No description available.

Determining residential airconditioning waste heat recovery system costs and savings is achieved using a computer program. A worksheet is designed to accept consumer data as an input to the program. The program features load and waste heat recovery calculations on a monthly basis. Economic criteria, including rate of return, present worth, and payback period are computed. Sensitivity of these criteria to fuel escalation and consumer discount rate is demonstrated. the program provides the user with both thermal analysis and economic analysis summary reports.

Growing concerns regarding climate change, the increase in demand for energy and the efficient utilization of energy have become of major interest in applications of heating and power generation. A large portion of the energy input to these applications is lost, due to their typical inefficiencies, in the form of waste thermal energy which, if captured and utilized, can offer an abundant source of energy for electricity generation and heating purposes. The use of thermoelectric generators (TEGs) of different designs in waste heat recovery applications has been pursued over the past few decades as the generation of electrical power using TEGs has become viable compared to other conventional systems at low temperatures. This study focuses on the implementation of an annular design for integrated TEG modules in a heat exchanger device for waste heat recovery and the investigation of the effect of different TEG design parameters on the device performance. The integration of the annular TEG design in the heat exchanger was studied using a developed numerical model to investigate the interaction between the heat transfer and the thermoelectric effects and evaluate the performance under specific operating conditions. The heat transferred from the exhaust to the water flow through the TEGs was modelled using a thermal network for the heat flow, coupled with an electrical circuit for the power output. The model was validated using experimental results of the first generation of the TEG device with good agreement (3-6 %) between the predicted and measured performance results: power output, efficiency and the exhaust and water flow temperatures. With the objectives of maximizing the power output and improving the power characteristics, a half annular TEG design was presented. It was able to generate the same power output with double the voltage and half the current, thus improved the power characteristics required for functional operation, compared to the full annular design. The effect of the annular TEG design dimensions on the device performance was studied for a multi-row heat exchanger using the numerical model. The results showed that a maximum power output can be obtained at optimum TEG diameter ratio and thickness. In addition, the TEGs performance was studied under different electrical connection configurations in series and in parallel. The series connection between TEG rows showed better power output characteristics with lower current output, minimal power loss due to temperature mismatch and higher voltage output. The effect of heat exchanger design considerations such as the axial heat conduction was also investigated using the numerical model and the results were compared with an ANSYS model for verification. Good agreement was demonstrated and the results showed a decrease in the total power output of multiple TEG rows when axial conduction of heat was allowed between the TEGs hot-side surfaces in the heat exchanger. A dimensions map was created for annular TEGs integrated in a heat exchanger combining the effects of varying the TEG diameter ratio and thickness on the power output. Further, a dimensionless design parameter (β) was introduced to locate the maximum power region on the map. Using the map as a design tool, the dimensions of the annular TEG modules in a heat exchanger were determined to maximize the power output under a typical current output constraint in order to improve the system power characteristics. Using the map, it was shown that the current output could be reduced by 46 % of its value at the maximum power available on the map and the resultant power output could be maintained at 98 % of its maximum value. This also resulted in a 48% reduction in the TEG material volume and an increased voltage output of the device. As a result, the power output was maximized, the current output was limited to reduce losses in the power management system components and material volume reduction was achieved which would increase the device power density and reduce its overall cost. / Thesis / Master of Applied Science (MASc)

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 120-121).

The shortage of energy supply against growing demand globally has caused seriously impact to all industries, dead or alive, especially for the energy intensified industries, like oil refinery (Petroleum) Iron and Steel making industries which has been confronting tremendously with pressing concern for survival. Even both industries are within traditional industrial factor, but represent as key and fundamental industries as relied on, by all industries of a Nation. Therefore, all the international enterprises dealing with high-temperature production have been striving for long-term supply & steady quality of raw material of energy. Under this circumstance, the enterprises shall be offering to find the measures for cost-down of energy consumed, and further utilize the waste gas and heat as generated out of the production, that would surely produce the efficiency of energy, and not only diminish the dependence on primary energy, it also can effectively reach the goal of ¡§Independence of Energy¡¨ and optimization for the control of energy cost. This study is adopting the case study of Company ¡§C¡¨, with the analysis of SWOT, Five-force Analysis, and Diamond Model by Michael Porter, to further analyze the overall environment and circumstance of energy intensified industries. So that, it might help to understand further the strength and weakness of the energy intensified industries of our nation. First of all, to proceed the survey for the application of waste heat recovery system to energy intensified industries, and secondly, the application of waste heat recovery system to energy intensified industries in Taiwan, to generate direct and indirect efficiency whether or not to escalate the overall competitiveness to face the global competition. This research recognize the No. 1 pressure & bottle neck of the energy intensified industry lies mainly in the insufficiency of energy supply, and the upcoming environmental protection is getting more conscious & concerned. Therefore, all the industrialized countries have moved further forward to reinforce the energy saving technology, and increase the efficiency of energy using, developing new generation of energy with more efforts. Adoption of Company ¡§C¡¨, has recognized the following benefit, after the introduction of Waste Gas Heat Recovery System: 1. Recovery of Waste Gas of Hot Blast Stove, reduction of COG use, to transfer the saved COG to down-stream, to substitute the expensive natural gas, which is benefit to Company ¡§C¡¨ in the respect of energy saving. 2. Increasing the operation efficiency of hot blast stove, to have operation technique more Sophisticated, in the meantime, to eradicate the moisture out of BFG/Air and further extend the life time of ceramic burner of hot blast stove. 3. The Waste Gas Heat Recovery System has been totally mature with good reference of operation in the world market, which has been used by most steel mills in the world. There is actually no risk to adopt and apply this technology, & further carve out the good image of company ¡§C¡¨ in the respect of energy saving. 4. Reduction of SOx out of waste gas, and further diminish the temperature of waste gas released and can reduce the CO2 emission that is friendly to our environment. The research of this study recognized further, that energy intensified industry has been built up due to the scenario and situation of Taiwan in past few decades, in view of the development of economy, which is crucial industry & business sector. However, with the time running, the energy intensified industry requires to be adjusted for adaptation to the industrial environment of energy crisis and global warming. In this case, the largest potential worry for Taiwan is obviously insufficiency of energy supply. Furthermore, the technical level of energy saving of Taiwan is far more behind Japan, & many other European countries. General Speaking, the energy intensified industry of Taiwan is in weak situation at this moment. If Taiwan might introduce more advanced technology, and technical cooperation, technical research and development, or even training of qualified personnel enabling to upgrade the energy saving of Taiwan to be further upgraded for increasing the competitiveness of industries which is surely positive for a nation being more competitive. In view of energy intensified industry, shortage of energy supply and the price be kept high end, the recycling energy is not available within short time, for short and mid term, the best effective measures to solve the problem of energy is to reduce the amount of energy, for long run, it is great help to use the energy saving system to the energy intensified industry. For one hand, it might reduce the production cost; on the other hand, it can increase the energy operation efficiency. The heat pipe Waste Gas Heat Recovery System as described in this Study is well sound technology of energy saving.

Thesis (M. Sc.)--University of Hong Kong, 1982.

No description available.

This work focuses on an innovative Rotary Displacer SE (RDSE) configuration for Stirling engines (SEs). RDSE features rotary displacers instead of reciprocating displacers (found in conventional SE configurations), as well as combined compression and expansion spaces. Guided by the research question "can RDSE as a novel configuration achieve a higher efficiency compared to conventional SE configurations at comparable operating conditions?", the goal of this study is to characterize, analyze, and optimize RDSE which is pursued in three technical stages. It is observed the RDSE prototype has an optimum phase angle of > 90° and thermal efficiency of 15.5% corresponding to 75.2% of the ideal (Carnot) efficiency at the source and sink temperatures of 98.6° C and 22.1° C, respectively. Initial results indicate that 125° phase angle provides more power than that of the theoretically optimum 90° phase angle. The results also show comparable B_n and significantly higher W_n values (0.047 and 0.465, respectively) compared to earlier studies, and suggest the RDSE could potentially be a competitive alternative to other SE configurations. Furthermore, due to lack of a regenerator, the non-ideal effects calculated in the analytical approach have insignificant impact (less than 0.03 kPa in 100 kPa). The clearance volume in the shuttled volume has a dramatic negative effect and reduces the performance up to 40%. Ultimately, utilizing CFD, it is proved that the existing geometry is relatively optimized where the optimum phase angle is 121° and geometric ratio D\/L for the displacer is 0.49.

Anaerobic digestion has great potential as an energy source. Not only does it provide an effective method for waste mitigation, but it has the potential to generate significant quantities of fuel and electricity. In order to ensure efficient digestion and biomass utilization, however, the system must be continuously maintained at elevated temperatures. It is technically feasible to supplement such a system with outside energy, but it is more cost effective to heat the system using only the produced biogas. While there is considerable literature covering the theory of anaerobic digestion, there are very few practical studies to show how heat utilization affects system operation. This study considers the effect of major design variables (i.e. heat exchanger efficiencies and biogas conditioning) on promoting a completely self-sustaining digestion system. The thesis considers a real world system and analyzes how it can be improved to avoid the need of an external energy source.