Novel classification of pure working fluids for Organic Rankine Cycle

Györke, Gábor; Deiters, Ulrich K.; Groniewsky, Axel; Lassu, Imre; Imre, Attila R.

doi:10.1016/j.energy.2017.12.135

Cited by 86 publications

(78 citation statements)

References 14 publications

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“…This point is located near the critical point and defined as the turning point. Its more detailed discussion can be found in paper [37]; other details about the role of this point can be seen elsewhere [38]. The turning point temperature is the limit of subcritical ORC which adopts turbo-type expander [37].…”

Section: Thermodynamic Setting and Descriptionmentioning

confidence: 99%

Zeotropic Mixture Selection for an Organic Rankine Cycle Using a Single Screw Expander

Zhang

et al. 2020

Energies

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The organic Rankine cycle (ORC) is a popular and promising technology that has been widely studied and adopted in renewable and sustainable energy utilization and low-grade waste heat recovery. The use of zeotropic mixtures in ORC has been attracting more and more attention because of the possibility to match the temperature profile of the heat source by non-isothermal phase change, which reduces the irreversibility in the evaporator and the condenser. The selection of working fluid and expander is strongly interconnected. As a novel expander, a single screw expander was selected and used in this paper for efficient utilization of the wet zeotropic mixtures listed in REFPROP 9.1 in a low-temperature subcritical ORC system. Five indicators, namely net work, thermal efficiency, heat exchange load of condenser, temperature glide in evaporator, and temperature glide in condenser, were used to analyze the performance of an ORC system with wet and isentropic zeotropic mixtures as working fluids. The calculation and analysis results indicate that R441A with an expander outlet temperature of 320 K may be the suitable zeotropic mixture used for both open and close type heat source. R436B may be selected with an expander outlet temperature of 315 K. R432A may be selected with an expander outlet temperature from 295 K to 310 K.

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Section: Thermodynamic Setting and Descriptionmentioning

confidence: 99%

Zeotropic Mixture Selection for an Organic Rankine Cycle Using a Single Screw Expander

Zhang

et al. 2020

Energies

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“…Also, there is a mainly theoretical issue relating to the dryness of the fluid. If the fluid is "very dry", it bends back greatly to lower entropies; however, at least underneath the critical point, it becomes possible to fully liquefy vapor using an isentropic compression and vice versa (to fully evaporate liquid using an isentropic expansion) [18].…”

Section: Deficiencies In Traditional Classificationmentioning

confidence: 99%

“…A novel classification method was developed by us [18] not only to describe and categorize all the potential working fluids, but also to use some elements of the classification as a tool for finding the best working fluid for a given heat source. A short review of the novel classification is given in Section 3.…”

Section: Introductionmentioning

confidence: 99%

“…Using one or two of these points and correlating them with the isochoric molar specific heat capacities of the equilibrium vapor phase, we are able to give a "rule of thumb" to select working fluids, where droplet formation during expansion and, hence, the potentially harmful droplet erosion of turbine blades-common for traditional and some organic Rankine processes using wet working fluids [19,20]-can be avoided. In this way, several new potential working fluids can be found and used for further evaluation, using general criteria for ORC working fluid selection including thermodynamics [18,21], safety and environmental impact [22,23], availability, compatibility, and cost-effectiveness [24], or most often, a combination of these criteria.…”

Section: Introductionmentioning

confidence: 99%

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

2019

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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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“…A performance evaluation is developed for R245fa and R600a since they are the most used working fluids in geothermal ORC power plants in the Molasse Basin [16,26,27]. Nevertheless, wet fluids [28] (such as R134a, without recuperator), isopentane and R227ea have also been tested, even though showing unfeasible results due to the very low reinjection temperature. This would lead to scaling in the heat exchangers and to an unfavourable management of the geothermal reservoir.…”

Section: New-build Systemmentioning

confidence: 99%

Techno-Economic Analysis of Hybrid Binary Cycles with Geothermal Energy and Biogas Waste Heat Recovery

2019

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In Germany, enhancing renewable power generation represents a leading step to comply with the requirements of the Energiewende agenda. The geothermal reservoir in Oberhaching is assumed as a case study, with a gross electric power equal to 4.3 MWel. The intent of this work is to design a hybrid binary geothermal power plant and to integrate it into the German energy market. Biogas waste thermal power equal to 1350 kWth is assumed as a secondary source. Two different layouts are defined for the hybrid solution: increasing the geothermal fluid temperature before entering the organic Rankine cycle (ORC) unit and superheating the working fluid after the evaporator. Stationary and quasi-stationary simulations have been performed with Aspen Plus V8.8. Results demonstrate how hybridization allows a maximum electric power increase of about 240 kWel. Off-design conditions are investigated regarding both the switch-off of exhaust gases and the annual ambient temperature fluctuations. In spite of the additional secondary source, the selected case studies cannot comply with the Minute reserve requirements (MRL). Moreover, economic results for both power-only and combined heat and power (CHP) configuration are provided. In the power-only configuration, the new-build hybrid system provides 15.42 €ct/kWh as levelized cost of electricity (LCOE), slightly lower than 16.4 €ct/kWh, as calculated in the geothermal-only solution. A CHP hybrid configuration shows a +19.22% increase in net cash flow at the end of the investment on the CHP geothermal solution.

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Novel classification of pure working fluids for Organic Rankine Cycle

Cited by 86 publications

References 14 publications

Zeotropic Mixture Selection for an Organic Rankine Cycle Using a Single Screw Expander

Zeotropic Mixture Selection for an Organic Rankine Cycle Using a Single Screw Expander

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

Techno-Economic Analysis of Hybrid Binary Cycles with Geothermal Energy and Biogas Waste Heat Recovery

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