Preliminary design package for residential heating/cooling system: Rankine air conditioner redesign

A summary of the preliminary redesign and development of a marketable single family heating and cooling system is presented. The interim design and schedule status of the residential (3-ton) redesign, problem areas and solutions, and the definition of plans for future design and development activities were discussed. The proposed system for a single-family residential heating and cooling system is a single-loop, solar-assisted, hydronic-to-warm-air heating subsystem with solar-assisted domestic water heating and a Rankine-driven expansion air-conditioning subsystem

Operational simulation and an economical modelling study on utilizing waste heat energy in a desalination plant and an absorption chiller

PhD ThesisIt is well established that a large proportion of the global emission of greenhouse gases are produced by electricity power stations and that a power plant typically emits about two thirds of its input energy as waste heat into the atmosphere. As such there is a lot of potential for additional applications that utilize this waste heat energy. Utilizing this waste heat energy in a desalination plant to produce low-cost potable water is the key to overcoming three problems at once, namely the water shortage in and and semi-arid areas, the continuing increase in oil prices by being more efficient and global warming. In all waste heat recovery or alternative energy systems based on natural phenomena (solar or wind) a major difficulty is decoupling supply from demand as thermal storage is neither efficient nor practical in many cases. A significant difficulty of gas turbine based power generation systems is the derating caused by high ambient temperatures; typically a 1% change in ambient temperature produces a similar reduction in efficiency. Therefore, by also utilizing this waste heat energy in an absorption chiller to pre-cool the gas turbine's compressor inlet-air, the effect of ambient temperature fluctuations on the gas turbine's performance would be eliminated. The combined cycle described in this study was designed in an attempt to address these issues. A gas turbine based combined heat and power plant was combined further with an absorption refrigeration unit and an MED desalination plant. The absorption unit stabilizes the operation of the gas turbine, reducing the sensitivity to changes in ambient temperature and the desalination plant acts as an energy utilization device that produces a usable product (40,000m3/day of potable water) that is easily stored and distributed as required. The simulation was performed using IPSEpro on the basis of real data obtained from an existing power plant and commercially available plants. The performance of the sub-plants was investigated using energy and exergy analyses, in design and off-design conditions using real weather data obtained from the Presidency of Meteorology and Environment in Saudi Arabia. Two different desalination technologies and two different coupling techniques were examined in four proposed plants. An optimal plant design was chosen from a comparison between all proposed plants' energy and exergy analysis results. The chosen plant was then optimized and simulated in design and off-design conditions. The initial results indicated that the simulated combined power plant's carbon footprint was reduced by 36.8% and its energy utilization factor was improved by 30.97%. This approach also stabilized the effect of ambient temperature fluctuations on the gas turbine's performance. After optimization, the carbon footprint was further reduced by 31.17% and the energy utilization factor was further improved by 6.11%. The energy destroyed through the exhaust stack was reduced by 78% and the proposed plant's overall exergetic efficiency was improved to 49.64%. Furthermore, the desalination plant's concentration factor was reduced by 0.45 and an additional product of a hot water stream at a temperature of 75°C was gained. An economic study was performed that indicated that the optimized plant is economically viable. As part of this analysis, a number of sensitivity studies defined the minimum selling prices of the plant's products and indicated the influence of fuel price, interest rates, capacity factors and project lifetime on the viability of the plant. The results also indicated that the proposed plant is a good investment, offering competitive energy and potable water prices, in regard to the location indicated by this study

Dynamic conversion of solar generated heat to electricity

The effort undertaken during this program led to the selection of the water-superheated steam (850 psig/900 F) crescent central receiver as the preferred concept from among 11 candidate systems across the technological spectrum of the dynamic conversion of solar generated heat to electricity. The solar power plant designs were investigated in the range of plant capacities from 100 to 1000 Mw(e). The investigations considered the impacts of plant size, collector design, feed-water temperature ratio, heat rejection equipment, ground cover, and location on solar power technical and economic feasibility. For the distributed receiver systems, the optimization studies showed that plant capacities less than 100 Mw(e) may be best. Although the size of central receiver concepts was not parametrically investigated, all indications are that the optimal plant capacity for central receiver systems will be in the range from 50 to 200 Mw(e). Solar thermal power plant site selection criteria and methodology were also established and used to evaluate potentially suitable sites. The result of this effort was to identify a site south of Inyokern, California, as typically suitable for a solar thermal power plant. The criteria used in the selection process included insolation and climatological characteristics, topography, and seismic history as well as water availability

The development of a hybrid simulator for power system control investigations

Imperial Users onl

Combustion system processes leading to corrosive deposits

Degradation of turbine engine hot gas path components by high temperature corrosion can usually be associated with deposits even though other factors may also play a significant role. The origins of the corrosive deposits are traceable to chemical reactions which take place during the combustion process. In the case of hot corrosion/sulfidation, sodium sulfate was established as the deposited corrosive agent even when none of this salt enters the engine directly. The sodium sulfate is formed during the combustion and deposition processes from compounds of sulfur contained in the fuel as low level impurities and sodium compounds, such as sodium chloride, ingested with intake air. In other turbine and power generation situations, corrosive and/or fouling deposits can result from such metals as potassium, iron, calcium, vanadium, magnesium, and silicon

Optimal design and operation of diesel cogeneration systems

Imperial Users onl

Operational simulation and an economical modelling study on utilizing waste heat energy in a desalination plant and an absorption chiller

It is well established that a large proportion of the global emission of greenhouse gases are produced by electricity power stations and that a power plant typically emits about two thirds of its input energy as waste heat into the atmosphere. As such there is a lot of potential for additional applications that utilize this waste heat energy. Utilizing this waste heat energy in a desalination plant to produce low-cost potable water is the key to overcoming three problems at once, namely the water shortage in and and semi-arid areas, the continuing increase in oil prices by being more efficient and global warming. In all waste heat recovery or alternative energy systems based on natural phenomena (solar or wind) a major difficulty is decoupling supply from demand as thermal storage is neither efficient nor practical in many cases. A significant difficulty of gas turbine based power generation systems is the derating caused by high ambient temperatures; typically a 1% change in ambient temperature produces a similar reduction in efficiency. Therefore, by also utilizing this waste heat energy in an absorption chiller to pre-cool the gas turbine's compressor inlet-air, the effect of ambient temperature fluctuations on the gas turbine's performance would be eliminated. The combined cycle described in this study was designed in an attempt to address these issues. A gas turbine based combined heat and power plant was combined further with an absorption refrigeration unit and an MED desalination plant. The absorption unit stabilizes the operation of the gas turbine, reducing the sensitivity to changes in ambient temperature and the desalination plant acts as an energy utilization device that produces a usable product (40,000m3/day of potable water) that is easily stored and distributed as required. The simulation was performed using IPSEpro on the basis of real data obtained from an existing power plant and commercially available plants. The performance of the sub-plants was investigated using energy and exergy analyses, in design and off-design conditions using real weather data obtained from the Presidency of Meteorology and Environment in Saudi Arabia. Two different desalination technologies and two different coupling techniques were examined in four proposed plants. An optimal plant design was chosen from a comparison between all proposed plants' energy and exergy analysis results. The chosen plant was then optimized and simulated in design and off-design conditions. The initial results indicated that the simulated combined power plant's carbon footprint was reduced by 36.8% and its energy utilization factor was improved by 30.97%. This approach also stabilized the effect of ambient temperature fluctuations on the gas turbine's performance. After optimization, the carbon footprint was further reduced by 31.17% and the energy utilization factor was further improved by 6.11%. The energy destroyed through the exhaust stack was reduced by 78% and the proposed plant's overall exergetic efficiency was improved to 49.64%. Furthermore, the desalination plant's concentration factor was reduced by 0.45 and an additional product of a hot water stream at a temperature of 75°C was gained. An economic study was performed that indicated that the optimized plant is economically viable. As part of this analysis, a number of sensitivity studies defined the minimum selling prices of the plant's products and indicated the influence of fuel price, interest rates, capacity factors and project lifetime on the viability of the plant. The results also indicated that the proposed plant is a good investment, offering competitive energy and potable water prices, in regard to the location indicated by this study.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Phase 1 of the First Small Power System Experiment (engineering Experiment No. 1). Volume 5: Supporting Analyses and Trade Studies

The development and design of a modular solar thermal power system for application in the 1 to 10 MWe range is described. The system is used in remote utility applications, small communities, rural areas, and for industrial uses. Thermal and stress analyses are performed on the collector subsystem, energy storage subsystem, energy transport subsystem, the power conversion subsystem, and the plant control subsystem

Study of Organic Rankine Cycles for Waste Heat Recovery in Transportation Vehicles

Regulations for ICE-based transportation in the EU seek carbon dioxide emissions lower than 95 g CO2/km by 2020. In order to fulfill these limits, improvements in vehicle fuel consumption have to be achieved. One of the main losses of ICEs happens in the exhaust line. Internal combustion engines transform chemical energy into mechanical energy through combustion; however, only about 15-32% of this energy is effectively used to produce work, while most of the fuel energy is wasted through exhaust gases and coolant. Therefore, these sources can be exploited to improve the overall efficiency of the engine. Between these sources, exhaust gases show the largest potential of Waste Heat Recovery (WHR) due to its high level of exergy. Regarding WHR technologies, Rankine cycles are considered as the most promising candidates for improving Internal Combustion Engines. However, the implementation of this technology in modern passenger cars requires additional features to achieve a compact integration and controllability in the engine. While industrial applications typically operates in steady state operating points, there is a huge challenge taking into account its impact in the engine during typical daily driving profiles. This thesis contributes to the knowledge and characterization of an Organic Rankine Cycle coupled with an Internal Combustion Engine using ethanol as working fluid and a swash-plate expander as expansion machine. The main objective of this research work is to obtain and quantify the potential of Organic Rankine Cycles for the use of residual energy in automotive engines. To do this, an experimental ORC test bench was designed and built at CMT (Polytechnic University of Valencia), which can be coupled to different types of automotive combustion engines. Using these results, an estimation of the main variables of the cycle was obtained both in stationary and transient operating points. A potential of increasing ICE mechanical efficiency up to 3.7% could be reached at points of high load installing an ORC in a conventional turbocharged gasoline engine. Regarding transient conditions, a slightly simple and robust control based on adaptive PIDs, allows the control of the ORC in realistic driving profiles. High loads and hot conditions should be the starting ideal conditions to test and validate the control of the ORC in order to achieve high exhaust temperatures that justify the feasibility of the system. In order to deepen in the viability and characteristics of this particular application, some theoretical studies were done. A 1D model was developed using LMS Imagine.Lab Amesim platform. A potential improvement of 2.5% in fuel conversion efficiency was obtained at the high operating points as a direct consequence of the 23.5 g/kWh reduction in bsfc. To conclude, a thermo-economic study was developed taking into account the main elements of the installation costs and a minimum Specific Investment Cost value of 2030 €/kW was obtained. Moreover, an exergetic study showed that a total amount of 3.75 kW, 36.5% of exergy destruction rate, could be lowered in the forthcoming years, taking account the maximum efficiencies considering technical restrictions of the cycle components.Las normativas anticontaminantes para el transporte propulsado por motores de combustión interna alternativos en la Unión Europea muestran límites de emisión menores a 95 g CO2/km para el año 2020. Con el fin de cumplir estos límites, deberán ser realizadas mejoras en el consumo de combustible en los vehículos. Una de las principales pérdidas en los Motores de Combustión Interna Alternativos (MCIA) ocurre en la línea de escape. Los MCIA transforman la energía química en energía mecánica a través de la combustión; sin embargo, únicamente el 15-32% de esta energía es eficazmente usada para producir trabajo, mientras que la mayor parte es desperdiciada a través de los gases de escape y el agua de refrigeración del motor. Por ello, estas fuentes de energía pueden ser utilizadas para mejorar la eficiencia global del vehículo. De estas fuentes, los gases de escape muestran un potencial mayor de recuperación de energía residual debido a su mayor contenido exergético. De todos los tipos de Sistemas de Recuperación de Energía Residual, los Ciclos Rankine son considerados como los candidatos más prometedores para mejorar la eficiencia de los MCIA. Sin embargo, la implementación de esta tecnología en los vehículos de pasajeros modernos requiere nuevas características para conseguir una integración compacta y una buena controlabilidad del motor. Mientras que las aplicaciones industriales normalmente operan en puntos de operación estacionarios, en el caso de los vehículos con MCIA existen importantes retos teniendo en cuenta su impacto en el modo de conducción cotidianos. Esta Tesis contribuye al conocimiento y caracterización de un Ciclo Rankine Orgánico acoplado con un Motor de Combustión Interna Alternativo utilizando etanol como fluido de trabajo y un expansor tipo Swash-plate como máquina expansora. El principal objetivo de este trabajo de investigación es obtener y cuantificar el potencial de los Ciclos Rankine Orgánicos (ORC) para la recuperación de la energía residual en motores de automoción. Para ello, una instalación experimental con un Ciclo Rankine Orgánico fue diseñada y construida en el Instituto Universitario "CMT - Motores Térmicos" (Universidad Politécnica de Valencia), que puede ser acoplada a diferentes tipos de motores de combustión interna alternativos. Usando esta instalación, una estimación de las principales variables del ciclo fue obtenida tanto en puntos estacionarios como en transitorios. Un potencial de mejora en torno a un 3.7 % puede ser alcanzada en puntos de alta carga instalando un ORC en un motor gasolina turboalimentado. Respecto a las condiciones transitorias, un control sencillo y robusto basado en PIDs adaptativos permite el control del ORC en perfiles de conducción reales. Las condiciones ideales para testear y validar el control del ORC son alta carga en el motor comenzando con el motor en caliente para conseguir altas temperaturas en el escape que justifiquen la viabilidad de estos ciclos. Para tratar de profundizar en la viabilidad y características de esta aplicación particular, diversos estudios teóricos fueron realizados. Un modelo 1D fue desarrollado usando el software LMS Imagine.Lab Amesim. Un potencial de mejora en torno a un 2.5% en el rendimiento efectivo del motor fue obtenido en condiciones transitorias en los puntos de alta carga como una consecuencia directa de la reducción de 23.5 g/kWh del consumo específico. Para concluir, un estudio termo-económico fue desarrollado teniendo en cuenta los costes de los principales elementos de la instalación y un valor mínimo de 2030 €/kW fue obtenido en el parámetro de Coste Específico de inversión. Además, el estudio exergético muestra que un total de 3.75 kW, 36.5 % de la tasa de destrucción total de exergía, podría ser reducida en los años futuros, teniendo en cuenta las máximas eficiencias considerando restricciones técnicas en los componentes del ciclo.Les normatives anticontaminants per al transport propulsat per motors de combustió interna alternatius a la Unió Europea mostren límits d'emissió menors a 95 g·CO2/km per a l'any 2020. Per tal d'acomplir aquests límits, s'hauran de realitzar millores al consum de combustible dels vehicles. Una de les principals pèrdues als Motors de combustió interna alternatius (MCIA) ocorre a la línia d'escapament. Els MCIA transformen l'energia química en energia mecànica a través de la combustió; però, únicament el 15-32% d'aquesta energia és usada per produir treball, mentre que la major part és desaprofitada a través dels gasos d'escapament i l'aigua de refrigeració del motor. Per això, aquestes fonts d'energia poden ser utilitzades per millorar l'eficiència global del vehicle. Considerant aquestes dues fonts d'energia, els gasos d'escapament mostren un potencial major de recuperació d'energia residual debut al seu major contingut exergètic. De tots els tipus de Sistemes de Recuperació d'Energia Residual, els Cicles Rankine són considerats com els candidats més prometedors per millorar l'eficiència dels MCIA. No obstant, la implementació d'aquesta tecnologia en els vehicles de passatgers moderns requereix un desenvolupament addicional per aconseguir una integració compacta i una bona controlabilitat del motor. Mentre que les aplicacions industrials normalment operen en punts d'operació estacionaris, en el cas dels vehicles amb MCIA hi han importants reptes a solucionar tenint en compte el funcionament en condicions variables del motor i el seu impacte en la manera de conducció quotidiana del usuari. Aquesta Tesi contribueix al coneixement i caracterització d'un Cicle Rankine Orgànic (ORC) acoblat amb un motor de combustió interna alternatiu (MCIA) utilitzant etanol com a fluid de treball i un expansor tipus Swash-plate com a màquina expansora. El principal objectiu d'aquest treball de recerca és obtenir i quantificar el potencial dels ORCs per a la recuperació de l'energia residual en motors d'automoció. Per aconseguir-ho, una instal·lació experimental amb un ORC va ser dissenyada i construïda a l'Institut "CMT- Motores Térmicos" (Universitat Politècnica de València). Esta installació pot ser acoblada a diferents tipus de MCIAs. Mitjançant assajos experimentals en aquesta installació, una estimació de les principals variables del cicle va ser obtinguda tant en punts estacionaris com en punts transitoris. Un potencial de millora al voltant d'un 3.7% pot ser aconseguida en punts d'alta càrrega instal·lant un ORC acoblat a un motor gasolina turboalimentat. Pel que fa a les condicions transitòries, un control senzill i robust basat en PIDs adaptatius permet el control del ORC en perfils de conducció reals. Les condicions ideals per a testejar i validar el control de l'ORC són alta càrrega al motor començant amb el motor en calent per aconseguir altes temperatures d'escapament que justifiquen la viabilitat d'aquests cicles. Per tractar d'aprofundir en la viabilitat i característiques d'aquesta aplicació particular, diversos estudis teòrics van ser realitzats. Un model 1D va ser desenvolupat usant el programari LMS Imagine.Lab Amesim. Un potencial de millora al voltant d'un 2.5% en el rendiment efectiu del motor va ser obtingut en condicions transitòries en els punts d'alta càrrega com una conseqüència directa de la reducció de 23.5 g/kWh al consum específic. Per concloure, un estudi termo-econòmic va ser desenvolupat tenint en compte els costos dels principals elements de la installació i un valor mínim de 2030 €/kW va ser obtingut en el paràmetre del Cost Específic d'Inversió. A més, l'estudi exergètic mostra que un total de 3.75 kW, 36.5% de la taxa de destrucció total d'exergia, podria ser recuperat en un pròxim, considerant restriccions tècniques en els components del cicle i tenint en compte les màximes eficiències que es poden aconseguir.Royo Pascual, L. (2017). Study of Organic Rankine Cycles for Waste Heat Recovery in Transportation Vehicles [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84013TESI

Conceptual design of thermal energy storage systems for near term electric utility applications. Volume 1: Screening of concepts

Over forty thermal energy storage (TES) concepts gathered from the literature and personal contacts were studied for their suitability for the electric utility application of storing energy off-peak discharge during peak hours. Twelve selections were derived from the concepts for screening; they used as storage media high temperature water (HTW), hot oil, molten salts, and packed beds of solids such as rock. HTW required pressure containment by prestressed cast-iron or concrete vessels, or lined underground cavities. Both steam generation from storage and feedwater heating from storage were studied. Four choices were made for further study during the project. Economic comparison by electric utility standard cost practices, and near-term availability (low technical risk) were principal criteria but suitability for utility use, conservation potential, and environmental hazards were considered