Dissertations / Theses on the topic 'Heat and mass transfer (incl. computational fluid dynamics)'
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Reichrath, Sven. "Convective heat and mass transfer in glasshouses." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391213.
Full textBurt, Andrew C. "A computational study of mixing in stratified liquid-liquid flows using analogy between heat and mass transfer." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1948.
Full textTitle from document title page. Document formatted into pages; contains x, 76 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 71-72).
Guardo, Zabaleta Alfredo. "Computational Fluid Dynamics Studies in Heat and Mass Transfer Phenomena in Packed Bed Extraction and Reaction Equipment: Special Attention to Supercritical Fluids Technology." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6455.
Full textLa Dinámica de Fluidos Computacional (CFD) como herramienta de modelado numérico permite obtener una visión mas aproximada y realista de los fenómenos de flujo de fluidos y los mecanismos de transferencia de calor y masa en lechos empacados, a través de la resolución de las ecuaciones de Navier - Stokes acopladas con los balances de materia y energía y con un modelo de turbulencia si es necesario. De esta forma, esta herramienta permite obtener los valores medios y/o fluctuantes de variables como la velocidad del fluido, la temperatura o la concentración de una especie en cualquier punto de la geometría del lecho empacado.
El objetivo de este proyecto es el de utilizar programas comerciales de simulación CFD para resolver el flujo de fluidos y la transferencia de calor y de masa en modelos bi/tri dimensionales de lechos empacados, desarrollando una estrategia de modelado aplicable al diseño de equipos para procesos de extracción o de reacción catalítica. Como referencia se tomaran procesos de tecnología supercrítica debido a la complejidad de los fenómenos de transporte involucrados en estas condiciones, así como a la disponibilidad de datos experimentales obtenidos previamente en nuestro grupo de investigación. Estos datos experimentales se utilizan como herramienta de validación de los modelos numéricos generados, y de las estrategias de simulación adoptadas y realizadas durante el desarrollo de este proyecto.
An understanding of the heat and mass transfer phenomena in a porous media implies the study of the fluid transport model within the void space; this fact is of fundamental importance to many chemical engineering systems such as packed bed extraction or catalytic reaction equipment. Experimental and theoretical studies of flow through such systems often treat the porous medium as an effectively homogeneous system and concentrate on the bulk properties of the flow. Such an approach neglects completely the complexities of the flow within the void space of the porous medium, reducing the description of the problem to macroscopic average or effective quantities. The details of this local flow process may, however, be the most important factor influencing the behavior of a given physical process occurring within the system, and are crucial to understanding the detailed mechanisms of, for example, heat and mass dispersion and interface transport.
Computational Fluid Dynamics as a simulation tool allows obtaining a more approached view of the fluid flow and heat and mass transfer mechanisms in fixed bed equipment, through the resolution of 3D Reynolds averaged transport equations, together with a turbulence model when needed. In this way, this tool permit to obtain mean and fluctuating flow and temperature values in any point of the bed.
The goal of this project is to use commercial available CFD codes for solving fluid flow and heat and mass transfer phenomena in two and three dimensional models of packed beds, developing a modeling strategy applicable to the design of packed bed chemical reaction and extraction equipment. Supercritical extraction and supercritical catalytic reaction processes will be taken as reference processes due to the complexity of the transport phenomena involved within this processes, and to the availability of experimental data in this field, obtained in the supercritical fluids research group of this university. The experimental data priory obtained by our research group will be used as validation data for the numerical models and strategies dopted and followed during the developing of the project.
Srinivasan, Raghavan. "CFD Heat Transfer Simulation of the Human Upper Respiratory Tract for Oronasal Breathing Condition." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29310.
Full textBhopte, Siddharth. "Study of transport processes from macroscale to microscale." Diss., Online access via UMI:, 2009.
Find full textIncludes bibliographical references.
Ho, Son Hong. "Numerical modeling and simulation for analysis of convective heat and mass transfer in cryogenic liquid storage and HVAC&R applications." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002266.
Full textHo, Son Hong. "Numerical simulation of thermal comfort and contaminant transport in air conditioned rooms." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000548.
Full textWu, Dan. "A numerical study of periciliary liquid depth in MDCT-based human airway models." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1804.
Full text(9832871), Abu Sayem. "Experimental study of electrostatic precipitator of a coal based power plant to improve performance by capturing finer particles." Thesis, 2019. https://figshare.com/articles/thesis/Experimental_study_of_electrostatic_precipitator_of_a_coal_based_power_plant_to_improve_performance_by_capturing_finer_particles/13408691.
Full text(14042749), Shah M. E. Haque. "Performance study of the electrostatic precipitator of a coal fired power plant: Aspects of fine particulate emission control." Thesis, 2009. https://figshare.com/articles/thesis/Performance_study_of_the_electrostatic_precipitator_of_a_coal_fired_power_plant_Aspects_of_fine_particulate_emission_control/21454428.
Full textParticulate matter emission is one of the major air pollution problems of coal fired power plants. Fine particulates constitute a smaller fraction by weight of the total suspended particle matter in a typical particulate emission, but they are considered potentially hazardous to health because of the high probability of deposition in deeper parts of the respiratory tract. Electrostatic precipitators (ESP) are the most widely used devices that are capable of controlling particulate emission effectively from power plants and other process industries. Although the dust collection efficiency of the industrial precipitator is reported as about 99.5%, an anticipation of future stricter environmental protection agency (EPA) regulations have led the local power station seeking new technologies to achieve the new requirements at minimum cost and thus control their fine particulate emissions to a much greater degree than ever before.
This study aims to identify the options for controlling fine particle emission through improvement of the ESP performance efficiency. An ESP system consists of flow field, electrostatic field and particle dynamics. The performance of an ESP is significantly affected by its complex flow distribution arising as a result of its complex internal geometry, hence the aerodynamic characteristics of the flow inside an ESP always need considerable attention to improve the efficiency of an ESP. Therefore, a laboratory scale ESP model, geometrically similar to an industrial ESP, was designed and fabricated at the Thermodynamics Laboratory of CQUniversity, Australia to examine the flow behaviour inside the ESP. Particle size and shape morphology analyses were conducted to reveal the properties of the fly ash particles which were used for developing numerical models of the ESP.
Numerical simulations were carried out using Computational Fluid Dynamics (CFD) code FLUENT and comparisons were made with the experimental results. The ESP was modelled in two steps. Firstly, a novel 3D fluid (air) flow was modelled considering the detailed geometrical configuration inside the ESP. A novel boundary condition was applied at the inlet boundary of this model to overcome all previous assumptions on uniform velocity at the inlet boundary. Numerically predicted velocity profiles inside the ESP model are compared with the measured data obtained from the laboratory experiment. The model with a novel boundary condition predicted the flow distribution more accurately. In the second step, as the complete ESP system consists of an electric field and a particle phase in addition to the fluid flow field, a two dimensional ESP model was developed. The electrostatic force was applied to the flow equations using User Defined Functions (UDF). A discrete phase model was incorporated with this two dimensional model to study the effect of particle size, electric field and flue gas flow on the collection efficiency of particles inside the ESP. The simulated results revealed that the collection efficiency cannot be improved by the increased electric force only unless the flow velocity is optimized.
The CFD model was successfully applied to a prototype ESP at the power plant and used to recommend options for improving the efficiency of the ESP. The aerodynamic behaviour of the flow was improved by geometrical modifications in the existing 3D numerical model. In particular, the simulation was performed to improve and optimize the flow in order to achieve uniform flow and to increase particle collection inside the ESP. The particles injected in the improved flow condition were collected with higher efficiency after increasing the electrostatic force inside the 2D model. The approach adopted in this study to optimize flow and electrostatic field properties is a novel approach for improving the performance of an electrostatic precipitator.
(5929775), Kenny Sy Hu. "Large-Eddy Simulation And RANS Studies Of The Flow And Heat Transfer In A U-Duct With Trapezoidal Cross Section." Thesis, 2019.
Find full text"Computational Fluid Dynamics Studies in Heat and Mass Transfer Phenomena in Packed Bed Extraction and Reaction Equipment: Special Attention to Supercritical Fluids Technology." Universitat Politècnica de Catalunya, 2007. http://www.tesisenxarxa.net/TDX-0515107-124052/.
Full text(8115878), Matthew T. Moore. "Numerical Simulation of a Continuous Caster." Thesis, 2019.
Find full text(6630413), Aashutosh Mistry. "Mesoscale Interactions in Porous Electrodes." Thesis, 2019.
Find full text(11002410), Ziyang Huang. "CONSISTENT AND CONSERVATIVE PHASE-FIELD METHOD FOR MULTIPHASE FLOW PROBLEMS." Thesis, 2021.
Find full text(8083571), Veeraraghava Raju Hasti. "HIGH-PERFORMANCE COMPUTING MODEL FOR A BIO-FUEL COMBUSTION PREDICTION WITH ARTIFICIAL INTELLIGENCE." Thesis, 2019.
Find full textThe main accomplishments of this research are
(1) developed a high fidelity computational methodology based on large eddy simulation to capture lean blowout (LBO) behaviors of different fuels;
(2) developed fundamental insights into the combustion processes leading to the flame blowout and fuel composition effects on the lean blowout limits;
(3) developed artificial intelligence-based models for early detection of the onset of the lean blowout in a realistic complex combustor.
The methodologies are demonstrated by performing the lean blowout (LBO) calculations and statistical analysis for a conventional (A-2) and an alternative bio-jet fuel (C-1).
High-performance computing methodology is developed based on the large eddy simulation (LES) turbulence models, detailed chemistry and flamelet based combustion models. This methodology is employed for predicting the combustion characteristics of the conventional fuels and bio-derived alternative jet fuels in a realistic gas turbine engine. The uniqueness of this methodology is the inclusion of as-it-is combustor hardware details such as complex hybrid-airblast fuel injector, thousands of tiny effusion holes, primary and secondary dilution holes on the liners, and the use of highly automated on the fly meshing with adaptive mesh refinement. The flow split and mesh sensitivity study are performed under non-reacting conditions. The reacting LES simulations are performed with two combustion models (finite rate chemistry and flamelet generated manifold models) and four different chemical kinetic mechanisms. The reacting spray characteristics and flame shape are compared with the experiment at the near lean blowout stable condition for both the combustion models. The LES simulations are performed by a gradual reduction in the fuel flow rate in a stepwise manner until a lean blowout is reached. The computational methodology has predicted the fuel sensitivity to lean blowout accurately with correct trends between the conventional and alternative bio-jet fuels. The flamelet generated manifold (FGM) model showed 60% reduction in the computational time compared to the finite rate chemistry model.
The statistical analyses of the results from the high fidelity LES simulations are performed to gain fundamental insights into the LBO process and identify the key markers to predict the incipient LBO condition in swirl-stabilized spray combustion. The bio-jet fuel (C-1) exhibits significantly larger CH2O concentrations in the fuel-rich regions compared to the conventional petroleum fuel (A-2) at the same equivalence ratio. It is observed from the analysis that the concentration of formaldehyde increases significantly in the primary zone indicating partial oxidation as we approach the LBO limit. The analysis also showed that the temperature of the recirculating hot gases is also an important parameter for maintaining a stable flame. If this temperature falls below a certain threshold value for a given fuel, the evaporation rates and heat release rated decreases significantly and consequently leading to the global extinction phenomena called lean blowout. The present study established the minimum recirculating gas temperature needed to maintain a stable flame for the A-2 and C-1 fuels.
The artificial intelligence (AI) models are developed based on high fidelity LES data for early identification of the incipient LBO condition in a realistic gas turbine combustor under engine relevant conditions. The first approach is based on the sensor-based monitoring at the optimal probe locations within a realistic gas turbine engine combustor for quantities of interest using the Support Vector Machine (SVM). Optimal sensor locations are found to be in the flame root region and were effective in detecting the onset of LBO ~20ms ahead of the event. The second approach is based on the spatiotemporal features in the primary zone of the combustor. A convolutional autoencoder is trained for feature extraction from the mass fraction of the OH ( data for all time-steps resulting in significant dimensionality reduction. The extracted features along with the ground truth labels are used to train the support vector machine (SVM) model for binary classification. The LBO indicator is defined as the output of the SVM model, 1 for unstable and 0 for stable. The LBO indicator stabilized to the value of 1 approximately 30 ms before complete blowout.Τζεμπελίκος, Δημήτριος. "Υπολογιστική και πειραματική διερεύνηση φαινομένων μεταφοράς μάζας και θερμότητας σε πρότυπη εργαστηριακή εγκατάσταση μηχανικής ξήρανσης." Thesis, 2015. http://hdl.handle.net/10889/8598.
Full textThe objective subject of this thesis is the computational and experimental investigation of heat and mass transfer phenomena in a new laboratory mechanical convection drying unit, which was designed, constructed and equipped with measuring equipment and an integrated control system of collection and processing of experimental measurements. In laboratory drying unit there is an option to change and control the main parameters of which affected the thermal drying process, such as speed, temperature and humidity of the drying air. Measurement of the removal of moisture content in the dried product is carried out through high-precision load cells, and the spatial distribution of the flow velocity at the entrance of the drying chamber during of each experiment, is continuously measured by pitot tube array and a system composed of solenoids and a pressure transducer. The spatial distribution of temperature and velocity in the drying chamber is possible by means of sensors fitted to a computer controlled cartesian motion system which is designed, constructed and placed at the outlet of the vertical drying chamber, constituting an integral part of the facility. All measurements were performed on the vertical drying chamber while it is possible to conduct measurements in a horizontal layout of the drying chamber. In this thesis became systematic experimental investigation of convective drying sliced quince and studied the effect of various parameters affecting the thermal drying process in this agricultural product, for air temperatures of 40, 50 and 60°C and air velocities 1, 2 and 3 m/s. The purpose of the measurements was to determine: (i) the effect of temperature and air velocity in drying curves of cylindrical quince slice, (ii) the effect of the thickness of the cylindrical slice of quince in drying curves, (iii) the effect of the orientation of the cylindrical quince slice, in the direction of incident flow, in the drying curves (iv) the adjusting of the drying curves in several simple thin layer drying models v) the effective moisture diffusivity coefficients for each case with the slope method which correlated with the temperature of the drying air so that the diffusion coefficient of moisture be expressed by Arrhenius type equation form and vi ) the interfacial heat and mass transfer coefficients which expressed as a function of dimensionless numbers Nu, Re and Pr in the form Nu = aRebPr1/3. The simulation of the flow and temperature fields in the drying chamber and the calcu-lation of the interfacial heat and mass transfer coefficients around the surface of the product were performed using the tools of Computational Fluid Dynamics (CFD). CFD simulations were steady state, considering turbulent flow while drying chamber and cy-lindrical slice of quince specialized as an axisymmetric two-dimensional configuration. As turbulence model was used the SST k-ω model while on the approximation of the boundary layer near the walls of the product the LRNM was chosen. By solving the flow and temperature fields determined distributions of interfacial heat and mass transfer coefficients in front and rear of the cylindrical slice of quince for all experimental conditions. The calculation of the weighted average prices of the interfacial heat transfer coefficient indicates a correlation between dimensionless numbers Nu, Re and Pr, in the form Nu = aRebPr1/3, which as finding enriches the existing literature. In the final stage of the thesis, developed and evaluated in comparison with the experi-mental measurements, a one-dimensional transient numerical model of heat and mass transfer to simulate drying curves in cylindrical slices of quince. The heat transfer inside the quince is considered to be by conduction while the moisture transfer is considered to be governed solely by liquid diffusion. Evaporation is considered to take place only from the windward and leeward surface of the quince slice. The numerical model takes into account the shrinkage of the cylindrical slice of quince, assuming that the cylindrical volume decreases each time as much as the volume of water that evaporates on both surfaces of the slice. The numerical code used the thermophysical properties of quince and air from the literature, the effective diffusion coefficient of moisture experimentally determined by the method of the slopes, while the transfer coefficients used the weighted average prices of interfacial heat and mass transfer coefficients derived from the simulations with CFD (non-conjugated approach). In order to achieve higher accuracy between experimental data and predictions, a non-linear regression analysis, using an Arrhenius type effective diffusion equation, was also performed. However, preliminary result, obtained using the SQP (Sequential Quadratic Programming) and Interior Point algorithms for the minimization of the Chi-square function (χ2) showed only small improvement of the calculated results with a significant increase of the computational cost. In conclusion, the overall assessment of the results of the numeric code shown that the proposed numerical model based on diffusion is able to effectively describe the coupling of heat transfer and mass, as to capture the time evolution of moisture content and temperature within the product, with minimum use of experimental input variables and minimum computational requirements. For these reasons it may be considered appropriate to analyze the convective drying process in any organic or non-organic product.