• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 105
  • 47
  • 29
  • 18
  • 14
  • 7
  • 7
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 302
  • 123
  • 81
  • 75
  • 71
  • 66
  • 57
  • 55
  • 45
  • 42
  • 41
  • 41
  • 40
  • 35
  • 33
  • 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.
91

Energieffektivisering genom fastighetsautomation : Grundläggande teori, svensk marknadsöversikt och exempel på verklig installation

Johansson, Ola, Ulverås, Mikael January 2016 (has links)
För att uppnå Sveriges miljömål begränsad klimatpåverkan behöver åtgärder göras för att minska energianvändningen inom bostads- och servicesektorn, vilken stod för drygt en tredjedel av Sveriges totala energianvändning år 2014. Dålig styrning av värme-, ventilations- och kylsystem är ofta en bidragande orsak till onödigt hög energianvändning inom hushåll och lokalbyggnader. Med hjälp av fastighetsautomation samlas byggnadens tekniska system i ett styr- och övervakningssystem, vilket kan användas för att optimera styrningen. Dock är marknaden för fastighetsautomation dåligt kartlagd och information saknas angående styrsystemens funktioner och användningsområden. Rapporten inleds med grundläggande teori för att skapa ökad förståelse för senare delar. Därefter har en undersökning gjorts för ett antal företags styrsystem i syfte att klargöra dess funktioner, användningsområden samt vilken energibesparing styrsystemen ger upphov till. I rapporten beskrivs också tillvägagångssättet för en verklig installation i lokalbyggnaden Kv Slottet 4 och hur energianvändning samt inneklimat har påverkats efter att styrsystemet installerats. Resultatet för den svenska marknadsöversikten visar på att fastighetsautomation är etablerat inom byggnadstyperna flerbostadshus och lokalbyggnader medan småhus är en outforskad marknad. Vanliga funktioner som implementeras i styrsystem är drifttidsstyrning, prognosstyrning och effektbegränsning. Undersökningen har visat att fastighetsautomation ger upphov till energibesparingar på i snitt 10 – 40 %. Besparingen varierar dock och beror på flera faktorer som byggnadstyp, geografisk placering och tidigare styrning. Företagen använder också olika metoder för att beräkna energibesparingen varför det är problematiskt att rättvist jämföra besparingen för olika styrsystem. Energibesparingen för de olika byggnadstyperna och installationssystemen har i många fall varit svåra att få tillgång till. Generellt gäller att de företag som tillhandahåller obligatoriskt driftavtal har bättre koll på den besparing som styrsystemet ger upphov till. I examensarbetet har fyra företag kartlagts men för en mer djupgående analys över den svenska marknaden bör fler företag undersökas. Efter installationen av det automatiska styrsystemet Ecopilot® på Kv Slottet 4 erhölls en värmeenergibesparing för vald period på upp till 20,6 MWh, vilket motsvarar en procentuell besparing på 53 %. Energibesparingen varierar dock till viss del beroende på vilken beräkningsmetod som används. Byggnadens totala elbesparing uppgick till 6,5 MWh, vilket motsvarar 20 % minskning av elanvändningen för undersökt period. Den beräknade energibesparingen kan inte helt tillskrivas Ecopilot® eftersom ett annat driftfall rådde under jämförd period än det som var precis innan installationen. Via styrsystemets gränssnitt kunde emellertid en sänkt energianvändning härledas till Ecopilot®. Bland annat tack vare effektivare reglering, samkörning av installationssystem, effektivare värmeåtervinning, sänkta ventilationsflöden samt lägre inomhus- och flödestemperaturer. Intervjuer med verksamma personer i byggnaden påvisar att ingen skillnad har märkts på inomhusklimatet före och efter installationen av Ecopilot®, varken med avseende på det termiska klimatet eller på luftkvaliten. För större säkerhet gällande styrsystemets inverkan på inomhusklimatet och energianvändningen bör en längre tidsperiod utvärderas. / Sweden has a number of environmental objectives, of which one is reduced climate impact. To achieve this goal measures have to be taken in order to reduce building energy use in residential and services sectors, sectors that accounted for over one third of Sweden’s total energy use in 2014. Poor regulation of heating, ventilation, and air conditioning (HVAC) is a common reason for often unnecessary high energy use in residential buildings and non-residential premises. Building automation integrates the buildings technical systems, such as HVAC, into one centralized system for monitoring and controlling, which then can be used to optimize the regulation for these systems. The market is however poorly mapped and information is missing regarding functions and area of use for these control systems. This report begins with a description of basic theory that is relevant for understanding parts later on. An analysis has then been made for a number of different building automation systems to clarify their functions, area of use, and potentials in energy savings. The report also describes the procedure for a real installation on Kv Slottet 4 and how the energy use and indoor climate has been affected after the building automation system has been installed. Results regarding the Swedish market overview shows that building automation is established in apartment buildings and non-residential premises while building automation is still unused in smaller houses. Some of the most common functions that are implemented in control systems are time clock operation, forecast control and power limitation. The analysis has shown that building automation can lead to energy savings between 10 to 40 %. The size of the saved energy depends on a number of factors like type of building, geographical location and former regulation of HVAC. The building automation companies are using different methods to calculate the energy saving why it is a problem to fairly compare different control systems. The information on energy savings for different type of buildings and technical systems are in many cases hard to get hold of. Generally speaking, the companies that provide mandatory agreements for operating the control system have more detailed information regarding energy savings. Four different companies were covered in this report. More companies should be mapped in order to make a more profound analysis. After the installation of Ecopilot® on Kv Slottet 4, a heat reduction of up to 20.6 MWh for the chosen period of time was achieved. That corresponds to a relative energy saving of 53 %. The energy saving varies depending on what method is used for calculation. The buildings total energy savings for electricity was 6.5 MWh, which corresponds to a 20 % reduction. The calculated energy saving is not all due to the building automation system but there has been some reduction. Ecopilot® has lowered the energy use by more efficient regulation, co-operating heating and cooling, more efficient heat recovery, lowered ventilation flows, and lowered temperatures. No change in indoor climate has been noticed by the people that were interviewed. The control system should be evaluated for a longer period of time to ensure how much it affects the indoor climate and the energy use in the building.
92

A technical and economic feasibility study for the integration of GSHP technology in the Christchurch rebuild

Bustard, Samuel Kent January 2014 (has links)
Mr Wayne Tobeck, Director of Southrim Group (SRG), sponsored this 2013 MEM Project titled; A Technical and Economic Feasibility Study for the Integration of GSHP Technology in the Christchurch Rebuild. Following the recent Christchurch earthquakes, a significant amount of land has become too unstable to support traditional building foundations. This creates an opportunity to implement new and unique foundation designs previously unconsidered due to high costs compared to traditional methods. One such design proposes that an Injection Micro-Piling technique could be used. This can also be coupled with HVAC technology to create a Ground Source Heat Pump (GSHP) arrangement in both new buildings and as retrofits for building requiring foundation repair. The purpose of this study was to complete a feasibility study on the merits of SRG pursuing this proposed product. A significant market for such a product was found to exist, while the product was also found to be technically and legally feasible. However, the proposed product was found to not be economically feasible with respect to Air Source Heat Pumps due to the significantly higher capital and installation costs required. Further analysis suggests GSHPs may become more economically attractive in operating temperatures lower than -9oC, though the existence of markets with this climate in NZ has not been studied. It is therefore suggested that SRG do not proceed with plans to develop a GSHP coupled foundation solution for the Christchurch rebuild.
93

Ground-coupled heat pump systems: a pumping analysis

Mays, Cristin Jean January 1900 (has links)
Master of Science / Department of Architectural Engineering / Fred Hasler / Ground-coupled heat pump (GCHP) systems use the ground as a heat source or sink that absorbs heat from or rejects heat to the soil, respectively; this is referred to as the geothermal heat exchanger. Apart from the geothermal heat exchanger, there are two other main system components that make up a GCHP system: heat pumps and circulation pumps. This report studies four GCHP pumping systems and makes comparisons between the four using life-cycle cost analyses for six building models. The goal for this analysis was to discover commonalities between the models in order to provide designers insight into which pumping system is the most cost effective. The analysis was performed by first creating energy models to obtain system and zone load information, as well as system part-load data and geothermal heat exchanger performance. From the zone load information, heat pump selections were then performed to indicate the worst case piping path that is required for pump head calculations. Piping layouts were created to establish pipe lengths for the pump head calculations as well. Other piping components such as valves and fittings and the air separator pressure drops were also calculated. Once the pump head calculations were complete for each system, pump schedules were created. From there initial unit and installation costs were determined for each pump, as well as their replacement costs. The part-load data from the energy models were then used to obtain annual pump energy consumption and pump utility cost. Finally, assumptions were made to establish regular and preventative maintenance requirements for each pumping system. Initial and replacement unit costs, annual utility cost and regular and preventative maintenance costs were the components used in the life-cycle cost analysis. Each of these components was converted to 30-year projected costs and added to create a total life-cycle cost for each pumping system. Comparisons were then made and the results showed that a primary pumping system with VFD control and 100% redundancy was the most cost effective system. However, there are other considerations such as controllability, flexibility and availability that might persuade designers to choose one of the other alternate solutions.
94

Determinação de parâmetros de operação de sistema de distribuição de ar frio pelo piso em ambientes de escritórios. / Determination of operation in office rooms with underfloor air distribution system.

Abe, Viviane Caroline 31 May 2007 (has links)
ABE, V.C. Determinação de parâmetros de operação de sistema de distribuição de ar frio pelo piso em ambientes de escritórios. 2007. 132 p. Dissertação (Mestrado) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Atualmente, um dos principais requisitos para que um ambiente de escritório atenda plenamente às necessidades de uso e ocupação é a flexibilidade, mas com conforto. O sistema de distribuição de ar frio pelo piso (Underfloor Air Distribution System - UFAD) está sendo utilizado nos edifícios de escritórios para garantir a flexibilização integrada do sistema com o mobiliário. Trata-se de um sistema que fornece ar frio proveniente de um plenum, através de difusores localizados nos painéis do piso elevado. Os difusores de ar podem ser ajustados, ou reposicionados pelos próprios usuários dos ambientes, possibilitando o controle das condições térmicas no entorno próximo, de acordo com suas preferências individuais. Embora o sistema de distribuição de ar pelo piso apresente diversas vantagens com relação ao sistema de distribuição de ar convencional, ainda há falta de informações objetivas e diretrizes de projeto padronizadas, havendo a necessidade de realização de mais pesquisas na área. A introdução da Dinâmica dos Fluidos Computacional (Computational Fluid Dynamics - CFD) apresentou uma alternativa para as pesquisas experimentais relacionadas ao estudo do escoamento do ar. Assim, para o desenvolvimento do presente estudo foram utilizados recursos de dinâmica dos fluidos computacional, com o uso do código FLUENT. O objetivo do presente trabalho é apresentar uma estratégia para a determinação dos parâmetros de operação de sistemas de distribuição de ar pelo piso aplicados a ambientes de escritórios. A estratégia baseiase no estabelecimento de inter-relações entre os principais parâmetros que definem o escoamento do ar em ambientes com o sistema de distribuição de ar pelo piso: a vazão de ar insuflado, a temperatura do ar insuflado e a diferença de pressão entre o plenum pressurizado e o interior do ambiente. O emprego da estratégia possibilita que o projetista identifique as diversas combinações entre os parâmetros de operação que resultem numa mesma condição desejada, permitindo assim a escolha da opção mais satisfatória. / ABE, V.C. Determination of operation parameters of rooms with underfloor air distribution system. 2007. 132 p. Dissertation (Master Course) - Departamento de Engenharia de Construção Civil da Escola Politécnica da Universidade de São Paulo, São Paulo, 2007. Nowadays, one of the main requirements of an office room to fully attend the use and occupation needs is the flexibility, but with comfort. The underfloor air distribution system is being used in the office buildings to guarantee the integrated flexibility of the system with the furniture layout. The system supplies cooled air to the room from a pressurized plenum, passing through air diffusers located in the raised floor panels. The air diffusers can be adjusted or relocated by the room users themselves, making possible the control of the thermal conditions in their surroundings, according to their individual preferences. Though the underfloor air distribution system presents a lot of advantages with regard to conventional overhead distribution systems, there is still a lack of objective information and standardized guidelines, and the necessity of accomplishment of more researches about the subject. The introduction of Computational Fluid Dynamics presented an alternative for the experimental tests related to the study of airflow in rooms. Thus, for the development of the present study a CFD tool was used, the code FLUENT. The purpose of the present work is to develop a strategy for the determination of the operation parameters of an underfloor air distribution system applied to office rooms. The strategy is based on the establishment of interrelations between the main parameters that define the airflow in rooms with the underfloor air distribution system: the input volume flux, the input air temperature and the pressure difference between underfloor plenum and the room. The use of this strategy enables the designer to identify several combinations of the operation parameters that result in one desired condition, allowing the choice of the most satisfactory option.
95

Investigation of the energy efficient sustainable manufacturing approach and its implementation perspectives

Katchasuwanmanee, Kanet January 2016 (has links)
In the last two decades, energy is becoming one of the main issues in the manufacturing industry as it contributes substantially to production cost, CO2 emissions, and other destructive environmental impact. Due to rising energy costs, environmental concerns and stringent regulations, manufacturing is increasingly driven towards sustainable manufacturing which needs to address the associated environmental, social and economic aspects simultaneously. One common approach is to achieve sustainability and to implement energy-resource efficient production management systems that enable optimisation of energy consumption and resource utilisation in the production system. However, by reducing energy consumption, the product quality and production cost may be compromised. To remain competitive in the dynamic environment, the energy-efficient management system should not only concern energy consumption but also maintain product quality and production efficiency. This thesis presents a development of the Energy-smart Production Management (e-ProMan) system which provides a systematic, virtual simulation that integrates manufacturing data relating to thermal effect and correlation analysis between energy flow, work flow and data flow for the heating, ventilation and air conditioning (HVAC) system and production process. First, the e-ProMan system comprises of the multidimensional analysis between energy flow, work flow and data flow. The results showed that the product quality is significantly affected by ambient temperature in CNC precision machining. Product quality appears to be improved at lower temperatures. This research highlights the significance of ambient temperature in sustainable precision machining. Second, the simulation experiment was modelled at the production process due to it being the main source of energy consumption in manufacturing. An up-hill workload scenario was found to be the most energy and cost-efficient production processes. In other words, energy consumption, CO2 emission and total manufacturing cost could be reduced when workload capacity and operating machine increase incrementally. Moreover, the e-ProMan system was modelled and simulated using the weather forecast and real-time ambient temperature to reduce energy consumption of the HVAC system. The e-ProMan system results in less energy consumption compared to the fuzzy control system. To conclude, the e-ProMan demonstrates energy efficiency at all relevant levels in the manufacturing: machine, process and plant. For the future research, the e-ProMan system needs to be applied and validated in actual manufacturing environments.
96

NUMERICAL AND EXPERIMENTAL TECHNIQUES FOR ASSESSING THE ACOUSTIC PERFORMANCE OF DUCT SYSTEMS ABOVE THE PLANE WAVE CUTOFF FREQUENCY

Ruan, Kangping 01 January 2018 (has links)
This research deals with determining the acoustic attenuation of heating, ventilation, and air conditioning (HVAC) ductwork. A finite element approach was developed for calculating insertion loss and breakout transmission loss. Procedures for simulating the source and receiving rooms were developed and the effect of structureborne flanking was included. Simulation results have been compared with measurements from the literature and the agreement is very good. With a good model in place, the work was extended in three ways. 1) Since measurements on full-scale equipment are difficult, scale modeling rules were developed and validated. 2) Two different numerical approaches were developed for evaluating the transmission loss of silencers taking into account the effect of higher order modes. 3) A power transfer matrix approach was developed to assess the acoustic performance of several duct components connected in series.
97

The effect of energy recovery on indoor climate, air quality and energy consumption using computer simulations

Fauchoux, Melanie 23 June 2006
The main objectives of this thesis are to determine if the addition of an energy wheel in an HVAC system can improve the indoor air relative humidity (RH), and perceived air quality (PAQ), as well as reduce energy consumption. An energy wheel is an air-to-air energy exchanger that transfers heat and moisture between the outdoor air entering and the exhaust air leaving a building. This thesis uses the TRNSYS computer package to model two buildings (an office and a school) in four different cities (Saskatoon, Saskatchewan; Vancouver, British Columbia; Tampa, Florida and Phoenix, Arizona).<p>The results with and without an energy wheel are compared to see if the energy wheel has a significant impact on the RH and PAQ in the buildings. The energy wheel reduces peak RH levels in Tampa, (up to 15% RH), which is a humid climate, but has a smaller effect on the indoor RH in Saskatoon (up to 4% RH) and Phoenix (up to 11% RH), which are dry climates. The energy wheel also reduces the number of people that are dissatisfied with the PAQ within the space by up to 17% in Tampa. <p>The addition of the energy wheel to the HVAC system creates a reduction in the total energy consumed by the HVAC system in Saskatoon, Phoenix and Tampa (2% in each city). There is a significant reduction in the size of the heating equipment in Saskatoon (26%) and in the size of the cooling equipment in Phoenix (18%) and Tampa (17%). A cost analysis shows that the HVAC system including an energy wheel has the least life-cycle costs in these three cities, with savings of up to 6%. In Vancouver, the energy wheel has a negligible impact on the indoor RH, PAQ and energy consumption.
98

Design and performance testing of counter-cross-flow run-around membrane energy exchanger system

Mahmud, Khizir 29 September 2009
In this study, a novel counter-cross-flow run-around membrane energy exchanger (RAMEE) system was designed and tested in the laboratory. The RAMEE system consists of two (2) counter-cross-flow Liquid-to-Air Membrane Energy Exchangers (LAMEEs) to be located in the supply and exhaust air streams in the building Heating Ventilation and Air-Conditioning (HVAC) system. Inside each exchanger, a micro-porous membrane separates the air and liquid streams and allows transfer of the sensible and latent energy from the air stream to the liquid stream or vice-versa. The system exchanges sensible and latent energy between supply and exhaust air streams using a desiccant solution loop. The supply and exhaust air streams in the RAMEE can be located far apart from each other or adjacent to each other. The flexibility of non-adjacent ducting makes the RAMEE system a better alternative compared to available energy recovery systems for the retrofit of HVAC systems.<p> Two counter-cross-flow exchangers for the RAMEE system were designed based on an industry recommended standard which is to obtain a target overall system effectiveness of 65% for the RAMEE system at a face velocity of 2 m/s. The exchanger design was based on heat exchanger theory and counter-cross-flow design approach. An exchanger membrane surface aspect ratio (ratio of exchanger membrane surface height to exchanger length) of 1/9 and the desiccant solution entrance ratio (ratio of desiccant solution entrance length to exchanger length) of 1/24 were employed. Based on different heat transfer case studies, the energy transfer size of each exchanger was determined as 1800 mm x 200 mm x 86 mm. ProporeTM was used as the membrane material and Magnesium-Chloride solution was employed as the desiccant solution.<p> The RAMEE performance (sensible, latent and total effectiveness) was evaluated by testing the system in a run-around membrane energy exchanger test apparatus by varying the air stream and liquid solution-flow rates at standard summer and winter operating conditions. From the test data, the RAMEE effectiveness values were found to be sensitive to the air and solution flow rates. Maximum total effectiveness of 45% (summer condition) and 50% (winter condition) were measured at a face velocity ¡Ö 2 m/s. A comparison between the experimental and numerical results from the literature showed an average absolute discrepancy of 3% to 8% for the overall total system effectiveness. At a low number of heat transfer units, i.e. NTU = 4, the numerical and experimental results show agreement within 3% and at NTU = 12 the experimental data were 8% lower than the simulations. The counter-cross-flow RAMEE total system effectiveness were found to be 10% to 20% higher than those reported for a cross-flow RAMEE system by another researcher.<p> It is thought that discrepancies between experimental and predicted results (design and numerical effectiveness) may be due to the mal-distributed desiccant solution-flow, desiccant solution leakage, lower than expected water vapor permeability of the membrane, uncertainties in membrane properties (thickness and water vapor permeability) and heat loss/gain effects. Future research is needed to determine the exact cause of the discrepancies.
99

A Comparison of Fault Detection Methods For a Transcritical Refrigeration System

Janecke, Alex Karl 2011 August 1900 (has links)
When released into the atmosphere, traditional refrigerants contribute to climate change several orders of magnitude more than a corresponding amount of carbon dioxide. For that reason, an increasing amount of interest has been paid to transcritical vapor compression systems in recent years, which use carbon dioxide as a refrigerant. Vapor compression systems also impact the environment through their consumption of energy. This can be greatly increased by faulty operation. Automated techniques for detecting and diagnosing faults have been widely tested for subcritical systems, but have not been applied to transcritical systems. These methods can involve either dynamic analysis of the vapor compression cycle or a variety of algorithms based on steady state behavior. In this thesis, the viability of dynamic fault detection is tested in relation to that of static fault detection for a transcritical refrigeration system. Step tests are used to determine that transient behavior does not give additional useful information. The same tests are performed on a subcritical air-conditioner showing little value in dynamic fault detection. A static component based method of fault detection which has been applied to subcritical systems is also tested for all pairings of four faults: over/undercharge, evaporator fouling, gas cooler fouling, and compressor valve leakage. This technique allows for low cost measurement and independent detection of individual faults even when multiple faults are present. Results of this method are promising and allow distinction between faulty and fault-free behavior.
100

Statushantering i Virtual Map med ledningssamordning i BIM / Status Management in Virtual Map with Pipe Coordination in BIM

Genchel, Jonas January 2010 (has links)
For many years, the construction industry in Sweden has not developed much of an integral approach for design across disciplines. The sector’s impact on society, economics and environment is huge. To make the interactions within the construction industry more efficient, a relatively new concept called BIM (Building Information Modeling) has been introduced. The idea with BIM is that the different actors of the construction industry will work through intelligent CAD software, with common file formats and more cooperation between different actors during the various steps of the building and construction process. The technical consultancy company WSP Sweden is working actively to implement BIM within the frame of its activities. One step towards BIM is the use of their visualization software Novapoint Virtual Map in a better way. They lack a good system to show which pipes belongs to different documents, i.e. some kind of status management. Another step towards BIM is to be able to change and revise Water and Sewage 3D-models with HVAC 3D-models, and to be able to detect possible errors in the connection nodes early in the designing stage. In this thesis work, a CAD-model has been created in Novapoint VA, the CAD software used to design pipe and sewage systems at WSP. The designed model is divided into many stages which creates many parallel documents at the same time. The model is visualized in Novapoint Virtual Map where functions for status management are created. With the help of grouping functions in the software it is possible to show pipes that belong to different documents at the same time. The more documents there are in the same model the longer it takes to create the model, which is something that could be improved in later editions of the software. In this paper, seven tests were carried on to examine how water and sewage pipes CAD-models created in Novapoint VA can be jointly revised with HVAC CAD-models created in MagiCAD. The result of the test shows that four of these tests can be used to revise the models. To use one of these methods, according to the BIM model, for changes and revisions of models can help avoid mistakes in connection points already at design stage.

Page generated in 0.0284 seconds