Methanol Injection Timing Research Articles

Study on cyclic variability of dual fuel combustion in a methanol fumigated diesel engine

An experimental study was conducted to investigate into the cyclic variations of diesel methanol dual fuel (DMDF) combustion on a methanol fumigated diesel engine. The effects of engine load, methanol substitution percent (MSP), injection timing and intake temperature on cyclic combustion variation were studied experimentally. In-cylinder pressure of 100 consecutive combustion cycles were recorded for each test case. The coefficient of variation (COV) of maximum in-cylinder pressure (pmax), maximum mass-averaged temperature (Tmax) and the indicated mean effective pressure (IMEP) were used to evaluate the cyclic variations of DMDF combustion. The results showed that the stability of DMDF combustion at high loads is comparable with that of neat diesel combustion. But the magnitude of cyclic DMDF combustion variations increases at light loads and more sensitive to the quantity of fumigated methanol. At light loads, COVpmax and COVTmax increase significantly and the crank angles corresponding to pmax and Tmax scatter more around with the increment of MSP. IMEP values show obvious fluctuations and are distributed in a wider range with an increase in MSP. DMDF combustion stability is very sensitive to intake temperature. At light loads the COVs of all combustion parameters decrease with the increment of intake temperature. In contrast, at high loads, the effect of intake temperature on the cyclic variations is quite small while there is a significant increase in the COVs when the intake temperature exceeds over 75°C. Overall, injection timings does no effect on cyclic variations of DMDF combustion.

Critical firing and misfiring boundary in a spark ignition methanol engine during cold start based on single cycle fuel injection

The influence of the mass of methanol injected per cycle, ambient temperature, injection and ignition timing, preheating methods, and supplying additional liquefied petroleum gas (LPG) injection into the intake manifold on the critical firing and misfiring boundary of an electronically injection controlled spark ignition (SI) methanol engine during cold start were investigated experimentally based on a single cycle fuel injection with cycle-by-cycle control strategy. The critical firing and misfiring boundary was restricted by all parameters. For ambient temperatures below 16 °C, methanol engines must use auxiliary start-aids during cold start. Optimal control of the methanol injection and ignition timing can realize ideal next cycle firing combustion after injection. Resistance wire and glow plug preheating can provide critical firing down to ambient temperatures of 5 °C and 0 °C, respectively. Using an additional LPG injection into the intake manifold can provide critical firing down to an ambient temperature of −13 °C during cold start. As the ambient temperature decreases, the optimal angle difference between methanol injection timing and LPG injection timing for critical firing of a methanol engine increases rapidly during cold start.

Regulated and unregulated emissions from a DISI methanol engine under homogenous combustion and light load

Abstract Experiments were conducted on a four-cylinder direct-injection spark-ignition (DISI) methanol engine under homogenous combustion mode and light load. The measurement methods in which combine with gas chromatography and liquid chromatography were used to separate and measure formaldehyde (HCHO) and unburned methanol unregulated emissions. The effects of methanol injection timing, ignition timing, excess air ratio and intake air temperature on HC, CO, and NO X regulated emissions, HCHO and unburned methanol unregulated emissions, and brake thermal efficiency were investigated experimentally. The study results show that advancing methanol injection timing, HC and CO emissions decrease, and NO X emission increases. Retarding ignition timing, HC and NO X emissions decrease, the effect of ignition timing on CO emission is small. The HC, CO, and NO X emissions of rich mixture are higher than those of lean mixture. For a lean mixture, HC emission rises. The HC and CO emissions decrease as intake air temperature increases. Intake air temperature of 55 °C is suitable for making an ideal mixture for a DISI methanol engine under homogenous combustion mode. The variations in emitted HCHO and unburned methanol show an opposite tendencies with the variations in the methanol injection timing, ignition timing, excess air ratio, intake air temperature and engine speed. Retarding methanol injection timing, advancing ignition timing, using lean mixture and reducing intake air temperature can decrease HCHO emission; and vice versa, unburned methanol emission decrease.

Experimental Study on Emission Characteristics of the PCCI-Di Combustion with DME and Methanol

The compound combustion of DME and methanol was realized in a four-cylinder direct-injection diesel engine by introducing a certain amount of DME into the manifold and injecting methanol into the cylinder using the injection system of the original engine. The effects of methanol injection timing and equivalence ratios of methanol and DME on the emissions characteristics of the compound combustion mode were experimental studied. The results showed that: methanol injection timing has greater impact on the emissions of compound combustion mode. When methanol is injected before 65oCABTDC, the engine shows HCCI combustion characteristics, the range of DME equivalence ratio is narrowed and the emission of HC is higher. When methanol is injected at 25oCABTDC, NOxemission amount is larger, while the HC and CO emission are lower. As Methanol injection timing is delayed to 5oCABTDC, CO emission increases sharply, but NOxand HC emissions are very low and not susceptible to the equivalence ratio of DME and methanol. Therefore, reasonable selection of methanol injection timing is the key to reducing the emissions of compound combustion mode.

Effect of injection and ignition timings on performance and emissions from a spark-ignition engine fueled with methanol

Optimal injection and ignition timings and the effects of injection and ignition timings on performance and emissions from a high-compression direct-injection stratified charge spark-ignition methanol engine have been investigated experimentally. The results have shown that direct-injection spark-ignition methanol engine, in which a non-uniform mixture with a stratified distribution can be formed, has optimal injection and ignition timings to obtain a good combustion and low exhaust emissions in the overall mode range. Both methanol injection timing and ignition timing have a significant effect on methanol engine performance, combustion, and exhaust emissions. At an engine speed of 1600 rpm, full load, and optimal injection and ignition timings, methanol engine can obtain shorter ignition delay, lesser cycle-by-cycle variation, the maximum in-cylinder pressure, the maximum heat release rate, and higher thermal efficiency compared to the case of non-optimized injection and ignition timings. For methanol engine, the optimization of injection timing and ignition timing can lead to an improvement of brake-specific fuel consumption of more than 10% compared to non-optimized case in the overall load range and engine speed of 1600 rpm. The best compromise between thermal efficiency and exhaust emissions is reached at optimal injection and ignition timings.

Emissions of Formaldehyde and Unburned Methanol from a Spark-Ignition Methanol Engine during Cold Start

The effects of the methanol injection quantity per cycle, the ignition timing, the methanol injection timing, the additional liquefied petroleum gas (LPG) injected into the inlet port, and the LPG ...

Effects of Fuel Injection Timing on Combustion and Emissions of a Spark-Ignition Methanol and Methanol/Liquefied Petroleum Gas (LPG) Engine during Cold Start

The combustion and emission characteristics of spark-ignition (SI) methanol and methanol/ liquefied petroleum gas (LPG) engines under different fuel injection timings during cold start have been studied by means of a cycle-by-cycle control strategy. The results showed that the methanol injection timing, the LPG injection timing, and the LPG injection timing delay relative to the methanol injection timing affect cold-start combustion characteristics and emissions of hydrocarbons, formaldehyde, and unburned methanol significantly. The methanol injection timing, the LPG injection timing, and the LPG injection timing delay relative to the methanol injection timing can be optimized to ensure that most fuels enter into the cylinder in the injection cycle and the following cycle and that reliable ignition and combustion happen in the third cycle. Optimal control of the fuel injection timing and the LPG injection timing delay relative to the methanol injection timing improves firing performances, reduces the hydr...

Experimental and Numerical Study of Methanol/Dimethyl Ether Dual-Fuel Compound Combustion

This paper experimentally and numerically investigates the effects of injection timing on combustion of a methanol/dimethyl ether (DME) dual-fuel compound at various methanol concentrations. In this dual-fuel compound combustion approach, methanol is directly injected into the cylinder, and DME is injected at the intake port. The experimental results indicate that methanol injection timing has an obvious effect on the heat release process of the dual-fuel compound combustion, and the effect of methanol concentration (i.e., the engine load) on injection timing is also evident. Late injection should be adopted to achieve smooth combustion and low NOx emissions at high methanol concentrations. Moderate injection timing should be adopted to achieve higher indicated thermal efficiency (ITE) at low methanol concentrations. The simulation results, using computational fluid dynamics (CFD) combined with reduced chemical kinetics, show that methanol injected at −26 °CA after top dead center (ATDC) has a remarkable effect on the high-temperature reaction of DME. In the case of injection timing at −26 °CA ATDC, the high-temperature combustion region is concentrated within the combustion chamber, which results in a higher NO concentration. With injection timing at −6 °CA ATDC, by contrast, the high-temperature combustion region is dispersed in the compression clearance and near the chamber wall, which leads to a relatively low NO concentration. Increasing injection pressure is an effective way to shorten the duration of the methanol/DME dual-fuel compound combustion achieved by later injection.

Combustion of a Spark-Ignition Methanol Engine during Cold Start under Cycle-by-Cycle Control

The effects of ambient temperature, intake air preheating, additional liquefied petroleum gas (LPG) injected into the inlet port, and methanol injection timing on the cold-start first cycle firing behavior of an electronically controlled inlet port methanol injection spark-ignition (SI) engine were investigated under a single-cycle fuel injection strategy. The results showed that the ambient temperature significantly affects the start firing behavior of the engine. When the ambient temperature is below 16 °C, the methanol engine can not be started reliably without auxiliary start aids even at the large amount of methanol injected per cycle. Using a glow plug to heat the engine inlet manifold and additional LPG injected into the inlet port result in a reliable firing of the engine. The amount of methanol injected per cycle for the reliable firing during the cold start of the engine reduces obviously, and the cold-start performance improves significantly with the rise in ambient temperature. If the fuel inj...

Combustion Control and Operating Range Expansion with Direct Methanol Injection in a Premixed Charge Compression Ignition Engine

The control of ignition timing, the suppression of rapid combustion, and the expansion of stable operating range upto higher load maintaining ultra low NOx and smokeless combustion were achieved by direct methanol injection in a premixed charge compression ignition engine. The combustion suppression effect increased with advancing methanol injection timing as the methanol widely distributed in combustion chamber. With increasing in methanol injection amount, the onset of low temperature oxidation delayed and the heat release in the low temperature oxidation decreased. This reduction of low temperature oxidation resulted in suppression of the temperature rise before the onset of high temperature oxidation, then delayed the onset of high temperature oxidation, and suppressed the rapid combustion. At high load the fraction of methanol injection amount have to be more than 50% to achieve normal combustion without too early ignition and knocking. Flame luminosities during the low and high temperature oxidations decreased with methanol injection.

309 メタノールの反応抑制効果による予混合圧縮着火燃焼の運転可能負荷領域拡大

The control of ignition and combustion behavior in a premixed charge compression ignission engine was investigated and ultra-low NOx and smokeless combustion was achived with direct in-cylinder injection of methanol as a reaction suppressor. The combustion suppression effect increases with advanced timing of methanol injection as the methanol becomes more widely distributed. With increases in methanol injection quantity, the appearance of low temperature oxidation is delayed and the heat release during low temperature oxidation decreases. With optimized methanol injection timing and injection quantity, the premixed charge compression ignition operational range could be expanded to 0.9 MPa IMEP, which is comparable to ordinary diesel operation.

A Study of Compression Ignition Engine Using Composite Fuel. (Effect of Injection Timing on Engine Performance and Exhaust Gas Characteristics).

Engine performance and combustion characteristic of prechamber-type diesel engine operated by gas-oil and methanol were investigated experimentally. In particular, the effect of injection timing difference between the gas-oil and methanol on the combustion phenomena was analyzed. As a result, when the gas-oil was used as a fuel of pilot injection, the ignition lag was mainly controlled by that of gas-oil. The maximum thermal efficiency takes place with an optimum methanol injection timing as the main fuel. The optimum methanol injection timing is about 2 to 3 crank angle before the ignition, since methanol vapor is required for smooth combustion based on the experimental results that the methanol combustion was initiated by the flame propagation from the combustion of gas-oil. Furthermore, it is recommended that a part of the some sprays of gas-oil and methanol be mixed and also distributed closely.