Influence of Heat Capacity Ratio on Pressure and Nozzle Flow of a Scramjets

2009 ◽  
Vol 25 (2) ◽  
pp. 303-311 ◽  
Author(s):  
C. Hirschen ◽  
A. Gülhan
Keyword(s):  
Heat Capacity ◽  
Nozzle Flow ◽  
Capacity Ratio

Analysis of heat capacity ratio on porous media in oscillating flow

2021 ◽  
Vol 179 ◽  
pp. 121724
Author(s):  
Armando Di Meglio ◽  
Elio Di Giulio ◽  
Raffaele Dragonetti ◽  
Nicola Massarotti
Keyword(s):  
Heat Capacity ◽  
Porous Media ◽  
Oscillating Flow ◽  
Capacity Ratio

Computation of Acoustic Velocity of Natural Gases With an Alternative Heat Capacity Ratio Equation and Application to Seismic Modeling

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Romulo Carvalho ◽  
Fernando Moraes
Keyword(s):  
Heat Capacity ◽  
Equations Of State ◽  
Acoustic Velocity ◽  
Fluid Composition ◽  
Seismic Modeling ◽  
Data Set ◽  
Natural Gases ◽  
Single Interface ◽  
Capacity Ratio ◽  
Extensive Experimental Data

Abstract We investigate three formulations for computing acoustic velocity of natural gas and derive an equation for the heat capacity ratio, which plays a central role in these formulations. The first formulation is a compilation of fundamental equations available in the engineering literature, referred to as the DASH formulation. The second formulation is a development from the first, in which we use the derived equation for the heat capacity ratio (modified DASH). The third formulation is a mainstream method implemented in Geoscience (BW formulation). All three formulations stem from virial Equations of State that take preponderance in the exploration stage, when the detailed fluid composition is unknown and compositional methods are frequently inapplicable. We test the formulations on an extensive experimental data set of acoustic velocity of natural gases and compare the resulting accuracies. Both DASH and modified DASH formulations provide significantly higher accuracy when compared to the BW formulation. Additionally, the modified DASH, as we derive in this work, has the highest accuracy at pressures above 7000 psi, a condition typically encountered in the Brazilian pre-salt reservoirs. In a final step, we investigate how these different formulations and corresponding accuracies in velocity computation may affect seismic modeling, using a single interface model between a dense gas reservoir and a sealing rock. A direct comparison of amplitude versus offset modeling using our modified DASH formulation and the BW formulation shows up to 50% difference in amplitude calculation in a sensitivity exercise, especially at the longer offsets and higher pressures.

scholarly journals The Triple Product Rule is Incorrect

2021 ◽  
Vol 1 (2) ◽  
pp. 1-3
Author(s):  
Igor Stepanov*
Keyword(s):  
Heat Capacity ◽  
Thermal Expansion ◽  
Isothermal Compressibility ◽  
Chain Rule ◽  
Triple Product ◽  
Product Rule ◽  
Capacity Ratio ◽  
The Difference ◽  
The Relationship ◽  
Derivatives Of

The triple product rule, also known as the cyclic chain rule, cyclic relation, cyclical rule or Euler's chain rule, relates the partial derivatives of three interdependent variables, and often finds application in thermodynamics. It is shown here that its derivation is wrong, and that this rule is not correct; hence, the Mayer's relation and the heat capacity ratio, which describe the difference between isobaric and isochoric heat capacities, are also untrue. Also, the relationship linking thermal expansion and isothermal compressibility is wrong. These results are confirmed by many experiments and by the previous theoretical findings of the author.

The Effect of Local Thermal Nonequilibrium on the Onset of Convection in a Nanofluid

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
D. A. Nield ◽  
A. V. Kuznetsov
Keyword(s):  
Heat Capacity ◽  
Brownian Motion ◽  
Small Particle ◽  
Lewis Number ◽  
Horizontal Layer ◽  
Onset Of Convection ◽  
Thermal Nonequilibrium ◽  
Capacity Ratio ◽  
Brownian Motion And Thermophoresis ◽  
Local Thermal Nonequilibrium

The onset of convection in a horizontal layer of a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis, and allows for local thermal nonequilibrium (LTNE) between the particle and fluid phases. The analysis reveals that in some circumstances, the effect of LTNE can be significant, but for a typical dilute nanofluid (with large Lewis number and with small particle-to-fluid heat capacity ratio), the effect is small.

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