A comparative numerical study of the combustion performance of the syngas-fueled HCCI engine using a toroidal piston, square bowl piston, and flat piston shape at different loads

2021 ◽  
pp. 1-27
Author(s):  
Kabbir Ali ◽  
Changup Kim ◽  
Yonggyu Lee ◽  
Seungmook Oh ◽  
Ki-Seong Kim
Keyword(s):  
Numerical Study ◽  
Pressure Rise ◽  
Fuel Mixture ◽  
Combustion Efficiency ◽  
Maximum Pressure ◽  
Cross Sectional ◽  
Combustion Performance ◽  
Hcci Engine ◽  
Heat Loss Rate ◽  
Piston Bowl

Abstract This study analyzes the combustion performance of a syngas-fueled homogenous charge compression ignition (HCCI) engine using a toroidal piston, square bowl, and flat piston shape, at low, medium, and high loads, with a constant compression ratio of 17.1. In this study, the square bowl shape is optimized by reducing the piston bowl depth and squish area ratio (squish area/cylinder cross-sectional area) from (34 to 20, 10, and 2.5) %, and compared with the flat piston shape and toroidal piston shape. This HCCI engine operates under an overly lean air–fuel mixture condition for power plant usage. ANSYS Forte CFD with GRI Mech3.0 chemical kinetics is used for combustion analysis, and the calculated results are validated by the experimental results. All simulations are accomplished at maximum brake torque (MBT) by altering the air–fuel mixture temperature at IVC with a constant equivalence ratio of 0.27. This study reveals that the main factors that affect the start of combustion , maximum pressure rise rate (MPRR), combustion efficiency, and thermal efficiency by changing the piston shape are the squish flow and reverse squish flow effects. Therefore, the square bowl piston D is the optimized piston shape that offers low MPRR and high combustion performance for the syngas-fueled HCCI engine, due to the weak squish flow and low heat loss rate through the combustion chamber wall, respectively, compared to the other piston shapes of square bowl piston A, B, and C, flat piston, and toroidal (baseline) piston shape.

A Numerical Study to Control the Combustion Performance of a Syngas-Fueled HCCI Engine at Medium and High Loads Using Different Piston Bowl Geometry and Exhaust Gas Recirculation

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Kabbir Ali ◽  
Changup Kim ◽  
Yonggyu Lee ◽  
Seungmook Oh ◽  
Kiseong Kim
Keyword(s):  
Numerical Study ◽  
Combustion Process ◽  
Pressure Rise ◽  
Fuel Mixture ◽  
Exhaust Gas Recirculation ◽  
Maximum Pressure ◽  
Exhaust Gas ◽  
Hcci Engine ◽  
Piston Bowl ◽  
Gas Recirculation

Abstract This study aims to analyze the effect of piston bowl geometry on the combustion and emission performance of the syngas-fueled homogenous charge compression ignition (HCCI) engine, which operates under lean air–fuel mixture conditions for power plant usage. Three different piston bowl geometries were used with a reduction of piston bowl depth and squish area ratio of the baseline piston bowl with the same compression ratio of 17.1. Additionally, exhaust gas recirculation (EGR) is used to control the maximum pressure rise rate (MPRR) of syngas-fueled HCCI engines. To simulate the combustion process at medium load (5 bar indicated mean effective pressure (IMEP)) and high loads of (8 and 10 bar IMEP), ansys forte cfd package was used, and the calculated results were compared with Aceves et al.’s Multi-zone HCCI model, using the same chemical kinetics set (Gri-Mech 3.0). All calculations were accomplished at maximum brake torque (MBT) conditions, by sweeping the air–fuel mixture temperature at the inlet valve close (TIVC). This study reveals that the TIVC of the air–fuel mixture and the heat loss rate through the wall are the main factors that influence combustion phasing by changing the piston bowl geometry. It also finds that although pistons B and C give high thermal efficiency, they cannot be used for the combustion process, due to the very high MPRR and NOx emissions. Even though the baseline piston shows high MPRR (23 bar/degree), it is reduced, and reveals an acceptable range of 10–12 bar/degree, using 30% EGR.

Numerical Study of Spray Parametric Effects on Gas Turbine Combustion Performance

1999 ◽  
Author(s):  
K. Su ◽  
C. Q. Zhou
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Numerical Study ◽  
Combustion Efficiency ◽  
Fuel Spray ◽  
Injection Velocity ◽  
Fuel Sprays ◽  
Combustion Performance ◽  
Mean Diameter ◽  
Spray Distribution

Abstract A numerical study was conducted to determine the effects of fuel spray characteristics on the gas turbine combustion performance including the combustion efficiency and the overall temperature distribution factor (OTDF) at the exit of the combustor using the KIVA-3V code. A model of a typical annular combustor was used in the computations. Operating conditions were varied with inlet pressure from 0.1 to 1.2 MPa, inlet temperature from 400 to 650 K, and air fuel ratio from 0.015 to 0.024. A log-normal spray distribution was assumed to simulate a real fuel spray distribution at injection. The droplet mean diameter as well as injection velocity and angle were independently varied to distinguish the separate effects of variables involved. Flow fields and temperature distributions in the combustor were analyzed. The results reasonably agreed with those from a semi-empirical approach. It is found that the overall temperature distribution deteriorates as the Sauter mean diameter of fuel spray increases. There is an optimum range of the Sauter mean diameters for the efficient combustion of fuel sprays. The overall temperature distribution is improved as the injection velocity of fuel sprays increases, but the combustion efficiency does not change much with it. It appears that the KIVA-3V code can be used to guide the design and improvement of the gas turbine combustor.

A Numerical Study to Investigate the Effect of Syngas Composition and Compression Ratio on the Combustion and Emission Characteristics of a Syngas-Fueled HCCI Engine

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Kabbir Ali ◽  
Changup Kim ◽  
Yonggyu Lee ◽  
Seungmook Oh ◽  
Kiseong Kim
Keyword(s):  
Compression Ratio ◽  
Consumption Rate ◽  
Volume Fraction ◽  
Numerical Study ◽  
Load Condition ◽  
Fuel Mixture ◽  
Peak Temperature ◽  
Dominant Factor ◽  
Temperature Range ◽  
Hcci Engine

Abstract The purpose of this work is to investigate syngas composition (of constituents H2, CO, and CO2) and compression ratio (CR) effects on the combustion and emissions characteristics of a syngas-fueled homogenous charge compression ignition (HCCI) engine, which operates in very lean air–fuel mixture conditions for power plant usage. Investigations were conducted using ansys forte cfd package at low (3 bar indicated mean effective pressure (IMEP)) and medium (5 bar IMEP) loads, and the calculated results were compared with the Aceves et al.’s multi-zone HCCI model, using the same chemical kinetics set (Gas Research Institute (GRI)-Mech3.0). All calculations were carried out at maximum brake torque (MBT) conditions by sweeping the air–fuel mixture temperature at intake valve closing (IVC) (TIVC).This study found out that the H2 consumption rate is slightly high in a low-temperature range in the early period of combustion while the CO consumption rate is high in a high-temperature range in the later period of combustion. The results reveal that the change of H2 /CO ratio and inert gas volume fraction according to fuel composition affects combustion, but the TIVC is the dominant factor affecting combustion phasing at MBT conditions. For each fuel and load condition, the TIVC was significantly reduced with the increase of CR (17.1–22.3) to get MBT conditions, which causes to retard combustion phasing and lowers in-cylinder peak temperature. The oxides of nitrogen (NOx) emissions reduced with increasing the CR due to the lowering of the in-cylinder peak temperature.

Effect of Chemical Hythane Composition on Pressure in Combustion Chamber of Engine

2019 ◽  
pp. 36-42
Author(s):  
A. P. Shaikin ◽  
I. R. Galiev
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Power Plants ◽  
Engine Speed ◽  
Combustion Engine ◽  
Fuel Mixture ◽  
Maximum Pressure ◽  
Chamber Volume ◽  
Excess Air ◽  
Scientific Papers

The article analyzes the influence of chemical composition of hythane (a mixture of natural gas with hydrogen) on pressure in an engine combustion chamber. A review of the literature has showed the relevance of using hythane in transport energy industry, and also revealed a number of scientific papers devoted to studying the effect of hythane on environmental and traction-dynamic characteristics of the engine. We have studied a single-cylinder spark-ignited internal combustion engine. In the experiments, the varying factors are: engine speed (600 and 900 min-1), excess air ratio and hydrogen concentration in natural gas which are 29, 47 and 58% (volume).The article shows that at idling engine speed maximum pressure in combustion chamber depends on excess air ratio and proportion hydrogen in the air-fuel mixture – the poorer air-fuel mixture and greater addition of hydrogen is, the more intense pressure increases. The positive effect of hydrogen on pressure is explained by the fact that addition of hydrogen contributes to increase in heat of combustion fuel and rate propagation of the flame. As a result, during combustion, more heat is released, and the fuel itself burns in a smaller volume. Thus, the addition of hydrogen can ensure stable combustion of a lean air-fuel mixture without loss of engine power. Moreover, the article shows that, despite the change in engine speed, addition of hydrogen, excess air ratio, type of fuel (natural gas and gasoline), there is a power-law dependence of the maximum pressure in engine cylinder on combustion chamber volume. Processing and analysis of the results of the foreign and domestic researchers have showed that patterns we discovered are applicable to engines of different designs, operating at different speeds and using different hydrocarbon fuels. The results research presented allow us to reduce the time and material costs when creating new power plants using hythane and meeting modern requirements for power, economy and toxicity.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

Vibration analysis and combustion parameter evaluation of CI engine based on Fourier Decomposition Method

2021 ◽  
pp. 146808742098819
Author(s):  
Wang Yang ◽  
Cheng Yong
Keyword(s):  
Vibration Analysis ◽  
Decomposition Method ◽  
Combustion Process ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Vibration Signals ◽  
Loop Control ◽  
Fourier Decomposition ◽  
Surface Vibration ◽  
Rise Rate

As a non-intrusive method for engine working condition detection, the engine surface vibration contains rich information about the combustion process and has great potential for the closed-loop control of engines. However, the measured engine surface vibration signals are usually induced by combustion as well as non-combustion excitations and are difficult to be utilized directly. To evaluate some combustion parameters from engine surface vibration, the tests were carried out on a single-cylinder diesel engine and a new method called Fourier Decomposition Method (FDM) was used to extract combustion induced vibration. Simulated and test results verified the ability of the FDM for engine vibration analysis. Based on the extracted vibration signals, the methods for identifying start of combustion, location of maximum pressure rise rate, and location of peak pressure were proposed. The cycle-by-cycle analysis of the results show that the parameters identified based on vibration and in-cylinder pressure have the similar trends, and it suggests that the proposed FDM-based methods can be used for extracting combustion induced vibrations and identifying the combustion parameters.

Numerical investigations on the effect of volute casing treatment for performance augmentation in a centrifugal fan

2021 ◽  
pp. 095440622110341
Author(s):  
Manjunath L Nilugal ◽  
K Vasudeva Karanth ◽  
Madhwesh N
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Centrifugal Fan ◽  
Casing Treatment ◽  
Sliding Mesh ◽  
Optimum Configuration

This article presents the effect of volute chamfering on the performance of a forward swept centrifugal fan. The numerical analysis is performed to obtain the performance parameters such as static pressure rise coefficient and total pressure coefficient for various flow coefficients. The chamfer ratio for the volute is optimized parametrically by providing a chamfer on either side of the volute. The influence of the chamfer ratio on the three dimensional flow domain was investigated numerically. The simulation is carried out using Re-Normalisation Group (RNG) k-[Formula: see text] turbulence model. The transient simulation of the fan system is done using standard sliding mesh method available in Fluent. It is found from the analysis that, configuration with chamfer ratio of 4.4 is found be the optimum configuration in terms of better performance characteristics. On an average, this optimum configuration provides improvement of about 6.3% in static pressure rise coefficient when compared to the base model. This optimized chamfer configuration also gives a higher total pressure coefficient of about 3% validating the augmentation in static pressure rise coefficient with respect to the base model. Hence, this numerical study establishes the effectiveness of optimally providing volute chamfer on the overall performance improvement of forward bladed centrifugal fan.

Study of Correctly Expanded Sonic Jet with Air Tabs

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Arun Prasad R ◽  
Thanigaiarasu S ◽  
Sembaruthi M ◽  
Rathakrishnan E
Keyword(s):  
Numerical Study ◽  
Cross Sectional ◽  
Potential Core ◽  
Convergent Nozzle ◽  
Jet Mixing ◽  
Pressure Profiles ◽  
Constant Diameter ◽  
Sonic Jet ◽  
Sectional Shape ◽  
Length Reduction

AbstractThe present numerical study is to understand the effect of air tabs located at the exit of a convergent nozzle on the spreading and mixing characteristics of correctly expanded sonic primary jet. Air tabs used in this study are two secondary jets issuing from constant diameter tubes located diametrically opposite at the periphery of the primary nozzle exit, normal to the primary jet. Two air tabs of Mach numbers 1.0 to 1.4, in steps of 0.1 are considered in this study. The mixing modification caused by air tabs are analysed by considering the mixing of uncontrolled (free) primary jet as a reference. Substantial enhancement in jet mixing is achieved with Mach 1.4 air tabs, which results in 80 % potential core length reduction. The total pressure profiles taken on the plane (YZ) normal to the primary jet axis, at various locations along the primary jet centreline revealed the modification of the jet cross sectional shape by air tabs. The stream-wise vortices and bifurcation of the primary jet caused by air tabs are found to be the mechanism behind the enhanced jet mixing.

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