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

Heberle, Florian; Brüggemann, Dieter

doi:10.3390/en8032097

Cited by 79 publications

(50 citation statements)

References 65 publications

(81 reference statements)

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“…Recent studies considered thermo-economic aspects in the performance evaluation of ORC systems [6][7][8][9][10][11][12][13][14][15]. Heberle and Brüggemann [6] carried out a thermodynamic optimization of zeotropic mixtures and pure fluids followed by an economic post-processing of the most promising mixtures and their pure fluids for heat source temperatures at 120 • C and 160 • C. The results indicated that the specific investment costs were higher for the mixtures.…”

Section: Introductionmentioning

confidence: 99%

Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

et al. 2016

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For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermal phase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cycle power plants enables a minimization of the mean temperature difference of the heat exchangers, which is beneficial for cycle performance. On the other hand, larger heat transfer surface areas are typically required for evaporation and condensation when zeotropic mixtures are used as working fluids. In order to assess the feasibility of using zeotropic mixtures, it is, therefore, important to consider the additional costs of the heat exchangers. In this study, we aim at evaluating the economic feasibility of zeotropic mixtures compared to pure fluids. We carry out a multi-objective optimization of the net power output and the component costs for organic Rankine cycle power plants using low-temperature heat at 90 • C to produce electrical power at around 500 kW. The primary outcomes of the study are Pareto fronts, illustrating the power/cost relations for R32, R134a and R32/R134a (0.65/0.35 mole ). The results indicate that R32/R134a is the best of these fluids, with 3.4 % higher net power than R32 at the same total cost of 1200 k$.

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Section: Introductionmentioning

confidence: 99%

Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

et al. 2016

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“…No exact specific investment costs numbers are presented, but the impact of various factors, such as brine inlet and outlet temperatures, pressure levels, electricity prices, discount rates and electricity price evolutions, on the economics of the ORC project are demonstrated. Heberle and Brüggemann [34] perform a thermo-economic evaluation of various zeotropic mixtures for geothermal ORC systems, with SICs between 3076 and 4882 € 2014 /kW. Other studies could not be included in Figure 1 because the economic values are expressed in €/kWh rather that €/kW, such as in Meinel et al [74] who perform a considerate comparison of architecture designs at various sizes.…”

Section: Orc Investment Costs: a Brief Literature Reviewmentioning

confidence: 99%

“…Also for ORC research cost estimation this technique is more often used: the total investment costs are estimated using the estimated purchased equipment costs. Some multiply the purchased equipment costs by a factor of 6.32 to obtain the total investment costs (e.g., [33][34][35]), as suggested by Bejan et al [14]. Note that this 6.32 multiplication factor is suggested for the erection of new systems; for expansion of existing systems a factor of 4.16 is proposed [14].…”

Section: Estimating the Total Investment Costs: Multiplication Factorsmentioning

confidence: 99%

“…Others estimate the costs through extrapolation from known costs of components or other ORC systems or via professional cost estimators (e.g., [30,31]). An increasing amount of researchers estimate the costs of components based on equipment correlations, using either percentages ( [32]) or multiplication factors ( [33][34][35]) to estimate the total project costs based on the module/equipment costs. Techno-economic ( [22,[36][37][38][39][40][41]) as well as thermo-or exergoeconomic ( [33,[42][43][44]) methods are used to simultaneously analyze technical and economic aspects and tradeoffs.…”

Section: Orc Investment Costs: a Brief Literature Reviewmentioning

confidence: 99%

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Cost Engineering Techniques and Their Applicability for Cost Estimation of Organic Rankine Cycle Systems

Lemmens

2016

Energies

113

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Abstract:The potential of organic Rankine cycle (ORC) systems is acknowledged by both considerable research and development efforts and an increasing number of applications. Most research aims at improving ORC systems through technical performance optimization of various cycle architectures and working fluids. The assessment and optimization of technical feasibility is at the core of ORC development. Nonetheless, economic feasibility is often decisive when it comes down to considering practical instalments, and therefore an increasing number of publications include an estimate of the costs of the designed ORC system. Various methods are used to estimate ORC costs but the resulting values are rarely discussed with respect to accuracy and validity. The aim of this paper is to provide insight into the methods used to estimate these costs and open the discussion about the interpretation of these results. A review of cost engineering practices shows there has been a long tradition of industrial cost estimation. Several techniques have been developed, but the expected accuracy range of the best techniques used in research varies between 10% and 30%. The quality of the estimates could be improved by establishing up-to-date correlations for the ORC industry in particular. Secondly, the rapidly growing ORC cost literature is briefly reviewed. A graph summarizing the estimated ORC investment costs displays a pattern of decreasing costs for increasing power output. Knowledge on the actual costs of real ORC modules and projects remains scarce. Finally, the investment costs of a known heat recovery ORC system are discussed and the methodologies and accuracies of several approaches are demonstrated using this case as benchmark. The best results are obtained with factorial estimation techniques such as the module costing technique, but the accuracies may diverge by up to +30%. Development of correlations and multiplication factors for ORC technology in particular is likely to improve the quality of the estimates.

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“…However, Heberle and Brüggemann [49,50] showed that ORC systems with pure i-butane as working fluid has a lower specific cost (in e·kW −1 ) than those with the i-butane + i-pentane working-fluid mixtures. Similarly, ORC systems with pure n-pentane or pure R-227ea were found to be cheaper than those with mixtures of n-pentane + n-hexane or R-245fa + R-227ea, respectively [51].…”

Section: Multi-objective Cost-power Optimizationmentioning

confidence: 99%

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

Cited by 79 publications

References 65 publications

Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

Cost Engineering Techniques and Their Applicability for Cost Estimation of Organic Rankine Cycle Systems

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

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