Vapour Space Flammability Considerations for Gasoline Compression Ignition Vehicles Operating on “Dieseline” Blends.

Vapour Space Flammability Considerations for Gasoline Compression Ignition Vehicles Operating on “Dieseline” Blends.

Type	Web Page
URL	http://papers.sae.org/2016-01-2266/
Abstract	Gasoline Compression Ignition (GCI) technology can provide both high efficiency and relatively low engine-out emissions. The introduction of any new vehicle technology requires widespread availability of appropriate fuels. Consequently, it would be ideal if GCI vehicles were able to operate using the standard grade of gasoline. However, operation at idle and low loads remains a challenge, due to the relatively low autoignition reactivity of conventional gasoline at these conditions. One solution would be to use both diesel and gasoline, either in separate tanks or blended as a single fuel, i.e., dieseline. A major concern for dieseline is whether a flammable mixture can exist in the vapor space in the fuel tank. In a practical scenario, the ambient temperature would generally exceed the Lower Flammability Limit (LFL) temperature of diesel/gasoline blends. A non-flammable vapor could still be assured, however, if the temperature in the fuel tank were above the Upper Flammability Limit (UFL) temperature. To investigate whether a flammable mixture could exist, researchers examined the Upper Flammability Limit (UFL) temperatures of 12 distinct blends of gasoline, diesel, ethanol and ETBE in a special combustion chamber designed to mimic a vehicle tank, with a 5% fuel fill level to represent expected worst case conditions. Results suggest that under realistic assumptions of gasoline DVPE and ambient temperature, nonflammable blends can be achieved with mixtures containing a minimum of 25-40% gasoline. Derived Cetane Numbers up to 36-40 could be achieved, making the fuels suitable for Low Temperature Combustion.

Prediction of research octane number in catalytic naphtha reforming unit of Shazand Oil Refinery

Prediction of research octane number in catalytic naphtha reforming unit of Shazand Oil Refinery

Type	Journal Article
Author	Abdolreza Moghadassi
Author	Alireza Beheshti
URL	http://www.inderscienceonline.com/doi/abs/10.1504/IJISE.2016.077696
Volume	23
Issue	4
Pages	435-447
Publication	International Journal of Industrial and Systems Engineering
Date	January 1, 2016
Abstract	Authors created an artificial neural network model to predict the research octane number of an industrial catalytic naphtha reforming unit. The required data set was obtained from Shazand Oil Refinery. The H2/HC ratio, feed flow rate, pressure, specific gravity and ASTM D-86 distillation data of the feed stream were employed as input variables. A variety of neural networks were trained and tested to determine the best ANN model. They found a three-layer network including two hidden layers with minimum mean square error of 0.28 for testing. Comparison between estimated and experimental values of octane number displayed good agreement. Results demonstrate the capability of ANN model to predict the octane number of a typical catalytic naphtha reforming unit with an acceptable error. Accordingly, the ANN model can be applied in other similar units for octane number prediction.

Physical and chemical effects of low octane gasoline fuels on compression ignition combustion

Physical and chemical effects of low octane gasoline fuels on compression ignition combustion

Type	Journal Article
Author	Jihad Badra
Author	Yoann Viollet
URL	http://www.sciencedirect.com/science/article/pii/S0306261916313629
Volume	183
Pages	1197-1208
Publication	Applied Energy
Date	December 1, 2016
Abstract	Gasoline compression ignition (GCI) engines running on low octane gasoline fuels are a promising alternative to traditional spark ignition engines. Researchers investigated three fuels with differing chemical and physical characteristics in single cylinder engine running in GCI combustion mode at part-load conditions both experimentally and numerically. The fuels were: Saudi Aramco light naphtha (SALN) (Research octane number, Haltermann straight run naphtha and a primary reference fuel. Injection sweeps, where the start of injection (SOI) is changed between −60 and −11 CAD aTDC, were conducted for the three fuels. Full cycle computational fluid dynamics (CFD) simulations were executed using PRFs as chemical surrogates for the naphtha fuels. Physical surrogates based on the evaporation characteristics of the naphtha streams were developed. Their properties were implemented in the engine simulations. Researchers observed that the three fuels have similar combustion phasings and emissions at test conditions, with minor differences at SOI earlier than −30 CAD aTDC. The trends were reproduced by the CFD calculations. The chemical and physical effects were investigated numerically. Researchers found that the physical characteristics of the fuel significantly affect the combustion for injections earlier than −30 CAD aTDC because of the low evaporation rates of the fuel because of the higher boiling temperature of the fuel and the colder in-cylinder air during injection.