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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].

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.

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.

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.

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.

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.

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.

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.

To meet future NO, heavy-duty diesel emissions standards, exhaust gas recirculation (EGR) technology is likely to be used. To improve fuel economy and further lower emissions, the recirculated exhaust gas needs to be cooled, with the possibility that cooling of the exhaust gas may form sulfuric acid condensate in the EGR cooler. This corrosive condensate can cause EGR cooler failure and consequentially result in severe damage to the engine. Both a literature review and a preliminary experimental study were conducted. In this study, a manually controlled EGR system was installed on a 1995 Cummins Ml l-330E engine which was operated at EPA mode 9* (1800 rpm and 75% load). The Goksoyr-Ross method (1)** was used to measure the particle-phase sulfate and vapor-phase H2SO4 and SO2 at the inlet and outlet locations of the EGR cooler, obtaining H2SO4 and SO2 concentrations. About 0.5% of fuel sulfur in the EGR cooler was in the particle-phase.

A 2-D computational model was developed to describe the flow and filtration processes, in a honeycomb structured ceramic diesel particulate trap. This model describes the steady state trap loading, as well as the transient behavior of the flow and filtration processes. The theoretical model includes the effect of a copper fuel additive on trap loading and transient operation. The convective terms were based on a 2-D analytical flow field solution derived from the conservation of mass and momentum equations. The filtration theory incorporated in the time dependent numerical code included the diffusion, inertia, and direct interception mechanisms. Based on a measured upstream particle size distribution, using the filtration theory, the downstream particle size distribution was calculated. The theoretical filtration efficiency, based on particle size distribution, agreed very well (within 1%) with experimental data for a number of different cases.

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.

The goals of this research are to understand the regeneration process in ceramic (Cordierite) monolith traps using a copper fuel additive and to investigate the various conditions that lead to trap regeneration failure. The copper additive lowers the trap regeneration temperature from approximately 500 °C to 375 °C and decreases the time necessary for regeneration. Because of these characteristics, it is important to understand the effect of the additive on regeneration when excessive particulate matter accumulation occurs in the trap. The effects of particulate mass loading on regeneration temperatures and regeneration time were studied for both the controlled (engine operated at full load rated speed) and uncontrolled (trap regeneration initiated at full load rated speed after which the engine was cut to idle) conditions. The trap peak temperatures were higher for the uncontrolled than the controlled regeneration.

This research quantifies the effects of a copper fuel additive on the regulated [oxides of nitrogen (NOx), hydrocarbons (HC) and total particulate matter (TPM)] and unregulated emissions [soluble organic fraction (SOF), vapor phase organics (XOC), polynuclear aromatic hydrocarbons (PAH), nitro-PAH, particle size distributions and mutagenic activity] from a 1988 Cummins LTA10 diesel engine using a low sulfur fuel. The engine was operated at two steady state modes (EPA modes 9 and 11, which are 75 and 25% load at rated speed, respectively) and five additive levels (0, 15, 30, 60 and 100 ppm Cu by mass) with and without a ceramic trap. Measurements of PAH and mutagenic activity were limited to the 0, 30 and 60 ppm Cu levels. Data were also collected to assess the effect of the additive on regeneration temperature and duration. Copper species collected within the trap were identified and exhaust copper concentrations quantified.

An analysis of vehicle engine cooling airflow by means of a one-dimensional, transient, compressible flow model was carried out and revealed that similarity theory could be applied to investigate the variation of the airflow with ambient and operating conditions. It was recognized that for a given vehicle engine cooling system, the cooling airflow behavior could be explained using several dimensionless parameters that involve the vehicle speed, fan speed, heat transfer rate through the radiator, ambient temperature and pressure, and the system characteristic dimension. Using the flow resistance and fan characteristics measured from a prototype cooling system and the computer simulation for the one-dimensional compressible flow model, a quantitative correlation of non-dimensional mass flow rate to three dimensionless parameters for a prototype heavy-duty truck was established. The results are presented in charts, tables, and formulas.

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.

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.

The effect of the use of a manganese-copper fuel additive with a Corning EX-47 particulate trap on heavy-duty diesel emissions has been investigated; reductions in total particulate matter (70%), sulfates (65%), and the soluble organic fraction (SOF) (62%) were measured in the diluted (15:1) exhaust and solids were reduced by 94% as measured in the raw exhaust. The use of the additive plus the trap had the same effect on gaseous emissions (hydrocarbons and oxides of nitrogen) as did the trap alone. The use of the additive without the trap had no effect on measured gaseous emissions, although sulfate increased by 20%. Approximately 50% of the metals added to the fuel were calculated to be retained in the engine system. The metals emitted by the engine were collected very efficiently (>97%) by the trap even during regeneration, which occured 180°C lower when the additive was used.

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.

The Vehicle Engine Cooling System Simulation (VECSS) developed at Michigan Technological University in 1982 was enhanced to the extent that it can be used as a cooling system design tool for a heavy duty diesel truck. The enhancements are described in the present paper, while the use of the VECSS as a cooling system design tool is presented in the companion paper, “The Use of the Vehicle Engine Cooling System Simulation as a Cooling System Design Tool.” The enhanced VECSS was validated by comparing predicted temperature results to data collected by the Cummin's Engine Company during Air-to-Boil (ATB) tests, and during an “over-the-road” dynamic run of a heavy duty diesel truck. The enhanced model provided results which compared very favorably to both, the steady state ATB data and the dynamic “over-the-road” data.

A computer simulation model to predict the thermal responses of an on-highway heavy duty diesel truck in transient operation was used to study several important cooling system design and operating variables. The truck used in this study was an International Harvester COF-9670 cab-over-chassis vehicle equipped with a McCord radiator, Cummins NTC-350 diesel engine, Kysor fan-clutch and shutter system, aftercooler, and standard cab heater and cooling system components. 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 computer simulation model. The thermostat-fan, thermostat-shutter-fan, and thermostat-winterfront-fan systems were studied.