• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.31-34
• /
• 2012

Numerical simulations of the steady and unsteady state were conducted for a coaxial swirl injector with Kerosene fuel. Non-premixed equilibrium model based on chemical equilibrium assumption was used as turbulence-chemistry interaction model. As an equations of state, SRK(Soave-Redlich-Kwong) EOS was applied to deal with the behavior of real fluid in a high pressure condition. Through the steady and unsteady computations, mean values of steady and time-averaged unsteady state were compared on the temperature and OH mass fraction and it was shown that the flame structure of steady state was different to that of time-averaged unsteady state.

• Textile Coloration and Finishing
• /
• v.33 no.3
• /
• pp.141-146
• /
• 2021

Supercritical fluid has excellent dissolving power for various materials based on low viscosity and high diffusion coefficient and is used as solvents in various chemical processes. However, its industrial application can be very tricky because the design, especially the size of the supercritical apparatus, should be carefully chosen to optimize the cost and the production of supercritical fluidic state. And the first step of the supercritical fluid apparatus design is to choose the appropriate size of the reactor vessel to produce supercritical fluid above its critical pressure and temperature. Therefore, this study aims to analyze thermodynamic behaviors of dichloromethane based on ideal gas, van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, and Peng-Robinson equations of state. The correlation between the volume and pressure of dichloromethane at 200℃ was revealed and it can be used to design the optimized size of the supercritical apparatus for industrial production.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.74.2-74.2
• /
• 2011

A simulation study on synthesis gas process in GTL process was carried out in order to find optimum operation conditions for GTL (gas-to-liquid) pilot plant design. Optimum operating conditions for synthesis gas process were determined by changing reaction variables such as feed temperature and pressure. During the simulation, overall synthesis process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Simulation results were also compared to experimental results to confirm the reliability of simulation model. Simulation results were reasonably well matched with experimental results.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.6
• /
• pp.48-58
• /
• 2013

Characteristics of thermophysical properties and flow structures in a swirl injector at supercritical pressure have been investigated using the kerosene surrogate consisting of four species and various ideal and real gas equations of state. The quantitative comparisons of thermophysical properties for equations of state have been performed. Also, a large eddy simulation and preconditioning technique for getting an effective convergence rate are applied to analyze turbulent flow in a swirl injector. The flow characteristics in the injector has significantly different behaviors depending on the equations of state due to the different thermophysical properties in the injector. The Redlich-Kwong-Peng-Robinson equation of state provides the most suitable results in the wide range of temperature.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.136.2-136.2
• /
• 2011

A dynamic simulation study on SCR process in GTL process was carried out in order to find optimum operation conditions for pilot plant operation. Optimum operating conditions for SCR synthesis gas process were determined by changing operation variables such as feed temperature and pressure. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Dynamic simulation results were fed back to feed operation condition for optimizing productivity, especially for appropriate condition to FT (Fischer-Tropsch) synthesis unit.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.5
• /
• pp.395-400
• /
• 2019

Comparative studies between single- and two-stage refrigeration cycle using propane as a refrigerant have been performed for a vapor recompression refrigeration cycle. PRO/II with PROVISION release 10.2 from AVEVA company was used, and the Soave-Redlich-Kwong equation of state model with Twu's alpha function was selected for the modeling and optimization of the refrigeration cycle for the reliquefaction of BOG coming out from the LPG storage tank. In two-stage refrigeraton cycle, 24.8% of compressor power was reduced compared to that of single-stage refrigeration cycle through the optimization works.

• Korean Chemical Engineering Research
• /
• v.54 no.3
• /
• pp.350-359
• /
• 2016

For accurate estimation over the change of pressure and temperature of the vessel during blowdown period, a new dynamic blowdown model was developed in this work. In particular, heat transfer from the vessel wall to discharge gas at both laminar or turbulent flow in the vessel was embedded to the model to increase the accuracy of blowdown estimation. For thermodynamics, the whole blowdown period was discretized into finite pressure decrement steps, and the step size was adjusted so that the calculation can be more efficiently carried out, while maintaining the model's accuracy. Both Peng-Robinson and Soave-Redlich-Kwong equation of states were applied to the model, and the results were compared each other. Finally, the simulation results was compared with Haque and coworkers' experimental results, and it proved high accuracy of the model.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3003-3008
• /
• 2007

Critical nozzle has been frequently employed to measure the flow rate of various gases, but hydrogen gas, especially being at high-pressure condition, was not nearly dealt with the critical nozzle due to treatment danger. According to a few experimental data obtained recently, it was reported that the discharge coefficient of hydrogen gas through the critical nozzle exceeds unity in a specific range of Reynolds number. No detailed explanation on such an unreasonable value was made, but it was vaguely inferred as real gas effects. For the purpose of practical use of high-pressure hydrogen gas, systematic research is required to clarify the critical nozzle flow of high-pressure hydrogen gas. In the present study, a computational fluid dynamics(CFD) method has been applied to predict the critical nozzle flow of high-pressure hydrogen gas. Redlich-Kwong equation of state that take account for the forces and volume of molecules of hydrogen gas were incorporated into the axisymmetric, compressible Navier-Stokes equations. A fully implicit finite volume scheme was used to numerically solve the governing equations. The computational results were validated with some experimental data available. The results show that the coefficient of discharge coefficient is mainly influenced by the compressibility factor and the specific heat ratio, which appear more remarkable as the inlet total pressure of hydrogen gas increases.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.10
• /
• pp.1279-1287
• /
• 2004

The vaporization characteristics of a liquid heptane droplet in a supercritical nitrogen flow are numerically studied. The transient conservation equations of mass, momentum, energy, and species are expressed in an axisymmetric coordinate system. The governing equations are solved time marching method with preconditioning scheme. The modified Soave-Redlich-Kwong equation of state is employed for taking account of real gas effects such as thermodynamic non-ideality and transport anomaly. Changing the convective velocity and ambient pressure, several parametric studies are conducted. The numerical results show that the two parameters, Reynolds number and dimensionless combined parameter(${\mu}$s/${\mu}$d)(equation omitted), have influence on supercritical droplet vaporization.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.11
• /
• pp.1595-1603
• /
• 2003

Droplet combustion at high ambient pressures is studied numerically by formulating one dimensional combustion model in the mixture of n-heptane fuel and air. The ambient pressure is supercritical conditions. The modified Soave-Redlich-Kwong state equation is used in the evaluation of thermophysical properties to account for the real gas effect on fluid p-v-T properties in high pressure conditions. Non-ideal thermodynamic and transport property at near critical and supercritical conditions are also considered. Several parametric studies are performed by changing ambient pressure and initial droplet diameter. Droplet lifetime decreased with increasing pressure. Surface temperature increased with increasing pressure. Ignition time increased with increasing initial droplet diameter. Temporal or spatial distribution of mass fraction, mass diffusivity, Lewis number, thermal conductivity, and specific heat were presented.