Search Results

A model for calculating the trap pressure drop, various particulate properties, filtration characteristics and trap temperatures was developed during the steady-state and transient cycles using the theory originated by Opris and Johnson, 1998. This model was validated with the data obtained from the steady-state cycles run with an IBIDEN SiC diesel particulate filter. To evaluate the trap experimental filtration efficiency, raw exhaust samples were taken upstream and downstream of the trap. A trap scaling and equivalent comparison model was developed for comparing different traps at the same volume and same filtration area. Using the model, the trap pressure drop data obtained from different traps were compared equivalently at the same trap volume and same filtration area. The pressure drop performance of the IBIDEN SiC trap compared favorably to the previously tested NoTox SiC and the Cordierite traps.

A Vehicle-Engine-Cooling (VEC) system computer simulation model was used to study the transient performance of control devices and their temperature settings on oil, coolant and cab temperatures. The truck used in the study was an International Harvester COF-9670 cab over chassis heavy-duty vehicle equipped with a standard cab heater, a Cummins NTC-350 diesel engine with a McCord radiator and standard cooling system components and aftercooler. Input data from several portions of a Columbus to Bloomington, Indiana route were used from the Vehicle Mission Simulation (VMS) program to determine engine and vehicle operating conditions for the VEC system computer simulation model. The control devices investigated were the standard thermostat, the Kysor fan-clutch and shutter system. The effect of shutterstat location on shutter performance along with thermostat, shutter and fan activation temperature settings were investigated for ambient temperatures of 32, 85 and 100°F.

A computer simulation of the turbocharged direct- injection diesel engine was developed to enhance the capabilities of the Vehicle Engine Cooling System Simulation (VECSS) developed at Michigan Technological University. The engine model was extensively validated against Detroit Diesel Corporation's (DDC) Series 60 engine data. In addition to the new engine model a charge-air-cooler model was developed and incorporated into the VECSS. A Freightliner truck with a Detroit Diesel's Series 60 engine, Behr McCord radiator, AlliedSignal/Garrett Automotive charge air cooler, Kysor DST variable speed fan clutch and other cooling system components was used for the study. The data were collected using the Detroit Diesel Electronic Controls (DDEC)-Electronic Control Module (ECM) and Hewlett Packard data acquisition system. The enhanced model's results were compared to the steady state TTD (top tank differential) data.

In order to comply with 2002 EPA emissions regulations, cooled exhaust gas recirculation (EGR) will be used by heavy duty (HD) diesel engine manufacturers as the primary means to reduce emissions of nitrogen oxides (NOx). A feedforward controlled EGR cooling system with a secondary electric water pump and proportional-integral-derivative (PID) feedback has been designed to cool the recirculated exhaust gas in order to better realize the benefits of EGR without overcooling the exhaust gas since overcooling leads to the fouling of the EGR cooler with acidic residues. A system without a variable controlled coolant flow rate is not able to achieve these goals because the exhaust temperature and the EGR schedule vary significantly, especially under transient and warm-up operating conditions. Simulation results presented in this paper have been determined using the Vehicle Engine Cooling System Simulation (VECSS) software, which has been developed and validated using actual engine data.

Monitoring of the wear rate of a diesel engine will yield valuable information regarding the wear mechanism within a diesel engine and ultimately will improve the predictions of failing engines and/or their components to allow preventive maintenance which will prolong the life of the engine. A mathematical model was developed that describes the wear particle concentration as a function of time in a diesel engine. This model contains engine and lubrication system parameters that determine the concentration of wear particles in the engine sump. These variables are the oil system volume, oil flow rate, particle generation rate, filtering efficiency and the initial particle concentration. The model has been employed to study the wear particle concentrations in the sump and the mass of particles in the filter for the Cummins VT-903 diesel engine.

Engineers have found that the one-dimensional approach to compressible flows in ducts is extremely informative and effective. This paper extends these methods to cooling airflow for engine cooling system that they may be used to understand and estimate the behavior of cooling air flow in a complex duct system.

Because of the more hostile environment in the compression ignition engine compared to the spark ignition engine, development and application of CI engine in-cylinder diagnostic methods have lagged those for SI engines. However, with more stringent federally mandated particulate and NOx standards which will go into effect in 1991 and 1994, the need for detailed information on the combustion processes in the cylinder is vital to controlling tailpipe emissions. The present paper contains a summary of the state-of-the-art techniques for determining in-situ species concentrations and profiles; particle concentrations, profiles, and size distributions; and temperature fields. Optical and physical probing methods, total cylinder dumping methods, and optical diagnostics applied for use in CI engine combustion chambers are discussed.

A set of control functions have been investigated for a computer controlled diesel cooling system, using the vehicle engine cooling system code. Various engine operating conditions such as the engine load, engine speed, and ambient temperature are considered as the controlling variables in the control loops. The truck simulated in the study was an International Harvester COF-9670 cab over chassis heavy-duty vehicle equipped with a standard cab heater, a Cummins NTC-350 diesel engine with a McCord radiator and standard cooling system components and after-cooler. The vehicle also had a Kysor fan-clutch and shutter system. Comparison simulation tests between the conventional cooling system and the computer controlled cooling system using the Vehicle-Engine-Cooling Computer System model under different ambient and route conditions show that the computer controlled cooling system would offer the following benefits: 1.

Experimental Brake Specific Fuel Consumption (BSFC) data are presented for two engines as a function of engine speed, load, outlet coolant temperature and inlet oil temperature. The engines used in the study were the Cummins VT-903 (turbocharged) and the Caterpillar 3208, both being direct-injection and four-cycle. The data were taken for the Cat 3208 engine using a fractional factorial statistical method which reduced the total test matrix from 256 to 64 data points. The experimental data are used in the development of BSFC regression equations as a function of load, speed, outlet coolant temperature and inlet oil temperatures. A mathematical parameter for expressing quantitatively the change of BSFC per 10°F change in coolant and oil temperature is presented. It was found that an increase in the coolant and/or oil temperatures had the effect of reducing BSFC in both engines.

Diesel engine fuel consumption is mainly a function of engine component design and power requirements. However, fuel consumption can also be affected by the environment in which the engine operates. This paper considers two controlling parameters of the engine's thermal environment, oil temperature and coolant temperature. The effects of oil and coolant temperatures on Brake Specific Fuel Consumption (BSFC) are established for a turbocharged diesel engine. Data are also presented for a direct injection, naturally aspirated diesel engine. A matrix of test conditions was run on a Cummins VT-903 diesel engine to evaluate the effects of oil and coolant temperatures on BSFC for several loads and speeds. Loads and speeds were selected based on where a typical semi-tractor engine would operate over the road on a hills and curves route. Oil temperature was monitored and controlled between the oil cooler and the engine. Coolant temperature was monitored and controlled at the engine outlet.

Active regeneration experiments were performed on a Cummins 2007 aftertreatment system by hydrocarbon dosing with injection of diesel fuel downstream of the turbocharger. The main objective was to characterize the thermal oxidation rate as a function of temperature and particulate matter (PM) loading of the catalyzed particulate filter (CPF). Partial regeneration tests were carried out to ensure measureable masses are retained in the CPF in order to model the oxidation kinetics. The CPF was subsequently re-loaded to determine the effects of partial regeneration during post-loading. A methodology for gathering particulate data for analysis and determination of thermal oxidation in a CPF system operating in the engine exhaust was developed. Durations of the active regeneration experiments were estimated using previous active regeneration work by Singh et al. 2006 [1] and were adjusted as the experiments progressed using a lumped oxidation model [2, 3].

Combustion characteristics of an L-head engine combustion chamber have been examined using ionization probes and piezioelectric pressure transducers. The method describes how pressure rise rates, peak pressures, mean effective pressures, and flame arrival times were recorded. The flame arrival times were then used to find the position and shape of the flame front as a function of time. The influence of spark plug location on the above parameters was then examined for two different combustion chamber shapes.

A thermal management system for heavy duty diesel engines is presented for maintaining acceptable and constant engine temperatures over a wide range of operational conditions. It consists of a computer controlled variable speed coolant pump, a position controlled thermostat, and a model-based control strategy. An experimentally validated, diesel engine cooling system simulation was used to demonstrate the thermal management system's capability to reduce power consumption. The controller was evaluated using a variety of operating scenarios across a wide range of loads, vehicle speeds, and ambient temperatures. Three metrics were used to assess the effects of the computer controlled system: engine temperature, energy savings, and cab temperature. The proposed control system provided very good control over the engine coolant temperatures while maintaining engine metal temperatures within a desired range.

A computer simulation program was developed to simulate the thermal responses of an on-highway, heavy duty diesel powered truck in transient operation for evaluation of cooling system performance. Mathematical models of the engine, heat exchangers, lubricating oil system, thermal control sensors (thermostat and shutterstat), auxiliary components, and the cab were formulated and calibrated to laboratory experimental data. The component models were assembled into the vehicle engine cooling system model and used to predict air-to-boil temperatures. The model has the capability to predict real time coolant, oil and cab temperatures using vehicle simulation input data over various routes.

The increasing complexity of vehicle engine cooling systems results in additional system interactions. Design and evaluation of such systems and related interactions requires a fully coupled detailed engine and cooling system model. The Vehicle Engine Cooling System Simulation (VECSS) developed at Michigan Technological University was enhanced by linking with GT-POWER for the engine/cycle analysis model. Enhanced VECSS (E-VECSS) predicts the effects of cooling system performance on engine performance including accessory power and fuel conversion efficiency. Along with the engine cycle, modeled components include the engine manifolds, turbocharger, radiator, charge-air-cooler, engine oil circuit, oil cooler, cab heater, coolant pump, thermostat, and fan. This tool was then applied to develop and simulate an actively controlled electric cooling system for a 12.7 liter diesel engine.

An adaptive control system which determines the optimum system parameters based on the engine response to changes in those parameters, has been tested as an ignition timing control system on several gaseous fueled engines. The changes in the MBT timing for speed, load, air-fuel ratio, and fuel type were explored. The ability of the control system to correct the timing for these parameters was demonstrated. An air-fuel ratio control based on the same technique is also discussed.

Flame arrival data, determined by ionization gaps and a radiation detector, are presented for a multi-hole CFR engine equipped with six spark plugs spaced around the periphery of the combustion chamber, using a shrouded intake valve to produce swirl and with a standard valve to eliminate it. For results with the shrouded valve, path equations for the burnt gases are derived for several velocity distributions that satisfy the Navier-Stokes equations of motion for the unburned gas. Previous velocity distribution and observed flame movement data are presented in support of the derived model for the path of the burnt gases.

Low emission heavy-duty diesel engines are increasingly utilizing four-valve designs with vertical central injectors. However, two-valve DI diesel engines with inclined injectors offset from the centerline of the piston bowl are likely to continue to be used in medium and light duty applications for some time. In such situations, designing of the hole-type nozzle is very difficult and may cause unavoidable back-drilling problems. The purpose of this paper is to solve back-drilling problems connected with hole-type nozzles and improve fuel-air mixing which leads to more efficient combustion. Based on geometric considerations, this paper introduces single-cone hole-type nozzles, double-cone hole-type nozzles, and the critical principal angles for hole-type nozzles. The single-cone hole-type nozzles and double-cone hole-type nozzles can meet requirements for height of the spray impingement points and spray orifice distribution angle at the same time.

Measurements of particle concentrations in one cylinder of a 1982 5.7 liter GM V-8 diesel engine have been made using a unique total cylinder sampling system. The first part of the paper is devoted to an examination of the performance of the sampling system. The role of blowoff and nucleation in the formation of sample artifacts is discussed. The remainder of the paper is devoted to the results of a study of the formation and removal of carbon particles during diesel engine combustion. Several operating conditions have been examined. The influence of injection timing, load, EGR, and oxygen addition on particle formation and removal has been investigated. The concentrations of volatile and nonvolatile particulate matter have been measured as a function of crankangle position. Particle formation begins 1-5 crankangle degrees (CAD) after the start of combustion.

The formation of particles in the combustion chamber of a direct injection diesel engine has been studied with the use of the Total Cylinder Sampling Method. With this method, nearly the entire contents of the cylinder of an operating diesel engine can be quickly removed at various times during the combustion process. The particle mass and size distributions present in the sample can then be analyzed. If quenching of the combustion process is quick and complete, the resulting samples are representative of the particle mass and size distributions present in the cylinder near the time sampling begins. This paper discusses the effect of injection timing and piston bowl shape on the particle formation and oxidation. Example size distribution measurements are also shown. The particle concentrations in the cylinder were measured for three different injection timings with the standard piston installed in the engine.