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Comportamento mecânico e acústico em arenitos submetidos ao ciclo de aquecimento e resfriamentoSampaio, Igor Almeida January 2018 (has links)
Com o aumento crescente das restrições ambientais acompanhado do aumento crescente da demanda energética e matéria-prima pela população que cresce em proporções assustadores com poucos indícios de sua descida fizeram com que buscassem alternativas com viabilidade econômica e reduzisse os impactos ambientais. Para o carvão mineral, a alternativa encontrada é a Gaseificação do Carvão em Subsolo. Das vantagens encontradas com o processo, as mais interessantes são: a segurança operacional e pouca infraestrutura necessária, competitividade no preço do produto gerado (gás sintético) e pouco gerenciamento do rejeito produzido já que as cinzas são deixadas nas cavidades em subsolo. Uma das dificuldades encontradas é mostrar a mudança do comportamento mecânico e acústicos das rochas e maciço rochoso quando submetido a alta temperatura ou pós-operacional com o resfriamento das cavidades geradas durante o processo. O maciço rochoso, o sistema de fraturas e as suas propriedades mecânicas (resistência à compressão e resistência à tração) e as propriedades física (permeabilidade e anisotropia) influênciam o design operacional do processo. Com os resultados obtidos foi possível uma interdependência linear entre as velocidades das ondas P e S, essa mesma interrelação foram observadas antes e depois do ciclo de aquecimento e resfriamento com coeficiente de determinação (R²) de 0,9177 e 0,9472, respectivamente. As velocidades das ondas P e S são reduzidas com a temperatura. A redução é mais evidente na onda P com redução máxima de 39% do valor inicial. A velocidade da onda S é reduzida continuamente a partir dos 800°C, passando de 7 % para 3% da velocidade inicial. A regressão feita com a resistência à compressão dos ensaios triaxiais diverge dos resultados obtidos nos ensaios uniaxiais. Os resultados da resistência à tração e os de resistência à compressão apresentaram aumento e redução da resistência em diferentes temperaturas. A resistência à compressão não apresentou qualquer regressão com as velocidades ultrassônicas, enquanto que o módulo de Elasticidade estático apresentou uma regressão linear crescente com a velocidade da onda P com coeficiente de determinação (R²) de 0,7922. / With the increasing increase of environmental restrictions, accompanied by an increasing increase in energy and raw material demand by the population that grows to frightening proportions with little evidence of their descent, they have sought to find alternatives with economic viability and reduce environmental impacts. For coal, the alternative found is Coal Gasification in Subsoil. Of the advantages found in the process, the most interesting are: operational safety and little infrastructure required, competitiveness in the price of the product generated (synthetic gas) and little management of the waste produced since the ashes are left in the underground cavities. One of the difficulties is to show the change in the mechanical and acoustic behavior of rocks and rock mass when submitted to high temperature or postoperational with the cooling of the cavities generated during the process. The rock mass, the fracture system and its mechanical properties (compressive strength and tensile strength) and physical properties (permeability and anisotropy) influence the operational design of the process. With the results obtained, a linear interdependence between the P and S velocities was possible. This same interaction was observed before and after the heating and cooling cycle with coefficient of determination (R²) of 0,9177 and 0,9472, respectively. P and S wave velocities are reduced with temperature. The reduction is more evident in the P wave with a maximum reduction of 39% of the initial value. The S wave velocity is continuously reduced from 800 ° C, from 7% to 3% of the initial velocity. The compressive strength with the triaxial tests differs from the results obtained in the uniaxial tests. The results of the tensile strength and the compressive strength showed increase and reduction of the resistance with different temperatures. The compressive strength did not show any regression with the ultrasonic velocities, while the static elasticity modulus presented an increasing linear regression with the P-wave velocity with determination coefficient (R²) of 0,7922.
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Estudo da degradação térmica de emulsões via espectroscopia UV-Vis aplicado a fluidos de corte / Study on the thermal degradation of emulsions via UV-VIS spectroscopy applied to metalworking fluids.Victor Postal 31 October 2016 (has links)
O monitoramento de emulsões utilizadas na indústria metalmecânica compõe uma importante atividade para o controle da qualidade das peças trabalhadas, proporcionando também o aumento da vida útil de ferramentas e maquinários utilizados neste setor através da lubrificação e refrigeração da região de corte. Em grande parte dos casos, estas emulsões são preparadas pela diluição de um fluido de corte em meio aquoso, constituindo assim um conjunto de gotículas estabilizadas em um meio contínuo devido à presença de compostos emulsificantes, estando constantemente sujeitas a ciclos de aquecimento e resfriamento durante os processos de usinagem. Apesar do acompanhamento deste material ser realizado através de análises periódicas usuais, não há um método eficiente estabelecido para verificar sua qualidade em tempo real e em linha de processo. Neste contexto, torna-se possível aplicar técnicas relacionadas à espectroscopia UV-Vis para se obterem informações sobre a estabilidade destes sistemas, correlacionando intensidades de espalhamento de luz com as dimensões das gotas presentes no meio. Dessa forma, tornou-se possível o estudo da desestabilização térmica de emulsões de um fluido de corte comercial, a qual mostrou-se, através do acompanhamento do cálculo do expoente do comprimento de onda, dependente do tempo de exposição ao aquecimento e de sua temperatura média temporal, não sendo influenciada pela perda de meio contínuo por processos evaporativos ou sua posterior reposição. Também se verificou que parâmetros típicos do processo de preparo de emulsões, como a temperatura do meio dispersante e o tempo de repouso do fluido de corte sobre a superfície do mesmo, apresentam fundamental importância para a definição do tamanho médio de gota inicial destes sistemas, o que forneceu evidência da possibilidade de se relacionar a área sob espectros de extinção de luz com tamanhos médios de gota. / The monitoring of emulsions used in the metal-mechanical industry comprise an important activity to the quality control of the products manufectured, also providing an increase in the working life of the tools and machinery employed in this sector through the lubrication and refrigeration of the cutting zone. In the majority of cases, these emulsions are prepared diluting a metalworking fluid in an aqueous media, constituting a collection of particles stabilized by emulsifiers and undergoing heating and cooling cycles during metalworking processes. Currently, monitoring routines are based on regular analyses of samples taken from the process fluid, and an effective in-line method is not available to monitor emulsion quality in real time. In this context, it is possible to apply techniques related to UV-Vis spectrocopy in order to obtain information concerning the stability of those systems, correlating light scattering intensities to the droplet dimensions. In this study, it was possible to investigate the thermal destabilisation of a commercial metalworking fluid emulsion, which showed, through the evaluation of the wavelength exponent, to be dependant on the exposure time to heating and its time-averaged temperature. It was also noted that the loss of continuous phase by evaporation and its reposition do not affect the emulsion stability. Moreover, it was observed that important emulsion preparation parameters, such as continuous phase temperature and the time span between the addition of the metalworking fluid on the water surface and the stirring, have fundamental roles in defining the initial average droplet size, which made possible to correlate the area under the light extinction spectra with average droplet sizes.
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The Effect Of Sun Spaces On Temperature Patterns Within Buildings: Two Case Studies On The Metu CampusKirmizi, Hacer 01 October 2010 (has links) (PDF)
The aim of this study was to investigate the passive and active parameters affecting
energy efficiency of two office buildings with sun spaces, namely the MATPUM
Building and the Solar Building on the Middle East Technical University (METU)
Campus, Ankara and the effect of sun spaces on temperature patterns within
mentioned buildings. Both buildings were oriented in the same direction, namely
south. However, the location and the type of the sunspaces differed from each other.
The sun space in the MATPUM Building is an atrium which has southerly glazed
faç / ade. On the other hand, the sun space in the Solar Building is an enclosed
conservatory which has southerly glazed faç / ades and roof.
The effect of sun spaces on temperature patterns within case study buildings was
determined by collecting internal temperature and humidity data from different locations within the buildings and external temperature and humidity data on certain
days of the week from May to August and October and November. Data loggers
were used to collect these data. The collected data was then compared for the two
buildings and also for the different months. In conclusion, more heat gain resulting in
temperature increase inside the buildings was obtained in conservatories when
compared to the atria which have glazed faç / ade instead of glazed roof. This was also
proved by the analysis of variance method which was used for the comparison of
temperature data of two buildings
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Simulační model leteckého pístového spalovacího motoru / Simulation model of an aircraft internal combustion piston engineOlšovský, Petr January 2018 (has links)
This master’s thesis deals with creating a real-time simulation model of an aircraft piston engine with emphasis on heating and cooling of the engine cylinders. First part of this thesis focuses on characteristics of aircraft engines and differences with regular automotive engines. The next chapter describes the dependence of engine parameters on atmospheric conditions. The description of the real time model itself follows next. The results of the simulation model are presented and analysed at the end of this thesis.
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Electricity Projection with Peak Load Shifting Strategy in Wuxi Sino-Swedish Eco-CitySu, Chang January 2013 (has links)
Wuxi Sino-Swedish Eco-City, a pilot city region with an area of 2.4 km2, is a demonstration project for innovation in energy technology and integrated smart city solutions in China. After the 1st phase of the project, general outlines of the city’s energy system were drawn and applicable technologies are provided. However, no work has been performed on building electricity load projection and load analysis. This thesis will therefore firstly focus on establishing the building electricity load projection model, using simulation software STELLA. Then the model is scaled up for the whole city region. The simulation results show that there is foreseen to be electricity peak in summer and winter, due to the cooling and heating demand. Based on simulation results, an electricity DSM (demand side management) strategy should be implemented in order to balance the load. Peak load shifting strategy is thus chosen to be investigated. Two technology options (ice-storage system and thermal storage system), which could be implemented to balance the electricity peak, is analyzed by scenarios. Also, commercial feasibility of implementing such technologies is discussed. / Wuxi Taihu Sino-Swedish Eco-City
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Fjärrvärmedriven Absorptionskyla : En ekonomisk undersökning av olika spetslösningarStrömqvist, Bodil January 2021 (has links)
This independent degree project has been implemented on behalf of FVB Sverige AB in collaboration Sundsvall Energi AB with the initial purpose of mapping manufacturers of hot water driven absorption chillers. After that, several technical solutions are examined to manage the peak load of a theoretical object which cannot produce the cooling power required with only an absorptions chiller, due to limitations in the district heating supply. The market study has shown that the supply of absorption chillers with drive temperatures of 70–90˚C is limited to a few manufacturers. World Energy offers a unit with drive temperatures of 70 ˚C and efficiency (COP) of 0,4. Due to limitations of district heating flow, a unit with drive temperature of 85 ˚C and efficiency of 0,77 is chosen. The technical solutions are dimensioned for a building with a peak power of 264 kilowatt, where the required peak load ranges from 31 to 39 kilowatt. The technical solutions examined are a solar collector system, tap water heat exchanger, and a conventional compressor driven chiller. The solar collectors are dependent on location but use no refrigerants that are affected by the F-gas regulation. The tap water solution consumes large flows of tap water, but the installation is simple. The conventional chiller is not location dependent but uses ozone degrading refrigerants and has a high cost of operation. From an economic perspective the technical solutions are equally profitable with a present net value of approximately 500 000 SEK and pay-back of 13 years. The examination has also shown that the present value is one million crowns in sales of heat and building after a ten-year period. In conclusion the conventional chiller has the biggest prerequisites to be used as a standardised solution for buildings with a bigger cooling load. Based on the technical and economical conditions.
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Laminar heat transfer to Newtonian and Non-Newtonian fluids in tubes. Temperature and velocity profiles were determined experimentally for heating and cooling of Newtonian and non-Newtonian fluids in tubes and the results compared with theoretical predictions incorporating a temperature-dependent viscosity.Pavlovska-Popovska, Frederika January 1975 (has links)
This thesis is concerned with a theoretical and experimental
study of the hydrodynamics and heat transfer characteristics
of viscous fluids flowing in tubes under laminar conditions.
Particular attention has been given to the effects of the rheological
properties and their variation with temperature. A review of
problems of this type showed that in spite of the many potential
applications of the results in a wide range of industries
the subject had not been well developed and further work is justified in order to fill some of the gaps in our knowledge.
The early part of the thesis considers the justification of the
work in this way and sets down the scope and objectives. A computer progracune was then developed to allow the
governing equations of the problem to be solved numerically to
give the velocity and temperature profiles and pressure drop for
both heating and cooling conditions. The results were also
presented in the form of Nusselt numbers as a function of the
Graetz numberp since this form is useful for engineering design
purposes. The validity of the predictions were then checked by a
programme of experimental work. Temperature and velocity profiles
have been measured in order to provide a more severe test of the
theory than could be imposed by the measurement of overall heat
transfer rates. A combined thermocouple probe/Pitot tube was
developed to allow simultaneous measurements of velocity and
temperature to be made. A Newtonian oil and two non-Newtonian
Carbopol solutions were studied. This is the first time that
velocity and temperature profiles have been measured for non-Newtonian
fluids in this type of situation. The results of the work heve shown that
(a) the velocity and temperature profiles and pressure
drops are greatly affected by the temperature dependence
of the rheological properties and since real viscous
fluids are normally very temperature-sensitive it is
important that this effect is properly taken into
account.
(b) the engineering design correlations commonly used for
the prediction of heat transfer coefficients can be
seriously in error, especially for cooling conditions
and when non-Nevitonian fluids are being considered.
(c) a mathematical model can be developed which accurately
describes all the phenomena and gives predictions which
are very close to those observed experimentally. An important objective was to develop more accurate engineering
design correlations for non-isothermal pressure drop and heat
transfer rates. / University of Bradford
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Gyvenamojo namo šildymo ir vėdinimo sistemos kompiuterinio valdymo modelio sudarymas ir tyrimas naudojant Petri tinklą / Modeling and analysis of house heating and cooling computer control system using Petri netsKriščiūnas, Darius 22 May 2005 (has links)
Presently information systems are increasingly penetrating to our daily life. Recently it is relevant to integrate the newest technologies. In that way traditional system becomes “smart” who are more economical, optimal, and self-sufficient. The biggest problem is to make a model of “smart” system. There were analyzed modeling methods, heating and cooling control systems in this job. Mathematical model for heating and cooling controller using timed Petri nets was presented. According to analyzed problems it was made verification with Matlab during experimental phase. There was made comparison evaluation of mathematical model made with timed Petri nets and fuzzy logic.
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Développement de modèles de bâtiment pour la prévision de charge de climatisation et l’élaboration de stratégies d’optimisation énergétique et d’effacement / Development of building models for load curve forecast and design of energy optimization and load shedding strategiesBerthou, Thomas 16 December 2013 (has links)
Pour atteindre les objectifs de réduction de consommation et augmenter la flexibilité de la demande des bâtiments, il est nécessaire de disposer de modèles de prévision de charge de climatisation facilement diffusables sur site et performants qui permettent la mise en place de stratégies d’optimisation énergétique et d’effacement. Cette thèse compare plusieurs architectures de modèles inverses (« boite noire », « boite grise »). Un modèle semi-physique d’ordre 2 (R6C2) a été retenu pour prévoir la puissance de climatisation et la température intérieure moyenne en chauffage et en refroidissement. Il permet aussi d’interpréter des situations inédites (effacement), absentes de la phase d’apprentissage. Trois stratégies d’optimisation énergétique et d’effacement adaptées aux contraintes d’exploitation sont étudiées. La première permet d’optimiser la relance en chauffage afin de réduire la consommation et d’atteindre effectivement la température de confort le matin. La seconde stratégie optimise les températures de consigne sur une journée dans un contexte de prix variable de l’énergie, ceci afin de réduire la facture énergétique. Enfin, la troisième stratégie permet au bâtiment de s’effacer en limitant la charge tout en respectant des critères de confort spécifiés. Le modèle R6C2 et les stratégies ont été confrontés à un bâtiment réel (une école élémentaire). L’étude montre qu’il est possible de prévoir la puissance électrique et la température moyenne d’un bâtiment complexe avec un modèle mono-zone ; elle permet d’évaluer les stratégies développées et d’identifier les limites du modèle. / To reach the objectives of reducing the energy consumption and increasing the flexibility of buildings energy demand, it is necessary to have load forecast models easy to adapt on site and efficient for the implementation of energy optimization and load shedding strategies. This thesis compares several inverse model architectures ("black box", "grey box"). A 2nd order semi-physical model (R6C2) has been selected to forecast load curves and the average indoor temperature for heating and cooling. It is also able to simulate unknown situations (load shedding), absent from the learning phase. Three energy optimization and load shedding strategies adapted to operational constraints are studied. The first one optimizes the night set-back to reduce consumption and to reach the comfort temperature in the morning. The second strategy optimizes the set-point temperatures during a day in the context of variable energy prices, thus reducing the energy bill. The third strategy allows load curtailment in buildings by limiting load while meeting specified comfort criteria. The R6C2 model and strategies have been faced with a real building (elementary school). The study shows that it is possible to forecast the electrical power and the average temperature of a complex building with a single-zone model; the developed strategies are assessed and the limitations of the model are identified.
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Metodología práctica para evaluar la viabilidad de redes de frio y calor urbanas integrando energía solar y biomasa en la España cálidaGalvany Castillo, Francisco Jose 01 March 2016 (has links)
[EN] For more than a decade, the urban heat networks (District Heating, DH) combined with the use of renewable energies have been consolidated as a leading tool for energy efficiency and reducing emissions of greenhouse gases.
Among the various possibilities of generation in the North and Central Europe, with little or no annual demand for comfort cooling, since the 80s a large number of facilities, that use solar energy with large seasonal accumulators capable to store surplus heat captured in the period of increased solar availability and minimum demand (summer) and hold until the time of heating demand (autumn), have been built. In this type of installation, the cost of seasonal storage represents a significant percentage of investment for DH.
In warmer countries of southern Europe, as in the case of Spain, where in most of the territory the energy demand for cooling is more important or the same order as the heating demand, and taking into account the high costs incurred by the seasonal deposits, a more efficient solution would be using solar energy in summer to cover a percentage of the cooling by thermal chillers (absorption / adsorption). These systems today have little implementation compared to the previous ones, and design criteria do not allow a systematic approach regarding the possible configurations and sizing of the various teams. This Is the technical solution proposed in this thesis.
In the present thesis, after a timely review of the state of the Solar District Heating art, SDHC, a technical solution is proposed, intended to be easily replicable, of generation for a solar installation of hot and cold coupled to an urban network to four tubes, District Heating & Cooling, DHC. In addition, practical aspects of the business model for the operation of the network are reviewed. Two TRNSYS dynamic simulation models are developed: One for the DHC and one prior to the study of demand. A practical methodology is also provided on a first initial study to evaluate the technical and economic viability of future projects based on the same technical solution.
Finally, the discussion in the previous chapters is expressed in the development of a case study. The DHC studied supplied cold and heat to 2,228 new housing in a suburb of Valencia capital.
In view of energy, economic and environmental results of the case study, it is concluded that the proposal for a DHC in Valencia, as the representative city of the warm Spain, technical solution is a viable option generation and energy supply in the residential sector (and associated tertiary). / [ES] Desde hace más de una década, las redes de calor urbanas (District Heating, DH) combinadas con el uso de energías renovables se han consolidado como una herramienta de primer orden para la eficiencia energética y la reducción de emisiones de gases de efecto invernadero.
Entre las distintas posibilidades de generación, en los países del Norte y Centro de Europa, con escasa o nula demanda anual de refrigeración en las viviendas, desde los años 80 se han construido un gran número de instalaciones que utilizan energía solar con grandes acumuladores estacionales capaces de almacenar el calor excedente captado en la época de mayor disponibilidad solar y mínima demanda (verano), y mantenerlo hasta la época de demanda de calefacción de otoño. En este tipo de instalaciones, el coste del acumulador estacional representa un porcentaje muy significativo dela inversión para el DH.
En los países más cálidos de Sur de Europa, como el caso de España, donde en gran parte del territorio la demanda energética para refrigeración es más importante o del mismo orden que la demanda de calefacción, y teniendo en cuenta el alto coste que suponen los depósitos estacionales, una solución más eficiente podría ser la que utiliza la energía solar en época estival para cubrir un porcentaje de la demanda de frío mediante enfriadoras térmicas (absorción/adsorción). Estos sistemas tienen, a día de hoy, poca implantación en comparación con los anteriores, y no existen criterios de diseño consolidados que permitan una sistemática en cuanto a las posibles configuraciones y dimensionamiento de los distintos equipos. Esta última opción es la solución técnica que se propone en esta tesis.
En la presente tesis, tras una oportuna revisión del estado del arte de los Solar District Heating, SDHC, se propone una solución técnica de generación, que se pretende fácilmente replicable, para una instalación solar de frío y calor acoplada a una red urbana a cuatro tubos, District Heating & Cooling ,DHC. Además, se revisan aspectos prácticos del modelo de negocio para la explotación de la red. Se desarrollan dos modelos de simulación dinámica TRNSYS: uno para el DHC y uno previo para el estudio de la demanda. También se proporciona una metodología práctica que permita, en un primer estudio inicial, evaluar la viabilidad técnico-económica de los futuros proyectos basados en la misma solución técnica.
Por último, lo expuesto en los capítulos previos se concreta en el desarrollo de un caso práctico. El DHC estudiado suministra frío y calor a 2.228 viviendas de nueva construcción en barrio periférico de Valencia capital.
A la vista de los resultados energéticos, económicos y medioambientales obtenidos en el estudio del caso, cabe concluir que la solución técnica propuesta para un DHC en Valencia, como ciudad representativa de la España cálida, constituye una opción viable de generación y suministro energético en el sector residencial (y terciario asociado). / [CAT] Des de fa més d'una dècada, les xarxes de calor urbana (District Heating, DH) combinades amb l'ús d'energies renovables s'han consolidat com una ferramenta de primer orde per a l'eficiència energètica i la reducció d'emissions de gasos d'efecte hivernacle.
Entre les distintes possibilitats de generació, en els països del Nord i Centre d'Europa, amb escassa o nul.la demanda anual de refrigeració en les vivendes, des dels anys 80 s'han construït un gran nombre d'instal·lacions que utilitzen energia solar amb grans acumuladors estacionals capaços d'emmagatzemar la calor excedent captat en l'època de major disponibilitat solar i mínima demanda (estiu) i mantindre-ho fins a l'època de demanda de calefacció. En este tipus d'instal·lacions, el cost de l'acumulador estacional representa un percentatge molt significatiu de la inversió per al DH.
En els països més càlids de Sud d'Europa, com el cas d'Espanya, on en gran part del territori la demanda energètica per a refrigeració és més important o del mateix orde que la demanda de calefacció, i tenint en compte l'alt cost que suposen els depòsits estacionals, una solució més eficient podria ser la que utilitza l'energia solar en època estival per a cobrir un percentatge de la demanda de fred per mitjà de refrigeradors tèrmiques (absorció/adsorció). Estos sistemes tenen a hores d'ara poca implantació en comparació amb els anteriors, i els seus criteris de disseny tampoc permeten un criteri sistemàtic quant a les posibles configuracions i dimensionament dels distints equips. És la solució tècnica que es proposa en esta tesi.
En la present tesi, després d'una oportuna revisió de l'estat de l'art dels Solar District Heating, SDHC, es proposa una solución tècnica, que es pretén fàcilment replicable, de generació per a una instal·lació solar de fred i calor acoblada a una xarxa urbana a quatre tubs, District Heating & Cooling, DHC. A més, es revisen aspectes pràctics del model de negoci per a l'explotació de la xarxa. Es desenrotlla dos models de simulació dinàmica TRNSYS: un per al DHC i un previ per a l'estudi de la demanda. També es proporciona una metodología pràctica que permeta, en un primer estudi inicial, avaluar la viabilitat tècnic-econòmica dels futurs projectes basats en la mateixa solució tècnica.
Finalment, allò que s'ha exposat en els capítols previs es concreta en el desenrotllament d'un cas pràctic. El DHC estudiat subministra fred i calor a 2.228 vivendes de nova construcció en barri perifèric de València capital.
A la vista dels resultats energètics, econòmics i mediambientals obtinguts en l'estudi del cas, cal concloure que la solució técnica proposta per a un DHC a València, com a ciutat representativa de l'Espanya càlida, constituïx una opció viable de generació i subministrament energètic en el sector residencial (i terciari associat). / Galvany Castillo, FJ. (2016). Metodología práctica para evaluar la viabilidad de redes de frio y calor urbanas integrando energía solar y biomasa en la España cálida [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61306 / TESIS
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