Applicability of One-Dimensional Transient Solutions for Ground-Coupled Heat Transfer in Buildings

2013 ◽  
Vol 361-363 ◽  
pp. 386-390 ◽  
Author(s):  
J Daniel Mena Baladés ◽  
Ismael Rodríguez Maestre ◽  
Pascual Álvarez Gómez ◽  
J. Luis Foncubierta Blázquez
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Finite Element Software ◽  
Coupled Heat Transfer ◽  
Transient Solutions ◽  
Detailed Simulation ◽  
Different Dimensions ◽  
Multidimensional Effects

The ground-coupled heat transfer in buildings is a complex, transient and multidimensional problem. There have been many studies focused to obtain the heat flux in slab and basement foundations. Most of them include the multidimensional effects occur at the perimeter however there are situations in which the heat transfer is mainly one-dimensional. This paper presents a study that aims to establish the accurate of an analytical one-dimensional solution to estimate the ground-coupled heat transfer. Detailed simulation by using finite element software is used to obtain the total heat flux at indoor surface of the building for a whole year. Typical slabs and basements foundations for different dimensions have been analyzed. A correlation to estimate the relative error is proposed.

Nonlinear Inverse Heat Conduction With a Moving Boundary: Heat Flux and Surface Recession Estimation

1999 ◽  
Vol 121 (3) ◽  
pp. 708-711 ◽  
Author(s):  
V. Petrushevsky ◽  
S. Cohen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fourier Series ◽  
Heat Conduction ◽  
Moving Boundary ◽  
Heat Conduction Problem ◽  
Inverse Heat Conduction Problem ◽  
Variable Order ◽  
Inverse Heat Conduction ◽  
One Dimensional

A one-dimensional, nonlinear inverse heat conduction problem with surface ablation is considered. In-depth temperature measurements are used to restore the heat flux and the surface recession history. The presented method elaborates a whole domain, parameter estimation approach with the heat flux approximated by Fourier series. Two versions of the method are proposed: with a constant order and with a variable order of the Fourier series. The surface recession is found by a direct heat transfer solution under the estimated heat flux.

Measurement of Heat Flux From Fires

Volume 4 ◽  
2004 ◽  
Author(s):  
Cecilia S. Lam ◽  
Alexander L. Brown ◽  
Elizabeth J. Weckman ◽  
Walter Gill
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Unit Area ◽  
Inverse Heat Conduction ◽  
Thermal Impact ◽  
Temperature Changes ◽  
One Dimensional ◽  
Conduction Heat Transfer ◽  
Flux Measurements

Heat flux is an important parameter for characterization of the thermal impact of a fire on its surroundings. However, heat flux cannot be measured directly because it represents the rate of heat transfer to a unit area of surface. Therefore, most heat flux measurements are based on the measurement of temperature changes at or near the surface of interest [1,2]. Some instruments, such as the Gardon gauge [3] and the thermopile [2], measure the temperature difference between a surface and a heat sink. In radiation-dominated environments, this difference in temperature is often assumed to be linearly related to the incident heat flux. Other sensors measure a surface and/or interior temperature and inverse heat conduction methods frequently must be employed to calculate the corresponding heat flux [1,4]. Typical assumptions include one-dimensional conduction heat transfer and negligible heat loss from the surface. The thermal properties of the gauge materials must be known and, since these properties are functions of temperature, the problem often becomes non-linear.

Coupled heat transfer through an alveolar structure heated by a uniform heat flux

2019 ◽  
Vol 13 ◽  
pp. 931-938
Author(s):  
B. Jamal ◽  
M. Boukendil ◽  
A. Abdelbaki ◽  
Z. Zrikem
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Uniform Heat Flux ◽  
Coupled Heat Transfer ◽  
Uniform Heat ◽  
Alveolar Structure

Two-Dimensional Analysis of Conduction-Controlled Rewetting With Precursory Cooling

1976 ◽  
Vol 98 (3) ◽  
pp. 407-413 ◽  
Author(s):  
S. S. Dua ◽  
C. L. Tien
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Dimensional Analysis ◽  
Vertical Surface ◽  
Dimensionless Temperature ◽  
Two Dimensional ◽  
Dimensional Solution ◽  
One Dimensional ◽  
The One

This paper presents a two-dimensional analysis of the effect of precursory cooling on conduction-controlled rewetting of a vertical surface, whose initial temperature is higher than the sputtering temperature. Precursory cooling refers to the cooling caused by the droplet-vapor mixture in the region immediately ahead of the wet front, and is described mathematically by two dimensionless constants which characterize its magnitude and the region of influence. The physical model developed to account for precursory cooling consists of an infinitely extended vertical surface with the dry region ahead of the wet front characterized by an exponentially decaying heat flux and the wet region behind the moving film-front associated with a constant heat transfer coefficient. Apart from the two dimensionless constants describing the extent of precursory cooling, the physical problem is characterized by three dimensionless groups: the Peclet number or the dimensionless wetting velocity, the Biot number and a dimensionless temperature. Limiting solutions for large and small Peclet numbers have been obtained utilizing the Wiener-Hopf technique coupled with appropriate kernel substitutions. A semiempirical matching relation is then devised for the entire range of Peclet numbers. Existing experimental data with variable flow rates at atmospheric pressure are very closely correlated by the present model. Finally a comparison is drawn between the one-dimensional limit of the present analysis and the corresponding one-dimensional solution obtained by treating the dry region ahead of the wet front characterized by an exponentially decaying heat transfer coefficient.

The One-Dimensional Analysis of Oscillatory Heat Transfer in a Fin Assembly

1992 ◽  
Vol 114 (3) ◽  
pp. 548-552 ◽  
Author(s):  
J. M. Houghton ◽  
D. B. Ingham ◽  
P. J. Heggs
Keyword(s):  
Heat Transfer ◽  
Thermal Effects ◽  
Transient Heat Transfer ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Extended Surface ◽  
Extended Surfaces ◽  
The One ◽  
Physical Boundary ◽  
Surface Heat Exchanger

Studies of the transient heat transfer within extended surfaces have so far considered the fins in isolation. The isolated fin model is not representative of the physical boundary conditions within an extended surface heat exchanger since it does not account for the thermal effects of the supporting interface. The aim of this study is to extend the work on transient heat transfer within finned surfaces by incorporating the supporting wall in the problem. A mathematical one-dimensional solution for harmonic oscillatory heat transfer in a fin assembly is derived. It is concluded that, unlike steady-state situations, the transient heat transfer in a fin assembly can only be found by considering both the wall and the fins simultaneously.

Mechanisms of Coupled Heat Transfer and Flow of High Heat Flux Pulsating Heat Pipe

2004 ◽  
Author(s):  
Wei Qu ◽  
Yantao Qu ◽  
Tongze Ma
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Pipe ◽  
Latent Heat ◽  
High Heat ◽  
High Heat Flux ◽  
Sensible Heat ◽  
Pulsating Heat Pipe ◽  
Coupled Heat Transfer ◽  
Heating Section

The mechanisms of coupled heat transfer and flow are modeled to describe the looped pulsating heat pipe of high heat flux. The latent heat transfer produces the pressure difference between the heating section and cooling section. This can provide the operational driving force to overcome the total flow resistances. While the sensible heat transfer contributes more to the transferred power. The results demonstrate that the circulation flow velocity can balance the heat and mass transfers automatically. And the ratio of latent heat transfer to sensible heat transfer is within 30 percent.

THEORETICAL EVALUATION OF NEW PHASE DELAY METHODS FOR MEASURING LOCAL HEAT TRANSFER COEFFICIENTS

1999 ◽  
Vol 23 (3-4) ◽  
pp. 361-376 ◽  
Author(s):  
W. Turnbull ◽  
P. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Phase Delay ◽  
Driving Frequency ◽  
One Dimensional

A one-dimensional analytical solution has been derived for unsteady heat conduction within a semi infinite body, of high thermal resistance, that is subject to a surface heat flux that varies periodically with time. The heat flux is assumed to be generated within a thin isothermal coating. The model predicts that a phase delay will develop between the heat flux and the coating thermal response. This phase delay is independent upon the material properties of the substrate and coating, on the heat flux driving frequency, and on the local heat transfer, coefficient. With the exception of this last quantity the other parameters are known a priori, hence if the phase delay can be measured experimentally it can then be used to determine the local heat transfer coefficient. Absolute values of the local coating temperature and local heat flux are not required. Hence calibration of the devices for measuring these quantities should not be required. In contrast to the overall surface temperature, it is predicted that the phase delay angle will attain a steady-state value within a few heat flux cycles, thus reducing the time required obtaining a measurement. Furthermore, the one-dimensional mathematical model that has been developed reduces to those used in previous experimentally validated techniques, when appropriate constants in the boundary condition are used.

Impact of Above-Grade Walls on Three-Dimensional Building Foundation Heat Transfer From Slab-On Grade Floors

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Moncef Krarti
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Form Solution ◽  
Heat Losses ◽  
Dimensional Solution ◽  
Simplified Approach ◽  
Coupled Heat Transfer ◽  
Profile Estimation ◽  
The Impact

This paper presents a new three-dimensional analytical solution for transient ground-coupled heat transfer associated with slab-on-grade floor building foundations. The impact of above-grade walls on ground-coupled heat transfer is accounted for in the presented solution. The interzone temperature profile estimation (ITPE) technique is utilized to obtain the 3D solution suitable to determine soil temperature distributions and to estimate foundation heat loss/gain from slab-on-grade floors. The ITPE results are validated against results obtained from a closed-form solution in the case of steady-state conditions. It is found that that the above-grade walls can significantly affect the foundation heat losses especially for uninsulated slabs. Moreover, a simplified approach is proposed to obtain three-dimensional foundation heat losses from a two-dimensional solution.

Analytical Three-Dimensional Solution for Heat Sink Temperature

2004 ◽  
Author(s):  
Antti Lehtinen ◽  
Reijo Karvinen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Sink ◽  
Three Dimensional ◽  
Base Plate ◽  
Steady State Solution ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Dimensional Solution ◽  
Centerline Temperature

In the paper an analytical steady-state solution for heat transfer in a heat sink is presented. The heat sink consists of an array of fins and a base plate. The array is cooled by forced convection. There is a prescribed heat flux distribution at the bottom of the base plate. In order to obtain an analytical solution the assumption of a constant heat transfer coefficient is made. Furthermore, the array is assumed to be so short that the centerline temperature of the flow equals that of the free stream. The results are applied to a specific case of a single heat source, which generates constant heat flux and is mounted at the center of the bottom of the base plate. The use of the results is illustrated with a couple of simple numerical examples.

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