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Hassan Hajabdollahi - One of the best experts on this subject based on the ideXlab platform.
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Rotary Regenerator: Constructal thermoeconomic optimization
Journal of the Taiwan Institute of Chemical Engineers, 2020Co-Authors: Hassan Hajabdollahi, Mohammad Shafiey DehajAbstract:Abstract In this research, Rotary Regenerator (RR) is optimized using constructal theory. For this aim, a heat exchanger with two branches is considered. RR effectiveness and total annual cost (TAC) are deliberated as objective functions and 9 design variables are selected. The multi-objective optimization algorithm is used to obtain the optimal values of objective functions and design variables. The optimum results in the case of constructal are contrasted with optimum results in the conventional RR. The optimum results showed better thermoeconomic results in the case of constructal than conventional RR for the effectiveness higher than 0.6572. As an example, effectiveness improved by 6.98% in the case of constructal in comparison to conventional RR for the constant value of TAC=1821$/year. In addition, the optimum results showed 4.55% improvement in the maximum effectiveness in constructal compared with conventional RR. Finally, distribution of design parameters along with some important parameters such as heat transfer surface area and pressure drop for both studied cases are illustrated, compared and discussed.
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Comparison of stationary and Rotary matrix heat exchangers using teaching-learning-based optimization algorithm:
Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2017Co-Authors: Hassan HajabdollahiAbstract:In this paper, two kinds of compact heat exchanger including plate fin heat exchanger and Rotary Regenerator, respectively the stationary and Rotary matrix heat exchanger, are compared. For this purpose, both heat exchangers are optimized by considering three simultaneous objective functions including effectiveness, heat exchanger volume, and total pressure drop using multi-objective teaching learning based optimization algorithm. Six different design parameters are considered for the both plate fin heat exchanger and Rotary Regenerator. Optimization is performed for the same and different hot and cold side mass flow rates. The optimum results reveal 13.26% growth in the effectiveness, 475.17% increase in the volume, and 95.45% reduction in the pressure drop in RR as compared with plate fin heat exchanger and for the final optimum point. As a result, Rotary Regenerator is more suitable in the case of high effectiveness and low pressure drop while plate fin heat exchanger is more suitable in the case of sp...
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Multi-objective optimization of Rotary Regenerator using genetic algorithm
International Journal of Thermal Sciences, 2009Co-Authors: Sepehr Sanaye, Hassan HajabdollahiAbstract:Abstract The Rotary Regenerator (heat wheel) is an important heat recovery equipment, which rotates between two cold and hot streams. The pressure drop and effectiveness of Rotary Regenerator are important parameters in optimal design of this equipment for industrial applications. For optimal design of such a system, it was thermally modeled using ɛ-NTU method to estimate its pressure drop and effectiveness. Frontal area, ratio of hot to cold frontal heat transfer area, matrix thickness, matrix rotational speed, matrix rod diameter and porosity were considered as design parameters. Then fast and elitist non-dominated sorting genetic algorithm (NSGA-II) method was applied to find the optimum values of design parameters. In the presented optimal design approach, the effectiveness and the total pressure drop are two objective functions. The results of optimal designs were a set of multiple optimum solutions, called ‘Pareto optimal solutions’. The sensitivity analysis of change in optimum effectiveness and pressure drop with change in design parameters of the Regenerator was also performed and the results are reported.
Paulo Cesar Mioralli - One of the best experts on this subject based on the ideXlab platform.
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Heat transfer in a Rotary Regenerator with fixed pressure drop
2017Co-Authors: Paulo Cesar MioralliAbstract:Resumo: O processo de transferência de calor em um regenerador rotativo foi analisado a partir de valores estabelecidos para a perda de carga nos canais da matriz. A troca térmica no equipamento foi maximizada através da obtenção de um valor ótimo de porosidade para esta perda de carga fixada. Os dutos da matriz foram admitidos triangulares eqüiláteros. Um programa computacional foi confeccionado para a simulação do regenerador, no qual a velocidade dos fluidos e o coeficiente de transferência de calor foram obtidos através de correlações levando em consideração a região de entrada dos dutos. Estes resultados foram utilizados para a obtenção do calor transferido no regenerador através de uma resolução numérica. A influência do bloqueio parcial do escoamento nos canais da matriz, causado por parte da estrutura do equipamento, e os efeitos dos vazamentos sobre o calor transferido, devido às folgas de trabalho do regenerador, também foram investigados. Uma análise de escala foi efetuada e expressões para a estimativa da porosidade ótima e do calor máximo transferido no equipamento foram obtidas. Baseado nesta análise, parâmetros adimensionais foram introduzidos e foi verificado que a análise de escala é capaz de prever a ordem de grandeza da porosidade ótima e o correspondente calor máximo transferido. Por fim, uma formulação adimensional para o problema foi apresentada e a influência da rotação da matriz sobre o calor transferido no regenerador foi analisadaAbstract: Heat transfer from a Rotary Regenerator subject to constant pressure drop constraints was examined. The optimal porosity and the corresponding maximum heat transfer were obtained considering smooth and equilateral triangular matrix ducts. The fluid flow and the heat transfer coefficient were obtained from correlations taking into account the matrix ducts entrance region. These results were used as inputs to a numerical solution employed to evaluate the Regenerator thermal performance. The influence of flow partial blockage, caused by part of the equipment structure, and the effects of seal leakage on the heat transfer were also investigated. A scale analysis was conducted and equations to assess the optimal porosity and the maximum heat transfer were obtained. Based on this analysis, dimensionless parameters were introduced and it was verified that the scale analysis properly predicts the order of magnitude of the optimal porosity and the maximum heat transfer. Finally, a dimensionless formulation was suggested and the influence of matrix rotational speed was analyze
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Thermal analysis of a Rotary Regenerator with fixed pressure drop or fixed pumping power
Inglaterra, 2015Co-Authors: Paulo Cesar Mioralli, Marcelo Moreira GanzarolliAbstract:Heat transfer in a Rotary Regenerator subject to constant pressure drops or pumping power constraints was examined. The fluid flow and the convective heat transfer coefficient were determined from correlations. These results were used as inputs for a numerical solution which was applied to evaluate the Regenerator's thermal performance. A scale analysis was conducted to determine the order of magnitude of optimal porosity and maximum heat transfer. This analysis suggests the best scales to present heat transfer and heat capacity rate in dimensionless form. It was found that, for a given dimensionless pressure drop or pumping power, there is a level of porosity that maximizes the heat transfer rate. The scale analysis of power law predictions showed good agreement with numerical results. Diagrams are presented with curves of optimal operating conditions for the prescribed constraints for typical Rotary Regenerators with both streams under the laminar flow regime. (C) 2012 Elsevier Ltd. All rights reserved.52118719
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Thermal analysis of a Rotary Regenerator
2014Co-Authors: Paulo Cesar MioralliAbstract:Resumo: Este estudo concentra-se na análise térmica de um regenerador rotativo, no qual o processo de transferência de calor é investigado numericamente. As equações de transporte foram discretizadas utilizando o método de volumes finitos e um programa computacional em linguagem FORTRAN foi confeccionado para as simulações numéricas. Uma correlação para estimar o coeficiente médio de transferência de calor em um canal da matriz do regenerador foi obtida para o regime laminar de escoamento a partir da utilização do pacote numérico comercial PHOENICS 3.5. O valor de temperatura média de mistura na saída de cada escoamento foi obtido e comparado com o valor calculado por método existente em literatura. Os resultados foram analisados e também comparados com dados de campo e uma concordância relativamente boa foi observada. Através das simulações numéricas, foi possível obter a distribuição de temperatura ao longo de um canal do regenerador em diferentes posições angulares. Conhecendo essa distribuição de temperatura, é possível obter um dimensionamento adequado para o sistema de selagem acoplado na matriz do regenerador. Foi visto neste trabalho que o perfil de temperatura na direção axial é determinante no dimensionamento do sistema de selagem do regeneradorAbstract: This study focalizes on the thermal analysis of a Rotary Regenerator, in which the process of heat transfer is numerically investigated. The governing equations are solved using finite volume code. A computational code in FORTRAN programming language was made for the numerical simulations. A correlation for valuation the medium heat transfer coefficient in the duct, for flow in laminar regime, was obtained using a commercial code (PHOENICS 3.5). The value of mean temperature at the exit of each flow was obtained and compared with the value calculated by existent method in the literature. The results were analyzed and also compared with field data and a relatively good agreement was observed. Through the numerical simulations, it was possible to obtain the temperature distribution along a duct of the Regenerator in different angular position
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Thermal analysis of a Rotary Regenerator with fixed pressure drop or fixed pumping power
Applied Thermal Engineering, 2013Co-Authors: Paulo Cesar Mioralli, Marcelo Moreira GanzarolliAbstract:Abstract Heat transfer in a Rotary Regenerator subject to constant pressure drops or pumping power constraints was examined. The fluid flow and the convective heat transfer coefficient were determined from correlations. These results were used as inputs for a numerical solution which was applied to evaluate the Regenerator's thermal performance. A scale analysis was conducted to determine the order of magnitude of optimal porosity and maximum heat transfer. This analysis suggests the best scales to present heat transfer and heat capacity rate in dimensionless form. It was found that, for a given dimensionless pressure drop or pumping power, there is a level of porosity that maximizes the heat transfer rate. The scale analysis of power law predictions showed good agreement with numerical results. Diagrams are presented with curves of optimal operating conditions for the prescribed constraints for typical Rotary Regenerators with both streams under the laminar flow regime.
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Heat transfer in a Rotary Regenerator with fixed pressure drop
Universidade Estadual de Campinas . Faculdade de Engenharia Mecânica, 2009Co-Authors: Paulo Cesar MioralliAbstract:O processo de transferência de calor em um regenerador rotativo foi analisado a partir de valores estabelecidos para a perda de carga nos canais da matriz. A troca térmica no equipamento foi maximizada através da obtenção de um valor ótimo de porosidade para esta perda de carga fixada. Os dutos da matriz foram admitidos triangulares eqüiláteros. Um programa computacional foi confeccionado para a simulação do regenerador, no qual a velocidade dos fluidos e o coeficiente de transferência de calor foram obtidos através de correlações levando em consideração a região de entrada dos dutos. Estes resultados foram utilizados para a obtenção do calor transferido no regenerador através de uma resolução numérica. A influência do bloqueio parcial do escoamento nos canais da matriz, causado por parte da estrutura do equipamento, e os efeitos dos vazamentos sobre o calor transferido, devido às folgas de trabalho do regenerador, também foram investigados. Uma análise de escala foi efetuada e expressões para a estimativa da porosidade ótima e do calor máximo transferido no equipamento foram obtidas. Baseado nesta análise, parâmetros adimensionais foram introduzidos e foi verificado que a análise de escala é capaz de prever a ordem de grandeza da porosidade ótima e o correspondente calor máximo transferido. Por fim, uma formulação adimensional para o problema foi apresentada e a influência da rotação da matriz sobre o calor transferido no regenerador foi analisadaHeat transfer from a Rotary Regenerator subject to constant pressure drop constraints was examined. The optimal porosity and the corresponding maximum heat transfer were obtained considering smooth and equilateral triangular matrix ducts. The fluid flow and the heat transfer coefficient were obtained from correlations taking into account the matrix ducts entrance region. These results were used as inputs to a numerical solution employed to evaluate the Regenerator thermal performance. The influence of flow partial blockage, caused by part of the equipment structure, and the effects of seal leakage on the heat transfer were also investigated. A scale analysis was conducted and equations to assess the optimal porosity and the maximum heat transfer were obtained. Based on this analysis, dimensionless parameters were introduced and it was verified that the scale analysis properly predicts the order of magnitude of the optimal porosity and the maximum heat transfer. Finally, a dimensionless formulation was suggested and the influence of matrix rotational speed was analyze
Teodor Skiepko - One of the best experts on this subject based on the ideXlab platform.
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a comparison of Rotary Regenerator theory and experimental results for an air preheater for a thermal power plant
Experimental Thermal and Fluid Science, 2004Co-Authors: Teodor Skiepko, R K ShahAbstract:Abstract The aim of the paper is to compare results obtained based on theoretical modeling with directly measured experimental data on a full scale operating air preheater. First, the model of Rotary Regenerator energy transport involving longitudinal matrix heat conduction is formulated in the paper. Then a solution of the model equation system is presented with reference to authors’ former papers. The results representing temperature distributions of heat exchanging gases and continuously rotating matrix are illustrated by means of 3D charts. For the Rotary air preheater of 5.3 m diameter, the temperature distributions computed are compared with experimental data. Right trends and a fair agreement between theory and experiments are found. Finally, the computed and experimental Regenerator heat transfer effectivenesses are compared and found to be within ±3% agreement at about 88% Regenerator effectiveness.
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Influence of leakage distribution on the thermal performance of a Rotary Regenerator
Applied Thermal Engineering, 1999Co-Authors: R K Shah, Teodor SkiepkoAbstract:A comprehensive modeling is proposed for leakages and thermal performance of Rotary Regenerators in this paper. It represents a substantial refinement over that available in the literature. Two separate models are proposed for the energy transfer in the Regenerator. The first refers to the heat transfer and pressure drop process. The second, based on a gas flow network, represents modeling of leakage distribution within the Regenerator. The solution to both models is obtained iteratively with proper input data and yields the thermal/flow design parameters of a Rotary Regenerator. These models use experimental correlations describing the Nusselt number, friction factor and seal discharge coefficients. A design procedure is outlined for the rating problem and details are referenced. Keeping the pressure leakage factor constant, the rating problem has been solved for different distributions of leakages through radial, peripheral and axial seals. The results clearly demonstrate that a significant reduction could occur in the thermal energy transfer to the cold fluid even with reasonably small (5% or so) individual leakages.
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Indirect Estimation of Leakage Distribution in Steam Boiler Rotary Regenerators
Heat Transfer Engineering, 1997Co-Authors: Teodor SkiepkoAbstract:Leakages are inherently associated with the heat transfer process in a Rotary heat exchanger, owing to clearances brought about by construction difficulties and rotor-housing thermal distortions. The method proposed permits one to evaluate leakage distributions within steam boiler Rotary Regenerators. In principle, the method is based on a gas flow diagram of the Regenerator, where gas streams are arranged into a network in which the corresponding mass flow rates are governed by pressure drops in the seals and matrix rotation. Moreover, energy and mass balances are taken into account where appropriate. On this basis, a nonlinear equation system modeling gas flows within the Rotary Regenerator is derived. Supplementing this system with data determined experimentally, one obtains a closed form of the gas flow problem, the solution of which gives particular gas mass flow rates within the Regenerator and the leakage distribution resulting from it. On the basis of experiments carried out on real devices, the a...
Vivek Patel - One of the best experts on this subject based on the ideXlab platform.
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Thermal Design and Optimization of Heat Exchangers
Thermal System Optimization, 2019Co-Authors: Vivek Patel, Vimal Savsani, Mohamed A. TawhidAbstract:Heat exchangers are energy conservation equipment used to transfer heat between hot and cold fluid. In this chapter, thermal modeling of different types of heat exchangers like shell and tube heat exchanger, plate-fin heat exchanger, fin and tube heat exchanger, plate heat exchanger, and Rotary Regenerator is presented. The objective function for each of the heat exchanger is derived from the thermal model. Optimization of a derived objective is performed by implementing 11 different metaheuristic algorithms for each heat exchanger, and comparative results are tabulated and discussed.
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Multi-objective optimization of a Rotary Regenerator using tutorial training and self-learning inspired teaching-learning based optimization algorithm (TS-TLBO)
Applied Thermal Engineering, 2016Co-Authors: Bansi D. Raja, R.l. Jhala, Vivek PatelAbstract:Abstract In the present work, tutorial training and self-learning inspired teaching-learning-based optimization (TS-TLBO) algorithm is proposed and investigated for the multi-objective optimization of a Rotary Regenerator. Two conflicting objectives, namely Regenerator effectiveness and total pressure drop, are considered simultaneously for the multi-objective optimization. Six design variables such as frontal area, matrix rod diameter, matrix thickness, matrix rotation speed, split and porosity are considered for optimization. Application examples are presented to demonstrate the effectiveness and accuracy of the proposed algorithm. The results of optimal designs are presented in a set of multiple optimum solutions, called Pareto-optimal solutions. Moreover, to reveal the level of conflict between these two objectives, the distribution of each design variables in their allowable range is also shown in two-dimensional objective spaces. Furthermore, the effect of change in the value of design variables on the objective function value is also performed in detail. Looking at the different design points of Pareto front, 99.4% reduction in total pressure drop is observed at the cost of 97.9% reduction in Regenerator effectiveness. Also, the matrix rod thickness, split and porosity were found to be important design variables that caused a strong conflict between the objective functions.
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Design optimization of Rotary Regenerator using artificial bee colony algorithm
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2011Co-Authors: R V Rao, Vivek PatelAbstract:This study explores the use of artificial bee colony (ABC) algorithm for the design optimization of Rotary Regenerator. Maximization of Regenerator effectiveness and minimization of Regenerator pressure drop are considered as objective functions and are treated individually and then simultaneously for single-objective and multi-objective optimization, respectively. Seven design variables such as Regenerator frontal area, matrix rotational speed, matrix rod diameter, matrix thickness, porosity, and split are considered for optimization. A case study is also presented to demonstrate the effectiveness and accuracy of the proposed algorithm. The results of optimization using ABC algorithm are validated by comparing with those obtained using genetic algorithm for the same case study. The effect of variation of ABC algorithm parameters on convergence and fitness value of the objective function has also been presented.
Yiwu Weng - One of the best experts on this subject based on the ideXlab platform.
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Numerical Investigations of the Influencing Factors on a Rotary Regenerator-Type Catalytic Combustion Reactor
Catalysts, 2018Co-Authors: Zhenkun Sang, Yiwu WengAbstract:Ultra-low calorific value gas (ULCVG) not only poses a problem for environmental pollution, but also createsa waste of energy resources if not utilized. A novel reactor, a Rotary Regenerator-type catalytic combustion reactor (RRCCR), which integrates the functions of a Regenerator and combustor into one component, is proposed for the elimination and utilization of ULCVG. Compared to reversal-flow reactor, the operation of the RRCCR is achieved by incremental rotation rather than by valve control, and it has many outstanding characteristics, such as a compact structure, flexible application, and limited energy for circulation. Due to the effects of the variation of the gas flow and concentration on the performance of the reactor, different inlet velocities and concentrations are analyzed by numerical investigations. The results reveal that the two factors have a major impact on the performance of the reactor. The performance of the reactor is more sensitive to the increase of velocity and the decrease of methane concentration. When the inlet concentration (2%vol.) is reduced by 50%, to maintain the methane conversion over 90%, the inlet velocity can be reduced by more than three times. Finally, the highly-efficient and stable operating envelope of the reactor is drawn.
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Investigation of Catalytic Combustion in the Rotary Regenerator Type Catalytic Combustor at Different Inlet Velocities
Volume 2: I&C Digital Controls and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations Maintenance Agi, 2017Co-Authors: Zhenkun Sang, Xiaojing Lv, Zemin Bo, Yiwu WengAbstract:Ultra low calorific value gas (ULCVG) is hard to be realized by the conventional combustion technology. Most of them are discarded into atmosphere directly, causing the inadvertent waste and serous pollution. Currently, a new type gas turbine with catalytic combustion and Rotary Regenerator can be used to utilize these fuels and mitigate pollution. Differing from the conventional gas turbine, the chamber and Regenerator of the new gas turbine is combined into one component, which is named Rotary recuperative type catalytic chamber (RRTCC). The catalytic combustion is applied for RRTCC. The catalytic combustion characteristic of RRTCC is studied using the computational fluid dynamics (CFD). The results indicate that when the inlet velocity is 20 m/s, the methane conversion rate is 90%∼95%, and the corresponding outlet gas temperature is 1030∼1200K. When there is a variation of ±25% in the inlet velocity, the variation of methane conversation rate is −15% and 5% respectively, and the variation of outlet gas temperature is −6% and 2% respectively. Additionally, it is found that the hotspot temperature of combustor wall decreases with the increase of inlet velocity. The lowest value of hotspot temperature is about 1000K, which is higher than the ignition temperature of CH4. Therefore, the existence of hotspot temperature is useful for the catalytic ignition. The temperature distribution on the combustion side exhibits a smoking-pipe-like shape, as well as the recuperative side. The results can provide data reference for RRTCC design.
