One of the legislative regulations aiming at reduced energy consumption in the European Union, is (EC) 640/2009 that imposes requirements of the efficiency of electric motors sold in the Union. This study aimed at examining the effectiveness of these legislative requirements. To illustrate the opportunities of reducing energy consumption by the introduction of more efficient motors, an efficiency measurement of electric motors that drive the fuel feed system in a cogeneration plant in Nybro was intended to be carried out. This was to enable a comparison between the efficiency of existing motors with motors which comply with the efficiency levels in (EC) 640/2009 and to calculate how much the energy consumption would decrease in this energy system if more efficient motors were introduced. The planed measurements could not be carried out to give a reliable result because the plant suffer from the same problem as many other industries in the EU, which is that the motors in this energy system are oversized and operate at low loads. Oversized motors do not operate at their rated efficiency and therefore a comparison of existing motors and motors that comply with the efficiency requirements in (EC) 640/2009 fails to give a correct result, since they would not operate at their rated efficiency if they were installed in this energy system due to the efficiency drop at low loads. Instead the load factor was determined with the Input Power Estimation Method that showed that all motors were operated far below their rated power, thus making this an inefficient energy system. This is a common problem, and an impediment for the directive to achieve its full potential energy savings because the efficiency of motors drops substantially if they are operated below their rated power. The results show that guidelines to avoid motor misapplications is just as important as raising the efficiency of electric motors. In the studied case higher energy savings can be achieved by replacing the tested motors to smaller motors instead of introducing new motors of the same size with a higher efficiency.

M. Tech. Mechanical Engineering. / Objectives of this research is to investigate the theoretical performance of the heat pump water heating system using R134a and R404A; to investigate effects of superheating and sub-cooling on the COP and energy consumption of the heat pump system; and to validate the theoretical findings with the experiment results, using the selected environmentally friendly refrigerants.

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy

The specific aim of this study was to advance the development of the Minimally Structured & Modular Vertical Farm (MSM-VF), an original concept developed at The University of Arizona, by designing a specific modular unit made of a transparent-walled modified standard shipping container for use in climate locations represented by Los Angeles and New York City. The conclusions of the study included: (1) A workable range of temperatures (15 to 30°C) for cultivating tomato in Los Angeles and New York City could be achieved in a transparent-walled MSM-VF shipping-container modular unit by using a cover material of low density polyethylene (LDPE) and a heating, ventilating and air conditioning (HVAC) system with an airspeed of 2 m/s, inlet angle at 60° and outlet position located at the top of the back wall; (2) A workable range of temperatures (15 to 27°C) for cultivating lettuce in Los Angeles and New York City could be achieved by using a cover material of LDPE and an HVAC system with an air speed of 4m/s, inlet angle at 60° and outlet position located at the bottom of the back wall; (3) The annual energy demands of the plastic-walled MSM-VF shipping-container modular unit were far less than those for the opaque-walled control plant-factory unit in all cases, except in the one case of growing tomato in New York City. Still, in this one exception, the annual energy demand of growing tomato in New York City in the plastic-walled MSM-VF shipping-container modular unit of 557.65 kWh/m² (versus 325.34 kWh/m² for the opaque-walled control plant-factory unit) was significantly lower than that of 711.91 kWh/m², which was the average for 164 greenhouses occupying a total of 16444 m² operated by the Cornell University Agricultural Experiment Station (CUAES) in the state of New York (CUAES Greenhouses); and, (4) The annual energy demands of the plastic-walled MSM-VF shipping-container modular unit were either significantly lower or for one case approximately the same (773.84 kWh/m²) as that of the 711.91 kWh/m² for the New York greenhouses. By contrast, the annual energy demands of the opaque-walled control plant-factory unit significantly exceeded that of the 711.91 kWh/m² for the New York greenhouses by 170% for Los Angeles and by 126% for New York City, both for growing lettuce. The foregoing results provided significant and reasonable basis for the practicability of Minimally Structured & Modular Vertical Farms made of plastic-walled shipping-container modular units in Los Angeles and New York City as well as in many other mega-cities around the world with similar climates.

No description available.

Power is one of the today’s major constraints for both hardware and software design. Thus the need to understand the statistics and distribution of power consumption from a hardware and software perspective is high. Power models satisfy this requirement to a certain extent, by estimating the power consumption for a subset of applications, or by providing a detailed power consumption distribution of a system. Till date, many power models have been proposed for the desktop and mobile platforms. However, most of these models were created based on power measurements performed on the entire system when different microbenchmarks stressing different blocks of the system were run. Then the measured power and the profiled information of the subsystem stressing benchmarks were used to create a regression analysis based model. Here, the power/energy prediction accuracy of the models created in this way, depend on both the method and accuracy of the power measurements and the type of regression used in generating the model. This work tries to eliminate the dependency of the accuracy of the power models on the type of regression analysis used, by performing power measurements at a subsystem granularity. When the power measurement of a single subsystem is obtained while stressing it, one can know the exact power it is consuming, instead of obtaining the power consumption of the entire system - without knowing the power consumption of the subsystem of interest - and depending on the regression analysis to provide the answer. Here we propose a generic method that can be used to create power models of individual subsystems of mobile platforms, and validate the method by presenting an empirical power model of the OMAP4460 based Pandaboard-ES, created using the proposed method. The created model has an average percentage of energy prediction error of just around -2.7% for the entire Pandaboard-ES system.

Worldwide, renewable energy systems are booming with reliable distributed generation (DG) technologies to help fuel increasing global energy consumption and mitigate the corresponding environmental problems. High cost and low efficiency are major problems for such systems using traditional buck inverters with line-frequency transformers. This thesis has proposed a novel single-phase single-stage buck-boost inverter suitable for cost-effective small DG systems. The inverter was analyzed from the angle of energy exchange and transfer with two current control schemes, DCM and CCM. Sinusoidal PWM (SPWM) control method, based on DCM, was discussed in details with steady state analyses, computer simulations, and laboratory tests. A concise model with underlying equations was derived to represent the physical behavior of proposed inverter. Closed-loop SPWM control was simulated and verified to have fast dynamic response and good tracking performance with robustness and insensitivity to dc input fluctuations, ac grid variations, and component parametric uncertainties. Other control strategies were also investigated from the critical DCM, CCM, or energy approach to either increase the fundamental output or further improve the performance. Comparisons demonstrated that SPWM was preferred control method with low output THD, reduced switching losses, and simple implementation. Therefore, it is concluded the proposed inverter provides a low-cost and high-efficient solution for small DG systems with low component count, minimal dc and ac filtering requirements, and improved performance.

No description available.

This thesis consists of four essays. The first essay looks at pollution taxation under capital mobility, and analyzes the role of pre-commitment by countries to their pollution tax rate. A polluting firm sells its product in two countries, and can locate and produce in a single country or in both countries. Due to the discrete-choice nature of the firm's location problem, the countries' welfare functions are discontinuous in their pollution tax rate. We show that when the countries cannot pre-commit to their pollution tax, the firm can still engender tax competition between them by strategically locating in both the countries. Moreover, pre-commitment pollution taxation may not be welfare improving for the countries, although it always makes the firm better off. / The second essay studies the effect of liberalization on corruption. Corruptible inspectors enforce an environmental regulation on firms, and are monitored by an honest regulator. Liberalization not only increases the variety of goods and the marginal utility of accepting a bribe, but also puts pressure on the regulator to curb corruption. The interaction of these two effects can cause corruption to initially increase with liberalization, and then decrease beyond a threshold. Moreover, equilibrium corruption is lower when the regulator is able to pre-commit to her monitoring frequency. / The third essay analyzes optimal labeling (information revelation) procedures for hidden attributes of credence goods. Consumers are heterogeneous in their preference for the hidden attribute, and producers can either self-label their products, or have them certified by a third party. The government can impose self or third-party labeling requirements on either the "green" or the "brown" producers. When corrupt producers can affix spurious labels, the government needs to monitor them. A mandatory self-labeling policy is shown to generally dominate mandatory third-party labeling. / The fourth essay develops formulas for computing the economy-wide energy intensity decline rate by aggregating sectoral energy efficiency improvements, and sectoral shifts in economic activities. The formulas are used to (i) construct plausible scenarios for the global rate of energy intensity decline, and (ii) show the restraining role of the "electricity generation" sector on the energy intensity decline rate.

Buildings energy consumption is rising continuously with massive urbanization progress, which then results in high greenhouse gas emission. A standing example is the urbanization process going on in the south-west part of China. Much has been discussed for improving building energy performance. However, to take another point of view, renewable energy source for buildings is a solution worth considering, for instance STES, which gains thermal energy from the sun, delivers it to buildings for space heating and hot tap water, also restores the solar energy in hot seasons in the storage system for the need of cold season.The aim of this paper is to couple the technology of STES with practical situation, explore the possibility of applying STES in south-west of China. This thesis work takes an estimation approach to weigh the possibility. The building project studied in this thesis is a campus project in the city of Guiyang, one of four major cities in the region of south-west China.Case study involves existing STES projects in Munich Germany and Anneberg Sweden, the performance evaluation of the Anneberg project is later to serve as an example in system gain & losses proportion, to guide the estimation work of the campus project.The estimation conclusion is drawn based on a cross-sectional analysis method, take the technology of STES, the practiced STES project and building projects in China as three loops visually, and observe how much they overlap each other. Behind the visual illustration, the overlapping is assessed with several factors, for instance possibility of storage system at location, possible STES performance and solar irradiation condition at site location etc. If most of these factors are checked to be “Ok” or “Good”, then the overlapping area is considered “large” enough, and therefore suggests a decent chance to implement STES system in the south-west China.A solar gain and sunlight simulation from a new police station energy consumption report assists in calculating the possible solar gain for the campus project, as the very close distance between these two sites (30 km) promises them the very similar solar irradiation condition. While the energy consumption of the studied campus project offers the energy demand for space heating and hot tap water in the need of 19,000 students, which is to be evaluated as the task of the STES system in the estimation work. Both building project reports are filed by GARDI (Architecture design research institution of Guizhou).Some key factors have been calculated and estimated, the heat demand of the studied campus project in Guiyang is 5,558 MWh/year, and the possible solar gain of this campus complexity is 4,900 MWh/year based on the gain & losses proportion of the Anneberg project evaluation. Due to the very different climate condition of Guiyang and Anneberg, as well as other uncertain factors such as effective roof area, solar collector efficiency, a sensitivity analysis evaluated the result with different parameters in changes of percentage. Final results in the changes of effective roof area at 80% and 85 %, borehole losses at 50% and 45%, available solar gain at 38%, STES system is shown to be capable of providing sufficient heat to buildings. If the heating demand and hot tap water, in the case of the campus project alone are all covered by STES system, there will be a reduction in CO2 emission of 5,368 tons/year.Cross-sectional analysis concludes four out of eight factors checked as “Good” and two as “Ok”, other two as “Unsure”. Other three cities (Chengdu, Kunming, and Chongqing) are brought to comparison later regarding climate condition. Besides Guiyang, two out of three are evaluated to have potential of STES implementation according to their sun hours, annual average temperature etc. STES system is estimated to be possible for implementation in south-west of China as the conclusion.