A Thermal Resistance Model for Problems Involving Chemical Reactions and Phase Transition

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Yoash Mor ◽  
Alon Gany
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Thermal Resistance ◽  
Chemical Reactions ◽  
Heat Sources ◽  
Resistance Model ◽  
Resistance Approach ◽  
Transfer Problems ◽  
Thermal Resistors ◽  
Steady Heat

This paper formulates a modified thermal resistance model (MTRM) for dealing with heat transfer situations involving heat sources from chemical reactions or phase transition. The modified thermal resistance model describes the various heat transfer mechanisms by three common thermal resistors, radiation, convection, and conduction (in media with no internal mass diffusion), adding a new coupled thermal resistor that stands for conduction and enthalpy flow in the gas phase. Similarly to the classical thermal resistance approach, the present model is valid for one-dimensional, quasi-steady heat transfer problems, but it can also handle problems with an internal chemical heat generation source. The new thermal resistance approach can be a useful modular tool for solving relatively easily and quickly complex problems involving chemical reactions and phase transition, such as combustion problems.

Turbulent Heat Transfer Between a Series of Parallel Plates With Surface-Mounted Discrete Heat Sources

1994 ◽  
Vol 116 (3) ◽  
pp. 577-587 ◽  
Author(s):  
S. H. Kim ◽  
N. K. Anand
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Electronic Equipment ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Computational Domain ◽  
Heat Sources ◽  
Parallel Plates ◽  
Wide Range ◽  
Independent Parameters

Two-dimensional turbulent heat transfer between a series of parallel plates with surface mounted discrete block heat sources was studied numerically. The computational domain was subjected to periodic conditions in the streamwise direction and repeated conditions in the cross-stream direction (Double Cyclic). The second source term was included in the energy equation to facilitate the correct prediction of a periodically fully developed temperature field. These channels resemble cooling passages in electronic equipment. The k–ε model was used for turbulent closure and calculations were made for a wide range of independent parameters (Re, Ks/Kf, s/w, d/w, and h/w). The governing equations were solved by using a finite volume technique. The numerical procedure and implementation of the k–ε model was validated by comparing numerical predictions with published experimental data (Wirtz and Chen, 1991; Sparrow et al., 1982) for a single channel with several surface mounted blocks. Computations were performed for a wide range of Reynolds numbers (5 × 104–4 × 105) and geometric parameters and for Pr = 0.7. Substrate conduction was found to reduce the block temperature by redistributing the heat flux and to reduce the overall thermal resistance of the module. It was also found that the increase in the Reynolds number decreased the thermal resistance. The study showed that the substrate conduction can be an important parameter in the design and analysis of cooling channels of electronic equipment. Finally, correlations for the friction factor (f) and average thermal resistance (R) in terms of independent parameters were developed.

Piston-Liner Thermal Resistance Model for Diesel Engine Simulation: Part 1: Formulation and Tuning

1991 ◽  
Vol 205 (5) ◽  
pp. 343-352 ◽  
Author(s):  
Y Rasihhan ◽  
F J Wallace
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Thermal Resistance ◽  
Direct Injection ◽  
Transfer Model ◽  
Conductive Heat ◽  
Axially Symmetric ◽  
Engine Simulation ◽  
Axial Movement ◽  
Resistance Model

A simple, effective and computationally economical piston-liner thermal resistance model for diesel engine simulation is described. In the model, the detailed shape of the piston and its axial movement and interaction with liner nodes are all taken into account. An imaginary node within the piston provides the necessary temperature difference between the piston and the liner nodes for conductive heat transfer, which is expected to reverse its direction with liner insulation. In the liner, an axially symmetric two-dimensional heat-transfer model is used. Later the piston-liner model is tuned for the experimental single cylinder, direct injection, Petter PH 1W engine used at Bath University, against the experimental piston temperature and liner temperature distribution.

A Simple Thermal Resistance Model for Open Cell Metal Foams

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Pradeep. M. Kamath ◽  
C. Balaji ◽  
S. P. Venkateshan
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Convective Heat Transfer Coefficient ◽  
Vertical Channel ◽  
Metal Foams ◽  
Experimental Results ◽  
Actual Case ◽  
Open Cell ◽  
Resistance Model

This paper presents a methodology for obtaining the convective heat transfer coefficient from the wall of a heated aluminium plate, placed in a vertical channel filled with open cell metal foams. For accomplishing this, a thermal resistance model from literature for metal foams is suitably modified to account for contact resistance. The contact resistance is then evaluated using the experimental results. A correlation for the estimation of the contact resistance as a function of the pertinent parameters, based on the above approach is developed. The model is first validated with experimental results in literature for the asymptotic case of negligible contact resistance. A parametric study of the effect of different foam parameters on the heat transfer is reported with and without the presence of contact resistance. The significance of the effect of contact resistance in the mixed convection and forced convection regimes is discussed. The procedure to employ the present methodology in an actual case is demonstrated and verified with additional, independent experimental data.

scholarly journals An integral transform applied to solve the steady heat transfer problem in the half-plane

2017 ◽  
Vol 21 (suppl. 1) ◽  
pp. 105-111
Author(s):  
Tongqiang Xia ◽  
Shengping Yan ◽  
Xin Liang ◽  
Pengjun Zhang ◽  
Chun Liu
Keyword(s):  
Heat Transfer ◽  
Half Plane ◽  
Laplace Equation ◽  
Integral Transform ◽  
Transfer Problem ◽  
Heat Transfer Problem ◽  
Linear Heat ◽  
Transfer Problems ◽  
Steady Heat

An integral transform operator U[?(t)= 1/? ???? ?(t)?-i?t dt is considered to solve the steady heat transfer problem in this paper. The analytic technique is illustrated to be applicable in the solution of a 1-D Laplace equation in the half-plane. The results are interesting as well as potentially useful in the linear heat transfer problems.

scholarly journals A non-field analytical method for heat transfer problems through a moving boundary

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vladimir Kulish ◽  
Vladimír Horák
Keyword(s):  
Heat Transfer ◽  
Chemical Reactions ◽  
Analytical Method ◽  
Moving Boundary ◽  
Front Propagation ◽  
Final Part ◽  
Important Type ◽  
Propagation Law ◽  
Transfer Problems

AbstractThis paper presents an extension of the non-field analytical method—known as the method of Kulish—to solving heat transfer problems in domains with a moving boundary. This is an important type of problems with various applications in different areas of science. Among these are heat transfer due to chemical reactions, ignition and explosions, combustion, and many others. The general form of the non-field solution has been obtained for the case of an arbitrarily moving boundary. After that some particular cases of the solution are considered. Among them are such cases as the boundary speed changing linearly, parabolically, exponentially, and polynomially. Whenever possible, the solutions thus obtained have been compared with known solutions. The final part of the paper is devoted to determination of the front propagation law in Stefan-type problems at large times. Asymptotic solutions have been found for several important cases of the front propagation.

scholarly journals The integrating factor method for solving the steady heat transfer problems in fractal media

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 729-733
Author(s):  
Shan-Xiong Chen ◽  
Zhi-Hao Tang ◽  
Hai-Ning Wang
Keyword(s):  
Heat Transfer ◽  
Fractional Derivative ◽  
Integrating Factor ◽  
Factor Method ◽  
Fractal Media ◽  
Transfer Equations ◽  
Constant Coefficients ◽  
Transfer Problems ◽  
First Time ◽  
Steady Heat

In this paper, we propose the integrating factor method via local fractional derivative for the first time. We use the proposed method to handle the steady heat-transfer equations in fractal media with the constant coefficients. Finally, we discuss the non-differentiable behaviors of fractal heat-transfer problems.

Effects of Substrate Conductivity on Convective Cooling of Electronic Components

1994 ◽  
Vol 116 (3) ◽  
pp. 198-205 ◽  
Author(s):  
C. Y. Choi ◽  
S. J. Kim ◽  
A. Ortega
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Maximum Temperature ◽  
Dimensionless Temperature ◽  
Heat Sources ◽  
Flow Conditions ◽  
Conductive Materials ◽  
Simple Boundary ◽  
Transfer Problems

The coupled conduction and forced convection transport from substrate-mounted modules in a channel is numerically investigated to identify the effects of the substrate conductivity. The results presented apply to air and two-dimensional laminar flow conditions. It was found that recirculating cells as well as streamwise conduction through the substrate play an important role in predicting convective heat transfer from the printed circuit board (PCB) and modules and in determining the temperature distributions in the PCB, modules, and fluid. The dimensionless temperature and the local Nusselt number along the interface between the fluid and the module or PCB are rather complicated, and therefore, predetermined simple boundary conditions along the solid surface may be inappropriate in many conjugate heat transfer problems. In general, the results show that the maximum temperature within heat sources can be greatly reduced by increasing the conductivity of the PCB. The effectiveness of the use of highly conductive materials for PCB, however, depends on the distance between the heat generating modules on the PCB. In addition, finite thermal resistance between the module and the PCB would serve to diminish the PCB conduction effects, thereby reducing the effectiveness of the enhancement afforded by increased conductivity.

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