31 |
Model based control optimisation of renewable energy based HVAC SystemsPietruschka, Dirk January 2010 (has links)
During the last 10 years solar cooling systems attracted more and more interest not only in the research area but also on a private and commercial level. Several demonstration plants have been installed in different European countries and first companies started to commercialise also small scale absorption cooling machines. However, not all of the installed systems operate efficiently and some are, from the primary energy point of view, even worse than conventional systems with a compression chiller. The main reason for this is a poor system design combined with suboptimal control. Often several non optimised components, each separately controlled, are put together to form a ‘cooling system’. To overcome these drawbacks several attempts are made within IEA task 38 (International Energy Agency Solar Heating and Cooling Programme) to improve the system design through optimised design guidelines which are supported by simulation based design tools. Furthermore, guidelines for an optimised control of different systems are developed. In parallel several companies like the SolarNext AG in Rimsting, Germany started the development of solar cooling kits with optimised components and optimised system controllers. To support this process the following contributions are made within the present work: - For the design and dimensioning of solar driven absorption cooling systems a detailed and structured simulation based analysis highlights the main influencing factors on the required solar system size to reach a defined solar fraction on the overall heating energy demand of the chiller. These results offer useful guidelines for an energy and cost efficient system design. - Detailed system simulations of an installed solar cooling system focus on the influence of the system configuration, control strategy and system component control on the overall primary energy efficiency. From the results found a detailed set of clear recommendations for highly energy efficient system configurations and control of solar driven absorption cooling systems is provided. - For optimised control of open desiccant evaporative cooling systems (DEC) an innovative model based system controller is developed and presented. This controller consists of an electricity optimised sequence controller which is assisted by a primary energy optimisation tool. The optimisation tool is based on simplified simulation models and is intended to be operated as an online tool which evaluates continuously the optimum operation mode of the DEC system to ensure high primary energy efficiency of the system. Tests of the controller in the simulation environment showed that compared to a system with energy optimised standard control the innovative model based system controller can further improve the primary energy efficiency by 19 %.
|
32 |
Discrete and porous computational fluid dynamics modelling of an air-rock bed thermal energy storage systemLouw, Andre Du Randt 04 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Concentrating solar power promises to be a potential solution for meeting the
worlds energy needs in the future. One of the key features of this type of renewable
energy technology is its ability to store energy effectively and relatively
cheaply. An air-rock bed thermal energy storage system promises to be an effective
and reasonably inexpensive storage system for concentrating solar power
plants. Currently there is no such storage system commercially in operation
in any concentrating solar power plant, and further research is required before
such a system can be implemented. The main research areas to address are
the thermal-mechanical behaviour of rocks, rock bed pressure drop correlations
and effective and practical system designs. Recent studies have shown that the
pressure drop over a packed bed of rocks is dependant on various aspects such
as particle orientation relative to the flow direction, particle shape and surface
roughness. The irregularity and unpredictability of the particle shapes make it
difficult to formulate a general pressure drop correlation. Typical air-rock bed
thermal design concepts consist of a large vertical square or cylindrical vessel in
which the bed is contained. Such system designs are simple but susceptible to
the ratcheting effect and large pressure drops. Several authors have proposed
concepts to over-come these issues, but there remains a need for tools to prove
the feasibility of the designs.
The purpose of this paper is to investigate aDEM-CFD coupled approach that
can aid the development of an air-rock bed thermal energy storage system. This
study specifically focuses on the use of CFD. A complementary study focusses
on DEM. The two areas of focus in this study are the pressure drop and system
design. A discrete CFD simulation model is used to predict pressure drop over packed beds containing spherical and irregular particles. DEM is used to create
randomly packed beds containing either spherical or irregularly shaped particles.
This model is also used to determine the heat transfer between the fluid
and particle surface. A porous CFD model is used to model system design concepts.
Pressure drop and heat transfer data predicted by the discrete model, is
used in the porous model to describe the pressure drop and thermal behaviour
of a TES system.
Results from the discrete CFD model shows that it can accurately predict the
pressure drop over a packed bed of spheres with an average deviation of roughly
10%fromresults found in literature. The heat transfer between the fluid and particle
surface also is accurately predicted, with an average deviation of between
13.36 % and 21.83 % from results found in literature. The discrete CFD model for
packed beds containing irregular particles presented problems when generating
a mesh for the CFD computational domain. The clump logic method was used
to represent rock particles in this study. This method was proven by other studies
to accurately model the rock particle and the rock packed bed structure using
DEM. However, this technique presented problems when generating the surface
mesh. As a result a simplified clump model was used to represent the rock particles.
This simplified clump model showed characteristics of a packed bed of
rocks in terms of pressure drop and heat transfer. However, the results suggest
that the particles failed to represent formdrag. This was attributed to absence of
blunt surfaces and sharp edges of the simplified clumpmodel normally found on
rock particles. The irregular particles presented in this study proved to be inadequate
for modelling universal characteristics of a packed bed of rocks in terms of
pressure drop. The porous CFD model was validated against experimental measurement
to predict the thermal behaviour of rock beds. The application of the
porous model demonstrated that it is a useful design tool for system design concepts. / AFRIKAANSE OPSOMMING: Gekonsentreerde sonkrag beloof om ’n potensiële toekomstige oplossing te
wees vir die wêreld se groeiende energie behoeftes. Een van die belangrikste eienskappe
van hierdie tipe hernubare energie tegnologie is die vermoë om energie
doeltreffend en relatief goedkoop te stoor. ’n Lug-klipbed termiese energie
stoorstelsel beloof om ’n doeltreffende en redelik goedkoop stoorstelsel vir gekonsentreerde
sonkragstasies te wees . Tans is daar geen sodanige stoorstelsel
kommersieël in werking in enige gekonsentreerde sonkragstasie nie. Verdere navorsing
is nodig voordat so ’n stelsel in werking gestel kan word. Die belangrikste
navorsingsgebiede om aan te spreek is die termies-meganiese gedrag van klippe,
klipbed drukverlies korrelasies en effektiewe en praktiese stelsel ontwerpe. Onlangse
studies het getoon dat die drukverlies oor ’n gepakte bed van klippe afhanklik
is van verskeie aspekte soos partikel oriëntasie tot die vloeirigting, partikel
vormen oppervlak grofheid. Die onreëlmatigheid en onvoorspelbaarheid van
die klip vorms maak dit moeilik om ’n algemene drukverlies korrelasie te formuleer.
Tipiese lug-klipbed termiese ontwerp konsepte bestaan uit ’n groot vertikale
vierkantige of silindriese houer waarin die gepakte bed is. Sodanige sisteem
ontwerpe is eenvoudig, maar vatbaar vir die palrat effek en groot drukverliese.
Verskeie studies het voorgestelde konsepte om hierdie kwessies te oorkom, maar
daar is steeds ’n behoefte aanmetodes om die haalbaarheid van die ontwerpe te
bewys.
Die doel van hierdie studie is om ’n Diskreet Element Modelle (DEM) en numeriese
vloeidinamika gekoppelde benadering te ontwikkel wat ’n lug-klipbed termiese energie stoorstelsel kan ondersoek. Hierdie studie fokus spesifiek op
die gebruik van numeriese vloeidinamika. ’n Aanvullende studie fokus op DEM.
Die twee areas van fokus in hierdie studie is die drukverlies en stelsel ontwerp.
’n Diskrete numeriese vloeidinamika simulasie model word gebruik om drukverlies
te voorspel oor gepakte beddens met sferiese en onreëlmatige partikels.
DEM word gebruik om lukraak gepakte beddens van óf sferiese óf onreëlmatige
partikels te skep. Hierdie model is ook gebruik om die hitte-oordrag tussen die
vloeistof en partikel oppervlak te bepaal. ’n Poreuse numeriese vloeidinamika
model word gebruik omdie stelsel ontwerp konsepte voor te stel. Drukverlies en
hitte-oordrag data, voorspel deur die diskrete model, word gebruik in die poreuse
model om die drukverlies- en hittegedrag van ’n TES-stelsel te beskryf. Resultate van die diskrete numeriese vloeidinamikamodel toon dat dit akkuraat
die drukverlies oor ’n gepakte bed van sfere kan voorspel met ’n gemiddelde
afwyking van ongeveer 10%van die resultatewat in die literatuur aangetref word.
Die hitte-oordrag tussen die vloeistof en partikel oppervlak is ook akkuraat voorspel,
met ’n gemiddelde afwyking van tussen 13.36%en 21.83%van die resultate
wat in die literatuur aangetref word. Die diskrete numeriese vloeidinamika model
vir gepakte beddens met onreëlmatige partikels bied probleme wanneer ’n
maas vir die numeriese vloeidinamika, numeriese domein gegenereer word. Die
"clump"logika metode is gebruik om klip partikels te verteenwoordig in hierdie
studie. Hierdiemetode is deur ander studies bewys om akkuraat die klip partikel
en die klip gepakte bed-struktuur te modelleer deur die gebruik van DEM. Hierdie
tegniek het egter probleme gebied toe die oppervlak maas gegenereer is. As
gevolg hiervan is ’n vereenvoudigde "clump"model gebruik om die klip partikels
te verteenwoordig. Die vereenvoudigde "clump"model vertoon karakteristieke
eienskappe van ’n gepakte bed van klippe in terme van drukverlies en hitte oordrag.
Die resultate het egter getoon dat die partikels nie vorm weerstand verteenwoordig
nie. Hierdie resultate kan toegeskryf word aan die afwesigheid van
gladde oppervlaktes en skerp kante, wat normaalweg op klip partikels gevind
word, in die vereenvoudigde "clump"model. Die oneweredige partikels wat in
hierdie studie voorgestel word, blykomnie geskik tewees vir die modellering van
die universele karakteristieke eienskappe van ’n gepakte bed van klippe in terme
van drukverlies nie. Die poreuse numeriese vloeidinamika model is met eksperimentele
metings bevestig omdie termiese gedrag van klipbeddens te voorspel.
Die toepassing van die poreuse model demonstreer dat dit ’n nuttige ontwerp
metode is vir stelsel ontwerp konsepte.
|
33 |
Automatic positioner and control system for a motorized parabolic solar reflectorPrinsloo, Gerhardus Johannes 12 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Most rural African villages enjoy high levels of sunlight, but rolling out solar
power generation technology to tap into this renewable energy resource at remote
rural sites in Africa pose a number of design challenges. To meet these
challenges, a project has been initiated to design, build and test/evaluate a
knock down 3 kW peak electrical stand-alone self-tracking dual-axis concentrating
solar power system.
This study focusses on the mechatronic engineering aspects in the design
and development of a dynamic mechatronic platform and digital electronic
control system for the stand-alone concentrating solar power system. Design
specifications require an accurate automatic positioner and control system for
a motorized parabolic solar reflector with an optical solar harnessing capacity
of 12 kWt at solar noon. It must be suitable for stand-alone rural power generation.
This study presents a conceptual design and engineering prototype
of a balanced cantilever tilt-and-swing dual-axis slew drive actuation means
as mechatronic solar tracking mobility platform for a ∼12 m2 lightweight
parabolic solar concentrator. Digital automation of the concentrated solar
platform is implemented using an industrial Siemens S7-1200 programmable
logic controller (PLC) with digital remote control interfacing, pulse width modulated
direct current driving, and electronic open loop/closed loop solar tracking
control. The design and prototype incorporates off-the-shelf components
to support local manufacturing at reduced cost and generally meets the goal
of delivering a dynamic mechatronic platform for a concentrating solar power
system that is easy to transport, assemble and install at remote rural sites
in Africa. Real-time experiments, conducted in the summer of South Africa,
validated and established the accuracy of the engineering prototype positioning
system. It shows that the as-designed and -built continuous solar tracking
performs to an optical accuracy of better than 1.0◦ on both the azimuth and
elevation tracking axes; and which is also in compliance with the pre-defined
design specifications.
Structural aspects of the prototype parabolic dish are evaluated and optimized
by other researchers while the Stirling and power handling units are under
development in parallel projects. Ultimately, these joint research projects
aim to produce a locally manufactured knock down do-it-yourself concentrated
solar power generation kit, suitable for deployment into Africa. / AFRIKAANSE OPSOMMING: Landelike gebiede in Afrika geniet hoë vlakke van sonskyn, maar die ontwerp
van betroubare sonkrag tegnologie vir die benutting van hierdie hernubare
energie hulpbron by afgeleë gebiede in Afrika bied verskeie uitdagings. Om
hierdie uitdagings te oorkom, is ’n projek van stapel gestuur om ’n afbreekbare
3 kW piek elektriese alleenstaande selfaangedrewe dubbel-as son-konsentreeder
te ontwerp, bou en te toets.
Hierdie studies fokus op die megatroniese ingenieurs-aspekte in die ontwerp
en ontwikkeling van ’n dinamiese megatroniese platform en ’n digitale
elektroniese beheerstelsel vir die alleenstaande gekonsentreerde sonkrag stelsel.
Ontwerp spesifikasies vereis ’n akkurate outomatiese posisionering en beheer
stelsel vir ’n motor aangedrewe paraboliese son reflekteerder met ’n optiesekollekteer-
kapasiteit van 12 kWt by maksimum sonhoogte, en veral geskik wees
vir afgeleë sonkrag opwekking. Hierdie studie lewer ’n konsepsuele ontwerp en
ingenieurs-prototipe van ’n gebalanseerde dubbelas swaai-en-kantel swenkrat
aandrywingsmeganisme as megatroniese sonvolg platform vir ’n ∼12 m2 liggewig
paraboliese son konsentreerder. Digitale outomatisering van die son konsentreerder
platform is geimplementeer op ’n industriële Siemens S7-1200 programmeerbare
logiese beheerder (PLB) met ’n digitale afstandbeheer koppelvlak,
puls-wydte-gemoduleerde gelykstroom aandrywing en elektroniese ooplus
en geslote-lus sonvolg beheer. Die ontwerp en prototipe maak gebruik van
beskikbare komponente om lae-koste plaaslike vervaardiging te ondersteun en
slaag in die algemeen in die doel om ’n dinamiese megatroniese platform vir ’n
gekonsentreerde sonkrag stelsel te lewer wat maklik vervoer, gebou en opgerig
kan word op afgeleë persele in Afrika. Intydse eksperimente is gedurende die
somer uitgevoer om die akkuraatheid van die prototipe posisionering sisteem
te evalueer. Dit toon dat die sisteem die son deurlopend volg met ’n akkuraatheid
beter as 1.0◦ op beide die azimut en elevasie sonvolg asse, wat voldoen
aan die ontwerp spesifikasies.
Strukturele aspekte van die prototipe paraboliese skottel word deur ander
navorsers geëvalueer en verbeter terwyl die Stirling-eenheid en elektriese sisteme
in parallelle projekte ontwikkel word. Die uiteindelike doel met hierdie
groepnavorsing is om ’n plaaslik vervaardigde doen-dit-self sonkrag eenheid te
ontwikkel wat in Afrika ontplooi kan word.
|
34 |
Etude de défauts critiques des installations solaires thermiques de grande dimension : définition, modélisation et diagnostic / Study of large solar thermal system critical faults : definition, modelling and diagnosisFaure, Gaëlle 25 October 2018 (has links)
Les centrales solaires thermiques de grande dimension basse et moyenne température (80-120°C) peuvent fournir une chaleur renouvelable et compétitive aux réseaux de chaleurs et aux industries. Ces installations, intensives en capital et avec des faibles coûts de fonctionnement, ont un retour sur investissement sur le long terme. Le suivi de performance et la détection et le diagnostic de défauts automatisés sont donc des axes essentiels permettant de garantir des performances optimales sur toute la durée de vie de l’installation.Cette thèse a pour but l’analyse des défauts les plus importants, dans un but de détection et de diagnostic. Dans un premier temps, une étude exhaustive des défauts pouvant affecter les installations solaires thermiques a été réalisée. Cette étude a permis d’identifier les défauts les plus fréquents et les plus graves, autrement appelés défauts critiques. Parmi ces défauts, six ont été sélectionnés pour être étudiés plus en détails.Afin d’analyser le comportement du système lorsqu’il est soumis aux différents défauts étudiés, un modèle numérique a été mis en place. En particulier, un nouveau modèle de capteur solaire thermique plan a été développé, les modèles existants ne détaillant pas suffisamment certaines caractéristiques physiques nécessaires à la reproduction des défauts. Une validation expérimentale de ce modèle en fonctionnement normal et défaillant a montré qu’il permet une modélisation simple des défauts et que son comportement est réaliste.Une méthodologie pour analyser de façon numérique l’impact des défauts sur le comportement du système est ensuite proposée. Un ensemble de grandeurs permettant de caractériser ce comportement sont notamment définies. Cette méthodologie est ensuite appliquée, d’abord à l’échelle du composant directement impacté par le défaut, puis à l’échelle du système complet. Les résultats permettent d’identifier les défauts détectables ainsi que ceux qui sont identifiables et de proposer un ensemble réduit de grandeurs suffisant pour les détecter et les identifier.Ces travaux offrent une base méthodologique et des premiers résultats qui pourront permettre de développer un algorithme automatisé pour détecter et diagnostiquer les défauts critiques d’une installation solaire thermique de grande dimension. / Large scale solar systems at low and medium temperature (80-120 °C) can provide renewable and competititve energy to district heating and industrial processes. These systems, which are capital-intensive and have low operating costs, present a long-term return on investment. Automated monitoring and fault detection and diagnosis are key elements to guarantee optimal performances during all the lifespan of the plant.This dissertation aims to analyze of the main faults, in a detection and diagnosis purpose. First, an exhaustive study of the dysfunctions that can affect the large scale solar systems enabled to identify the more frequent and serious faults, also called critical faults. Among these critical faults, six were selected for a more detailed study.To analyze the behavior of the system subjected to the studied faults, a numerical model was implemented. A new flat plate thermal solar collector model was particularly developed as existing ones do not detail enough several physical characteristics required for the reproduction of faults. An experimental validation of this model in normal and faulty operation showed that it enables a simple fault modelling and presents a realistic behavior.A methodology to numerically analyze the impact of the faults on the system behavior is then proposed. A set of features enabling the characterizing of this behavior are particularly defined. This approach is applied first at the scale of directly affected component then at system scale. The results enable to identify detectable and isolable faults, but also to propose a reduced set of features sufficient to properly detect and diagnose them.This work presents a methodologic base and first results to develop an automated algorithm for detection and diagnosis of critical faults of a large scale thermal solar system.
|
35 |
A NOVEL SOLAR THERMAL MEMBRANE DISTILLATION SYSTEM FOR DRINKING WATER PRODUCTION IN UNDEVELOPED AREASUnknown Date (has links)
In this research, a heat localizing solar thermal membrane distillation system has been developed for producing potable water from untreated surface water, wastewater, and seawater, using solely solar thermal energy. Unlike most other membrane technologies, this system requires no electrical power or equipment for its operation. The high production rate was achieved through the effective evaporation of water molecules within the pores of the membrane without dissipating much heat to the bulk feed water. It can remove suspending particles, microorganisms, inorganic salts, as well as organic contaminants from the feed water. The system can produce potable water for 32, 18, and 10 days on average under simulated sunlight when distilling seawater, canal water, and municipal wastewater, respectively, without cleaning the membrane. Low cost, high energy efficiency (i.e., 55%), and good water quality make the new system feasible for undeveloped areas where basic water treatment is lacking. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection
|
36 |
Hybrid Solar Gas-Turbine Power Plants : A Thermoeconomic AnalysisSpelling, James January 2013 (has links)
The provision of a sustainable energy supply is one of the most importantissues facing humanity at the current time, and solar thermal power hasestablished itself as one of the more viable sources of renewable energy. Thedispatchable nature of this technology makes it ideally suited to forming thebackbone of a future low-carbon electricity system.However, the cost of electricity from contemporary solar thermal power plantsremains high, despite several decades of development, and a step-change intechnology is needed to drive down costs. Solar gas-turbine power plants are apromising new alternative, allowing increased conversion efficiencies and asignificant reduction in water consumption. Hybrid operation is a furtherattractive feature of solar gas-turbine technology, facilitating control andensuring the power plant is available to meet demand whenever it occurs.Construction of the first generation of commercial hybrid solar gas-turbinepower plants is complicated by the lack of an established, standardised, powerplant configuration, which presents the designer with a large number ofchoices. To assist decision making, thermoeconomic studies have beenperformed on a variety of different power plant configurations, includingsimple- and combined-cycles as well as the addition of thermal energy storage.Multi-objective optimisation has been used to identify Pareto-optimal designsand highlight trade-offs between costs and emissions.Analysis of the simple-cycle hybrid solar gas-turbines revealed that, whileelectricity costs were kept low, the achievable reduction in carbon dioxideemissions is relatively small. Furthermore, an inherent trade-off between thedesign of high efficiency and high solar share hybrid power plants wasidentified. Even with the use of new optimised designs, the degree of solarintegration into the gas-turbine did not exceed 63% on an annual basis.In order to overcome the limitations of the simple-cycle power plants, twoimprovements were suggested: the integration of thermal energy storage, andthe use of combined-cycle configurations. Thermal energy storage allowed thedegree of solar operation to be extended, significantly decreasing carbondioxide emissions, and the addition of a bottoming-cycle reduced the electricitycosts. A combination of these two improvements provided the bestperformance, allowing a reduction in carbon dioxide emissions of up to 34%and a reduction in electricity costs of up to 22% compared to a combination ofconventional power generation technologies. / Hållbar energiförsörjning är för närvarande en av de viktigaste frågorna förmänskligheten. Koncentrerad solenergi är nu etablerad som en tillförlitlig källaav förnybar energi. Den reglerbara karaktären hos tekniken gör den specielltintressant för uppbyggnaden av ett framtida koldioxidsnålt elsystem.Kostnaden för elektricitet från nuvarande termiska solkraftverk är hög trottsflera decennier av utveckling. Ett genombrått på tekniknivå krävs för att drivaned kostnaderna. Sol-gasturbiner är ett av de mest lovande alternativen, somger en ökad verkningsgrad samtidigt som vattenkonsumtionen reducerasdrastiskt. Sol-gasturbintekniken gör det möjligt att blandköra solenergi ochandra bränslen för att möta efterfrågan vid alla tidpunkter, en attraktiv aspekt iförhållande till alternativa lösningar.Uppbyggnaden av första generationens kommersiella hybrida solgasturbinkraftverkförsvåras dock av bristen på etablerade och standardiseradekraftverkskonfigurationer. Dessa ger planeraren ett stort antal valmöjlighetersom underlag för beslutsfattande. Termoekonomiska studier har genomförtsför ett flertal olika kraftverkskonfigurationer, däribland kraftverk med enkelcykel, kombikraftverk samt möjligheten att utnyttja termisk energilagring.Pareto-optimala konfigurationer har identifierats med hjälp av multiobjektsoptimeringför att belysa balansen mellan kostnader och utsläpp.Analysen av det enkla hybrida sol-gasturbinkraftverket visade attelektricitetskostnaden hållits på en låg nivå, men att den möjliga minskningen avkoldioxidutsläpp är relativt liten. Dessutom identifierades en inre balans mellanatt bibehålla en hög verkningsgrad hos konfigurationen och en hög andelsolenergi i produktionen. Andelen av solenergi i gasturbinen överskred aldrig63% på årlig bas, även med optimerade kraftverkskonfigurationer.Två förbättringar föreslås för att övervinna begränsningarna hos kraftverk medenkel cykel: integration av termisk energilagring samt nyttjande avkombikraftverkskonfigurationer. Termisk energilagring tillåter en ökad andelsolenergi i driften och reducerar koldioxidutsläppen drastiskt, medan denytterligare cykeln hos kombikraftverket reducerar elektricitetskostnaden.Kombinationen av dessa förbättringar ger den bästa prestandan, med enreduktion av koldioxidutsläppen på upp till 34% och reducerade elektricitetskostnaderpå upp till 22% i jämförelse med andra kombinationer avkonventionella kraftverkskonfigurationer. / <p>QC 20130503</p>
|
37 |
Simulations Of A Large Scale Solar Thermal Power Plant In Turkey Using Concentrating Parabolic Trough CollectorsUsta, Yasemin 01 December 2010 (has links) (PDF)
In this study, the theoretical performance of a concentrating solar thermal electric system (CSTES) using a field of parabolic trough collectors (PTC) is investigated. The commercial software TRNSYS and the Solar Thermal Electric Components (STEC) library are used to model the overall system design and for simulations. The model was constructed using data from the literature for an existing 30-MW solar electric generating system (SEGS VI) using PTC&rsquo / s in Kramer Junction, California. The CSTES consists of a PTC loop that drives a Rankine cycle with superheat and reheat, 2-stage high and 5-stage low pressure turbines, 5-feedwater heaters and a dearator. As a first approximation, the model did not include significant storage or back-up heating. The model&rsquo / s predictions were benchmarked against published data for the system in California for a summer day. Good agreement between the model&rsquo / s predictions and published data were found, with errors usually less than 10%. Annual simulations were run using weather data for both California and Antalya, Turkey. The monthly outputs for the system in California and Antalya are compared both in terms of absolute monthly outputs and in terms of ratios of minimum to maximum monthly outputs. The system in Antalya is found to produce30 % less energy annually than the system in California. The ratio of the minimum (December) to maximum (July) monthly energy produced in Antalya is 0.04.
|
38 |
An optimization model for a solar hybrid water heating and adsorption ice-making systemYeung, King-ho., 楊景豪. January 2003 (has links)
published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy
|
39 |
Central Solar Heating Plants with Seasonal Storage for Residential Applications in Canada: A Case Study of the Drake Landing Solar CommunityWamboldt, JASON 03 February 2009 (has links)
In Canada, 20% of greenhouse gas (GHG) emissions result from burning fossil fuels to heat homes, buildings, and water. Solar thermal technologies convert the sun’s energy into emission-free heat. The Drake Landing Solar Community (DLSC) in Okotoks, Alberta uses a Central Solar Heating Plant (CSHP) with Seasonal Storage to achieve an astounding annual reduction of 89 % in fossil fuel consumption and more than 5 tonnes in GHG emissions per home.
This thesis examines: (1) the role for solar thermal technologies in Canada; and (2) what social, economical, and environmental factors are critical to the implementation and ultimate success of the DLSC. The former was examined through a literature review and the latter through a qualitative case study. Data was collected from published articles, media reports, conference proceedings, and in-person interviews in Okotoks.
International markets have shown strong solar thermal growth, yet Canada lags significantly despite its powerful solar resources and readily available technology. Europe has demonstrated that strong policies with ambitious targets have a critical role in the implementation of solar technologies. A review of recent public opinion polls demonstrates Canadians value the environment and would favour such policy developments.
The case study sought to understand the roles and motivations of the municipality, home builder group, and homeowners. The municipality exhibited tremendous leadership when it embarked on a path towards sustainability that included controlled growth based on ecological limitations and investment in solar thermal technology for municipal buildings. The Federation of Canadian Municipalities was instrumental in exposing Okotoks and the home builder group to the CSHP successes in Europe. The flexibility and innovation of the home builder group provided conventionally-styled homes, which were able to seamlessly incorporate the technologies of the DLSC.
For the homeowners, critical components of the success of the project included: a means to participate in environmental change, increased community cohesion due to aligned values; and price stability for their heating costs. Additionally, all of the homeowners interviewed stated that they would be willing to pay extra to support the technology, which indicates that future projects may require less subsidization. / Thesis (Master, Environmental Studies) -- Queen's University, 2009-02-03 14:08:18.825
|
40 |
Experimental Analysis of an Indirect Solar Assisted Heat Pump for Domestic Water HeatingBRIDGEMAN, Andrew George 13 October 2010 (has links)
Due to rising energy costs and increasing environmental awareness, various methods of energy conservation are being investigated. In the residential sector, both solar and heat pump systems have been extensively tested. Recently, combinations of solar and heat pump systems have been developed for both space heating and water heating. These systems have the capability to provide better performances than either of the systems operating on their own. The solar collector benefits from a lower fluid (glycol) inlet temperature which increases efficiencies, and the heat pump benefits from higher evaporator temperatures due to the additional solar energy collected.
For this study, a prototype of an Indirect-Solar Assisted Heat Pump for use in the Canadian environment was constructed, instrumented and tested. Controlled, constant temperature tests, as well as solar profile tests were conducted and the heat transfer rates, natural convection flow rate, and heat pump coefficient of performance (COP) were calculated. These values were then compared to simulation results based on a model developed in a previous feasibility study. The experimental COPs calculated ranged from 2.3 to 3.3 throughout the full range of tests which were conducted with supply temperatures ranging from 0°C – 40°C. The simulated results consistently overestimated the experimental results by between 12% - 15%. New empirical heat exchanger relationships were developed for the model bringing the simulated results within 5% of the experimental results for tests run at glycol flow rates of 77 and 154 kg/hr. These relationships were used to refine the model, and produce updated annual performance values in the TRNSYS simulation software. Updated results showed a 5% drop in the annual free energy ratio in Toronto from 57% to 52%, but further optimization of the system using the TRNSYS software package improved annual results up to 56%.
For the purposes of the study, a solar assisted heat pump prototype was constructed and tested successfully within the laboratory environment. Results showed that the system has a strong market potential, especially in regions without a strong solar resource. Based on these results further research is recommended, continuing with a full year outdoor test using unglazed solar collectors. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-10-12 18:53:01.189
|
Page generated in 0.1044 seconds