The Combustion Efficiency of Furnace Exhaust Gas Combustors: a Study of Jet Mixing in a Reacting Cross-Flow

2000 ◽  
Vol 155 (1) ◽  
pp. 31-49 ◽  
Author(s):  
B. POPOVIC ◽  
M.J. THOMSON ◽  
M.F. LIGHTSTONE
Keyword(s):  
Cross Flow ◽  
Combustion Efficiency ◽  
Exhaust Gas ◽  
Jet Mixing

scholarly journals The Effect of Jet Mixing on the Combustion Efficiency of a Hot Fuel-Rich Cross-Flow

2001 ◽  
Vol 163 (1) ◽  
pp. 211-228 ◽  
Author(s):  
M. BOUTAZAKHTI ◽  
M J. THOMSON ◽  
M. LIGHTSTONE
Keyword(s):  
Cross Flow ◽  
Combustion Efficiency ◽  
Jet Mixing

Vortex modeling of single and multiple dilution jet mixing in a cross flow

1986 ◽  
Vol 2 (4) ◽  
pp. 354-360 ◽  
Author(s):  
A. R. Karagozian ◽  
T. T. Nguyen ◽  
C. N. Kim
Keyword(s):  
Cross Flow ◽  
Jet Mixing

Research and Improvement on Calculation Method of Optimal Excess Air Ratio

2014 ◽  
Vol 536-537 ◽  
pp. 1583-1586
Author(s):  
Jun Xiong Qi
Keyword(s):  
Heat Loss ◽  
Correction Factor ◽  
Calculation Method ◽  
Traditional Method ◽  
Combustion Efficiency ◽  
Exhaust Gas ◽  
Incomplete Combustion ◽  
Excess Air

By analyzing the relations of the excess air ratio to heat loss due to exhaust gas, chemical incomplete combustion and combustibles in refuse, the traditional method for solving the optimal excess air ratio is improved. A correction factor is proposed for heat loss due to combustibles in refuse, making the solving method more accurate, which is of great importance for improving the combustion efficiency of the boiler.

Use of Early Exhaust Valve Opening to Improve Combustion Efficiency and Catalyst Effectiveness in a Multi-Cylinder RCCI Engine System: A Simulation Study

2014 ◽  
Author(s):  
Anand Nageswaran Bharath ◽  
Nitya Kalva ◽  
Rolf D. Reitz ◽  
Christopher J. Rutland
Keyword(s):  
System Simulation ◽  
Combustion Efficiency ◽  
Exhaust Valve ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Flow Rates ◽  
Low Load ◽  
Valve Opening ◽  
Engine System ◽  
Exhaust Gas Temperature

Low Temperature Combustion (LTC) strategies such as Reactivity Controlled Compression Ignition (RCCI) can result in significant improvements of fuel economy and emissions reduction. However, they can produce significant carbon monoxide and unburnt hydrocarbon emissions at low load operating conditions due to poor combustion efficiencies at these operating points, which is a consequence of the low combustion temperatures that cause the oxidation rates of these species to slow down. The exhaust gas temperature is also not high enough at low loads for effective performance of turbocharger systems and diesel oxidation catalysts (DOC). The DOC is extremely sensitive to exhaust gas temperature changes and lights off only when a certain temperature is reached, depending on the catalyst specifications. Uncooled EGR can increase combustion temperatures, thereby improving combustion efficiency, but high EGR concentrations of 50% or more are required, thereby increasing pumping work and reducing volumetric efficiency. However, with early exhaust valve opening, the exhaust gas temperature can be much higher, allowing lower EGR flow rates, and enabling activation of the DOC for more effective oxidization of unburnt hydrocarbons and CO in the exhaust. In this paper, a multi-cylinder engine system simulation of RCCI at low load operation with early exhaust valve opening is presented, along with consideration of the exhaust aftertreatment system. The combustion process is modeled using the 3D CFD code, KIVA, and the heat release rates obtained from this combustion are used in a GT-Power model of a turbocharged, multi-cylinder light-duty RCCI engine for a full system simulation. The post-turbine exhaust gas is fed into GT-Power’s aftertreatment model of the engine’s DOC to determine the catalyst response. It is confirmed that opening the exhaust valve earlier increases the exhaust gas temperature, and hence lower EGR flow rates are needed to improve combustion efficiency. It was also found that exhaust temperatures of around 457 K are required to light off the catalyst and oxidize the unburnt hydrocarbons and CO effectively. Performance of the DOC was drastically improved and higher amounts of unburnt hydrocarbons were oxidized by increasing the exhaust gas temperature.

scholarly journals Combustion behavior of rotary solid porous burners (RSPB)

2020 ◽  
Vol 187 ◽  
pp. 03012
Author(s):  
Niwat Ketchat ◽  
Bundit Krittacom
Keyword(s):  
Porous Media ◽  
Combustion Efficiency ◽  
Wire Mesh ◽  
Fuel Load ◽  
Exhaust Gas ◽  
Input Rate ◽  
Air Flow Rate ◽  
Experimental Conditions ◽  
Complete Combustion ◽  
Combustion Behavior

The combustion behavior of rotary solid porous burners (RSPB), i.e., temperature (T), exhaust gas (CO and NOx) and combustion efficiency (nc) were investigated. The stainless wire-mesh type of porous media was selected as porous absorber with porosity of 0.82, thickness of 4.2 mm. The rice husk was used as the fuel with the humidity around 12-14%. The experiment showed that the T tends to increase following the rotating velocity (ro) rising around 0.5-1 rpm. When a ro increased to 1.5 rpm, a T had tendency decreasingly. Because, a ro was too high resulting in the fuel in combustion chamber were ejected quickly then the reaction time reduced not enough to burn fuel, leading to incomplete combustion. The air flow rate (Qa) of 40 m3/h and the fuel load input rate (Qf) of 2.3 kg/h, gave the highest of T due to the system become complete combustion. Corresponding to the level of CO, the least level was obtained at ro = 1 rpm, Qf = 2.3 kg/h and Qa = 40 m3/h. The qc yielded highest with 93.7% at the same condition. The NOx in this research was considered as low, not more than 40 ppm in all experimental conditions.

scholarly journals Improvement of Mixing Efficiency in the Combustion Chamber of a Powder-Fuel Ramjet Engine

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenxiong Xi ◽  
Jian Liu ◽  
Ren Mengfei
Keyword(s):  
Combustion Chamber ◽  
Simulation Method ◽  
Combustion Efficiency ◽  
Powder Injection ◽  
Mixing Efficiency ◽  
Exhaust Gas ◽  
Gas Generator ◽  
Head Region ◽  
Fuel Gas ◽  
Ramjet Engine

The challenge of the powder-fuel ramjet is to improve the mixing effect of powder-fuel with oxidizing agents and combustion efficiency. To improve the mixing and combustion efficiency of the powder-fuel ramjet engine, three configurations in head shapes and three exhaust gas inlet patterns of the engine are designed based on a typical powder-fuel ramjet engine combustion chamber. The effect of the head shapes and exhaust gas inlet patterns is analyzed and compared by the three-dimensional numerical simulation method. A comprehensive model validation is built, and the calculation results of the k-ε standard model are compared with the experimental data. The results show that the cylindrical head forms a recirculation zone at the head of the combustion chamber, which leads to powder deposition in the head region of the chamber. The design with the round head and the coned head reduces the recirculation inside the head region, and the exhaust gas from the fuel gas generator has benefits in powder injection and mixing inside the combustion chamber. The exhaust gas inlet of the inclined six hole type has benefits in the mixing of powder and high temperature exhaust gas because it generates strong flow impingement in the core part of the chamber.

Experimental Investigation on the Effects of Swirlers Configurations and Air Inlet Partitioning in a Partially Premixed Double High Swirl Gas Turbine Model Combustor

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Amir Mardani ◽  
Benyamin Asadi Rekabdarkolaei ◽  
Hamed Rezapour Rastaaghi
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Exhaust Gas ◽  
Liquefied Petroleum Gas ◽  
Gas Temperature ◽  
Air Inlet ◽  
Flow Channeling ◽  
German Aerospace ◽  
Exhaust Gas Temperature ◽  
Turbine Model

Abstract In this work, a double-high swirl gas turbine model combustor (GTMC) has been experimentally investigated to identify the effects of air partitioning and swirlers geometry on combustion characteristics in terms of flame stability, exhaust gas temperature, NOx generation, and combustion efficiency. This high swirl model combustor is originally developed in the German Aerospace Center (DLR) and known as GTMC and recently reconstructed at Sharif University's Combustion Laboratory (named as SGTMC). Here, SGTMC run for liquefied petroleum gas (LPG) fuel and air oxidizer at room temperature and atmospheric pressure. Eleven different burner geometries, M1–M11, are considered for the aims of this work. Furthermore, the effects of burner confinement are also investigated. The results show that under the confined state, the flame has a lower width and height than the unconfined one. Exchanging the swirlers of annular and central air inlets shows a more stable and lifted V type flame with almost zero levels of CO and CH4. In addition, measurement showed that the annular swirler removing leads to incomplete combustion. Moreover, an increment in discharged air velocity leads to more completed combustion and less pollutant exhaust gas but the attachment of flame to the burner hub. Strengthening the flow channeling is not reasonable in terms of emission aspects. Moreover, burner configuring to counterrotating swirlers leads to a more stable flame but with lower combustion efficiency. Among 11 test cases, the original configuration and the case of exchanging the swirlers of annular and central air inlets are the best choices in terms of combustion efficiency and stability. Measurements show the improvement of burner stability, 2–10%, due to inlet air preheating.

Modulation of a Liquid-Fuel Jet in an Unsteady Cross-Flow

2001 ◽  
Author(s):  
Torger J. Anderson ◽  
William Proscia ◽  
Jeffrey M. Cohen
Keyword(s):  
Cross Flow ◽  
Flow Modulation ◽  
Jet Mixing ◽  
Physical Mechanisms ◽  
Fuel Flow ◽  
Fuel Jet ◽  
Spray Density ◽  
Jet Behavior ◽  
Unique Method ◽  
Spray Distribution

This paper describes an experimental study of a fuel jet in an unsteady cross flow as part of a program to evaluate active control of combustion instabilities that involve acoustic / spray coupling. The results provide insights into the different physical mechanisms through which the jet and cross flow interact and the degree to which acoustic velocity fluctuations modulate liquid jet mixing, penetration and spray distribution. They also provide a means of evaluating the effectiveness of fuel flow modulation for controlling fuel jet behavior, demonstrating that fluctuations in the downstream spray distribution can be significantly reduced by phased fuel flow modulation. The paper describes a unique method for modulating the fuel and a relatively simple diagnostic for evaluating the fuel spray density and uniformity.

Impact of intake port injection of water on boosted downsized gasoline direct injection engine combustion, efficiency and emissions

2019 ◽  
Vol 22 (1) ◽  
pp. 295-315 ◽  
Author(s):  
Reza Golzari ◽  
Hua Zhao ◽  
Jonathan Hall ◽  
Mike Bassett ◽  
John Williams ◽  
...  
Keyword(s):  
Direct Injection ◽  
Water Injection ◽  
Combustion Efficiency ◽  
Gasoline Direct Injection ◽  
Exhaust Gas ◽  
Combustion Engines ◽  
Gas Temperature ◽  
Fuel Ratio ◽  
Gasoline Direct Injection Engine ◽  
Exhaust Gas Temperature

Introduction of ever more stringent emission regulations on internal combustion engines beyond 2020 makes it necessary for original equipment manufacturers to find cost-effective solutions to improve the combustion engine efficiency and decrease its emissions. Highly efficient combustion engines can benefit from technologies such as cooled external exhaust gas recalculation and water injection. Among these technologies water injection can be used as a promising method to mitigate knock and significantly reduce the CO2 emissions. This is particularly important in highly downsized boosted engines which run under much higher intake pressures and are more prone to knocking combustion. In addition to anti-knock behaviour, water injection is also an effective method for reducing NOx emissions and exhaust gas temperature at high loads, which can protect the turbine in turbocharged engines. This study shows the influence of intake port injection of water on efficiency and emissions of a boosted downsized single-cylinder gasoline direct-injection engine in detail. Six different steady-state speed and load combinations were selected to represent the conditions that knocking combustion start to occur. Water ratio sweep tests were performed to find out the optimum water/fuel ratio at each test point and the impact on the combustion and emissions. In addition to gaseous emissions, impact of water injection on particle emissions was also investigated in this study. The results show the net indicated efficiency improved significantly (by a maximum of around 5% at medium load and around 15% at high load) up to a maximum level by increasing the injected water mass. Improvement in efficiency was mainly due to the increased heat capacity of charge and cooling effect of the injected water evaporation which reduced the in-cylinder temperature and pressure. Thus, knock sensitivity was reduced and more advanced spark timings could be used, which shifted the combustion phasing closer to the optimum point. However, increasing the water/fuel ratio further (more than 1 at medium load and more than 1.5 at high load) deteriorated the combustion efficiency, prolonged the flame development angle and combustion duration, and caused a reduction in the net integrated area of the P-V diagram. Efficiency improvements were lower at higher engine speed (3000 r/min) as the knock sensitivity was already reduced intrinsically. In terms of other, harmful, non-CO2 emissions, water injection was effective in reducing the NOx emissions significantly (by a maximum of around 60%) but increased the HC emissions as the water/fuel ratio increased. The results also show a significant reduction in particle emissions by adding water to the mixture and advancing the spark timing at medium and high loads. In addition, water injection also reduced the exhaust gas temperature by around 80°C and 180°C at medium and high loads, respectively.

scholarly journals The Effect of Varying Engine Conditions on Unregulated VOC Diesel Exhaust Emissions

2017 ◽  
Author(s):  
Kelly L. Pereira ◽  
Rachel Dunmore ◽  
James Whitehead ◽  
M. Rami Alfarra ◽  
James D. Allan ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Exhaust Emissions ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Diesel Emissions ◽  
Exhaust Gas ◽  
Emission Rates ◽  
Gas Composition ◽  
Engine Combustion ◽  
Exhaust Gas Emissions

Abstract. An extensive set of measurements were performed to investigate the effect of different engine conditions (i.e. load, speed, temperature, "driving scenarios") and emission control devices (with/without diesel oxidative catalyst, DOC) on the composition and abundance of unregulated exhaust gas emissions from a light-duty diesel engine. Exhaust emissions were introduced into an atmospheric chamber and measured using thermal desorption comprehensive two-dimensional gas chromatography coupled to a flame ionisation detector (TD-GC×GC-FID). In total, 16 individual and 8 groups of volatile organic compounds (VOCs) were measured in the exhaust gas, ranging from volatile to intermediate volatility. The total speciated VOC (∑SpVOC) emission rates varied significantly with different engine conditions, ranging from 70 to 9268 milligrams of VOC mass per kilogram of fuel burnt (mg kg-1). ∑SpVOC emission rates generally decreased with increasing engine load and temperature, and to a lesser degree, engine speed. The exhaust gas composition changed as a result of two main influencing factors, the DOC hydrocarbon (HC) removal efficiency and engine combustion efficiency. Increased DOC HC removal efficiency and engine combustion efficiency resulted in a greater percentage contribution of the C7 to C12 branched aliphatics and C7 to C12 n-alkanes, respectively, to the ∑SpVOC emission rate. The investigated DOC removed 46 ± 10 % of the ∑SpVOC emissions, with removal efficiencies of 83 ± 3 % for the single-ring aromatics and 39 ± 12 % for the aliphatics (branched and straight-chain). The DOC aliphatic removal efficiency generally decreased with increasing carbon chain length. The emission factors of n-nonane to n-tridecane were compared with on-road diesel emissions from a highway tunnel in Oakland California. Comparable emission factors were from experiments with relatively high engine loads and speeds, engine conditions which are consistent with the driving conditions of the on-road diesel vehicles. Emission factors from low engine loads and speeds (e.g. cold-start) showed no agreement with the on-road diesel emissions as expected, with the emission factors observed to be 2 to 8 times greater. To our knowledge, this is the first study which has explicitly discussed the effect of the DOC HC removal efficiency and combustion efficiency on the exhaust gas composition. With further work, compositional differences in exhaust gas emissions as a function of engine temperature, could be implemented into air-quality models, resulting in improved refinement and better understanding of diesel exhaust emissions on local air quality.

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