Zeotropic mixtures as working fluids in Organic Rankine Cycles for low-enthalpy geothermal resources

Heberle, Florian; Preißinger, Markus; Brüggemann, Dieter

doi:10.1016/j.renene.2011.06.044

Cited by 289 publications

(143 citation statements)

References 16 publications

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“…when the temperature glide of condensation matches the temperature increase of the cooling water [5]. For the OSC the temperature glide of condensation (∆T g ) is only close to the temperature increase of the cooling water for butane/isopentane and propane/isobutane.…”

Section: Resultsmentioning

confidence: 95%

“…This enables a reduction in the temperature difference between the heat exchanging streams both for the condenser and the boiler resulting in an increase in cycle performance [4]. Analyses of the irreversibilities in the cycle components have identified the condenser as achieving the largest benefits from the non-isothermal phase-change, and the mixture composition minimizing the condenser losses tends to coincide with the composition which maximizes cycle performance [5,6]. In a recent study, Weith et al [7] investigated the potential of using a siloxane mixture (MM/MDM) as the working fluid for an ORC utilizing the 460 • C exhaust heat from a biogas engine.…”

Section: Introductionmentioning

confidence: 99%

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Design and optimization of a novel organic Rankine cycle with improved boiling process

Andreasen¹,

Larsen

Knudsen³

et al. 2015

Energy

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In this paper we present a novel organic Rankine cycle layout, named the organic splitcycle, designed for utilization of low grade heat. The cycle is developed by implementing a simplified version of the split evaporation concept from the Kalina split-cycle in the organic Rankine cycle in order to improve the boiling process. Optimizations are carried out for eight hydrocarbon mixtures for hot fluid inlet temperatures at 120 • C and 90 • C, using a genetic algorithm to determine the cycle conditions for which the net power output is maximized. The most promising mixture is an isobutane/pentane mixture which, for the 90 • C hot fluid inlet temperature case, achieves a 14.5 % higher net power output than an optimized organic Rankine cycle using the same mixture. Two parameter studies suggest that optimum conditions for the organic split-cycle are when the temperature profile allows the minimum pinch point temperature difference to be reached at two locations in the boiler. Compared to the transcritical organic Rankine cycle, the organic split-cycle improves the boiling process without an entailing increase in the boiler pressure, thus enabling an efficient low grade heat to power conversion at low boiler pressures.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Design and optimization of a novel organic Rankine cycle with improved boiling process

Andreasen¹,

Larsen

Knudsen³

et al. 2015

Energy

View full text Add to dashboard Cite

show abstract

“…TIP range is 9 Figure 4: Location of Brent Province in North Viking Graben reproduced with permission from the Geological Society [16] restricted to 0.01 P crit < TIP < 0.8 P crit . The lower limit is selected to ensure the condenser vacuum was practically achievable and the upper limit of the TIP is set to limit error incurred by fluid properties uncertainty near the critical point (P crit ) in accordance with Herberle et al [18]. Similarly the working fluid mass flow rate (ṁ o ) is limited to 0.4ṁ s <ṁ o < 2.5ṁ s , whereṁ s is the mass flow rate of hot brine, to keep the quantity of working fluid within practically achievable limits.…”

Section: Orc Modelling Methodologymentioning

confidence: 99%

Power production via North Sea Hot Brines

Auld¹,

Hogg²,

Berson³

et al. 2014

Energy

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“…The zeotropic mixture has a character of "temperature slip", which can benefit the heat transfer between cold and hot fluids, thus reducing the irreversible loss caused by the heat transfer temperature difference [23]. ORC systems that use mixed working fluids may have better running performances than pure working fluids [24][25]. Mixed working fluids have drawn the attention of several scholars [26][27].…”

Section: Introductionmentioning

confidence: 99%

Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC) Systems for Vehicle Diesel Engines

Yang

Zhang

Wang

et al. 2014

Entropy

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Abstract:One way to increase the thermal efficiency of vehicle diesel engines is to recover waste heat by using an organic Rankine cycle (ORC) system. Tests were conducted to study the running performances of diesel engines in the whole operating range. The law of variation of the exhaust energy rate under various engine operating conditions was also analyzed. A diesel engine-ORC combined system was designed, and relevant evaluation indexes proposed. The variation of the running performances of the combined system under various engine operating conditions was investigated. R245fa and R152a were selected as the components of the mixed working fluid. Thereafter, six kinds of mixed working fluids with different compositions were presented. The effects of mixed working fluids with different compositions on the running performances of the combined system were revealed. Results show that the running performances of the combined system can be improved effectively when mass fraction R152a in the mixed working fluid is high and the engine operates with high power. For the mixed working fluid M1 (R245fa/R152a, 0.1/0.9, by mass fraction), the net power output of the combined system reaches the maximum of 34.61 kW. Output energy density of working fluid (OEDWF), waste heat recovery OPEN ACCESSEntropy 2014, 16 4770 efficiency (WHRE), and engine thermal efficiency increasing ratio (ETEIR) all reach their maximum values at 42.7 kJ/kg, 10.90%, and 11.29%, respectively.

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Zeotropic mixtures as working fluids in Organic Rankine Cycles for low-enthalpy geothermal resources

Cited by 289 publications

References 16 publications

Design and optimization of a novel organic Rankine cycle with improved boiling process

Design and optimization of a novel organic Rankine cycle with improved boiling process

Power production via North Sea Hot Brines

Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC) Systems for Vehicle Diesel Engines

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