A methodology to work on geometrically complex heat transfer systems: the cases of heat conduction through composite slabs

2003 ◽  
Vol 46 (18) ◽  
pp. 3397-3409 ◽  
Author(s):  
Wataru Nakayama
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Ryoichi Chiba

An analytical solution is derived for one-dimensional transient heat conduction in a composite slab consisting of n layers, whose heat transfer coefficient on an external boundary is an arbitrary function of time. The composite slab, which has thermal contact resistance at n-1 interfaces, as well as an arbitrary initial temperature distribution and internal heat generation, convectively exchanges heat at the external boundaries with two different time-varying surroundings. To obtain the analytical solution, the shifting function method is first used, which yields new partial differential equations under conventional types of external boundary conditions. The solution for the derived differential equations is then obtained by means of an orthogonal expansion technique. Numerical calculations are performed for two composite slabs, whose heat transfer coefficient on the heated surface is either an exponential or a trigonometric function of time. The numerical results demonstrate the effects of temporal variations in the heat transfer coefficient on the transient temperature field of composite slabs.


Author(s):  
C. P. Howard

The results are presented from a numerical finite-difference method of calculation for the transient behavior of porous media when subjected to a step change in fluid temperature considering the case where the longitudinal thermal heat conduction cannot be neglected. These results, given in tabular and graphical form, provide a useful means for evaluating the heat-transfer data obtained from the transient testing of compact heat-exchanger surfaces.


2015 ◽  
Vol 9 (3) ◽  
pp. 161-166
Author(s):  
Aneta Bohojło-Wiśniewska

Summary This paper presents an example of humid air flow around a single head of Chinese cabbage under conditions of complex heat transfer. This kind of numerical simulation allows us to create a heat and humidity transfer model between the Chinese cabbage and the flowing humid air. The calculations utilize the heat transfer model in porous medium, which includes the temperature difference between the solid (vegetable tissue) and fluid (air) phases of the porous medium. Modelling and calculations were performed in ANSYS Fluent 14.5 software.


2015 ◽  
Vol 17 (25) ◽  
pp. 16476-16482 ◽  
Author(s):  
Liu Cui ◽  
Yanhui Feng ◽  
Peng Tan ◽  
Xinxin Zhang

Theoretical insights into the heat transfer performance and its reduction mechanisms in double-walled carbon nanotubes with intertube additional carbon atoms.


Author(s):  
Fangming Jiang ◽  
Dengying Liu ◽  
Jim S.-J. Chen ◽  
Richard S. Cohen

A novel experimental method was developed to measure the rapid transient temperature variations (heating rate > 107 K/s) of porous samples heated by high surface heat fluxes. With a thin film (0.1 μm thick) resistance thermometer of platinum as the temperature sensor and a super-high speed digital oscilloscope (up to 100 MHz) as the data recorder, rapid transient temperature variation in a porous material heated by a microsecond laser pulse of high power density is measured. Experimental results indicate that for high heat transfer cases (q′ > 109 W/m2) with short durations (5 – 20 μs) of heating, non-Fourier heat conduction behaviors appear. The non-Fourier hyperbolic heat conduction model and the traditional Fourier parabolic model are employed to simulate this thermal case respectively and the FDM is used to perform the numerical analysis. The hyperbolic model predicts thermal wave behavior in qualitative agreement with the experimental data.


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