Influence of the Structure of Micro Premixing Chamber on the Uniformity of Flow Distribution and Premixing Characteristics

2011 ◽  
Author(s):  
Yunfei Yan ◽  
Li Zhang ◽  
Jingyu Ran ◽  
Jie Zhang
Keyword(s):  
Residence Time ◽  
Flow Distribution ◽  
Combustion Efficiency ◽  
Micro Channels ◽  
High Efficient ◽  
Micro Combustor

In micro combustors, the residence time of gas is dramatically reduced. It is much more important to improve combustion efficiency and stability of the micro-combustor by improving the uniformity of flow distribution and mixed results in micro premixing chamber. The flow distribution in micro premixing chamber is analyzed. The influence of micro premixing chamber structures (including the diameter of fuel inlet, numbers of arc-shaped and straight micro-channels, distance and numbers of subordinate fuel inlets) on the uniformity of flow distribution and premixing characteristics is numerical investigated. The influence of the different structure of micro premixing chamber is gained. It is an important guide for designing high efficient micro premixing devices.

scholarly journals Combustion and Deposition, Erosion, and Corrosion Tests of Coal Turbine Fuels

1985 ◽  
Author(s):  
C. Wilkes ◽  
R. Wenglarz ◽  
D. W. Clark
Keyword(s):  
Residence Time ◽  
Combustion Efficiency ◽  
Water Slurry ◽  
Lean Combustion ◽  
Coal Water Slurry ◽  
Unburned Hydrocarbons ◽  
Alternative Approaches ◽  
The Rich ◽  
Burning Coal ◽  
Distillate Fuel

This paper discusses the results obtained from the rich-quench-lean (RQL) combustion system running on distillate fuel and coal water slurry (CWS). Estimates of fuel bound nitrogen (FBN) yield indicate that rich lean combustion is successful in reducing the yield from coal water slurry fuel to between 8% and 12%. Some improvements in combustion efficiency are required when burning coal water slurry to reduce carbon monoxide and unburned hydrocarbons to acceptable levels. These improvements are achievable by increasing the lean zone residence time. Further testing is planned to investigate the effects of residence time in more detail. The planned deposition, erosion, and corrosion (DEC) testing will evaluate alternative approaches for protection from deposition, erosion, and corrosion of turbines operating with coal derived fuels.

Analysis of non-uniform flow distribution in parallel micro-channels

2019 ◽  
Vol 33 (8) ◽  
pp. 3859-3864 ◽  
Author(s):  
Jungchul Kim ◽  
Jeong Heon Shin ◽  
Sangho Sohn ◽  
Seok Ho Yoon
Keyword(s):  
Flow Distribution ◽  
Uniform Flow ◽  
Micro Channels ◽  
Uniform Flow Distribution

Numerical and Experimental Study on Soot Accumulation on the Wall of Falling Fuel Film Micro-Combustor

2010 ◽  
Author(s):  
Ning Mei ◽  
Xiaoyan Wang ◽  
Hongming Zhao ◽  
Yan Li ◽  
Hongyu Si
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
Complex Structure ◽  
Flow Distribution ◽  
Experimental Results ◽  
Fuel Film ◽  
Numerical Result ◽  
Different Diameters ◽  
Micro Combustor

Fluid flow contributes much to fuel-air mixture formation in a micro-combustor, the RNG k-ε turbulence model was used to simulate the cold flow field of a falling fuel film microcombustor, and comparison was made between numerical result and experimental results. It is shown that the RNG k-ε turbulence model translated the flow field of a complex structure micro-combustor and the soot accumulation on the wall of combustion chamber. The experimental results showed that soot accumulation occurs in vortex backflow area near the wall of combustion chamber and the numerical methods is helpful for understanding the way of soot accumulation in the wall of combustion chamber. Therefore, modifications on the flow field with different diameters and entrance direction of the air flow into the primary combustion chamber were made. The numerical simulation of flow distribution showed that the flow field of micro-combustor could be ideal for eliminated soot accumulation.

Effect of Manifold Design on Flow Distribution in Parallel Micro-Channels

2003 ◽  
Author(s):  
Ralph L. Webb
Keyword(s):  
Flow Distribution ◽  
Reynolds Numbers ◽  
Published Data ◽  
Micro Electro Mechanical Systems ◽  
Micro Channels ◽  
Significant Disagreement ◽  
Manufacturing Tolerances ◽  
Header Design ◽  
Laminar And Turbulent Regimes ◽  
Good Agreement

Gas or liquid flow in multiple, parallel micro-channels is of interest for Micro-Electro-Mechanical Systems (MEMS) cooling applications. The published data for friction in 10-to-400μm hydraulic diameter, single micro-channels show good agreement with the conventional equations in the laminar and turbulent regimes. However, investigators of flow in multiple, parallel micro-channels in the same range of channel sizes report significantly different results. They report significant disagreement with the conventional equations and argue that transition occurs at Reynolds numbers as small as 200, dependent on the channel shape. This paper proposes that the apparent discrepancies of friction in multiple micro-channels can be attributed to flow mal-distribution. Flow mal-distribution is expected in multi-channels, because of manufacturing tolerances and poor manifold design. It can be minimized by proper header design and better manufacturing tolerances.

A Practical Solid-Propellant Micro-Thruster

2006 ◽  
Author(s):  
E. A. Parra ◽  
K. S. J. Pister ◽  
C. Fernandez-Pello
Keyword(s):  
Residence Time ◽  
Solid Propellant ◽  
Volume Ratio ◽  
Combustion Efficiency ◽  
Macro Scale ◽  
Aerospace Systems ◽  
Composite Solid Propellant ◽  
Active Research ◽  
Micro Propulsion ◽  
Composite Solid

Miniaturization of solid-propellant thrusters is an area of active research that has been motivated by the reduction in size of aerospace systems and the advancement of micromachining techniques. Though this micro-propulsion problem seems simplistic compared to the macro-scale counterpart, an efficient and reliable device has yet to be produced. A millimeter-scale novel composite solid-propellant thruster design that builds on pervious work [1] and increases efficiency is here presented. Current designs made primarily out of silicon suffer from high thermal losses and, in extreme cases, flame quenching due to the augmented surface area to volume ratio associated with miniaturization. Moreover, the reduced device dimensions drive the combustion reaction to complete outside of the thruster, misemploying the majority of the chemical energy. This occurs because the propellant mixing and chemical time do not scale with size, while the residence time does decrease as the size of the thruster decreases [2]. A novel thruster design that increases the propellant residence time is being characterized using ammonium perchlorate/binder composite propellant. The thruster geometry recycles thermal energy to the unburned propellant grain increasing its temperature and, therefore, burning rate and combustion efficiency. In addition, propellant formulation has been optimized for the thruster minimization.

NUMERICAL STUDY OF THE EFFECT OF AREA OF MANIFOLD AND INLET/OUTLET FLOW ARRANGEMENT 0N FLOW DISTRIBUTION IN PARALLEL RECTANGULAR MICROCHANNEL COOLING SYSTEM

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Amirah M. Sahar ◽  
A. I. M. Shaiful
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Cooling System ◽  
Numerical Study ◽  
Flow Distribution ◽  
Fluid Temperature ◽  
Rectangular Microchannel ◽  
Temperature Distributions ◽  
Micro Channels ◽  
Parallel Microchannels

Parallel microchannels have been widely used in cooling of compact electronic equipment due to large contact area with liquid and availability of large mass of fluid to carry away heat. However, understanding of flow distribution for microchannel parallel system is still unclear and there still lack of studies give a clear pictures to understand the complex flow features which cause the flow maldistribution. Generally, the geometrical structure of the manifold and micro channels play an important role in flow distribution between micro channels, which might affects the heat and mass transfer efficiency, even the performance of micro exchangers. A practical design of exchanger basically involves the selection of an optimized solution, keeping an optimal balance between gain in heat transfer and pressure drop penalty. A parallel microchannels configurations consisting inlet and outlet rectangular manifold were simulated to study flow distribution among the channels were investigated numerically by using Ansys Fluent 14.5. The numerical results was validated using existing experimental data and showed a similar trend with values 1% higher than experimental data. The influence of inlet/outlet manifold area and inlet/outlet arrangement on flow distribution in channels were carried out in this study. Based on the predicted flow non-uniformity value, 𝜙, Z- type flow arrangement exhibits higher value of 𝜙, which is 8%, followed by U-type, 2.6% and the I-type, 2.49%. Thus, a better uniformity of velocity and temperature distributions can be achieved in I-shape flow arrangement. The behavior of the flow distributions inside channels is due to the vortices that occurred at manifold. Besides comparing the pressure drop for case 1(D1) and case 2(D2), it is worth to mention that, as the area of inlet and outlet manifold decrease by 50%, the pressure drop is increasing about 5%. However, the inlet/outlet area of manifold on velocity and fluid temperature distributions was insignificant.

scholarly journals A Novel Catalytic Micro-Combustor Inspired by the Nasal Geometry of Reindeer: CFD Modeling and Simulation

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 606
Author(s):  
Valeria Di Sarli ◽  
Marco Trofa ◽  
Almerinda Di Benedetto
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Residence Time ◽  
Convective Heat Transfer Coefficient ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Micro Combustor

A three-dimensional CFD model of a novel configuration of catalytic micro-combustor inspired by the nasal geometry of reindeer was developed using the commercial code ANSYS Fluent 19.0. The thermal behavior of this nature-inspired (NI) configuration was investigated through simulations of lean propane/air combustion performed at different values of residence time (i.e., inlet gas velocity) and (external convective) heat transfer coefficient. Simulations at the same conditions were also run for a standard parallel-channel (PC) configuration of equivalent dimensions. Numerical results show that the operating window of stable combustion is wider in the case of the NI configuration. In particular, the blow-out behavior is substantially the same for the two configurations. Conversely, the extinction behavior, which is dominated by competition between the heat losses towards the external environment and the heat produced by combustion, differs. The NI configuration exhibits a greater ability than the PC configuration to keep the heat generated by combustion trapped inside the micro-reactor. As a consequence, extinction occurs at higher values of residence time and heat transfer coefficient for this novel configuration.

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