AN ENTROPY PRODUCTION METHOD TO INVESTIGATE THE ACCURACY AND STABILITY OF NUMERICAL SIMULATION OF ONE-DIMENSIONAL HEAT TRANSFER

2012 ◽  
Vol 43 (7) ◽  
pp. 669-693 ◽  
Author(s):  
Haochun Zhang ◽  
Y.-Y. Guo ◽  
Y. Jin ◽  
Y. Li
2017 ◽  
Vol 21 (suppl. 1) ◽  
pp. 97-104
Author(s):  
Ali Brohi ◽  
Haochun Zhang ◽  
Kossi Min-Dianey ◽  
Muhammad Rafique ◽  
Muhammad Hassan ◽  
...  

The entropy production in 2-D heat transfer system has been analyzed systematically by using the finite volume method, to develop new criteria for the numerical simulation in case of multidimensional systems, with the aid of the CFD codes. The steady-state heat conduction problem has been investigated for entropy production, and the entropy production profile has been calculated based upon the current approach. From results for 2-D heat conduction, it can be found that the stability of entropy production profile exhibits a better agreement with the exact solution accordingly, and the current approach is effective for measuring the accuracy and stability of numerical simulations for heat transfer problems.


2017 ◽  
Vol 743 ◽  
pp. 449-453
Author(s):  
Vladimir Arkhipov ◽  
Alexander Nee ◽  
Lily Valieva

This paper presents the results of mathematical modelling of three–dimensional heat transfer in a closed two-phase thermosyphon taking into account phase transitions. Three-dimensional conduction equation was solved by means of the finite difference method (FDM). Locally one-dimensional scheme of Samarskiy was used to approximate the differential equations. The effect of the thermosyphon height and temperature of its bottom lid on the temperature difference in the vapor section was shown.


Author(s):  
Dongliang Quan ◽  
Songling Liu ◽  
Jianghai Li ◽  
Gaowen Liu

Integrated impingement and pin fin cooling devices have comprehensive advantages of hot-side film cooling, internal impingement cooling, large internal heat transfer area and enhanced heat exchange caused by the pin fin arrays, so it is considered a promising cooling concept to meet the requirements of modern advanced aircraft engines. In this paper, experimental study, one dimensional model analysis and numerical simulation were conducted to investigate cooling performance of this kind of cooling device. A typical configuration specimen was made and tested in a large scale low speed closed-looped wind tunnel. The cooling effectiveness was measured by an infrared thermography technique. The target surface was coated carefully with a high quality black paint to keep a uniform high emissivity condition. The measurements were calibrated with thermocouples welded on the surface. Detailed two-dimensional contour maps of the temperature and cooling effectiveness were obtained for different pressure ratios and therefore different coolant flow-rates through the tested specimen. The experimental results showed that very high cooling effectiveness can be achieved by this cooling device with relatively small amount of coolant flow. Based on the theory of transpiration cooling in porous material, a one dimensional heat transfer model was established to analyze the effect of various parameters on the cooling effectiveness. The required resistance and internal heat transfer characteristics were obtained from experiments. It was found from this model that the variation of heat transfer on the gas side, including heat transfer coefficient and film cooling effectiveness, of the specimen created much more effect on its cooling effectiveness than that of the coolant side. The heat transfer intensities inside the specimen played an important role in the performance of cooling. In the last part of this paper, a conjugate numerical simulation was carried out using commercial software FLUENT 6.1. The domain of the numerical simulation included the specimen and the coolant. Detailed temperature contours of the specimen were obtained for various heat transfer boundary conditions. The calculated flow resistance and cooling effectiveness agree well with the experimental data and the predictions with the one-dimensional analysis model. The numerical simulations reveal that the impingement of the coolant jets in the specimen is the main contribution to the high cooling effectiveness.


2020 ◽  
Vol 37 (8) ◽  
pp. 2913-2938
Author(s):  
Rajul Garg ◽  
Harishchandra Thakur ◽  
Brajesh Tripathi

Purpose The study aims to highlight the behaviour of one-dimensional and two-dimensional fin models under the natural room conditions, considering the different values of dimensionless Biot number (Bi). The effect of convection and radiation on the heat transfer process has also been demonstrated using the meshless local Petrov–Galerkin (MLPG) approach. Design/methodology/approach It is true that MLPG method is time-consuming and expensive in terms of man-hours, as it is in the developing stage, but with the advent of computationally fast new-generation computers, there is a big possibility of the development of MLPG software, which will not only reduce the computational time and cost but also enhance the accuracy and precision in the results. Bi values of 0.01 and 0.10 have been taken for the experimental investigation of one-dimensional and two-dimensional rectangular fin models. The numerical simulation results obtained by the analytical method, benchmark numerical method and the MLPG method for both the models have been compared with that of the experimental investigation results for validation and found to be in good agreement. Performance of the fin has also been demonstrated. Findings The experimental and numerical investigations have been conducted for one-dimensional and two-dimensional linear and nonlinear fin models of rectangular shape. MLPG is used as a potential numerical method. Effect of radiation is also, implemented successfully. Results are found to be in good agreement with analytical solution, when one-dimensional steady problem is solved; however, two-dimensional results obtained by the MLPG method are compared with that of the finite element method and found that the proposed method is as accurate as the established method. It is also found that for higher Bi, the one-dimensional model is not appropriate, as it does not demonstrate the appreciated error; hence, a two-dimensional model is required to predict the performance of a fin. Radiative fin illustrates more heat transfer than the pure convective fin. The performance parameters show that as the Bi increases, the performance of fin decreases because of high thermal resistance. Research limitations/implications Though, best of the efforts have been put to showcase the behaviour of one-dimensional and two-dimensional fins under nonlinear conditions, at different Bi values, yet lot more is to be demonstrated. Nonlinearity, in the present paper, is exhibited by using the thermal and material properties as the function of temperature, but can be further demonstrated with their dependency on the area. Additionally, this paper can be made more elaborative by extending the research for transient problems, with different fin profiles. Natural convection model is adopted in the present study but it can also be studied by using forced convection model. Practical implications Fins are the most commonly used medium to enhance heat transfer from a hot primary surface. Heat transfer in its natural condition is nonlinear and hence been demonstrated. The outcome is practically viable, as it is applicable at large to the broad areas like automobile, aerospace and electronic and electrical devices. Originality/value As per the literature survey, lot of work has been done on fins using different numerical methods; but to the best of authors’ knowledge, this study is first in the area of nonlinear heat transfer of fins using dimensionless Bi by the truly meshfree MLPG method.


2019 ◽  
Vol 36 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Feng Cheng ◽  
Shuo Tang ◽  
Dong Zhang ◽  
Yi Li

Abstract The quasi-one-dimensional method for the dual-mode scramjet (DMR) of the hypersonic RBCC powered vehicle was simplified in most of open researches. Furthermore, these simplified method can not fully capture the processes of wall heat transfer, changes in the boundary layer and the ratio of specific heat and the transonic flow in the reacting flow. Addressing this problem, we establish the models for processing core flow area, transonic flow and pre-combustion shock train (PCST) based on the governing equations for quasi-one-dimensional flow and certain assumptions. Thus the quasi-one-dimensional model of dual-mode scramjet engine that incorporates the changes in wall heat transfer and in the ratio of specific heat is built. Then, the reliability and accuracy of the model are assessed qualitatively and quantitatively by experiment and CFD numerical simulation. There is a high agreement between the theoretical calculations and the results of experimental data and CFD numerical simulation. This work expands the application scope and increases the reliability of quasi-one-dimensional model of dual-mode scramjet engine in RBCC engine. The results shed new light on the preliminary performance assessment and engineering application of dual-mode scramjet engine.


Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 601
Author(s):  
Saurabh Yadav ◽  
Jie Liu ◽  
Man Sik Kong ◽  
Young Gyoon Yoon ◽  
Sung Chul Kim

In this study, experiments were performed to use the waste heat in a billet casting industry utilizing bismuth telluride thermoelectric generators (TEGs). Four d-type absorber plates made of copper were installed above the manufactured billet during the cooling process. Three sides of each absorber plate were attached to thermoelectric units. Therefore, a total of 12 units of the thermoelectric system were found to generate a power of 339 W. The power density of the TEG system was found to be 981 W/m2 while running the system at the operating voltage of the battery energy storage system (58 V). A one-dimensional numerical simulation was carried out using FloMASTERTM v9.1 (Mentor Graphics Corporation, Siemens, Dallas, TX, USA) to verify the experimental results, and the numerical results were found to exhibit good agreement with the experimental results. Furthermore, a one-dimensional numerical simulation was carried out to obtain the heat transfer characteristics at varying flow rates of cold water (Reynolds number = 2540–16,943) and at different inlet temperatures (10–25 °C) for the cold side of the TEG. The results indicate that the performance of the thermoelectric generator increases with an increase in the cold-water flow rate and a decrease in the inlet temperature of the cold water.


2011 ◽  
Vol 228-229 ◽  
pp. 416-421
Author(s):  
Zhi Ming Zhou ◽  
Wei Jiu Huang ◽  
M. Deng ◽  
Min Min Cao ◽  
Li Wen Tang ◽  
...  

The numerical simulation model of single roller rapid solidification melt-spinning CuFe10 alloys was built in this paper. The vacuum chamber, cooling roller and sample were taken into account as a holistic heat system. Based on the heat transfer theory and liquid solidification theory, the heat transfer during the rapids solidification process of CuFe10 ribbons prepared by melt spinning can be approximately modeled by one-dimensional heat conduction equation, so that the temperature distribution and the cooling rate of the ribbon can be determined by the integration of this equation. The simulative results are coincident very well with the microstructure of rapid solidification melt spinnng CuFe10 alloys at three different wheel speeds 4, 12 and 36 m/s.


2011 ◽  
Vol 189-193 ◽  
pp. 3949-3953
Author(s):  
Zhi Ming Zhou ◽  
Bin Bin Lei ◽  
Li Wen Tang ◽  
Tao Zhou ◽  
Yang Hu ◽  
...  

The numerical simulation model of rapid solidification splat-quenching CuCr25 alloys was built in this paper. The vacuum chamber, cooling cooper plate and sample were taken into account as a holistic heat system. Based on the heat transfer theory and liquid solidification theory, the heat transfer during the rapids solidification process of CuCr25 flakes prepared by splat-quenching can be approximately modeled by one-dimensional heat conduction equation, so that the temperature distribution and the cooling rate of the flake can be determined by the integration of this equation. The simulative results are coincident very well with the experimental results for the microstructure of rapid solidification splat-quenched CuCr25 alloys.


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