Effect of Cavity Coupling Factors of Opposed Counter-Flow Microcombustor on the Methane-Fueled Catalytic Combustion Characteristics

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Yunfei Yan ◽  
Ying Liu ◽  
Haojie Li ◽  
Weipeng Huang ◽  
Yanrong Chen ◽  
...  
Keyword(s):  
Methane Conversion ◽  
Catalytic Combustion ◽  
Maximum Velocity ◽  
Combustion Efficiency ◽  
Geometric Parameters ◽  
Combustion Stability ◽  
Gas Temperature ◽  
Counter Flow ◽  
Inlet Velocity ◽  
Exhaust Gas Temperature

In this work, numerical investigations of methane catalytic combustion in the opposed counter-flow microcombustor are conducted under various inlet velocities, equivalence ratios, and geometric parameters. The results indicate that the high temperature zone is mainly located at the front and middle parts of the reaction zone. With the increase of inlet velocity, both methane conversion and exhaust gas temperature decrease, while the methane concentration in the downstream area increases. Its maximum velocity limit is 2.9 m/s. Moreover, temperature step zones of opposed counter-flow are obviously located at the front and middle parts with different equivalence ratios. The combustion efficiency decreases slowly with the increase of equivalence ratios. More importantly, critical values about the geometric parameters are determined for keeping better thermal performance. It is concluded that inlet velocity limit and methane conversion rate can be significantly increased and the temperature distribution is more uniform via reducing inlet width L2 and inlet height H, increasing the length of the downstream parts L1 and the downstream entrance length L3. In general, the opposed counter-flow microcombustor with optimized structure has better combustion stability. This design offers another way for developing the opposed counter-flow microcombustor.

A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition

2016 ◽  
Vol 819 ◽  
pp. 272-276 ◽  
Author(s):  
Ali Ghanaati ◽  
Mohd Farid Muhamad Said ◽  
Intan Zaurah Mat Darus ◽  
Amin Mahmoudzadeh Andwari
Keyword(s):  
Spark Ignition ◽  
Combustion Stability ◽  
Spark Ignition Engines ◽  
Gas Temperature ◽  
New Approach ◽  
Surface Ignition ◽  
Spark Plug ◽  
Engine Combustion ◽  
Si Engines ◽  
Exhaust Gas Temperature

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.

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.

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.

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 Experimental investigation of distance between v-gutters on flame stabilization and NOx emissions

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 2971-2981 ◽  
Author(s):  
Dias Umyshev ◽  
Abay Dostiyarov ◽  
Andrey Kibarin ◽  
Galya Tyutebayeva ◽  
Gaziza Katranova ◽  
...  
Keyword(s):  
Bluff Body ◽  
Flame Stabilization ◽  
Temperature Fields ◽  
Flame Stability ◽  
Bluff Bodies ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Inlet Velocity ◽  
Exhaust Gas Temperature

Blow-off performance and NOx emissions of the propane and air mixture in a rectangular combustion chamber with bluff bodies were investigated experimentally and numerically. The effects of distance between bluff bodies on NOx emissions, the blow-off limit, and exhaust gas temperature were examined. It was observed that NOx emissions are highly dependent on distance between V-gutters. The re-circulation zone behind the bluff body expands in width based on the decrease of distance between V-gutters, and expands in length with the increase of inlet velocity. The temperature fields behind the bluff body show a similar change, the temperature behind the bluff body reaches its highest when the distance between V-gutters reaches 20 mm, meaning it has better flame stability. The blow-off limit is significantly improved with the decrease of distance between V-gutters. The blow-off limit is greatly improved by reducing the distance between the V-gutters. Maximum blow-off limit of 0.11 is reached in the case of 20 mm, compared with 0.16 at 50 mm at a speed of 10 m/s.

Experimental and Numerical Investigations in a Gas-Fired Boiler With Combustion Stabilizing Device

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Zhengming Yi ◽  
Zheng Zhou ◽  
Qian Tao ◽  
Zhiwei Jiang
Keyword(s):  
Heat Exchange ◽  
Combustion Process ◽  
Side Surface ◽  
Coke Oven ◽  
Combustion Stability ◽  
Nox Emissions ◽  
Gas Temperature ◽  
Safety And Reliability ◽  
Set Up ◽  
Exhaust Gas Temperature

The combustion stability has a significant influence on safety and reliability of a gas-fired boiler. In this study, a numerical model was first established and validated to investigate the effect of combustion stabilizing device on flow and combustion characteristics of 75 t/h blast furnace gas (BFG) and coke oven gas (COG) mixed-fired boiler. The results indicated that the device coupled with four corner burners enables the flame to spin upward around its side surface, which facilitates heat exchange between BFG and the device. Under stable combustion condition, the combustion stabilizing device can be used as a stable heat source and enhance heat exchange in the furnace. Then, to obtain optimal COG ratio, combustion process of different blending ratios were experimentally investigated. The experimental results revealed that the energy loss due to high exhaust gas temperature is relatively high. COG ratio should be set up taking into account both boiler efficiency and NOX emissions. When COG blending ratio is maintained about 20%, the thermal efficiency of the boiler is 88.84% and the NOX concentration is 152 mg/m3 at 6% O2, meeting NOX emissions standard for the gas boiler.

Investigation of Catalytic Combustion in the Rotary Regenerator Type Catalytic Combustor at Different Inlet Velocities

2017 ◽  
Author(s):  
Zhenkun Sang ◽  
Xiaojing Lv ◽  
Zemin Bo ◽  
Yiwu Weng
Keyword(s):  
Gas Turbine ◽  
Catalytic Combustion ◽  
Calorific Value ◽  
Combustion Characteristic ◽  
Gas Temperature ◽  
Inlet Velocity ◽  
Combustion Technology ◽  
New Type ◽  
Computational Fluid Dynamics Cfd ◽  
Catalytic Combustor

Ultra low calorific value gas (ULCVG) is hard to be realized by the conventional combustion technology. Most of them are discarded into atmosphere directly, causing the inadvertent waste and serous pollution. Currently, a new type gas turbine with catalytic combustion and rotary regenerator can be used to utilize these fuels and mitigate pollution. Differing from the conventional gas turbine, the chamber and regenerator of the new gas turbine is combined into one component, which is named rotary recuperative type catalytic chamber (RRTCC). The catalytic combustion is applied for RRTCC. The catalytic combustion characteristic of RRTCC is studied using the computational fluid dynamics (CFD). The results indicate that when the inlet velocity is 20 m/s, the methane conversion rate is 90%∼95%, and the corresponding outlet gas temperature is 1030∼1200K. When there is a variation of ±25% in the inlet velocity, the variation of methane conversation rate is −15% and 5% respectively, and the variation of outlet gas temperature is −6% and 2% respectively. Additionally, it is found that the hotspot temperature of combustor wall decreases with the increase of inlet velocity. The lowest value of hotspot temperature is about 1000K, which is higher than the ignition temperature of CH4. Therefore, the existence of hotspot temperature is useful for the catalytic ignition. The temperature distribution on the combustion side exhibits a smoking-pipe-like shape, as well as the recuperative side. The results can provide data reference for RRTCC design.

scholarly journals Exhaust Gas Emission Improvements of Water/Bunker C Oil-Emulsified Fuel Applied to Marine Boiler

2021 ◽  
Vol 9 (5) ◽  
pp. 477
Author(s):  
Tae-Ho Lee ◽  
Sang-Hyun Lee ◽  
Jee-Keun Lee
Keyword(s):  
Combustion Efficiency ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Oil Resources ◽  
Exhaust Gas Emission ◽  
O2 Concentration ◽  
Marine Boiler ◽  
Exhaust Gas Temperature ◽  
Fuel Effects ◽  
Exhaust Gas Emissions

In this study, emulsified fuels were prepared and produced by blending 0%, 5%, 15%, and 25% water with Bunker C oil to reduce the amount of air pollution emitted by ships and replace oil resources, and they were applied to an actual marine boiler to analyze the exhaust gas. The fuel effects on the improvement in exhaust gas emissions were as follows: The oxygen (O2) concentration increased by up to 4.2%, and that of carbon dioxide decreased by approximately 2.1%. Under the standard O2 concentration of 4%, the concentration of nitrogen oxides decreased by up to 31.41%, and that of sulfur oxides decreased by up to 37.47%. However, the exhaust gas temperature decreased by approximately 14.3%, and the combustion efficiency decreased by approximately 2.6%. Comparing the emission improvements, the combustion performance of the emulsified fuels was close to that of the conventional Bunker C fuel. These results indicate that the application of water-emulsified fuels to a marine boiler can reduce the amounts of certain air pollutants.

scholarly journals Experimental investigation of V-gutter flameholders

2017 ◽  
Vol 21 (2) ◽  
pp. 1011-1019 ◽  
Author(s):  
Dias Umyshev ◽  
Abay Dostiyarov ◽  
Musagul Tumanov ◽  
Quiwang Wang
Keyword(s):  
Bluff Body ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Bluff Bodies ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Flame Holder ◽  
Efficiency Increase ◽  
Exhaust Gas Temperature

Combustion characteristics and NOx emissions of propane and air mixture in a channel with a bluff body were investigated experimentally. Effects of the angle and type of the flameholder on the NOx emissions, blow-off limit, combustion efficiency, and exhaust gas temperature were examined. The results show that the NOx emissions are dependent on flameholder type and angle. Also it was observed that the perforated V-gutters considerably increases the blow-off performance. Moreover, the blow-off limit decreases as the geometrical size of flame-holder is increased. In addition, the combustion efficiency increase first and then decrease with the increase of the angle. The physics of the combustion process behind V-gutter flameholdes has been discussed. On the basis of experiment authors presented a modified version of the formula for calculation of lean blow-off limits when using bluff bodies, such as V-gutter flameholders.

Research on Exhaust Gas Temperature inside Catalytic Honeycomb Monolith Channel of Natural Gas Burner Start-up

2012 ◽  
Vol 621 ◽  
pp. 223-227 ◽  
Author(s):  
Zhi Hua Wang ◽  
Shi Hong Zhang
Keyword(s):  
Natural Gas ◽  
Gas Phase ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Start Up ◽  
Honeycomb Monolith ◽  
Exhaust Gas Temperature

This article discussed exhaust gas temperature and pollutant emissions characteristics of the combustion of rich natural gas-air mixtures in Pd metal based honeycomb monoliths in burner during the period of start-up process. The burner need to be ignited by gas phase combustion with the excessive air coefficient (a) at 1.3. The experimental results in catalytic monolith can be explained from SPFR. In this experiment, exhaust gas temperature and pollutant emissions were measured by thermocouple K of diameter 0.5 and the analyser every 1 minute, respectively. The finding would be applied for industrial catalytic combustion process start-up.

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