Performance analysis in near-critical conditions of organic Rankine cycle

Pan, Lisheng; Wang, Huaixin; Shi, Weixiu

doi:10.1016/j.energy.2011.11.033

Cited by 47 publications

(22 citation statements)

References 15 publications

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“…[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]. Here, we focus on a binary system in which the geothermal stream is in the form of a hot and pressurized liquid, referred to as geothermal brine (GB).…”

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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Section: Introductionmentioning

confidence: 99%

Modeling and optimization of a binary geothermal power plant

Ghasemi

Paci

Tizzanini

et al. 2013

Energy

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“…If this shift was not taken note of, an obviously jump for the cycle performance could be achieved in the nearcritical condition, as shown in Fig. 1a [12]. However, in fact, the parameters varied continuously in the transition from the subcritical conditions to the supercritical conditions, as shown in Fig.…”

Section: Nomenclaturementioning

confidence: 91%

“…Pinch point is of importance Fig. 1 The impact of the misjudgment of the pinch point position on the analysis result [12,13] for analyzing the heat transfer process. The pinch point is usually specified as the bubble point in evaporator, as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Investigation on the pinch point position in heat exchangers

Pan

Shi

2016

J. Therm. Sci.

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The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shifts to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supercritical heater when the heat source fluid temperature is very high compared with the absorbing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the iterative method in all conditions rather than taking for granted.

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“…A wrong selection of working fluid could lead to a less efficient and expensive plant generation unit. Some selection criteria have been put forward by various authors [2][3][4][5][6][7][8][9][10][11], incorporating thermodynamic properties, provided in literature but these do not have a general character. Authors also worked on the topic of working fluid selection and developed a thermodynamic criterion for wet fluids [12].…”

Section: Introductionmentioning

confidence: 99%

“…In the analysis the cost of heat exchangers surface contributes largely to the power plant cost. Therefore, the performance of the power plant can be optimized using the optimization criterion similar to thosegiven in [1][2][3], where the ratio of total heat transfer area to total net power is considered to be the objective function. In our analysis the temperature of condensation is assumed as constant and equal to 30 o C. Hence the change of heat exchange area of condenser does not influence markedly the optimal boiling temperature in a cycle for the given working fluid.…”

Section: Introductionmentioning

confidence: 99%

Optimal boiling temperature for ORC installation

Mikielewicz¹,

Mikielewicz²

2012

Archives of Thermodynamics

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In the paper a research on cost-effective optimum design boiling temperature for Organic Rankine Cycle utilizing low-temperature heat sources is presented. The ratio of the heat exchanger area of the boiler to the power output is used as the objective function. Analytical relations for heat transfer area as well power of the cycle are formulated. Evaporation temperature and inlet temperature of the heat source medium as well its mass flow rate are varied in the optimization method. The optimization is carried out for three working fluids, i.e. R 134a, water and ethanol. The objective function (economics profitability, thermodynamic efficiency) leads to different optimal working conditions in terms of evaporating temperature. Maximum power generation in the near-critical conditions of subcritical ORC is the highest. The choice of the working fluid can greatly affect the objective function which is a measure of power plant cost. Ethanol exhibits a minimum objective function but not necessarily the maximum cycle efficiency.

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Performance analysis in near-critical conditions of organic Rankine cycle

Cited by 47 publications

References 15 publications

Modeling and optimization of a binary geothermal power plant

Modeling and optimization of a binary geothermal power plant

Investigation on the pinch point position in heat exchangers

Optimal boiling temperature for ORC installation

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