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Este trabalho foi realizado no verão de 2002 e teve como objetivo avaliar a influência de alguns recursos de climatização na produção de leite, na termorregulação dos animais e nos investimentos nas instalações. Foram utilizadas 10 primíparas e 17 vacas em lactação, distribuídas em instalação controle (ICO), instalação com nebulizador associado a ventiladores (ICL) e instalação com tela de sombreamento. A produção de leite e o consumo individual foram medidos diariamente para cada animal. A temperatura retal foi medida três vezes ao dia, em três animais de cada instalação; a temperatura de superfície da pele, três vezes ao dia em todos os animais; e a freqüência respiratória, duas vezes ao dia em todos os animais. Os dados climáticos de cada instalação foram registrados e posteriormente calculados os índices de temperatura e umidade (ITU), de globo negro e umidade (ITGU) e a entalpia. Foram selecionados e analisados 26 dias com entalpia elevada. O índice de globo negro e umidade foi menor no tratamento climatizado, porém a entalpia menor foi observada no tratamento com tela. O índice de temperatura e umidade não diferenciou o ambiente climático das instalações. Índice de temperatura e umidade entre 75 e 76, apesar de considerado estressante por diversas fontes da literatura, não foi associado à condição de estresse pelos animais. As vacas da instalação climatizada apresentaram freqüência respiratória e temperatura de pele significativamente menor em relação às vacas das demais instalações. As primíparas apresentaram freqüências respiratórias e temperaturas retais mais altas do que as vacas, em todos os horários. A maior produção de leite das vacas do tratamento tela foi associada à menor entalpia neste tratamento, em comparação aos demais. Os resultados econômicos demonstraram que foi viável a utilização de tela de sombreamento como recurso para minimizar o calor. / This work was carried out during the summer of 2002. The objective was to evaluate the influence of some cooling systems on the milk yield, animal thermoregulation and housing investments. Ten heifers and seventeen milking cows were distributed in the control housing (ICO), mist & fan housing (ICL) and screen shade (IT). The milk yield and the individual intake were daily measured for each animal. The rectal temperature was measured three times a day with three animals from each treatment. The skin surface temperature was collected three times a day for all the animals and the respiratory frequency two times a day for all the animals. The climatic data of each housing were registered to calculate the temperature humidity index (ITU), the black globe humidity index (ITGU) and enthalpy. Twenty six days of high enthalpy were selected and analyzed. The black globe humidity index was lower for the mist & fan treatment while the lowest enthalpy was observed for the screen shade treatment. The temperature humidity index was not able to differentiate the climatic environment of the houses. The study showed that temperature humidity index between 75 and 76 was not associated with stress conditions for the animals, although many researches propose this situation as stressing. The milking cows in the mist & fan treatment showed respiratory frequency and skin surface temperature significantly lower than the cows in the other treatments. The heifers presented respiratory frequency and rectal temperature higher than the cows in all the registration times. The higher milk yield of the cows in the screen shade treatment was associated with the lower enthalpy on this treatment in comparison with the others. Economic results demonstrated that screen shade was a feasible option to decrease the heat stress of the animals.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Engineering, 1978 / Includes bibliographical references. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Nuclear Engineering

Internal combustion engines are the most commonly used engines in the automotive world. However, these engines lack an overheating prevention system against cooling system failures when they exceed their normal operating temperature. Less experienced drivers (users) usually do not notice overheating until the engine stops, generating economic expenses in engine repairs. As such, this paper describes the design and construction of an electromechanical device to prevent engine overheating. This device is installed in a vehicle and operates independently from the electronic control unit (ECU); it records the coolant temperature and controls air admission to the engine of the vehicle in which it is installed. In addition, a new Arduino-based card will receive signals from a temperature sensor as input and process them according to its programming. Then, it will send signal outputs to the actuators: A servomotor, monitor, LED display, and buzzer. To control the intake flow, a butterfly valve is used with the servomotor. This valve partially or totally restricts the engine airflow, based on the temperature programmed for the Arduino, thus protecting the engine from overheating.

No description available.

As the importance of water use in the power generation sector increases across the nation, the ability to obtain and analyze real power plant data is pivotal in understanding the water energy nexus. The Navajo Generating Station in Arizona and the Browns Ferry Nuclear Plant in Alabama are examples of where water shortages have threatened the operation of power generators. The availability of freshwater in the United States is beginning to dictate how and where new power plants are constructed. The purpose of this study is to provide and analyze cooling system parameters using 2008 data provided by the Energy Information Administration. Additionally, the cost of water saved among different categories of power plants is calculated. In general, the conditions which cause cooling systems to withdraw less water are not necessarily the more expensive conditions, and vice versa. While not all the variability in the cost of cooling systems is being accounted for, the results from this study prove that nameplate capacity, capacity factor, age of power plant, and region affect the costs of installed cooling systems. This study also indicates that it would be most cost effective for once-through cooling systems to be replaced with recirculating- pond instead of recirculating- tower systems. The implications of this study are that as power plant owner's struggle in balancing cost with water dependence, several parameters must first be considered in the decision-making process. / Master of Science

Creating a sense of place through a comfortable indoor condition is a goal of the architectural design process. Thermal comfort is an important component of this condition. To achieve thermally comfortable environments mechanical systems such as Radiant Cooling (RC) could be used. RC systems have potential benefit of lower energy consumption when compared to other common cooling, ventilating and air-conditioning systems. Decisions related to the use of mechanical systems such as these should be considered in the early stages of design to maximize the building performance through systems integration and minimize redesign as part of the design process. RC systems have several special demands and related variables. Architects, HVAC system engineers, and decision-makers have to understand these issues and variables and their impact on the other building performance mandates. Through this understanding, these professionals can better evaluate tradeoffs to reach the desired solution of the design problem. Unfortunately, in the United States few architects and engineers have experience with RC systems which in turn limits the application of these systems. Through systematic literature review, a series of case studies, and interviews with experienced professionals, this research captures and structures knowledge related to how decisions are made concerning RC systems. Through this knowledge capturing procedure, the relevant design performance mandates, barriers and constraints, and potential advantages and benefits of radiant cooling systems are determined and mapped to a decision-support framework. This framework is graphically presented which may later be translated to a decision-support software package which could then be developed as a radiant cooling system design assistance tool for architects and HVAC engineers. / Ph. D.

[EN] In a context of global warming concern and global energy policies, in which heating and cooling systems in buildings account for a significant amount of the global energy consumption, ground source heat pump (GSHP) systems are widely considered as being among the most efficient and comfortable heating and cooling renewable technologies currently available. Nevertheless, both an optimal design of components and an optimal operation of the system as a whole become crucial so that these systems can have a significant contribution to the attenuation of the global energy problem. The overall objective of this PhD dissertation is to perform the control and energy optimization of an experimental GSHP system installed at the Universitat Politècnica de València, making the control system adaptive to the thermal demand of the building and to the climate conditions. For that purpose, different control strategies are proposed, described, developed, implemented and tested in the system. The optimization of any system requires a comprehensive study of its behaviour, by means of a thorough analysis of all the variables and parameters implied on its performance. Therefore, the first step is to analyse the short-term performance of the system, but also the long-term performance based on the experimental data collected at the installation. Second and prior to developing any optimization strategies, it is important to analyse the optimal configuration of the system according to the objectives targeted. This objective includes the study of the best location for the temperature control sensor and the buffer tank, as well as an adequate size for this buffer tank. Finally, once the behaviour of the system has been fully understood, the components of the system are the most efficient according to the possibilities of the research work and they have been connected adequately, the final objective is to develop control and optimization strategies which optimize the operation of the experimental GSHP system. These strategies target the control of the heat pump compressor, but also and more importantly, the energy optimization of the complete system. The focus is not in optimizing the performance of each individual component, but in optimizing the energy performance of the system working as a whole. In this direction, a first approach which combined a temperature compensation strategy and the variation of the frequency of the water circulation pumps, and hence the flow rate, as a function of the thermal load of the building, was first attempted. The application of this first approach resulted in significant energy savings, but also in a lack of user comfort in some of the offices under extreme weather conditions during summer. Consequently, the control and optimization methodology has been upgraded in a global algorithm (which is the final result of this PhD thesis) which couples both strategies in order to ensure the user comfort while keeping significant energy savings. In brief, this PhD work provides a comprehensive experimental study for the energy optimization of a GSHP system for both cooling and heating operation. Experimental results for a one-year operation period demonstrate important energy savings when compared to the standard control operation, up to 35% in the summer season and 53% in the winter season, while keeping the user comfort. / [ES] En un contexto de creciente preocupación por el calentamiento global y de políticas energéticas internacionales, en el cual los sistemas de climatización en edificios representan una parte importante del consumo energético global, los sistemas de bomba de calor geotérmica están ampliamente considerados como una de las tecnologias de climatización de espacios más eficientes disponibles en la actualidad. Sin embargo, tanto un buen diseño de los componentes como una óptima operación del sistema son de vital importancia para que estos sistemas puedan contribuir de manera significativa a atenuar el problema energético global. El objetivo general de esta tesis doctoral es el control y la optimización energética de una instalación experimental de bomba de calor geotérmica construida en la Universitat Politècnica de València, haciendo que el sistema de control se adapte a la demanda térmica del edificio y a las condiciones climatológicas. Para ello, se proponen diferentes estrategias de control, las cuáles son descritas, desarrolladas, implementadas y evaluadas a lo largo de este trabajo de investigación. La optimización de cualquier sistema requiere un amplio estudio de su comportamiento, analizando concienzudamente todas las variables y parámetros implicados en su funcionamiento. Por tanto, el primer paso llevado a cabo es el análisis de los días típicos de funcionamiento de la instalación, pero también su comportamiento a más largo plazo, a partir de los datos experimentales recogidos. En segundo lugar, y como paso previo al desarrollo de las estrategias de optimización, es importante analizar la configuración óptima del sistema de acuerdo con los objetivos perseguidos. Este objetivo incluye el estudio de la posición del sensor de temperatura empleado para el control y del depósito de inercia, así como el dimensionamiento adecuado de este depósito. Finalmente, una vez se ha analizado en profundidad el funcionamiento del sistema, los componentes del mismo son lo más eficientes posible, y éstos han sido conectados de manera adecuada, el objetivo final es el desarrollo de estrategias de control y optimización energética que optimicen la operación de la instalación experimental de bomba de calor geotérmica. Estas estrategias se dirigen principalmente a la optimización del sistema completo. El objetivo no es optimizar el funcionamiento de cada componente de manera individual, sino optimizar el comportamiento energético del sistema trabajando como un todo. En este sentido, se desarrolló una primera metodología que combinaba la compensación de la temperatura de consigna de la bomba de calor en función de la temperatura ambiente exterior, y la variación de la frecuencia de las bombas de circulación (y por tanto el caudal de agua) en función de la carga térmica del edificio. La aplicación de esta primera estrategia resultó en una importante mejora del rendimiento energético, pero también en la pérdida de confort en algunas de las oficinas climatizadas cuando las condiciones climatológicas eran extremas durante el verano. En consecuencia, la metodología de control y optimización desarrollada fue mejorada dando como resultado un algoritmo global de optimización energética (que es el resultado final de esta tesis), el cual acopla ambas estrategias anteriores de manera que se cumpla el confort del usuario y se mantenga un ahorro de energía significativo. En resumen, esta tesis doctoral proporciona un estudio experimental exhaustivo de la optimización energética de un sistema de bomba de calor geotérmica para la climatización de un edificio de oficinas. Los resultados experimentales para un año completo de funcionamiento del sistema muestran un ahorro de energía significativo en comparación con el modo de control de referencia, hasta un 35% en modo refrigeración y un 53% en modo calefacción, a la vez que se mantiene el confort de los usuarios. / [CA] En un context de creixent preocupació per l'escalfament global i de polítiques energètiques internacionals, en el qual els sistemes de climatització en edificis representen una part important del consum energètic global, els sistemes de bomba de calor geotèrmica estan amplament considerats com una de les tecnologies de climatització més eficients disponibles en la actualitat pel que fa a la climatització d'espais. No obstant això, tant un bon disseny dels components com una operació òptima del sistema són de vital importància per tal que aquests sistemes puguen contribuir de manera significativa a atenuar el problema energètic global. L'objectiu general d'aquesta tesi doctoral és el control i l'optimització energètica d'una instal·lació experimental de bomba de calor geotèrmica construïda a la Universitat Politècnica de València, fent que el sistema de control s'adapte a la demanda tèrmica de l'edifici i a les condicions climatològiques. Amb aquest objectiu, es proposen diferents estratègies de control, les quals són descrites, desenvolupades, implementades i avaluades al llarg d'aquest treball d'investigació. L'optimització de qualsevol sistema requereix un ampli estudi del seu comportament, analitzant conscienciosament totes les variables i paràmetres implicats en el seu funcionament. Per tant, el primer pas duit a terme és l'anàlisi dels dies típics de funcionament de la instal·lació, però també el seu comportament a més llarg termini, a partir de les dades experimentals recollides. En segon lloc, i com pas previ al desenvolupament de les estratègies d'optimització, és important analitzar la configuració òptima del sistema d'acord als objectius perseguits. Aquest objectiu inclou l'estudi de la posició del sensor de temperatura emprat pel control i del dipòsit d'inèrcia, així com el correcte dimensionament d'aquest dipòsit. Finalment, una vegada s'ha analitzat en profunditat el funcionament del sistema, els components d'aquest són el més eficients possible, i han sigut connectats de manera adequada, l'objectiu final és el desenvolupament d'estratègies de control i optimització energètica les quals optimitzen l'operació de la instal·lació experimental de bomba de calor geotèrmica. Aquestes estratègies es dirigeixen principalment a l'optimització del sistema complet. L'objectiu no és optimitzar el funcionament de cada component de manera aïllada, sinó més bé optimitzar el comportament energètic del sistema treballant com un tot. En aquest sentit, es va desenvolupar una primera metodologia que combinava la compensació de la temperatura de consigna de la bomba de calor en funció de la temperatura ambient exterior, i la variació de la freqüència de les bombes de circulació (i per tant del cabdal d'aigua) en funció de la càrrega tèrmica de l'edifici. L'aplicació d'aquest primer apropament va resultar en una important millora del rendiment energètic, però també en la pèrdua de confort en algunes de les oficines climatitzades quan les condicions climatològiques eren extremes durant l'estiu. En conseqüència, la metodologia de control i optimització desenvolupada va ser millorada resultant en un algoritme global d'optimització energètica (resultat principal d'aquesta tesi), el qual acobla ambdues estratègies anteriors de manera que es complisca el confort de l'usuari i es mantinga un important estalvi d'energia. En resum, aquesta tesi doctoral proporciona un estudi experimental exhaustiu de l'optimit\-zació energètica d'un sistema de bomba de calor geotèrmica per la climatització d'un edifici d'oficines. Els resultats experimentals per un any complet de funcionament del sistema mostren un estalvi d'energia significatiu en comparació amb el mode de control de referencia, fins un 35% en mode refrigeració i un 53% en mode calefacció, a la vegada que es manté el confort dels usuaris. / Cervera Vázquez, J. (2016). Control and energy optimization of ground source heat pump systems for heating and cooling in buildings [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/66748

Thesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008. / This study evaluates the performance characteristics of a power plant incorporating a steam turbine and a direct air-cooled dry/wet condenser operating at different ambient temperatures. The proposed cooling system uses existing A-frame air-cooled condenser (ACC) technology and through the introduction of a hybrid (dry/wet) dephiegmator achieves measurable enhancement in cooling performance when temperatures are high. In order to determine the thermal-flow performance characteristics of the wet section of the dephlegmator, tests are conducted on an evaporative cooler. From the experimental results, correlations for the water film heat transfer coefficient, air-water mass transfer coefficient and the air-side pressure drop over a deluged tube bundle are developed. During periods of high ambient temperatures the hybrid (dry/wet) condenser operating in a wet mode can achieve the same increased turbine performance as an oversized air-cooled condenser or an air-cooled condenser rith adiabatic cooling (spray cooling) of the inlet air at a considerably lower cost. For the same turbine power output the water consumed by an air-cooled condenser incorporating a hybrid (dry/wet) dephlegmator is at least 20% less than an air- cooled condenser with adiabatic cooling of the inlet air. / Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: A passive night-sky radiation cooling system consists of a radiation panel and a cold water storage tank. The stored cold water may be used to cool a room during the day time, particularly in summer. In this thesis a theoretical and mathematically sound simulation model is developed. An experimental set-up was constructed and subsequently used to show that the theoretical model effectively simulates the transient heating or cooling response of the system. It is shown that under South African conditions the typical heat emitting rate during the night is 55 W/m2. After the heat has been removed from the water, it is stored in a cold water tank from where it is circulated through a natural convector during the day time to absorb heat from the room. The experiment extracted a minimum of 102 W/m3 of heat from a 1.87 m3 galvanized steel room while a brick room with a volume of 120 m3 requires 22.7 W/m3. Additional to cooling, the system during the day, absorbed an average of 362 W of energy and heated 68 l of water from 24 °C to 62 °C within an 8-hour period. The system achieved similar results during winter conditions and the experiment confirms that the system is capable of operating without a control system. Therefore it is recommended that renewable energy-conscious designers pay more attention to the use of night-sky radiation cooling in future. / AFRIKKANSE OPSOMMING: en ’n koue water tenk. Die sisteem kan gebruik word om ’n vertrek gedurende die dag te verkoel, veral in die somer, deur gebruik te maak van die gestoorde verkoelde water. In hierdie tesis word ’n teoretiese en sinvolle wiskundige simulasie model ontwikkel. ’n Eksperimentele stelsel is gebou en vervolgens gebruik om te bewys dat die teoretiese model die veranderende verkoeling en verwarming van die stelsel effektief simuleer. Die tesis dui aan dat onder Suid Afrikaanse toestande daar ’n hitte vrystellings tempo van 55 W/m2 is gedurende die nag. Nadat die water verkoel is, word dit gestoor in die koue water tenk vanwaar dit deur ’n natuurlike konvektor sirkuleer en gedurende die dag warmte vanuit die vertrek onttrek. Die eksperiment het ’n minimum van 102 W/m3 warmte vanuit die galvaniseerde 1.87 m3 vertrek geabsorbeer, terwyl ’n baksteen vertrek van 120 m3, 22.7 W/m3 verkoeling benodig. Bykomstig tot die verkoelingstelsel verhit die sisteem 68 l water vanaf 24 °C to 62 °C gedurende ’n 8-uur periode in die dag, dus word 362Wenergie geabsorbeer. Die sisteem is ook getoets tydens winter toestande, die resultate was dieselfde as wat in die somer verkry is. Verder is daar ook bewys dat die sisteem sonder enige beheerstelsel kan funksioneer. Verder word daar aanbeveel dat hernubare energie bewuste ontwerpers in die toekoms meer aandag aan ruimte straling verkoeling skenk.