Speciation Analysis of Light Hydrocarbons and Hydrogen Production During Diesel Low Temperature Combustion

2011 ◽  
Author(s):  
Usman Asad ◽  
Arturo Mendoza ◽  
Kelvin Xie ◽  
Marko Jeftic ◽  
Meiping Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hydrogen Production ◽  
Oxidation Catalyst ◽  
Individual Species ◽  
Hydrocarbon Emissions ◽  
Exhaust Aftertreatment ◽  
Boost Pressure ◽  
Single Shot ◽  
Low Temperature Combustion ◽  
Temperature Combustion

The simultaneous reduction in engine-out NOx and soot emissions with diesel low temperature combustion (LTC) is generally accompanied by high levels of hydrocarbon (THC) and carbon monoxide (CO) emissions in the exhaust. To achieve clean diesel combustion in terms of low regulated emissions (NOx, soot, THC, and CO), the exhaust combustibles must be dealt with the exhaust aftertreatment (typically a diesel oxidation catalyst). In this work, engine tests were performed to realize LTC on a single-cylinder common-rail diesel engine up to 12 bar IMEP. A single-shot fuel injection strategy was employed to push the diesel cycles into LTC with exhaust gas recirculation (EGR). The combustibles in the exhaust were generally found to increase with the LTC load and were observed to be a function of the overall equivalence ratio. A Fourier transform infrared (FTIR) spectroscopy analysis of light hydrocarbon emissions found methane to constitute a significant component of the hydrocarbon emissions under the tested LTC conditions. The relative fraction of individual species in the hydrocarbons also changed, indicating a richer combustion zone and a reduction in engine-out THC reactivity. The hydrogen production was found to correlate consistently with the CO emissions, largely independent of the boost pressure or engine load under the tested LTC conditions. This research intends to identify the major constituents of the THC emissions and highlight the possible impact on exhaust aftertreatment.

Light Hydrocarbon Emissions From Diesel Low Temperature Combustion

2010 ◽  
Author(s):  
Kelvin Xie ◽  
Xiaoye Han ◽  
Graham T. Reader ◽  
Meiping Wang ◽  
Ming Zheng
Keyword(s):  
Low Temperature ◽  
Flame Temperature ◽  
Hydrogen Gas ◽  
Light Hydrocarbon ◽  
Hydrocarbon Emissions ◽  
Low Temperature Combustion ◽  
Temperature Combustion ◽  
Total Hydrocarbons ◽  
Very High ◽  
Load Conditions

A modern common-rail diesel engine was used to investigate hydrocarbon emissions under low temperature diesel combustion conditions. In this work, various EGR ratios and fuel mixing strategies were applied under a series of fixed-load conditions to progressively lower the flame temperature, which is verified by progressively reduced NOx emission. During the tests, the concentrations of total hydrocarbons, representative light hydrocarbon species (methane, acetylene, and ethylene), and hydrogen gas were measured with a set of emission analyzers, FTIR, and H2 mass-spectrometer. The trend for light hydrocarbon emissions was identified to be a function of both load and EGR ratio. Hydrogen gas can be emitted in significant quantities with the application of very high EGR. Under ultra-low NOx production conditions for medium and high load conditions, the light hydrocarbon species can account for the majority of hydrocarbon emissions.

Regulated emissions and speciated hydrocarbons from smokeless low-temperature combustion diesel engines with ultra-high exhaust gas recirculation and exhaust oxidation catalyst

2009 ◽  
Vol 223 (5) ◽  
pp. 673-683 ◽  
Author(s):  
T Li ◽  
H Ogawa
Keyword(s):  
Low Temperature ◽  
Exhaust Gas Recirculation ◽  
Combustion Regime ◽  
Oxidation Catalyst ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Toxic Emissions ◽  
Temperature Combustion ◽  
Clean Diesel Combustion ◽  
Gas Recirculation

With ultra-high exhaust gas recirculation (EGR) suppressing the in-cylinder soot and nitrogen oxides (NO x) formation as well as with the exhaust oxidation catalyst removing the engine-out total unburned hydrocarbon (THC) and carbon monoxide (CO) emissions, clean diesel combustion in terms of low regulated emissions (NO x, particulate matter, THC, and CO) can be established in an operating range up to 50 per cent load. However, unregulated emissions such as aldehydes, aromatics, and 1,3-butadiene, which are seen as a severe threat to human health, are concerned when operating the engine with ultra-high EGR. In this study, the THC emissions from a diesel engine operated with ultra-high EGR low-temperature combustion were speciated using Fourier transform infrared spectroscopy. Some unregulated toxic emissions including aldehydes, aromatics, 1,3-butadiene, and some low molecular hydrocarbons dramatically increase in the ultra-high EGR low-temperature combustion regime. The exhaust oxidation catalyst is effective to remove aldehydes and some unsaturated hydrocarbons, but aromatics and methane generated from the ultra-high EGR operation are hardly reduced, particularly at higher loads.

scholarly journals The impact of intake pressure on high exhaust gas recirculation low-temperature compression ignition engine combustion using borescopic imaging

2020 ◽  
pp. 146808742092602
Author(s):  
AK Sarangi ◽  
CP Garner ◽  
GP McTaggart-Cowan ◽  
MH Davy ◽  
GK Hargrave
Keyword(s):  
Low Temperature ◽  
Exhaust Gas Recirculation ◽  
Boost Pressure ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Compression Ignition Engine ◽  
Mass Fractions ◽  
Temperature Combustion ◽  
Gas Recirculation ◽  
The Impact

In diesel engines, high levels of exhaust gas recirculation can be used to achieve low-temperature combustion, resulting in low emission levels of both nitrogen oxides (NO x) and particulate matter. This work studied the effects of varying the intake manifold pressure on in-cylinder combustion processes and engine-out emissions from a light-duty single cylinder diesel engine under conventional and high exhaust gas recirculation low-temperature combustion regimes. The work was conducted at a part-load cruise condition of 1500 r/min and at an indicated mean effective pressure of approximately 600 kPa. Exhaust gas recirculation rates were varied between 0% and 65% at absolute intake pressures of 100–150 kPa. Very low NO x emissions were achieved (<10 ppm, ∼0.05 g/kW h) for intake oxygen mass fractions below about 11%, independent of boost pressure. Smoke emission levels were lower than for non–exhaust gas recirculation combustion at oxygen mass fractions below ∼9%, depending on the boost pressure. High intake pressures reduced fuel consumption by 15% and combustion by-product emissions by 50%–60% compared to low boost. For the low intake boost case, little visible flame was apparent through borescope imaging. At higher boost pressures, intense flame luminosity was observed within the piston bowl early in the expansion stroke. Spatially averaged soot luminosity based on photomultiplier tube data showed that peak soot luminosity was five times greater and occurred 8 °CA earlier for high boost. This work demonstrates how the combination of appropriate boost pressures and exhaust gas recirculation rates can be used to mitigate the emissions and thermal efficiency penalties of high-dilution low-temperature combustion to achieve near-zero NO x operation.

scholarly journals Effects of intake-port throttling on combustion behaviour in diesel low-temperature combustion

2017 ◽  
Vol 19 (8) ◽  
pp. 827-838 ◽  
Author(s):  
Oluwasujibomi Sogbesan ◽  
Colin P Garner ◽  
Martin H Davy
Keyword(s):  
Low Temperature ◽  
Load Condition ◽  
Combustion Products ◽  
Hydrocarbon Emissions ◽  
Intake Port ◽  
Low Temperature Combustion ◽  
High Hydrocarbon ◽  
Low Load ◽  
Temperature Combustion ◽  
Port Throttling

This article describes the effects of intake-port throttling on diesel low-temperature combustion at a low and medium load condition. These conditions were known for their characteristically high hydrocarbon emissions predominantly from over-mixed and under-mixed mixture zones, respectively. The investigation was carried out to supplement current findings in the literature with valuable information on the formation of high hydrocarbon emissions with increasing swirl levels generated by intake-port throttling. This was achieved through the use of cycle-resolved high hydrocarbon measurements in addition to cycle averaged emissions and in-cylinder pressure-derived metrics. While there was negligible overall effect at the moderately dilute low-load conditions, increasing swirl has been shown to be beneficial to premixing efficacy under highly dilute conditions with extended ignition delay. This potential advantage was found to be nullified by the swirl-induced confinement of fuel and combustion products to the central region of the cylinder leading to poor late cycle burn rates and increased smoke emissions. High hydrocarbon emissions from the squish and head quench regions were reduced by an increase in swirl ratio.

Potential of in-cylinder exhaust gas recirculation stratification for combustion and emissions in diesel engines

2011 ◽  
Vol 226 (4) ◽  
pp. 547-559 ◽  
Author(s):  
W Park ◽  
S Lee ◽  
S Choi ◽  
K Min
Keyword(s):  
Low Temperature ◽  
Diesel Engines ◽  
Exhaust Gas Recirculation ◽  
Hydrocarbon Emissions ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Engine Simulation ◽  
Temperature Combustion ◽  
Soot Emissions ◽  
Gas Recirculation

It is difficult to decrease the emissions of nitrogen oxides (NO x) and soot simultaneously in conventional diesel engines. Low-temperature combustion concepts have been studied in an effort to overcome this problem. Low-temperature combustion has the potential to reduce NO x and soot emissions, but it has many limitations, including narrow operating ranges, high carbon monoxide and hydrocarbon emissions, and difficulties with ignition control. Exhaust gas recirculation (EGR) stratification is another combustion concept used to reduce NO x and soot emissions simultaneously using the local non-uniformity of EGR gas instead of increasing the overall EGR rate. In this study, the EGR stratification concept was improved using computational fluid dynamics. First, a two-step piston was developed to maximize the stratified EGR effects by obtaining a favourable EGR distribution pattern and injecting fuel into the high-EGR region. Then, the possibility of combustion and emission control using stratified EGR was estimated. The ideally distributed EGR in the cylinder results showed that the region of locally high EGR effectively influences the combustion characteristics and, thus, horizontally and centrally stratified EGR has the potential to reduce the nitric oxide (NO x) and soot emissions at the same time. Engine simulation results also showed simultaneous reductions in the NO x and the soot emissions.

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