Journal articles: 'Heat and mass transfer (incl. computational fluid dynamics)'

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Rojano, Fernando, Pierre-Emmanuel Bournet, Melynda Hassouna, Paul Robin, Murat Kacira, and Christopher Y. Choi. "Modelling heat and mass transfer of a broiler house using computational fluid dynamics." Biosystems Engineering 136 (August 2015): 25–38. http://dx.doi.org/10.1016/j.biosystemseng.2015.05.004.

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Wrobel, Luiz C., Maciej K. Ginalski, Andrzej J. Nowak, Derek B. Ingham, and Anna M. Fic. "An overview of recent applications of computational modelling in neonatology." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1920 (June 13, 2010): 2817–34. http://dx.doi.org/10.1098/rsta.2010.0052.

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This paper reviews some of our recent applications of computational fluid dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass-transfer mechanisms taking place in medical devices, such as incubators, radiant warmers and oxygen hoods. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and improving the design of medical devices.

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Qi, Ji, Jiafeng Lv, Zhen Li, Wei Bian, Jingfeng Li, and Shuqin Liu. "A Numerical Simulation of Membrane Distillation Treatment of Mine Drainage by Computational Fluid Dynamics." Water 12, no. 12 (December 3, 2020): 3403. http://dx.doi.org/10.3390/w12123403.

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Membrane distillation (MD) is a promising technology to treat mine water. This work aims to investigate the change in mass and heat transfer in reverse osmosis mine water treatment by vacuum membrane distillation (VMD). A 3D computational fluid dynamics (CFD) model was carried out using COMSOL Multiphysics and verified by the experimental results. Then, response Surface Methodology (RSM) was used to explore the effects of various parameters on the permeate flux and heat transfer efficiency. In terms of the influence degree on the permeation flux, the vacuum pressure > feed temperature > membrane length > feed temperature membrane length, and the membrane length has a negative correlation with the membrane flux. Increasing the feed temperature can also increase the convective heat transfer at the feed side, which will affect the heat transfer efficiency. Furthermore, the feed temperature also has a critical effect on the temperature polarization phenomenon. The temperature polarization becomes more notable at high temperatures.

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Khongprom, Parinya, Supawadee Ratchasombat, Waritnan Wanchan, Panut Bumphenkiattikul, and Sunun Limtrakul. "Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations." RSC Advances 10, no. 5 (2020): 2897–914. http://dx.doi.org/10.1039/c9ra10080f.

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Dixon, Anthony G., and Behnam Partopour. "Computational Fluid Dynamics for Fixed Bed Reactor Design." Annual Review of Chemical and Biomolecular Engineering 11, no. 1 (June 7, 2020): 109–30. http://dx.doi.org/10.1146/annurev-chembioeng-092319-075328.

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Flow, heat, and mass transfer in fixed beds of catalyst particles are complex phenomena and, when combined with catalytic reactions, are multiscale in both time and space; therefore, advanced computational techniques are being applied to fixed bed modeling to an ever-greater extent. The fast-growing literature on the use of computational fluid dynamics (CFD) in fixed bed design reflects the rapid development of this subfield of reactor modeling. We identify recent trends and research directions in which successful methodology has been established, for example, in computer generation of packings of complex particles, and where more work is needed, for example, in the meshing of nonsphere packings and the simulation of industrial-size packed tubes. Development of fixed bed reactor models, by either using CFD directly or obtaining insight, closures, and parameters for engineering models from simulations, will increase confidence in using these methods for design along with, or instead of, expensive pilot-scale experiments.

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Oon, C. S., A. Badarudin, S. N. Kazi, and M. Fadhli. "Simulation of Heat Transfer to Turbulent Nanofluid Flow in an Annular Passage." Advanced Materials Research 925 (April 2014): 625–29. http://dx.doi.org/10.4028/www.scientific.net/amr.925.625.

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The heat transfer in annular heat exchanger with titanium oxide of 1.0 volume % concentration as the medium of heat exchanger is considered in this study. The heat transfer simulation of the flow is performed by using Computational Fluid Dynamics package, Ansys Fluent. The heat transfer coefficients of water to titanium oxide nanofluid flowing in a horizontal counter-flow heat exchanger under turbulent flow conditions are investigated. The results show that the convective heat transfer coefficient of the nanofluid is slightly higher than that of the base fluid by several percents. The heat transfer coefficient increases with the increase of the mass flow rate of hot water and also the nanofluid.

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Sharma, Shubham, Shalab Sharma, Mandeep Singh, Parampreet Singh, Rasmeet Singh, Sthitapragyan Maharana, Nima Khalilpoor, and Alibek Issakhov. "Computational Fluid Dynamics Analysis of Flow Patterns, Pressure Drop, and Heat Transfer Coefficient in Staggered and Inline Shell-Tube Heat Exchangers." Mathematical Problems in Engineering 2021 (June 1, 2021): 1–10. http://dx.doi.org/10.1155/2021/6645128.

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In this numerical study, the heat transfer performance of shell-and-tube heat exchangers (STHXs) has been compared for two different tube arrangements. STHX having 21 and 24 tubes arranged in the inline and staggered grid has been considered for heat transfer analysis. Shell-and-tube heat exchanger with staggered grid arrangement has been observed to provide lesser thermal stratification as compared to the inline arrangement. Further, the study of variation in the mass flow rate of shell-side fluid having constant tube-side flow rate has been conducted for staggered grid structure STHX. The mass flow rate for the shell side has been varied from 0.1 kg/s to 0.5 kg/s, respectively, keeping the tube-side mass flow rate as constant at 0.25 kg/s. The influence of bulk mass-influx transfer rate on heat transfer efficiency, effectiveness, and pressure drop of shell-tube heat exchangers has been analyzed. CFD results were compared with analytical solutions, and it shows a good agreement between them. It has been observed that pressure drop is minimum for the flow rate of 0.1 kg/s, and outlet temperatures at the shell side and tube side have been predicted to be 40.94°C and 63.63°C, respectively.

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Wei, Xing, Bingbing Duan, Xuejun Zhang, Yang Zhao, Meng Yu, and Youming Zheng. "Numerical Simulation of Heat and Mass Transfer in Air-Water Direct Contact Using Computational Fluid Dynamics." Procedia Engineering 205 (2017): 2537–44. http://dx.doi.org/10.1016/j.proeng.2017.10.218.

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Chen, Long, and Binxin Wu. "Research Progress in Computational Fluid Dynamics Simulations of Membrane Distillation Processes: A Review." Membranes 11, no. 7 (July 7, 2021): 513. http://dx.doi.org/10.3390/membranes11070513.

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Membrane distillation (MD) can be used in drinking water treatment, such as seawater desalination, ultra-pure water production, chemical substances concentration, removal or recovery of volatile solutes in an aqueous solution, concentration of fruit juice or liquid food, and wastewater treatment. However, there is still much work to do to determine appropriate industrial implementation. MD processes refer to thermally driven transport of vapor through non-wetted porous hydrophobic membranes, which use the vapor pressure difference between the two sides of the membrane pores as the driving force. Recently, computational fluid dynamics (CFD) simulation has been widely used in MD process analysis, such as MD mechanism and characteristics analysis, membrane module development, preparing novel membranes, etc. A series of related research results have been achieved, including the solutions of temperature/concentration polarization and permeate flux enhancement. In this article, the research of CFD applications in MD progress is reviewed, including the applications of CFD in the mechanism and characteristics analysis of different MD structures, in the design and optimization of membrane modules, and in the preparation and characteristics analysis of novel membranes. The physical phenomena and geometric structures have been greatly simplified in most CFD simulations of MD processes, so there still is much work to do in this field in the future. A great deal of attention has been paid to the hydrodynamics and heat transfer in the channels of MD modules, as well as the optimization of these modules. However, the study of momentum transfer, heat, and mass transfer mechanisms in membrane pores is rarely involved. These projects should be combined with mass transfer, heat transfer and momentum transfer for more comprehensive and in-depth research. In most CFD simulations of MD processes, some physical phenomena, such as surface diffusion, which occur on the membrane surface and have an important guiding significance for the preparation of novel membranes to be further studied, are also ignored. As a result, although CFD simulation has been widely used in MD process modeling already, there are still some problems remaining, which should be studied in the future. It can be predicted that more complex mechanisms, such as permeable wall conditions, fouling dynamics, and multiple ionic component diffusion, will be included in the CFD modeling of MD processes. Furthermore, users’ developed routines for MD processes will also be incorporated into the existing commercial or open source CFD software packages.

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Ito, Kazuhide, Koki Mitsumune, Kazuki Kuga, Nguyen L. Phuong, Kenji Tani, and Kiao Inthavong. "Prediction of convective heat transfer coefficients for the upper respiratory tracts of rat, dog, monkey, and humans." Indoor and Built Environment 26, no. 6 (August 1, 2016): 828–40. http://dx.doi.org/10.1177/1420326x16662111.

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In vivo studies involving mammal surrogate models for toxicology studies have restrictions related to animal protection and ethics. Computer models, i.e., in silico models, have great potential to contribute towards essential understanding of heat and mass transfer phenomena in respiratory tracts in place of in vivo and in vitro studies. Here, we developed numerical upper airway models of a rat, a dog, a monkey, and two humans by using computed tomography data and then applied computational fluid dynamics analysis. Convective heat transfer coefficients were precisely analysed as a function of breathing airflow rate. Based on the computational fluid dynamics simulation results, the correlations between Nusselt ( Nu) number and the product of the Reynolds ( Re) and Prandtl ( Pr) numbers were summarized. The heat transfer efficiency (order of hc and correlation of Nu and RePr) in the upper airway of the dog seems to match those of the human models. On the other hand, the results for the rat and monkey showed clear differences compared with those of human models. The identified fundamental qualities of convective heat transfer phenomena in airways for rats, dogs, monkeys, and humans, have enabled discussions about quantitative differences of heat and mass transfer efficiency between different animals/species.

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Yeoh, Guan Heng, and Xiaobin Zhang. "Computational fluid dynamics and population balance modelling of nucleate boiling of cryogenic liquids: Theoretical developments." Journal of Computational Multiphase Flows 8, no. 4 (November 22, 2016): 178–200. http://dx.doi.org/10.1177/1757482x16674217.

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The main focus in the analysis of pool or flow boiling in saturated or subcooled conditions is the basic understanding of the phase change process through the heat transfer and wall heat flux partitioning at the heated wall and the two-phase bubble behaviours in the bulk liquid as they migrate away from the heated wall. This paper reviews the work in this rapid developing area with special reference to modelling nucleate boiling of cryogenic liquids in the context of computational fluid dynamics and associated theoretical developments. The partitioning of the wall heat flux at the heated wall into three components – single-phase convection, transient conduction and evaporation – remains the most popular mechanistic approach in predicting the heat transfer process during boiling. Nevertheless, the respective wall heat flux components generally require the determination of the active nucleation site density, bubble departure diameter and nucleation frequency, which are crucial to the proper prediction of the heat transfer process. Numerous empirical correlations presented in this paper have been developed to ascertain these three important parameters with some degree of success. Albeit the simplicity of empirical correlations, they remain applicable to only a narrow range of flow conditions. In order to extend the wall heat flux partitioning approach to a wider range of flow conditions, the fractal model proposed for the active nucleation site density, force balance model for bubble departing from the cavity and bubble lifting off from the heated wall and evaluation of nucleation frequency based on fundamental theory depict the many enhancements that can improve the mechanistic model predictions. The macroscopic consideration of the two-phase boiling in the bulk liquid via the two-fluid model represents the most effective continuum approach in predicting the volume fraction and velocity distributions of each phase. Nevertheless, the interfacial mass, momentum and energy exchange terms that appear in the transport equations generally require the determination of the Sauter mean diameter or interfacial area concentration, which strongly governs the fluid flow and heat transfer in the bulk liquid. In order to accommodate the dynamically changing bubble sizes that are prevalent in the bulk liquid, the mechanistic approach based on the population balance model allows the appropriate prediction of local distributions of Sauter mean diameter or interfacial area concentration, which in turn can improve the predictions of the interfacial mass, momentum and energy exchanges that occur across the interface between the phases. Need for further developments are discussed.

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Mtui, P. L. "Computational Fluid Dynamics Modeling of Palm Fruit Pyrolysis in a Fast Fluidized Bed Reactor." Advanced Materials Research 699 (May 2013): 822–28. http://dx.doi.org/10.4028/www.scientific.net/amr.699.822.

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The palm fruit biomass is introduced into the pyrolysis reactor bed and the transport equations for heat, mass and momentum transfer are solved using computational fluid dynamics (CFD) technique. The Eulerian-Eulerian approach is employed to model fluidizing behavior of the sand for an externally heated reactor prior to the introduction of the biomass. The particle motion in the reactor is computed using the drag laws which depend on the local volume fraction of each phase. Heat transfer from the fluidized bed to the biomass particles together with the pyrolysis reactions were simulated by Fluent CFD code through user-defined function (UDF). Spontaneous production of pyrolysis oil, char and non-condensable gases (NCG) confirm the observation widely reported in literature. The computer model can potentially be used to assess other candidate biomass sources also to assist design of optimized pyrolysis reactors.

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Khan, Sabuddin, H. C. Thakur, and Nazeem Khan. "A Computational Fluid Dynamic Study of Shell and Tube Heat Exchanger Using (CuO, Al₂O₃, TiO₂)-Water Nanofluids." Advanced Science, Engineering and Medicine 12, no. 12 (December 1, 2020): 1462–67. http://dx.doi.org/10.1166/asem.2020.2585.

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The Nusselt number for a Shell and tube Heat Exchanger with segmental baffles for different nanofluids, for different mass flow rate are discussed in the present paper. A shell and tube heat exchanger with 7 tubes and 4 segmental baffles modelling is done using SOLIDWORKS and simulation is done by the Computational Fluid Dynamic (CFD) software; ANSYS-FLUENT. By using Fluent, computational fluid dynamics software the heat transfer coefficient and various heat characteristics of Al2O3–H2O, TiO2–H2O and CuO–H2O for 1% volume of concentration nanofluids are estimated in the Shell and Tube Heat Exchanger considering the turbulent flow.

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Chen, Huajun, Yitung Chen, Hsuan-Tsung Hsieh, and Nathan Siegel. "Computational Fluid Dynamics Modeling of Gas-Particle Flow Within a Solid-Particle Solar Receiver." Journal of Solar Energy Engineering 129, no. 2 (August 25, 2006): 160–70. http://dx.doi.org/10.1115/1.2716418.

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A detailed three-dimensional computational fluid dynamics (CFD) analysis on gas-particle flow and heat transfer inside a solid-particle solar receiver, which utilizes free-falling particles for direct absorption of concentrated solar radiation, is presented. The two-way coupled Euler-Lagrange method is implemented and includes the exchange of heat and momentum between the gas phase and solid particles. A two-band discrete ordinate method is included to investigate radiation heat transfer within the particle cloud and between the cloud and the internal surfaces of the receiver. The direct illumination energy source that results from incident solar radiation was predicted by a solar load model using a solar ray-tracing algorithm. Two kinds of solid-particle receivers, each having a different exit condition for the solid particles, are modeled to evaluate the thermal performance of the receiver. Parametric studies, where the particle size and mass flow rate are varied, are made to determine the optimal operating conditions. The results also include detailed information for the gas velocity, temperature, particle solid volume fraction, particle outlet temperature, and cavity efficiency.

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Krawczyk, Piotr, and Krzysztof Badyda. "Two-dimensional CFD modeling of the heat and mass transfer process during sewage sludge drying in a solar dryer." Archives of Thermodynamics 32, no. 4 (December 1, 2011): 3–16. http://dx.doi.org/10.2478/v10173-011-0028-y.

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Two-dimensional CFD modeling of the heat and mass transfer process during sewage sludge drying in a solar dryer The paper presents key assumptions of the mathematical model which describes heat and mass transfer phenomena in a solar sewage drying process, as well as techniques used for solving this model with the Fluent computational fluid dynamics (CFD) software. Special attention was paid to implementation of boundary conditions on the sludge surface, which is a physical boundary between the gaseous phase - air, and solid phase - dried matter. Those conditions allow to model heat and mass transfer between the media during first and second drying stages. Selection of the computational geometry is also discussed - it is a fragment of the entire drying facility. Selected modelling results are presented in the final part of the paper.

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Onan, Cenk, Derya Burcu Ozkan, and Serkan Erdem. "CFD and Experimental Analysis of a Falling Film outside Smooth and Helically Grooved Tubes." Advances in Mechanical Engineering 6 (January 1, 2014): 915034. http://dx.doi.org/10.1155/2014/915034.

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Simultaneous heat and mass transfer are investigated in a falling film outside grooved and smooth tubes. A numerical analysis of the helically trapezoidal-grooved and reference smooth tube was performed in the computational fluid dynamics program “Ansys Fluent 14.” The three-dimensional model drawings in the x, y, and z coordinates are used, and the effects of the falling film outside the helically grooved tube on the surface temperature and surface heat transfer coefficient are determined. The average surface temperature, heat transfer coefficient, and Nu values are determined experimentally for a constant heat flux. An uncertainty analysis and Nu correlation for the grooved tube are also provided in this study. The Reynolds number varied between 50 and 350 for the falling film and between 1500 and 3500 for air. Using a computational fluid dynamics (CFD) analysis for the reference smooth tube, the experimental results are validated within 2–12% difference. The experimental results are also within 6–13% of the grooved tubes.

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Li, Yong An, Xue Lai Liu, Jia Jia Yan, and Teng Xing. "Research on Wet Thermal Recovery Plant Used by Air Conditioning." Advanced Materials Research 424-425 (January 2012): 1155–58. http://dx.doi.org/10.4028/www.scientific.net/amr.424-425.1155.

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Based on the simulation Computational Fluid Dynamics method, in view of air conditioning with wet thermal recovery plant for heat and mass transfer characteristic, establishes air channels in three-dimensional laminar flow and heat transfer, mass transfer coupling process of mathematical physics model, discusses the air conditioning with wet thermal recovery plant air channels in temperature, concentration and pressure parameters such as distribution, application enthalpy efficiency analysis method to the heat transfer performance is evaluated. The results indicate that structure parameters of wet thermal recovery plant used by air conditioning play important influence for the heat transfer performance and flow resistance performance. The research conclusion provides guidance for air conditioning with wet thermal recovery plant of optimization.

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Hayer, Hossein, Omid Bakhtiari, and Toraj Mohammadi. "Simulation of momentum, heat and mass transfer in direct contact membrane distillation: A computational fluid dynamics approach." Journal of Industrial and Engineering Chemistry 21 (January 2015): 1379–82. http://dx.doi.org/10.1016/j.jiec.2014.06.009.

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Wang, Zheng Tao, Wei Wei Liu, and Jing Jing Xu. "Numerical Simulation of Heat Transfer for the Ethyl Benzene Dehydrogenation Catalyst in the Kiln." Applied Mechanics and Materials 575 (June 2014): 672–76. http://dx.doi.org/10.4028/www.scientific.net/amm.575.672.

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In industrial reactors, the chemical or physical transformations are always expected to occur in the best way, so the performance controlling processes associated with mixing of reactants, heat transfer, contacting of multiple phases, mass transfer, chemical reactions, and phase changes are important. In this paper the heat transfer simulation of the gas-solid multiphase flow in ethylbenzene dehydrogenation catalyst kiln, heat conduction, convection and radiation involved, has been expressed by using the computational fluid dynamics (CFD) method. The present study can contribute to our better understanding of the heating process and at the same time, the thermal power distribution and temperature variation of the fluid and catalyst particles can provide guidance for the kiln design.

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Bošnjaković, Mladen, and Simon Muhič. "Numerical Analysis of Tube Heat Exchanger with Perforated Star-Shaped Fins." Fluids 5, no. 4 (December 13, 2020): 242. http://dx.doi.org/10.3390/fluids5040242.

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This article discusses the possibility of further reducing the mass of the heat exchanger with stainless steel star-shaped fins while achieving good heat transfer performance. For this purpose, we perforated the fins with holes Ø2, Ø3, and Ø4 mm. Applying computational fluid dynamics (CFD) numerical analysis, we determined the influence of each perforation on the characteristics of the flow field in the liquid–gas type of heat exchanger and the heat transfer for the range of Re numbers from 2300 to 16,000. With a reduction in the mass of the fins to 17.65% (by Ø4 mm), perforated fins had greater heat transfer from 5.5% to 11.3% than fins without perforation. A comparison of perforated star-shaped fins with annular fins was also performed. Perforated fins had 51.8% less mass than annular fins, with an increase in heat transfer up to 26.5% in terms of Nusselt number.

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Muthusamy, P., and Palanisamy Senthil Kumar. "Waste Heat Recovery Using Matrix Heat Exchanger from the Exhaust of an Automobile Engine for Heating Car’s Passenger Cabin." Advanced Materials Research 984-985 (July 2014): 1132–37. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.1132.

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The main objective of our work is to analysis the heat transfer rate for various fluids with different matrix heat exchanger (MHE) models and flow characteristic in matrix heat exchanger by using computational fluid dynamics (CFD) package with small car. The amount of heat carried by the cold fluid from hot fluid is mainly depends upon the mass flow rate of the working fluid. The heat transfer area per unit volume of tube is more. So, it increases the temperature of the cold fluid. Here, the hot and cold fluids are moving in the alternate tubes of heat exchanger in the counter flow direction. The small amounts of pressure drop are occurred but which is less compared to existing model. Flow disturbances are rectified in the MHE through the modifications made. Since, silicon carbide material is used as a polishing material to avoid the deposit of carbon at the inner side of the flow passage and this waste heat energy is used for heating passenger cabin during winter season. The wood is used as an insulating material to avoid the heat flow from fluid to atmosphere. Keywords-Heat transfer rate, Matrix heat exchanger, Working fluid, Polishing material.

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El Baamrani, Hayat, Lahcen Bammou, Ahmed Aharoune, and Abdallah Boukhris. "Volume of Fluid (VOF) Modeling of Liquid Film Evaporation in Mixed Convection Flow through a Vertical Channel." Mathematical Problems in Engineering 2021 (May 23, 2021): 1–12. http://dx.doi.org/10.1155/2021/9934593.

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In this paper, the volume of fluid (VOF) method in the OpenFOAM open-source computational fluid dynamics (CFD) package is used to investigate the coupled heat and mass transfer by mixed convection during the evaporation of water-thin film. The liquid film is falling down on the left wall of a vertical channel and is subjected to a uniform heat flux density, whereas the right wall is assumed to be insulated and dry. The gas mixture consists of air and water vapor. The governing equations in the liquid and in the gas areas with the boundary conditions are solved by using the finite volume method. The results which include temperature, velocity, and vapor mass fraction are presented. The effect of heat flux density, liquid inlet temperature, and mass flow rate on the heat and mass transfer are also analyzed. Better liquid film evaporation is noted for the system with a higher heat flux density and inlet liquid temperature or a lower mass flow rate. Therefore, the VOF method describes well the thermal and dynamic behavior during the evaporation of the liquid film.

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Ekaroek Phumnok, Waritnan Wanchan, Matinee Chuenjai, Panut Bumphenkiattikul, Sunun Limtrakul, Sukrittira Rattanawilai, and Parinya Khongprom. "Study of Hydrodynamics and Upscaling of Immiscible Fluid Stirred Tank using Computational Fluid Dynamics Simulation." CFD Letters 14, no. 6 (June 26, 2022): 115–33. http://dx.doi.org/10.37934/cfdl.14.6.115133.

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Stirred tanks are prevalent in various industries, including chemical, biochemical, and pharmaceutical industries. These reactors are suitable for ensuring efficient mass and heat transfer because adequate mixing can be achieved. Numerous studies have been conducted on small-scale stirred-tank reactors. However, upscaling such reactors is challenging because of the complex flow behavior inside the system, especially for the mixing of immiscible liquid–liquid systems. Thus, the objectives of this study were to examine the flow behavior and upscale an immiscible liquid–liquid stirred tank using CFD simulation by investigating a flat-bottomed stirred tank reactor, equipped with a six-blade Rushton turbine. The simulated results were in good agreement with those obtained experimentally. The scale of the reactor significantly affects the hydrodynamic behavior, and the uniformity of the radial distribution of the velocity decreases with increasing Reynolds number. Furthermore, the upscaling criteria were evaluated for geometric similarity and equal mixing times. The proposed scaling law reliably scaled up the immiscible liquid–liquid mixing in a stirred tank with a difference in the range of ±10%.

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Akter, Ferdusee, Ripa Muhury, Afroza Sultana, and Ujjwal Kumar Deb. "A Comprehensive Review of Mathematical Modeling for Drying Processes of Fruits and Vegetables." International Journal of Food Science 2022 (July 21, 2022): 1–10. http://dx.doi.org/10.1155/2022/6195257.

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Drying fruits and vegetables is a procedure of food preservation with simultaneous heat, mass, and momentum transfer, which increases the shelf life of the food product. The aim of this review was to provide an overview of the researches on mathematical modeling for drying of fruits and vegetables with the special emphasis on the computational approach. Various heat-mass transport models, their applications, and modern drying technologies to the food industry have been reported in this study. Computational fluid dynamics, a new approach for solving heat and mass transfer problems, increases the accuracy of the predicted values. To investigate the parameters of drying needs a significant amount of time as well as costly laboratory and experimental efforts. Therefore, computational modeling could be an effective alternative to experimental approaches. This review will be beneficial for future studies in drying processes, especially for modeling, analysis, design, and optimization of food science and food engineering.

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Hayer, Hossein, Omid Bakhtiari, and Toraj Mohammadi. "Analysis of heat and mass transfer in vacuum membrane distillation for water desalination using computational fluid dynamics (CFD)." Desalination and Water Treatment 55, no. 1 (July 29, 2014): 39–52. http://dx.doi.org/10.1080/19443994.2014.912158.

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Li, Chunming, Wei Wu, Yin Liu, Chenhui Hu, and Junjie Zhou. "Analysis of Air–Oil Flow and Heat Transfer inside a Grooved Rotating-Disk System." Processes 7, no. 9 (September 18, 2019): 632. http://dx.doi.org/10.3390/pr7090632.

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An investigation on the two-phase flow field inside a grooved rotating-disk system is presented by experiment and computational fluid dynamics numerical simulation. The grooved rotating-disk system consists of one stationary flat disk and one rotating grooved disk. A three-dimensional computational fluid dynamics model considering two-phase flow and heat transfer was utilized to simulate phase distributions and heat dissipation capability. Visualization tests were conducted to validate the flow patterns and the parametric effects on the flow field. The results indicate that the flow field of the grooved rotating-disk system was identified to be an air–oil flow. A stable interface between the continuous oil phase and the two-phase area could be formed and observed. The parametric analysis demonstrated that the inter moved outwards in the radial direction, and the average oil volume fraction over the whole flow field increased with smaller angular speed, more inlet mass flow of oil, or decreasing disk spacing. The local Nusselt number was remarkably affected by the oil volume fraction and the fluid flow speed distributions in this two-phase flow at different radial positions. Lastly, due to the change of phase volume fraction and fluid flow speed, the variation of the average Nusselt number over the whole flow field could be divided into three stages.

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Li, Yong An, Ting Ting Wang, Xue Lai Liu, and Teng Xing. "Thermal Performance Research of Thermal Recovery Unit for Air-Conditioning Systerm." Advanced Materials Research 243-249 (May 2011): 4965–68. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.4965.

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This document established a three-dimensional laminar mathematical and physical model which describes heat transfer, mass transfer coupling process in wet thermal recovery unit for air-conditioning systerms, based on Computational Fluid Dynamics (CFD) simulations. In addition, the research discussed the distributions of pressure, temperature, concentration and other parameters in the air channels. The heat transfer performance was analyzed by enthalpy efficiency. The results showed that the structural parameters of wet thermal recovery unit for air-conditioning systerm played important influence in the heat transfer performance and flow drag performance. The research set a foundation for the optimal design of wet thermal recovery unit for air-conditioning systerm.

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Raj, Ritu, and Vardan Singh Nayak. "Enhancement of Film Boiling Characteristics Using Computational Fluid Dynamics Analysis for Moving Steel Plate." SMART MOVES JOURNAL IJOSCIENCE 6, no. 2 (February 10, 2020): 33–42. http://dx.doi.org/10.24113/ijoscience.v6i2.271.

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Present study provides guidelines and recommendations for solving film boiling problems in steel plate production, where the surface temperature of steel plate is much higher than the saturation temperature of the liquid in contact with the plate surface and the entire steel plate surface is immersed in water. Due to the boiling mass exchange occurring at the vapor liquid interface bubbles of steam are periodically produced and emitted upward such a regime is known as film boiling. A computational fluid dynamics analysis of steel plate using VOF multiphase model moving at different velocity i.e. 0.1 to 0.5 m/sec. the volume of fraction for vapor phase have been obtained for different time interval, the generation of bubbles starts moving upwards after 0.05 sec, as time goes the formation of vapor bubbles generate and collapse more rapidly because the thermal boundary is very thin and the fluid temperature around the bubbles almost equal to the saturation temperature. The thermal properties of the steel plate are implicit to be constant with temperature for convenience because the present study is focused on the boiling heat transfer on the steel plate. The size of element is set as 0.1 mm to generate mesh and quad-4 rectangular elements used are which is a rectangular in shape with four nodes on each element are applied for the analysis. Results show that that the 37.98% of Convective heat transfer coefficient of mixture is increased and 13.1% of temperature drop has been observed with 40.67% of heat flux increased for the steel plate moving at 0.1 m/sec.

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Ozcan-Coban, Seda, Fatih Selimefendigil, Hakan Oztop, and Arif Hepbasli. "A review on computational fluid dynamics simulation methods for different convective drying applications." Thermal Science, no. 00 (2022): 70. http://dx.doi.org/10.2298/tsci220225070o.

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This paper focuses on the Computational Fluid Dynamics (CFD) studies on one of the commonly used drying processes for different applications. First, a brief information about drying is given with determining important properties that effect drying characteristics. Next, basic principles of CFD modelling are explained while capabilities of computational processing are presented. A detailed literature survey about CFD studies in convective drying process is then conducted. Finally, some sound concluding remarks are listed. It may be concluded that the CFD is a powerful and flexible tool that can be adopted to many different physical situations including complex scenarios, results of CFD simulations represent good predictions for fluid flow, heat and mass transfer of various drying methods and those numerical studies can be used for validation and controlling of applicability of new drying systems.

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Jurtz, Nico, Matthias Kraume, and Gregor D. Wehinger. "Advances in fixed-bed reactor modeling using particle-resolved computational fluid dynamics (CFD)." Reviews in Chemical Engineering 35, no. 2 (February 25, 2019): 139–90. http://dx.doi.org/10.1515/revce-2017-0059.

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Abstract In 2006, Dixon et al. published the comprehensive review article entitled “Packed tubular reactor modeling and catalyst design using computational fluid dynamics.” More than one decade later, many researchers have contributed to novel insights, as well as a deeper understanding of the topic. Likewise, complexity has grown and new issues have arisen, for example, by coupling microkinetics with computational fluid dynamics (CFD). In this review article, the latest advances are summarized in the field of modeling fixed-bed reactors with particle-resolved CFD, i.e. a geometric resolution of every pellet in the bed. The current challenges of the detailed modeling are described, i.e. packing generation, meshing, and solving with an emphasis on coupling microkinetics with CFD. Applications of this detailed approach are discussed, i.e. fluid dynamics and pressure drop, dispersion, heat and mass transfer, as well as heterogeneous catalytic systems. Finally, conclusions and future prospects are presented.

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Reddy Kukutla, Pol, and BVSSS Prasad. "Network analysis of a coolant flow performance for the combined impingement and film cooled first-stage of high pressure gas turbine nozzle guide vane." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 6 (April 16, 2018): 1977–89. http://dx.doi.org/10.1177/0954410018767290.

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The present paper describes a system-level thermo-fluid network analysis for the secondary air system analysis of a typically film-cooled nozzle guide vane with multiple actions of jet impingement. The one-dimensional simulation was done with the help of the commercially available Flownex 2015 software. The system-level thermo-fluid network results were validated with both the computational fluid dynamics results and experimentally available literature. The entire nozzle guide vane geometry was first mapped to a thermo-fluid network model and the pressure conditions at different nodes. The discharge and heat transfer coefficients obtained from the Ansys FLUENT were specified as inputs to the thermo-fluid network model. The results show that the one-dimensional simulation of the coolant mass flow rates and jet Nusselt number values are in good agreement with the three-dimensional computational fluid dynamics results.

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Grabowska, Karolina, Marcin Sosnowski, Jaroslaw Krzywanski, Karol Sztekler, Wojciech Kalawa, Anna Zylka, and Wojciech Nowak. "Analysis of heat transfer in a coated bed of an adsorption chiller." MATEC Web of Conferences 240 (2018): 01010. http://dx.doi.org/10.1051/matecconf/201824001010.

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Adsorption chillers can be a promising part of sustainable development concept of the global economy due to the utilization of low grade thermal energy sources for cooling production. Therefore, research aiming at improving their performance i.e. Coefficient of Performance (COP) by optimizing the heat and mass transfer condition in the adsorption beds are crucial. Innovative modification of the sorbent layer structure are proposed in the paper in order to improve the heat transfer characteristics in the heat exchanger boundary layer. The analysis of desorption conditions in the parametric model of a coated adsorption bed construction is presented in the paper. The computational fluid dynamics with conjugate heat transfer analysis are used to determine the crucial input parameters for further analytical calculations. The heat transfer condition in novel coated design and a conventional fixed bed are compared in the paper. The developed computational model consisted of three subdomains representing heating water, heat exchanger material (copper) and sorbent (silica gel).

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Pezo, Milada, and Vladimir Stevanovic. "Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes." Thermal Science 20, suppl. 1 (2016): 113–23. http://dx.doi.org/10.2298/tsci150701138p.

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This paper presents CFD (Computational Fluid Dynamics) approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surface. Two-phase flow is modelled by the two-fluid model, which consists of the mass, momentum and energy conservation equations for each phase. Interface transfer processes are calculated by the closure laws. Micro level phenomena on the heating surface are modelled with the bubble nucleation site density, the bubble resistance time on the heating wall and with the certain level of randomness in the location of bubble nucleation sites. The developed model was used to determine the heat transfer coefficient and results of numerical simulations are compared with available experimental results and several empirical correlations. A considerable scattering of the predictions of the pool boiling heat transfer coefficient by experimental correlations is observed, while the numerically predicted values are within the range of results calculated by well-known Kutateladze, Mostinski, Kruzhilin and Rohsenow correlations. The presented numerical modeling approach is original regarding both the application of the two-fluid two-phase model for the determination of heat transfer coefficient in pool boiling and the defined boundary conditions at the heated wall surface.

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Pungaiah, Sudalai Suresh, and Chidambara Kuttalam Kailasanathan. "Thermal Analysis and Optimization of Nano Coated Radiator Tubes Using Computational Fluid Dynamics and Taguchi Method." Coatings 10, no. 9 (August 20, 2020): 804. http://dx.doi.org/10.3390/coatings10090804.

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Automotive heat removal levels are of high importance for maximizing fuel consumption. Current radiator designs are constrained by air-side impedance, and a large front field must meet the cooling requirements. The enormous demand for powerful engines in smaller hood areas has caused a lack of heat dissipation in the vehicle radiators. As a prediction, exceptional radiators are modest enough to understand coolness and demonstrate great sensitivity to cooling capacity. The working parameters of the nano-coated tubes are studied using Computational Fluid Dynamics (CFD) and Taguchi methods in this article. The CFD and Taguchi methods are used for the design of experiments to analyse the impact of nano-coated radiator parameters and the parameters having a significant impact on the efficiency of the radiator. The CFD and Taguchi methodology studies show that all of the above-mentioned parameters contribute equally to the rate of heat transfer, effectiveness, and overall heat transfer coefficient of the nanocoated radiator tubes. Experimental findings are examined to assess the adequacy of the proposed method. In this study, the coolant fluid was transmitted at three different mass flow rates, at three different coating thicknesses, and coated on the top surface of the radiator tubes. Thermal analysis is performed for three temperatures as heat input conditioning for CFD. The most important parameter for nanocoated radiator tubes is the orthogonal array, followed by the Signal-to-Noise Ratio (SNRA) and the variance analysis (ANOVA). A proper orthogonal array is then selected and tests are carried out. The findings of ANOVA showed 95% confidence and were confirmed in the most significant parameters. The optimal values of the parameters are obtained with the help of the graphs.

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Amiri, Leyla, Marco Antonio Rodrigues de Brito, Seyed Ali Ghoreishi-Madiseh, Navid Bahrani, Ferri P. Hassani, and Agus P. Sasmito. "Numerical Evaluation of the Transient Performance of Rock-Pile Seasonal Thermal Energy Storage Systems Coupled with Exhaust Heat Recovery." Applied Sciences 10, no. 21 (November 3, 2020): 7771. http://dx.doi.org/10.3390/app10217771.

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This study seeks to investigate the concept of using large waste rocks from mining operations as waste-heat thermal energy storage for remote arctic communities, both commercial and residential. It holds its novelty in analyzing such systems with an experimentally validated transient three-dimensional computational fluid dynamics and heat transfer model that accounts for interphase energy balance using a local thermal non-equilibrium approach. The system performance is evaluated for a wide range of distinct parameters, such as porosity between 0.2 and 0.5, fluid velocity from 0.01 to 0.07 m/s, and the aspect ratio of the bed between 1 and 1.35. It is demonstrated that the mass flow rate of the heat transfer fluid does not expressively impact the total energy storage capacity of the rock mass, but it does significantly affect the charge/discharge times. Finally, it is shown that porosity has the greatest impact on both fluid flow and heat transfer. The evaluations show that about 540 GJ can be stored on the bed with a porosity of 0.2, and about 350 GJ on the one with 0.35, while the intermediate porosity leads to a total of 450 GJ. Additionally, thermal capacity is deemed to be the most important thermophysical factor in thermal energy storage performance.

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Qiu, Facheng, Xianming Zhang, Xinjie Chai, Yingying Dong, Xingjuan Xie, Zuohua Liu, Renlong Liu, and Wensheng Li. "Simulation of Mass and Heat Transfer of Droplets Collision in a Flash Evaporation Pattern." International Journal of Chemical Engineering 2023 (February 10, 2023): 1–13. http://dx.doi.org/10.1155/2023/3574285.

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The behavior of droplets collision in a flash evaporation ambient widely exists in various fields. In this work, the deformation analysis and thermal analysis models were established under the condition of flash via a computational fluid dynamics (CFD) method. First, the effects of initial temperature and collision velocity on heat and mass transfer during evaporation were considered. Then, the morphology change of the liquid phase, the mass change, and their influencing factors during the droplet evaporation process were analyzed. A very good agreement is observed between the results of this paper and the published literature. The results show that the interaction between the initial collision velocity and the initial temperature affects the heat and mass transfer performance. The initial collision velocity influences the heat and mass transfer process of the evaporating droplet by affecting the deformation characteristics of the droplet. The collision velocity and the liquid temperature have a competitive relationship with the evaporation process. Under a low-initial temperature, the collision velocity played a leading role in the evaporation of the liquid phase and the mass transfer of steam.

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Azari, Ahmad, Abdorrasoul Bahraini, and Saeideh Marhamati. "A CFD technique to investigate the chocked flow and heat transfer characteristic in a micro-channel heat sink." International Journal of Computational Materials Science and Engineering 04, no. 02 (June 2015): 1550007. http://dx.doi.org/10.1142/s2047684115500074.

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In this research, a Computational Fluid Dynamics (CFD) technique was used to investigate the effect of choking on the flow and heat transfer characteristics of a typical micro-channel heat sink. Numerical simulations have been carried out using Spalart–Allmaras model. Comparison of the numerical results for the heat transfer rate, mass flow rate and Stanton number with the experimental data were conducted. Relatively good agreement was achieved with maximum relative error 16%, and 8% for heat transfer and mass flow rate, respectively. Also, average relative error 9.2% was obtained for the Stanton number in comparison with the experimental values. Although, the results show that the majority of heat was transferred in the entrance region of the channel, but the heat transfer in micro-channels can also be affected by choking at channel exit. Moreover, the results clearly show that, the location where the flow is choked (at the vicinity of the channel exit) is especially important in determining the heat transfer phenomena. It was found that Spalart–Allmaras model is capable to capture the main features of the choked flow. Also, the effects of choking on the main characteristics of the flow was presented and discussed.

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Khamooshi, Mehrdad, David F. Fletcher, Hana Salati, Sara Vahaji, Shaun Gregory, and Kiao Inthavong. "Computational assessment of the nasal air conditioning and paranasal sinus ventilation from nasal assisted breathing therapy." Physics of Fluids 34, no. 5 (May 2022): 051912. http://dx.doi.org/10.1063/5.0090058.

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Nasal cannula oxygen therapy is a common treatment option for patients with respiratory failure but needs further investigation to understand its potential for use for assisted breathing. Air with a high oxygen level is introduced into the nasal cavity using a nasal cannula during assisted breathing via oxygen therapy. The treatment impacts the nasal airflow dynamics and air-conditioning function. This study aims to investigate the nasal heat and mass transfer and sinus ventilation during assisted breathing at different operating conditions using computational fluid dynamics simulations. The nasal geometry was reconstructed from high-resolution computed tomography scans of a healthy subject. A constant inhalation flow rate of 15 LPM (liters per minute) was used, and the nasal cannula flow rate was set to between 5 and 15 LPM. The results demonstrated that assisted breathing at a high flow rate impacted sinus ventilation. It also changed the mucosal surface heat and mass transfer, thus inhaled air temperature and humidity. The high flow assisted breathing at 36 °C affected the nasal heat flux the most compared with other breathing conditions, while the low flow assisted breathing had minimal effect and, therefore, could be considered ineffective for any relevant treatment.

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Kulkarni, Kaustubh G., Sanjay N. Havaldar, and Harsh V. Malapur. "Numerical Analysis of Central Solar Receivers with Various Geometries." International Journal of Heat and Technology 40, no. 1 (February 28, 2022): 339–46. http://dx.doi.org/10.18280/ijht.400141.

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Concentrated solar power (CSP) is a cutting-edge method of conserving renewable energy. The concentrated solar power is utilized as a heating source to increase the temperature of heat transfer fluid circulating in the piping of the central solar receiver. The solar central receiver is the most crucial part in solar tower power plants. In this study, a Computational Fluid Dynamics (CFD) framework was developed for analyzing four designs of the central tower receiver, namely, a conventional uniform tube diameter solar receiver (UTD), vertical variable tube diameter solar receiver (VTD), a circular solar variable tube diameter (CVTD) receiver and a leaf type circular solar receiver (LTSR). This analysis studied the solar radiation heat transfer efficiency, temperature distribution, and fluid outlet temperature; pressure and velocity distributions for the designs using CFD. It was found that the CVTD design helped achieve a higher rise in temperature of the heat transfer fluid (HTF) when the mass flow rate was in the range of 0.1 to 0.2 liter per minute. The CVTD and LSTR models of receiver were more efficient heat transfer receiver designs compared with other designs for same surface area and strength of beam radiations.

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Sadripour, Maryam, Amir Rahimi, and Mohammad Sadegh Hatamipour. "CFD Modeling and Experimental Study of a Spray Dryer Performance." Chemical Product and Process Modeling 9, no. 1 (June 1, 2014): 15–24. http://dx.doi.org/10.1515/cppm-2013-0034.

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Abstract The performance of a pilot-scale spray dryer is investigated experimentally and theoretically. The governing equations for flow field, heat and mass transfer, and particle trajectory are solved by applying computational fluid dynamics (CFD). The effects of inlet air temperature and initial particle diameter on the outlet humidity and particle residence time are examined. These parameters should be considered carefully in proper designing of spray dryers especially for the heat-sensitive products. The model is validated with an error of 5.5%.

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Arrighetti, Cinzio, Stefano Cordiner, and Vincenzo Mulone. "Heat and Mass Transfer Evaluation in the Channels of an Automotive Catalytic Converter by Detailed Fluid-Dynamic and Chemical Simulation." Journal of Heat Transfer 129, no. 4 (July 12, 2006): 536–47. http://dx.doi.org/10.1115/1.2709657.

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The role of numerical simulation to drive the catalytic converter development becomes more important as more efficient spark ignition engines after-treatment devices are required. The use of simplified approaches using rather simple correlations for heat and mass transfer in a channel has been widely used to obtain computational simplicity and sufficient accuracy. However, these approaches always require specific experimental tuning so reducing their predictive capabilities. The feasibility of a computational fluid dynamics three-dimensional (3D) model coupled to a surface chemistry solver is evaluated in this paper as a tool to increase model predictivity then allowing the detailed study of the performance of a catalytic converter under widely varying operating conditions. The model is based on FLUENT to solve the steady-state 3D transport of mass, momentum and energy for a gas mixture channel flow, and it is coupled to a powerful surface chemistry tool (CANTERA). Checked with respect to literature available experimental data, this approach has proved its predictive capabilities not requiring an ad hoc tuning of the parameter set. Heat and mass transfer characteristics of channels with different section shapes (sinusoidal, hexagonal, and squared) have then been analyzed. Results mainly indicate that a significant influence of operating temperature can be observed on Nusselt and Sherwood profiles and that traditional correlations, as well as the use of heat/mass transfer analogy, may give remarkable errors (up to 30% along one-third of the whole channel during light-off conditions) in the evaluation of the converter performance. The proposed approach represents an appropriate tool to generate local heat and mass transfer correlations for less accurate, but more comprehensive, 1D models, either directly during the calculation or off-line, to build a proper data base.

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Yaïci, Wahiba, and Evgueniy Entchev. "Coupled unsteady computational fluid dynamics with heat and mass transfer analysis of a solar/heat-powered adsorption cooling system for use in buildings." International Journal of Heat and Mass Transfer 144 (December 2019): 118648. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118648.

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Fu, Junpeng, and Jiuju Cai. "Study of Heat Transfer and the Hydrodynamic Performance of Gas–Solid Heat Transfer in a Vertical Sinter Cooling Bed Using the CFD-Taguchi-Grey Relational Analysis Method." Energies 13, no. 9 (May 2, 2020): 2225. http://dx.doi.org/10.3390/en13092225.

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The vertical sinter cooling bed (VSCB) is a high-efficiency energy-saving and environmentally friendly waste heat recovery equipment. In this study, a computational fluid dynamics (CFD) convection model was established to reveal the typical factors on the thermodynamic performance in VSCB. Indeed, a multiple performance optimal algorithm based on the Taguchi-grey relational analysis (GRA) method was first applied to investigate the effects of geometric and operational factors, including the diameter of the bed, height of the bed, air mass flow rate, air inlet temperature, and sinter mass flow rate, on improving the heat transfer (Ex) and hydrodynamic performance (Pdrop) and obtain the optimum combination of each factor in VSCB. The results found that the diameter of the bed was the most influential factor contributing the multiple types of performance with a contribution rate of 70.51%, followed by the air mass flow rate (15.84%), while the height of the bed (0.27%) exerted a limited effect on the performance of multiple processes. The optimal combination of factors (A1B5C5D5E1) was compared with the initially selected parameters by performing a confirmation test. The performances of heat transfer and hydrodynamics were improved by the Taguchi with the GRA method.

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Luzi, Giovanni, and Christopher McHardy. "Modeling and Simulation of Photobioreactors with Computational Fluid Dynamics—A Comprehensive Review." Energies 15, no. 11 (May 27, 2022): 3966. http://dx.doi.org/10.3390/en15113966.

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Computational Fluid Dynamics (CFD) have been frequently applied to model the growth conditions in photobioreactors, which are affected in a complex way by multiple, interacting physical processes. We review common photobioreactor types and discuss the processes occurring therein as well as how these processes have been considered in previous CFD models. The analysis reveals that CFD models of photobioreactors do often not consider state-of-the-art modeling approaches. As a comprehensive photobioreactor model consists of several sub-models, we review the most relevant models for the simulation of fluid flows, light propagation, heat and mass transfer and growth kinetics as well as state-of-the-art models for turbulence and interphase forces, revealing their strength and deficiencies. In addition, we review the population balance equation, breakage and coalescence models and discretization methods since the predicted bubble size distribution critically depends on them. This comprehensive overview of the available models provides a unique toolbox for generating CFD models of photobioreactors. Directions future research should take are also discussed, mainly consisting of an extensive experimental validation of the single models for specific photobioreactor geometries, as well as more complete and sophisticated integrated models by virtue of the constant increase of the computational capacity.

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Shan, Huimin, and Kongqing Li. "Validation and Optimization of Heat and Mass Transfer Model for Mushroom Convection Drying." E3S Web of Conferences 293 (2021): 03011. http://dx.doi.org/10.1051/e3sconf/202129303011.

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In order to solve the problems of time consuming, energy consumption and low simulation accuracy in the hot air-drying system of food drying. Using computational fluid dynamics (CFD) to simulate the drying process of mushrooms can provide a reference for its technology research and development (R&D). The porous media approach was used to model the flow resistance offered by the mushroom. The resistance coefficient and porosity were determined through the experiments. Different air supply ways (wind speed, temperature, fresh air volume, reverse air supply period) were simulated and two optimize ways were suggested according the shortest possible drying time. The simulation results are in good agreement with the experimental results. The air supply way of periodic with reverse (SMPR), which means timed alternate the direction of air flow, or the way of mix in fresh air intermittently can effectively shorten the drying time. Considering comprehensively, the optimal air supply way was the mix in fresh air intermittently with fresh air accounts for 30% or SMPR with the period of 2h under the condition of the hot air temperature of 55°C and wind velocity of 0.6m/s.

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Debnath, Pinku, and KM Pandey. "Exergetic efficiency analysis of hydrogen–air detonation in pulse detonation combustor using computational fluid dynamics." International Journal of Spray and Combustion Dynamics 9, no. 1 (June 22, 2016): 44–54. http://dx.doi.org/10.1177/1756827716653344.

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Exergy losses during the combustion process, heat transfer, and fuel utilization play a vital role in the analysis of the exergetic efficiency of combustion process. Detonation is thermodynamically more efficient than deflagration mode of combustion. Detonation combustion technology inside the pulse detonation engine using hydrogen as a fuel is energetic propulsion system for next generation. In this study, the main objective of this work is to quantify the exergetic efficiency of hydrogen–air combustion for deflagration and detonation combustion process. Further detonation parameters are calculated using 0.25, 0.35, and 0.55 of [Formula: see text] mass concentrations in the combustion process. The simulations have been performed for converging the solution using commercial computational fluid dynamics package Ansys Fluent solver. The details of combustion physics in chemical reacting flows of hydrogen–air mixture in two control volumes were simulated using species transport model with eddy dissipation turbulence chemistry interaction. From these simulations it was observed that exergy loss in the deflagration combustion process is higher in comparison to the detonation combustion process. The major observation was that pilot fuel economy for the two combustion processes and augmentation of exergetic efficiencies are better in the detonation combustion process. The maximum exergetic efficiency of 55.12%, 53.19%, and 23.43% from deflagration combustion process and from detonation combustion process, 67.55%, 57.49%, and 24.89%, are obtained from aforesaid [Formula: see text] mass fraction. It was also found that for lesser fuel mass fraction higher exergetic efficiency was observed.

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Khan, Abdullah, Imran Shah, Waheed Gul, Tariq Amin Khan, Yasir Ali, and Syed Athar Masood. "Numerical and Experimental Analysis of Shell and Tube Heat Exchanger with Round and Hexagonal Tubes." Energies 16, no. 2 (January 12, 2023): 880. http://dx.doi.org/10.3390/en16020880.

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Shell and tube heat exchangers are used to transfer thermal energy from one medium to another for regulating fluid temperatures in the processing and pasteurizing industries. Enhancement of a heat transfer rate is desired to maximize the energy efficiency of the shell and tube heat exchangers. In this research work, we performed computational fluid dynamics (CFD) simulations and experimental analysis on the shell and tube heat exchangers using round and hexagonal tubes for a range of flow velocities using both parallel flow and counter flow arrangements. In the present work, the rate of heat transfer, temperature drop, and heat transfer coefficient are computed using three turbulence models: the Spalart–Allmaras, the k-epsilon (RNG), and the k-omega shear stress transport (SST). We further utilized the logarithmic mean temperature difference (LMTD) method to compute the heat transfer and mass flow rates for both parallel and counter flow arrangements. Our results show that the rate of heat transfer is increased by introducing the hexagonal structure tubes, since it has better flow disruption as compared to the round tubes. We further validated our simulation results with experiments. For more accurate results, CFD is performed in counter and parallel flow and it is deduced that the rate of heat transfer directly depends upon the velocity of fluids and the number of turns of the tube.

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Araújo, Morgana Vasconcellos, Alanna C. Sousa, Marcia R. Luiz, Adriano S. Cabral, Thayze Rodrigues Bezerra Pessoa, Pierre Correa Martins, Anderson Melchiades Vasconcelos da Silva, R. S. Santos, Vital Araújo Barbosa de Oliveira, and Antonio Gilson Barbosa de Lima. "Computational Fluid Dynamics Studies in the Drying of Industrial Clay Brick: The Effect of the Airflow Direction." Diffusion Foundations and Materials Applications 30 (August 19, 2022): 69–84. http://dx.doi.org/10.4028/p-j1eci6.

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The manufacture of ceramic brick goes through the stages of raw material extraction, clay homogenization, material conformation, drying and firing. Drying is the phase that needs greater care, as it involves removing part of the moisture from the brick, in order to preserve its quality after process. This work aims to predict heat and mass transfer in the drying of ceramic bricks in oven using computational fluid dynamics. Considering the constant thermophysical properties, a transient three-dimensional mathematical model was used to predict mass and energy transfer between the material and air during the process. Drying simulations at temperature of 100°C were performed with the air flow in the frontal direction to the ceramic brick holes and the results were compared with those obtained for the air flow in the perpendicular direction to the brick holes reported in the literature. It was found that the position of the brick in relation to the direction of air flow inside the oven affected directly the drying and heating kinetics, and the distribution of temperature and moisture content inside the brick. The positioning of the holes in the brick parallel to the direction of the air flow resulted in reduction at the drying time and, consequently, in energy savings in the process, more uniform drying, and improvement in the product quality.

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Alsahil, Muath I., Mowffaq M. Oreijah, and Mohamed H. Mohamed. "Quantitative and Qualitative Study of Double-Pipe Heat Exchangers Performance Using Water Based Nanofluids." Journal of Nanofluids 11, no. 6 (December 1, 2022): 924–43. http://dx.doi.org/10.1166/jon.2022.1891.

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The heat transfer performance of base fluids is greatly improved with suspended nanoparticles in a variety of applications such as solar collectors, heat pipes, nuclear reactors, cooling systems, automotive radiators, and more. In the present paper, the problem of flow of nanofluids with forced convection is studied in detail in three cases, under constant mass flow rates (Case 1), under optimized mass flow rates with two different geometric configuration scenarios of the heat exchangers, N-shaped pipe heat exchanger (Case 2) and M-shaped pipe heat exchanger (Case 3). Numerical results in the previous works, as obtained for water–Al2O3 mixture, have been demonstrated that of nanoparticles into the base fluids fluid led to a significant increase of the heat transfer coefficient, which clearly increases with an increase in particle concentration. However, those particals also caused drastic effects on the wall shear stress that increases correspondingly with the particle loading. Therefore, in the current study the full performance of the different heat exchanger designs will be investigated numerically under the effect of different particle concentrations and different nano materials such as Al2O3, CuO, TiO2 and SiO2. Additionally, the Computational Fluid Dynamics (CFD) single-phase model is adopted for predicting the heat transfer performance in fluent using ANSYS. Therefore, the results show enhancement in heat transfer for the heat exchanger is due to increased volume fraction, and a direct correlation between overall heat transfer effectiveness and volume fraction percentage of nanofluids, while CuO was proven most effective amongst considered nano particles. Besides, adjusting the geometry into an M-shaped pipe had resulted in an enhanced heat transfer effectiveness.

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POVITSKY, ALEX. "FLUID DYNAMICS ISSUES IN SYNTHESIS OF CARBON NANOTUBES." International Journal of Nanoscience 04, no. 01 (February 2005): 73–98. http://dx.doi.org/10.1142/s0219581x0500295x.

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The majority of carbon nanotubes' synthesis processes occur in the presence of fluid (liquid, gas, plasma, or multi-phase flow) that may function as a carrier of catalyst particles, feedstock of carbon, and the heating or cooling agent. The fluid motion defines the temperature of catalyst particles and the local chemical composition of the fluid that determines the success of synthesis of high-purity nanotubes. In this review paper, the laser ablation process, high-pressure carbon oxide process, and chemical vapor deposition process are considered from the prospective of fluid dynamics modeling. The multi-model approach should be used for concurrent rendering of different areas of computational domain by different models and/or different time steps for the same model. For multiple plume ejection in laser ablation, the near-target area could be rendered by molecular dynamics approach whereas continuous gas dynamics algorithms should be employed to simulate plume dynamics of previously ejected plumes apart of the target. Such an approach combines continuous mechanics of multi-species flow of feedstock gas or plume; micro-fluidic flow model that is needed to find heat and mass transfer rate to catalysts in presence of individual nanotubes in close proximity to each other; and molecular dynamics of evaporation and ejection of plume in laser ablation.

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Journal articles on the topic 'Heat and mass transfer (incl. computational fluid dynamics)'

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