• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 171
  • 146
  • 37
  • 25
  • 12
  • 9
  • 6
  • 5
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 470
  • 470
  • 207
  • 146
  • 145
  • 140
  • 121
  • 89
  • 84
  • 83
  • 82
  • 74
  • 71
  • 59
  • 57
  • 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.
41

Energy audit and saving analysis of a building : Study of heat pump installation and district heating connection

Urtasun, Cristina January 2008 (has links)
<p>The object of analysis in the present document is a residential house in Sätra. This building has a hydronic space heating system with radiators spread around the house and a heating recovery system ventilation which also use water for reheating. Water for space heating, ventilation and hot tap water is nowadays heated in an electric boiler.The aim of this project is to make a diagnosis of the current situation, evaluate different alternatives for supplying hot water to the house, and to study costs and possible savings by comparing the actual facilities with the proposals done.</p>
42

Heat Pump System using Waste Energy for a District Heating Application

Vivas, David January 2008 (has links)
<p>Nowadays, reducing energy usage as well as reducing environmental impacts due to energy efficiency measurements is very common in the industrial sector. The objective of these measurements is to achieve better sustainable energy systems.</p><p>Sandvik Materials Technology (SMT) AB, one of the business areas of the enterprise Sandvik AB, is not an exception in that field.</p><p>The aim of this thesis project is to analyze how to use waste energy from the cooling of a steel plant for an internal district heating (DH) system within the industrial area of SMT AB located in Sandviken, Sweden. In order to reduce the energy use, the economic cost and the environmental impacts within the industrial area.</p><p>In order to achieve the aim has been studied the heat pump devices as the system to transfer the waste heat from the cooling of the steel plant to the DH system. Therefore, after the introduction to the project (part 1: Introduction) and the explanation of the aim</p><p>(part 2: Aim, methodology and delimitations), the basics of the heat pumps are studied and explained (part 3: Heat pumps theoretical study). After that, the knowledge acquired in part 3 is applied to define and calculate the heat pump system which fulfill the required</p><p>objectives achieving the greatest energy, economical and environmental impacts reductions (part 4: Heat pump practical study).</p><p>The achieved results show that there is a great opportunity to reduce the energy use within the industrial area (until 45300 MWh per year), the economical cost (until 2 millions euros per year) and the 2 CO emissions (until 2.3 millions of 2 CO kg per year1).</p><p>Therefore, the conclusion is that it must be taken into account to build the heat pump system and also that the effort of finding possible energy efficiency measurements within the industrial sector must be one priority for all the industrial companies, not only because the possible potential economical reductions, but also because of the potential environmental impacts reductions.</p>
43

Simulation and Validation of a Single Tank Heat Pump Assisted Solar Domestic Water Heating System

Wagar, William Robert January 2013 (has links)
This thesis is a study of an indirect heat pump assisted solar domestic hot water (I-HPASDHW) system, where the investigated configuration is called the Dual Side I-HPASDHW system. The study outlines the development of an Experimental Test Unit (ETU), and focuses on the experimental validation of TRNSYS models. Shortcomings of the system design realized throughout the validation process, as well as weaknesses in the control schemes used to operate the system are also provided. A description of the Dual Side I-HPASDHW system is provided along with the design intent of the system. The corresponding ETU is presented in detail to provide a comprehensive understanding of the ETU’s simulation capabilities. Components of the ETU, such as the heat pump, heat exchanger, and domestic hot water (DHW) tank are characterized in order to provide input data for built-in TRNSYS models, and to develop custom TRNSYS models for the heat pump and heat exchanger. Heat exchanger performance is modelled with a linear correlation, while the heat pump performance is mapped by applying experimental data to three-dimensional surface fitting software. For the purpose of validation, the ETU is used to simulate the performance of the Dual Side I-HPASDHW system under a realistic control scheme. Four full day tests are conducted using data from a fall, winter, and summer day. The full day summer test is repeated with and without electrical backup heating. The TRNSYS model of the Dual Side system is tuned in order to provide the closest match possible between the computer simulation and the measured performance of the ETU. Experimental tests were compared with TRNSYS simulations to reveal some disparity in the results. The majority of simulation error was attributed to inaccuracy in modeling DHW tank temperatures and water circulation patterns. The disparity created by the DHW tank model only resulted in substantial performance deviation when inaccurate DHW temperatures were used directly for vital control decisions. Conclusions were drawn suggesting that the TRNSYS model of the ETU was valid for a majority of operating conditions, often matching experimental tests well within experimental uncertainty. Caution was recommended towards the use of the developed TRNSYS model, where techniques were recommended for tracking and minimizing substantial simulation errors. Several key performance issues affecting the Dual Side I-HPASDHW system were targeted with recommendations for design and control alterations, along with future improvement and optimization studies.
44

追設凝縮器を用いた空調機の運転

後藤, 誠, GOTO, Makoto, 谷藤, 浩二, TANIFUJI, Koji, 藤田, 真弘, FUJITA, Masahiro, 山内, 智裕, YAMAUCHI, Tomohiro, 永田, 謙二, NAGATA, Kenji, 上野, 勲, UENO, Isao, 長谷川, 達也, HASEGAWA, Tatsuya 04 1900 (has links)
No description available.
45

The Stakeholders Using Strategy of Diversification for Taiwan's Business Transformation: Case on Air Conditioning Industry

Hung, Li-Yun 06 September 2012 (has links)
As environmental protection issue become the most hot global issues recently, Air Conditioning Industry has to face not only its own management and marketing problems, but also the responsibilities to environmental pollution. Thus, how to deal with the external pressure, the international regimes, and internal pressure become more and more important toward Air Conditioning Industry. How could Air Conditioning Industry take balance between international regimes and its own growth and profit? In addition, it also briefly discusses how Air Conditioning Industry could use its own resource and the strategy of diversification to create different road, making a high pollution industry transform to a green industry. Thus, this study is divided into external and internal factors which make AC industry have to change by strategy of diversification, and cases studying of how Air Conditioner transform itself to fit in the external rapidly changing world. The transformation relies on the effort and cooperation of stakeholders of government, association, and enterprises. Consequently, how these stakeholders achieve the goals on development of Taiwan's heat pump market might be more and more important on Air Conditioning Industry's future.
46

A study of heat pump fin staged evaporators under frosting conditions

Yang, Jianxin 30 September 2004 (has links)
This dissertation provides a detailed description of the research work completed on fin staged heat exchangers. The effects of staging fin on the frosting performance of heat pump evaporators and the whole heat pump system have been studied experimentally and theoretically. Frost degrades the performance of fin-and-tube outdoor coils as well as the whole heat pump system. The objective of the experimental part of this study was to investigate the effects of the staging fin on the frost/defrost performance of heat pump outdoor coils under different operating conditions. To accomplish this objective, a series of frosting tests was conducted on an off-the-shelf heat pump system with five (three two-row and two three-row) evaporators over a range of outdoor temperatures and humidities and a range of airflow rates typical of those found in residential sized heat pumps. Performances of the heat pump unit with baseline or fin staged outdoor coils at either frosting or steady-state test conditions are compared and analyzed. Experimental data showed that for a given tworow heat pump outdoor coil operating at the standard ANSI/ASHRAE 35 °F (1.7 °C) frosting conditions, fin staging increased cycle time and COP. There was a small decrease in peak capacity at lower initial airflow rates. At a lower temperature of 28 °F (2.2 °C), cycle time continued to be enhanced with fin staging, and cyclic COP was within 5% of the base case when fin staging was used. In the second step of this work, an analytical model to simulate the performance of both the baseline and fin staged heat pump coils under frosting conditions was developed based on fundamental heat and mass transfer principles. The transient performance of the frosted evaporator was analyzed with the quasi-steady state approach. The section-by-section evaluation scheme was combined with the tubeby- tube approach to model the mass transfer process in the frost formation module. The two-dimensional fin surface was divided into a number of parallel non-overlapping sections. Each of the sections was the calculation unit for the mass transfer. Methods for calculating the airside heat transfer coefficient and friction factor were developed and applied to the simulation model of the fin staged coil. To verify the validity of the frosted evaporator model, the frosting performance of three two-row coils at the same test conditions was simulated and compared with experimental data. The frosted evaporator model appeared to provide satisfactory simulation of the fin-and-tube heat exchanger during the frost buildup process. Comparisons with the test data indicated that the model could capture the trends of the coil capacity, pressure drop, airflow and frost growth. The model also provided a variety of other simulation results including frost mass accumulation, air velocity inside coil, air and refrigerant outlet state, and so on. Overall, the numerical results were in reasonable agreement with the test data under different frosting operation conditions.
47

The Monitoring and Evaluation of Geothermal Systems

Maynard, Whitney E. 22 October 2010 (has links)
With the heightened importance of green engineering in today’s society, harnessing the Earth’s internal energy has become ever more important. Specifically, the use of geothermal heat pumps as a means of heating and cooling homes and municipal buildings is on the rise. However, due to the high cost of installation and limited amount of research conducted, geothermal systems in the State of Florida have yet to meet their potential as an alternative heating and cooling source. With Florida’s relatively constant ground temperature of 72 °F, an above average temperature gradient for both heating and cooling of indoor areas is provided. To this end, this thesis investigates different geothermal systems and their ability to utilize ground energy storage. To conduct this research, four different geothermal systems were installed and monitored over a period of one year. Testing of the installed systems monitored not only overall efficiency, but also the soils reaction to heightened energy input. Conclusions and recommendations are made as general design parameters for vertical column geothermal well systems in the state of Florida.
48

REDUCTION OF THE COSTS IN A HOUSE IN VALBO THAT USES ELECTRICITY AS ENERGY SOURCE : Study of the installation of a heat pump or connection to the district heating

OrdeÑana, Ianire January 2008 (has links)
The analyzed building in this project is located in Valbo, 9016 Stiftelsev 6. This house is a property of Gavlegårdarna, and it is being used as a house for disabled people. The building consists on five apartments, with one patient in each apartment. Some social workers help those patients in everything they need, making their living in the house as easy as possible. The aim of this project is to find out the best option of reducing the energy consumption in this house. There are some alternatives to reduce the energy or the energy costs as; efficiency measures, load management and energy conversion. This project is focused on the energy conversion for reducing the energy consumption. As it is the best option for obtaining a considerable reduction in the annual costs. First of all the energy balance of the house is analyzed. By studying the energy balance it is possible to find out how the energy consumption of the house is divided. On one hand there is the heat supplied and on the other hand the heat losses. As it was said before this project is focused in the reduction of the energy consumption by means of converting to another energy supplying method. Two alternatives have been studied: the installation of a heat pump and the connection to the district heating of Gävle.
49

Energy audit and saving analysis of a building : Study of heat pump installation and district heating connection

Urtasun, Cristina January 2008 (has links)
The object of analysis in the present document is a residential house in Sätra. This building has a hydronic space heating system with radiators spread around the house and a heating recovery system ventilation which also use water for reheating. Water for space heating, ventilation and hot tap water is nowadays heated in an electric boiler.The aim of this project is to make a diagnosis of the current situation, evaluate different alternatives for supplying hot water to the house, and to study costs and possible savings by comparing the actual facilities with the proposals done.
50

Environmental and techno-economic analysis of ground source heat pump systems

Hanova, Jana 11 1900 (has links)
Climate change stabilization requires an unprecedented effort to change our current approach to energy production and consumption. While rising energy prices are drawing increased attention to reducing energy demand, heightened concern about the environmental consequences of fuel choice requires that this demand be met at lower emission levels. In Canada, the realization of commitments to our GHG emission goals entails reducing residential energy use - a sector responsible for close to 20 percent of end-use energy consumption. This study focuses on the energy demand and emission levels of space and water heating, since these two components comprise 76 percent of residential energy demand. Ground source heat pumps (GSHPs) are a technology that provides heating at 25 to 30 percent of the energy consumed by even the most efficient conventional alternatives. GSHPs have been identified as the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available. However, their drawbacks have been high capital costs, and uncertainty about whether the electric power used by heat pumps has higher system-wide emissions. This thesis delineates how adoption of GSHPs in the residential sector can help align Canada’s technology choices with commitments made to the Kyoto Protocol. The manuscripts delineate conditions under which GSHP systems achieve the largest net emission reductions relative natural gas, heating oil, and electric heat counterparts. Electricity generation methods and emissions embodied in inter-provincial and international electricity trade are shown to significantly affect the emission savings achievable through GSHP. The thesis quantifies how relative fuel prices influence annual operating savings that determine how rapidly the technology can achieve payback. This analysis reveals GSHPs to hold significant potential for substantial GHG reductions at a cost savings relative to conventional alternatives; the time horizons for payback are as short as nine years for average-sized homes, and significantly shorter for larger homes.

Page generated in 0.1178 seconds