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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

HEAT CONSUMPTION OPTIMIZATION IN 4TH GENERATION DISTRICT HEATING : Study on utilizing low temperature heat sources and heat stored in a house by varying indoor temperature

Karlsson, Simon, Farman, Farman January 2023 (has links)
4th generation district heating (4GDH) and varying the indoor temperature to store heat are both important concepts that can make it easier to implement more renewable energy and reduce costs of heating. This study looks at these concepts from a customer perspective using one building and looking at how energy can be stored and the performance of 4GDH. Low temperature heat sources from industry, supermarkets, and datacentres are used in combination with heat from a combined heat and power plant to get the required heating. A heat pump has also been modelled as a part of the 4GDH structure. In addition to looking at heat storage in 4GDH a scenario with direct electric heating has also been evaluated. In conclusion 4GDH has lower operating costs than 3rd generation district heating, but it is not worth varying the indoor temperature to store energy when using 4GDH. It is, however, profitable to vary indoor temperature if direct electric heating is used.
12

Nozzle Guide Vane Sweeping Jet Impingement Cooling

Agricola, Lucas 12 October 2018 (has links)
No description available.
13

Studie om värmetröghetens påverkan i tunga och lätta byggnader : Med avseende på energianvändning och branschens uppfattning / A study about the impact of thermal inertia in heavy and light buildings : Regarding the energy consumption and the industries perception

Lanneld, Jakob, Quick, Jennifer January 2022 (has links)
Detta arbete är en jämförelsestudie mellan tunga och lätta byggnader med avseende på värmetröghetens påverkan på energianvändning. Studien syftar sig även till att ta reda på uppfattningen samt användning av värmetröghet av olika yrkesroller inom byggbranschen. Då åsikterna och forskningen skiljer sig åt i branschen finns det inget direkt svar på hur mycket värmetröghet faktiskt påverkar energianvändningen. Då energi- och klimatkrisen är ett faktum i Sverige så måste energianvändningen samt klimatavtrycket som byggsektorn står för att minska, inte minst under produktion utan under hela livscykeln.  Studien ska besvara följande frågeställningar; hur använder och uppfattar olika aktörer i byggbranschen värmetröghet i tunga respektive lätta byggnader, hur skiljer sig energiförbrukningen i lätta respektive tunga byggnader för olika byggnadstyper? Värmetröghet är en byggnads förmåga att lagra värmen och är ett mått på dess termiska stabilitet. I denna studie är det följande byggnadstyper som undersöks: kontorsbyggnader och flerfamiljshus med tung och lätt stomme som är både välisolerad och dåligt isolerad. Studien började med en mindre litteraturgenomgång för att få en djupare och bredare förståelse för ämnet värmetröghet. Det två metoder som används under arbetet är semistrukturerade intervjuer och beräkningar i programmet BIM-Energy. Det har utförts sex intervjuer där yrkesrollerna varierade från konstruktör till affärsutvecklingschef. Intervjuerna varade i cirka 30 minuter och alla intervjuer följde samma intervjumall. I BIM-Energy modelleras åtta olika byggnader där fyra är kontor och fyra är flerfamiljshus. Av de fyra kontoren är två byggda i lätt konstruktion och två i tung konstruktion, desamma gäller för de fyra flerfamiljshusen. Kontoren och flerfamiljshusen konstruerades med en tung välisolerad byggnad samt en tung dåligt isolerad, detta gällde även för lätta konstruktionerna.  Värmetrögheten påverkade energianvändningen i kontorsbyggnaderna mer än i flerfamiljshusen. I kontoren minskade energianvändningen i alla modeller med en tung stomme jämfört med den lätta. I flerfamiljshusen minskade energianvändningen endast för den välisolerade tunga stommen och då var minskningen inte så markant. Kylbehovet minskade för de tungt konstruerade byggnaderna oavsett isoleringsmängd. Inomhustemperaturen varierade mindre för de tungt konstruerade byggnaderna än för de lätta.  Uppfattningen från de olika yrkesrollerna i byggbranschen var att värmetröghet i stommen inte påverkar energianvändningen markant och att ingen av de intervjuade använde det aktivt i sitt arbete. Slutsatsen blir då att byggbranschen inte använder värmetröghet vid dimensionering av stommar. För de beräknade resultatet blev slutsatsen att byggnadstypen är en viktig aspekt för att kunna använda värmetröghet i stommen på effektivt sätt för att minska energianvändningen. I detta fall är det kontor som är mer lämpade för det än flerfamiljshus. / This is a study comparing light and heavy buildings regarding the buildings thermal inertia and how that effects the energy use. The study also investigates the opinion and usage of thermal inertia from different professions in the building industry. The climate- and energy crisis is a fact in Sweden and the building sector needs to decrease its energy use and environmental footprint, not only in the construction face but the throughout the whole life cycle.  The two methods used in this study is semi-structured interviews and calculations in the program BIM-Energy. There were six interviews and the responders varied between building engineer and a business developing manger. The models consist of eight different buildings, four offices, were two are with heavy construction and two with light construction, with both high and low insolation. The other four buildings were modeled the same way, but the buildings area of use was apartments.  The results were that the energy consumption did decrease in the office buildings for the heavy construction compared to the light. The apartments did not significantly decrease in energy consumption and therefore the conclusion is that the usage of the building is an important factor in making a building use less energy with thermal inertia. The results from the interviews were that they did not use thermal inertia when dimensioning the buildings, but thermal inertia did decrease the energy consumption, but the amount of decrease was not agreed upon. The conclusion is that the building sector have different perception about how much the thermal inertia does affect the energy usage but also that the building sector does not use it when dimensioning a building.
14

Imagerie infrarouge thermique haute résolution : potentiels et limitations pour la géologie / High resolution thermal infrared imaging : potential and limitations for earth sciences

Gaudin, Damien 12 July 2012 (has links)
Le rayonnement infrarouge thermique (7.5-14 μm) permet de mesurer à distance la température de surfaces géologiques. Les capteurs de type “microbolomètre”, de bas prix et d’utilisation facile, sont de plus en plus utilisés pour cartographier sur le terrain des anomalies de température. Cependant, des phénomènes tels que l’opacité de l’atmosphère et les réflexions de la surface viennent modifier le signal. De plus, les images doivent être ajustées géométriquement pour être cartographiées. Après avoir proposé un protocole de correction géométrique et radiométrique des mesures, et quantifié les incertitudes résiduelles, quelques exemples sont étudiés pour définir les potentiels et les limites de l’infrarouge thermique en sciences de la Terre. Son potentiel pour la détection de la ligne de rivage a été utilisé lors d’une marée montante pour reconstituer le modèle numérique de terrain (MNT) d’une plage de l’Aber Benoît (Bretagne). D’autre part, un modèle informatique a été développé pour mesurer l’influence de la rugosité sur la température de la surface des planètes. Il a été appliqué au calcul de l’inertie thermique de Mars et de l’astéroïde (2867) Šteins. Enfin, les images infrarouges sont utilisées pour quantifier le flux de chaleur d’une zone sub-fumerollienne de la Soufrière. Ainsi, l’imagerie thermique infrarouge montre un fort potentiel, partiellement inexploité par les études actuelles, notamment pour la cartographie quantitative des contrastes de température à haute résolution. A haute fréquence, elle permet d’étudier la dynamique des phénomènes géologiques. / Thermal infrared (7.5-14 μm) enables the measurement of temperature far fromgeological surfaces. Microbolometers devices are increasingly used in the field in order to mapthermal anomalies. However, phenomena such as atmospheric opacity and surface reflections disturb the electromagnetic signal. In addition, images have to be geometrically adjusted to fit with geographical models. A processing chain is here suggested in order to correct the radiometry and the geometry of images, and the uncertainties are computed. Then, its potential and limitations are considered, through a few examples. First, it has been used in order to detect the waterline evolution of a mud shore during a rising tide, which enables to reconstruct a digital elevation model. Then, a computer model has been developed to study the roughness effects on the surface temperature and on the thermal inertial calculation on Mars and on the (2867) Šteins asteroid. Finally the heat flux of a sub-fumarolian zone has been computed in La Soufrière volcano (Guadeloupe, Lesser Antilles).Thus, thermal infrared remote sensing is very useful in quantitatively mapping the temperatures anomalies with a high resolution. High frequency studies should enable the survey of geological phenomena.
15

Paredes trombe no Brasil: análise do potencial de utilização para aquecimento e refrigeração / Trombe walls in Brazil: analysis of feasibility of use for heating and cooling

Cavalcanti, Fernando Antonio de Melo Sá 13 November 2013 (has links)
Neste trabalho avaliou-se o desempenho térmico de um ambiente padrão a partir do uso de parede trombe com diferentes configurações e tipologias de uso, por meio de comparação com um ambiente de mesmas dimensões dotado de janelas convencionais, para oito cidades brasileiras, pois o potencial de utilização desta forma de estratégia passiva ainda é pouco estudado no Brasil. A parede trombe consiste em uma \"estufa\" entre uma parede de alta inércia térmica com aberturas inferiores e superiores e uma superfície envidraçada por onde o ambiente mantém contato com o exterior. Este dispositivo é capaz de absorver energia proveniente da radiação solar aquecendo o ar nesta estufa e este ar aquecido pode ser direcionado para o interior ou exterior da edificação a depender da finalidade. Este ar pode ser usado para aquecer o ambiente ou resfriá-lo por meio da ventilação natural. A análise deste trabalho se deu a partir de uma série de simulações computacionais utilizando o software EnergyPlus, versão 7.0 de modo a quantificar e classificar o desempenho térmico de um ambiente padrão dotado deste componente, sob as diversas configurações construtivas. Tanto para aquecimento quanto para resfriamento dos ambientes. A partir destas simulações, elaborou-se um modelo matemático simplificado capaz de quantificar a temperatura do ar no interior dos ambientes em que sejam utilizadas as paredes trombe de modo a tornar possível a utilização deste dispositivo na composição de edificações na fase de projeto, estimando seu desempenho sem que haja necessidade de novas simulações computacionais. O uso das paredes trombe melhorou o conforto térmico dos usuários em edificações localizadas no Brasil, a depender do clima onde estão inseridas, promovendo ventilação natural e aquecimento solar passivo, mesmo quando comparado com o modelo convencional de aberturas. Por fim foi elaborado um aplicativo para sistema Android em dispositivos móveis, possibilitando aos profissionais de projeto identificar a melhor tipologia para a localidade onde se deseja inserir este sistema e prever seu desempenho, contribuindo para que o potencial deste dispositivo seja investigado nas mais diversas regiões brasileiras. / This research evaluated the thermal performance of a standard environment from the use of Trombe wall with different settings and types of use, by comparison with a setting of the same dimensions equipped with conventional windows for eight Brazilian cities, because the potential the utilization of this passive strategy is still little studied in Brazil. A Trombe wall consists of a \"greenhouse\" between a wall of high thermal inertia lower and upper vents and a glazed area where the environment keeps contact with the outside. This device is capable of absorbing energy from solar radiation heating the air this greenhouse and this heated air can be directed to the interior or exterior of the building depending on the purpose. This air can be used to heat the room or cool it by means of natural ventilation. The analysis of this work was made from a series of computer simulations using EnergyPlus software, version 7.0 in order to quantify and classify the thermal performance of a standard environment with this component, under the various construction settings. Both for heating and for cooling environments. From these simulations, we elaborated a simplified mathematical model able to measure the air temperature within the environments in which they are used Trombe walls in order to make use of this device in the composition of buildings in the design stage as possible, estimating its performance without the need for new computer simulations. The use of Trombe walls improved thermal comfort of users in buildings located in Brazil, depending on the climate where they are located , providing natural ventilation and passive solar heating, even when compared with the conventional model of openings. Finally an app for Android system for mobile devices was developed, enabling professionals to identify the best design type to the location where you want to enter this system and predict its performance, contributing to the potential of this device is investigated in several Brazilian regions.
16

Non-destructive Examination Of Stone Masonry Historic Structures-quantitative Ir Thermography And Ultrasonic Velocity

Akevren, Selen 01 March 2010 (has links) (PDF)
The in-situ examination of historical structures for diagnostic and monitoring purposes is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. The methods of quantitative infrared thermography (QIRT) and ultrasonic testing have distinct importance in this regard. The key concern of the study was developing the in-situ use of QIRT for assessment of stone masonry wall sections having different sublayer(s) and failures. For that purpose, the non-destructive in-situ survey composed of QIRT and ultrasonic testing was conducted on a 16th century monument, Cenabi Ahmet PaSa Camisi, suffering from structural cracks, dampness problems and materials deterioration. The combined use of these two methods allowed to define the thermal inertia characteristics of structural cracks in relation to their depth. The temperature evolution in time during the controlled heating and cooling process was deployed for the cracks/defects inspection. The superficial and deep cracks were found to have different thermal responses to exposed conditions which made them easily distinguishable by QIRT analyses. The depth of cracks was precisely estimated by the in-situ ultrasonic testing data taken in the indirect transmission mode. The inherently good thermal resistivity of the wall structure was found to have failed due to entrapped moisture resulting from incompatible recent plaster repairs. The IRT survey allowed to detect the wall surfaces with different sublayer configurations due to their different thermal inertia characteristics. The knowledge and experience gained on the experimental set-ups and analytic methods were useful for the improvement of in-situ applications of QIRT and ultrasonic testing.
17

Thermal mass applications in the hot‐humid region of Austin, TX

Kerbacher, Mariel Elizabeth 17 February 2011 (has links)
Thermal mass can be successfully implemented in the hot‐humid region of Austin, TX especially when well designed and with supplementary aids like nightcooling and day‐lighting. This study shows that in some situations thermal mass can be actually more beneficial at reducing electricity demands in hot‐humid regions than in the hot‐dry regions that are so emphasized in the literature. / text
18

Amélioration du confort d'été dans des bâtiments à ossature par ventilation de l'enveloppe et stockage thermique / Summer confort improvement in wooden frame building by wall and roof ventilation and thermal storage

Brun, Adrien 26 January 2011 (has links)
Depuis quelques années, d'importants efforts ont été réalisés sur l'amélioration de la performance énergétique des bâtiments qui représentent le premier poste de consommation énergétique en France. Les exigences de la nouvelle réglementation thermique 2012 illustrent bien ces évolutions avec une consommation conventionnelle d'énergie primaire comprenant l'ensemble des postes (chauffage, climatisation, éclairage, ventilation, eau chaude sanitaire), déduction faite de l'électricité produite sur place, qui devra être inférieure à 50 kWh.m2.an-1 d'énergie primaire. La réponse à cette nouvelle exigence se fera par l'adoption de technologies constructives conduisant à une consommation pour le chauffage équivalente aux constructions dites « passives » (environ 15 kWh.m2.an-1) et dont le recours à la climatisation est limité voir inexistant. Il s'agit pour cela de limiter toutes les contributions à l'échauffement du bâtiment et éventuellement de lui adjoindre un système de rafraichissement à coefficient de performance élevé. Après avoir montré par l'exemple qu'un bâtiment à ossature à faible inertie en métropole, par sa capacité de stockage thermique limitée, est prédisposé à des problèmes de surchauffe, nous avons construit cette thèse autour de deux axes d'amélioration, dédiés aux constructions à ossature, que sont : - La limitation des charges solaires transmises au travers de l'enveloppe en faisant appel à une spécificité des constructions à ossature qu'est la présence d'un espace naturellement ventilé en sous-face du parement extérieur que nous utiliserons afin d'extraire une partie des charges solaires incidentes; - Le couplage de ces bâtiments « légers » à un échangeur air/masse qui contient l'inertie nécessaire au maintien des conditions de confort estivales lorsque la réduction de température nocturne le permet. Basée sur une approche numérique et expérimentale en vrai grandeur et en conditions réelles, nous proposons d'aborder tour à tour chacune de ces stratégies d'amélioration du confort qui trouvent leurs applications aussi bien en climat chaud et sec qu'en climat tropical. / Building sector is the most important energy consumer in France, and one of the field where there is the highest potential for improvement. In recent years, building energy consumption has been the subject of continuously up-dated regulations aimed at reducing its impact. As an example, the latest national thermal regulation (RT 2012) makes it compulsory to respect the limits previously introduced by RT 2005 as a voluntary label, corresponding to the definition of guil{Low energy consumption buildings} (BBC); in order to get such a label, a building should have a primary energy consumption lower than 50 kWh.m2.an-1, calculated by making a balance between consumptions (heating, cooling, domestic hot water, lighting, ventilation) and local electricity production. In order to respond to this new requirement, appropriate architectural and technological solutions have to be used. As a results, heating needs should be limited to approximately 15 kWh.m2.an-1 - by improving the building insulation or by adopting passive solar techniques - and summer thermal comfort should be achieved with a minimum primary energy waste. Therefore, internal heat gains and external solar transmission must be limited and, if necessary, low energy cooling systems could be used. In the present work, we firstly studied the case of a low thermal inertia building. The simulation results show that this construction typology is subject to uncomfortable temperature swing. Afterwards, two propositions leading to the improvement of summer thermal comfort were developed. The first, dedicated to warm and humid climates, consists in limiting solar transmission through the wall by using a gap, generally integrated in a timber frame structure, to eliminate part of the absorbed heat by means of natural ventilation. Then, the increase of the building thermal inertia through the association of an air/mass storage system was assessed, which is especially suitable in warm and dry climates. Both propositions were based both on numerical studies and on experimentation performed on a full-scale test rig installed at CSTB (Scientific and Technical Centre for Building research).
19

Värmereglering utifrån byggnadens tidskonstant i en värmetrög fastighet : Prognostiseringar utav värmeenergianvändningen och dess ekonomiska kostnader

Berner Wik, Petter January 2018 (has links)
För att pådriva utvecklingen mot ett mer hållbart Gävle kommer Gävle Energi AB implementera en ny säsongsbaserad kapacitetsmodell ifrån årsskiftet 2019. Som ska skapa ekonomiska incitament för energieffektivisering i fastigheter inom Gävles fjärrvärmenät. Denna studie kartlägger värmeenergianvändningen i en fastighet som riskerar en förhöjd totalkostnad för fjärrvärmen till följd av den nya prismodellen. Målet med studien är att reducera värmeenergianvändningen utan att investera i fastigheten, vilket möjliggörs genom att värmeenergitillförseln till fastigheten regleras. Genom att programmera ett års historisk data av temperaturer, solinstrålning, el- och värmeeffekter så prognostiseras värmetillförseln på samma sätt som fastighetens styrsystem Kabona Eco-pilot. Styrsystemet tillämpar en flytande inomhustemperatur vilket bidrar till att fastighetens värmetröghet inkluderas i värmeregleringen. Studien inkluderar två prognoser som jämförs med den verkliga värmeenergianvändningen och den nya kapacitetsprismodellen. Prognos 1 är baserad på en årscykel och prognos 2 baseras på intervallet november 2017 till mars 2018. Syftet med prognos 2 är att tillämpa en strategisk värmelaststyrning för att sänka värmekapacitetsbehovet vid -10˚C. Prognos 1 indikerar att en värmeenergibesparing på 26% kan uppnås. Prognosen tar hänsyn till solinstrålning och vissa delar utav den interna värmegenereringen. Utan att Diös fastigheter AB investerat i några energibesparingsåtgärder prognostiseras en besparing på 44 700SEK under ett års drift. Fastigheten har idag energiprestanda energiklass D och kommer efter besparingen att kunna uppnå energiklass C. Prognos 2 indikerar att en kapacitetsreducering kan uppnås motsvarande 46,1% samtidigt som den rörliga värmeenergianvändningen minskar. Totalt sett finns en besparingspotential på 47,8% och 216 700 SEK under perioden 2017-11-01 till 2018-03-31, dock med följd att inomhustemperaturen sjunker. / In order to continue the development towards a more sustainable city of Gävle, Gävle Energi AB will implement a new season-based capacity model by the year 2019. It creates economic incentives for energy efficiency in real estate’s within Gävle's district heating network. This report investigates how the heat energy is used for a building that risks an increased heat energy cost, due to the new pricing model. The aim of the study is to reduce the heat energy usage without investing in the building, which is made possible by regulating the thermal energy supply to the building. By programming one year of historical data of temperatures, solar radiation, power- and heat effects the heat supply is forecasted the same way as the building's control system Kabona Eco-pilot is working. The control system applies a floating indoor temperature, which contribute that the thermal inertia of the building is included in the heat load control. The study includes two forecasts that are compared to the actual heat energy use and the new capacity price model. Forecast 1 is based on an annual cycle and forecast 2 is based on the range of November 2017 to Mars 2018. The aim of forecast 2 is to apply a strategic heat load control to reduce the heat capacity needed at -10˚C. Forecast 1 indicates a potential heat energy saving of 26% even though Diös Fastigheter AB does not invest in any energy saving technology. A saving of approximately 44 700 SEK is forecasted for the annual cycle. The building has an energy class D and has the potential to achieve energy class C after the change of control system parameters. Forecast 2 indicates a potential capacity reduction corresponding to 46,1% while the variable heat energy consumption decreases. Overall, there is an approximated heat energy saving potential of 47,8%, which corresponds to 216 700 SEK, during the range of 2017-11-01 to 2018-03-31. Due to the consequence of a lower indoor temperature.
20

Estudo de casos sobre a inércia térmica de edificações na cidade de São Carlos. / Case study of buildings thermal inertia in Sao Carlos, SP.

Dornelles, Kelen Almeida 20 April 2004 (has links)
Made available in DSpace on 2016-06-02T20:09:14Z (GMT). No. of bitstreams: 1 DissKAD.pdf: 1431161 bytes, checksum: 35e43177014f0202b80650427d7d6613 (MD5) Previous issue date: 2004-04-20 / Financiadora de Estudos e Projetos / In this work, it was investigated the use of thermal inertia in buildings located in Sao Carlos city, SP, which presents semi-humid climate. This research aims to verify the hypothesis that the use of thermal inertia in buildings submitted to the specific climate of Sao Carlos allows to optimize the thermal performance of buildings and to reduce waste of energy to restore indoor thermal comfort. From data obtained by monitoring of seven different buildings, the thermal performance of each one was analyzed when they are submitted to typical simmer and winter conditions. To these seasons, adopting a reference day , it was estimated the heating and cooling requirement to restore the indoor comfort conditions. Besides the analyses for winter and summer seasons, it was estimated the indoor cooling and heating requirement along all moths of the year. Through this analyze, it was possible to verify the real influences of thermal inertia on the indoor comfort conditions. The results indicates that only the use of thermal inertia is insufficient to provide indoor thermal comfort conditions for buildings submitted to the specific climates of Sao Carlos. It is suggested to mach the use of thermal inertia with others passive strategies, in such a way to optimize the thermal performance of buildings. / Neste trabalho, investigou-se o uso da inércia térmica em edificações localizadas na cidade de São Carlos, SP, cujo clima pode se caracterizado como semi-úmido. O objetivo desta pesquisa foi verificar a hipótese de que a utilização da inércia térmica, em edificações submetidas ao clima específico da cidade, permite otimizar o desempenho térmico de edificações e reduzir a necessidade de sistemas artificiais de climatização para restabelece o conforto nos ambientes. Como base nos dados obtidos no monitoramento de ambientes de sete diferentes edificações, analisou-se o desempenho térmico de cada ambiente frente a condições típicas de inverno e verão. Para estes dois períodos, adotando-se um "dia de referência", fez-se o cálculo do desconforto por frio ou calor acumulado ao longo deste dia e se estimou a necessidade de aquecimento e refrigeração, para restabelecer o conforto térmico nos ambientes. Além das análises para inverno e verão, também se estimou a necessidade de aquecimento e refrigeração dos ambientes ao longo de todos os meses do ano. Esta análise permitiu verificar as reais influências da inércia térmica sobre as condições de conforto em edificações, as quais estão submetidas ao clima da cidade de São Carlos. As diversas formas de análise demonstram que apenas a utilização da inércia térmica não é suficiente para oferecer condições de conforto térmico nos ambientes, quando submetidos ao clima específico da cidade. Sugere-se que a utilização da inércia térmica seja combinada com outras estratégias de condicionamento passivo, de tal forma a otimizar o desempenho térmico das edificações.

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