Exergy analysis on throttle reduction efficiency based on real gas equations

Luo, Yuxi; Wang, Xuanyin

doi:10.1016/j.energy.2009.09.008

Cited by 34 publications

(16 citation statements)

References 17 publications

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“…(5) (the kinetic energy and gravitational potential energy are ignored) and with the equations of the enthalpy and internal energy [15], the polytropic exponent of the air in a container can be calculated.…”

Section: Calculation Formulasmentioning

confidence: 99%

Study of polytropic exponent based on high pressure switching expansion reduction

Wang

Luo

2011

J. Therm. Sci.

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Switching expansion reduction (SER) uses a switch valve to substitute the throttle valve to reduce pressure for high pressure pneumatics. The experiments indicate that the simulation model well predicts the actual characteristics. The heat transfers and polytropic exponents of the air in expansion tank and supply tanks of SER have been studied on the basis of the experiments and the simulation model. Through the mathematical reasoning in this paper, the polytropic exponent can be calculated by the air mass, heat, and work exchanges of the pneumatic container. For the air in a constant volume tank, when the heat-absorption is large enough to raise air temperature in discharging process, the polytropic exponent is less than 1; when the air is experiencing a discharging and heat-releasing process, the polytropic exponent exceeds the specific heat ratio (the value of 1.4).

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Section: Calculation Formulasmentioning

confidence: 99%

Study of polytropic exponent based on high pressure switching expansion reduction

Wang

Luo

2011

J. Therm. Sci.

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“…And the exergy is vaguely defined as a universal measure of the work potential or quality of different forms of energy in relation to a given environment [13] . In 2010, we proposed an equation to calculate the exergy of real gases and evaluated the real gas effect on exergy of compressed air [14] . This paper studies the internal energy, enthalpy and exergy transfer characteristics of switching expansion reduction (SER) comparatively.…”

Section: Introductionmentioning

confidence: 99%

Enthalpy and exergy transfers of high pressure switching expansion reduction

Luo

Wang

Lei

2012

J. Shanghai Jiaotong Univ. (Sci.)

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The energy balance, air internal energy, enthalpy and exergy transfers of high pressure switching expansion reduction (SER) are comparatively analyzed in this paper to give a better understanding about the exergy analysis and its difference between energy conversion analyses for the pneumatics. In SER, the exergy transfer efficiency is much lower than the enthalpy efficiency. The enthalpy efficiency is primarily related to the initial pressure of supply tanks, and the exergy efficiency is primarily related to the pressure reduction ratios. Heat transfers increase the internal energy, enthalpy and exergy of air; the influence on exergy is relatively small. The total enthalpy in SER decreases as the air temperature decreases in the expansion process of the air. And exergy loss is primarily related to the irreversible process of isenthalpic throttling but not energy conversion. Based on the analyses, to improve the exergy efficiency of the pneumatics, the pressure reduction without power output should be avoided.

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“…It was proposed in 1976 [12,13]: In the general high pressure pneumatic system, the pressure can reach 30 MPa, and the temperature range is about 250 K< T <400 K. Compared with the Nelson-Obert's generalized compressibility chart [1], the P-R equation is more precise than the S-R-K equation in the compressibility factor calculation of air [1]. In this paper we calculate the compressibility factor, using improved virial and P-R equations.…”

Section: Derivation and Determination Of Real Gas Equation Of State Fmentioning

confidence: 99%

“…Compared to petroleum or electric systems, high pressure air has the advantages of no pollution, high power density, cheapness, reliable performance, recycling use, and being easy to maintain [1,2]. It has been applied to industrial automation, robot driving, compressed air powered vehicles, and even some special industries such as aeronautics, astronautics, and weapons design [3].…”

Section: Introductionmentioning

confidence: 99%

Pneumatic Performance Study of a High Pressure Ejection Device Based on Real Specific Energy and Specific Enthalpy

Ren

Yang

et al. 2014

Entropy

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Abstract:In high-pressure dynamic thermodynamic processes, the pressure is much higher than the air critical pressure, and the temperature can deviate significantly from the Boyle temperature. In such situations, the thermo-physical properties and pneumatic performance can't be described accurately by the ideal gas law. This paper proposes an approach to evaluate the pneumatic performance of a high-pressure air catapult launch system, in which esidual functions are used to compensate the thermal physical property uncertainties of caused by real gas effects. Compared with the Nelson-Obert generalized compressibility charts, the precision of the improved virial equation of state is better than Soave-Redlich-Kwong (S-R-K) and Peng-Robinson (P-R) equations for high pressure air. In this paper, the improved virial equation of state is further used to establish a compressibility factor database which is applied to evaluate real gas effects. The specific residual thermodynamic energy and specific residual enthalpy of the high-pressure air are also derived using the modified corresponding state equation and improved virial equation of state which are truncated to the third virial coefficient. The pneumatic equations are established on the basis of the derived residual functions. The comparison of the numerical results shows that the real gas effects are strong, and the pneumatic performance analysis indicates that the real dynamic thermodynamic process is obviously different from the ideal one.

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Exergy analysis on throttle reduction efficiency based on real gas equations

Cited by 34 publications

References 17 publications

Study of polytropic exponent based on high pressure switching expansion reduction

Study of polytropic exponent based on high pressure switching expansion reduction

Enthalpy and exergy transfers of high pressure switching expansion reduction

Pneumatic Performance Study of a High Pressure Ejection Device Based on Real Specific Energy and Specific Enthalpy

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