• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 17
  • 7
  • 5
  • 2
  • 1
  • Tagged with
  • 33
  • 33
  • 16
  • 15
  • 13
  • 11
  • 10
  • 8
  • 8
  • 8
  • 6
  • 6
  • 5
  • 5
  • 5
  • 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

Optimering av last och produktion i Gävles fjärrvärmenät : Reducering av effekttoppar via värmelagring i byggnader

Elofsson, Fredrik January 2019 (has links)
District heating is today the most common way of providing a building with heat and hot water in Sweden. It is an environmentally friendly product mostly used with renewable fuel. However, at power peaks most companies use production units that are more expensive and worse for the environment and should therefore be avoided as much as possible. This can be done with a method called load management. When a power peak occurs, the heat supply to buildings connected to the district heating system can be temporarily reduced. The heat energy can later be returned when the heat demand is lower. Thanks to the heat inertia of the buildings, the indoor temperature will not fall within the time frame for the load management. Historical data has been analysed to identify when and why power peaks occur in the district heating network. Power peaks throughout the district heating network have proved difficult to identify. However, for individual consumers clear patterns of power peaks have emerged. These power peaks mainly occur because of large use of hot water but also because of the shifting outdoor temperature. In order to see how the production cost would differ from the actual outcome load management was applied for Gävle's district heating 2018. The load management was calculated manually by identifying the most expensive production unit on an hourly basis. If a cheaper production unit had the potential to deliver higher power the next hour, the production was moved to the cheaper production unit. The process was repeated for each hour during 2018. After carrying out load management for Gävle's district heating network, 1 457 MWh had been shifted to a cheaper production unit. This resulted in a financial saving of 1,0 % of the total production cost. The environmental savings showed a reduction from 6.1 to 5.9 g CO2eq /kWh a total of 197 tonne CO2eq. In the exact same way, a load management was performed for a scenario where Gävle and Sandviken's district heating network were connected. The gain for a load management with Sandviken will be considerably larger, a reduced production cost of 3.6 % is possible. The environmental savings showed a reduction from 8.4 to 7.8 CO2eq /kWh a total of 575 tonne CO2eq. For future efficient load management, buildings should be divided into different classes depending on the building's time constant. User patterns for the entire district heating network have proved difficult to detect. Artificial intelligence can be an option for short-term forecasting of the power output / Fjärrvärme är idag det vanligaste sättet att förse en bostad med värme och tappvarmvatten i Sverige. Fjärrvärmen är ofta en miljövänlig produkt som kan produceras av till exempel biobränsle- och avfallseldade kraftvärmeverk eller spillvärme från industrier. Vid tillfälligt högt effektbehov, effekttoppar, använder sig merparten av bolagen av dyrare produktionsenheter med större miljöpåverkan. Dyrare produktionsenheter bör undvikas i största möjliga mån och i detta syfte används metoden laststyrning. Vid en effekttopp kan värmetillförseln till byggnader sänkas temporärt för att återföras några timmar senare när effektbehovet är lägre. Tack vare värmetrögheten i byggnaderna bör inomhustemperaturen inte sjunka inom tidsramen för laststyrning. Statistik från Gävles fjärrvärmanvändning på timbasis under 2018 har analyserats för att identifiera när och varför effekttoppar sker. Effekttoppar i hela fjärrvärmenätet har visat sig svåra att identifiera. På lokal nivå har däremot tydliga mönster för effekttoppar framkommit. Dessa effekttoppar beror till största del av tappvarmvattenanvändning men även förändringar i utomhustemperaturen. För att se hur produktion och last kunde skiljt sig från det verkliga utfallet tillämpades laststyrning för Gävles fjärrvärmeproduktion 2018. Laststyrningen beräknades manuellt genom att den dyraste produktionsenheten identifierades på timbasis. Om en billigare produktionsenhet hade potential att leverera högre effekt nästkommande timmar försköts produktionen. Därefter upprepades processen för varje timme under 2018. Efter utförd laststyrning för Gävles fjärrvärmenät hade ca 1 457 MWh förskjutits till en billigare produktionsenhet. Det gav en ekonomisk besparing på 1,0 % av Gävles totala produktionskostnad. Den miljömässiga besparingen visade på en sänkning från 6,1 till 5,9 [g CO2ekv /kWh] sammanlagt 197 ton CO2ekv. På samma sätt utfördes en laststyrning för ett scenario där Gävle och Sandvikens fjärrvärmenät sammankopplats. Vinsten för en laststyrning med Sandviken blev betydligt större med en minskad produktionskostnaden på 3,6 %. Den miljömässiga påverkan sjönk från 8,4 till 7,8 g CO2ekv /kWh sammanlagt 575 ton CO2ekv. För en framtida effektiv laststyrning bör byggnader delas in i olika klasser beroende på byggnadens tidskonstant. Användarmönster för hela fjärrvärmenätet har visat sig svårt att identifiera. Artificiell intelligens kan vara ett alternativ i framtiden för att prognostisera effektuttaget
12

Tela de sombreamento e pintura em telhados de modelos reduzidos de galpões avícolas /

Gomes Filho, João Soares. January 2010 (has links)
Resumo: Quatro experimentos foram conduzidos para avaliar o efeito do sombreamento artificial e da pintura dos telhados na melhoria do conforto térmico de modelos reduzidos simulando galpões avícolas. Em todos os experimentos foram utilizadas coberturas com telha de fibrocimento, novas, sem cimento amianto, com 4,0mm de espessura. O Experimento 1 foi realizado na Universidade Estadual do Maranhão (UEMA), câmpus de São Luís, onde foram testados cinco tipos de coberturas: 1- sem tela, sem pintura (STSP - controle); 2- com tela a 0,05m de altura da telha, sem pintura (CT5SP); 3- com tela a 0,05m de altura da telha, com pintura (CT5CP); 4- com tela a 0,08m de altura da telha, sem pintura (CT8SP) e 5- com tela a 0,08m de altura da telha, com pintura (CT8CP). Foram determinados o Índice de Temperatura de Globo Negro e Umidade (ITGU), a Carga Térmica de Radiação (CTR) e a Entalpia Específica (H). As colheitas das variáveis meteorológicas (temperaturas de globo negro, de bulbo seco, de bulbo úmido e velocidade do vento) foram realizadas durante 12 dias experimentais (04 a 15 de nov. de 2009) às 10:00, 12:00, 14:00 e 16:00 horas. O tipo de cobertura CT5SP foi o que apresentou os melhores valores para ITGUcorr (79,81) e H (78,84 KJ.Kg-1 de ar seco). O melhor resultado para CTRcorr foi apresentado pelo tratamento CT5CP (480,12 W.m-2). O Experimento 2 foi realizado na Universidade Estadual Paulista (UNESP), câmpus de Jaboticabal, onde foram testados os mesmos tipos de coberturas do Experimento 1. As colheitas e registro das variáveis meteorológicas foram realizadas por 40 dias (13 de fev. a 24 de mar. de 2010), nos mesmos horários do Experimento 1. O tipo cobertura que proporcionou menor resultado para o ITGU (83,86) e H (86,41 KJ.Kg-1 de ar seco) foi o CT8CP. A menor CTR (549,52 W.m-2) foi verificada na cobertura CT5CP. O Experimento 3 objetivou verificar o efeito de dois tipos de telas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Four experiments were conducted to assess the effect of shading and painting of roofs improving thermal comfort in reduced models of poultry houses. In all the experiments were used with roofing cement tile, new, no asbestos cement, with 4.0 mm thick. The first experiment was conducted at the Universidade Estadual do Maranhão (UEMA), campus of São Luís, where were tested five types of coverage: 1 - no shading, no paint (STSP - control), 2 - with shading 0.05 m in height tile, unpainted (CT5SP) 3 - with shading 0.05 m in height tile with painting (CT5CP) 4 - with shading 0.08 m in height tile, unpainted (CT8SP) and 5 - with shading 0.08 m height of the tile with painting (CT8CP). Were evaluated the index of black globe temperature and humidity (BGTHI), the Heat Load (HL) and the specific enthalpy (H). The readings of meteorological variables (black globe temperature, dry bulb, wet bulb temperatures and wind speed) were measured during 12 experimental days (from nov. 4th to 15th, 2009) at 10:00, 12:00, 14: 00 and 16:00 hours. The type of coverage CT5SP had the lowest values for BGTHI (79,81) and H (78,84 KJ.Kg-1 dry air). The best result for CTRcorr (480,12 W.m-2) was presented by treatment CT5CP. The second experiment was conducted at Universidade Estadual Paulista (UNESP), campus of Jaboticabal, where were tested the same types of coverages of Experiment 1. The collection and recording of meteorological variables were performed for 40 days (from feb. 13th to 24th, 2010), at the same times of Experiment 1. The type coverage that provided smaller results for the BGTHI (83,86) and H (86,41 KJ.Kg-1 dry air) was CT8CP. The lower HL (549,52 W.m-2) was verified with the coverage CT5CP. The third experiment aimed at assessing the effect of two types of shading screens (50 and 80%) on the thermal comfort... (Complete abstract click electronic access below) / Orientador: Renato Luís Furlan / Coorientador: Adhemar Pitelli Milani / Banca: Euclides Braga Malheiros / Banca: José Eduardo Pitelli Turco / Banca: Iran José Oliveira da Silva / Banca: Francisca Neide Costa / Doutor
13

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.
14

Výpočet tepelné zátěže vlakové klimatizační jednotky / Calculation of the heat load of the train air conditioning unit

Kasal, Milan January 2018 (has links)
The subject of this diploma thesis is to apply the knowledge of thermodynamics when designing parameters of the train air conditioning unit. In the first part, the issue of air conditioning technology, basic types of cooling circuits and description of individual components are outlined. Furthermore, there is an overview of groups of refrigerants and their labelling. In the second part, a calculation of the heat load of the train unit for the limit design conditions of summer and winter operation, including the application of humid air theory are to be found. There is a basic procedure for designing the main components of compressor cooling, which is almost exclusively used in train applications, outlined. The last part contains the procedure for calculating the gains/losses in the distribution channels of the real air conditioning unit M7 and the evaluation of the results. In the appendix, there is an SW in MS Excel program, which can be indicatively used to calculate the total gains/losses of the distribution channels on any air-conditioning unit before the air enters into the train unit.
15

Filtrace vzduchu / Air filtration

Krajčová, Kateřina January 2019 (has links)
The diploma thesis describes the design of air conditioning equipment of materni-ty hospital and experimental measurement nanofilters and their subsequent comparison with conventional air filters. The work consists of three parts. The first part describes the types of filters. Nanofilters and nanofiber materials are de-scribed in detail here. In the second part is the topic of air filtration applied to the maternity hospital. Two variants of air conditioning and cooling are designed for the 3rd floor of this building. The third experimental part deals with antibacterial effects of thr silver fiber nanofilter and its comparison with commonly used filters. It also deals with the pressure drop on the filters at different air speeds.
16

Zátěžové testy non-IT částí datových center / Load tests of non-IT parts of data centers

Víteček, Aleš January 2019 (has links)
The thesis "Load testing of non-IT parts data centers" deals with the theoretical analysis of data centers with a focus on non-IT part and theoretical preparation for measuring stress tests focused mainly on cooling. The theory is followed by a practical part of the PEC measurement by CATEGORY a.s .. This sample measurement carried out at the company premises clearly outlines the importance of performing similar tests. The measurement is thoroughly evaluated and suggestions are made to improve the operation. The next part of the practical part contains simulation of sample measurement. This simulation serves as a convenient addition and comparison. Also this simulation, the importance of similar stress tests can be justified.
17

Návrh vzduchotechniky v multifunkční sportovní hale / Air conditioning design in multifunctional sports hall

Navrátil, Radek Unknown Date (has links)
The diploma thesis deals with the design of air-conditioning equipment in the building of a multifunctional hall in Brno and also includes an experimental analysis of air flow. It consists of 3 parts. In the first part a theory of air distribution is elaborated. The second part deals with the analysis of air flow for different types of air diffusers and for one diffuser further looks for a simplified model. The last part of this work is focused on the design of air conditioning equipment in the assigned building, the multifunctional sports hall.
18

Klimatizace učeben a kanceláří / Air-conditioning of lecture rooms and offices

Bečvář, Jaroslav January 2008 (has links)
The diploma thesis is consisting of two parts. Forepart is a theoretic survey. It construes basic office of the air conditioning and deal with used air conditioner arrangements. More deeply it deals with air conditioner systems with refrigerant and the air conditioning for electronic equipments. Project of split system for air conditioning lecture rooms and schoolrooms, and units for air conditioning rooms with cluster and server is processed in the second part. Project is derives from calculation thermal stress of air conditioned space. There is calculated price of air conditioner system and made comparison offers of several accessible suppliers. Elaboration drawing documentation of project is part of the diploma thesis.
19

Klimatizace administrativní budovy / Air - conditioning of office building

Birhanzl, Petr January 2011 (has links)
The thesis describes the various ventilation and air conditioning systems used to maintain suitable, temperature-humidity parameters of air in office buildings. The thesis deals with their advantages and disadvantages and assessing the suitability of using several systems for the application. The main task is to choose the most suitable system and it's calculation. For the actual system design is needed to detect a heat loss and gains the specified object and calculate the minimum amount of ventilation air. There will also be given psychrometric calculation of a device and drawing documentation, including draft of an engine room.
20

Svázání fyziologického modelu s modelem tepelného komfortu / Coupling of the Models of Human Physiology and Thermal Comfort

Pokorný, Jan January 2012 (has links)
The thesis deals with car cabin environment and thermal comfort inside. A car cabin heat load model was developed in Dymola/Modelica to investigate influence of ambient environmental parameters. The model was validated on the data set of eight test cases measured in a climatic chamber and in a real traffic. The main objective of the thesis was to develop a human thermal comfort model suitable for non-homogenous environments and for a car cabin environment especially. The Coupled model of human physiology and thermal comfort was developed in Dymola/Modelica. The model allows predicting an overall human thermal comfort from local boundary conditions representing ambient and personal factors. The model was validated by 16 test cases taken from experiments in literature. Moreover three test cases were created in Theseus-FE to consider an asymmetrical heat load from Sun rays inside a car cabin. Prediction of the Coupled model was compared with Fiala model and experimental data. The Coupled model predicted mean skin temperature for moderate activities in neutral and warm environment well. In cold environment a predicted core temperature was very affected by ambient temperature and during high activity exercises, the predicted mean skin temperature was too high.

Page generated in 0.2613 seconds