Numerical Study on Evaporation Characteristics of Single Urea-Water Solution (UWS) Droplet and Variation of Evaporation and Wall-Interaction Characteristics of UWS Spray with Cell Density in SCR Mixing Chamber

2016 ◽  
Author(s):  
Sadashiva Prabhu S ◽  
Nagaraj S Nayak ◽  
N. Kapilan
Keyword(s):  
Cell Density ◽  
Numerical Study ◽  
Water Solution ◽  
Mixing Chamber ◽  
Wall Interaction

3-D Numerical Study of Effect of Flow Parameters upon the Uniformity of NH3 in Urea-SCR

2012 ◽  
Vol 505 ◽  
pp. 175-179 ◽  
Author(s):  
R. Vikas ◽  
J.M. Mallikarjuna ◽  
V. Ganesan
Keyword(s):  
Catalytic Reduction ◽  
Numerical Study ◽  
Water Solution ◽  
Injection Pressure ◽  
Exhaust Gas ◽  
Oxides Of Nitrogen ◽  
Lean Burn ◽  
Flow Parameters ◽  
Ammonia Slip ◽  
Engine Emission

Nowadays, due to the stringent engine emission norms, an efficient technique is required to reduce oxides of nitrogen (NOX) from automobiles especially from the lean burn engines. Although Urea Selective Catalytic Reduction (SCR) is capable of satisfying these norms, the ammonia slip nullifies its advantages. Ammonia slip is mainly due to the lack of uniformity of ammonia at the monolith entrance. The uniformity of ammonia distribution mainly depends upon the flow parameters of exhaust gas and the injection parameters of urea water solution. The current study addresses the effect of flow parameters, temperature and flow rate of exhaust gas on the injection pressure. The results obtained reveals useful guidelines for enhancing the uniformity of ammonia in Urea-SCR.

scholarly journals Numerical Study of the Instability and Flow Transition in a Vortex-Ring/Wall Interaction

2016 ◽  
Vol 9 (7) ◽  
pp. 2299-2309
Author(s):  
Heng Ren ◽  
G. X. Zhang ◽  
H. S. Guan ◽  
◽  
◽  
...  
Keyword(s):  
Vortex Ring ◽  
Numerical Study ◽  
Flow Transition ◽  
Wall Interaction

scholarly journals A Numerical Study on the Supersonic Steam Ejector Use in Steam Turbine System

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Lin Cai ◽  
Miao He
Keyword(s):  
Steam Turbine ◽  
Numerical Study ◽  
Fluid Pressure ◽  
Ideal Gas ◽  
Entrainment Ratio ◽  
Real Gas ◽  
Steam Ejector ◽  
Mixing Chamber ◽  
Cfd Method ◽  
Ideal Gas Model

Supersonic steam ejector is widely used in steam energy systems such as refrigeration, wood drying equipment, papermaking machine, and steam turbine. In this paper the Computational Fluids Dynamics (CFD) method was employed to simulate a supersonic steam ejector, SST k-w turbulence model was adopted, and both real gas model and ideal gas model for fluid property were considered and compared. The mixing chamber angle, throat length, and nozzle exit position (NXP) primary pressure and temperature effects on entrainment ratio were investigated. The results show that performance of the ejector is underestimated using ideal gas model, and the entrainment ratio is 20%–40% lower than that when using real gas model. There is an optimum mixing chamber angel and NXP makes the entrainment ratio achieve its maximum; as throat length is decreased within a range, the entrainment ratio remains unchanged. Primary fluid pressure has a critical value, and the entrainment ratio reaches its peak at working critical pressure; when working steam superheat degree increases, the entrainment ratio is increased.

Micromixer: Alternative Passive Solution With Injection Amplificator System

2011 ◽  
Author(s):  
Brahim Dennai ◽  
Rachid Khelfaoui ◽  
A. hak Bentaleb ◽  
A. hak Maazouzi
Keyword(s):  
Numerical Study ◽  
Diffusion Flux ◽  
Characteristic Size ◽  
The Novel ◽  
Mixing Rate ◽  
Mixing Performance ◽  
Two Fluids ◽  
Mixing Chamber ◽  
Passive Mixing ◽  
Mixing Method

Mixing rate is characterized by the diffusion flux given by the Fick’s law. A passive mixing strategy is proposed to enhance mixing of two fluids through perturbed jet flow. A numerical study of passive mixers has been presented. This paper is focused on the modeling of a micro-injection systems composed of passive amplifier without mechanical part. The microsystem modeling is based on geometrical oscillators form. An asymmetric micro-oscillator design based on a monostable fluidic amplifier is proposed [2,7]. The characteristic size of the channels is generally about a few hundred of microns. The numerical results indicate that the mixing performance can be as high as 92% within a typical mixing chamber of 2.25 mm diameter and 0.20 mm length when the Reynolds number is Re = 490. In addition, the results confirm that self-rotation in the circular mixer significantly enhances the mixing performance. The novel micro mixing method presented in this study provides a simple solution to mixing problems in micro system.

Numerical study on the mixing quality of an electroosmotic micromixer under periodic potential

2020 ◽  
Vol 234 (11) ◽  
pp. 2113-2125 ◽  
Author(s):  
Habib Jalili ◽  
Mohammad Raad ◽  
Davoud Abbasinezhad Fallah
Keyword(s):  
Numerical Study ◽  
Phase Lag ◽  
Voltage Amplitude ◽  
Effective Parameters ◽  
Inlet Velocity ◽  
Low Reynolds Number Flows ◽  
Mixing Chamber ◽  
Mixing Quality ◽  
Reynolds Number Flows

Improvement of the mixing quality of low Reynolds number flows in micro-dimensional devices is essential. This paper investigates the optimization of the effective parameters and their effects on the mixing quality in a two-dimensional active micromixer. The micromixer mixes fluids with different concentrations entering into a microchannel from different inlets by means of four microelectrodes placed on the walls of a mixing chamber. A time-dependent electric field is applied, and the resulting electroosmotic force perturbs the parallel streamlines in the otherwise highly ordered laminar flow. The governing equations are numerically solved using the finite element-based COMSOL Multiphysics (Version 5.2a) software. The electroosmotic actuated active micromixer was numerically studied for various values of inlet velocity, phase lag, frequency, and voltage amplitude. Once the optimum values of the effective parameters are obtained for the original micromixer, they are applied to the micromixers having different obstacle shape inside the mixing chamber. The results showed that the mixing quality strongly depends on the inlet velocity of the fluids, the electrodes phase lag, the frequency, and the voltage amplitude. In addition, the mixing quality does not depend on obstacle shape when the optimum values of these parameters were used.

Heat transfer during spray/wall interaction with urea water solution: An experimental parameter study

2019 ◽  
Vol 78 ◽  
pp. 108432 ◽  
Author(s):  
David Schweigert ◽  
Björn Damson ◽  
Hartmut Lüders ◽  
Marion Börnhorst ◽  
Olaf Deutschmann
Keyword(s):  
Heat Transfer ◽  
Water Solution ◽  
Experimental Parameter ◽  
Parameter Study ◽  
Wall Interaction

Numerical Study of the Internal Flow Field Characteristics in Mixed Flow Turbines

2002 ◽  
Author(s):  
D. Palfreyman ◽  
R. F. Martinez-Botas
Keyword(s):  
Flow Field ◽  
Cell Density ◽  
Numerical Study ◽  
Internal Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Facility ◽  
Meridional Plane ◽  
Mixed Flow ◽  
Radial Turbine

Presented is a numerical investigation of the characteristics of the internal flow field of a high-speed low-pressure ratio mixed flow turbine of 95.14 mm tip diameter. A commercial computational fluid dynamics (CFD) code has been successfully employed. This has been carefully validated to experimental data taken from a turbine test facility at this institution. A comparison to gated (in phase with the turbine rotation) Laser Doppler Velocimetry measurements at the turbine trailing edge and total to static efficiencies at various operating conditions, was made showing good agreement. Details of the internal flow field from a numerical study using a 393,872 cell density model are presented. These details have been compared to a radial turbine of similar geometry and performance characteristics, also analyzed using the same cell density and analysis and boundary conditions. The flow field was found to be highly three-dimensional with the tip leakage vortex as the dominant secondary flow feature. The tip clearance flow was found to be significantly influenced by the relative motion of the shroud wall, which suppressed the development of a vortex within the mainstream passage particularly in the inducer region. Comparison to the radial turbine has shown noticeable differences concentrated in the inducer region where the greater Coriolis acceleration in the radial turbine is more influential in the development of secondary flows. Considerable loss is observed localized at the blade leading edge tip region along the full length of the blade pitch; this is associated with the increased streamline curvature in the meridional plane.

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