Hou Equation Of State Research Articles

Direct numerical simulations of homogeneous isotropic turbulence in a dense gas

A study of turbulence in BZT dense gas flows is performed using DNS. It is shown that for a large but realistic intensity, the turbulence in dense gas flows behaves in a highly compressible manner when the average thermodynamic state lies within the inversion region in which the gas fundamental derivative is negative. A close similarity is observed in the evolution of the kinetic energy when the initial turbulent Mach number and the Taylor Reynolds number are matched regardless of the Equation of State (EoS) considered. A large turbulent Mach number is yet more easily attained in dense gas flows lying in the inversion region because of the low speed of sound associated with it. In this case the turbulence shows a highly compressible evolution with periodic exchanges between the internal and kinetic energies. In order to assess the capabilities of currently available Large Eddy Simulation (LES) subgrid-scale models, a-posteriori tests are performed using the dynamic Smagorinsky model. Coherently with the hypothesis it relies on, the model perfectly captures the evolution of the kinetic energy when the turbulent Mach number is low enough. When using the perfect gas EoS at a higher turbulent Mach number the agreement is reasonable. Yet, when the average thermodynamic state lies within the inversion region and when using the thermal and caloric Martin&Hou EoS, the model is not able to capture the correct evolution of the kinetic energy. The results presented in this study call for a specific research effort directed towards the assessment and possibly the development of advanced subgrid-scale models for LES of turbulent dense gas flows.

Critical Flow of Dense Gases - Modeling and Experimental Validation*

Normal 0 21 The critical mass flow of dense gases strongly depends on real gas effects. In the present work the detailed assessment of the critical flow conditions and the limiting mass velocity in the flow of refrigerants has been experimentally verified. C ritical flow function C* data for R-410A and R-507A have been predicted based on Martin–Hou equation of state . The computational study was assured by implementation of theoretical model [1] for one dimensional (1D) and non-linear gas dynamic problems. This model, with the corrections for the boundary layer ( BL ) displacement thickness, gives a better prediction of the critical flow function than classical approach. Appropriate sonic flow conditions have been executed in the pressurized closed loop system by using ISO 9300 critical Venturi nozzle . Measurements of critical mass flow for dense superheated vapour of R-410A and R-507A carried out on laboratory test stand have confirmed the accuracy of the model and its physical significance. A main result of the investigations is a set of graphs C* ( T 0 , p 0 ) and tables for an assumed range of stagnation temperature T 0 and pressure p 0 at the upstream flow.

P−V−T Behavior of 2,3,3,3-Tetrafluoroprop-1-ene (HFO-1234yf) in the Vapor Phase from (243 to 373) K

The P−V−T properties of 2,3,3,3-tetrafluoroprop-1-ene (CF3CF═CH2, HFO-1234yf), an environmentally friendly refrigerant, were measured using a constant volume apparatus. Measurements were carried out at temperatures from (243 to 373) K and at pressures from (84 to 3716) kPa. A total of 136 experimental points, taken along 12 isochores, were obtained. Our experimental results were compared with a preliminary equation of state. The measurements were also regressed to the Martin−Hou equation of state. No other data on this fluid were found in the literature for the superheated region.

Applications of Associating Martin−Hou Equation of State to Vapor−Liquid Equilibria in the Critical Region or the Near-Critical Region

The associating Martin−Hou equation of state (AMH EOS) has been extended to high-pressure vapor−liquid equilibria calculations of alcohol-containing systems in the critical or near-critical region. The old mixing rules used in previous studies have been revised. The high-pressure vapor−liquid equilibria of some alcohol + hydrocarbon systems can be represented satisfactorily by the AMH EOS with the old mixing rules. However, the high-pressure vapor−liquid equilibria of alcohol + carbon dioxide systems and some other alcohol + hydrocarbon systems should be correlated well by the AMH EOS with the revised mixing rules. High-pressure vapor−liquid equilibria of two ternary systems that contain two alcohols and two nonassociating ternary systems are predicted from binary data.

Simultaneous Calculations of Excess Enthalpy and Vapor−Liquid Equilibria for Binary Carboxylic Acid + Carboxylic Acid Systems

An analytical expression for excess enthalpy of binary carboxylic acid + carboxylic acid systems based on the associating Martin−Hou equation of state (AMH EoS) is proposed and is applied to calcul...

Vapor−Liquid Equilibria for Ammonia + Methanol

Total pressure measurements for ammonia + methanol were made at 10 °C and 20 °C. The liquid and vapor compositions were derived by iteration from the material balance and the Martin−Hou equation of state.

Physical Properties of n-Perfluorobutane

A Martin--Hou equation of state has been obtained for n-perauorobutane applicable to 800 p.s.i.a., 170 deg and to a molar volume of 0.38 l/g mole. Vapor pressure and densities of liquid and saturated vapor were determined from -- 40 to 113.2 deg , the measured critical temperature. From this information the rectilinear diameter line and the heats of vaporization have been computed.