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Relevant bibliographies by topics / Superheat

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Academic literature on the topic 'Superheat'

Author: Grafiati

Published: 4 June 2021

Last updated: 4 February 2022

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Journal articles on the topic "Superheat"

1

SIMÕES-MOREIRA, J. R., and J. E. SHEPHERD. "Evaporation waves in superheated dodecane." Journal of Fluid Mechanics 382 (March 10, 1999): 63–86. http://dx.doi.org/10.1017/s0022112098003796.

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We have observed propagating adiabatic evaporation waves in superheated liquid dodecane, C12H26. Experiments were performed with a rapid decompression apparatus at initial temperatures of 180–300°C. Saturated dodecane in a tube was suddenly depressurized by rupturing a diaphragm. Motion pictures and still photographic images, and pressure and temperature data were obtained during the evaporation event that followed depressurization. Usually, a front or wave of evaporation started at the liquid free surface and propagated into the undisturbed regions of the metastable liquid. The evaporation wave front moved with a steady mean velocity but the front itself was unstable and fluctuating in character. At low superheats, no waves were observed until a threshold superheat was exceeded. At moderate superheats, subsonic downstream states were observed. At higher superheats, the downstream flow was choked, corresponding to a Chapman–Jouguet condition. At the most extreme superheat tested, a vapour content of over 90% was estimated from the measured data, indicating a nearly complete evaporation wave. Our results are interpreted by modelling the evaporation wave as a discontinuity, or jump, between a superheated liquid state and a two-phase liquid–vapour downstream state. Reasonable agreement is found between the model and observations; however, there is a fundamental indeterminacy that prevents the prediction of the observed wave speeds.

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Chellaiah, S., and R. Viskanta. "Freezing of Water-Saturated Porous Media in the Presence of Natural Convection: Experiments and Analysis." Journal of Heat Transfer 111, no. 2 (May 1, 1989): 425–32. http://dx.doi.org/10.1115/1.3250694.

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Freezing of superheated water-porous media (glass beads) contained in a rectangular test cell has been studied both experimentally and numerically. The effects of liquid superheat and imposed temperature difference were investigated. When the superheat across the liquid region was small the flow in the porous media was weak, and the interface was almost planar. For larger superheats, natural convection flow and the solidification front shape and velocity were found to depend on the imposed temperature and the permeability of the porous medium. Due to the density inversion of water, the rate of freezing was higher, either at the top or at the bottom of the cell, depending on the amount of superheat. The measured temperature distributions were compared with predictions of numerical model that considered both conduction in the solid and natural convection in the liquid region. This model is based on volumetric averaging of the macroscopic transport equations, with phase change assumed to occur volumetrically over a small temperature range. Both Brinkman and Forchheimer extensions were added to the Darcy equations. The effect of density inversion of water on the fluid flow and heat transfer has been modeled. Good agreement has been found between the experimental data and numerical predictions.

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Zheng, Qiang, Hui Qing Liu, Zhan Xi Pang, and Fang Li. "A Study on Effect Evaluating and Parameters Sensitivity Analyzing of Superheated Steam Soak in Heavy Oil Reservoirs." Advanced Materials Research 239-242 (May 2011): 3069–73. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.3069.

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By using the technology of numerical reservoir simulation, we have compared superheated steam soak with saturated steam soak in area of heating, effect of distillation, capability of increasing oil production, volume of steam in need to evaluate the effect of superheated steam soak in heavy oil reservoirs. Analyzed the sensitivity of parameters like steam injection intensity, steam injection rate, soak time, degree of superheat to conclude the rule that they affect on recovery percentage. The research shows that, heating radius of superheated steam is greater than that of saturated steam, distillation effect of superheated steam is better than that of saturated steam, oil production of superheated steam is more than that of saturated steam, steam volume in need of superheated steam is less than that of saturated steam. Recovery percentage of superheated steam soak increases but more and more slowly with the increase in steam injection intensity, increases first and then decreases with the increase in steam injection rate, increases first and then decreases with the increase in soak time, increases but more and more slowly with the increase in degree of superheat. Influence of steam injection intensity is obvious to recovery percentage, but influence of other factors like soak time, steam injection rate, degree of superheat is insignificant.

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4

He, Congge, Anzhu Xu, Zifei Fan, Lun Zhao, and Bing Bo. "A New Mathematical Model For Heat Radius of Cyclic Superheated Steam Stimulation with Horizontal Wellbore." Mathematical Problems in Engineering 2018 (May 31, 2018): 1–11. http://dx.doi.org/10.1155/2018/7601702.

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When superheated steam flows along the horizontal wellbore, it may change to saturated steam at some point of the wellbore. In this paper, to accurately predict the heat radius of cyclic superheated steam stimulation with horizontal wellbore, the distribution of thermophysical properties of superheated steam along the horizontal wellbore is considered. The heating process is divided into 4 stages for superheated steam and 3 stages for saturated steam when the phase change undergoes in the wellbore. On this basis, the mathematical model for heat radius of cyclic superheated steam stimulation with horizontal wellbore was established according to energy conservation principle and Laplace transformation method. The calculation result of the new mathematical model is in good agreement with that of the numerical simulation (CMG STARS) for the same parameters from a specific heavy oil reservoir, which verified the correctness of the new mathematical model. The effect of degree of superheat and the cycle of stimulation are analyzed in detail after the new mathematical model is validated. The results show that the heat radius of superheated zone, steam zone, and hot fluid zone all decrease with horizontal well length and increase with the cycle of stimulation. The higher the degree of superheat is, the farther from the heel of the horizontal wellbore the phase change undergoes. Besides, the radius of superheated zone, steam zone, and hot fluid zone increases with the degree of superheat, but the value increases little at steam zone and hot fluid zone.

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Basu, Nilanjana, Gopinath R. Warrier, and Vijay K. Dhir. "Wall Heat Flux Partitioning During Subcooled Flow Boiling: Part 1—Model Development." Journal of Heat Transfer 127, no. 2 (February 1, 2005): 131–40. http://dx.doi.org/10.1115/1.1842784.

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In this work a mechanistic model has been developed for the wall heat flux partitioning during subcooled flow boiling. The premise of the proposed model is that the entire energy from the wall is first transferred to the superheated liquid layer adjacent to the wall. A fraction of this energy is then utilized for vapor generation, while the rest of the energy is utilized for sensible heating of the bulk liquid. The contribution of each of the mechanisms for transfer of heat to the liquid—forced convection and transient conduction, as well as the energy transport associated with vapor generation has been quantified in terms of nucleation site densities, bubble departure and lift-off diameters, bubble release frequency, flow parameters like velocity, inlet subcooling, wall superheat, and fluid and surface properties including system pressure. To support the model development, subcooled flow boiling experiments were conducted at pressures of 1.03–3.2 bar for a wide range of mass fluxes 124-926kg/m2 s, heat fluxes 2.5-90W/cm2 and for contact angles varying from 30° to 90°. The model developed shows that the transient conduction component can become the dominant mode of heat transfer at very high superheats and, hence, velocity does not have much effect at high superheats. This is particularly true when boiling approaches fully developed nucleate boiling. Also, the model developed allows prediction of the wall superheat as a function of the applied heat flux or axial distance along the flow direction.

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Chen, Tailian, and Jacob N. Chung. "An Experimental Study of Miniature-Scale Pool Boiling." Journal of Heat Transfer 125, no. 6 (November 19, 2003): 1074–86. http://dx.doi.org/10.1115/1.1603773.

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By generating single bubbles on a micro-heater at different wall superheats, an experimental study of miniature-scale pool boiling heat transfer has been performed to provide a fundamental understanding of the heater size effect. In this study, the constant-temperature microheater is set at different temperatures by an electronic feedback control system. The heat transfer history during the lifetime of a single bubble which includes nucleation, growth, detachment and departure has been measured. The boiling curve obtained from the microheater is composed of two regimes which are separated by a peak heat flux. It is suggested that in the lower superheat regime, the boiling is dominated by liquid rewetting and micro-layer evaporation, while in the higher superheat regime, conduction through the vapor film and micro-convection plays the key heat transfer role as the heater is covered by vapor all the time. In general, boiling on microheaters is characterized by larger bubble departure sizes, smaller bubble growth rates due to the dryout of microlayer as the bubble grows, and higher bubble incipience superheat. As the heater size decreases, the boiling curve shifts towards higher heat fluxes with corresponding higher superheats.

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7

Ramesh, Arumugam, and Ramasamy Balasubramanian. "Ability of the generalized van der Waals and Berthelot equations of state to determine the thermodynamic stability of liquid lead." Science Vision 20, no. 4 (December 31, 2020): 132–38. http://dx.doi.org/10.33493/scivis.20.04.01.

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The known van der Waals and Berthelot equations of state do-not precisely describe the thermodynamic properties of fluids. To improve its accuracy, the attractive term of the van der Waals equation of state has been modified in six different ways. These generalized equations of state have been employed to determine the spinodal (thermodynamic stability boundary) and the thermodynamic limit of superheat of liquid lead. The equations of state are rewritten in reduced form, from which follows the law of corresponding states. The appropriate modification of the attractive term of the equation of state yielding the value of thermodynamic limit of superheat agreeing with the experimental value for lead has been established. It has been established that liquid lead can be superheated, under rapid heating, up to a temperature 4565 K. That is, liquid lead can be superheated to 2544 K above the normal boiling temperature. At the thermodynamic limit of superheat, the volume of the liquid lead is 4.0095 × 10-5 m3 mol-1. This fact is to be taken into account when liquid lead is subjected to rapid heating.

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Ramos, R. A., and J. Castro. "A REVIEW OF THE EFFECTS OF CHANGES IN THE VOID FRACTION OF THE SUPERHEATED REGION ON THE TEV OPERATION AND EVAPORATOR STABILITY." Revista de Engenharia Térmica 15, no. 2 (December 31, 2016): 38. http://dx.doi.org/10.5380/reterm.v15i2.62175.

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A level of superheat is necessary to ensure proper operation of vapor- compression refrigeration systems. An overly superheated vapor prior to entering the compressor can render the system inefficient, while inadequate superheat can result in evaporator instability and compressor damage. The void fraction present in the suction line is directly related to evaporator stability and the hunting phenomenon in the thermostatic expansion valve (TEV). This article aims at reviewing superheated region-related researches in the field of refrigeration as they relate to the operation of the TEV and the stability of the evaporator. In a first part, literature review will explain the causes of the void fraction in the superheated region and the second part describes the effects of the lubricant oil on the void fraction. The third part of this article is a review of the effects of the superheated region on the TEV and on evaporator stability, explaining the causes of the hunting phenomena and evaporator instability.

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Reyes, R., and P. C. Wayner. "A Kelvin–Clapeyron Adsorption Model for Spreading on a Heated Plate." Journal of Heat Transfer 118, no. 4 (November 1, 1996): 822–30. http://dx.doi.org/10.1115/1.2822576.

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A new adsorption model for the spreading dynamics of completely wetting fluids on a heated solid substrate that emphasizes interfacial phenomena is developed and evaluated. The model is based on the premise that both interfacial intermolecular forces and temperature affect the vapor pressure in change-of-phase heat transfer and (therefore) the spreading velocity. Classical change-of-phase kinetics, and interfacial concepts like the Clapeyron, Kelvin, and the augmented Young–Laplace equations are used to evaluate the effects of stress (change in apparent dynamic contact angle), temperature, and superheat on the rewetting velocity. Explicit equations are obtained for the velocity, heat flux, and superheat in the contact line region as a function of the initial plate temperature. Comparisons with experimental data for substrate superheats below a critical value demonstrate that the resulting interfacial model of evaporation/condensation in the contact line region can describe the effect of the saturation temperature and superheat on the rewetting velocity.

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10

Ravichandar, D., Thangavel Balusamy, and K. Bommannan Nagashanmugam. "Reducing UT Rejections in Cr-Mo and High Mn Steels by Controlling Hydrogen and Optimising Superheat." Applied Mechanics and Materials 591 (July 2014): 38–42. http://dx.doi.org/10.4028/www.scientific.net/amm.591.38.

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JSW Steel Limited, Salem Works (JSWSL), is an integrated steel plant, having a production capacity of 1.0 mtpa (million tons per annum) of high-grade automotive special steels. At JSWSL, hydrogen induced cracks and center unsoundness contribute more to UT (Ultrasonic testing) rejections in chrome-molybdenum (Cr-Mo) and high manganese grade steels. Hydrogen induced cracks was controlled by increasing argon flow rate from 3-4 Nm3 to 7-9 Nm3 during vacuum degassing. Vigorous purging led to a reduction in hydrogen levels from around 2 ppm (parts per million) to less than 1.5 ppm. Center unsoundness was controlled through optimising superheats in tundish. Data of trial heats revealed that, UT rejections were more in heats cast with superheat levels more than 35°C. Based on the data obtained from trial heats superheat was optimised to 25-35°C for both Cr-Mo and high manganese steels. The present paper discusses the measures taken to reduce UT rejections in these grades.KeywordsJSWSL, Cr-Mo, High Mn steels, UT rejections, superheat, hydrogen induced cracks, center unsoundness, vacuum degassing, continuous casting.

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Dissertations / Theses on the topic "Superheat"

1

Newman, Aaron W. "The effect of superheat on liquid droplets in a supersonic freestream." Link to electronic version, 1999. http://www.wpi.edu/Pubs/ETD/Available/etd-051199-174419/unrestricted/thesis.pdf.

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Ko, Yu-Chih Ph D. Massachusetts Institute of Technology. "Conceptual design of an annular-fueled superheat boiling water reactor." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/76976.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, February 2011.
"September 2010." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 219-225).
The conceptual design of an annular-fueled superheat boiling water reactor (ASBWR) is outlined. The proposed design, ASBWR, combines the boiler and superheater regions into one fuel assembly. This ensures good neutron moderation throughout the reactor core. A single fuel design is used in the core. Each annular fuel element, or fuel tube, is cooled externally by boiling water and internally by steam. Fuel pellets are made of low enrichment U0 2, somewhat higher than the traditional BWR fuel enrichment. T91 and Inconel 718 are selected as candidates for the cladding material in view of their excellent physical properties and corrosion resistance. The fuel-cladding gap is filled with pressurized helium gas, like the existing lighter water reactor fuels. The ASBWR fuel assembly contains sixty annular fuel elements and one square water rod (occupying a space of four fuel elements) in an 8 by 8 square array. Annular separators and steam dryers are utilized and located above the core in the reactor vessel. Reactor internal pumps are used to adjust the core flow rate. Cruciform control rods are used to control the reactivity of the core, but more of them may be needed than a traditional BWR in view of the harder spectrum. The major design constraints have been identified and evaluated in this work. The ASBWR is found promising to achieve a power density of 50 kW/L and meet all the main safety requirements. This includes a limit on the minimum critical heat flux ratio, maximum fuel and cladding operating temperatures, and appropriate stability margin against density wave oscillations. At the expected superheated steam of 520 °C, the plant efficiency is above 40%, which is substantially greater than the efficiency of 33 to 35% that today's generation of LWRs can achieve. In addition to generating electricity, the ASBWR may also be useful for liquid fuel production or other applications that require high temperature superheated steam. The uncertainties about this design include the performance of cladding materials under irradiation, the attainment of desirable heat transfer ratio between the external and internal coolant channels throughout the fuel cycle, and the response to the traditional transients prescribed as design basis events.
by Yu-Chih Ko.
Ph.D.

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3

Yanson, Logan M. "Effects of Liquid Superheat on Droplet Disruption in a Supersonic Stream." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-042905-151247/.

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4

Dhungana, Navaraj. "Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment." Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2188.

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The Project in Canada to Search for Supersymmetric Objects (PICASSO) searches for cold dark matter through the direct detection of Weakly Interacting Massive Particles (WIMPs) via spin-dependent and spin independent interactions with 19F nuclei. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. In order to reduce the background, it is essential to distinguish the signature of different background particles interacting in the detector. A dedicated setup was developed in order to study the response of the C4F10 droplets in the presence of different backgrounds. The main objectives of this research are to identify the actual size (diameter) of the droplet increases due to phase transition and to check and establish the correlation between the droplet size and the maximum amplitude of the signal. In addition, the alpha-neutron discrimination was studied by observing each event’s image frames and the associated acoustic signal to get the amplitude distribution. The mean ratio of bubble size to droplet size was found to be 5.48, independent of temperature and type of interacting particle. Furthermore, no correlation was found between the droplet size and the maximum amplitude of the signal. As for the discrimination studies, the analysis of the signal events has confirmed that alphas generated outside the active liquid in the gel are much more difficult to discriminate from neutron than when alphas are generated inside the active liquid.

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5

Hervás, Blasco Estefanía. "Aprovechamiento del calor residual a baja temperatura mediante bombas de calor para la producción de agua caliente." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/137776.

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[ES] Un porcentaje significativo de la energía se destina a la producción de Agua Caliente Sanitaria (ACS) en el sector comercial y residencial. Además, la mayor parte de la energía que contiene el agua se desperdicia en el ambiente tras su uso. Las bombas de calor han sido identificadas por su capacidad de producir ACS con una alta eficiencia y son una gran alternativa hacia la descarbonización de las ciudades. Además, son capaces de utilizar como fuente de calor, el calor contenido en el agua que actualmente se desperdicia. Sin embargo, la aplicación del uso de bombas de calor para ACS recuperando el calor de las aguas residuales presenta unas características diferentes a las usuales en bombas de calor. Por tanto, es necesario un análisis del problema más profundo y se require mayor investigación al respecto con el fin de lograr un desarrollo eficiente de la misma: 1. Un diseño de bomba de calor capaz de operar con alta eficiencia ante los grandes saltos de temperatura que tienen lugar en esta aplicación (ACS). 2. Un diseño de bomba de calor capaz de operar con alta eficiencia ante saltos de temperatura del fluido secundario variables (recuperación de calor). 3. La integración de esta bomba de calor en un sistema de ACS completo (estrategias de recuperación de calor, componentes, tamaño y estrategia de control). Normalmente, los ciclos transcríticos han sido considerados como una de las mejores soluciones para la producción de ACS (donde se tienen grandes saltos de temperatura en el agua, 10-60°C). Sin embargo, este tipo de ciclo presenta dos desventajas principales, la necesidad de altas presiones en la instalación y la dependencia de la eficiencia con el salto de temperatura del agua en el condensador. Sin embargo, los ciclos subcríticos han demostrado un gran potencial para saltos de temperatura del agua variables si se aplica un control del subenfriamiento adecuado. El objetivo de esta tesis es investigar la bomba de calor agua-agua más eficiente trabajando con un ciclo de refrigerante subcrítico para la producción de ACS utilizando como fuente de calor el calor disponible en las aguas residuales (a baja-media temperatura) para determinar el sistema más eficiente para este tipo de aplicación. El trabajo se divide en dos partes diferenciadas: ¿ Diseño de la bomba de calor El desarrollo de la bomba de calor es una continuación del trabajo realizado en la tesis de M. Pitarch [1]. En dicha tesis, se investigó el papel del subenfriamiento en una bomba de calor subcrítica para la apliación de ACS. Se desarrolló un prototipo de bomba de calor con el diseño de dos configuraciones distintas en función del modo en el que se realizaba el subenfriamiento. Los resultados permitieron concluir que este tipo de bombas de calor (subcríticas) eran capaces de operar con eficiencias similares a las de las bombas de calor basadas en ciclos transcríticos si se opera con un grado de subenfriamiento óptimo. Sin embargo, en ambas configuraciones se requiere un componente más que en las bombas de calor convencionales. En esta tesis, se ha realizado un estudio y análisis teórico de la bomba de calor. Se ha desarrollado e implementado una estrategia de control para el subenfriamiento y se ha construído el prototipo de bomba de calor propuesto en [1]. De todo este trabajo se ha obtenido el diseño de bomba de calor basada en ciclos subcríticos más interesante para este tipo de aplicaciones. ¿ Diseño e integración de la Bomba de Calor y el sistema de ACS La integración del prototipo seleccionado en un sistema para la producción de ACS con recuperación del calor de las aguas residuales ha sido analizada.El sistema más simple y eficiente necesario para este tipo de aplicaciones (producción de ACS con recuperación de calor de las aguas grises) se compone de un intercambiador de calor (recuperador), una bomba de calor con subenfriamiento optimizado y dos depósitos de almacenamiento.
[CAT] Un percentatge significatiu de l'energia es destina a la producció d'Aigua Calenta Sanitària (ACS) en el sector comercial i residencial. A més, la major part de l'energia que conté l'aigua es malgasta en l'ambient després del seu ús. Les bombes de calor han sigut identificades per la seua capacitat de produir ACS amb una alta eficiència i són una gran alternativa cap a la descarbonització de les ciutats. A més, són capaços d'utilitzar com a font de calor, el calor contingut en l'aigua que actualment es desaprofita. Contribuint així, a aconseguir un sector energètic més respectuós amb el Medi Ambient. No obstant això, l'aplicació de l'ús de bombes de calor per a ACS recuperant el calor de les aigües residuals presenta unes característiques diferents de les usuals en bombes de calor. Per tant, és necessari una anàlisi del problema més profund i es requereix una major investigació al respecte amb la finalitat d'aconseguir una alta eficiència: 1.Un disseny de bomba de calor capaç d'operar amb alta eficiència davant dels grans salts de temperatura presents en aquesta aplicació (ACS). 2.Un disseny de bomba de calor capaç d'operar amb alta eficiència davant de salts de temperatura del fluid secundari variables (recuperació de calor). 3.La integració d'aquesta bomba de calor en un sistema d'ACS complet (estratègies de recuperació de calor, components, grandària i estratègia de control). Normalment, els cicles transcrítics han sigut considerats com una de les millors solucions per a la producció d'ACS (on es tenen grans salts de temperatura en l'aigua, 10-60°C). No obstant això, aquest tipus de cicle presenta dos desavantatges principals, la necessitat d'altes pressions en la instal·lació i la dependència de l'eficiència amb el salt de temperatura de l'aigua en el condensador i evaporador. L'objectiu d'aquesta tesi és investigar la bomba de calor aigua-aigua més eficient treballant amb un cicle de refrigerant subcrític per a la producció d'ACS utilitzant com a font de calor el calor disponible en les aigües residuals (a baixa-mitja temperatura) per a determinar el sistema més eficient en aquest tipus d'aplicació. El treball es dividix en: ¿ Disseny de la bomba de calor El desenvolupament de la bomba de calor és una continuació del treball realitzat en la tesi de M. Pitarch [1]. En aquella tesi, es va investigar el paper del subrefredament en una bomba de calor subcrítica per a l'apliació d'ACS. Es va desenvolupar un prototip de bomba de calor amb el disseny de dues configuracions distintes en funció de la manera en què es realitzava el subrefredament. Els resultats van permetre concloure que aquests tipus de bombes de calor (subcrítiques) eren capaços d'operar amb eficiències semblants a les de les bombes de calor basades en cicles transcrítics si s'opera amb un grau de subrefredament òptim. No obstant això, en ambdues configuracions es requereix un component més que en les bombes de calor convencionals. En la present tesi, es va realitzar un estudi i anàlisi teòric de la bomba de calor. Es va desenvolupar i implementar una estratègia de control per al subrefredament i es va construir el prototip de bomba de calor proposat en [1]. De tot aquest treball s'ha obtingut el disseny de bomba de calor basada en cicles subcrítics més interessant per aquest tipus d'aplicacions. ¿Disseny i integració de la Bomba de Calor i el sistema d'ACS La integració del prototip seleccionat en un sistema per a la producció d'ACS amb recuperació de el calor de el calor de les aigües residuals ha sigut analitzada.El sistema més simple i eficient necessari per a aquest tipus d'aplicacions (producció d'ACS amb recuperació de calor provinent d'aigües grisas) està compost per un bescanviador de calor (recuperador), una bomba subrefredada i dos depòsits d'emmagatzemament.
[EN] A significant percentage of energy is destined to produce Domestic Hot Water (DHW) within the building sector. Furthermore, most of that energy contained in the water is wasted to the ambient after its use. Heat pumps have been clearly identified as an efficient technology for DHW production, and as a main vector towards future de-carbonization of cities. In addition, they could use the heat from the wastewater as a heat source. Thus, contributing in two ways towards a more environmentally friendly energetic sector. However, the use of heat pumps for DHW recovering heat from wastewater faces several challenges that require further analysis and development: 1. A heat pump design capable to operate with high performance when variable secondary temperature lifts at the heat sink take place. 2. A heat pump design capable to operate with high performance when variable secondary temperature lifts at the heat source take place. 3. The integration of the heat pump within a system (heat recovery strategies, components, sizing, operation strategy). Usually, transcritical cycles have been considered the most suitable cycle for DHW production (high temperature lifts of the heat sink, 10-60°C). However, this cycle involves several drawbacks as for instance the requirement of high pressures in the installation or a significant reduction of the performance with the increase of water inlet temperature at the condenser. Instead, subcritical cycles have demonstrated great potential for DHW applications if a proper control of subcooling is performed. The objective of this thesis is to investigate the most efficient water-to-water heat pump working with a subcritical cycle for DHW production using as a heat source wasted heat at medium-low temperature and to determine the most efficient system based on heat pumps for this application. The work is divided in two differentiated parts: ¿ Heat pump concept This development is a continuation from the PhD work of M. Pitarch [1]. In that PhD work, the role of the subcooling in the performance of a subcritical heat pump for DHW applications was investigated. Two different configurations of a heat pump prototype were designed based on the way subcooling was made. The results showed that a subcooling optimized subcritical heat pump was able to provide comparable performance than present HPs employing transcritical cycles. However, both configurations require one more component than usual heat pumps. Thus, a new prototype based only on the typical components (compressor, condenser, expansion valve and evaporator) was proposed as future work. In this thesis, a theoretic analysis of the heat pump was done. A subcooling control methodology was developed and tested. The proposed prototype in [1] has been built and characterized. From all the results, the most convenient heat pump design was obtained. ¿ Integral Heat pump-DHW system The integration of the most convenient heat pump prototype within a system for the DHW production based on heat recovery from wastewater has been analyzed. The research has included the development of a model of the entire system in Trnsys and the optimization of the main components of the system: their sizing and their operation with the objective of reaching the maximum global efficiency of the complete system. Due to the complexity of the problem, the analysis was performed in three main steps: first, a study of the direct heat exchange,second, an study focusing on the condenser side, that is, the consideration of an infinite heat source (large availability of sewage water for instance) and third, the focus was done on the evaporator side. That is, the optimization of the complete system in which a finite heat source is considered (grey waters collected from the building for instance). The simplest and most efficient system required in DHW production and heat recuperation from wastewater has been determined.
Esta tesis se enmarca dentro del proyecto “APROVECHAMIENTO DEL CALOR RESIDUAL A BAJA TEMPERATURA MEDIANTE BOMBAS DE CALOR PARA LA PRODUCCION DE AGUA CALIENTE” a través de una beca FPI del Ministerio de Economía y Competitividad.
Hervás Blasco, E. (2020). Aprovechamiento del calor residual a baja temperatura mediante bombas de calor para la producción de agua caliente [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/137776
TESIS

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Tambovtsev, Alexander. "Energieeinsparung in Kälteanlagen durch Kombination von thermostatischem Expansionsventil und innerem Wärmeübertrager." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1218482331656-43301.

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Die Erfindung der Kältemaschine macht es möglich, dass heute zu beliebiger Zeit Kälte in benötigter Menge und gewünschter Temperatur erzeugt werden kann. Aber für die Kälteerzeugung braucht man Antriebsenergie. Das Ziel dieser Doktorarbeit besteht darin, mit einer intelligenten Kombination von thermostatischem Expansionsventil (TEV) und innerem Wärmeübertrager (IWÜ) den Energieverbrauch von Kälteanlagen deutlich zu verringern, ohne dass dies zu einer Verschlechterung der Zuverlässigkeit oder wesentlichen Mehrkosten führt. Bis heute gelten die beiden bekannten Komponenten TEV und IWÜ als inkompatibel miteinander, weil die einfache Aneinanderreihung zu einem instabilen Regelverhalten führt. Nach detaillierter Analyse der Ursachen dieser Instabilität wird die Hypothese aufgestellt, dass durch eine absichtliche „Verschlechterung“ des IWÜ ein stabiler Arbeitsbereich gefunden werden kann. Bei dieser „Verschlechterung“ kann es sich z. B. um den Bypass eines Teils des Hochdruckstromes oder um eine Gleichstromanordnung der Ströme im Wärmeübertrager handeln. Diese Hypothese wurde primär durch Experimente, aber zusätzlich auch durch Simulationsrechnungen bestätigt. Dafür wurde ein Versuchsstand aufgebaut, mit welchem verschiedene Konfigurationen und Regelstrategien getestet wurden. Es wurde eine deutliche Verringerung des Energieverbrauchs gegenüber herkömmlichen Anordnungen erreicht.

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Tambovtsev, Alexander. "Energieeinsparung in Kälteanlagen durch Kombination von thermostatischem Expansionsventil und innerem Wärmeübertrager." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23656.

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Die Erfindung der Kältemaschine macht es möglich, dass heute zu beliebiger Zeit Kälte in benötigter Menge und gewünschter Temperatur erzeugt werden kann. Aber für die Kälteerzeugung braucht man Antriebsenergie. Das Ziel dieser Doktorarbeit besteht darin, mit einer intelligenten Kombination von thermostatischem Expansionsventil (TEV) und innerem Wärmeübertrager (IWÜ) den Energieverbrauch von Kälteanlagen deutlich zu verringern, ohne dass dies zu einer Verschlechterung der Zuverlässigkeit oder wesentlichen Mehrkosten führt. Bis heute gelten die beiden bekannten Komponenten TEV und IWÜ als inkompatibel miteinander, weil die einfache Aneinanderreihung zu einem instabilen Regelverhalten führt. Nach detaillierter Analyse der Ursachen dieser Instabilität wird die Hypothese aufgestellt, dass durch eine absichtliche „Verschlechterung“ des IWÜ ein stabiler Arbeitsbereich gefunden werden kann. Bei dieser „Verschlechterung“ kann es sich z. B. um den Bypass eines Teils des Hochdruckstromes oder um eine Gleichstromanordnung der Ströme im Wärmeübertrager handeln. Diese Hypothese wurde primär durch Experimente, aber zusätzlich auch durch Simulationsrechnungen bestätigt. Dafür wurde ein Versuchsstand aufgebaut, mit welchem verschiedene Konfigurationen und Regelstrategien getestet wurden. Es wurde eine deutliche Verringerung des Energieverbrauchs gegenüber herkömmlichen Anordnungen erreicht.

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Eyssette, Roland. "Caractérisation et modélisation des effets de surpression en champ proche et du chargement au sol du BLEVE." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEM020/document.

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Le BLEVE (Boiling Liquid Exploding Vapor Explosion) est l’un des accidents les plus craints dans l’industrie. Bien qu’il soit étudié depuis plus de soixante ans, certains dangers et situations restent mal anticipés, tels que : quelles seraient les conséquences de la surpression d’un BLEVE dans un milieu urbain confiné ? Qu’adviendrait-il si un camion de transport de GPL venait exploser sur un pont ? Ces questions nécessitent d’étudier la physique du BLEVE au plus proche du conteneur. Ce travail explore les phénomènes physiques générant la surpression aérienne en champ proche de l’explosion, en essayant de comprendre la contribution des phases du contenu (liquide et vapeur) dans les dangers en champ proche du BLEVE. Un prototype expérimental petite échelle a été conçu dans le but de reproduire les BLEVE de cuves cylindriques de manière réaliste. Vingt-quatre BLEVEs de propane ont été effectués. Un large spectre de données a été collecté lors de ces tests : surpression aérienne dans de multiples directions autour du conteneur, variations de pression dans le conteneur avant et après rupture, chargement au sol dû à l’explosion, visualisations en imagerie rapide selon un certain nombre d’angles. Les résultats montrent une dépendance forte entre les caractéristiques de la phase vapeur et la suppression maximale générée par l’explosion. La reconstruction chronologique du phénomène confirme ce résultat. Cependant, la phase liquide joue un rôle capital dans la génération du chargement au sol, qui est un danger considérable, mais peu considéré jusque-là
Boiling Liquid Exploding Vapor Explosion (BLEVE) is one of the most feared accident in the industry. Even though it has been studied for over 6 decades, many safety questions remain poorly answered: what happens if a BLEVE occurs in a congested urban or industrial area? What if a road tanker BLEVE happens on a bridge? These questions require to look closer to the vessel. This work focuses on understanding the physics involved in overpressure generation in the near field surrounding of the vessel, to understand the contribution of the fluid phases (liquid and vapor) in the near-field hazards of a BLEVE. For this purpose, a small scale experimental prototype was designed to reproduce realistic BLEVE failure. Twenty-four propane BLEVEs were performed. A wide range of data was recorded from these tests: blast overpressure all around the vessel, transient pressure inside the vessel, ground loading under the vessel, and high speed imaging through various angles. Results give more insight on the anisotropy of the pressure field around the cylindrical vessel. It also shows a strong dependency between vapor content and maximum overpressure from the lead shock. Moreover, the chronology of the phase change observed through transient pressure measurements show that the main contributor of the maximum overpressure is the vapor phase. The phase change is studied through pressure transient in the vessel and high speed imaging, giving a better understanding of the time scales involved with this phenomenon. Finally, ground loading measurements are analyzed to give insight on the order of magnitude involved in this hazard

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Tajuddin, Ruziyati. "Superheated water extraction (SWE) coupled on-line with superheated water chromatography (SWC)." Thesis, Loughborough University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403568.

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Antonelli, Anna Giulia. "An experimental study of water BLEVE." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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A BLEVE is a physical explosion characterized by the sudden expansion of a liquefied gas under pressure and the vapor space above it. In this work, the analysis of a set of water BLEVE experiments was carried out both in terms of data processing and numerical modelling. The main purpose of the project was to investigate safety implications of a pipe rupture containing superheated water that may affect a steam generation system in a nuclear or chemical plant. The experimental campaign consisted in 27 explosive tests in which an instantaneous depressurization of the content was enabled by the use of a calibrated rupture disk. A flange calibrated for different dimensions of the releasing orifice was incorporated in the prototype to replicate a pipe failure for various nominal sizes. The analysis primarily focused on the pressure field distribution generated in the surroundings, in the form of multiple shock waves. First observations came directly from high-speed pressure data recorded, showing a high directionality of the blast, stronger in the vertical direction, and the independence of the lead shock on the initial liquid fill level. The intensity of the overpressure of the lead shock was found to be increasingly correlated with the opening size. Available theoretical methods were used to preliminarily estimate the first overpressure peak. Models based on real gas behaviour and adiabatic irreversible expansion gave the best approximation of the vertical overpressure, providing an energy conversion factor (energy contributing to the blast overpressure over the total expansion energy) comparable with values found in the literature. A few CFD simulations were then performed under a shock tube configuration to validate the widely accepted assumption that the lead pressure peak is exclusively depending on the expansion of the pressurized vapor space.

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Books on the topic "Superheat"

1

Superhero. New York: Scholastic Press, 2005.

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Gansner, Hans Peter. Superherz. Wien: Songdog Verlag, 2014.

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Superhero silliness. New York: Egmont USA, 2012.

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Bissell, Tom. Superhero stories. Charlottesville, Va: Univ. of Virginia, 2008.

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Superhero School. New York: Bloomsbury Children's Books, 2009.

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McLeod, Bob. SuperHero ABC. New York: HarperCollins, 2006.

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Leavitt, Martine. Heck, superhero. Calgary: Red Deer Press, 2004.

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ill, Finger Matthew, ed. Superhero swamp. Nashville: Thomas Nelson, 2007.

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Bissell, Tom. Superhero stories. Charlottesville, Va: Univ. of Virginia, 2008.

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SuperHero ABC. New York: HarperCollins, 2006.

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Book chapters on the topic "Superheat"

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Vinogradov, V. E., and P. A. Pavlov. "Limiting Superheat of Aqueous Solutions at Negative Pressures." In Liquids Under Negative Pressure, 13–22. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0498-5_2.

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Zhao, Shiwei, Yongfang Xie, Weichao Yue, and Xiaofang Chen. "A Machine Learning Method for State Identification of Superheat Degree with Flame Interference." In 10th International Symposium on High-Temperature Metallurgical Processing, 199–208. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05955-2_19.

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Poole, Gregory, Nathan Rimkus, Aeriel Murphy, Paige Boehmcke, and Nagy El-Kaddah. "Effect of the Solidification Rate on Microstructure of Cast Mg Alloys at Low Superheat." In Magnesium Technology 2012, 161–64. Cham: Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-319-48203-3_30.

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Poole, Gregory, Nathan Rimkus, Aeriel Murphy, Paige Boehmcke, and Nagy El-Kaddah. "Effect of the Solidification Rate on Microstructure of Cast Mg Alloys at Low Superheat." In Magnesium Technology 2012, 161–64. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118359228.ch30.

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Vynnycky, Michael. "A Criterion for Air-Gap Formation in Vertical Continuous Casting: The Effect of Superheat." In Mathematics in Industry, 185–90. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05365-3_25.

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Nastac, Laurentiu, and Nagy El-Kaddah. "Computational Multi-Scale Modeling of the Microstructure and Segregation of Cast Mg Alloys at Low Superheat." In Magnesium Technology 2013, 263–70. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118663004.ch44.

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Xie, Jun, Songli Wang, Yuwei Wang, and Jianzhong He. "Research on Predictive Control of Evaporator Superheat System with Time-Delay Based on DMC Intelligent Optimization." In Advances in Intelligent Systems and Computing, 785–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-54927-4_74.

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Nastac, Laurentiu, and Nagy El-Kaddah. "Computational Multi-Scale Modeling of the Microstructure and Segregation of Cast Mg Alloys at Low Superheat." In Magnesium Technology 2013, 265–70. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-48150-0_44.

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Zhong, Honggang, Yi Tan, Huigai Li, Xinping Mao, and Qijie Zhai. "The Effect of High Superheat on the Solidification Structure and Carbon Segregation of Ferrite-Based Alloy." In Supplemental Proceedings, 215–21. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118356074.ch29.

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Mäkinen, Mika, and Markku Uoti. "The Effect of Superheat on Micro- and Macrosegregation and Crack Formation in the Continuous Casting of Low-Alloyed Copper." In Materials Science Forum, 549–54. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-991-1.549.

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Conference papers on the topic "Superheat"

1

Yabuki, Tomohide, and Osamu Nakabeppu. "Heat Transfer Characteristics of Isolated Bubble Nucleate Boiling of Water." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44519.

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The mechanism of isolated bubble pool nucleate boiling of water is studied by a novel approach method using the developed MEMS thermal sensor. The local temperature variation beneath isolated bubble was measured using the MEMS sensor at different six wall superheats. Evaporation and dry-out of the microlayer and the rewetting of the dry-out area were obviously observed in the measured temperature variation. Wall heat transfer was numerically calculated by transient heat conduction simulation with the measured temperature as a surface boundary condition. The results showed that the microlayer evaporation transfers high heat flux of a few MW/m2, and dominantly contributes to the heat transport from the heating wall during the bubble growth phase. The ratio of the heat transferred from the wall to the latent heat in the bubble at the departure decreased with increasing wall superheat. In other words, the contribution of the heat transfer from the superheated liquid layer surrounding the bubble becomes important with increasing wall superheat. Moreover, the microlayer thickness was calculated by integrating the local heat flux. The derived initial thickness of the microlayer was independent from the wall superheat and became thick as distance from the nucleation site increases.

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Adera, Solomon, Rishi Raj, Ryan Enright, and Evelyn N. Wang. "Evaporation-Induced Cassie Droplets on Superhydrophilic Microstructured Surfaces." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73224.

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A droplet deposited on a rough, lyophilic surface satisfying the imbibition condition, results in complete wetting. However, in this work, we demonstrate that this behavior can be altered by superheating the substrate such that droplets can reside in a non-wetting Cassie state due to evaporation. Photolithography and deep reactive ion etching were used to fabricate a well-defined silicon micropillar array with diameter, height, and center-to-center spacings of 5.3, 21.7 and 27.5 μm, respectively. Water droplets placed on this microstructured surface at room temperature demonstrated superhydrophilic behavior with liquid filling the voids between pillars resulting in a vanishing contact angle. However, when the microstructured surface was superheated above a critical value, the superhydrophilicity was lost and non-wetting Cassie droplets were formed. The superheat required to deposit a Cassie droplet (>75°C) was found to be significantly higher than that required to sustain an already deposited Cassie droplet (<35°C). Interestingly, the superheat required to sustain a Cassie droplet after the initial deposition was found to decrease with the square of the droplet radius. These observations where an inherently superhydrophilic structured surface turns into superhydrophobic at nominal superheats has implications for phase change based heat transfer applications where the loss of contact between the substrate and the heat transfer fluid can be detrimental to the device performance.

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Yin, Zhiyao, Peter Kutne, Jochen Eichhorn, and Wolfgang Meier. "Experimental Investigations of Superheated and Supercritical Injections of Liquid Fuels." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16037.

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Abstract Single- and multi-component liquid fuels are injected in a jet-in-coflow configuration at elevated temperatures and pressures with both a custom plain orifice nozzle and a commercial pressure-swirl atomizer. The transitions in spray morphology from mechanical breakup to superheated/supercritical regimes are characterized qualitatively by laser shadowgraphy and evaluated based on quantitative measures of superheat. Although fuel preheating exhibits no discernible effect in the mechanical breakup regime, dramatic jet-to-plume transition as well as build up of fuel vapor in the spray chamber are observed with increasing level of superheat. The difference between two different atomizers in terms of spray behavior diminishes at high levels of superheat, suggesting the predominant role of thermal effect on spray morphology in superheated/supercritical regimes. For a mutli-component fuel such as Jet A-1, the transition into a fully flashing spray occurs at temperatures lower than expected values, which are calculated by treating Jet A-1 as a single-component fuel. Additionally, pressure drop is shown as a sensitive indicator for the departure from mechanical breakup and the onset of thermal effect on the spray. Comparisons between measured and estimated pressure drop also reveal the differences in susceptibility to thermal effects between the plain orifice and the pressure-swirl atomizers.

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Varchmin, Andreas, Manuel Gräber, Wilhelm Tegethoff, and Jürgen Köhler. "Superheat Control with a Dynamic Inverse Model." In the 10th International Modelica Conference, March 10-12, 2014, Lund, Sweden. Linköping University Electronic Press, 2014. http://dx.doi.org/10.3384/ecp14096867.

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Gunn, Stanley, and Rolv Hundal. "Design of superheat nuclear thermal rocket engine." In 30th Joint Propulsion Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1994. http://dx.doi.org/10.2514/6.1994-2895.

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Elliott, Matthew S., Bhaskar Shenoy, and Bryan P. Rasmussen. "A control architecture solution to superheat nonlinearity." In 2010 American Control Conference (ACC 2010). IEEE, 2010. http://dx.doi.org/10.1109/acc.2010.5531221.

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7

Wilkes, Colin. "Statistical Determination of Natural Gas Superheat Requirements." In 2002 International Joint Power Generation Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ijpgc2002-26036.

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The ASME Fuel Specification B133.7M [1] states that a typical margin of 25 to 30° C (45 to 54° F) of superheat is used for natural gas fuel but offers no basis for the estimate. The purpose of this paper is to propose a method for the safe determination of superheat that is less conservative, yet will meet the six sigma requirement of less than 4 defects (condensate formation) in one million opportunities. A drop in the total temperature of natural gas will be experienced as the gas expands in pressure reducing stations and across control valves. If the temperature falls below the hydrocarbon or moisture dew point, condensation will take place and liquids will collect or will be entrained with the gas. The temperature drop is inversely proportional to the pressure drop and is often termed ‘Joule-Thomson cooling’ or ‘J-T cooling’. The rate of cooling is described by the Joule-Thomson coefficient that can be determined by experiment or calculated from the gas composition. Superheating the gas prior to expansion can prevent condensation. The degree of superheat required for hydrocarbons, however, is often greater than the expected temperature loss across the valve as the hydrocarbon dew point may increase as the pressure falls. This paper describes a method for determining the quantity of superheat required for a specific gas composition and develops a general equation in terms of gas supply pressure that will satisfy the needs for the majority of natural gases. The general equation is based on the statistical analysis of superheat requirements for over 230 natural and liquefied natural gas compositions. A similar equation is also presented that describes the superheat requirements to avoid moisture condensation. The two equations can be used to specify the heating requirements upstream of pressure reducing stations or control valves.

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Lesin, S., A. Baron, H. Branover, and Jose C. Merchuk. "DIRECT CONTACT BOILING AT THE SUPERHEAT LIMIT." In International Heat Transfer Conference 10. Connecticut: Begellhouse, 1994. http://dx.doi.org/10.1615/ihtc10.580.

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Jaikumar, Arvind, and Satish G. Kandlikar. "Pool Boiling Inversion on Surfaces With Separate Liquid-Vapor Pathways and Enhanced Macroconvection Mechanisms." In ASME 2017 15th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icnmm2017-5531.

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A typical pool boiling curve relating the heat flux and wall superheat is often used to quantify the efficacy of the engineered surfaces. Surface enhancements promoting nucleation activity, wicking, roughness and microlayer partitioning have shown remarkable enhancements in CHF and HTC. The boiling curve for these surfaces show an increase in wall superheat with an increase in heat flux. However, recently developed surfaces using the concept of separate liquid-vapor pathways and enhanced macroconvection have shown a reverse trend where an increase in heat flux is accompanied by decreasing wall superheats. This counter intuitive trend in the boiling curve characteristics is called as boiling inversion in this work. The macroconvection heat transfer is identified as the contributing mechanism to the boiling inversion trend. The vapor-stream induced flow transition and the impinging liquid jet characteristics is quantitatively explained through analytical models available in literature. Furthermore, two surfaces exploiting this mechanism is also demonstrated in this work which sheds light on the interplay mechanisms.

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Abishek, S., R. Narayanaswamy, and V. Narayanan. "Effect of Heater Size on Confined Subcooled Jet Impingement Boiling." In ASME 2012 Heat Transfer Summer Conference collocated with the ASME 2012 Fluids Engineering Division Summer Meeting and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ht2012-58205.

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Jet impingement boiling heat transfer is a potential technique for the removal of very high heat fluxes concentrated at discrete locations, such as in power electronic components. In the present research, the effect of heater-nozzle size ratio (in the range 0.5 ≤ wH/wN ≤ 11) on jet impingement boiling is studied numerically. A steady-state submerged and confined subcooled jet impingement boiling of de-ionized and degassed water (at atmospheric pressure) on a polished isothermal heater surface is considered for a jet Reynolds number of Rew = 2500 and 20°C subcooling. The RPI wall boiling closure is used for the partition of heat flux on the surface into liquid phase, evaporation and quenching. Turbulence is modeled using the RNG-k-ε mixture model. The flow and heat transfer is simulated by considering the liquid and vapor phase to be an Euler-Euler interpenetrating continua; the interfacial momentum transfer is modelled using appropriate correlations for interphase momentum, heat and mass transfers. Validation of the numerical approach was performed by comparison of the present results with experimental data from literature for axisymmetric as well as slot jets. It was found that for any prescribed wall superheat, the heat flux was consistently larger for relatively smaller heaters (or smaller wH/wN). However, for any given wall superheat, the heat flux stagnated at an apparent asymptotic limit with increase in heater size, and this asymptotic limit was larger for larger wall superheats. It was also found that the quenching heat flux was the largest contributor to the total heat flux at relatively large degrees of superheat irrespective of heater-nozzle size ratio. A correlation is also developed for the heat flux as a function of the heater size and degree of superheat, for a given set of other controlling parameters.

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Reports on the topic "Superheat"

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N. Environmental Assessment for Authorizing the Puerto Rico Electric Power Authority (PREPA) to allow Public Access to the Boiling Nuclear Superheat (BONUS) Reactor Building, Rincon, Puerto Rico. Office of Scientific and Technical Information (OSTI), February 2003. http://dx.doi.org/10.2172/823492.

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Waller, Christopher J., Mariana Rojas Breu, and Aleksander Berentsen. What is the Value of Being a Superhost? Federal Reserve Bank of St. Louis, 2019. http://dx.doi.org/10.20955/wp.2019.019.

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Shaughnessy, D., K. Moody, R. Henderson, J. Kenneally, J. Landrum, R. Lougheed, J. Patin, et al. New Fragment Separation Technology for Superheavy Element Research. Office of Scientific and Technical Information (OSTI), January 2008. http://dx.doi.org/10.2172/926047.

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Terry C. Totemeier. Fatigue Testing of Metallurgically-Bonded EBR-II Superheater Tubes. Office of Scientific and Technical Information (OSTI), December 2006. http://dx.doi.org/10.2172/911861.

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Sharp, William (Sandy). Superheater Corrosion In Biomass Boilers: Today's Science and Technology. Office of Scientific and Technical Information (OSTI), December 2011. http://dx.doi.org/10.2172/1048711.

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D'Alfonso, Kenneth. Projecting Benevolent Power: Transforming America's Image from Superpower to Superhero. Fort Belvoir, VA: Defense Technical Information Center, March 2010. http://dx.doi.org/10.21236/ada519889.

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Van Weele, S. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings. Office of Scientific and Technical Information (OSTI), August 1991. http://dx.doi.org/10.2172/5767769.

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Read, D. T., and H. I. McHenry. Postweld heat treatment criteria for repair welds in 2-14Cr-1mo superheater headers :. Gaithersburg, MD: National Bureau of Standards, 1988. http://dx.doi.org/10.6028/nbs.ir.87-3075.

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Van Weele, S. Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings. Final report. Office of Scientific and Technical Information (OSTI), August 1991. http://dx.doi.org/10.2172/10124364.

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J.T. Birkholzer. TH{_}PULSE Program for Calculating Infiltration of Episodic Liquid Fingers in Superheated Rock Fractures. Office of Scientific and Technical Information (OSTI), June 2002. http://dx.doi.org/10.2172/808034.

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