Search Results

The method of flame ionization was used for measuring total hydrocarbons in both single-cylinder and multicylinder 4-cycle, direct injection diesel engine exhaust. Use of the emission parameters of hydrocarbon concentration, per cent unburned fuel, specific hydrocarbon rate, mass of hydrocarbons per million cycles, mass of hydrocarbons per mile, and mass of hydrocarbons per ton-mile are discussed. The basic approach used in the flame ionization detector is shown. The hydrocarbon sample was transferred from the exhaust system through a heated sample line and oven operating at 375 F. The sample line was aspirated to reduce the sample residence time to 2 sec. The effect various sampling locations have on hydrocarbon measurements from a single-cylinder engine is shown and discussed. The effects of load, speed, and injection timing on hydrocarbon emission data are shown for a single-cylinder engine.

In a Spark-Ignited engine, there will come a point, as load is increased, where the unburned air-fuel mixture undergoes auto-ignition (knock). The onset of knock represents the upper limit of engine output, and limits the extent of engine downsizing / boosting that can be implemented for a given application. Although effective at mitigating knock, requiring high octane fuel is not an option for most markets. Retarding spark timing can extend the high load limit incrementally, but is still bounded by limits for exhaust gas temperature, and spark retard results in a notable loss of efficiency. Likewise, enriching the air-fuel mixture also decreases efficiency, and has profound negative impacts on engine out emissions. In this current work, a Direct-Injected, Boosted, Spark-Ignited engine with Variable Valve Timing was tested under steady state high load operation. Comparisons were made among three fuels; an 87 AKI, a 91 AKI, and a 110 AKI off-road only race fuel.

The present study investigates the pressure drop and filtration characteristics of wall-flow diesel particulate monoliths, with the aid of a mathematical model. An analytic solution to the model equations describing exhaust gas mass and momentum conservation, in the axial direction of a monolith cell, and pressure drop across its porous walls has been obtained. The solution is in very good agreement with available experimental data on the pressure drop of a typical wall-flow monolith. The capture of diesel particles by the monolith, is described applying the theory of filtration through a bed of spherical collectors. This simple model, is in remarkable agreement with the experimental data, collected during the present and previous studies, for the accumulation mode particles (larger than 0.1 μm).

Heavy-duty diesel engine particulate matter (PM) emissions must be reduced from 0.1 to 0.01 grams per brake horsepower-hour by 2007 due to EPA regulations [1]. A catalyzed particulate filter (CPF) is used to capture PM in the exhaust stream, but as PM accumulates in the CPF, exhaust flow is restricted resulting in reduced horsepower and increased fuel consumption. PM must therefore be burned off, referred to as CPF regeneration. Unfortunately, nominal exhaust temperatures are not always high enough to cause stable self-regeneration when needed. One promising method for active CPF regeneration is to inject fuel into the exhaust stream upstream of an oxidation catalytic converter (OCC). The chemical energy released during the oxidation of the fuel in the OCC raises the exhaust temperature and allows regeneration.

A study of the sources of variability in particulate measurements using the Heavy-Duty Transient Test (40 CFR Subpart N) has been conducted. It consisted of several phases: a critical examination of the test procedures, visits to representative facilities to compare and contrast facility designs and test procedures, and development of a simplified model of the systems and procedures used for the Heavy-Duty Transient Test. Some of the sources of variability include; thermophoretic deposition of particulate matter onto walls of the sampling system followed by subsequent reentrainment in an unpredictable manner, the influence of dilution and cooling upon the soluble organic fraction, inconsistency among laboratories in the engine and dynamometer control strategies, and errors in measurements of flows into and out of the secondary dilution tunnel.

Numerical modeling of fuel injection in internal combustion engines in a Lagrangian framework requires the use of a spray-wall interaction sub-model to correctly assess the effects associated with spray impingement. The spray impingement dynamics may influence the air-fuel mixing and result in increased hydrocarbon and particulate matter emissions. One component of a spray-wall interaction model is the splashed mass fraction, i.e. the amount of mass that is ejected upon impingement. Many existing models are based on relatively large droplets (mm size), while diesel and gasoline sprays are expected to be of micron size before splashing under high pressure conditions. It is challenging to experimentally distinguish pre- from post-impinged spray droplets, leading to difficulty in model validation.

Single droplet theory is used to simulate the behavior of fuel sprays in high-speed open-chamber diesels. A model for sprays in still air is presented which includes the air motion induced by the spray. Calculated paths and vaporization histories for droplets injected into swirling air are also presented. It is shown that the paths of vaporizing drops are closely approximated by solid sphere calculations. The effects of swirl speed, engine rpm, and squish air motion are also investigated.

While significant progress has been made in recent years to develop hybrid and battery electric vehicles for passenger car and light-duty applications to meet future fuel economy targets, the application of hybrid powertrains to heavy-duty truck applications has been very limited. The relatively lower energy and power density of batteries in comparison to diesel fuel and the operating profiles of most heavy-duty trucks, combine to make the application of hybrid powertrain for these applications more challenging. The high torque and power requirements of heavy-duty trucks over a long operating range, the majority of which is at constant cruise point, along with a high payback period, complexity, cost, weight and range anxiety, make the hybrid and battery electric solution less attractive than a conventional powertrain.

The Vehicle Engine Cooling System Simulation (VECSS) computer code has been developed at the Michigan Technological University to simulate the thermal response of a cooling system for an on-highway heavy duty diesel powered truck under steady and transient operation. In Part 1 of this research, the code development and verification has been presented. The revised and enhanced VECSS (version 8.1) software is capable of simulating in real-time a Freightliner FLD 120 truck with a Detroit Diesel Series 60 engine, Behr McCord radiator, Allied signal / Garrett Automotive charge air cooler and turbocharger, Kysor DST variable speed fan clutch, DDC oil and coolant thermostat. Other cooling system components were run and compared with experimental data provided by Kysor Cooling Systems. The experimental data were collected using the Detroit Diesel Electronic Control's (DDEC) Electronic Control Module (ECM) and the Hewlett Packard (HP) data acquisition system.

The Vehicle Engine Cooling System Simulation (VECSS) computer code has been developed at the Michigan Technological University to simulate the thermal response of the cooling system of an on-highway heavy duty diesel powered truck under steady and transient operation. This code includes an engine cycle analysis program along with various components for the four main fluid circuits for cooling air, cooling water, cooling oil, and intake air, all evaluated simultaneously. The code predicts the operation of the response of the cooling circuit, oil circuit, and the engine compartment air flow when the VECSS is operated using driving cycle data of vehicle speed, engine speed, and fuel flow rate for a given ambient temperature, pressure and relative humidity.

Enhanced VECSS simulation program was tested for use as a cooling system design tool. The design parameters indicated in the study were varying fan type, fan speed, engine power rating, radiator style and air conditioning condenser. The predicted temperature results were compared to the experimental data, and were found to follow the measured trends, and in cases when the exact parameters were simulated, were found to match the temperature amplitudes.

A one-dimensional incompressible flow model covering the mechanisms involved in the airflow through an automotive radiator-shroud-fan system with no heat transfer was developed. An analytical expression to approximate the experimentally determined fan performance characteristics was used in conjunction with an analytical approach for this simplified cooling airflow model, and the solution is discussed with illustrations. A major result of this model is a closed form equation relating the transient velocity of the air to the vehicle speed, pressure rise characteristics and speed of the fan, as well as the dimensions and resistance of the radiator. This provides a basis for calculating cooling airflow rate under various conditions. The results of the incompressible flow analysis were further compared with the computational results obtained with a previously developed one-dimensional, transient, compressible flow model.

A study was undertaken to investigate the affect of exhaust gas recirculation (EGR) on engine wear and lubricating oil degradation in a heavy duty diesel engine using a newly developed methodology that uses analytical ferrography in conjunction with short term tests. Laboratory engine testing was carried out on a Cummins NTC-300 Big Cam II diesel engine at rated speed (1800 RPM) and 75% rated load with EGR rates of 0, 5, and 15% using a SAE 15W40 CD/SF/EO-K oil. Dynamometer engine testing involved collecting oil samples from the engine sump at specified time intervals through each engine test. These oil samples were analyzed using a number of different oil analysis techniques that provide information on the metal wear debris and also on the lubricating oil properties. The results from these oil analysis techniques are the basis of determining the effect of EGR on engine wear and lubricating oil degradation, rather than an actual engine tear down between engine tests.

The techniques used to characterize the chemical and physical nature of particulates in diesel exhaust emissions are reviewed. The emphasis is on understanding the broader aspects of the fundamental nature of not only diesel particulates, but particulate systems in general. Consideration is given to the special nature of particulates which make them significant pollutants and to the relative place of the diesel in the formation of man-made particles. The underlying combustion processes leading to carbon and sulfur based particulates are reviewed. The important variables in steps of the combustion processes which lead to particulate formation are considered, as well as major fuel and engine factors. Collection methods are examined with examples given from current diesel dilution techniques. Probes, sampling lines, and instrumentation are considered.

A diesel exhaust sampling system was specially designed to measure and collect emissions from a ceramic wall-flow particulate trap during periods of controlled electric regeneration with the exhaust emissions bypassing the trap. This resulted in the regeneration emissions being independent of those produced during either baseline (no control) or trap (exhaust filtration) sampling conditions. This system provided data regarding the physical, chemical, and biological character of regeneration emissions relative to baseline and trap emissions. Selected emission levels measured continuously during the regeneration process were also used to define the particle combustion process in the trap core. Variations in hydrocarbons (HC), oxides of nitrogen (NOx), and particulate volume concentrations during the regeneration process were used to define four stages of the combustion process: preheat; combustion wave formation; combustion wave propagation; and combustion wave extinction.

One of the more objectionable aspects of the use of the diesel engine is its emission of particulate matter. Methods for collecting particulate matter samples in the undiluted exhaust gases with an Andersen Impactor for gravimetric and electron microscopy analysis are developed. A direct injection Vee-eight naturally aspirated diesel engine was used in the study. This paper presents the results of an in-depth study of the physical characteristics of diesel particles. The size distribution of the particulate matter was obtained using an Andersen Inertial Impactor for the engine conditions applicable to the SAE 13-mode cycle. The particulate matter was analyzed using both scanning and transmission electron microscopes and was found to be comprised of individual spherical particles ranging from 100 ņ to 800 Å with a mean size of approximately 260 Å. The particulate matter was analyzed for carbon, hydrogen and nitrogen.

This study was conducted to assess the effects of a low sulfur (<0.05 wt.%) fuel and an uncatalyzed ceramic particle trap on heavy-duty diesel emissions during both steady-state operation and during periods of electrically assisted trap regeneration. A Cummins LTA10-300 engine was operated at two steady-state modes with and without the trap. The exhaust trap system included a Corning EX-54 trap with an electrically assisted regeneration system. Both regulated emissions (oxides of nitrogen - NOx, total hydrocarbons - HC, and total particulate matter - TPM) and some unregulated emissions (polynuclear aromatic hydrocarbons - PAH soluble organic fraction - SOF, sulfates, vapor phase organics, and mutagenic activity) were measured during baseline, trap, and regeneration conditions. Emissions were collected with low sulfur (0.01 wt.%) fuel and compared to emissions with a conventional sulfur (0.32 wt.%) fuel. These fuels also varied in other fuel properties.

A study was conducted to assess the effects of controlling filter face temperatures and two differently sized collection systems on diesel total particulate matter (TPM) and vapor phase hydrocarbon levels from a diesel engine. The results were used to revise sampling protocols so that variability associated with quantitation of polynuclear aromatic hydrocarbons (PAH) is minimized. Particulate soluble organic fraction (SOF) levels (%) were compared 1) for tests where the dilute exhaust filter face temperature was held constant by varying dilution ratio (DR) to account for day to day variations in inlet air temperature to the tunnel and 2) for tests in earlier studies where the DR was held constant and the filter face temperature then varied because of varying tunnel inlet air temperature. Between date variations in %SOF were reduced by about 60% due to holding filter face temperatures constant, compared to holding DR constant.

An operational scheme with fuel-lean and exhaust gas dilution in spark-ignited engines increases thermal efficiency and decreases NOx emission, while these operations inherently induce combustion instability and thus large cycle-to-cycle variation in engine. In order to stabilize combustion variations, the development of an advanced ignition system is becoming critical. To quantify the impact of spark-ignition discharge, ignitability tests were conducted in an optically accessible combustion vessel to characterize the flame kernel development of lean methane-air mixture with CO₂ simulating exhaust diluent. A shrouded fan was used to generate turbulence in the vicinity of J-gap spark plug and a Variable Output Ignition System (VOIS) capable of producing a varied set of spark discharge patterns was developed and used as an ignition source. The main feature of the VOIS is to vary the secondary current during glow discharge including naturally decaying and truncated with multiple strikes.

Active regeneration of a catalyzed particulate filter (CPF) is affected by a number of parameters specifically particulate matter loading and inlet temperature. The MTU 1-D 2-Layer CPF model [1] was used to analyze these effects on the pressure drop, oxidation and filtration characteristics of a CPF during active regeneration. In addition, modeling results for post loading experiments were analyzed to understand the difference between loading a clean filter as compared to a partially regenerated filter. Experimental data obtained with a production Cummins regenerative particulate filter for loading, active regenerations and post loading experiments were used to calibrate the MTU 1-D 2-Layer CPF model. The model predicted results are compared with the experimental data and were analyzed to understand the CPF characteristics during active regeneration at 1.1, 2.2 and 4.1 g/L particulate matter (PM) loading and CPF inlet temperatures of 525, 550 and 600°C.