Efficiency optimization potential in supercritical Organic Rankine Cycles

Schuster, Andreas; Karellas, Sotiriοs; Aumann, Richard

doi:10.1016/j.energy.2009.06.019

Cited by 321 publications

(125 citation statements)

References 12 publications

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“…Examples include the flows in Rankine cycle power systems using steam as a working fluid as well as systems which employ non-aqueous working fluids. The latter working fluids tend to be advantageous when non-fossil fuel heat sources are used; see, for example, the studies of organic Rankine cycles by Curran, 6 Devotta and Holland, 7 Yan, 8 Hung, Shai, and Wang, 9 Liu, Chien, and Wang, 10 Wei et al, 11 Saleh et al, 12 and Shuster, Karellas, and Aumann 13 or the studies of Dostal et al, 14,15 Dostal, 16 Moisseytsev, 17 Moisseytsev and Sienicki, 18 and Sarkar 19,20 on the use of CO 2 and N 2 O for nuclear power systems. Even if the working fluid is steam, our examination of the literature indicates that no estimates of the bulk viscosity are currently available for water vapor.…”

Section: Introductionmentioning

confidence: 99%

Numerical estimates for the bulk viscosity of ideal gases

Cramer

2012

Physics of Fluids

178

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We estimate the bulk viscosity of a selection of well known ideal gases. A relatively simple formula is combined with published values of rotational and vibrational relaxation times. It is shown that the bulk viscosity can take on a wide variety of numerical values and variations with temperature. Several fluids, including common diatomic gases, are seen to have bulk viscosities which are hundreds or thousands of times larger than their shear viscosities. We have also provided new estimates for the bulk viscosity of water vapor in the range 380–1000 K. We conjecture that the variation of bulk viscosity with temperature will have a local maximum for most fluids. The Lambert-Salter correlation is used to argue that the vibrational contribution to the bulk viscosities of a sequence of fluids having a similar number of hydrogen atoms at a fixed temperature will increase with the characteristic temperature of the lowest vibrational mode.

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Section: Introductionmentioning

confidence: 99%

Numerical estimates for the bulk viscosity of ideal gases

Cramer

2012

Physics of Fluids

178

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“…The characteristics of a thermal energy source affects the optimal choice of working fluid (WF) for an ORC (e.g. [10][11][12][13][14][15][16][17][18][19][20]). Different objective functions have been used for WF selection, such as the ratio of net power output to heat exchanger area (Ẇ net /A) [10], net power output (Ẇ net ) [14,19,21,22] and first or second law efficiencies [7, 11-13, 16-18, 20].…”

Section: Introductionmentioning

confidence: 99%

Modeling and optimization of a binary geothermal power plant

Ghasemi

Paci

Tizzanini

et al. 2013

Energy

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6A model is developed for an existing organic Rankine cycle (ORC) utilizing a low temperature geothermal source. The model is implemented in Aspen Plus ® and used to simulate the performance of the existing ORC equipped with an air-cooled condensation system. The model includes all the actual characteristics of the components. The model is validated by approximately 5000 measured data in a wide range of ambient temperatures. The net power output of the system is maximized. The results suggest different optimal operation strategies based on the ambient temperature. Existing literature claims that no superheat is optimal for maximum performance of the system; this is confirmed only for low ambient temperatures. For moderate ambient temperatures (T amb ≥ 1.7 ) superheat maximizes net power output of the system. The value of the optimal superheat increases with increasing ambient temperature.The optimal operation boosts the total power produced in a year by 9%. In addition, a simpler and semi-analytic model is developed that enables very quick optimization of the operation of the cycle. Based on the pinch condition at the condenser, a simple explicit formula is derived that predicts the outlet pressure of the turbine as a function of mass flow rate of working fluid.

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“…For this reason, both steady-state and dynamic simulation of the supercritical ORC-WHR system is necessary before testing the real system. The investigation of steady-state modelling of the supercritical ORC-WHR system has been presented in several reports (Chowdhury et al, 2015a andGao et al, 2012;Glover et al, 2015a andKarellas et al, 2012;Schuster et al, 2010 ). However, most of these focused on the fluid selection (Gao et al, 2012;Glover et al, 2015a;Schuster et al, 2010); design, optimization and performance analysis (Schuster et al, 2010;Karellas et al, 2012;Chowdhury et al, 2015a andGlover et al, 2015b).…”

Section: Introductionmentioning

confidence: 99%

“…Saleh et al (2007) presented the performance analysis of the ORC for a geothermal application with regards to 31 pure organic fluids. The selection of best working fluids with respect to different applications have been studied thoroughly and the outcomes of the investigations can be found elsewhere (Schuster et al, 2010;Gao et al, 2012;Saleh et al, 2007;Chen et al, 2010;Glover et al, 2015a;PalmaFlores et al, 2015;Shu et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The operating pressure of the subcritical ORC is below the critical pressure of the working fluid; while the supercritical ORC is run at a pressure higher than the critical pressure. The investigations on supercritical ORC carried out by Glover et al (2014), Gao et al (2012), Shu et al (2014) and Schuster et al (2010) show that the heat addition to the working fluid at supercritical pressure, instead of subcritical pressure, can lead to a higher cycle efficiency. This is primarily due to the higher net power output and lower exergy losses.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

Chowdhury

Nguyen

Thornhill

2017

Int.J Automot. Technol.

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ABSTRACTThe supercritical Organic Rankine Cycle (ORC) for the Waste Heat Recovery (WHR) from Internal Combustion (IC) engines has been a growing research area in recent years, driven by the aim to enhance the thermal efficiency of the ORC and engine. Simulation of a supercritical ORC-WHR system before a real-time application is important as high pressure in the system may lead to concerns about safety and availability of components. In the ORC-WHR system, the evaporator is the main contributor to thermal inertia of the system and is considered to be the critical component since the heat transfer of this device influences the efficiency of the system. Since the thermophysical properties of the fluid at supercritical pressures are dependent on temperature, it is necessary to consider the variations in properties of the working fluid. The well-known Finite Volume (FV) discretization method is generally used to take those property changes into account. However, a FV model of the evaporator in steady state condition cannot be used to predict the thermal inertia of the cycle when it is subjected to transient heat sources. In this paper, a dynamic FV model of the evaporator has been developed and integrated with other components in the ORC-WHR system. The stability and transient responses along with the performance of the ORC-WHR system for the transient heat source are investigated and are also included in this paper.

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Efficiency optimization potential in supercritical Organic Rankine Cycles

Cited by 321 publications

References 12 publications

Numerical estimates for the bulk viscosity of ideal gases

Numerical estimates for the bulk viscosity of ideal gases

Modeling and optimization of a binary geothermal power plant

Dynamic model of supercritical Organic Rankine Cycle waste heat recovery system for internal combustion engine

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