Exact temperature field in a slab with time varying ambient temperature and time-dependent heat transfer coefficient

2017 ◽  
Vol 116 ◽  
pp. 82-90 ◽  
Author(s):  
Te Wen Tu ◽  
Sen Yung Lee
2000 ◽  
Vol 122 (4) ◽  
pp. 792-800 ◽  
Author(s):  
P. S. Wei ◽  
F. B. Yeh

The heat transfer coefficient at the bottom surface of a splat rapidly solidified on a cold substrate is self-consistently and quantitatively investigated. Provided that the boundary condition at the bottom surface of the splat is specified by introducing the obtained heat transfer coefficient, solutions of the splat can be conveniently obtained without solving the substrate. In this work, the solidification front in the splat is governed by nonequilibrium kinetics while the melting front in the substrate undergoes equilibrium phase change. By solving one-dimensional unsteady heat conduction equations and accounting for distinct properties between phases and splat and substrate, the results show that the time-dependent heat transfer coefficient or Biot number can be divided into five regimes: liquid splat-solid substrate, liquid splat-liquid substrate, nucleation of splat, solid splat-solid substrate, and solid splat-liquid substrate. The Biot number at the bottom surface of the splat during liquid splat cooling increases and nucleation time decreases with increasing contact Biot number, density ratio, and solid conductivity of the substrate, and decreasing specific heat ratio. Decreases in melting temperature and liquid conductivity of the substrate and increase in latent heat ratio further decrease the Biot number at the bottom surface of the splat after the substrate becomes molten. Time-dependent Biot number at the bottom surface of the splat is obtained from a scale analysis. [S0022-1481(00)01004-5]


Author(s):  
С.В. Бородкин ◽  
А.В. Иванов ◽  
И.Л. Батаронов ◽  
А.В. Кретинин

На основе уравнений теплопереноса в движущейся среде и соотношений теплопередачи в термоэлектрическом охладителе приведен сравнительный анализ методик расчета поля температуры в теплонапряженном элементе. Рассмотрены методики на основе: 1) теплового баланса, 2) среднего коэффициента теплоотдачи, 3) дифференциального коэффициента теплоотдачи, 4) прямого расчета в рамках метода конечных элементов. Установлено, что первые две методики не дают адекватного распределения поля температур, но могут быть полезны для определения принципиальной возможности заданного охлаждения с использованием термоэлектрических элементов. Последние две методики позволяют корректно рассчитать температурное поле, но для использования третьей методики необходим дифференциальный коэффициент теплоотдачи, который может быть найден из расчета по четвертой методике. Сделан вывод о необходимости комбинированного использования методик в общем случае. Методы теплового баланса и среднего коэффициента теплоотдачи позволяют определить принципиальную возможность использования термоэлектрического охлаждения конкретного теплонапряженного элемента (ТЭ). Реальные параметры системы охлаждения должны определяться в рамках комбинации методов дифференциального коэффициента теплоотдачи и конечных элементов (МКЭ). Первый из них позволяет определить теплонапряженные области и рассчитать параметры системы охлаждения, которые обеспечивают тепловую разгрузку этих областей. Второй метод используется для проведения численных экспериментов по определению коэффициента теплоотдачи реальной конструкции The article presents on the basis of the equations of heat transfer in a moving medium and the relations of heat transfer in a thermoelectric cooler, a comparative analysis of methods for calculating the temperature field in a heat-stressed element. We considered methods based on: 1) heat balance, 2) average heat transfer coefficient, 3) differential heat transfer coefficient, 4) direct calculation using the finite element method. We established that the first two methods do not provide an adequate distribution of the temperature field but can be useful for determining the principal possibility of a given cooling using thermoelectric elements. The last two methods allow us to correctly calculate the temperature field; but to use the third method, we need a differential heat transfer coefficient, which can be found from the calculation using the fourth method. We made a conclusion about the need for combined use of methods in a general case. The methods of thermal balance and average heat transfer coefficient allow us to determine the principal possibility of using thermoelectric cooling of a specific heat-stressed element. The actual parameters of the cooling system should be determined using a combination of the differential heat transfer coefficient and the finite element method. The first of them allows us to determine the heat-stressed areas and calculate the parameters of the cooling system that provide thermal discharge of these areas. The second method is used to perform numerical experiments to determine the heat transfer coefficient of a real structure


2014 ◽  
Vol 644-650 ◽  
pp. 459-462
Author(s):  
Yao Ye ◽  
Feng Wang ◽  
Yong Hai Wu

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.


2003 ◽  
Vol 27 (9) ◽  
pp. 795-811 ◽  
Author(s):  
Periklis E. Ergatis ◽  
Panagiotis G. Massouros ◽  
Georgia C. Athanasouli ◽  
George P. Massouros

2013 ◽  
Vol 448-453 ◽  
pp. 3316-3319
Author(s):  
Chuang Sun ◽  
Yang Zhao ◽  
De Fu Li ◽  
Qing Ai ◽  
Xin Lin Xia

According to the view of heat transfer, the process of the fluid flow with high temperature and high speed over a flat plate may be considered as the heat transfer process within a compressible thermal boundary layer. Based on the numerical results of thermal isolation assumption, combining the temperature comparison with modification method, a coupled method of convection heat transfer coefficient with temperature field of the plate is established, and the characteristics of the thermal response for the flat plate is dominated. Take some ribbed plates as instances, the convection heat transfer coefficient and temperature field of the plate are simulated through the provided coupled method. The results show that, not only the position and materials of the plate influence the convection heat transfer coefficient, but also the time.


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