Numerical Study of Transient and Steady-State Anisotropic Cylindrical Pin Fin Thermal Behavior

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Imane Aslib ◽  
Hamid Hamza ◽  
Nisrine Hanchi ◽  
Jawad Lahjomri ◽  
Abdelaziz Oubarra
Keyword(s):  
Heat Conduction ◽  
Steady State ◽  
Thermal Behavior ◽  
Temperature Profile ◽  
Numerical Study ◽  
Numerical Code ◽  
Transient Temperature ◽  
Physical Parameters ◽  
Pin Fin ◽  
Transient And Steady State

This paper deals with the transient thermal analysis of two-dimensional cylindrical anisotropic pin fin that contains tip convection and subjected to a prescribed temperature at the fin base. The heat conduction equation contains a dual second-order derivation, which precludes solving the equation by direct application of common exact methods. Therefore, an appropriate canonical mapping is selected as a solution to cancel the dual derivation of temperature in the mapped equations. The alternating-direction implicit finite difference method (ADI) performs the integration of the mapped equations in the novel space, which involve a complicate geometry. Applying the inverse spatial transformation provides transient temperature profile in the real geometry for full-field configuration. The established numerical code has been validated successfully with the analytical solutions of the usual fins (orthotropic and isotropic). The anisotropy effect is investigated by means of various contour plots of the temperature profile as well as heat transfer rate from the fin base and the effectiveness for different parameters of study (kr/kz, krz/kz , and  Bir) in transient and steady-state heat conduction. The numerical code allows the study of the thermal behavior of anisotropic, orthotropic, and isotropic cylindrical pin fin according to the geometrical and physical parameters, as well as the thermal conditions to which the pin fin is subjected. A parametric study is performed in view to compare the thermal behavior of the various pin fin kinds submitted to the same conditions.

Analysis of a Transient Asymmetrically Heated/Cooled Open Thermosyphon

1993 ◽  
Vol 115 (3) ◽  
pp. 621-630 ◽  
Author(s):  
G. F. Jones ◽  
J. Cai
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Vertical Plate ◽  
Numerical Study ◽  
Vertical Wall ◽  
Constant Heat Flux ◽  
Closed Form Expression ◽  
Transient Temperature ◽  
Large Reservoir ◽  
One Dimensional

We present a numerical study of transient natural convection in a rectangular open thermosyphon having asymmetric thermal boundary conditions. One vertical wall of the thermosyphon is either heated by constant heat flux (“warmup”) or cooled by convection to the surroundings (“cooldown”). The top of the thermosyphon is open to a large reservoir of fluid at constant temperature. The vorticity, energy, and stream-function equations are solved by finite differences on graded mesh. The ADI method and iteration with overrelaxation are used. We find that the thermosyphon performs quite differently during cooldown compared with warmup. In cooldown, flows are mainly confined to the thermosyphon with little momentum and heat exchange with the reservoir. For warmup, the circulation resembles that for a symmetrically heated thermosyphon where there is a large exchange with the reservoir. The difference is explained by the temperature distributions. For cooldown, the fluid becomes stratified and the resulting stability reduces motion. In contrast, the transient temperature for warmup does not become stratified but generally exhibits the behavior of a uniformly heated vertical plate. For cooldown and Ra > 104, time-dependent heat transfer is predicted by a closed-form expression for one-dimensional conduction, which shows that Nu → Bi1/2/A in the steady-state limit. For warmup, transient heat transfer behaves as one-dimensional conduction for early times and at steady state and for Ra* ≥ 105, can be approximated as that for a uniformly heated vertical plate.

scholarly journals Numerical Study Of Thermal Behavior Of Anisotropic Medium In Bidirectional Cylindrical Geometry

2019 ◽  
Vol 286 ◽  
pp. 08009
Author(s):  
Rabiâ Idmoussa ◽  
Nisrine Hanchi ◽  
Hamza Hamza ◽  
Jawad Lahjomri ◽  
Abdelaziz Oubarra
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Behavior ◽  
Anisotropic Medium ◽  
Numerical Study ◽  
Heat Conduction Problem ◽  
Inverse Transformation ◽  
Complicated Geometry ◽  
Alternating Directions Method ◽  
Transient Thermal

In this work, we investigate the transient thermal analysis of two-dimensional cylindrical anisotropic medium subjected to a prescribed temperature at the two end sections and to a heat flux over the whole lateral surface. Due to the complexity of analytically solving the anisotropic heat conduction equation, a numerical solution has been developed. It is based on a coordinate transformation that reduces the anisotropic cylinder heat conduction problem to an equivalent isotropic one, without complicating the boundary conditions but with a more complicated geometry. The equation of heat conduction for this virtual medium is solved by the alternating directions method. The inverse transformation makes it possible to determine the thermal behavior of the anisotropic medium as a function of study parameters: diagonal and cross thermal conductivities, heat flux.

scholarly journals A New Dynamic Model to Predict Transient and Steady State PV Temperatures Taking into Account the Environmental Conditions

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 2 ◽  
Author(s):  
Socrates Kaplanis ◽  
Eleni Kaplani
Keyword(s):  
Steady State ◽  
Environmental Conditions ◽  
Solar Irradiance ◽  
Model Performance ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Time Constants ◽  
Proposed Model ◽  
Pv Cell ◽  
Transient And Steady State

Photovoltaic (PV) cell and module temperature profiles, Tc and Tpv, respectively, developed under solar irradiance were predicted and measured both at transient and steady state conditions. The predicted and measured Tc or Tpv covered both a bare c-Si PV cell, by SOLARTEC, at laboratory conditions using a solar light simulator, as well as various c-Si and pc-Si modules (SM55, Bioenergy 195W, Energy Solutions 125W) operating in field conditions. The time constants, τ, of the Tc and Tpv profiles were determined by the proposed model and calculated using the experimentally obtained profiles for both the bare PV cell and PV modules. For model validation, the predicted steady state and transient temperature profiles were compared with experimental ones and also with those generated from other models. The effect of the ambient temperature, Ta, wind speed, vw, and the solar irradiance, IT, on the model performance, as well as of the mounting geometries, was investigated and incorporated in the prediction model. The predicted temperatures had the best matching to the measured ones in comparison to those from six other models. The model developed is applicable to any geographical site and environmental conditions.

Numerical Solution of Unsteady Conduction Heat Transfer in Anisotropic Cylinders

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Aslib Imane ◽  
Hamza Hamid ◽  
Lahjomri Jawad ◽  
Zniber Khalid ◽  
Oubarra Abdelaziz
Keyword(s):  
Heat Conduction ◽  
Steady State ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Heat Conduction Problem ◽  
Numerical Code ◽  
Inverse Transformation ◽  
Convective Boundary ◽  
Anisotropic Cylinder ◽  
Anisotropic Cylinders

This paper investigates a numerical solution of 2D transient heat conduction in an anisotropic cylinder, subjected to a prescribed temperature over the two end sections and a convective boundary condition over the whole lateral surface. The analysis of this anisotropic heat conduction problem is tedious because the corresponding partial differential equation contains a mixed-derivative. In order to overcome this difficulty, a linear coordinate transformation is used to reduce the anisotropic cylinder heat conduction problem to an equivalent isotropic one, without complicating the boundary conditions but with a more complicated geometry. The alternating-direction implicit finite-difference method (ADI) is used to integrate the isotropic equation combined with boundary conditions. Inverse transformation provides profile temperature in the anisotropic cylinder for full-field configuration. The numerical code is validated by the analytical heat conduction solutions available in the literature such as transient isotropic solution and steady-state orthotropic solution. The aim of this paper is to study the effect of cross-conductivity on the temperature profile inside an axisymmetrical anisotropic cylinder versus time, radial Biot number (Bir), and principal conductivities. The results show that cross-conductivity promotes the effect of Bir according to the principal conductivities. Furthermore, the anisotropy increases the time required to achieve the steady-state heat conduction.

The Effect of Room Temperature on the Generator’s Winding Coils Temperature

2014 ◽  
Vol 660 ◽  
pp. 783-787
Author(s):  
Y.N. Zaiazmin ◽  
K.A. Ismail ◽  
M.S. Abdul Manan ◽  
Atikah Haji Awang
Keyword(s):  
Steady State ◽  
Temperature Profile ◽  
Thermal Model ◽  
Room Temperature ◽  
Load Condition ◽  
Peak Temperature ◽  
Temperature Model ◽  
Confined Space ◽  
Steady State Model ◽  
Transient And Steady State

Thermal modeling is a method used to formulate a temperature profile for a generator. The most common types of thermal model used by researchers are transient and steady-state model. There is insufficient of information regarding prolong usage of a generator in a confined space. The purpose of this paper is to formulate an empirical temperature model for the winding coils for the duration of 24 hours and to investigate whether a peak temperature exists. From the results, it can be concluded that there is a peak temperature detected for the winding coils in a non-controlled room temperature that occurs after 9 hours of experiment. The effect of room temperature on the winding coils temperature for no load condition is only 6.6%.

Steady State Heat Conduction Modeling by the Generalized Finite Element Method

2018 ◽  
Author(s):  
Humberto Alves da Silveira Monteiro ◽  
Guilherme Garcia Botelho ◽  
Roque Luiz da Silva Pitangueira ◽  
Rodrigo Peixoto ◽  
FELICIO BARROS
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Heat Conduction ◽  
Steady State ◽  
Generalized Finite Element Method ◽  
State Heat ◽  
Steady State Heat ◽  
Generalized Finite Element ◽  
Element Method
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