scholarly journals Modeling of Twofold Flame Behavior of Ceramic Foam Surface Burners

1995 ◽  
Vol 117 (1) ◽  
pp. 29-36
Author(s):  
P. F. J. Severens ◽  
P. H. Bouma ◽  
C. J. H. van de Ven ◽  
L. P. H. de Goey ◽  
A. van der Drift
Keyword(s):  
Pressure Drop ◽  
Transport Phenomena ◽  
Ceramic Foam ◽  
Gas Velocity ◽  
One Dimensional ◽  
Gas Burner ◽  
Global Pressure ◽  
Flame Behavior

A model for the flame behavior of a ceramic foam surface gas burner is developed. The burner plate is divided into small segments. Each segment is assumed to behave independently and the transport phenomena in each segment are assumed to be one-dimensional. Relations between the local gas velocity and global pressure drop are derived. The model predicts the pressure drop over the hot burner plate and the radiating fraction of the plate reasonably well.

Selective Catalytic Reduction of NOx over Zeolite-Coated Cordierite-Based Ceramic Foams: Water Deactivation

2008 ◽  
Vol 587-588 ◽  
pp. 810-814 ◽  
Author(s):  
Susana Dias ◽  
Fernando A. Costa Oliveira ◽  
C. Henriques ◽  
F.R. Ribeiro ◽  
Carmen M. Rangel ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Early Stage ◽  
Low Pressure ◽  
Membrane Reactors ◽  
Ceramic Foam ◽  
Catalytic Distillation ◽  
Ceramic Foams ◽  
Stage Of Development

The reactors used for Selective Catalytic Reduction (SCR) of NOx require low pressure drop structured catalyst packing. Structured packings, such as ceramic foams, are gaining increasing interest for application in low pressure drop reactors, membrane reactors and catalytic distillation units. In this work, cobalt ion exchanged mordenite (Co-HMOR)-coated cordierite-based foams produced by the replication method were evaluated for catalytic reduction of NOx with methane. The addition of 0.3 wt.% Pd to 2 wt.% Co-HMOR leads to a material that can convert 50 % NOx to N2 at 450 °C in a reaction mixture containing 2000 ppm CH4, 1000 ppm NOx, 5 % O2 and balance helium, at GHSV=17000 h-1. Although in an early stage of development, an efficient coating procedure was explored and different ways of exchange of Co and Pd cations into mordenite (Si/Al=10) were studied. Additions of 2 wt.% fumed silica enhanced adhesion of the zeolite onto the ceramic foam. Pd-exchanged Co-HMOR showed to be very sensitive to steam. A 50 % decrease in NOx conversion to N2 was observed after Pd/Co-HMOR samples were exposed at 450 °C to a reaction mixture containing 2 vol% H2O. Although further research is needed to ascertain the mechanism of this deactivation behaviour, agglomeration of Pd forming PdO particles is envisaged.

scholarly journals Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

One-dimensional transport phenomena in GaAs heterojunction structures

1990 ◽  
Vol 168 (1) ◽  
pp. 112-120
Author(s):  
M. Pepper ◽  
R.J. Brown ◽  
C.G. Smith ◽  
D.A. Wharam ◽  
M.J. Kelly ◽  
...  
Keyword(s):  
Transport Phenomena ◽  
One Dimensional

scholarly journals The Effect of Very Cohesive Ultra-Fine Particles in Mixtures on Compression, Consolidation, and Fluidization

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 439
Author(s):  
Abbas Kamranian Marnani ◽  
Andreas Bück ◽  
Sergiy Antonyuk ◽  
Berend van Wachem ◽  
Dominique Thévenin ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Binary Mixture ◽  
Packing Density ◽  
Fine Particles ◽  
Bulk Material ◽  
Applied Pressure ◽  
Gas Velocity ◽  
History Effect ◽  
Ultra Fine Particles ◽  
Linear Manner

This paper focuses on the effect of ultra-fine ( d < 10 µm) powders in mixtures with fine ( d < 100 µm) bulk material on compression processes and also evaluates the re-fluidization behavior of the compressed bed (history effect). Achieving this goal, different mixtures of fine and ultra-fine Ground-Carbonate-Calcium were compressed at three pressure levels. The results show that by increasing the applied pressure, the compressibility decreases due to change in compaction regime. Subsequently, for the higher pressure, the slope of packing density versus applied stress curves is noticeably different. However, this slope does not depend on the size distribution of mixtures, but on the type of material. Comparing fluidization and re-fluidization curves (bed pressure drop vs. gas velocity) shows an increase in the maximum bed pressure drop ( Δ P p e a k ) for re-fluidization. By increasing the portion of ultra-fine particles in the binary mixture, Δ P p e a k increases in a non-linear manner. Furthermore, the incipient fluidization point moves to a higher gas velocity. After compression, the peak of the bed pressure drop in the re-fluidization test happens at a lower gas velocity than in the initial fluidization test. Thus, the slope of the loading curve is much larger for re-fluidization. The opposite is observed for the unloading curves.

Study of the pressure drop in dust scrubber affected by liquid flowability

2019 ◽  
Vol 233 (5) ◽  
pp. 1066-1073 ◽  
Author(s):  
Xiaochuan Li ◽  
Tao Wei ◽  
Xinhao Xu ◽  
Reyna M Knight ◽  
Jiahang Li
Keyword(s):  
Pressure Drop ◽  
Drag Coefficient ◽  
Linear Relationship ◽  
Gas Phase ◽  
Force Balance ◽  
Liquid Level ◽  
Gas Velocity ◽  
Two Phase ◽  
Total Drag ◽  
Quadratic Curve

The complexity of the gas-liquid two-phase flow results in equally complicated pressure drop characteristics for self-excited wet dust scrubbers. In this paper, the pressure drop of the dust scrubber was studied by measuring the total pressure drop R and the differential liquid level Δ H versus the gas velocity v at different initial liquid level b0 values, combined with the liquid flowability. The results showed that the dust scrubber varied its total drag coefficient by changing the differential liquid level Δ H of the liquid-phase and then adjusting the gas-liquid two-phase force balance ahead of and behind the choke. Under the influence of liquid flowability, the throttling strength α exhibited a linear relationship with the gas velocity of the dust scrubber when b0 ≤ 0 mm. The Δ H-v and R- v characteristics of the dust scrubber varied with different values of b0 and v. When b0 > 0, the Δ H-v curve and R- v curve exhibited an explicit quadratic curve relationship. When b0 ≤ 0 mm, the Δ H-v curve and R- v curve exhibited an explicit linear relationship, where the Δ H-v curves can be expressed by a linear equation Δ H = khv+Δ H0, and the gas-phase pressure drop R can be approximately calculated using the differential liquid level Δ H. The liquid flowability can change the choke-sectional to change the total drag coefficient, which reduced in multiple folds with an increase in the gas velocity.

Discussion on the pressure drop calculation for oil‐water separated flow using a one dimensional two‐fluid model

2019 ◽  
Vol 97 (12) ◽  
pp. 3156-3174
Author(s):  
Nannan Liu ◽  
Wei Wang ◽  
Yingying Liu ◽  
Liang Ma ◽  
Jing Gong
Keyword(s):  
Pressure Drop ◽  
Fluid Model ◽  
Separated Flow ◽  
One Dimensional ◽  
Oil Water ◽  
Two Fluid Model ◽  
Two Fluid

Computation of flow and heat transfer in horizontal gas–solid flows through an adiabatic pipe

2020 ◽  
pp. 095440622093631
Author(s):  
Brundaban Patro ◽  
Kiran K Kupireddi ◽  
Jaya K Devanuri
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Solid Loading ◽  
Gas Velocity ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Loading Ratio ◽  
Solid Temperature

The current paper deals with the studies of heat transfer and pressure drop through a horizontal, adiabatic pipe, having gas–solid flows. The inlet air temperature is 443 K, whereas the inlet solid temperature is 308 K. The numerical results are compared with the benchmark experimental data and are agreed satisfactorily. The influences of solid loading ratio, solid diameter and gas velocity on Nusselt number and pressure drop have been studied. The Nusselt number decreases and the pressure drop increases with an increase in the solid diameter. The Nusselt number decreases with an increase in the solid loading ratio at a lower solid diameter of 100 µm. However, at a higher value of solid diameter of 200 µm, the Nusselt number first decreases up to a specific solid loading ratio, and after that, it increases. The pressure drop results show different behaviours with the solid loading ratio. Both the Nusselt number and pressure drop increase with the gas velocity. Finally, a correlation is generated to calculate the two-phase Nusselt number.

Properties of ceramic foam catalyst supports: pressure drop

2000 ◽  
Vol 204 (1) ◽  
pp. 19-32 ◽  
Author(s):  
J.T Richardson ◽  
Y Peng ◽  
D Remue
Keyword(s):  
Pressure Drop ◽  
Ceramic Foam ◽  
Catalyst Supports

Theoretical Model of a Flow in a Tube With a Slit

2019 ◽  
Author(s):  
Yuki Toda ◽  
Masataka Morimatsu ◽  
Yu Nishio ◽  
Takanobu Ogawa
Keyword(s):  
Theoretical Model ◽  
Flow Field ◽  
Pressure Loss ◽  
Longitudinal Direction ◽  
Gas Mixture ◽  
Straight Tube ◽  
One Dimensional ◽  
Tube Type ◽  
Gas Burner

Abstract A tube-type gas burner consists of a straight tube with a slit along it and discharges an air-gas mixture through the slit to produce a flame. The flow velocity from the slit depends on the pressure in the tube and the pressure loss at the slit, and it varies in the longitudinal direction of the tube. The resulting uneven flame degrades the quality of the burner. In this study, we develop a one-dimensional theoretical model of the flow in a tube with a slit. To validate the result of the theoretical model, we also conduct experiments and numerical simulations for the same flow field. We applied this theoretical model to a flow in a tube, 1 m length, 40 mm in diameter, with a slit 2.5 mm wide. The end of the tube is closed. We also discuss the effect of the length of the burner on the unevenness.

One-Dimensional Models of the Human Biliary System

2006 ◽  
Vol 129 (2) ◽  
pp. 164-173 ◽  
Author(s):  
W. G. Li ◽  
X. Y. Luo ◽  
A. G. Johnson ◽  
N. A. Hill ◽  
N. Bird ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Cystic Duct ◽  
Biliary System ◽  
Maximum Pressure ◽  
Equivalent Diameter ◽  
Excessive Pressure ◽  
Subsequent Formation ◽  
One Dimensional ◽  
Normal Human ◽  
Dimensional Models

This paper studies two one-dimensional models to estimate the pressure drop in the normal human biliary system for Reynolds number up to 20. Excessive pressure drop during bile emptying and refilling may result in incomplete bile emptying, leading to stasis and subsequent formation of gallbladder stones. The models were developed following the group’s previous work on the cystic duct using numerical simulations. Using these models, the effects of the biliary system geometry, elastic property of the cystic duct, and bile viscosity on the pressure drop can be studied more efficiently than with full numerical approaches. It was found that the maximum pressure drop occurs during bile emptying immediately after a meal, and is greatly influenced by the viscosity of the bile and the geometric configuration of the cystic duct, i.e., patients with more viscous bile or with a cystic duct containing more baffles or a longer length, have the greatest pressure drop. It is found that the most significant parameter is the diameter of the cystic duct; a 1% decrease in the diameter increases the pressure drop by up to 4.3%. The effects of the baffle height ratio and number of baffles on the pressure drop are reflected in the fact that these effectively change the equivalent diameter and length of the cystic duct. The effect of the Young’s modulus on the pressure drop is important only if it is lower than 400Pa; above this value, a rigid-walled model gives a good estimate of the pressure drop in the system for the parameters studied.

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