A new selection principle of working fluids for subcritical organic Rankine cycle coupling with different heat sources

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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Second Law Analysis and Optimization of Organic Rankine Cycle

ASME 2006 Power Conference ◽

10.1115/power2006-88061 ◽

2006 ◽

Cited By ~ 17

Author(s):

C. Somayaji ◽

P. J. Mago ◽

L. M. Chamra

Keyword(s):

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Operating Conditions ◽

Working Fluid ◽

Second Law ◽

Low Grade ◽

Heat Sources ◽

Working Fluids ◽

Second Law Analysis

This paper presents a second law analysis and optimization for the use of Organic Rankine Cycle “ORC” to convert waste energy to power from low grade heat sources. The working fluids used in this study are organic substances which have a low boiling point and a low latent heat for using low grade waste heat sources. The organic working fluids under investigation are R134a and R113 and their results are compared with those of ammonia and water under similar operating conditions. A combined first and second law analysis is performed by varying some system operating parameters at various reference temperatures. Some of the results show that the efficiency of ORC is typically below 20% depending on the temperatures and matched working fluid. In addition, it has been found that organic working fluids are more suited for heat recovery than water for low temperature applications, which justifies the use of organic working fluids at the lower waste source temperatures.

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Organic Rankine-Cycle Turbine Power Plant Utilizing Low Temperature Heat Sources

Volume 1B: General ◽

10.1115/80-gt-153 ◽

1980 ◽

Author(s):

V. Maizza

Keyword(s):

Power Plant ◽

Low Temperature ◽

High Efficiency ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Heat Sources ◽

Operational Parameters ◽

Working Fluids ◽

Waste Energy

Utilizing and converting of existing low temperature and waste heat sources by the use of a high efficiency bottoming cycle is attractive and should be possible for many locations. This paper presents a theoretical study on possible combination of an organic Rankine-cycle turbine power plant with the heat pump supplied by waste energy sources. Energy requirements and system performances are analyzed using realistic design operating condition for a middle town. Some conversion systems employing working fluids other than water are being studied for the purpose of proposed application. Thermodynamic efficiencies, with respect to available resource, have been calculated by varying some system operating parameters at various reference temperature. With reference to proposed application equations and graphs are presented which interrelate the turbine operational parameters for some possible working fluids with computation results.

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Selecting working fluids in an organic Rankine cycle for power generation from low temperature heat sources

DYNA ◽

10.15446/dyna.v81n188.41666 ◽

2014 ◽

Vol 81 (188) ◽

pp. 173-180 ◽

Cited By ~ 1

Author(s):

Fredy Vélez

Keyword(s):

Power Generation ◽

Low Temperature ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Heat Sources ◽

Working Fluids ◽

Temperature Heat

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PERFORMANCE ANALYSIS OF WORKING FLUIDS ON ORGANIC RANKIE CYCLE (ORC) MODEL WITH BIOMASS ENERGY AS A HEAT SOURCES

Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) ◽

10.23960/jtep-l.v8i3.175-186 ◽

2019 ◽

Vol 8 (3) ◽

pp. 175

Author(s):

Lilis Sucahyo

Keyword(s):

Performance Analysis ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Biomass Energy ◽

Working Fluid ◽

Inlet Temperature ◽

Heat Sources ◽

Working Fluids ◽

Fluid Properties ◽

And Performance

Organic Rankine Cycle (ORC) is an electricity power technology particularly suitable for medium-low temperature heat sources and/or for small available termal power. This paper presents the simulation and performance analysis of working fluids R-134a, R-414B, R-404A and R-407C on ORC with biomass energy as a heat source. Simulation of the ORC system using Cycle Tempo software. The property of working fluids is obtained by using Reference Fluid Properties (Refprop). The best result performance of ORC was shown by working fluid R-404A with thermal efficiency 7.54 % and electric power output ranges between 0.075 kW. This condition operated on turbine inlet temperature at 60 oC, difference turbine working temperature of 15 oC, condensing temperature 25 oC and water boiler mass flow rate 3 lpm.

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Selection of Working Fluids for Low-Temperature Power Generation Organic Rankine Cycles System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.557-559.1509 ◽

2012 ◽

Vol 557-559 ◽

pp. 1509-1513 ◽

Cited By ~ 2

Author(s):

Zhong He Han ◽

Yi Da Yu

Keyword(s):

Low Temperature ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Heat Sources ◽

Working Fluids ◽

Cycle System ◽

Organic Rankine Cycles ◽

Organic Fluids ◽

Cycle Efficiency

A Rankine cycle using organic fluids as working fluids, called organic Rankine cycle (ORC), is potentially feasible in recovering low enthalpy containing heat sources. The choices of fluids should meet the requirement of environment, safety, critical pressure and critical temperature etc. Under the proposed working conditions, R600a, R245fa, R236fa, R236ea, R227ea are chosen as the working fluids of the low-temperature Rankine cycle system, then those fluids are investigated and compared from cycle efficiency, work ratio, exergy efficiency, irreversible loss. The results show that R245fa is an available and effective working fluid for low-temperature Rankine cycle.

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