Spectroscopic Measurements of Low-Temperature Heat Release for Homogeneous Combustion Compression Ignition (HCCI)n-Heptane/Alcohol Mixture Combustion

2010 ◽  
Vol 24 (10) ◽  
pp. 5404-5409 ◽  
Author(s):  
Peerawat Saisirirat ◽  
Fabrice Foucher ◽  
Somchai Chanchaona ◽  
Christine Mounaïm-Rousselle
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Compression Ignition ◽  
Spectroscopic Measurements ◽  
Alcohol Mixture ◽  
Temperature Heat ◽  
Homogeneous Combustion

CFD Analysis of Diesel-Methane Dual Fuel Low Temperature Combustion at Low Load and High Methane Substitution

2018 ◽  
Author(s):  
Andrea Aniello ◽  
Lorenzo Bartolucci ◽  
Stefano Cordiner ◽  
Vincenzo Mulone ◽  
Sundar R. Krishnan ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Diesel Fuel ◽  
Single Stage ◽  
Dual Fuel ◽  
Low Temperature Combustion ◽  
Two Stage ◽  
Low Load ◽  
Temperature Heat ◽  
Temperature Combustion

Over the last few decades, emissions regulations for internal combustion engines have become increasingly restrictive, pushing researchers around the world to exploit innovative propulsion solutions. Among them, the dual fuel low temperature combustion (LTC) strategy has proven capable of reducing fuel consumption and while meeting emissions regulations for oxides of nitrogen (NOx) and particulate matter (PM) without problematic aftertreatment systems. However, further investigations are still needed to reduce engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions as well as to extend the operational range and to further improve the performance and efficiency of dual-fuel engines. In this scenario, the present study focuses on numerical simulation of fumigated methane-diesel dual fuel LTC in a single-cylinder research engine (SCRE) operating at low load and high methane percent energy substitution (PES). Results are validated against experimental cylinder pressure and apparent heat release rate (AHRR) data. A 3D full-cylinder RANS simulation is used to thoroughly understand the influence of the start of injection (SOI) of diesel fuel on the overall combustion behavior, clarifying the causes of AHRR transition from two-stage AHRR at late SOIs to single-stage AHRR at early SOIs, low temperature heat release (LTHR) behavior, as well as high HC production. The numerical campaign shows that it is crucial to reliably represent the interaction between the diesel spray and the in-cylinder charge to match both local and overall methane energy fraction, which in turn, ensures a proper representation of the whole combustion. To that aim, even a slight deviation (∼3%) of the trapped mass or of the thermodynamic conditions would compromise the numerical accuracy, highlighting the importance of properly capturing all the phenomena occurring during the engine cycle. The comparison between numerical and experimental AHRR curves shows the capability of the numerical framework proposed to correctly represent the dual-fuel combustion process, including low temperature heat release (LTHR) and the transition from two-stage to single stage AHRR with advancing SOI. The numerical simulations allow for quantitative evaluation of the residence time of vapor-phase diesel fuel inside the combustion chamber and at the same time tracking the evolution of local diesel mass fraction during ignition delay — showing their influence on the LTHR phenomena. Oxidation regions of diesel and ignition points of methane are also displayed for each case, clarifying the reasons for the observed differences in combustion evolution at different SOIs.

Low temperature heat release in amorphous Fe80B14Si6

1986 ◽  
Vol 57 (6) ◽  
pp. 425-426 ◽  
Author(s):  
M. Koláč ◽  
B.S. Neganov ◽  
A. Sahling ◽  
S. Sahling
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Temperature Heat

Modeling the Effects of Steam-Fuel Reforming Products on Homogeneous Charge Compression Ignition of n-Heptane

2009 ◽  
Author(s):  
Francisco Posada ◽  
Nigel N. Clark ◽  
Aleksandr Kozlov ◽  
Martin Linck ◽  
Dmitri Boulanov ◽  
...  
Keyword(s):  
Species Composition ◽  
Heat Release ◽  
Homogeneous Charge Compression Ignition ◽  
Zone Model ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Fuel Reforming ◽  
Total N ◽  
Temperature Heat ◽  
Homogeneous Charge

Homogeneous Charge Compression Ignition (HCCI) offers benefits of high efficiency with low emissions, but suffers load range limitations and control issues. A method to improve control of HCCI was numerically investigated based on two separate fuel streams with different autoignition characteristics to regulate timing and heat release at specific operational conditions. In this numerical study n-heptane was selected as the primary fuel, and the secondary fuel was defined as a reformed product of n-heptane (RG). The reformed fuel species composition was experimentally determined based on steam/n-heptane reforming process at a steam/carbon mole ratio of 2:1. In addition to H2 and CO, the reformed fuel stream was composed of CH4, CO2, H2O and non-reformed n-heptane. A single zone model using a detailed chemical kinetic mechanism was implemented on CHEMKIN to study the effects of base fuel and steam-fuel reforming products on the ignition timing and heat release characteristics. The study was performed considering the reformed fuel species composition at total n-heptane conversion (stoichiometric) and also at the composition corresponding to a specific set of operational reforming temperatures. The computational model confirmed that the reformed products have a strong influence on the low temperature heat release (LTHR) region, affecting the onset of the high temperature heat release (HTHR). The ignition timing was proportionally delayed with respect to the baseline fuel case when higher concentrations of reformed gas were used.

Operating Limits of Spark-Assisted Compression Ignition Combustion Under Boosted Ultra-EGR Dilute Conditions in a Negative Valve Overlap Engine

2019 ◽  
Author(s):  
Vassilis Triantopoulos ◽  
Jason B. Martz ◽  
Jeff Sterniak ◽  
George Lavoie ◽  
Dennis N. Assanis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Engine Speed ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Operating Limits

Abstract Spark-assisted compression ignition (SACI) is a low temperature combustion mode that can offer thermal efficiency improvements and lower nitrogen oxide emissions compared to conventional spark-ignited combustion. However, the SACI operating range is often limited due to excessive pressure rise rates driven by rapid heat release rates. Well-controlled experiments were performed to investigate the SACI operating limits under previously unexplored boosted, stoichiometric, EGR dilute conditions, where low temperature combustion engines promise high thermodynamic efficiencies. At higher intake boost, the SACI high load limit shifted towards lower fuel-to-charge equivalence ratio mixtures, creating a larger gap between the conventional spark-ignition EGR dilution limit and the boosted SACI operating limits. Combustion phasing retard was very effective at reducing maximum pressure rise rate levels until the stability limit, primarily due to slower end-gas burn rates. Gross fuel conversion efficiency improvements up to 10% were observed by using intake boost for either load expansion or dilution extension. Changes in engine speed necessitated changes in unburned gas temperature to match autoignition timing, but were shown to have negligible impact on the heat release profile on a crank angle basis. Lower engine speeds were favorable for load expansion, as time-based peak pressure rise rates scaled with engine speed.

Investigation of Low Temperature Combustion Regimes of Biodiesel With n-Butanol Injected in the Intake Manifold of a Compression Ignition Engine

2012 ◽  
Author(s):  
Valentin Soloiu ◽  
Marvin Duggan ◽  
Henry Ochieng ◽  
David Williams ◽  
Gustavo Molina ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Combustion Chamber ◽  
Nox Reduction ◽  
Intake Manifold ◽  
Power Stroke ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Temperature Combustion

In this study, the in-cylinder soot and NOx trade off was investigated in a Compression Engine by implementing Premixed Charge Compression Ignition (PCCI) coupled with Low Temperature Combustion (LTC) for selected regimes of 1–3 bars IMEP. In order to achieve that, an omnivorous (multi-fuel) single cylinder diesel engine was developed by injecting n-butanol in the intake port while being fueled with biodiesel by direct injection in the combustion chamber. By applying this methodology, the in-cylinder pressure decreased by 25% and peak pressure was delayed in the power stroke by about 8 CAD for the cycles in which the n-butanol was injected in the intake manifold at the engine speed of 800 rpm and low engine loads, corresponding to 1–3 bars IMEP. Compared with the baseline taken with ultra-low sulfur diesel no. 2 (USLD#2), the heat release presented a more complex shape. At 1–2 bars IMEP, the premixed charge stage of the combustion totally disappeared and a prolonged diffusion stage was found instead. At 3 bars IMEP, an early low temperature heat release was present that started 6 degrees (1.25 ms) earlier than the diesel reference heat release with a peak at 350 CAD corresponding to 1200 K. Heat losses from radiation of burned gas in the combustion chamber decreased by 10–50% while the soot emissions showed a significant decrease of about 98%, concomitantly with a 98% NOx reduction at 1 IMEP, and 77% at 3 IMEP, by controlling the combustion phases. Gaseous emissions were measured using an AVL SESAM FTIR and showed that there were high increases in CO, HC and NMHC emissions as a result of PCCI/LTC strategy; nevertheless, the technology is still under development. The results of this work indicate that n-butanol can be a very promising fuel alternative including for LTC regimes.

Low temperature heat release, sound velocity and attenuation, specific heat and thermal conductivity in polymers

1995 ◽  
Vol 98 (5-6) ◽  
pp. 517-547 ◽  
Author(s):  
A. Nittke ◽  
M. Scherl ◽  
P. Esquinazi ◽  
W. Lorenz ◽  
Junyun Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Specific Heat ◽  
Heat Release ◽  
Sound Velocity ◽  
Temperature Heat
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