Development of a Postprocessing Methodology for Studying Thermal Stratification in an HCCI Engine

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Benjamin Lawler ◽  
Mark Hoffman ◽  
Zoran Filipi ◽  
Orgun Güralp ◽  
Paul Najt
Keyword(s):  
Mass Fraction ◽  
Thermal Stratification ◽  
Reaction Rates ◽  
Combustion Efficiency ◽  
Temperature Fields ◽  
Coolant Temperature ◽  
Analysis Tool ◽  
Gas Temperature ◽  
Hcci Engine ◽  
Mass Distributions

Naturally occurring thermal stratification significantly impacts the characteristics of homogeneous charge compression ignition (HCCI) combustion. The in-cylinder gas temperature distributions prior to combustion dictate the ignition phasing, burn rates, combustion efficiency, and unburned hydrocarbon and CO emissions associated with HCCI operation. Characterizing the gas temperature fields in an HCCI engine and correlating them to HCCI burn rates is a prerequisite for developing strategies to expand the HCCI operating range. To study the development of thermal stratification in more detail, a new analysis methodology for postprocessing experimental HCCI engine data is proposed. This analysis tool uses the autoignition integral in the context of the mass fraction burned curve to infer information about the distribution of temperature that exists in the cylinder prior to combustion. An assumption is made about the shape of the charge temperature profiles of the unburned gas during compression and after combustion starts elsewhere in the cylinder. Second, it is assumed that chemical reaction rates proceed very rapidly in comparison to the staggering of ignition phasing from thermal stratification. The autoignition integral is then coupled to the mass fraction burned curve to produce temperature-mass distributions that are representative of a particular combustion event. Due to the computational efficiency associated with this zero-dimensional calculation, a large number of zones can be simulated at very little computational expense. The temperature-mass distributions are then studied over a coolant temperature sweep. The results show that very small changes to compression heat transfer can shift the distribution of mass and temperature in the cylinder enough to significantly affect HCCI burn rates and emissions.

Development of a Post-Processing Methodology for Studying Thermal Stratification in an HCCI Engine

2012 ◽  
Author(s):  
Benjamin Lawler ◽  
Mark Hoffman ◽  
Zoran Filipi ◽  
Orgun Güralp ◽  
Paul Najt
Keyword(s):  
Mass Fraction ◽  
Thermal Stratification ◽  
Reaction Rates ◽  
Temperature Fields ◽  
Coolant Temperature ◽  
Analysis Tool ◽  
Gas Temperature ◽  
Post Processing ◽  
Hcci Engine ◽  
Mass Distributions

Naturally occurring thermal stratification significantly impacts the characteristics of HCCI combustion. The in-cylinder gas temperature distributions prior to combustion dictate the ignition phasing, burn rates, combustion efficiency, and unburned hydrocarbon and CO emissions associated with HCCI operation. Characterizing the gas temperature fields in an HCCI engine and correlating them to HCCI burn rates is a prerequisite for developing strategies to expand the HCCI operating range. To study the development of thermal stratification in more detail, a new analysis methodology for post-processing experimental HCCI engine data is proposed. This analysis tool uses the autoignition integral in the context of the mass fraction burned curve to infer information about the distribution of temperature that exists in the cylinder prior to combustion. An assumption is made about the shape of the charge temperature profiles of the unburned gas during compression and after combustion starts elsewhere in the cylinder. Secondly, it is assumed that chemical reaction rates proceed very rapidly in comparison to the staggering of ignition phasing from thermal stratification. The autoignition integral is then coupled to the mass fraction burned curve to produce temperature-mass distributions that are representative of a particular combustion event. Due to the computational efficiency associated with this zero-dimensional calculation, a large number of zones can be simulated at very little computational expense. The temperature-mass distributions are then studied over a coolant temperature sweep. The results show that very small changes to compression heat transfer can shift the distribution of mass and temperature in the cylinder enough to significantly affect HCCI burn rates and emissions.

Understanding the Effect of Wall Conditions and Engine Geometry on Thermal Stratification and HCCI Combustion

2014 ◽  
Author(s):  
Benjamin Lawler ◽  
Satyum Joshi ◽  
Joshua Lacey ◽  
Orgun Guralp ◽  
Paul Najt ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Heat Release ◽  
Wall Temperature ◽  
Compression Ratio ◽  
Thermal Stratification ◽  
Ceramic Coatings ◽  
Combustion Efficiency ◽  
Noticeable Effect ◽  
Hcci Engine ◽  
Hcci Combustion

Thermal stratification of the unburned charge in the cylinder has a profound effect on the burn characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine. Experimental data was collected in a single cylinder, gasoline-fueled, HCCI engine in order to determine the effects of combustion chamber geometry and wall conditions on thermal stratification and HCCI combustion. The study includes a wall temperature sweep and variations of piston top surface material, piston top geometry, and compression ratio. The data is processed with a traditional heat release routine, as well as a post-processing tool termed the Thermal Stratification Analysis, which calculates an unburned temperature distribution from heat release. For all of the sweeps, the 50% burned point was kept constant by varying the intake temperature. Keeping the combustion phasing constant ensures the separation of the effects of combustion phasing from the effects of wall conditions alone on HCCI and thermal stratification. The results for the wall temperature sweep show no changes to the burn characteristics once the combustion phasing has been matched with intake temperature. This result suggests that the effects of wall temperature on HCCI are mostly during the gas-exchange portion of the cycle. The ceramic coatings were able to very slightly decrease the thermal width, increase the burn rate, increase the combustion efficiency, and decrease the cumulative heat loss. The combustion efficiency increased with the lower surface area to volume ratio piston and the lower compression ratio. Lastly, the compression ratio comparison showed a noticeable effect on the temperature distribution due to the effect of pressure on ignition delay, and the variation of TDC temperature required to match combustion phasing.

NOx process inhibition and energy efficiency improvement in new swirl modification device for steel slag based on coal combustion

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Junxiang Guo ◽  
Lingling Zhang ◽  
Daqiang Cang ◽  
Liying Qi ◽  
Wenbin Dai ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Flue Gas ◽  
Coal Combustion ◽  
Steel Slag ◽  
Coal Ash ◽  
Combustion Efficiency ◽  
Gas Temperature ◽  
Staged Combustion ◽  
Energy Efficiency Improvement ◽  
Swirl Combustion

Abstract In this study, a novel swirl combustion modified device for steel slag was designed and enhanced with the objective of achieving highly efficient and clean coal combustion and also for achieving the whole elements utilization of coal. Coal ash and steel slag were melted in the combustion chamber and subsequently entered the slag chamber. The detrimental substances solidified and formed crystals, which allowed for the comprehensive utilization of the ash and slag. Our experiments mainly aimed to mitigate the formation of NOx, while using the heat and slag simultaneously during the coal combustion without a combustion efficiency penalty. The increase in the device’s energy efficiency and reduction in the NOx emissions are important requirements for industrialization. The experiments were carried out in an optimized swirling combustion device, which had a different structure and various coal feeding conditions in comparison to previously reported devices. The fuel-staged and non-staged combustion experiments were compared under different coal ratios (bitumite:anthracite). For the fuel-staged combustion experiments, the NOx concentration in the flue gas was observed to decrease significantly when the coal ratio of 1:1, an excess air coefficient of 1.2, and a fuel-staged ratio of 15:85 were used. Under these conditions, the flue gas temperature was as high as 1,620°C, while the NOx concentration was as low as 320 mg/m3 at 6 % O2. The air-surrounding-fuel structure that formed in the furnace was very beneficial in reducing the formation of NOx. In comparison to other types of coal burners, the experimental combustion device designed in this study achieved a significant reduction of NOx emissions (approximately 80 %).

Effect of Air Distribution on Solid Fuel Bed Combustion

1997 ◽  
Vol 119 (2) ◽  
pp. 120-128 ◽  
Author(s):  
J. T. Kuo ◽  
W.-S. Hsu ◽  
T.-C. Yo
Keyword(s):  
Combustion Efficiency ◽  
Pollutant Emissions ◽  
Air Distribution ◽  
Gas Temperature ◽  
One Dimensional ◽  
Supply And Distribution ◽  
Air Supply ◽  
Burning Rates ◽  
Side Walls ◽  
Detailed Chemical

One important aspect of refuse mass-burn combustion control is the manipulation of combustion air. Proper air manipulation is key to the achievement of good combustion efficiency and reduction of pollutant emissions. Experiments, using a small fix-grate laboratory furnace with cylindrical combustion chamber, were performed to investigate the influence of undergrate/sidewall air distribution on the combustion of beds of wood cubes. Wood cubes were used as a convenient laboratory surrogate of solid refuse. Specifically, for different bed configurations (e.g., bed height, bed voidage, bed fuel size, etc.), burning rates and combustion temperatures at different bed locations were measured under various air supply and distribution conditions. One of the significant results of the experimental investigation is that combustion, with air injected from side walls and no undergrate air, has the maximum combustion efficiency. On the other hand, combustion with undergrate air achieves higher combustion rates but with higher CO emissions. A simple one-dimensional model was constructed to derive correlation of combustion rate as a function of flue gas temperature and oxygen concentration. Despite the fact that the model is one-dimensional and many detailed chemical and physical processes of combustion are not considered, comparisons of the model predictions and the experimental results indicate that the model is appropriate for quantitative evaluation of bed-burning rates.

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.

COMBUSTION OF A GAS SUSPENSION OF COAL DUST IN A SWIRLING FLOW

2021 ◽  
pp. 139-147
Author(s):  
K.M. Moiseeva ◽  
◽  
A.Yu. Krainov ◽  
E.I. Rozhkova ◽  
◽  
...  
Keyword(s):  
Flow Velocity ◽  
Swirling Flow ◽  
Coal Dust ◽  
Combustion Efficiency ◽  
Dust Particles ◽  
Gas Temperature ◽  
Flow Swirl ◽  
Angular Component ◽  
Air Suspension ◽  
The Impact

Swirling combustion is currently one of the most important engineering problems in physics of combustion. There is a hypothesis on the increase in the combustion efficiency of reacting gas mixtures in combustion chambers with swirling flows, as well as on the increase in the efficiency of fuel combustion devices. In this paper, it is proposed to simulate a swirling flow by taking into account the angular component of the flow velocity. The aim of the study is to determine the effect of the angular component of the flow velocity on the characteristics of the flow and combustion of an air suspension of coal dust in a pipe. The problem is solved in a twodimensional axisymmetric approximation with allowance for a swirling flow. A physical and mathematical model is based on the approaches of the mechanics of multiphase reacting media. A solution method involves the arbitrary discontinuity decay algorithm. The impact of the flow swirl and the size of coal dust particles on the gas temperature distribution along the pipe is determined.

Research and Design of the Control System for Natural Gas Heater

2013 ◽  
Vol 842 ◽  
pp. 541-545
Author(s):  
Yun Guo ◽  
Zhi Qiang Huang ◽  
Shun Xin Yang
Keyword(s):  
Control System ◽  
Natural Gas ◽  
Power Plants ◽  
Production Efficiency ◽  
Combustion Efficiency ◽  
Gas Temperature ◽  
Technical Requirements ◽  
Real Time Measurement ◽  
And Control ◽  
Measurement And Control

Natural gas heaters are widely used in gas-fired power plants to meet the combustion needs and to improve the combustion efficiency. For the control features and technical requirements of the natural gas heater, the computer automatic control system for natural gas heater has been designed,and realizes the temperature and liquid level real time measurement and control. The system increases significantly the control accuracy of natural gas temperature, eliminates potential unsafety and improves production efficiency.

Investigation of Filtered Rayleigh Scattering Techniques for Rig Testing Diagnostics

2014 ◽  
Author(s):  
Jordi Estevadeordal ◽  
Dmitry Opaits ◽  
Chiranjeev Kalra
Keyword(s):  
Rayleigh Scattering ◽  
High Pressures ◽  
Imaging Techniques ◽  
Mixing Layer ◽  
Temperature Measurements ◽  
Temperature Fields ◽  
Gas Temperature ◽  
Iccd Camera ◽  
Gas Molecules ◽  
Combustion Tests

A laboratory investigation of Filtered Rayleigh Scattering (FRS) techniques for high-resolution and high-accuracy temperature measurements in rig tests with high pressures and temperatures and combustion is presented. Imaging techniques based on filtered Rayleigh scattering have the potential for two-dimensional (2D) and near wall measurement of gas velocity and temperature fields among other properties. For gas temperature measurements, laser Rayleigh scattering from gas molecules are typically captured with an ICCD camera and temperature can be inferred from the number density measured from the image intensities. The accuracy challenges associated with property spatial variations, gas composition, and pressure and temperature conditions are investigated for the rig test environments. Representative examples including mixing layer, jet and vortex flows and flame and combustion tests are presented.

scholarly journals Numerical Modeling of Biomass and Solid Waste-Based Syngas Fuels Combustion

2015 ◽  
Vol 11 (2) ◽  
Keyword(s):  
Solid Waste ◽  
Mass Fraction ◽  
Mixture Fraction ◽  
Combustion Process ◽  
Plastic Waste ◽  
The Other ◽  
Gas Temperature ◽  
Saw Dust ◽  
Gas Fuel ◽  
Lower Heating

The combustion of syngas fuels in gas turbine combustor is presented in this paper. The principal objective is to test the performance of the combustion process using non-conventional fuels produced from the gasification of biomass and solid waste. Three dimensional syngas combustion simulations were performed in this study. The mixture fraction/pdf and the P1 radiation models were used to model the non-premixed turbulent combustion. The syngas fuels are derived from the gasification of wood saw dust, wooden pellet and nonrecycled solid waste plastics. The effect of syngas fuel compositions and lower heating values on the combustion process was investigated. The power from the combustor was kept constant at 60 kW for all the syngas fuels tested in this study. The results show a decrease of the peak gas temperature inside the combustor for the syngas fuels compared to conventional fossil gas fuel. The peak gas temperature inside the combustor decreases by 16.1%, 19.8%, and 17.2% respectively for the syngas 1 (derived from plastic waste), syngas 2 (derived from wood saw dust) and syngas 3 (derived from wooden pellets) compared to natural gas fuel. The highest average NO mass fraction at the combustor exit was obtained with syngas 1 (plastic waste) compared to the other syngas fuels due to the high lower heating value. The highest average CO2 mass fraction at the exit of the combustor was obtained with syngas 2 (wood saw dust) compared to the other syngas due to the high amount of CO2 in the syngas fuel (15%).

Effect of Wood Biomass Addition on the Char Making Process of Waste Plastic for Controlling the Combustion Efficiency

2012 ◽  
Vol 31 (4-5) ◽  
pp. 465-470
Author(s):  
Y. Ito ◽  
M. Hasegawa ◽  
Y. Kashiwaya ◽  
M. Iwase
Keyword(s):  
Waste Heat ◽  
Xrd Analysis ◽  
Reaction Rates ◽  
Combustion Efficiency ◽  
Industrialized Countries ◽  
Wood Biomass ◽  
Carbon Structure ◽  
Key Technology ◽  
Reactivity Test ◽  
Crystallization Degree

AbstractAfter Kyoto protocol, many companies and institutions in the industrialized countries focused on the energy saving and the utilization of waste heat and materials widely for reducing the CO2 emission. In such a circumstance, it is key technology for reducing CO2 emission by using the waste materials efficiently such as a plastic and wood biomass.In this paper, a method for improving the reactivity of plastic char using wood biomass was investigated. The XRD analysis was performed for elucidating the carbon structure change by addition of wood to PE (polyethylene) and reactivity test with O2 gas was carried out to clarify the reaction rates of the mixtures of PE and wood.It was found that the crystallization degree of char decreased continuously with the addition of wood to polyethylene, which meant that the reactivity of polyethylene char increased.

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