M. F. Bardon

Improving the Fuel Economy of Stoichiometrically Fuelled S.I. Engines by Means of EGR and Enhanced Ignition - A Comparison of Gasoline, Methanol and Natural Gas

This paper describes an experimental study in which the potential for fuel economy improvements with EGR was investigated using an automotive V6 engine. Steady state engine dynamometer tests were run at 2,000 rpm and 200 kPa Brake Mean Effective Pressure (BMEP). The engine was fueled with gasoline, methanol or natural gas. Plasma jet ignition was evaluated as a means of improving EGR tolerance. EGR tolerance with methanol was found to be better than with gasoline, while natural gas showed the poorest EGR tolerance. Plasma jet ignition extended EGR limits for all three fuels. Fuel economy benefits were realized with natural gas and gasoline at low EGR rates and without EGR but plasma jet ignition provided no improvements with methanol until over 10% EGR was used. Plasma jet ignition made stable operation possible with methanol at 40% EGR, where fuel economy improvements were ultimately limited by the slow burning associated with the high EGR rate. Both slow burning and high cyclic variation affected gasoline at high EGR rates, while stability limits to spark advance with natural gas caused fuel economy to degrade at relatively low EGR rates.

Improving the Fuel Efficiency of Light-Duty Ethanol Vehicles - An Engine Dynamometer Study of Dedicated Engine Strategies

A machine for drilling and routing of printed circuit boards comprises a support mechanism for supporting a stack of superimposed boards in a support plane and for moving the stack of boards in a first predetermined direction parallel to the support plane. A tool spindle is disposed above the stack of boards and is movable in a second direction parallel to the support plane and perpendicular to the first direction, so that the positions of the holes to be drilled in the PC-boards can be determined in a coordinate system having the first and second directions as its X-axis and Y-axis respectively. For holding the stack of PC-boards pressed together during the drilling or routing operation, the machine comprises press rollers, which exert a pressure force upon the stack of PC-boards towards the support mechanism. The press rollers are arranged on both sides of the tool spindle with their axes of rotation parallel to the direction in which the tool spindle can be moved, i.e. the Y-direction.

Review of the Cold Starting Performance of Methanol and High Methanol Blends in Spark Ignition Engines: High Methanol Blends

This paper summarizes the results of a survey and analysis of cold starting data for spark ignition engines utilizing high methanol blends. All available published information, as well as additional data supplied by contributing agencies was considered. The report includes graphical comparisons of test results and a detailed discussion of the various factors which influence cold starting. Recommendations are made for further work needed to improve cold starting.

Volatility and flammability of methanol/gasoline blends

Computational procedures are described for combining a simple multicomponent fuel volatility model with flammability data to facilitate the analyses of a wide variety of practical situations involving methanol/gasoline blends. These include fire hazards, fuel droplet or film evaporation, ignition, combustion and engine cold starting

Cycle-by-Cycle Exhaust Temperature Monitoring for Detection of Misfiring and Combustion Instability in Reciprocating Engines

This paper describes a means of achieving cycle-by-cycle combustion monitoring of reciprocating engines without the use of cylinder pressure sensors. This approach is intended primarily for engines that are not equipped with indicator passages (that would facilitate the installation of cylinder pressure sensors) but are (or can be) equipped with fittings for individual cylinder exhaust thermocouples. The monitoring system uses rugged exhaust temperature probes and advanced signal processing and analysis to detect cycle-by-cycle variations in exhaust temperatures and correlates these with conventional combustion analysis parameters. The system is particularly useful for detecting the deteriorations in combustion stability that precede misfiring as well as individual misfire events if they occur. Engine test results are presented showing the correlation between the exhaust temperature signal and parameters based upon cylinder pressure measurements. The ability to detect low level combustion instability and isolated, individual misfires has been demonstrated on a 95 liter V12 industrial natural gas engine. It as also been shown that successful acquisition of high fidelity exhaust temperature signals for the combustion analysis can be achieved in the presence of the high levels of electromagnetic interference typical of a power generation facility.Copyright

A Vapour Pressure Model for Methanol/Gasoline M85 Blends

This paper presents an analytical model for M85 volatility behaviour. It uses a recently developed technique for gasoline volatility in conjunction with a modified form of Raoults Law corrected for non-ideality. Vapour pressure, methanol/gasoline distribution in the vapour phase and enthalpy of evaporation are all calculated using explicit equations. Constants needed for the equations are given for one M85 blend and a simple method of deriving them for any other gasoline/methanol mixture using only measured RVP is outlined. In addition to describing the new predictive technique, the paper gives the results of an experimental program in which vapour phase composition and vapour pressure behaviour were measured at various temperatures and vapour/liquid ratios.

A computational study of the flammability of methanol and gasoline fuel spills on hot engine manifolds

The fire hazards associated with gasoline and methanol are different because of the different physical and chemical properties of the fuels. In particular, the composition of the vapors they emit determines the comparative risk of a fire or explosion in cases of accidents or fuel leaks. This study compares the behavior of methanol and gasoline (n-octane) using mathematical models, so as to assist in determining whether there is an increased risk associated with the use of methanol fuels. The flammable zones surrounding a representative unconfined exhaust manifold were determined for methanol and n-octane at two manifold surface temperatures (700 and 1000 K) using computational fluid dynamics (CFD) techniques. Some of the CID computations were also confirmed experimentally. It was found that for a manifold surface temperature of 700 K, neither fuel would ignite, although the surface temperature is above the autoignition temperature for both fuels. At a surface temperature of 1000 K, it was found that each fuel could ignite and that this temperature would be near the minimum required for either fuel to be ignited by a hot surface. The predictions also confirm the experimentally observed phenomenon that real hot surface ignition temperatures are, generally, well above autoignition temperatures. It was concluded that the risk of spontaneous ignition is similar for both fuels for the type of leak scenario investigated (i.e. the risk with methanol is not significantly different than that of gasoline). The use of two-dimensional (2-D) steady-state CFD simulations can provide significant insight into the behavior of different fuels in what is generally a three-dimensional (3-D) transient phenomenon.

COLD STARTING PERFORMANCE OF GASOLINE/METHANOL M10 BLENDS IN A SPARK IGNITION ENGINE

Engine cold starting tests have been conducted in a laboratory cold chamber to compare the performance of three 10% methanol/90% gasoline blends with that of Indolene. The blends had different Reid Vapour Pressures and tests were conducted over a wide range of fuel/air ratios at temperatures as low as -45 deg C. It was found that all M10 blends tested had poorer starting performance than Indolene at cold temperatures, including those of nominally higher volatility. Cold starting did not correlate to Reid Vapour Pressure even when comparing two oxygenated fuels. Graphs are presented showing minimum cold starting temperature as a function of fuel-air equivalence ratio.

An Experimental Study of Spark Anemometry for In-Cylinder Velocity Measurements

It has been demonstrated by previous researchers that an approximate value of the bulk flow velocity through the spark plug gap of a running spark ignition engine may be deduced from the voltage and current waveforms of the spark. The technique has become known as spark anemometry and offers a robust means of velocity sensing for engine combustion chambers and other high temperature environments. This paper describes an experimental study aimed at improving performance of spark anemometry as an engine research tool. Bench tests were conducted using flow provided by a calibrated nozzle apparatus discharging to atmospheric pressure. Whereas earlier studies had relied upon assumptions about the shape of the stretching spark channel to relate the spark voltage to the flow velocity, the actual spark channel shape was documented using high speed video in the present study. A programmable ignition system was used to generate well-controlled constant current discharges. The spark anemometry apparatus was then tested in a light duty automotive engine. Results from the image analysis of the spark channel shape undertaken in the present study have shown that the spark kernel moves at a velocity of less than that of the free stream gas velocity. A lower velocity threshold exists below which there is no response from the spark. It is possible to obtain a consistent, nearly linear relationship between the first derivative of the sustaining voltage of a constant current spark and the free stream velocity if the velocity falls within certain limits. The engine tests revealed a great deal of cycle-to-cycle variation in the in-cylinder velocity measurements. Instances where the spark restrikes occur during the cycle must also be recognized in order to avoid false velocity indications.© 2006 ASME

Detection of Combustion Chamber Deposits in Diesel Engines Through Cylinder Pressure and Exhaust Temperature Measurements

This paper describes experimental research aimed at developing techniques for monitoring the growth of combustion chamber deposits in diesel engines using data obtained from cylinder pressure and exhaust temperature measurements. A naturally aspirated single cylinder research engine was operated alternately between low load “coking” conditions (2.5 bar BMEP) and higher load “decoking” conditions (5.5 bar BMEP) intended to promote the formation and removal, respectively of combustion chamber deposits. The polytropic exponent of compression was observed to increase during coking runs and decrease during decoking runs. The peak heat release rate was observed to decrease during coking runs and increase during decoking runs. The peak cycle value of the first derivative of the exhaust thermocouple signal decreased during coking runs but exhibited no clear trend during decoking runs. Conventional exhaust temperature measurements showed no consistent trend during coking runs but the exhaust temperature decreased during decoking runs.Copyright