• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 101
  • 58
  • 30
  • 22
  • 12
  • 11
  • 8
  • 8
  • 6
  • 6
  • 5
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 298
  • 298
  • 53
  • 47
  • 47
  • 44
  • 39
  • 36
  • 35
  • 34
  • 29
  • 28
  • 28
  • 27
  • 26
  • 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.
1

The management and implementation of energy-thrift in hospitals

Adderley, A. E. January 1989 (has links)
The 1984 Auditor Genera1's report on energy~thrift in the Health Service claimed that energy~thrift programmes in hospitals were not achieving their performance targets. In order to determine the reasons for this failure, twenty hospital energy~audits were analysed. It was discovered that the two principle factors impairing the performance werez- (a) The thermal conflict between thrift measures implemented on the same thermal system, and, (b) inefficient implementation strategies. In order to investigate the influences of thermal conflict and implementation strategy on the out~comes of energy~thrift programmes,four objectives were defined:~ (i) To develop a computer model which was capable of simultaneously thermally modelling the implementation of energy-thrift measures on several hospital sites. (ii) To use the model to predict the thermal and financial out~comes of various implementation strategies. (iii) To test the sensitivity of the outrcomes to changes of unit fuel prices and capital costs, and, (iv) to compare the predicted results with those actually obtained. Data from four hospital sites and ninety thrift measures were entered into the model for analysis. It was deduced that a law of diminishing returns existed between capital investment and annual savings and that thermal conflict was responsible for an average annual financial loss of 15.5%. The financial returns on the capital invested were considerably enhanced (in one case by 3ÖØ%) by spreading the financial resources over all four sites rather than by concentrating the same capital outlay on a single site. Furthermore it was discovered that there was a level of capital investment that yielded an optimal net present value over the selected project life. The programmes were more sensitive to reductions of unit fuel prices than increases of capital costs. Most of the thrift programmes remained viable (N.B. N.P.V. > Ø using the public sector discount rate _of 5% and a project life of 5 years) after the unit fuel prices had been reduced by 5Ø% of their 1985 levels. When the results of the implemented programmes were compared with the models' predictions, the accuracy of the estimated savings ranged from a 4.5% under-estimate t 2.5% over-estimate. The software was designed to find the best-fit Ventilation rate and`base temperature for each hospital site and for each thermal zone within the hospital. When the post-implementation assessments of overall air-change rate and site base temperature were compared with those predicted, the model detected changes closely matching the predictions. â The results indicated that the technique developed in this thesis has potential as a monitoring and targeting system as well as a thermal model for predicting the out- comes of energy-thrift programmes.
2

An Investigation of Window and Lighting Systems using Life Cycle Cost Analysis for the Purpose of Energy Conservation in Langford Building A at Texas A&M University

Hwang, Hea Yeon 2011 May 1900 (has links)
Langford Building A forms part of the Langford Architectural Complex at Texas A & M University. Inefficient lighting fixtures and single pane windows in Langford Building A contribute to a considerable portion of the total cost of energy for this building. In the Southwestern United States, a building's windows can be responsible for a significant loss of energy. The windows and inefficient light bulbs can result in high utility costs and high labor charges from more frequent lighting maintenance than that required for efficient lighting. In Langford Building A, window system energy efficiency has not been improved since the building was constructed in 1977. This paper investigates the economic feasibility of using efficient lighting and window systems in Langford Building A. The cost for windows and new lighting tubes was analyzed and compared by using Life Cycle Cost Analysis. The payback periods, determined in this analysis, showed that more efficient lighting and window systems would reduce costs. As results of this analysis, the window film and LED lighting tube reduce building life cycle cost and short payback periods than other alternatives.
3

Heat pump assisted distillation with an external working fluid

Supranto, S. January 1986 (has links)
No description available.
4

Energy-efficiency building envelope technologies

Xiao, Naiyuan January 2014 (has links)
In recent years, the excessive emission of greenhouse gas CO2, it causing globalwarming, already poses a serious threat to human survival. The problem catches theattention all over the world, and promoting the development of building energyefficiency. In order to the sustainable development of human beings, in 1992 theUnited Nations framework convention on climate change (UFCCC) organizationpublished the Kyoto protocol. In the Kyoto protocol, the European countriescommitted that during 2008 and 2012 they would reduce the amount of greenhouseemissions to 8% compare to 1990.[2] Building envelope technologies can helphouseholder reduce the energy consumption use in the building. Building envelopetechnologies used in the project Brogåden – Alingsås which save the energyconsumption from 204 kWh/ m2a to 95 kWh/ m2a in Sweden. While the cost just838SEK/m² or 8% of the total building costs. In China the envelope technologies usedin the project student apartment in Shandong building university save the energyconsumption about 72% compare with the old student apartments.
5

Energy conservation in the zinc-lead blast furnace

Cochrane, R. F. January 1985 (has links)
No description available.
6

Control of rectifier equipment used for electrostatic precipitation

McLellan, P. G. January 1989 (has links)
No description available.
7

A Knowledge-based Energy-saving Approach to PWM Control of a Novel Integrated Pneumatic Valve

Aghighi, Hanieh January 2008 (has links)
As manufacturers, the automotive industry, and many other sectors face an increasingly competitive global business environment; they seek opportunities to reduce production costs by reducing energy consumption. Energy costs have become one of the fastest-rising expenses of doing business, and the industrial sector is rushing to implement new energy conservation initiatives. Pressurized air, as an important source of energy, has been widely used by various industries, providing simple solutions for automated lines. In this project, an Accumulator-Based Equalization (ABE) strategy was combined with a knowledge-based PWM (Pulse Width Modulation) protocol, and then incorporated into an integrated solenoid valve to increase the energy efficiency of pneumatic systems through the optimization of ow consumption. Modeling and simulation of the proposed system was carried out to assess the proposed ideas and reduce the cost of system developments. An experimental setup was constructed to assess the performance of the proposed strategy when implemented on configured pneumatic control valves. Equalization was performed at home positions of a typical linear actuator, where the chambers of the pneumatic actuators were momentarily connected to each other. Furthermore, during the extension and retraction, a knowledge-based PWM signal was applied to the valves to maintain the actuator dynamics in an acceptable posture. To obtain the knowledge-based PWM signal, an expert-fuzzy controller was designed to control the speed of the actuator. This knowledge-based protocol was based on fuzzy structures, which were implemented on the configured pneumatic valves in an open-loop fashion to decrease the amount of ow consumption without compromising the dynamic performance of the pneumatic actuators. The identified duty cycles profiles from the expert fuzzy controller were implemented on an open-loop system. It was observed that, while an open-loop system is used, the pressurized air can be saved about 20% under 50 N load and almost 10% under 150 N load. "Smoothness index" was defined as a measure of the piston motion smoothness when applying the proposed strategies. In addition to smoothness of the motion in the closed-loop control methods, the energy-saving results were compared to the results of the open-loop system and the performance under different conditions was evaluated.
8

A Knowledge-based Energy-saving Approach to PWM Control of a Novel Integrated Pneumatic Valve

Aghighi, Hanieh January 2008 (has links)
As manufacturers, the automotive industry, and many other sectors face an increasingly competitive global business environment; they seek opportunities to reduce production costs by reducing energy consumption. Energy costs have become one of the fastest-rising expenses of doing business, and the industrial sector is rushing to implement new energy conservation initiatives. Pressurized air, as an important source of energy, has been widely used by various industries, providing simple solutions for automated lines. In this project, an Accumulator-Based Equalization (ABE) strategy was combined with a knowledge-based PWM (Pulse Width Modulation) protocol, and then incorporated into an integrated solenoid valve to increase the energy efficiency of pneumatic systems through the optimization of ow consumption. Modeling and simulation of the proposed system was carried out to assess the proposed ideas and reduce the cost of system developments. An experimental setup was constructed to assess the performance of the proposed strategy when implemented on configured pneumatic control valves. Equalization was performed at home positions of a typical linear actuator, where the chambers of the pneumatic actuators were momentarily connected to each other. Furthermore, during the extension and retraction, a knowledge-based PWM signal was applied to the valves to maintain the actuator dynamics in an acceptable posture. To obtain the knowledge-based PWM signal, an expert-fuzzy controller was designed to control the speed of the actuator. This knowledge-based protocol was based on fuzzy structures, which were implemented on the configured pneumatic valves in an open-loop fashion to decrease the amount of ow consumption without compromising the dynamic performance of the pneumatic actuators. The identified duty cycles profiles from the expert fuzzy controller were implemented on an open-loop system. It was observed that, while an open-loop system is used, the pressurized air can be saved about 20% under 50 N load and almost 10% under 150 N load. "Smoothness index" was defined as a measure of the piston motion smoothness when applying the proposed strategies. In addition to smoothness of the motion in the closed-loop control methods, the energy-saving results were compared to the results of the open-loop system and the performance under different conditions was evaluated.
9

Thermal Models and Energy Saving Strategies for Rotational Molding Operations

Ghosh, Kalyanjit 09 July 2004 (has links)
Transient heat transfer phenomena in the rotational molding of plastic parts are modeled in this study. Natural convection and radiation from the furnace and flue gases to the mold housing are analyzed. Other models include transient heat transfer through the mold, single-phase conduction through the particulate plastic material prior to phase change, melting of the plastic and heating of the liquid pool. Subsequent staged cooling of the mold and solidification of the plastic using a combination of free and forced convection and radiation, are also modeled. The mold wall, melt, and solidified plastic regions are divided into a number of finite segments to track the temperature variation with time during the molding process. The corresponding variations in masses and thicknesses of the melt and solidified plastic regions are estimated. This information is used to estimate the energy consumption rates for various phases of the process. The model is applied to a specific molding process in a commercial rotational molding plant. Parametric studies of the effect of heating and cooling durations on the plastic temperatures and the energy consumption rates are conducted. These analyses provide insights about opportunities for optimization of the heating and cooling schedules to reduce overall energy consumption and improve throughput. The overall energy and gas consumption for the rotational molding process, taking into consideration the thermal mass of the auxiliary housing (steel) required to hold the molds, is estimated on a per-batch basis. In addition, a preliminary design for an alternative system for heating and cooling the molds using a high temperature heat transfer fluid (HTF) flowing through jackets integral to the molds is proposed.
10

Energy analysis for a snow-free surface : A technical analysis of the benefits of insulation under the heating pipes

Ying, Song January 2018 (has links)
Snow-free surfaces is needed for parking place, platform, and playground and even in city center square. With energy prices rising, energy saving is becoming a hot topic. Meanwhile environmental problems are becoming more and more serious, thus, the ways to saving energy is becoming an eye-catcher. So burring heating pipes underground has been a popular way to get ice-free surfaces. Using heating pipes for melting snow is much more efficient and more benefit for the environment comparing with using other methods.   In this project, an energy analysis of a football pitch with an area of 5000 m2 is carried out under a series of conditions between insulated and uninsulated construction. All calculations are done with the so-called finite element method (FEM), in the COMSOL. COMSOL is used for simulating and calculating the energy use with outdoor temperatures of -5 ºC and -10 ºC. Top layer materials concrete, grass and stone are also discussed. The ability of XPS and EPS insulation material is compared and noted. The models are divided into two parts, one is with snowfall and the other is without snowfall.   The results in the report shows that adding insulation under the heating pipe has significant energy saving potential. The surface with concrete layer has the best insulated ability, which can prevent more heat losses. The EPS insulated construction has a better performance in keeping more heat in the soil.

Page generated in 0.0877 seconds