Multiparameter equations of state for siloxanes: [(CH3)3-Si-O1/2]2-[O-Si-(CH3)2]i=1,…,3, and [O-Si-(CH3)2]6

Colonna, Piero; Nannan, N.R.; Guardone, Alberto

doi:10.1016/j.fluid.2007.10.001

Cited by 72 publications

(68 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The P eng − Robinson − Strijek − V era (PRSV) cubic equation of state (EoS) is considered to describe its thermodynamic behavior. The robustness of this equation with respect to more complex and potentially more accurate multi-parameter equations of state of the Span-Wagner type ( [5], [7], [4] has been discussed in [8] and [9]. Peng and Robinson (1976) proposed a cubic EoS of the form:…”

Section: Thermodynamic Modelsmentioning

confidence: 99%

“…These works show that nonclassical gasdynamic effects are generally very weak with respect to compression shock waves, and can occur only in a limited range of conditions. As shown for instance in [4] and [5], the accuracy of the thermodynamic model has a strong influence on the simulation of nonclassical phenomena, to the point that their presence can depend on the accuracy with which fluid model parameters are determined.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computation of tail probabilities for non-classical gasdynamic phenomena

Razaaly

Congedo

2017

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Abstract. This paper presents a novel method for computing the tail probability of a given quantity of interest by using only a low number of evaluations of the computer model, representing the problem of interest under uncertainties. This method is then applied to the study of rarefaction shock waves (RSW) in a dense-gas shock tube. It is well-known in literature that the prediction of a RSW is highly sensitive to uncertainties on the initial flow conditions. The objective of this work is to compute a very accurate estimation of the RSW probability of occurrence in a shock tube configuration.

show abstract

Section: Thermodynamic Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computation of tail probabilities for non-classical gasdynamic phenomena

Razaaly

Congedo

2017

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

show abstract

“…These complex equations, whose accuracy in computing the value of Γ has been discussed by Colonna et al (under review), have been applied to the selected linear and cyclic siloxane and perfluorocabons fluids listed in table 1, where relevant thermophysical properties are also reported for the reader's convenience. Additional information on the thermophysical properties of these fluids and their gasdynamic behaviour can be found in Nannan et al (2007) and Colonna et al ( , 2008b for siloxanes and Lambrakis & Thompson (1972), Cramer (1989Cramer ( , 1991 and Guardone & Argrow (2005) for perfluorocarbons. The minimum value of Γ obtained from the three thermodynamic models is also reported.…”

Section: Results For Selected Siloxanes and Perfluorocarbonsmentioning

confidence: 99%

“…However, despite the large dispersion of the results, the trend observed in § 3 is confirmed by the more complex thermodynamic model, namely the maximum pressure difference across an RSW slowly increases with Γ min for Γ min & −0.2. If the analysis is limited to the most recently developed thermodynamic model (see Span & Wagner 2003a,b;Colonna et al 2007Colonna et al , 2008b, which is arguably the most reliable, the RSW with maximum wave Mach number is obtained for fluid D 6 , for which one has M W 1.026.…”

Section: Results For Selected Siloxanes and Perfluorocarbonsmentioning

confidence: 99%

Maximum intensity of rarefaction shock waves for dense gases

2009

View full text Add to dashboard Cite

Modern thermodynamic models indicate that fluids consisting of complex molecules may display non-classical gasdynamic phenomena such as rarefaction shock waves (RSWs) in the vapour phase. Since the thermodynamic region in which non-classical phenomena are physically admissible is finite in terms of pressure, density and temperature intervals, the intensity of RSWs is expected to exhibit a maximum for any given fluid. The identification of the operating conditions leading to the RSW with maximum intensity is of paramount importance for the experimental verification of the existence of non-classical phenomena in the vapour phase and for technical applications taking advantage of the peculiarities of the non-classical regime. This study investigates the conditions resulting in an RSW with maximum intensity in terms of pressure jump, wave Mach number and shock strength. The upstream state of the RSW with maximum pressure drop is found to be located along the double-sonic locus formed by the thermodynamic states associated with an RSW having both pre-and post-shock sonic conditions. Correspondingly, the maximumMach thermodynamic and maximum-strength loci locate the pre-shock states from which the RSW with the maximum wave Mach number and shock strength can originate. The qualitative results obtained with the simple van der Waals model are confirmed with the more complex Stryjek-Vera-Peng-Robinson, Martin-Hou and Span-Wagner equations of state for selected siloxane and perfluorocarbon fluids. Among siloxanes, which are arguably the best fluids for experiments aimed at the generation and measurement of an RSW, the state-of-the-art Span-Wagner multiparameter equation of state predicts a maximum wave Mach number close to 1.026 for D 6 (dodecamethylcyclohexasiloxane, [O-Si-(CH 3 ) 2 ] 6 ). Such value is well within the capacity of the measurement system of a newly built experimental set-up aimed at the first-ever demonstration of the existence of RSWs in dense vapours.

show abstract

“…This modern equation of state allows accurate computations of all relevant thermodynamic properties over the entire thermodynamic range (even close to the critical point) with the accuracy required for design and analysis of advanced technical applications. Recently, 12-parameter equations of state of the Span-Wagner type for selected linear and cyclic siloxanes have become available, see and Colonna, Nannan & Guardone (2008b), and siloxanes were proposed as candidate BZT fluids, see Colonna & Silva (2003) and Colonna, Guardone & Nannan (2007). These fluids are light silicon oils currently used in Organic Rankine Cycle turbomachinery applications and considered as potential candidates for the experimental verification of the existence of nonclassical phenomena, see Zamfirescu et al (2006a, b) and Colonna et al (2008a).…”

Section: The Rarefaction Shocks Region Of Dense Gasesmentioning

confidence: 99%

Admissibility region for rarefaction shock waves in dense gases

2008

View full text Add to dashboard Cite

In the vapour phase and close to the liquid-vapour saturation curve, fluids made of complex molecules are expected to exhibit a thermodynamic region in which the fundamental derivative of gasdynamic Γ is negative. In this region, non-classical gasdynamic phenomena such as rarefaction shock waves are physically admissible, namely they obey the second law of thermodynamics and fulfil the speed-orienting condition for mechanical stability. Previous studies have demonstrated that the thermodynamic states for which rarefaction shock waves are admissible are however not limited to the Γ < 0 region. In this paper, the conditions for admissibility of rarefaction shocks are investigated. This results in the definition of a new thermodynamic region -the rarefaction shocks region -which embeds the Γ < 0 region. The rarefaction shocks region is bounded by the saturation curve and by the locus of the states connecting double-sonic rarefaction shocks, i.e. shock waves in which both the pre-shock and post-shock states are sonic. Only one double-sonic shock is shown to be admissible along a given isentrope, therefore the double-sonic states can be connected by a single curve in the volume-pressure plane. This curve is named the double sonic locus. The influence of molecular complexity on the shape and size of the rarefaction shocks region is also illustrated by using the van der Waals model; these results are confirmed by very accurate multi-parameter thermodynamic models applied to siloxane fluids and are therefore of practical importance in experiments aimed at proving the existence of rarefaction shock waves in the single-phase vapour region as well as in future industrial applications operating in the non-classical regime. IntroductionThe classical theory of gasdynamic discontinuities, see e.g. Hayes (1960), moves from the conservation laws in the shock reference frame to derive the well-known RankineHugoniot equation which relates the pressure P and the specific volume v past the shock wave for given values of P and v ahead of it. The observation -valid for the case of a constant-specific-heat (polytropic) ideal gas -that the curvature of the RankineHugoniot locus is always concave up, together with the condition that the specific entropy s must increase across the shock, leads to the conclusion that physically admissible shocks are of the compression type only, whereas rarefaction shock waves are not admissible. This results from noting that, for a polytropic ideal gas, isentropes are always concave-up in the (v, P )-plane and so are the Rankine-Hugoniot

show abstract

Multiparameter equations of state for siloxanes: [(CH3)3-Si-O1/2]2-[O-Si-(CH3)2]i=1,…,3, and [O-Si-(CH3)2]6

Cited by 72 publications

References 39 publications

Computation of tail probabilities for non-classical gasdynamic phenomena

Computation of tail probabilities for non-classical gasdynamic phenomena

Maximum intensity of rarefaction shock waves for dense gases

Admissibility region for rarefaction shock waves in dense gases

Contact Info

Product

Resources

About