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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.
1

The Design Analysis and Experimental Investigation on School Building Energy Conservation

Shiao, Ay-ling 21 June 2003 (has links)
Due to the energy crisis in 1970, the energy saving is more important for the human civilization. The energy-saving policy is important for the economic growth and competition of Taiwan. The energy of daily life and business consumes 17% of the total energy, especially the air conditioning of architectures on the peak hours occupying a third in summer. So the building energy-saving policy is the most important in Taiwan. The main of theme building energy saving is not only to save energy but also to consider the comfortable and healthy of the living environment. So that, the optimal design of the building energy saving of commercial buildings in Taiwan has been established in this paper. In this study, theoretical analysis and a full scale experiment has been performed to validate this design. Results showed this design is suitable for the NPTC building in the weather condition of south Taiwan, which also complies with the energy code of Taiwan.
2

The Application of the HEMS Energy Conservation Strategies in Taiwan

Chang, Kai-chiang 13 July 2009 (has links)
ABSTRACT The HEMS system has been gaining global attention due to its huge potential for home application in conserving energy. It is the goal of this research to study to analyze: 1. The Intelligent Operational Strategies under local Weather Conditions 2. Full-scale Experimental Investigation of the HEMS system, including the HVAC and Lighting Controls 3. Energy Savings Effect of each HEMS strategy developed and its Economic Feasibility The experimental result indicated that the HEMS system can be established efficiently in applying: For Air-conditioning Systems: Intermittent Ac PMV-assisted AC Mode DSM-controlled AC mode Predictive Control AC Mode Free-cooling Mode, and For Lighting Systems : Lighting on Demand Mode Task Lighting Sequential Control Lighting Daylighting Humane-sensored Lighting The experimental result indicated that over 30% energy savings can be experienced with huge potential for wide engineering applications.
3

An Experimental Investigation of End Plate Connections

1970 July 1900 (has links)
The results of an experimental investigation of end plate connections of various thicknesses welded to 10 WF21 and 12 WF27 beams and connected to various stiffened and unstiffened 8 WF columns are reported. Moment-rotation curves have been obtained for all connections tested and these have been compared to determine the effects on connection performance of the parameters of end plate thickness, column section, and column stiffener plates. Yield beam lines, representing first yield in a uniformly loaded beam, were drawn to obtain the connection moment at the yield beam line. The value of this moment indicated that the connections behaved semi-rigidly and was used in the comparison of various connections. It was observed that the thicker the end plate, the more rigid the connection and the greater the effect of column stiffeners on the rigidity of the connection. For an end plate connection of a particular width and depth connected to a particular column, there is a limiting moment which such a connection can sustain at the yield beam line, regardless of the thickness of end plate used. This limiting effect is due to deformation of the column section, specifically, of the column flange. Column stiffener plates increased the rigidity of all connections primarily by restraining the deformation of the column flanges adjacent to the tension flanges beams. Column stiffeners prevented column web bucking, however the column web buckles which developed in these tests were initiated at rotations greatly exceeding those expected in structural forms.
4

Experimental investigation of an R134a based organic Rankine cycle

Hoque, Shaikh Md Emdadul 01 August 2011 (has links)
This thesis research aims to develop an improved, efficient, low-capacity heat engine, running on an Organic Rankine Cycle (ORC) to generate power. The ORC is driven by low or moderate temperature heat sources, such as; renewable energy in the form of a hot gas derived from biomass/biogas/biofuel combustion streams, waste heat recovery, process heat recovery, etc. The ORC is more suitable and flexible than a conventional steam Rankine cycle, especially when it is applied to low power range. In this research, an extended surface heat exchanger is used to boil the pressurised working fluid, R134a, using a hot air as heat source. The expander used is a scroll type, coupled to a generator, which is able to produce maximum 1.6 kW output. Experimental data of the heat engine are measured under different operating conditions and utilized in the analysis and comparisons. Power generation under various conditions is investigated in order to determine the optimum performance parameters for the heat engine. The isentropic efficiency of the expander is found to be over 40% and reaches 80% for the improved expansion conditions. For the boiler, it is determined that the overall heat transfer coefficient multiplied with the heat transfer area is around 150 W/K. The energy efficiency of the experimental ORC is around 3% for hot air as the low temperature heat source at about 105oC where exergy efficiency reaches 22%, respectively. / UOIT
5

Design Analysis and Experimental Investigation of Smoke Management and Egress System of a Large Shopping Mall

Yang, Chih-Sheng 30 April 2003 (has links)
ABSTRACT Almost people hurt or die because of heavy smoke when the building fires. Smoke Management is to keep the smoke in the limited zone or to change its direction and to keep the ways which the people escape bright. It is convenient for fireman to save them and to keep their life and to reduce the money loss. In the developed country of the world, smoke management design is one of the most important factors to affect egress system of the building. Effective smoke management design is to avoid the smoke diffusing or descending and to make the people have enough time to escape. The combination of smoke management and egress system using performance-based fire safety design should be developed safely and economically. In Taiwan,we haven¡¦t the proper law of smoke management and egress system about the atria of the large space. So we must progress the computer simulation about smoke management and egress system and then use full-scale experiment to perform. The major terms of the content are: 1.the optimal distribution zone analysis of smoke management of the building. 2.to design and to analyze smoke management of the atria. 3.the combination of design analysis of smoke management and egress system. 4.full-scale experimental investigation. We hope that the performance-based fire safety design method about smoke management and egress system of the large shopping mall could be the excellent model and enchance the safety of the building in Taiwan.
6

Modeling of shrinkage porosity defect formation during alloy solidification

Khalajzadeh, Vahid 01 May 2018 (has links)
Among all casting defects, shrinkage porosities could significantly reduce the strength of metal parts. As several critical components in aerospace and automotive industries are manufactured through casting processes, ensuring these parts are free of defects and are structurally sound is an important issue. This study investigates the formation of shrinkage-related defects in alloy solidification. To have a better understanding about the defect formation mechanisms, three sets of experimental studies were performed. In the first experiment, a real-time video radiography technique is used for the observation of pore nucleation and growth in a wedge-shaped A356 aluminum casting. An image-processing technique is developed to quantify the amount of through-thickness porosity observed in the real-time radiographic video. Experimental results reveal that the formation of shrinkage porosity in castings has two stages: 1-surface sink formation and 2- internal porosity evolution. The transition from surface sink to internal porosity is defined by a critical coherency limit of . In the second and third experimental sets, two Manganese-Steel (Mn-Steel) castings with different geometries are selected. Several thermocouples are placed at different locations in the sand molds and castings to capture the cooling of different parts during solidification. At the end of solidification, castings are sectioned to observe the porosity distributions on the cut surfaces. To develop alloys’ thermo-physical properties, MAGMAsoft (a casting simulation software package) is used for the thermal simulations. To assure that the thermal simulations are accurate, the properties are adjusted to get a good agreement between simulated and measured temperatures by thermocouples. Based on the knowledge obtained from the experimental observations, a mathematical model is developed for the prediction of shrinkage porosity in castings. The model, called “advanced feeding model”, includes 3D multi-phase continuity, momentum and pore growth rate equations which inputs the material properties and transient temperature fields, and outputs the feeding velocity, liquid pressure and porosity distributions in castings. To solve the model equations, a computational code with a finite-volume approach is developed for the flow calculations. To validate the model, predicted results are compared with the experimental data. The comparison results show that the advanced feeding model can accurately predict the occurrence of shrinkage porosity defects in metal castings. Finally, the model is optimized by performing several parametric studies on the model variables.
7

Development of BEMS Diagnostic and Intelligent Expert Technology for Air-conditioning Systems

Dai, Chi-fu 11 June 2012 (has links)
When central HVAC systems are under commercial operation, all operational parameters, including chilled water supply temperature, return water temperature, chilled water flow rate, and power consumption as the key factors in affecting system energy efficiency.However, in Taiwan there is still lacking of the regression equations of chillers under local weather conditions, and has to rely on manual operation based on experiences. This is also the major short-comings in implementing TAB, and is the best way to renovate the green buildings to make them more intelligent. In this study, theoretical analysis and experimental investigation will be applied simultaneously. In selecting cases from the BeeUp program, actual operational data including COP can be fitted into experimental model to facilitate TAB engineering via BEMS system, in achieving system efficiency. Through the execution of this project, it is identified that the exhibition buildings with 10 hours cooling load, can achieve 7% energy savings. The good result obtained in this project , including the thermal energy storage HVAC system and the heat pump system can be widely adapted to obtain significant energy conservation effect.
8

Experimental Investigations of Vortex Induced Vibration of A Flat Plate in Pitch Oscillation

Yang, Yi 2010 December 1900 (has links)
A bluff structure placed in a flowing fluid, may be subjected to vortex-induced vibrations (VIV). For a flat plate with only rotational degree of freedom, the VIV is rotational oscillation. Based on the experimental investigation, vortex-induced oscillation of the plate is studied. The Strouhal number is measured from the stationary plate in a low speed steady wind tunnel. A set of vibration tests are conducted to investigate the relationships between shedding frequency and vibration frequency. “lock-in” phenomena is observed with and without large amplitude. An empiricalanalytical model via introducing a nonlinear van der Pol oscillator is developed. This thesis investigates the “lock-in” phenomena of a flat plate in pitch oscillation. Results from wind tunnel experiments on a flat plate indicate the “lock-in” is frequency “lock-in”, resonance which appears large response amplitude occurs in the “lock-in” regime and may be influenced by “lock-in” phenomena.
9

Development of a rig and testing procedures for the experimental investigation of horizontal axis kinetic turbines

Lartiga, Catalina 30 April 2012 (has links)
The research detailed in this thesis was focused on developing an experimental testing system to characterize the non-dimensional performance coefficients of horizontal axis kinetic turbines, including both wind turbines and tidal turbines. The testing rig was designed for use in a water tunnel with Particle Image Velocimetry (PIV) wake survey equipment to quantify the wake structures. Precision rotor torque measurement and speed control was included, along with the ability to yaw the rotor. The scale of the rotors were purposefully small, to enable rapid-prototyping techniques to be used to produce many different test rotors at low cost to furnish a large experimental dataset. The first part of this work introduces the mechanical design of the testing rig developed for measuring the output power of the scaled rotor models with consideration for the requirements imposed by the PIV wake measurements. The task was to design a rig to fit into an existing water tunnel facility with a cross sectional area of 45 by 45 cm, with a rotor support structure to minimize the flow disturbance while allowing for yawed inflow conditions. A rig with a nominal rotor diameter of 15 cm was designed and built. The size of the rotor was determined by studying the fluid similarities between wind and tidal turbines, and choosing the tip speed ratio as a scaling parameter. In order to maximize the local blade Reynolds number, and to obtain different tip speed ratios, the rig allows a rotational speed in the range of 500 to 1500 RPM with accurate rotor angular position measurements. Rotor torque measurements enable rotor mechanical power to be calculated from simulation results. Additionally, it is included in this section a description of the instrumentation for measurement and the data acquisition system. It was known from the outset that measurements obtained in the experiments would be subject to error due to blockage effects inherent to bounded testing facilities. Thus, the second part of this work was dedicated to developing a novel Computational Fluid Dynamics (CFD) methodology to post-process the experimental data acquired. This approach utilizes the velocity field data at the rotor plane obtained from the water tunnel PIV test data, and CFD simulations based on the actuator disk concept to account for blockage without the requirement for thrust data which would have been unreliable at the low forces encountered in the tests. Finally, the third part of this work describes the practical aspects of the laboratory project, including a description of the operational conditions for turbine testing. A set of preliminary measurements and results are presented, followed by conclusions and recommendations for future work. Unfortunately, the water tunnel PIV system was broken and thus unavailable for more than a year, so only mechanical measurements were possible with the rig during the course of this thesis work. / Graduate
10

The experimental investigation of buoyant flows in inclined differentially heated cavities

Esteifi, Khaled January 2011 (has links)
Buoyant flows are present in nature and also in many engineering applications,from domestic heating to the cooling of nuclear power plants. This experimental study focuses on the effects of angle of inclination on buoyancy-driven flows inside tall, rectangular, differentially-heated cavities. The objective is to produce detailed local flow and thermal data, which will advance our understanding of the flow physics and also provide CFD validation data. It considers a 2.18m × 0.52m × 0.0762m cavity, resulting in an aspect ratio of 28.6, with its two opposing long walls maintained at constant but different temperatures, while all the remaining walls are thermally insulated. The Rayleigh number, based on the temperature difference and spacing of the long sides, is 0.86 x 106 for most cases and the working fluid is air (Prandtl number0.71). Experimental data for the flow and the thermal fields, using laser Doppler anemometry and Chromel-Alumel thermocouple traverses respectively, are presented for the cavity inclined at 60° and 15° to the horizontal, for both stable (the hot surface being the upper surface) and unstable (the hot surface the lower one) orientations. The 15° stable case is investigated at a higher Rayleigh number of 1.54 x106 and some additional data for the 15° unstable case are also presented at this high value of Rayleigh number. Comparisons with the measurements of Betts and Bokhari [1], for the same cavity at the vertical position, are also included. For moderate angles of inclination, the flow is two-dimensional and the effects of inclination are primarily confined to the fluctuating fields. For large angles of inclination, the flow becomes three-dimensional. In the unstable 15° angle of inclination case, a set of four longitudinal vortices are formed over the entire length of the cavity, with four counter-rotating re-circulation cells within the cross-section parallel to the thermally active walls. The enhanced mixing at 15° unstable inclination leads to uniform temperature in the cavity core and thus only minor deviations from two dimensionality in the thermal field. A modest rise in Rayleigh number, in the 15° unstable case, does not affect the mean motion, but causes an increase in the normalised turbulence intensities, which in turn leads to a more uniform temperature within the cavity core and a practically two-dimensional thermal field. The stable 15° angle of inclination case, surprisingly, leads to the formation of two longitudinal vortices and two re-circulation cells. The lack of mixing, in the 15° stable case, leads to more noticeable three-dimensional thermal field. The thesis includes a full set of flow and thermal predictions and also spectral analysis of thermal fluctuations, which show a significant effect of the angle of inclination on both the power density level and the ranges of frequencies involved.

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