Analysis of a carbon dioxide transcritical power cycle using a low temperature source

Cayer, Emmanuel; Galanis, Nicolas; Désilets, Martin; Nesreddine, Hakim; Roy, Philippe

doi:10.1016/j.apenergy.2008.09.018

Cited by 266 publications

(122 citation statements)

References 12 publications

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“…It is important to note that from Figures 5-7 it is clear that the expansion process does not follow a simple ideal gas model, and that the polytropic expansion index is critical in determining the correct engineering physics of such complicated devices as SCO2 expanders. The current findings of our research are in qualitative and quantitative agreement with previous studies of [15][16][17][18][19]. When comparing our current findings of 11% efficiency it should be kept in mind that herein we have assumed a nominal pinch-point in our heat exchanger on the order of 10 C in comparison to a pinch-point of 5 C assumed in [15,18].…”

Section: Resultssupporting

confidence: 90%

Method of Determining a Nominal Index Value for the Polytropic Expansion Process of Supercritical Carbon Dioxide in Piston-Cylinder Devices

Anderson

2014

Int. J. Thermo

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The polytropic process is a widely used pressure model for predicting the nature of pressure and volume states in expansion and compression systems. The two variable nature of this model typically leads to an open ended approach with heavy reliance on mechanism evaluation and potential extended design iterations in the prototyping phase. Through a fundamental examination of the polytropic derivation from the energy transfer ratio assumption, in conjunction with repeated application of elementary thermodynamic principles, including First Law analysis, moving boundary work, and substance property evaluation, a solution to a refined nominal polytropic index can be found. The derivation can provide valuable insight to the polytropic process itself and address the issue of bounding a complex system with a reasonable choice of theoretical system input. With the aid of the method outlined in this paper, researchers will be enabled with a tool to better predict the polytropic expansion coefficient which finds widespread use in thermodynamic modeling and analysis. To this end, the method is used herein to predict a polytropic index of n = 1.306 and k = 1.615 for the specific heat ratio for a SCO2 expansion engine operating between 20 MPa and 9.2 MPa.

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Section: Resultssupporting

confidence: 90%

Method of Determining a Nominal Index Value for the Polytropic Expansion Process of Supercritical Carbon Dioxide in Piston-Cylinder Devices

Anderson

2014

Int. J. Thermo

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“…Specifically the type of heat exchanger (plate, shell and tubes, etc. ), the size of its parts as well as correlations for the calculation of heat transfer coefficients are the minimum requirements for the evaluation of U as illustrated in [12] and [19]. Table 2 shows the optimization results for R134a and a source temperature of 100 C.…”

Section: Resultsmentioning

confidence: 99%

Optimal Design of ORC Systems with a Low-Temperature Heat Source

Khennich

Galanis

2012

Entropy

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A numerical model of subcritical and trans-critical power cycles using a fixed-flowrate low-temperature heat source has been validated and used to calculate the combinations of the maximum cycle pressure (P ev ) and the difference between the source temperature and the maximum working fluid temperature (DT) which maximize the thermal efficiency (η th ) or minimize the non-dimensional exergy losses (β), the total thermal conductance of the heat exchangers (UA t ) and the turbine size (SP). Optimum combinations of P ev and DT were calculated for each one of these four objective functions for two working fluids (R134a, R141b), three source temperatures and three values of the non-dimensional power output. The ratio of UA t over the net power output (which is a first approximation of the initial cost per kW) shows that R141b is the better working fluid for the conditions under study.

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“…The solar collector field includes two glass cover flat plate collectors to absorb solar radiation, thermal storage tank to provide stable heat and avoid any fluctuations due to sudden changes in solar radiation over the day. An auxiliary heater is used to help thermal storage tank to satisfy its minimum temperature, even at the times without sufficient irradiation [7]. Within transcritical power cycle, the temperature of CO 2 climbs in a vapor generator, and then turns into subcritical state after producing mechanical power as it goes through the turbine.…”

Section: System Descriptionmentioning

confidence: 99%

“…Xia et al [6] performed a thermodynamic analysis and optimization on a solarpowered transcritical power cycle with liquefied natural gas heat sink for reverse osmosis desalination and the results showed that one of the most exergy losses take places in the condenser. Cayer et al [7] applied four methodologies on a carbon-dioxide power cycle with a low-grade energy of process gases as heat source. Furthermore, authors [8] performed a parametric optimization by taking some parameters including the relative cost of the system as performance pointers.…”

Section: Introductionmentioning

confidence: 99%

Exergy analysis of a hydrogen and water production process by a solar-driven transcritical CO 2 power cycle with Stirling engine

Naseri

Bidi

Ahmadi

et al. 2017

Journal of Cleaner Production

113

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 A novel cogeneration plant including Stirling engine to produce water and hydrogen. A dynamic RO model including recovery turbine for different permeate flow rate. About 8% reduction in exergy destruction in the system using ideal Stirling engine. More electrical power production, higher than both LNG and CO 2 power cycle. Electrolyzer-based ZLD approach by employing electrolyzer beside RO desalination. ACCEPTED MANUSCRIPT AbstractThis study attempts to go beyond the conventional framework of the integrated solar transcritical CO 2 power cycle works, aimed at further utilization of available exergy as much as possible. This paper proposed a novel system for hydrogen and fresh water production in which a Stirling engine used instead of a condenser, for the places with abundant access to solar radiation and sea, and least to freshwater sources. This proposal leads to further utilization of streams' exergy through the system instead of wasting to the environment, and further power production by the engine followed by the higher products. The electrolyzer employed beside Reverse Osmosis (RO) desalination system, and takes full advantages of highly concentrated brine stream of desalination, eliminating the wastewater rejection through proposed system leading to attaining a near-ZLD approach in fresh water and hydrogen production. This reduces the adverse impacts of desalination's wastewater on the environment. A thermodynamic and exergy analysis is carried out to compare the superiority of this study and investigate the effect of some key parameters on the overall performance of the system as well. The results showed that replacing the condenser by a Stirling engine reduces the exergy destruction through heat transfer from CO 2 to an LNG unit. Exergy destruction was reduced from 16.7% to 8.8% for the above configuration for an ideal Stirling engine that exploits it to produce extra power which its minimum is at least 9 kW and 15 kW higher than CO 2 and LNG power productions.Moreover, Entering RO brine stream, wasting 2.58 kW exergy, to the electrolyzer leads toNaClO and H 2 production besides removing brine stream. In a power plant, sodium hypochlorite is used for disinfection of cooling systems and hydrogen can be used as a source of energy in fuel cells. An examination of some thermodynamic factors showed that higher ACCEPTED MANUSCRIPT 2 CO 2 turbine inlet pressure has an optimum value in producing fresh water and hydrogen, while the higher CO 2 turbine inlet temperature slightly reduces the productions rate. The more recovery ratio also causes a sharp reduction in hydrogen production, whereas it has an optimum amount of fresh water production at recovery ratio equals to 0.47.

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Analysis of a carbon dioxide transcritical power cycle using a low temperature source

Cited by 266 publications

References 12 publications

Method of Determining a Nominal Index Value for the Polytropic Expansion Process of Supercritical Carbon Dioxide in Piston-Cylinder Devices

Method of Determining a Nominal Index Value for the Polytropic Expansion Process of Supercritical Carbon Dioxide in Piston-Cylinder Devices

Optimal Design of ORC Systems with a Low-Temperature Heat Source

Exergy analysis of a hydrogen and water production process by a solar-driven transcritical CO 2 power cycle with Stirling engine

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