Pyrometric imaging of soot processes in a pilot ignited direct injected natural gas engine

Khosravi, Mahdiar; McTaggart-Cowan, Gordon; Kirchen, Patrick

doi:10.1177/1468087420919196

Cited by 8 publications

(20 citation statements)

References 45 publications

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“…Further interaction between the pilot and NG jets may occur as the NG jets that have penetrated to the bowl wall are reflected and return toward the center of the combustion chamber. 12,19 Attributing quenching to individual processes is challenging, however the net effect on pilot ignition can be investigated using D(t ign ) (equation ( 5)). In Figure 9, the sensitivity of D(t ign ) to late-cycle NG injections is presented for four different RIT covering the three different NG premixing scenarios identified.…”

Section: Effects Ofmentioning

confidence: 99%

Heat release rate and emissions regimes of stratified pilot-ignited direct-injection natural gas combustion

Rochussen

McTaggart-Cowan

Kirchen

2021

International Journal of Engine Research

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Natural gas (NG) is an attractive fuel for heavy-duty internal combustion engines because of its potential for reduced CO2, particulate, and NOX emissions and lower cost of ownership. Pilot-ignited direct-injected NG (PIDING) combustion uses a small pilot injection of diesel to ignite a main direct injection of NG. Recent studies have demonstrated that increased NG premixing is a viable strategy to increase PIDING indicated efficiency and further reduce particulate and CO emissions while maintaining low CH4 emissions. However, it is unclear how the combustion strategies relate to one another, or where they fit within the continuum of NG stratification. The objective of this work is to present a systematic evaluation of pilot combustion, NG combustion, and emissions behavior of stratified-premixed PIDING combustion modes that span from fully-premixed to non-premixed conditions. A sweep of the relative injection timing, [Formula: see text], of NG and pilot diesel was performed in a heavy-duty PIDING engine with [Formula: see text] = 140–220 bar, [Formula: see text] = 0.47–0.71, and a constant NG energy fraction of 94%. Apparent heat release rate and emissions analyses identified interactions between the pilot fuel and NG, and qualitatively characterized the impact of NG stratification on combustion and emissions. Changes in the [Formula: see text] resulted in six distinct PIDING combustion regimes, for all considered injection pressures and equivalence ratios: (i) RIT-insensitive premixed, (ii) stratified-premixed (early-cycle injection), (iii) NG jet impingement transition, (iv) stratified-premixed (late-cycle injection), (v) variable premixed fraction, and (vi) minimally-premixed. Parametric definitions for the bounds of each regime of combustion were valid for the wide range of [Formula: see text] and [Formula: see text] investigated, and are expected to be relevant for other PIDING engines, as previously identified regimes agree with those identified here. This conceptual framework encompasses and validates the findings of previous stratified PIDING investigations, including optimal ranges of operation that provide significantly increased efficiency and lower emissions of incomplete combustion products.

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Section: Effects Ofmentioning

confidence: 99%

Heat release rate and emissions regimes of stratified pilot-ignited direct-injection natural gas combustion

Rochussen

McTaggart-Cowan

Kirchen

2021

International Journal of Engine Research

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“…The largest source of uncertainty for area-integrated two-colour pyrometry is the assumption that temperature and soot loading (KL factor) are homogeneous within the resolved area. Image-based spatially resolved methods overcome this by evaluating multiple small regions; the sensitivity and signal to noise ratio are dependent on the camera and the optical techniques used to align the two distinct wavelength measurements [36]. For spatially integrated systems, temperature and KL factor can vary significantly in the resolved region, and in fact significant areas of the field-of-view may not contain any radiating soot.…”

Section: Sources Of Uncertaintymentioning

confidence: 99%

“…As the LTC engine facility was not equipped to conduct spatially resolved pyrometry, data from an optically accessible engine with a similarly low-soot combustion was selected for comparison. This engine used a partially premixed, pilot-ignited direct injection of natural gas (PIDING) combustion process and has been extensively reported elsewhere [16,36,39]. The facility uses a Bowditch style extended piston with a quartz insert to image the entire combustion bowl [39].…”

Section: Spatially Resolved Vs Area Integrated Measurementsmentioning

confidence: 99%

“…To assess the applicability of this correction approach, ROIintegrated temperature and KL values have been calculated from the selected sequence of frames with between 17% and 97% sooting area in the PIDING engine. This sequence, shown in Figure 6, covers an ignition event where residual heat and radicals from a pilot diesel flame ignites a partially premixed cloud of natural gas (see [36]). The plot shows the T and KL values calculated from the raw integrated signal (integrated) and after correction for the sooting area.…”

Section: Spatially Resolved Vs Area Integrated Measurementsmentioning

confidence: 99%

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Two-Colour Pyrometry Measurements of Low-Temperature Combustion using Borescopic Imaging

Sarangi¹,

McTaggart-Cowan²,

Davy³

et al. 2021

SAE Technical Paper Series

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Low temperature combustion (LTC) of diesel fuel offers a path to low engine emissions of nitrogen oxides (NOx) and particulate matter (PM), especially at low loads. Borescopic optical imaging offers insight into key aspects of the combustion process without significantly disrupting the engine geometry. To assess LTC combustion, two-colour pyrometry can be used to quantify local temperatures and soot concentrations (KL factor). High sensitivity photo-multiplier tubes (PMTs) can resolve natural luminosity down to low temperatures with adequate signal-to-noise ratios. In this work the authors present the calibration and implementation of a borescope-based system for evaluating low luminosity LTC using spatially resolved visible flame imaging and high-sensitivity PMT data to quantify the luminous-area average temperature and soot concentration for temperatures from 1350-2600 K. The visible flame area is used to adjust the PMT measurements to account for sooting area (i.e., the fraction of the region of interest that contains discernible flame/natural luminosity). The validity of the approach is assessed using spatially resolved temperature and soot concentration data collected from a full optical single-cylinder engine operating using non-premixed natural gas combustion, with soot concentrations similar to those seen in the LTC data. The high sensitivity and low noise of the PMTs, combined with the broad field of view of the borescope, and the proposed sooting area correction method, provide robust measurement of flame temperature and KL factor in low temperature and low-sooting combustion conditions. Whilst the sooting area correction is found to have only a small effect on the measured temperature, it is shown to be important to provide soot concentrations that are representative of spatially resolved results. This work provides new insights into the use of relatively low-cost, high sensitivity PMTs to assess advanced and low-emission combustion systems.

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“…Several research groups in Canada, Japan and Europe have been working on the topic and have been able to demonstrate that methane emissions can be significantly reduced with the combustion process compared to classic natural gas engines. 3–7 Nevertheless, the combustion of natural gas still produces CO2 as combustion product. Therefor there is a need for fuels that do not contain carbon in their molecular structure.…”

Section: Introductionmentioning

confidence: 99%

Investigation of ammonia and hydrogen as CO2-free fuels for heavy duty engines using a high pressure dual fuel combustion process

Frankl

Gleis

Karmann

et al. 2020

International Journal of Engine Research

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This work is a numerical study of the use of ammonia and hydrogen in a high-pressure-dual-fuel (HPDF) combustion. The main fuels (hydrogen and ammonia) are direct injected and ignited by a small amount of direct injected pilot fuel. The fuels are injected using a dual fuel injector from Woodward L’Orange, which can induce two fuels independently at high pressures up to 1800 bar for the pilot fuel and maximum 500 bar for the main. The numerical CFD-model gets validated for of hydrogen-HPDF with experimental data. Due to safety issues at the test rig it was not possible to use ammonia in the experiments, so it is modelled using the numerical model. It is assumed that the CFD-model also gives qualitative correct results for the use of ammonia as main fuel, so a parameter study of ammonia-HPDF is made. The results for the hydrogen-HPDF show, that hydrogen can be used in the engine without any further modifications. The combustion is very stable, and the hydrogen ignites almost immediately when it enters the combustion chamber. The results of the ammonia combustion indicate, that the HPDF combustion mode can handle ammonia effectively. It seems beneficial to inject the ammonia at higher pressures than hydrogen. Also pre-heating the ammonia can increase the combustion efficiency.

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Pyrometric imaging of soot processes in a pilot ignited direct injected natural gas engine

Cited by 8 publications

References 45 publications

Heat release rate and emissions regimes of stratified pilot-ignited direct-injection natural gas combustion

Heat release rate and emissions regimes of stratified pilot-ignited direct-injection natural gas combustion

Two-Colour Pyrometry Measurements of Low-Temperature Combustion using Borescopic Imaging

Investigation of ammonia and hydrogen as CO2-free fuels for heavy duty engines using a high pressure dual fuel combustion process

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