MODELING OF AN ORGANIC RANKINE CYCLE FOR LOW TEMPERATURE HEAT SOURCES

Abstract Even though the renewable technologies are getting a gradually increasing share of the energy industry, the momentum of its growth is far away from outweighing the dominance of fossil fuel. Due to the concern for ozone depletion, global warming, and many more environmental hazards caused by fossil fuels, it is essential to substitute the conventional energy sources with renewables. Since this replacement cannot be done overnight, the conventional energy technologies should be integrated with renewables to minimize the pace of adverse effects on fossil fuel–based industries in the meantime. This way, the industries can be more efficient by utilizing waste heat, which accounts for 50% of the total energy generated now. This review paper outlines the role of solar energy in the generation of power and cooling systems that are capable of utilizing low-temperature heat sources below 400 °C. The review is primarily concentrated on line-focused concentrated solar power (CSP)-assisted solar technologies to be integrated with organic Rankine cycle (ORC) and absorption cooling systems. Photovoltaic and similar multigeneration systems are also discussed in brief.

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Optimization of Cycle and Expander Design of an Organic Rankine Cycle Unit Using Multi-Component Working Fluids

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems ◽

10.1115/gt2016-58065 ◽

2016 ◽

Cited By ~ 1

Author(s):

Andrea Meroni ◽

Jesper Graa Andreasen ◽

Leonardo Pierobon ◽

Fredrik Haglind

Keyword(s):

Low Temperature ◽

Power Systems ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Fluid Temperature ◽

Heat Sources ◽

Working Fluids ◽

Turbine Performance ◽

Temperature Heat

Organic Rankine cycle (ORC) power systems represent attractive solutions for power conversion from low temperature heat sources, and the use of these power systems is gaining increasing attention in the marine industry. This paper proposes the combined optimal design of cycle and expander for an organic Rankine cycle unit utilizing waste heat from low temperature heat sources. The study addresses a case where the minimum temperature of the heat source is constrained and a case where no constraint is imposed. The former case is the waste heat recovery from jacket cooling water of a marine diesel engine onboard a large ship, and the latter is representative of a low-temperature geothermal, solar or waste heat recovery application. Multi-component working fluids are investigated, as they allow improving the match between the temperature profiles in the heat exchangers and, consequently, reducing the irreversibility in the ORC system. This work considers mixtures of R245fa/pentane and propane/isobutane. The use of multi-component working fluids typically results in increased heat transfer areas and different expander designs compared to pure fluids. In order to properly account for turbine performance and design constraints in the cycle calculation, the thermodynamic cycle and the turbine are optimized simultaneously in the molar composition range of each mixture. Such novel optimization approach enables one to identify to which extent the cycle or the turbine behaviour influences the selection of the optimal solution. It also enables one to find the composition for which an optimal compromise between cycle and turbine performance is achieved. The optimal ORC unit employs pure R245fa and provides approximately 200 kW when the minimum hot fluid temperature is constrained. Conversely, the mixture R245fa/pentane (0.5/0.5) is selected and provides approximately 444 kW when the hot fluid temperature is not constrained to a lower value. In both cases, a compact and efficient turbine can be manufactured.

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A Simple Method of Finding New Dry and Isentropic Working Fluids for Organic Rankine Cycle

Energies ◽

10.3390/en12030480 ◽

2019 ◽

Vol 12 (3) ◽

pp. 480 ◽

Cited By ~ 9

Author(s):

Gábor Györke ◽

Axel Groniewsky ◽

Attila Imre

Keyword(s):

Low Temperature ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Electricity Production ◽

Working Fluid ◽

Heat Sources ◽

Simple Method ◽

Working Fluids ◽

Temperature Heat

One of the most crucial challenges of sustainable development is the use of low-temperature heat sources (60–200 °C), such as thermal solar, geothermal, biomass, or waste heat, for electricity production. Since conventional water-based thermodynamic cycles are not suitable in this temperature range or at least operate with very low efficiency, other working fluids need to be applied. Organic Rankine Cycle (ORC) uses organic working fluids, which results in higher thermal efficiency for low-temperature heat sources. Traditionally, new working fluids are found using a trial-and-error procedure through experience among chemically similar materials. This approach, however, carries a high risk of excluding the ideal working fluid. Therefore, a new method and a simple rule of thumb—based on a correlation related to molar isochoric specific heat capacity of saturated vapor states—were developed. With the application of this thumb rule, novel isentropic and dry working fluids can be found applicable for given low-temperature heat sources. Additionally, the importance of molar quantities—usually ignored by energy engineers—was demonstrated.

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Analysis of a Combined Power and Ejector Refrigeration Cycle for Low Temperature Heat Sources

ASME 2009 3rd International Conference on Energy Sustainability, Volume 2 ◽

10.1115/es2009-90047 ◽

2009 ◽

Author(s):

Bin Zheng ◽

Yiwu Weng

Keyword(s):

Low Temperature ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Combined Cycle ◽

Refrigeration Cycle ◽

Heat Sources ◽

Working Fluids ◽

Temperature Heat ◽

Cycle Efficiency

This paper presents a combined power and ejector refrigeration cycle for low temperature heat sources. The proposed cycle combines the organic Rankine cycle and the ejector refrigeration cycle. It can be used as an independent cycle powered by the low temperature sources, such as solar energy, geothermal energy, or as a bottom cycle of the conventional power plant for the recovery of low temperature waste heat. A program was developed to calculate the performance of the combined cycle. Several substances were selected as the working fluids including R113, R123, R245fa, R141b and R600. Simulation results show that R141b has the highest cycle efficiency, followed by R123, R113, R600 and then R245fa. While the working fluids are calculated by per unit, R600 can produce more power and refrigeration outputs due to the large latent heat. Simulations at different generating temperatures, evaporating temperatures and condensing temperatures were also discussed.

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The Performance of the Kalina Cycle System 11(KCS-11) With Low-Temperature Heat Sources

Journal of Energy Resources Technology ◽

10.1115/1.2748815 ◽

2007 ◽

Vol 129 (3) ◽

pp. 243-247 ◽

Cited By ~ 89

Author(s):

H. D. Madhawa Hettiarachchi ◽

Mihajlo Golubovic ◽

William M. Worek ◽

Yasuyuki Ikegami

Keyword(s):

Low Temperature ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Inlet Pressure ◽

Cycle Performance ◽

Heat Sources ◽

Kalina Cycle ◽

Cycle System ◽

Temperature Heat ◽

Cycle Efficiency

The possibility of exploiting low-temperature heat sources has been of great significance with ever increasing energy demand. Optimum and cost-effective design of the power cycles provide a means of utilization of low-temperature heat sources which might otherwise be discarded. In this analysis, the performance of the Kalina cycle system 11 (KCS11) is examined for low-temperature geothermal heat sources and is compared with an organic Rankine cycle. The effect of the ammonia fraction and turbine inlet pressure on the cycle performance is investigated in detail. Results show that for a given turbine inlet pressure, an optimum ammonia fraction can be found that yields the maximum cycle efficiency. Further, the maximum cycle efficiency does not necessarily yield the optimum operating conditions for the system. In addition, it is important to consider the utilization of the various circulating media (i.e., working fluid, cooling water, and heat resource) and heat exchanger area per unit power produced. For given conditions, an optimum range of operating pressure and ammonia fraction can be identified that result in optimum cycle performance. In general, the KCS11 has better overall performance at moderate pressures than that of the organic Rankine cycle.

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Analysis of Radial Turbine of ORC Power Generation System for Low Temperature Heat Sources

ASME 2015 Power Conference ◽

10.1115/power2015-49165 ◽

2015 ◽

Cited By ~ 1

Author(s):

Zemin Bo ◽

Zhenkun Sang ◽

Qianqian Zhang ◽

Yiwu Weng

Keyword(s):

Power Generation ◽

Low Temperature ◽

Organic Rankine Cycle ◽

Leading Edge ◽

Rankine Cycle ◽

Heat Sources ◽

Generation System ◽

Radial Turbine ◽

Temperature Heat ◽

Power Generation System

The radial turbine is a key component of the Organic Rankine Cycle (ORC) power generation system. In order to improve the performance of ORC system for low temperature heat sources, a 150kW radial turbine using R600a has been designed and analyzed. First, the aerodynamic calculation of the radial turbine was conducted and one-dimensional aerodynamic parameters were obtained. Then three-dimensional CFD numerical analysis has been conducted to optimize the geometric design of the radial turbine. The results show the distribution of the flow field around the blades at different height and streamline distribution from leading edge to the trailing edge. At last, the effect of rotation speed on the performance of radial turbine was analyzed. The results can provide basic data for the design of radial turbine of ORC power generation system for low temperature heat sources.

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