15:40
System design and optimization VI
Chair: Prof. Brian Elmegaard
15:40
20 mins
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TECHNICAL CONSIDERATIONS OF CHARGE AIR HEAT UTILIZATION OF LARGE DIESEL ENGINES BY MEANS OF ORC
Antti Uusitalo, Juha Honkatukia, Sami Nyyssönen, Teemu Turunen-Saaresti
Abstract: Modern large-scale reciprocating engines can achieve high electrical efficiencies of up to 47 %. Despite the high efficiency of modern engine power plants, a large amount of energy is wasted in the process in a form of heat. The most significant heat streams in large diesel engine power plants can be identified as high-temperature exhaust gas heat and lower temperature heat streams from the charge air cooler, as well as jacket water and lube oil heat. The most significant efficiency improvement is related to exhaust gas heat, which is mainly utilized by using conventional steam Rankine cycles or high-temperature ORC. In addition, significant amounts of heat could be recovered also from the lower temperature heat streams to boost the electric power output of the system.
Modern large-scale reciprocating engines are characterized by high pressure ratio turbochargers. In single-stage compression in a turbocharger compressor, the charge air temperature increases typically to 180-220 oC. This heat could be utilized in additional electricity production by replacing the engine intercooler with an ORC process.
This study presents and discusses the technical aspects of designing ORC systems for charge air heat utilization. Different ORC working fluids were compared by evaluating thermodynamic performance of the ORC by means of process simulations. An experimental setup is designed to investigate the performance of this type of engine combined cycle with different ORC working fluids. The experimental results are expected to be available at the end of year 2013.
REFERENCES
[1] Z.Q. Wang, N.J. Zhou, J. Guo, X.Y. Wang, “Fluid selection and parametric optimization of organic Rankine cycle using low temperature waste heat” Energy, Vol 40, pp. 107-115, (2012).
[2] J. Larjola, "Electricity from Industrial Waste Heat Using High-Speed Organic Rankine Cycle (ORC)", Int. J. Production Economics, Vol. 41 pp. 227-235, (1995).
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16:00
20 mins
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THERMO-ECONOMIC OPTIMIZATION OF SUBCRITICAL AND TRANSCRITICAL ORC SYSTEMS
Thomas Tartière, Benoit Obert, Laurent Sanchez
Abstract: Recent studies underline the great potential of using trans-critical Organic Rankine Cycles (ORC) in order to increase the thermal efficiency of electricity production from low-temperature heat sources. However, the choice of a supercritical high pressure in the system has significant consequences on the costs and performances of its subcomponents. This work develops a method intended for assessing the thermo-economic potential of trans-critical cycles for various fluids and heat source temperatures in the range 80-150°C. Effects on heat exchanger areas are analyzed using plate heat exchanger models. Axial turbine preliminary design is carried out. Then, cost functions are built for every components of the system, leading to an estimation of the specific investment cost (SIC). Multi-parameters optimization is carried out for heat source temperatures between 80°C and 150°C, with SIC as objective function. Results are described and analyzed for different fluids, showing that the choice of a supercritical high pressure does not necessarily lead to an economic optimum.
REFERENCES
[1] S. Quoilin, S. Declaye, B. Tchanche, V. Lemort, “Thermo-economic optimization of waste heat recovery Organic Rankine Cycles”, Applied Thermal Engineering, Vol. 31, pp. 2885-2893, (2011)
[2] S. Zhang, H. Wang, G. Tao, “Performance comparison and parametric optimization of subcritical Organic Rankine Cycle (ORC) and transcritical power cycle system for low-temperature geothermal power generation”, Applied Energy, Vol. 88, pp. 2740-2754, (2011)
[3] G. Tao, H. Wang, S. Zhang, “Comparative analysis of natural and conventional working fluids for use in transcritical Rankine cyle using low temperature geothermal source”, International Journal of Energy Research, Vol. 35, pp. 530-544, (2011)
[4] S. Karellas, A. Schuster, A.D. Leontaritis, “Influence of supercritical ORC parameters on plate heat exchanger design”, Applied Thermal Engineering, Vol. 33-34, pp. 70-76, (2012)
ACKNOWLEDGMENT
The investigations presented in the paper have been partially funded by the French Environment and Energy Management Agency (ADEME).
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16:20
20 mins
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CONCEPT OF THE GEO-BIO MICRO POWER PLANT
Dorota Piotrowska, Wladyslaw Kryllowicz, Lukas Antczak
Abstract: This paper presents a concept and a test stand of the hybrid micro power plant. The plant has been referred to as geo-bio and is of a binary type in the thermodynamic sense. The system consists of two cycles: an upper steam cycle using energy from the combustion of biomass and a geothermal energy assisted bottom cycle - an ORC (Organic Rankine Cycle) using waste heat from the upper cycle. The micro power plant is composed of two turbines - a steam turbine of the upper cycle and an ORC turbine of the bottom cycle. A single Curtis stage (in the radial arrangement) is used as the steam turbine. The ORC turbine is made as a hermetic turboset unit. Heat exchangers are of a plate type. The experimental results show a technical applicability of the concept.
The paper presents some technical details and selected results of the tests.
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16:40
20 mins
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NANO ORGANIC RANKINE CYCLE FOR ENHANCED HEAT RECOVERY
Bahram Saadatfar, Reza Fakhrai, Torsten Franson
Abstract: There will be an incredible energy challenge in the future. With growing population, more and more energy needs to meet society’s demands. Fossil fuels are limited resources; hence there will be need more renewable energy as well as more efficient use of energy by recovering low-grade heat source.
An organic Rankine cycle (ORC) system would be attractive and promising technology for energy conversion systems in low temperature thermal energy sources. Many actual ORC’s applications have been installed; nevertheless, one of the major challenges in the ORC technology is working fluid. The difficulties involved in the accurate thermophysical properties in addition to safety of organic fluids that are commonly found in ORC, may result in relatively low efficiency as well as heat exchanger and component size.
In the organic Rankine cycle, heat exchangers, including evaporators and condensers, are the dominant components with most working fluid accumulation. Moreover, the working fluid is linked to the expansion part; therefore, selecting an organic fluid and expander should be performed at the same time.
Conventional Organic Rankine Cycle uses organic fluid as a working fluid, whereas nano fluid organic Rankine cycle (nORC) uses nano material and organic compound as a working fluid and it is particularly suitable for utilizing small scale heat exchangers, due to creating better thermal match both in boiling and condensing, in low temperature applications.
In this work, utilizing nano organic fluid as a working fluid for ORC for Some types of nanoparticles are studied; thermophysical properties of nano ORC candidate in the specific temperature range are measured and analyzed. Also, this study presents acceptable operating conditions and expansion machine by investigating the interaction among the expansion part and nano organic working fluid.
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