Дисертації з теми "Evaporatore"
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Schiano-Phan, Rosa. "The development of passive downdraught evaporative cooling systems using porous ceramic evaporators and their application in residential buildings." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417587.
Повний текст джерелаSovernigo, Enrico. "Influence of nanostructured heterojunctions on the electrical properties of photovoltaic cells." Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4480.
Повний текст джерелаLe celle fotovoltaiche basate su strati sottili di materiali organici hanno raggiunto efficienze dell' 8.3% ed hanno le potenzialità per diventare un'alternativa a basso costo delle celle basate su silicio amorfo. Alcune delle problematiche legate alle proprietà intrinseche di generazione, separazione e trasporto delle cariche possono essere affrontate non solo con lo studio della chimica e dei processi per materiali organici e fullerene, ma anche con lo sviluppo di nuove architetture delle celle basate sul controllo e l'organizzazione alla scala del nanometro. Il presente lavoro di tesi è basato sulla convinzione che quest'ultimo approccio, complementare a quello basato sul miglioramento delle proprietà intrinseche dei materiali, contribuirà sostanzialmente al progresso di questo campo della ricerca applicata. L'obiettivo di questo lavoro è quello di dimostrare il principio di funzionamento di una serie di diversi e nuovi prototipi di dispositivi basati su micro- e nano-architetture. In particolare, abbiamo realizzato: un nanomodulo di 1 cm2 che mostra una tensione di circuito aperto di quasi 1 kV, una cella solare basata su un'eterogiunzione con interfaccia avente strutture di 20 nm interpenetrate, e abbiamo ottimizzato deposizione di ossido di indio stagno (ITO) per lo sviluppo di un nostro dispositivo di intrappolamento della luce basato su serie di microlenti. Tuttatavia, riteniamo che ulteriori sforzi nella stessa direzione siano necessari per dimostrare l'utilità delle nano-architetture nel fotovoltaico organico. Parte del lavoro di ricerca è stato dedicato allo sviluppo e messa in opera di strumentazione specifica per la lavorazione e caratterizzazione per il fotovoltaico come un evaporatore in vuoto ad angolo inclinato connesso ad una camera a guanti in azoto per la deposizione di metalli e di organici.
Thin-film photovoltaic (PV) cells based on the bulk hetero-junction of organic materials reached a record efficiency of 8.3% and have the potential to become a lower-cost alternative to amorphous silicon. Some of the issues related to the intrinsic properties of generation, separation and transport of charges, may be addressed not just by working on the details of the chemistry and processing of the organic/fullerenes materials, but also by implementing new cell architectures organized and well controlled down to the nanoscale. The present work of thesis is based on the conviction that the latter approach, complementary to that focused on the improvement of the intrinsic properties of the materials, will substantially contribute to the progress of this field of applied research. The goal of this work is that of demonstrating the working principle of a series of different and new micro- and nano-architectures into prototypical organic solar devices. In particular, we realized: a 1 cm2 nanomodule with almost 1 kV of open circuit voltage, a solar cell with a controlled nanostructured interface heterojunction with interpenetrating features of 20 nm, and we optimized the sputtering deposition of indium tin oxide (ITO) for our light trapping device based on microlenses array. However, we believe that additional efforts in the same direction will be necessary to demonstrate the usefulness of nanoarchitectures in organic photovoltaics. Part of the research work was devoted to the development and the commission of specific instrumentation for PV processing and characterization as an oblique angle vacuum evaporator connected to a nitrogen glove-box for the deposition of metals and organics.
XXIII Ciclo
1980
Howell, John Michael. "Whey permeate fouling of evaporators." Thesis, University of Canterbury. Chemical and Process Engineering, 1998. http://hdl.handle.net/10092/10686.
Повний текст джерелаQuy, Tiffany Anne. "Characterization of micro-capillary wicking evaporators." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/T_Quy_081806.pdf.
Повний текст джерелаLagos, Arcangel. "Heat transfer enhancement in DX evaporators." Thesis, London South Bank University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311210.
Повний текст джерелаKarpiscak, Martin, and Mary H. Marion. "Evaporative Cooler Water Use." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/146414.
Повний текст джерелаMcCafferty, J. B. "Refrigerant distribution in shell and tube evaporators." Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/1027.
Повний текст джерелаWadell, Robert Paul. "Experimental Investigation of Compact Evaporators for Ultra Low Temperature Refrigeration of Microprocessors." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7198.
Повний текст джерелаJin, Dae-Hyun. "Investigation on refrigerant distribution in evaporator manifolds." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3845.
Повний текст джерелаThesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Shepherd, Adrian M. "Safeguarding of evaporator operations in reprocessing plant." Thesis, London South Bank University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411377.
Повний текст джерелаDalili, Farnosh. "Humidification in Evaporative Power Cycles." Doctoral thesis, KTH, Chemical Engineering and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3469.
Повний текст джерелаEvaporative gas turbine cycles (EvGT) show an exceptionalexhaust heat recovery potential, which makes them a strongcompetitor to other advanced gas turbine cycles, especiallyfrom small to intermediate sizes. Evaporative gas turbines aredistinguished by humidifying the working fluid beforecombustion at temperatures below the boiling point of water;and the heat required for evaporation of water is partly takenout of the exhaust gas. Thus, humidification is a key operationin these cycles. This thesis investigates, both theoreticallyand experimentally, two alternative approaches tohumidification: the packed-bed humidification tower and thetubular humidifier. Both these equipments involvecountercurrent contact between water and the working fluid.Humidifier design criteria are developed and criticalparameters such as flooding, wetting rate and entrainment arediscussed. The experimental parts were carried out on thepacked-bed tower in the EvGT pilot plant, and on a tubularhumidifier test rig especially erected for this purpose. Thetheoretical models were confirmed by the experiments.
The height of a transfer unit, necessary for designingpacked beds, was calculated for the packing employed in theEvGT pilot plant. It was found that the data provided by themanufacturer may be used with minor corrections.
The tubular test rig operated satisfactorily delivering hothumid air. The theoretical models coincided well with theexperimental results, verifying the design criteria developedhere. The heat transfer calculations indicated that mostresistance to heat transfer is on the exhaust gas side. Thus, asurface extended tube (Sunrod) was used in the test rig. Itcould be concluded that the tubular humidifier is a strongalternative to the packed-bedtower, especially in smallhigh-pressure gas turbines.
Furthermore, the importance of the non-ideality of theair-water vapor mixture in modeling evaporative cycles wasfirst highlighted in this work. Through applying realthermodynamic properties of air-water vapor mixtures in cyclecalculations, it was found that the compressed air contains ahigher amount of moisture than indicated by the ideal gasmixture model. This affects the design of the heat recoverysystem and cannot be neglected.
Key words:evaporative gas turbine, indirect-fired gasturbine, humidification, packed bed, tubular humidifier,evaporator, saturator.
Davis, Kendall Bruce. "Evaporative cooling of sodium atoms." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11384.
Повний текст джерелаUguz, Kamuran Erdem. "Evaporative instability in binary mixtures." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112169/document.
Повний текст джерелаThis study focuses on understanding the physics of the convective flow resulting from evaporative instability in binary mixtures. This problem has wide applications in spin coating, film deposition, heat pipes, etc. where phase change and convection play a very important role in the design process and also final quality of the product. The physical system of interest consists of a liquid mixture underlying its own vapor sandwiched between two conducting plates with insulated sidewalls in a closed container. The conducting plates are used to apply a vertical temperature gradient while there is no applied concentration gradient in the system. Concentration gradients are induced by the different evaporation rate of the components. In this system it is important to understand how the fluid dynamics and the heat and mass transfer interact competitively to form patterns. The main goal of this work is to identify the conditions for the system going from the conductive no-flow state to a convection state when the applied vertical temperature gradient exceeds a certain value called the critical value.In the system convection arises due to three distinct phenomena; evaporation, density gradients, and interfacial tension gradients. These convective forces are opposed by the diffusion effects that try to keep the system in the conductive no-flow state. The onset point depends upon several variables such as the dimensions of the container, thermo-physical properties of both liquid and vapor phases, mass fraction, and the characteristic of the disturbance given to the system. The effects of each of these variables on the onset point are investigated both in the presence and in the absence of gravity. To represent the physics a complete non-linear mathematical model is developed including momentum, energy, and mass balances in both phases with appropriate boundary conditions. The binary mixture is assumed to be made up of two low weight alcohols such as ethanol and sec-butanol. In the modeling equations the density and the interfacial tension are taken to be function of both temperature and concentration. To identify the onset point the non-linear equations are linearized around a known base state. In this case the base state is the conductive no-flow state. The resulting set of linear equations is solved using a spectral Chebyshev collocation method. Four major results arise from this work. First, in a multi-component system in the absence of gravity, an instability arises only when the system is heated from the vapor side as opposed to evaporation in a single-component. The implication is that evaporative processes in thin layers or in micro-gravity are best conducted with heat from the liquid side if instabilities are to be avoided.Second, in the presence of gravity, a multi-component system may become unstable no matter the direction of heating. If thermal buoyancy is negligible then it is shown in this study that heating from the vapor side is the unstable arrangement. Otherwise either heating style can produce an instability. This result means that the applied temperature difference must be kept below a threshold in order to avoid flow instabilities no matter the heating direction.Third, whenever instability occurs in the absence of gravity, patterns will not result in the case of a pure component but may result in the case of multi-components. Likewise, patterns will result when gravity is taken into account provided the aspect ratio of the container lies in a suitable range. As a result, aspect ratios can be chosen to avoid multi-cellular patterns even if convective flow instabilities arise during evaporation.Lastly, oscillations are not ordinarily predicted despite opposing effects of solutaland thermal convection in the evaporation problem
Alexseev, Alexandre Viktorovich. "Micro loop heat pipe evaporator coherent pore structures." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1303.
Повний текст джерелаIngebrigtsen, Vegard Byre. "Energy Analysis of Evaporator System in Fertilizer Production." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18410.
Повний текст джерелаSuren, Aydin. "Scaling of black liquor in falling film evaporator." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/10147.
Повний текст джерелаYoung, B. R. "Modelling and identification of a climbing film evaporator." Thesis, University of Canterbury. Chemical and Process Engineering, 1992. http://hdl.handle.net/10092/7522.
Повний текст джерелаSmith, Patrick D. "Control and optimization of a multiple-effect evaporator." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5397.
Повний текст джерелаFalling commodity prices have reduced the profit margins of Southern African sugar producers. Although these price falls have been severe, they reflect a long-term trend of reducing margins for basic commodity producers during the 20th Century. This trend has forced. producers to closely examine their processes and to look for areas in which improvements in productivity, yield and efficiency can be achieved. Evaporation is the most energy intensive unit operation in the sugar factory, and it is responsible for the removal of most of the water from sugar solution, or juice, which is extracted from the sugar cane. There is also a large potential to lose sucrose at the evaporators due to the high temperatures and long residence times employed there. The smooth control of the evaporators is thus vital to consistent factory operation, and the evaporators are commonly a sugar factory bottleneck. This study developed a control strategy for the particular evaporator configuration found at Triangle Sugar Mill in south eastern Zimbabwe. There are currently several evaporator control strategies being used in the sugar industry. Most of these are an assembly of single loop Proportional Integral Derivative (PID) controllers, which cannot optimally account for the interactions encountered in most evaporator stations. Ideally, any evaporator control system should be able to handle the multiple input multiple output problem while anticipating and handling constraints on inputs and outputs. Several multivariable approaches have been tried, but these usually require a great deal of expensive instrumentation.After a review of the multivariable control literature and testing of several alternative control systems, Dynamic Matrix Control (DMC) was chosen as the bestwsuited control algorithm for the Triangle control problem. A dynamic model of the Triangle evaporator station was, developed to formulate and test the DMC and other controllers. The model was based on a set of differential equations involving mass and energy balances through the evaporators. Real plant data were collected from the SCADA system and the model was tested against this data. After validation the model was. used to record step responses of the process to key input variables. The control system had nine (9) measurable inputs, and three (3) controlled outputs. The objective of the control system was to deliver the maximum amount of consistently high quality symp, within plant constraints. This was formulated in an objective function which seeks to minimize a weighted sum of the errors of syrup concentration from a setpoint, and the fluctuations in juice flowrates. Two alternative formulations were developed, and tested on the plant model.
Qiu, Guoquan. "A novel evaporative/desiccant cooling system." Thesis, Nottingham Trent University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444606.
Повний текст джерелаGuerra, Zuimdie. "Evaporative air conditioner for automotive application." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35980.
Повний текст джерелаDreyer, Andre Alexis. "Analysis of evaporative coolers and condensers." Thesis, Stellenbosch : Stellenbosch University, 1988. http://hdl.handle.net/10019.1/66038.
Повний текст джерелаENGLISH ABSTRACT: In this report various mathematical models for the thermal evaluation of evaporative coolers and condensers are presented. These models range from the exact model based on the work by Poppe [84P01] to the simplified logarithmic models based on the work of McAdams [54Mcl] and Mizushina et al. [67MI1], [68MI1]. Various computer programs were written to perform rating and selection calculations on cross-flow and counterflow evaporative coolers and condensers. Experimental tests were conducted on a cross-flow evaporative cooler to determine the governing heat and mass transfer coefficients. The experimentally determined coefficients were cqrrelated and these correlations are compared to the existing correlations. The two-phase pressure drop across the tube bundle was also measured and a correlation for two-phase pressure drop across a tube bundle is presented.
Giacomelli, Gene, and Kathryn Hahne. "Evaporative Cooling in Semi-Arid Climates." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/146294.
Повний текст джерелаIn the semi-arid climate of southern AZ, evaporative cooling systems are commonly used and very effective for cooling homes (swamp coolers), outdoor areas (misters), and for greenhouses used for commercial and horticultural plant production (pad-and-fan, high-pressure-fog). The purpose of this brochure is to educate users about strategies they can employ to save water and improve the performance of evaporative cooling systems. Principles of operation, a list of advantages and disadvantages, and a comparison of common systems is also included, to help users decide the best system for them.
Smith, Jason Berndt. "Sodium salt scaling in falling film black liquor evaporators." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/10263.
Повний текст джерелаBroome, Steven. "Liquid Distribution And Falling Film Wetting In Dairy Evaporators." Thesis, University of Canterbury. Department of Chemical and Process Engineering, 2005. http://hdl.handle.net/10092/4027.
Повний текст джерелаFarnham, Taylor A. "Design and fabrication of evaporators for thermo-adsorptive batteries." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92611.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 61).
Current heating and cooling within electric vehicles places a significant demand on the battery, greatly reducing their potential driving range. An Advanced Thermo- Adsorptive Battery (ATB) reduces this load by storing thermal energy within a bed of adsorptive sheets. A phase change heat exchanger capable of delivering the required cooling via liquid-vapor phase change was designed and prototyped for ATB. The thermal performance and fluid flow within the phase change heat exchanger were characterized for both coolant and refrigerant. A full-scale and quarter-length prototype was designed within the desired geometric and operating condition constraints. In order to build the phase change heat exchanger, fabrication techniques, including brazing, copper sintering, and bonding porous media were explored and characterized. In addition, the quarter-length design was fabricated and insights from its construction are proposed as recommendations for future work.
by Taylor A. Farnham.
S.B.
Sandström, Camilla. "Frosting and Defrosting on Air Source Heat Pump Evaporators." Thesis, KTH, Energiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299880.
Повний текст джерелаO'Halloran, Steven Patrick. "Experimental measurements and numerical analyses of an automotive evaporator /." Search for this dissertation online, 2006. http://wwwlib.umi.com/cr/ksu/main.
Повний текст джерелаDay, Benjamin Marc. "An Evaluation and Redesign of a Thermal Compression Evaporator." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/926.
Повний текст джерелаVan, den Dool Kari. "Evaporative cooling of apple and pear orchards." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1251.
Повний текст джерелаMusa, Mu'azu. "Novel evaporative cooling systems for building applications." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10674/.
Повний текст джерелаHudson, David Mark. "The high temperature evaporative refining of metals." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330210.
Повний текст джерелаHall, Carsie Alvin. "Evaporative cooling effects in precision machine tools." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36012.
Повний текст джерелаCiccone, Brianne N. "Modeling of Evaporative Losses in Industrial Pasteurization." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1339587036.
Повний текст джерелаSahu, Srikrishna. "Experimental study of isothermal and evaporative sprays." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7076.
Повний текст джерелаCaravello, Victor. "Total evaporative resistance of selected clothing ensembles." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000452.
Повний текст джерелаAgartan, Yigit Ata. "Experimental Comparison Of Different Minichannel Geometries For Use In Evaporators." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614095/index.pdf.
Повний текст джерелаBehbahani, Reza M. "Heat transfer and heat transfer fouling in phosphoric acid evaporators." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/842710/.
Повний текст джерелаЗубков, О. В., І. В. Свид, and О. С. Мальцев. "Features of the use of PID controllers when controlling evaporators." Thesis, MC&FPGA, 2020. https://mcfpga.nure.ua/conf/2020-mcfpga/10-35598-mcfpga-2020-001.
Повний текст джерелаElliott, Matthew Stuart. "Decentralized model predictive control of a multiple evaporator HVAC system." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3001.
Повний текст джерелаBérubé, Pierre. "High temperature biological treatment of foul evaporator condensate for reuse." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0028/NQ48606.pdf.
Повний текст джерелаChaer, Issa Namr. "Refrigeration performance with electrically enhanced heat transfer at the evaporator." Thesis, London South Bank University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313001.
Повний текст джерелаPRUZAESKY, FRANK CHAVIANO. "THEORETICAL AND EXPERIMENTAL STUDY OF A SHELL AND COIL EVAPORATOR." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2001. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1770@1.
Повний текст джерелаO presente trabalho diz respeito ao desenvolvimento de um modelo de simulação para evaporadores do tipo casco e serpentina, com aplicações para resfriadores de água. O modelo considera o trocador de calor como divido em duas zonas: uma de evaporação e outra de superaquecimento. Diferentes mecanismos de transferência de calor, existentes em cada zona, foram, portanto, levados em consideração. Definidas as condições de entrada de ambos os fluidos e a geometria do evaporador,um programa escrito em FORTRAN foi desenvolvido para calcular o desempenho térmico do evaporador, incluindo a capacidade térmica, condições de saída do refrigerante e água e distribuição de área de troca pelas duas zonas. Propriedades do refrigerantes foram calculadas com subrotinas do pacote REFPROP, desenvolvido no NIST, EUA, permitindo a modelagem de equipamentos operando com uma vasta gama de refrigerantes, incluindo hidrocarbonetos e misturas não azeotrópicas. Em virtude da ausência de informação na literatura, um aparato experimental foi construído para a determinação do coeficiente de transferência de calor no lado da carcaça, por onde escoa a água.
The present work is concerned with the development of a simulation model for shell and coil heat exchangers with first application in water-chillers. The model considers the heat exchanger as divided into two zones: two-phase region (boiling) and superheating region. Different refrigerant properties and heat transfer mechanisms are thus taken into account for each zone. For prescribed heat exchanger's geometry and water and efrigerant inlet conditions, a program in FORTRAN calculates the evaporator's performance which includes: refrigerant and water outlet conditions, evaporator's thermal capacity, and tube distribution for each zone. The REFPROP code programmed in FORTRAN was used for getting the local refrigerant properties, and the new kattan et al. s model for refrigerants boiling, including the new flow pattern map, was used for predicting the internal convective coefficient of heat transfer at the boiling region. A simple correlation was obtained for predicting the water convective coefficient depending on Reynolds number for the specific geometry at tested ranges of temperature. An evaporator was manufactured and an accurate test rig that included two controlled temperature baths and a data acquisition system was used for obtaining used data. The model is able to deal with a number of pure refrigerants and refrigerant blends.
El presente trabajo discute el desarrollo de un modelo de simulación para evaporadores de tipo casco y serpentina, con aplicaciones para refrigeradores de agua. El modelo considera que el agente de intercambio de calor está divido en dos zonas: una de evaporación y otra de supercalentamiento. Por esto, se consideraron los diferentes mecanismos de transferencia de calor existentes en cada zona. Definidas las condiciones de entrada de ambos fluidos y la geometría del evaporador, se desarrolló un programa en FORTRAN para calcular el desempeño térmico del evaporador, incluyendo la capacidad térmica, condiciones de salida del refrigerante y agua y distribución de área de intercambio térmico por las dos zonas. Las popriedades del refrigerante fueron calculadas con subrutinas del paquete REFPROP, desarrollado en el NIST, EUA, lo que permitió modelar los equipos operando con una vasta gama de refrigerantes, incluyendo hidrocarbonetos y mezclas no azeotrópicas. En virtud de la ausencia de información en la literatura, se construyó un aparato experimental para la determinación del coeficiente de transferencia de calor en el lado del casco, por donde sale el agua.
Hassan, Abdelrahman Hussein Abdelhalim. "Development and Validation of a Minichannel Evaporator Model under Dehumidification." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/71357.
Повний текст джерела[ES] En la primera parte de la tesis actual, dos modelos numéricos fundamentales (Fin2D-W y Fin1D-MB) para analizar el lado del aire de los evaporadores de minicanales se han desarrollado y verificado. El modelo Fin2D-W aplica un esquema detallado de dos dimensiones para discretizar el evaporador mientras que el modelo Fin1D-MB se basa en la teoría de la aleta unidimensional junto con la técnica de fronteras móviles para el lado del aire. El primer objetivo de los dos modelos presentados es identificar y cuantificar los fenómenos más influyentes encontrados en el proceso de enfriamiento y deshumidificación. El segundo objetivo es estudiar el impacto de las hipótesis comúnmente usadas en el modelado de la transmisión de calor del aire de los evaporadores de minicanales. Se implementaron diferentes estudios comparativos entre el enfoque tradicional Effectiveness-NTU y los modelos numéricos propuestos para alcanzar los objetivos mencionados. Los resultados muestran que las hipótesis que provocan una mayor desviación con respecto a la solución detallada en la transferencia de calor y masa son: propiedades de aire uniforme a lo largo de la altura de la aleta, extremo adiabático de aleta a mitad de su longitud, y no contemplar el supuesto de deshumidificación parcial en la aleta. Estas hipótesis ampliamente utilizadas han resultado en errores importantes en la transferencia de calor total, hasta un 52%, entre el enfoque Effectiveness-NTU y el modelo Fin2D-W. En la segunda parte de la tesis, el modelo Fin1D-MB se integró en la herramienta de simulación IMST-ART® para evaluar el rendimiento global de los evaporadores de minicanales (en el lado del aire y del refrigerante). El modelo Fin1D-MB se seleccionó gracias a su simplicidad, velocidad de cálculo, y solución de una precisión razonable relativa al modelo Fin2D-W. Se realizó una validación del modelo completo Fin1D-MB con la ayuda de datos experimentales y modelos numéricos ya disponibles en la literatura. El modelo se ha validado para diferentes geometrías de intercambiadores de calor, refrigerantes y condiciones de funcionamiento. Los resultados han mostrado que para los evaporadores de minicanales funcionando con el refrigerante R134a, el modelo Fin1D-MB predice de manera correcta las temperaturas de entrada del refrigerante y de salida del aire, la capacidad de enfriamiento, y la caída de presión del lado de refrigerante dentro de las bandas de error de ±0.5 ºC, ±5%, y ±20%, respectivamente. Para el evaporador de minicanales con CO2 (R744) estudiado, el modelo estima la capacidad de refrigeración y la temperatura de salida del aire dentro de las bandas de error de ±10% y ±1.0 ºC, respectivamente. En cuanto a la caída de presión de CO2, el modelo Fin1D-MB generalmente predice a la baja los valores de la caída de presión en comparación con los datos experimentales, con una desviación máxima de 11 kPa.
[CAT] A la primera part de la tesi actual, dos models numèrics fonamentals (Fin2D-W i Fin1D-MB) per analitzar el costat de l'aire dels evaporadors de minicanals s'han desenvolupat i verificat. Al model Fin2D-W s'aplica un esquema detallat de dues dimensions per discretitzar l'evaporador mentre que al model Fin1D-MB es basa en la teoria d'aleta unidimensional juntament amb la tècnica de frontera mòbil per al costat de l'aire. El primer objectiu dels dos models presentats és identificar i quantificar els fenòmens més influents trobats en el procés de refredament i deshumidificació. El segon objectiu és estudiar l'impacte de les hipòtesis comunament utilitzades en el modelatge de la transmissió de calor de l'aire dels evaporadors de minicanals. Es van implementar diferents estudis comparatius entre l'enfocament tradicional Effectiveness-NTU i els models numèrics proposats per assolir els objectius esmentats. Els resultats mostren que les hipòtesis que provoquen una major desviació respecte a la solució detallada a la transferència de calor i massa són: propietats d'aire uniforme al llarg de l'altura de l'aleta, extrem adiabàtic d'aleta a la meitat de la seua longitud, i no contemplar el supòsit de deshumidificació parcial en l'aleta. Aquestes hipòtesis àmpliament utilitzades donen errors importants en la transferència de calor total, fins a un 52%, entre l'enfocament Effectiveness-NTU i el model Fin2D-W. A la segona part de la tesi, el model Fin1D-MB es va integrar en l'eina de simulació IMST-ART® per avaluar el rendiment global dels evaporadors de minicanals (al costat de l'aire i del refrigerant). El model Fin1D-MB es va seleccionar gràcies a la seva simplicitat, velocitat de càlcul, i solució d'una precisió raonable relativa al model Fin2D-W. Es va realitzar una validació del model complet Fin1D-MB amb l'ajuda de dades experimentals i models numèrics ja disponibles a la literatura. El model s'ha validat per a diferents geometries d'intercanviadors de calor, refrigerants i condicions de funcionament. Els resultats mostren que per als evaporadors de minicanals funcionant amb el refrigerant R134a, el model Fin1D-MB prediu de manera correcta les temperatures d'entrada del refrigerant i de sortida de l'aire, la capacitat de refreda-ment, i la caiguda de pressió del costat de refrigerant dins de les bandes d'error de ±0.5 ºC, ±5%, i ±20%, respectivament. Per a l'evaporador de minicanals amb CO2 (R744) estudiat, el model estima la capacitat de refrigeració i la temperatura de sortida de l'aire dins de les bandes d'error de ±10% i ±1.0 ºC, respectivament. Pel que fa a la caiguda de pressió de CO2, el model Fin1D-MB generalment prediu a la baixa els valors de la caiguda de pressió en comparació amb les dades experimentals, amb una desviació màxima d'11 kPa.
Hassan, AHA. (2016). Development and Validation of a Minichannel Evaporator Model under Dehumidification [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/71357
TESIS
Yang, Jianxin. "A study of heat pump fin staged evaporators under frosting conditions." [College Station, Tex. : Texas A&M University, 2004. http://hdl.handle.net/1969.1/555.
Повний текст джерела"Major Subject: Mechanical Engineering" Title from author supplied metadata (record created on Jul. 18, 2005.) Vita. Abstract. Includes bibliographical references.
Kriesi, Ruedi. "Critical operation parameters of solar multi-stage evaporators with self regulation /." Lausanne, 1985. http://library.epfl.ch/theses/?nr=461.
Повний текст джерелаSOTOMAYOR, PAUL ORTEGA. "MODELING OF EVAPORATORS TYPE LAMINATED PLATE FOR AUTOMOTIVE AIR CONDITIONING SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12431@1.
Повний текст джерелаÉ desenvolvido um modelo de simulação de evaporadores automotivos tipo placa (Brazed Laminated Plate), para o resfriamento de ar úmido. O modelo estudado adota o método de análise local, onde o trocador de calor é dividido em um número de elementos de troca de calor, para os quais as equações de troca de calor e de conservação de energia são aplicadas. Para efeito da determinação do coeficiente local de troca de calor e do fator de atrito, o modelo considera duas regiões na troca de calor. Pelo lado do refrigerante foi considerada uma região bifásica (líquido - vapor) e outra, de superaquecimento (vapor). No lado do ar têm-se duas condições: com a superfície do evaporador seca ou molhada. Para cada zona foram levados em conta diferentes mecanismos de transferência de calor. Também foi estudada a queda de pressão do lado do refrigerante e do lado do ar, utilizando, para tal, as respectivas correlações de queda de pressão. Para a simulação foram consideradas definidas as condições de entrada dos fluídos e a geometria do evaporador. Um programa foi desenvolvido em FORTRAN para calcular os estados termodinâmicos de saída dos dois fluidos. As propriedades do refrigerante foram calculadas utilizando o software REFPROP versão 7.0, desenvolvido no NIST, EUA, o que permitiu a modelagem do trocador de calor operando com uma vasta gama de refrigerantes. Novos refrigerantes, H e 1234yf, ainda não constantes da biblioteca REFPROP v07, foram também testados. Os resultados da simulação foram comparados com dados experimentais disponíveis.
A simulation model for automotive brazed laminate plate evaporators, for humid air cooling, was developed. The model adopts the local analysis method, where the heat exchanger is divided into a number of elemental control volumes, for which the equations of heat transfer and conservation of energy are applied. In order to determine the local heat transfer coefficient and friction factor, the model considers different regions in the heat exchanger. In the refrigerant side, two-phase or superheated flows were considered. In the air side, dry or wet surface conditions were modeled. For each zone different mechanisms of heat transfer and pressure drop were taken in account. The simulation model assumed prescribed evaporator geometry and inlet conditions for both fluids. A computer program was developed in FORTRAN to calculate overall thermodynamic outlet states of both fluids. Refrigerant properties were calculated using the software REFPROP version 7.0, developed by the NIST, U.S.A.. It allowed the modeling of the evaporator, operating with a vast range of refrigerants. New refrigerants, fluids H and 1234yf, (still not available in REFPROP v07 libraries) also were tested. The results of the simulation were compared with available experimental data.
ZANETTI, EMANUELE. "EXPERIMENTAL AND NUMERICAL STUDY OF EVAPORATORS FOR MULTI-SOURCE HEAT PUMPS." Doctoral thesis, Università degli studi di Padova, 2022. https://hdl.handle.net/11577/3460845.
Повний текст джерелаThe present thesis aims at describing the operation of innovative evaporators employed in multi-source heat pumps. The exploitation of multiple sources at the low-pressure side of a heat pump is recently considered to be a good solution to air source heat pumps, whose performance is limited to the external air temperature and to the necessity of periodic defrosting cycles. In order to study the advantage of using multi-source heat pumps, it is necessary to investigate the performance of the selected evaporators at the desired operative conditions: to accomplish this purpose, the results of both experimental activities and simulations realized with ad hoc developed numerical tools are presented in this work. First, a 16 kW air/ground dual-source heat pump working with R32 for heating, cooling and DHW production has been experimentally characterized. The advantage of such configuration is that it is possible to extract or dissipate heat with the most convenient thermal source and the possibility to undersize the ground loop compared to a conventional ground-coupled system. In the framework of this activity, a novel minichannels air-to-refrigerant heat exchanger has been mounted on the heat pump and used as the evaporator. A 5 kW air/solar dual-source heat pump for water heating has also been experimentally studied in this work. When operating in solar-assisted mode, the evaporator consists of three PV-T (photovoltaic-thermal) solar collectors connected in parallel, where the refrigerant (CO2) is directly sent after the throttling process. The main advantage of using a solar evaporator is that, since the solar radiation can be considered as a forced heat flux, the evaporation temperature can be higher than that obtained in an air-to-refrigerant heat exchanger when the solar irradiance is high. Furthermore, the use of a PV-T device can reduce the global power consumption, due to PV electricity production. The presented heat pump prototype has been also designed to work in an innovative flooded-evaporation configuration: in this case, liquid CO2 enters the collectors and the flow is ensured by a natural circulation loop. The main advantage is the possibility to eliminate the maldistribution issues occurring in heat pump evaporators. All the heat exchangers used analyzed experimentally have been numerically modelled in this work. A model of a brazed plate heat exchange, of a conventional finned coil heat exchanger, of an air-to-refrigerant minichannels heat exchanger and of a PV-T evaporator have been realized. The models have been developed in Matlab environment, following a distributed parameters approach: each discretized element is treated as an independent heat exchanger where continuity, momentum and energy equations are solved; in this sense, a “physical” approach has been used. This managed to investigate the operation of the studied heat pumps in non-tested conditions to further optimize the design and functioning of their components. However, all the developed evaporators models are partly based on empirical correlations, in particular for the determination of the heat transfer coefficients on the refrigerant side. Empirical correlations are not always accurate and a well-established predictive model is not available in the literature. For this reason, a section of the present manuscript has been dedicated to presenting the description and the first results of a new CFD method for modelling the evaporation phenomenon in small channels during annular flow with refrigerants. The simulations have been realized in OpenFOAM environment and are based on the application of the Volume of Fluid method.
Gentine, Pierre. "Analysis of the diurnal behavior of Evaporative Fraction." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34605.
Повний текст джерелаIncludes bibliographical references (leaves 153-160).
In this thesis, the diurnal behavior of Evaporative Fraction (EF) was examined. EF was shown to exhibit a typical concave-up shape, with a minimum usually reached in the middle of the day. The influence of the vegetation cover and the soil moisture conditions on EF diurnal shape was also investigated. We also checked the repercussion of a change in environmental conditions on EF. This study will finally allow a better understanding of EF and suggests some new methods to obtain a good estimate of EF and of evapotranspiration.
by Pierre Gentine.
S.M.
Al-Shooshan, Ahmad A. "Nozzle type evaporative cooling system in the greenhouse." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291124029.
Повний текст джерелаSait, Hani. "Analytical and experimental study of thin film evaporation in heat pipes /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164540.
Повний текст джерела