree well with experimental results. The cooling rate is of significant importance in crystallization behavior and residual stress calculation.

Experimental investigation and numerical simulation of weld bead geometry and temperature distribution during plasma arc welding of thin Ti-6Al-4V sheets

2016 ◽  
Vol 52 (1) ◽  
pp. 30-44 ◽  
Author(s):  
V Dhinakaran ◽  
N Siva Shanmugam ◽  
K Sankaranarayanasamy
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Arc Welding ◽  
Convective Heat Transfer Coefficient ◽  
Weld Bead ◽  
Heat Transfer Analysis ◽  
Bead Geometry ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Weld Bead Geometry

Numerical and experimental investigations of autogenous plasma arc welding of thin titanium alloy of 2 mm thick and modelling the temperature distribution for predicting the weld bead geometry are presented. The finite element code COMSOL Multiphysics is employed to perform non-linear unsteady heat transfer analysis using parabolic Gaussian heat source. Temperature-dependent material properties such as thermal conductivity, density and specific heat are used to enhance the efficiency of simulation process. A forced convective heat transfer coefficient was used to account for the effect of convection. The experimental trials were conducted by varying the welding speed and current using Fronius plasma arc welding equipment. The simulation results are in good agreement with the experimental results.

Finite Element Analysis of Temperature Field of Traction Motor

2012 ◽  
Vol 189 ◽  
pp. 461-464
Author(s):  
An Xing Zhu ◽  
Zhi Xiong Yang ◽  
Yi Cui
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Temperature Field ◽  
Convective Heat Transfer Coefficient ◽  
Transient Temperature ◽  
Iron Core ◽  
Field Calculation ◽  
Three Dimension ◽  
Element Analysis ◽  
Traction Motor

Due to the fact of immeasurable inner temperature of inverter-fed traction motor, three-dimension finite element model of part of rotor iron core and half a rotor bearing were established. The convective heat transfer coefficient between the air gap of motor and rotor surface were calculated by the heat transfer and fluid mechanics theory. The influence of temperature rise on the stator and rotor resistance was considered for thermal loss calculation. The influence of the end of stator and rotor on axial temperature distribution was also taken into account. Then three-dimensional transient temperature field of the motor was simulated at the rated load. Temperature field with different loads was also computed. The aim has been to optimize the design with respect to the transient stresses. According to contrastive analysis compared with other method, it demonstrated the accuracy of simulation model and thermal field calculation results.

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