Emissions Variability in Gaseous Fuel Direct Injection Compression Ignition Combustion

Author(s):  
Gregory D. Sullivan ◽  
Jian Huang ◽  
Timothy X. Wang ◽  
W. Kendal Bushe ◽  
Steven N. Rogak
Author(s):  
R Murugan ◽  
D Ganesh ◽  
G Nagarajan

Previous studies on reactivity controlled compression ignition combustion indicated that, reducing the hydrocarbon and carbon monoxide emissions at low load conditions still remains a challenge because of lower in-cylinder temperatures due to lower global reactivity gradient and reduced oxidation process. Research in this direction has not been reported so far and with this motivation, an attempt has been made to increase the global reactivity gradient and oxidation of fuel–air mixture by converting the low reactivity fuel methanol into medium reactivity fuel. This is achieved by mixing high octane oxygenated fuel, methanol (Octane Number: 110), with an oxygenated better cetane and volatility fuels like polyoxymethylene dimethyl ether (Cetane Number: 78) and isobutanol (Cetane Number: 15). The medium reactivity fuel with multiple direct injection of diesel fuel timed the combustion of dual fuel–air mixture to avoid too late or too advanced combustion which are the prime factors in controlling the unburnt emissions in a low temperature combustion process. Four medium reactivity fuel samples, M80IB20, M60IB40, M90P10, and M80P20, on percentage volume basis have been prepared and tested on the modified on-road three-cylinder turbocharged common rail direct injection diesel engine to demonstrate higher indicated thermal efficiency and potential reduction in unburnt and oxides of nitrogen/particulate matter emissions from reactivity controlled compression ignition combustion. Experimental results show that, use of medium reactivity fuel with optimized diesel injection strategy resulted in 66% decrease in hydrocarbon emission and 74% decrease in carbon monoxide emission by enhancing the oxidation of fuel–air mixture at lower temperatures which is evidently noticed in the combustion characteristics. Further reduction in hydrocarbon and carbon monoxide emission of about 90% has been achieved by integrating the diesel oxidation catalyst with the engine.


2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Jihad A. Badra ◽  
Jaeheon Sim ◽  
Ahmed Elwardany ◽  
Mohammed Jaasim ◽  
Yoann Viollet ◽  
...  

Gasoline compression ignition (GCI), also known as partially premixed compression ignition (PPCI) and gasoline direct injection compression ignition (GDICI), engines have been considered an attractive alternative to traditional spark ignition (SI) engines. Lean-burn combustion with the direct injection of fuel eliminates throttle losses for higher thermodynamic efficiencies, and the precise control of the mixture compositions allows better emission performance such as NOx and particulate matter (PM). Recently, low octane gasoline fuel has been identified as a viable option for the GCI engine applications due to its longer ignition delay characteristics compared to diesel and lighter evaporation compared to gasoline fuel (Chang et al., 2012, “Enabling High Efficiency Direct Injection Engine With Naphtha Fuel Through Partially Premixed Charge Compression Ignition Combustion,” SAE Technical Paper No. 2012-01-0677). The feasibility of such a concept has been demonstrated by experimental investigations at Saudi Aramco (Chang et al., 2012, “Enabling High Efficiency Direct Injection Engine With Naphtha Fuel Through Partially Premixed Charge Compression Ignition Combustion,” SAE Technical Paper No. 2012-01-0677; Chang et al., 2013, “Fuel Economy Potential of Partially Premixed Compression Ignition (PPCI) Combustion With Naphtha Fuel,” SAE Technical Paper No. 2013-01-2701). The present study aims to develop predictive capabilities for low octane gasoline fuel compression ignition (CI) engines with accurate characterization of the spray dynamics and combustion processes. Full three-dimensional simulations were conducted using converge as a basic modeling framework, using Reynolds-averaged Navier–Stokes (RANS) turbulent mixing models. An outwardly opening hollow-cone spray injector was characterized and validated against existing and new experimental data. An emphasis was made on the spray penetration characteristics. Various spray breakup and collision models have been tested and compared with the experimental data. An optimum combination has been identified and applied in the combusting GCI simulations. Linear instability sheet atomization (LISA) breakup model and modified Kelvin–Helmholtz and Rayleigh–Taylor (KH-RT) break models proved to work the best for the investigated injector. Comparisons between various existing spray models and a parametric study have been carried out to study the effects of various spray parameters. The fuel effects have been tested by using three different primary reference fuel (PRF) and toluene primary reference fuel (TPRF) surrogates. The effects of fuel temperature and chemical kinetic mechanisms have also been studied. The heating and evaporative characteristics of the low octane gasoline fuel and its PRF and TPRF surrogates were examined.


2017 ◽  
Vol 21 (1 Part B) ◽  
pp. 441-449
Author(s):  
Girish Bhiogade ◽  
Jiwak Suryawanshi

New combustion concepts have been recently developed with the purpose to tackle the problem of high emissions level of traditional direct injection Diesel engines. A good example is the premixed charge compression ignition combustion. A strategy in which early injection is used causing a burning process in which the fuel burns in the premixed condition. In compression ignition engines, soot (particulate matter) and NOx emissions are an extremely unsolved issue. Premixed charge compression ignition is one of the most promising solutions that combine the advantages of both spark ignition and compression ignition combustion modes. It gives thermal efficiency close to the compression ignition engines and resolves the associated issues of high NOx and particulate matter, simultaneously. Premixing of air and fuel preparation is the challenging part to achieve premixed charge compression ignition combustion. In the present experimental study a diesel vaporizer is used to achieve premixed charge compression ignition combustion. A vaporized diesel fuel was mixed with the air to form premixed charge and inducted into the cylinder during the intake stroke. Low diesel volatility remains the main obstacle in preparing premixed air-fuel mixture. Exhaust gas re-circulation can be used to control the rate of heat release. The objective of this study is to reduce exhaust emission levels with maintaining thermal efficiency close to compression ignition engine.


2016 ◽  
Vol 18 (7) ◽  
pp. 657-676 ◽  
Author(s):  
Prasad S Shingne ◽  
Robert J Middleton ◽  
Dennis N Assanis ◽  
Claus Borgnakke ◽  
Jason B Martz

This two-part article presents a model for boosted and moderately stratified homogeneous charge compression ignition combustion for use in thermodynamic engine cycle simulations. The model consists of two components: one an ignition model for the prediction of auto-ignition onset and the other an empirical combustion rate model. This article focuses on the development and validation of the homogeneous charge compression ignition model for use under a broad range of operating conditions. Using computational fluid dynamics simulations of the negative valve overlap valve events typical of homogeneous charge compression ignition operation, it is shown that there is no noticeable reaction progress from low-temperature heat release, and that ignition is within the high-temperature regime ( T > 1000 K), starting within the highest temperature cells of the computational fluid dynamics domain. Additional parametric sweeps from the computational fluid dynamics simulations, including sweeps of speed, load, intake manifold pressures and temperature, dilution level and valve and direct injection timings, showed that the assumption of a homogeneous charge (equivalence ratio and residuals) is appropriate for ignition modelling under the conditions studied, considering the strong sensitivity of ignition timing to temperature and its weak compositional dependence. Use of the adiabatic core temperature predicted from the adiabatic core model resulted in temperatures within ±1% of the peak temperatures of the computational fluid dynamics domain near the time of ignition. Thus, the adiabatic core temperature can be used within an auto-ignition integral as a simple and effective method for estimating the onset of homogeneous charge compression ignition auto-ignition. The ignition model is then validated with an experimental 92.6 anti-knock index gasoline-fuelled homogeneous charge compression ignition dataset consisting of 290 data points covering a wide range of operating conditions. The tuned ignition model predictions of [Formula: see text] have a root mean square error of 1.7° crank angle and R2 = 0.63 compared to the experiments.


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