Design, construction and commissioning of an organic Rankine cycle waste heat recovery system with a Tesla-hybrid turbine expander

2011 Fall.Includes bibliographical references.Issues surrounding energy are some of the most compelling subjects in the world today. With human's ever increasing need for energy, production must increase or consumption must be reduced to avoid an unsustainable long-term energy balance. One part of the energy solution is low-temperature Organic Rankine Cycles (ORCs). ORCs can be utilized to produce power in mass quantity from a dedicated heat source such as a geothermal well. ORCs may also be utilized as a waste heat recovery system to generate power from a heat stream that is typically rejected to the environment. Low-temperature waste heat streams are ubiquitous as every internal combustion engine generates 55-75% of its total fuel energy as waste heat. Efficiency of a waste heat recovery ORC system is strongly dependent on condensing temperature and expander efficiency. Condensing temperatures are typically kept low with an evaporative condensing unit. However, water consumption to increase energy production is becoming less tolerated. To provide a means to conduct research around these issues, a waste heat recovery ORC test bed was designed and constructed. This thesis contains information on construction and operation of the test bed with these features: R245fa working fluid, direct dry cooled condensing and a Tesla-hybrid turbine expander

Analysis of hot spots in boilers of organic Rankine cycle units during transient operation

none5siThis paper is devoted to the investigation of critical dynamic events causing thermochemical decomposition of the working fluid in organic Rankine cycle power systems. The case study is the plant of an oil and gas platform where one of the three gas turbines is combined with an organic Rankine cycle unit to increase the overall energy conversion efficiency. The dynamic model of the plant is coupled with a one-dimensional model of the once-through boiler fed by the exhaust thermal power of the gas turbine. The heat exchanger model uses a distributed cross-flow physical topology and local correlations for single- and two-phase heat transfer coefficients. The results indicate that severe load changes (0.4–1.0 MW s−1) can lead to exceedance of the temperature limit of fluid decomposition for a period of 10 min. Ramp rates lower than 0.3 MW s−1 are acceptable considering the stability of the electric grid and fluid decomposition. It is demonstrated that the use of a spray attemperator can mitigate the problems of local overheating of the organic compound. As a practical consequence, this paper provides guidelines for safe and reliable operation of organic Rankine cycle power modules on offshore installations.noneA. Benato;M.R. Kærn;L. Pierobon;A. Stoppato;F. HaglindBenato, Alberto; M. R., Kærn; L., Pierobon; Stoppato, Anna; F., Haglin

Technoecomonic optimization and working fluid selection for an engine coolant driven turbo-compression cooling system

2018 Summer.Includes bibliographical references.The abundance of low grade waste heat presents an opportunity to recover typically unused heat energy and improve system efficiencies in a number of different applications. This work examines the technoeconomic performance of a turbo-compression cooling system designed to recover ultra-low grade (≤ 100°C) waste heat from engine coolant in large marine diesel engine-generator sets. In addition, five different working fluids (R134a, R152a, R245fa, R1234ze(E), and R600a) were studied for this application to better understand the effects of fluid properties on technical and economic system performance. A coupled thermodynamic, heat exchanger, and economic model was developed to calculate the payback period of the turbo-compression cooling system. Then, the payback period was minimized by optimizing the surface area of the heat exchangers by varying the effectiveness of the heat exchangers. The sensitivity of the payback period to the heat exchanger effectiveness values was quantified to inform future design considerations. The turbo-compression cooling system with R152a had the lowest payback period of 1.67 years and an initial investment of $181,846. The R1234ze(E) system had the highest cooling capacity of 837 kW and the highest overall COP of 0.415. The R152a system provided cooling for$0.0060 per kWh which was nearly 10 times cheaper than the cost of cooling provided by a traditional electrically driven vapor compression system onboard a marine vessel

Reducing carbon footprint of deep-sea oil and gas field exploitation by optimization for Floating Production Storage and Offloading

Deep-sea oil and gas fields are acting as a vital role by providing substantial oil and gas resource, and Floating Production Storage and Offloading is an indispensable tool for the development of offshore oil and gas fields effectively. Here, Life Cycle Assessment is applied to evaluate environmental loads in the whole life cycle of the deep-sea oil and gas production. This paper explores the carbon footprint of Floating Production Storage and Offloading as the time axis. It is found that Floating Production Storage and Offloading is a conceptual product at the design stage and does not generate carbon emission, while the operational stage releases considerable emission by the fuel combustion process, accounting for 88.2% of the entire life cycle. To decrease this part of carbon emission, distributed energy system is considered as a promising choice because it integrates different energy resources and provides an economic and environmental energy allocation scheme to meet the energy demand. For the operation stage, this paper establishes a Multi-objective Mathematical Programming model to determine the selection and capacity of facilities with minimum annual total cost and carbon emissions by considering the energy balance and technical constraints. The model is validated by an example and solved by the weight method. According to designer's demand, distributed energy system can optimize economic objectives in a maximum range of 14.6%, and a maximum emission reduction of 4.53% can be expected compared with the traditional scheme. Sensitivity analysis shows that cost is more sensitive to natural gas price

ECOS 2012

The 8-volume set contains the Proceedings of the 25th ECOS 2012 International Conference, Perugia, Italy, June 26th to June 29th, 2012. ECOS is an acronym for Efficiency, Cost, Optimization and Simulation (of energy conversion systems and processes), summarizing the topics covered in ECOS: Thermodynamics, Heat and Mass Transfer, Exergy and Second Law Analysis, Process Integration and Heat Exchanger Networks, Fluid Dynamics and Power Plant Components, Fuel Cells, Simulation of Energy Conversion Systems, Renewable Energies, Thermo-Economic Analysis and Optimisation, Combustion, Chemical Reactors, Carbon Capture and Sequestration, Building/Urban/Complex Energy Systems, Water Desalination and Use of Water Resources, Energy Systems- Environmental and Sustainability Issues, System Operation/ Control/Diagnosis and Prognosis, Industrial Ecology

Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system

This paper presents an exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system. Based on the operating parameters obtained in system exploitation, it is performed analysis of each system component individually, as well as analysis of the whole observed system. While observing all heat exchangers it is found that combustion gases-CO2 heat exchangers have the lowest exergy destructions and the highest exergy efficiencies (higher than 92%). The lowest exergy efficiency of all heat exchangers is detected in Cooler (51.84%). Observed system is composed of two gas turbines and two compressors. The analysis allows detection of dominant mechanical power producer and the dominant mechanical power consumer. It is also found that the turbines from the observed system have much higher exergy efficiencies in comparison to compressors (exergy efficiency of both turbines is higher than 94%, while exergy efficiency of both compressors did not exceed 87%). The whole observed waste heat recovery system has exergy destruction equal to 6270.73 kW, while the exergy efficiency of the whole system is equal to 64.12% at the selected ambient state. Useful mechanical power produced by the whole system and used for electrical generator drive equals 11204.80 kW. The obtained high exergy efficiency of the whole observed system proves its application on-board ships

Energy: A continuing bibliography with indexes, issue 19

A bibliographical list of 1339 reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1978 through September 30, 1978 are presented

Techno-Economic Assessment of Waste Heat Recovery Technologies for the Food Processing Industry

The food manufacturing sector is one of the most dominant consumers of energy across the globe. Food processing methods such as drying, baking, frying, malting, roasting, etc. rely heavily on the heat released from burning fossil fuels, mainly natural gas or propane. Less than half of this heat contributes to the actual processing of the product and the remaining is released to the surroundings as waste heat, primarily through exhaust gases at 150 to 250 °C. Recovering this waste heat can deliver significant fuel, cost and CO2 savings. However, selecting an appropriate sink for this waste heat is challenging due to the relatively low source temperature. This study investigates a novel application of gas-to-air low temperature waste heat recovery technology for a confectionary manufacturing process, through a range of experiments. The recovered heat is used to preheat a baking oven’s combustion air at inlet before it enters the fuel-air mixture. The investigated technology is compared with other waste heat recovery schemes involving Regenerative Organic Rankine Cycles (RORC), Vapour Absorption Refrigeration (VAR) and hot water production. The findings indicate that utilising an oven’s exhaust gases to preheat combustion air can deliver up to 33% fuel savings, provided a sufficiently large heat sink in the form of oven combustion air is available. Due to a lower investment cost, the technology also offers a payback period of only 1.57 years, which makes it financially attractive when compared to others. The studied waste heat recovery technologies can deliver a CO2 savings of 28−356 tonnes per year from a single manufacturing site. The modelling and comparison methodology, observations and outcomes of this study can be extended to a variety of low temperature food manufacturing processes