D. P. Gardiner

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.

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

Investigation of Flame Acceleration Enhancement for a Pulse Detonation Engine Initiation System

This paper reports on the investigation of a novel method for detonation initiation that can be used for a Pulse Detonation Engine (PDE). A common method used to initiate a detonation wave is via flame acceleration, this initiation mode is known as deflagration-to- detonation transition (DDT). Rapid flame acceleration in a tube is achieved by the use of repeated orifice plates to produce turbulence in the unburned gas flow ahead of the flame. Previous studies in fuel-air mixtures have shown that flame acceleration obtained in a classically configured orifice plate laden tube, i.e., uniformly spaced and sized orifice plates with one end igniter, results in a detonation run-up distance which is too long for a PDE application. The objective of the present investigation is to enhance the flame acceleration process that leads to DDT by using multi-point ignition. Experiments were performed in a 3.05 m long, 15.2 cm inner-diameter tube equipped with a primary igniter mounted centrally on the tube endplate. Equally spaced orifice plates with blockage ratio of 0.43 were placed in the first 2 m of the tube. A bank of four circumferentially equally spaced automotive spark plugs are located after each of the first six orifice plates. The firing time of each igniter bank is controlled by an electronic circuit. The concept is that each spark initiates a flame ball thereby augmenting the flame area, and hence the volumetric burning rate, relative to that obtained using one igniter located at the endplate. The results indicate that flame acceleration is augmented early in the tube and maintained to the end. The reduction in the distance required for the flame to accelerate to a velocity on the order of the speed of sound in the combustion products is modest, on the order of 10%. However, the reduction in the time required to reach this velocity is much more pronounced which has an impact on the PDE cycle frequency.

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.

Development of a Spark Discharge PM Sensor for Measurement of Engine-Out Soot Emissions

Filter paper methods are well recognized as an effective means of measuring soot emissions from diesel engines. However, these methods provide an average soot value over a relatively long time period, rather than a real-time signal. Real-time measurements of engine-out soot emissions that could track changes in soot levels during transient operating conditions would be useful for the optimization of engine control strategies such as exhaust gas recirculation. This paper presents experimental results obtained using a real-time PM sensor based upon a spark discharge measuring principle. Like traditional filter paper devices, it is sensitive to the carbon or soot component of the particulate matter emitted by diesel engines. The sensor was tested on a turbocharged diesel engine, and compared with reference measurements of Filter Smoke Number (FSN) from an AVL 415s smokemeter. Improvements to the sensor made it possible to measure soot levels at FSN values over 3.5, while retaining good sensitivity below FSN values of 0.1. The sensor signal showed a high correlation with the reference FSN measurements. This correlation was used to develop a signal processing technique so the sensor provided a real-time signal for predicted FSN. Conversion of the FSN values to mass concentration values (using published techniques for the reference instrument) indicated that the output of the spark discharge soot sensor was nearly linear with mass concentration over a substantial portion of the measuring range. The sensor showed a response time of under 2 seconds to step changes in FSN levels.© 2010 ASME

Emissions Testing From the Use of Various Biodiesel Blends in Representative Canadian Army Equipment

A comprehensive series of emissions measurements were taken from two pieces of equipment used by the Canadian Forces. A field kitchen burner unit and the engine from the Light Armoured Vehicle III (LAVIII) were operated using two base fuels: low and ultra low sulphur diesel fuel blended with three different biofuels. Methylesters from canola, tallow and yellow grease were mixed in a range of volumetric proportions from 0 to 20%. Additionally, both very low sulphur diesel and aviation turbine fuel (JP-8) were tested against neat low sulphur diesel fuel. The complete chemical analysis conducted on all test fuels will not be presented here. A full range of gaseous emission measurements were obtained including oxides of nitrogen, unburnt hydrocarbons, carbon monoxide and dioxide and limited sulphur dioxide measurements. Two means of monitoring particulate matter were used with one proving to be more effective than the other. Novel techniques were used to obtain the burner unit emissions results and the AVL 8-mode test sequence was applied to the Caterpillar engine from the LAVIII. Although emission trends were detected, levels were often on the margins of perceptibility of the gas analysis system, and atmospheric conditions were challenging. Nevertheless, a methodology was developed and refined. Some correlations were made between the chemical analysis and emissions results. The testing will allow the Canadian Army to estimate its emissions footprint.Copyright

Evaluation of a Spark Discharge Particulate Matter Sensor in a Turbocharged Diesel Engine

This paper describes an experimental study of a Particulate Matter (PM) sensor that is intended for on-board control and diagnostic applications in diesel engines. The sensor measures the exhaust PM concentration based upon changes in the voltage waveform of a repetitive, low energy spark discharge. The sensor is electrically heated to prevent carbon fouling from diesel soot and to control its operating temperature. Earlier versions of the sensor were installed directly in the engine exhaust pipe like an Exhaust Gas Oxygen sensor. It was determined that the output of the PM sensor was sensitive to temperature as well as PM concentration, and variations in exhaust temperature made it difficult to maintain the sensor at a constant temperature. In the present study, the sensor was mounted in an electrically heated chamber and a portion of the engine exhaust was bypassed through the chamber. This made it possible to improve the stability of the sensor temperature, thereby reducing the sensitivity of the PM indication to changes in exhaust temperature as the engine load was varied. The PM sensor has been evaluated using a Caterpillar Model 3126 turbocharged 6-cylinder medium duty diesel engine. Small changes in load were used to create minor variations in exhaust PM levels. The PM levels were measured using an AVL 415S smoke meter. Experimental results are presented showing the correlation between the PM sensor signal and the reference PM measurements and the impact of speed and load variations on the correlation.© 2007 ASME

Flame-Out Detection for Gas Turbine Engines Based Upon Thermocouple Signal Analysis

This paper describes an experimental study to examine the potential of using Exhaust Gas Temperature (EGT) thermocouples for prompt flame-out detection in gas turbine engines. The approach taken involved accelerating the response of a shielded, slow response thermocouple using electronic processing of the signal. Thus, the abrupt drop in temperature characteristic of a flame-out could be detected within a much shorter time period than would be possible through a conventional thermocouple temperature measurement method. This was intended to provide a robust alternative to existing optical flame-out sensors which have fast response but can be susceptible to false flame-out indications due to window sooting. A production EGT thermocouple with online electronic processing was compared with a production optical flame sensor from a GE F-404 and a laboratory photodiode sensing system. The devices were tested in a full scale GE J-85 combustion chamber sector rig with optical access. The results showed that the thermocouple flame sensor had a response time to flame-outs of less than 100 ms. This was much faster than a conventional thermocouple, but still an order of magnitude longer than the optical flame sensor. However, whereas the optical flame sensor could yield ambiguous results about the presence of flame under some conditions, the thermocouple flame sensor provided a clear indication of flame-out events for all the conditions that were tested.Copyright