Evaluation of isopentane, R-245fa and their mixtures as working fluids for organic Rankine cycles

Garg, Pardeep; Kumar, Pramod; Srinivasan, Kandadai; Dutta, Pradip

doi:10.1016/j.applthermaleng.2012.08.056

Cited by 108 publications

(40 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the context of geothermal applications, several case studies are performed for zeotropic mixtures as ORC working fluids considering subcritical and transcritical cycles [11][12][13]. More comprehensive analyses including sensitivity for crucial parameters, like mixture composition, heat source temperature or temperature difference of the cooling media are recently performed [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In general, results confirm the potential for an increase in efficiency of ORC systems by the use of zeotropic mixtures as working fluids.…”

Section: Introductionmentioning

confidence: 60%

Thermo-Economic Evaluation of Organic Rankine Cycles for Geothermal Power Generation Using Zeotropic Mixtures

Heberle

Brüggemann

2015

Energies

View full text Add to dashboard Cite

Abstract:We present a thermo-economic evaluation of binary power plants based on the Organic Rankine Cycle (ORC) for geothermal power generation. The focus of this study is to analyse if an efficiency increase by using zeotropic mixtures as working fluid overcompensates additional requirements regarding the major power plant components. The optimization approach is compared to systems with pure media. Based on process simulations, heat exchange equipment is designed and cost estimations are performed. For heat source temperatures between 100 and 180 °C selected zeotropic mixtures lead to an increase in second law efficiency of up to 20.6% compared to pure fluids. Especially for temperatures about 160 °C, mixtures like propane/isobutane, isobutane/isopentane, or R227ea/R245fa show lower electricity generation costs compared to the most efficient pure fluid. In case of a geothermal fluid temperature of 120 °C, R227ea and propane/isobutane are cost-efficient working fluids. The uncertainties regarding fluid properties of zeotropic mixtures, mainly affect the heat exchange surface. However, the influence on the determined economic parameter is marginal. In general, zeotropic mixtures are a promising approach to improve the economics of geothermal ORC systems. Additionally, the use of mixtures increases the spectrum of potential working fluids, which is important in context of present and future legal requirements considering fluorinated refrigerants.

show abstract

Section: Introductionmentioning

confidence: 60%

Thermo-Economic Evaluation of Organic Rankine Cycles for Geothermal Power Generation Using Zeotropic Mixtures

Heberle

Brüggemann

2015

Energies

View full text Add to dashboard Cite

show abstract

“…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%

“…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%

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

Oyewunmi

Markides

2016

Energies

View full text Add to dashboard Cite

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.

show abstract

“…Recently many other studies showed the selection of working fluids was very important for the ORC system performance, see for example Bao and Zhao (2014), Cho et al (2014) or Garg et al (2013). Rayegan et al (2011) who developed a procedure to compare the thermodynamic properties of working fluids under similar working conditions.…”

Section: Selection Of Appropriate Working Fluid For Orc Installationmentioning

confidence: 99%

Criteria for selection of working fluid in low-temperature ORC

Mikielewicz¹,

Mikielewicz²

2016

Chemical and Process Engineering

View full text Add to dashboard Cite

The economics of an ORC system is strictly linked to thermodynamic properties of the working fluid. A bad choice of working fluid could lead to a less efficient and expensive plant/generation unit. Some selection criteria have been put forward by various authors, incorporating thermodynamic properties, provided in literature but these do not have a general character. In the paper a simple analysis has been carried out which resulted in development of thermodynamic criteria for selection of an appropriate working fluid for subcritical and supercritical cycles. The postulated criteria are expressed in terms of non-dimensional numbers, which are characteristic for different fluids. The efficiency of the cycle is in a close relation to these numbers. The criteria are suitable for initial fluid selection. Such criteria should be used with other ones related to environmental impact, economy, system size, etc. Examples of such criteria have been also presented which may be helpful in rating of heat exchangers, which takes into account both heat transfer and flow resistance of the working fluid.

show abstract

Evaluation of isopentane, R-245fa and their mixtures as working fluids for organic Rankine cycles

Cited by 108 publications

References 19 publications

Thermo-Economic Evaluation of Organic Rankine Cycles for Geothermal Power Generation Using Zeotropic Mixtures

Thermo-Economic Evaluation of Organic Rankine Cycles for Geothermal Power Generation Using Zeotropic Mixtures

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

Criteria for selection of working fluid in low-temperature ORC

Contact Info

Product

Resources

About