Analysis of Heat Transfer by Natural Convection Across Vertical Fluid Layers

1977 ◽  
Vol 99 (2) ◽  
pp. 287-293 ◽  
Author(s):  
G. D. Raithby ◽  
K. G. T. Hollands ◽  
T. E. Unny
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Average Nusselt Number ◽  
Vertical Temperature ◽  
The Core ◽  
Aspect Ratios ◽  
Fluid Layers ◽  
Transfer Equations ◽  
Vertical Temperature Distribution ◽  
Good Agreement

An analysis is presented which predicts the heat transfer across fluid layers bounded laterally by vertical isothermal surface and adiabatic surfaces on the top and bottom. The vertical temperature distribution in the core of the cavity is also predicted. Extensive comparisons of average Nusselt number and temperature distribution are made with experimental data for aspect ratios greater than 5. Good agreement between analysis and experiment is found. The heat-transfer equations for vertical layers are generalized to include layers which are tilted up to 20° from the vertical, making the results useful for the design of solar collectors.

Optimal Perturbation Iteration Method for Solving Nonlinear Heat Transfer Equations

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Sinan Deniz
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Iteration Method ◽  
Numerical Solutions ◽  
Nonlinear Differential Equations ◽  
Optimal Perturbation ◽  
Transfer Equations ◽  
Better Than ◽  
Good Agreement ◽  
Distribution Equation

In this paper, the new optimal perturbation iteration method (OPIM) is introduced and applied for solving nonlinear differential equations arising in heat transfer. The effectiveness of the proposed method will be tested by considering two specific applications: the temperature distribution equation in a thick rectangular fin radiation to free space and cooling of a lumped system with variable specific heat. Comparing different methods shows that the results obtained by optimal perturbation iteration method are very good agreement with the numerical solutions and perform better than the most existing analytic methods.

Prediction of the Vertical Temperature Distribution in a Large Enclosure Under Combined Air Conditioning and Natural Ventilation

Solar Energy ◽  
2004 ◽  
Author(s):  
Jun Gao ◽  
Xiao-Dong Li ◽  
Jia-Ning Zhao ◽  
Fu-Sheng Gao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Air Temperature ◽  
Air Conditioning ◽  
Natural Ventilation ◽  
Vertical Temperature ◽  
Combined System ◽  
Efficient System ◽  
Macro Scale ◽  
Vertical Temperature Distribution

This paper describes a combined system of air conditioning and natural ventilation for large enclosures. A multi-zonal model to simulate the vertical temperature distribution is established. This model describes airflow and heat transfer on a ‘macro’ scale compared to CFD model, but it appears very efficient for engineering application. In this model, air density is considered to change with air temperature. Multiple air jets, buoyancy driven natural ventilation and coupled heat transfer are taken into consideration. It is governed by non-linear equations and is resolved by an iterative solution. A program is compiled to calculate the mass flow and temperature distributions. It shows that the combined system of air conditioning and natural ventilation cut considerably down heat gain in occupied zone. By comparison, the combined system can be expected to give lower temperature both in the enclosure and on interior surfaces. Some cases are calculated, and the results suggest that it depends on many factors such as the height of ventilating opening, the effective opening area, and outdoor air temperature to effectively make use of natural ventilation in the combined system. To sum up, this paper presents an energy efficient system for large spaces and also a theoretical model to design the system and predict the vertical temperature distribution.

scholarly journals TWO APPROACHES TO THE COMPUTATION OF ELECTROTHERMAL PROCESSES AT INDUCTION HEATING OF MOVING INGOTS – BY FIELD THEORY AND THERMAL CIRCUIT THEORY

2021 ◽  
Vol 2021 (59) ◽  
pp. 5-10
Author(s):  
A.A. Shcherba ◽  
◽  
A.D. Podoltsev ◽  
I.M. Kucheriava ◽  
V.M. Zolotarev ◽  
...  
Keyword(s):  
Field Theory ◽  
Heat Transfer ◽  
Temperature Distribution ◽  
Induction Heating ◽  
Thermal Field ◽  
Circuit Theory ◽  
Thermal Processes ◽  
Computational Results ◽  
Thermal Circuit ◽  
Good Agreement

The model for the computation of thermal processes in induction heating installations with moving ingots is developed using equivalent thermal circuits. The controlled current sources as additional elements in the model are used to take into account the convective heat transfer along the moving ingot. The model is implemented in the program Matlab/Simulink and makes it possible to determine the temperature distribution along the ingot under steady-state heating conditions. The results are compared with data obtained by the alternative method which is based on the electromagnetic and thermal field theory and realized in the Comsol program. As shown the computational results by two methods concerning the temperature distribution along the ingot are in good agreement. The existing advantages and shortcomings of the used approaches are discussed. Ref. 8, fig. 3, table.

An experimental and non-dimensional study on the vertical temperature distribution of a sealed ship engine room fire

2018 ◽  
Vol 165 ◽  
pp. 22-33 ◽  
Author(s):  
Jinhui Wang ◽  
Yu Jiao ◽  
Long Shi ◽  
Qimiao Xie ◽  
Guoqiang Li ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Vertical Temperature ◽  
Engine Room ◽  
Vertical Temperature Distribution

Post-Test Investigations of BFBT Critical Power Tests With Trace

2009 ◽  
Author(s):  
Marc Thieme ◽  
Wolfgang Tietsch ◽  
Rafael Macian ◽  
Victor Hugo Sanchez Espinoza
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Critical Power ◽  
The Core ◽  
Fine Mesh ◽  
The Us ◽  
Post Test ◽  
Trace Model ◽  
Good Agreement ◽  
Transfer Models

The validation of heat transfer models of safety analysis codes such as TRACE is very important due to the strong interaction of the thermal hydraulics parameters with the core neutronics. TRACE is the reference system code of the US NRC for LWR. It is being developed and extensively validated within the international CAMP-program. In this paper, the validation of heat transfer models of TRACE related to the prediction of the critical power is presented. The validation is based on a large number of critical power tests performed in the NUPEC BFBT (BWR Full-Size Fine-Mesh Bundle Tests) facility in Japan. These tests were analysed with the TRACE Version 5 RC 2. The comparison of predictions with the experimental data shows good agreement. The developed TRACE model and the comparison of experimental data with code results will be presented and discussed.

scholarly journals VI. The vertical temperature distribution the atmosphere over England, and some remarks on the general and local circulation

1912 ◽  
Vol 211 (471-483) ◽  
pp. 253-278 ◽  
Keyword(s):  
Temperature Distribution ◽  
British Isles ◽  
Vertical Temperature ◽  
Local Circulation ◽  
The Past ◽  
Rubber Balloon ◽  
Vertical Temperature Distribution

During the past four years a considerable number of small free balloons carrying selfrecording instruments have been sent up in the British Isles, and sufficient observations have now accumulated to give some idea of the conditions which prevail over England, to a height of about 10 miles, in summer and winter, in cyclonic and anticyclonic weather. The method of obtaining observations is fully described in a publication of the Meteorological Office, M.O. 202. It will suffice here to state that a small selfrecording instrument, weighing 1 oz. (35 gr.), is attached by about 30 ft. (9 metres) of strong thread to a small rubber balloon. The balloon is 1 ft. diameter when unstretched. It is filled with hydrogen until it is expanded to about 1 m. diameter, securely tied up, and then let go. The balloons generally rise until they burst, and carry the instrument on the average to a height of 10 miles (16 km). A label offering a reward of 5 s . is attached to the instrument, and the reward is claimed and the instrument returned in two cases out of three.

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