Two-Stage Fuel Research Articles

Development of the first Raman scattering thermometry during the first stage ignition in a rapid compression machine and determination of detection limits for NO-LIF

The interaction of recirculated NOX with two-stage fuels in the early combustion process is not fully understood, especially at lower temperatures. Recently developed kinetic combustion models try to reproduce these interactions. To validate and improve these new models, accurate quantitative measurements of temperature in the combustion process are necessary. Previous works used Rayleigh or LIF techniques and have not reached an accuracy appropriate for the kinetic models. The present work demonstrates the feasibility of 1D spatially-resolved temperature measurements in a rapid compression machine with Raman scattering for the first time. The temperature data is measured with high precision during the first stage ignition of n-pentane as a two-stage fuel. Additionally, the temperature data is needed to determine possible NO detection limits. Therefore, the influence on combustion temperatures from NOX-doping are compared with undoped gas mixtures is determined by spontaneous Raman scattering of N2 excited by a KrF* excimer laser. The results show that spatially resolved N2-Raman thermometry is feasible with a precision of approximately 3 % by investigating 30 averaged shots. The measured temperature profile in the first stage reveals a remarkable temperature difference between the edges and the inner area of the combustion volume due to differences in the reactivity, which is affected by chemistry and heat loss. Additionally, the NO detection limit is determined to be 30 ppm when averaging 10 single shots during an NO-doped N2 mixture.

Study on Control-Oriented Emission Predictions of PPCI Diesel Engine with Two-Stage Fuel Injection

Study on Control-Oriented Emission Predictions of PPCI Diesel Engine with Two-Stage Fuel Injection

Effects of High-Pressure Two-Stage Fuel Injection on the Diesel Engine Performance in Start Process

Effects of High-Pressure Two-Stage Fuel Injection on the Diesel Engine Performance in Start Process

Analysis of Two-Stage Fuel Combustion in Multi-Fuel Boilers

The significant growth of industry in the second half of the 20th century led to a number of problems, one of the most important problems is the protection of the environment from pollution. The main source of air pollution is heat and power generating plants, which are based on combustion processes. The largest pollutant is thermal power plants, which burn a large volume of fossil fuel and form a corresponding amount of toxic substances, in particular nitrogen and sulfur oxides. In this paper, combustion processes with various burner devices will be considered and two fuels – natural gas, fuel oil. One of the most important tasks operation of power equipment is the development and widespread use of effective methods to reduce the formation of harmful substances and determining the optimal modes of fuel combustion, ensuring a minimum level of emissions of toxic combustion products. Two-stage fuel combustion is an effective method of reducing nitrogen oxide emissions. In two-stage combustion, one fuel burnout zone is replaced by several zones, as isolated as possible. The paper will compare several options for the implementation of two-stage combustion in the boiler. The influence of boiler load on the concentration of nitrogen oxides in the exhaust gases is analyzed. Also at two-stage combustion of fuel oil in gas-oil boilers reliability of screen surfaces of heating as a result of decrease in the maximum falling heat streams on a screen surface of heating of a copper increased.

Numerical Investigation on Effects of Assigned EGR Stratification on a Heavy Duty Diesel Engine with Two-Stage Fuel Injection

External exhaust gas recirculation (EGR) stratification in diesel engines contributes to reduction of toxic emissions. Weak EGR stratification lies in that strong turbulence and mixing between EGR and intake air by current introduction strategies of EGR. For understanding of ideal EGR stratification combustion, EGR was assigned radically at −30 °CA after top dead center (ATDC) to organize strong EGR stratification using computational fluid dynamics (CFD). The effects of assigned EGR stratification on diesel performance and emissions are discussed in this paper. Although nitric oxides (NOx) and soot emissions are both reduced by means of EGR stratification compared to uniform EGR, the trade-off between NOx and soot still exists under the condition of arranged EGR stratification with different fuel injection strategies. A deterioration of soot emissions was observed when the interval between main and post fuel injection increased, while NO emissions increased first then reduced. The case with a 4 °CA interval between main and post fuel injection is suitable for acceptable NO and soot emissions. Starting the main fuel injection too early and too late is not acceptable, which results in high NO emissions and high soot emissions respectively. The start of the main fuel injection −10 °CA ATDC is suitable.

Chemical Looping Gasification of Coal in a 5 kWth Interconnected Fluidized Bed with a Two-Stage Fuel Reactor

Chemical looping gasification (CLG) is a novel technology using lattice oxygen in a solid oxygen carrier (OC) for syngas production. The present work investigated the CLG performance of coal in a 5 kWth interconnected fluidized bed, in which the fuel reactor was designed as a two-stage-based circulating bed. The fresh OC from the air reactor entered into the upper stage of the fuel reactor, in which it was reduced by syngas. Then, the partial reduction of the OC was circulated to the bottom stage of the fuel reactor to be reduced further to low-valence metal oxide and catalyze the process of coal gasification. Afterward, the reduced OC was transported to the air reactor for regeneration. The influences of the coal feeding rate, gasification temperature, and gasification agent on the performance of CLG were evaluated in detail. The syngas yield and gasification efficiency were remarkably influenced by the coal feeding rate, with an optimal value of 487.5 g/h in the current unit. The high temperature promot...

Combustion Performance of Sewage Sludge in a Novel CLC System with a Two-Stage Fuel Reactor

Chemical looping combustion (CLC) is a promising and efficient technology for sewage sludge (SS) combustion with carbon capture. The CLC reactor configuration is crucial to the intimate contact between the solid phase and the gas phase species. This work proposed a novel CLC unit with a two-stage fuel reactor. Different from the conventional CLC unit with a single-stage bubbling bed as fuel reactor, two-stage fuel reactor design can make gas phase and solid phase be in adequate contact and achieve gas flow redistribution in the fuel reactor. On this unit, both cold and hot experiments were conducted. The gas-solid flow characteristics were studied on the cold model, and the system was successfully commissioned and in stable operation. No gas leakage occurred between reactors. In the hot experiments, SS from the municipal wastewater treatment plant was chosen as solid fuel and hematite with a size range of 0.3–0.45 mm was used as oxygen carrier. To thoroughly evaluate the performance of this noval CLC syst...

Role of Two-stage Fuel Injection in a Gasoline-fueled Compression Ignition Engine

Role of Two-stage Fuel Injection in a Gasoline-fueled Compression Ignition Engine

Simulation of Two-Stage Fuel Reactor Chemical Looping Hydrogen Process Using Solid Fuel

Chemical looping hydrogen (CLH) has become a promising technology for hydrogen production with inherent separation of carbon dioxide. Aspen Plus was used to simulate a two-stage fuel reactor CLH process of coal as solid fuel. Simulation results show that the two-stage reactor can fully convert the fuel and generate the maximum Fe0.947O component to react with the steam in steam reactor. The optimum OC/coal molar ratio in the two-stage fuel reactor was 2.8. The CO2 fraction of the flue gas in the fuel reactor reached 99% when the vapor was condensed at the temperature of 950 °C. The fraction of dry-based H2 in the steam reactor was nearly 100% when the steam reactor temperature was 700 °C and the steam/oxygen carrier molar ratio was 0.48.

Effect of Mixture Distribution Formed by Two-stage Fuel Injection of Different Ignitability Fuel on Ignition and Combustion Characteristics in PCCI Combustion

Effect of Mixture Distribution Formed by Two-stage Fuel Injection of Different Ignitability Fuel on Ignition and Combustion Characteristics in PCCI Combustion

Effect of Two-Stage Fuel Injection Parameters on NOx Reduction Characteristics in a DI Diesel Engine

The aim of this study was to confirm the effects of two-stage combustion on the combustion and NOx reduction characteristics of a four cylinder direct injection diesel engine. In order to analyze the combustion and emission characteristics, various injection parameters, such as injection quantity, injection timing and injection pressure were used under constant engine speed and engine load. In addition, the experimental results of two-stage combustion are compared to the single injection when injection timing is 5° BTDC. The experimental results showed that NOx emissions were significantly reduced when applying two-stage combustion. In particular, an injection strategy when the first and second injections have a same quantity, the results showed the maximum reduction of NOx emissions in this experiment. The NOx emissions were also reduced when the timing of the first injection was advanced. However, NOx emissions indicated almost similar concentration regardless of first injection timings when the first injection timing was earlier than 50° BTDC. In the case of soot emissions were slightly increased compare to the single injection cases at tested conditions.

Partial Fuel Stratification to Control HCCI Heat Release Rates: Fuel Composition and Other Factors Affecting Pre-Ignition Reactions of Two-Stage Ignition Fuels

Homogeneous charge compression ignition (HCCI) combustion with fully premixed charge is severely limited at high-load operation due to the rapid pressure-rise rates (PRR) which can lead to engine knock and potential engine damage. Recent studies have shown that two-stage ignition fuels possess a significant potential to reduce the combustion heat release rate, thus enabling higher load without knock. This study focuses on three factors, engine speed, intake temperature, and fuel composition, that can affect the pre-ignition processes of two-stage fuels and consequently affect their performance with partial fuel stratification. A model fuel consisting of 73 vol.% isooctane and 27 vol.% of n-heptane (PRF73), which was previously compared against neat isooctane to demonstrate the superior performance of two-stage fuels over single-stage fuels with partial fuel stratification, was first used to study the effects of engine speed and intake temperature. The results for PRF73 show that increasing engine speed from 1200 to 1600 rpm causes almost no change in φ-sensitivity, which is defined by the advancement of combustion phasing for an increase in equivalence ratio. Consequently, the maximum combustion pressure rise rate (PRRmax) can be reduced substantially with partial fuel stratification at this higher speed as it was at 1200 rpm. In contrast, increasing intake temperature from 60°C to 174°C eliminates the low temperature heat release of PRF73. Despite the single-stage ignition at this temperature, PRF73 still shows a weak but definitive φ-sensitivity, likely due to the relatively strong intermediate temperature heat release before hot ignition. As a result, PRR max was reduced modestly with partial fuel stratification. This PRF73 result is distinctively different from that of isooctane at the same intake temperature. To study the importance of fuel composition, PRF73 is compared with a low-octane, gasoline-like distillate fuel, termed Hydrobate, which could be readily produced from petroleum feedstocks. With the similar HCCI reactivity to PRF73, Hydrobate shows little difference in φ-sensitivity and performs similarly with partial fuel stratification compared to PRF73. This result indicates that it is the overall fuel HCCI reactivity, rather than the exact fuel composition, that determines the φ-sensitivity and the consequent performance with partial fuel stratification. © 2011 SAE International.

404 二段燃料噴射により混合気濃度不均一性を与えた圧縮着火燃焼に関する研究(OS6-1熱機関・燃焼現象の高度解析)

404 二段燃料噴射により混合気濃度不均一性を与えた圧縮着火燃焼に関する研究(OS6-1熱機関・燃焼現象の高度解析)

Tailoring HCCI heat-release rates with partial fuel stratification: Comparison of two-stage and single-stage-ignition fuels

This work concerns one of the major issues restricting the application of homogeneous charge compression-ignition (HCCI) engines, overly rapid combustion at high-load conditions, which can lead to engine knock and potential engine damage. To overcome this problem, partial fuel stratification was used, where most fuel was premixed with intake air and the rest of the fuel was directly injected during the compression stroke. To be effective, this technique depends critically on the fuel autoignition chemistry. PRF73, a mixture of 73 vol% isooctane and 27 vol% n-heptane that exhibits two-stage ignition under these conditions, successfully enabled control of the combustion heat-release rate with properly adjusted injection parameters. More than a 70% reduction in the maximum pressure-rise rate (PRR max) was achieved, compared to the fully premixed case at the same combustion phasing. Meanwhile, combustion remained stable, efficient, and clean. In particular, NO x emissions were kept well below the US-2010 limits. On the other hand, isooctane, which exhibits single-stage ignition under the present conditions, responded much differently to partial fuel stratification. Instead of reducing PRR max, isooctane partial stratification increased PRR max and drastically raised NO x emissions and combustion instability. Such differences between single- and two-stage fuels result from the different response of their autoignition rates to the variations in equivalence ratio produced by partial fuel stratification, termed ϕ-sensitivity.

1001 二段燃料噴射における低温酸化反応と濃度不均一性がPCCI燃焼に与える影響(GS6-1 熱工学)

1001 二段燃料噴射における低温酸化反応と濃度不均一性がPCCI燃焼に与える影響(GS6-1 熱工学)

Fundamental Study on DISC Engine with Two-Stage Fuel Injection.

An experimental study has been carried out on the combustion characteristics of a newly proposed direct-injection stratified-charge SI engine. A water-cooled, 4-cylinder, 4-stroke-cycle diesel engine with a square piston cavity was modified to permit the installation of a spark plug. Charge stratification was accomplished with two-stage fuel injection. The main fuel was injected at the early stage of the induction stroke to form a lean homogeneous mixture, and the auxiliary fuel was injected just before the spark firing to produce a rich mixture near the spark plug. The results showed that the lean limit was extended up to approximately the air-fuel ratio of 25 without increasing in fuel consumption and HC emissions. The optimum quanTITY of auxiliary fuel was found to extend the lean limit and to reduce the fuel consumption. Charge stratification caused a reduction in the ignition delay.

Fundamental Study on DISC Engine with Two-Stage Fuel Injection.

An experimental study has been carried out on the combustion characteristics of a newly proposed direct-injection stratified-charge SI engine. A water-cooled, 4-cylinder, 4-stroke-cycle diesel engine with a square piston cavity was modified to permit the installation of a spark plug. Charge stratification was accomplished with two-stage fuel injection. The main fuel was injected at the early stage of the induction stroke to form a lean homogeneous mixture, and the auxiliary fuel was injected just before the spark firing to produce a rich mixture near the spark plug. The results showed that the lean limit was extended up to approximately the air-fuel ratio of 25 without increasing in fuel consumption and HC emissions. The optimum quanTITY of auxiliary fuel was found to extend the lean limit and to reduce the fuel consumption. Charge stratification caused a reduction in the ignition delay.

Aerator From a Two-Stage Fuel Pump Used in Transporting Live Fish

Aerator From a Two-Stage Fuel Pump Used in Transporting Live Fish