On the use of SAFT-VR Mie for assessing large-glide fluorocarbon working-fluid mixtures in organic Rankine cycles

Oyewunmi, Oyeniyi A.; Taleb, Aly I.; Haslam, Andrew J.; Markides, Christos N.

doi:10.1016/j.apenergy.2015.10.040

Cited by 81 publications

(32 citation statements)

References 48 publications

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“…The pure working fluids on the other hand will produce slightly less power but with the advantage of smaller sized process units and at considerably lower costs. Previous research efforts into the deployment of working-fluid mixtures (multi-component working fluids) in ORC systems [2][3][4][5][7][8][9][11][12][13]15,18,34,43] have generally considered the thermodynamic benefits of such mixtures in comparison with pure (single component) working fluids, and as exemplified earlier with the results in Section 3.1, the mixtures do give better performance (in terms of net power output and/or thermal/exergy efficiencies) than the pure fluids. These mixtures have, however, been shown to suffer a deterioration in their heat transfer performance especially during the phase-change processes.…”

Section: Multi-objective Cost-power Optimizationmentioning

confidence: 90%

“…In fact, the temperature glide is a reasonably good predictor of the maximum power-output in our study, since high power-output mixtures have relatively high temperature glides, which are also closer to the external heat sink temperature changes (10 • C). Although this holds true for closely related binary mixtures, it has been suggested that mixtures of highly dissimilar fluids may not follow this trend [5,18,34].…”

Section: Optimal Cycles With Working-fluid Mixturesmentioning

confidence: 99%

“…The selection of working fluids for ORC systems has received attention recently, including a particular interest in multi-component fluid mixtures, due to the opportunities they offer in improving thermodynamic performance. Various authors have performed investigations to demonstrate and quantify these benefits, which have shown that fluid mixtures and pure fluids at supercritical pressures can achieve an improved thermal match with the heat source (i.e., a reduced average temperature-difference) compared to the isothermal profile of the (isobaric, sub-critical) evaporation of pure-component fluids, thereby reducing exergy losses due to heat transfer, and increasing thermal and exergy efficiencies [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

Oyewunmi

Markides

2016

Energies

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Abstract:In the present paper, we consider the employment of working-fluid mixtures in organic Rankine cycle (ORC) systems with respect to thermodynamic and heat-transfer performance, component sizing and capital costs. The selected working-fluid mixtures promise reduced exergy losses due to their non-isothermal phase-change behaviour, and thus improved cycle efficiencies and power outputs over their respective pure-fluid components. A multi-objective cost-power optimization of a specific low-temperature ORC system (operating with geothermal water at 98 • C) reveals that the use of working-fluid-mixtures does indeed show a thermodynamic improvement over the pure-fluids. At the same time, heat transfer and cost analyses, however, suggest that it also requires larger evaporators, condensers and expanders; thus, the resulting ORC systems are also associated with higher costs. In particular, 50% n-pentane + 50% n-hexane and 60% R-245fa + 40% R-227ea mixtures lead to the thermodynamically optimal cycles, whereas pure n-pentane and pure R-245fa have lower plant costs, both estimated as having ∼14% lower costs per unit power output compared to the thermodynamically optimal mixtures. These conclusions highlight the importance of using system cost minimization as a design objective for ORC plants.

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Section: Multi-objective Cost-power Optimizationmentioning

confidence: 90%

Section: Optimal Cycles With Working-fluid Mixturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

Oyewunmi

Markides

2016

Energies

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“…Chys et al [15] showed that ORC with suitable binary mixture working fluid produces 20% more power output and increases thermal efficiency by 15% over ORC with pure working fluids. Oyewunmi et al [16] extended the range of mixture working fluids based on SAFT-VR Mie equation of state, which enables to predict mixture properties where experimental data are not available. In addition, economics of system can lead to different conclusions in fluid selection.…”

Section: Introductionmentioning

confidence: 99%

Performance characteristics of a 200-kW organic Rankine cycle system in a steel processing plant

et al. 2016

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“…ORC systems have the design option of employing a number of organic working fluids, ranging from refrigerants to hydrocarbons and siloxanes [22], including working fluid mixtures [23] in order to optimize the heat transfer (and heat recovery) from/to the waste heat source and heat sink [24]. The use of zeotropic mixtures is of particular interest as it can reduce thermodynamic irreversibility, e.g., in the condenser [25].…”

Section: Introductionmentioning

confidence: 99%

Case Study of an Organic Rankine Cycle (ORC) for Waste Heat Recovery from an Electric Arc Furnace (EAF)

et al. 2017

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The organic Rankine cycle (ORC) is a mature technology for the conversion of waste heat to electricity. Although many energy intensive industries could benefit significantly from the integration of ORC technology, its current adoption rate is limited. One important reason for this arises from the difficulty of prospective investors and end-users to recognize and, ultimately, realise the potential energy savings from such deployment. In recent years, electric arc furnaces (EAF) have been identified as particularly interesting candidates for the implementation of waste heat recovery projects. Therefore, in this work, the integration of an ORC system into a 100 MWe EAF is investigated. The effect of evaluations based on averaged heat profiles, a steam buffer and optimized ORC architectures is investigated. The results show that it is crucial to take into account the heat profile variations for the typical batch process of an EAF. An optimized subcritical ORC system is found capable of generating a net electrical output of 752 kWe with a steam buffer working at 25 bar. If combined heating is considered, the ORC system can be optimized to generate 521 kWe of electricity, while also delivering 4.52 MW of heat. Finally, an increased power output (by 26% with combined heating, and by 39% without combined heating) can be achieved by using high temperature thermal oil for buffering instead of a steam loop; however, the use of thermal oil in these applications has been until now typically discouraged due to flammability concerns.

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On the use of SAFT-VR Mie for assessing large-glide fluorocarbon working-fluid mixtures in organic Rankine cycles

Cited by 81 publications

References 48 publications

Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

Thermo-Economic and Heat Transfer Optimization of Working-Fluid Mixtures in a Low-Temperature Organic Rankine Cycle System

Performance characteristics of a 200-kW organic Rankine cycle system in a steel processing plant

Case Study of an Organic Rankine Cycle (ORC) for Waste Heat Recovery from an Electric Arc Furnace (EAF)

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