Heavy-duty Diesel Truck Engine Research Articles

Effect analysis on pressure sensitivity performance of diesel particulate filter for heavy-duty truck diesel engine by the nonlinear soot regeneration combustion pressure model

In this paper, the nonlinear soot regeneration combustion pressure model (NSRCMP model) is established and employed for Diesel Particulate Filter (DPF) simulation study. The NSRCMP model is reliable and accurate under simulation and experimental conditions of the process of clean filter, soot loading and soot regeneration combustion. The DPF soot loading response time and pressure drop are investigated under the parameter changes of cell density, wall thickness and permeability. It is a new attempt to measure the DPF pressure sensitivity by the trend of different design parameters. Cell density and permeability affect the soot loading time dramatically and the maximum and minimum soot loading time ratio is 3. Cell density and permeability make a significant pressure drop change through the pressure sensitivity comparisons. The corresponding ratio of maximum pressure sensitivity parameter is 2.4 when the cell density is 100 cpsi. The comparison results of pressure sensitivity under different permeabilities show a fixed ratio of 1.4. The results show that cell density is the key parameter to affect the overall system pressure. The influence of wall thickness on pressure sensitivity is not sensitive to the change of configurations of DPFs.

Effects of different piston combustion chamber heights on heat transfer and energy conversion performance enhancement of a heavy-duty truck diesel engine

The heat transfer and energy conversion characteristics of 3 kinds of pistons are studied based on the heat load prediction model of diesel engine piston. Thermal energy conversion effects of pistons for heavy-duty truck engine performance are investigated which involve air-fuel ratio, intake flow, exhaust temperature and fuel consumption. The research results illustrate the whole temperatures and heat flux of piston rise with increase of piston combustion chamber height. The maximum and the minimum temperature difference are 18.34 K and 3.07 K of piston-12, piston-15 and piston-18 with the piston wall surface temperature change dramatically. Maximum heat flux (1 203 500 W/m2, 1 488 500 W/m2, 1 523 200 W/m2) and the minimum heat flux (761.37 W/m2, 990.41 W/m2, 1325.2 W/m2) of piston-12, piston-15 and piston-18 are conspicuously conspicuously different with piston wall surface heat flux significant change. Piston-18 has the characteristics of large air-fuel ratio (27.3) and intake flow (844.33 kg/h), low fuel consumption (217.3 g/kW·h) and exhaust temperature (776.8 K), which shows that it is more efficient and the heat energy conversion capability is improved remarkably. The appropriate piston chamber height can improve heat transfer and energy conversion performance.

Reliability Analysis of Heavy-Duty Truck Diesel Engine Based on After-Sales Maintenance Data

Understanding the weak points and reliability influencing factors of products is the great significance for manufacturers to improve their design and make reasonable after-sales plans. Failure data are the basis for reliability analysis. Due to the long service life and high cost of engines, it is expensive and time-consuming to obtain failure data through reliability tests. After-sales maintenance data are an important reliability data, which intuitively reflects the field reliability performance of the product. In this paper, based on the after-sales maintenance data of heavy-duty truck diesel engines, the main failure points of diesel engines are identified, and the difference in service life of diesel engines under different service backgrounds is analyzed. In addition, gray relational analysis (GRA) is used to determine the main factors affecting the field reliability of diesel engines. The influence trend of usage rate on engine field reliability is analyzed. The results show that the fuel supply system has the highest proportion of failures in all subsystems. The failures of diesel engines mainly come from electronic devices and parts working in high-pressure environments. The service background has a significant impact on the life of the engine.

Optimization of an organic Rankine cycle constrained by the application of compact heat exchangers

Recovering waste heat from the exhaust gases of heavy-duty diesel truck engines by using the organic Rankine cycle can reduce both fuel consumption and greenhouse gas emissions. The design of such systems is constrained by the space available for installation; thus, an optimization procedure is required. In this research work, a two-objective optimization, based on the maximization of power output and minimization of the total heat exchanger surface area, is implemented in the Engineering Equation Solver software package. Application of the developed procedure is illustrated in a case with an exhaust gas temperature of 394.2 °C and mass flow rate of 0.306 kg/s. Configurations both with and without a recuperator are analyzed, and four working fluids (water, ethanol, toluene, and hexamethyldisiloxane) are compared. Of these fluids, ethanol could be recommended as the best when considering the organic Rankine cycle power output and the total area/volume of heat exchangers. For a total surface area of 10 m2 in the case without the recuperator, the power output values for ethanol, water, and toluene are 17.6 kW, 17.2 kW, and 15.8 kW, respectively; with the recuperator, the power output is slightly higher, but the total area of heat exchangers is considerably larger. Again, the best working fluid is ethanol: for a total surface area of heat exchangers of 24 m2, the power output values for ethanol, toluene, and hexamethyldisiloxane are 18 kW, 17.1 kW, and 15.8 kW, respectively. The presented procedure is useful both for the conceptual design of a complete waste heat recovery unit and for the optimization of all heat exchangers.

On the possibility to decrease the fuel consumption for a heavy-duty truck Diesel engine using the Turbo-compound method: a case study

The reduction of Diesel internal combustion engines emissions is one of the major concerns of the engines manufacturers. Despite the fact that the efficiency of the gas post-treatment systems has been significantly improved, decreasing the smoke and the soot from the cylinder inside remains a main research goal. This work is proposing a theoretical study on these pollutants formation for different kinds of direct injection methods. By dividing the in-cylinder injection the heat release characteristic could be modified, leading to different temperature and pressure levels. Using exhaust gas recirculation (EGR) the reduction of the gas temperatures might also be decreased, limiting NOx formation. To evaluate the level of the cylinder gas emissions formation a two-step procedure could be followed. First, by using a numerical calculation system the heat release characteristic can be highlighted concerning a Diesel engine with stratified injection; then, using an experimental relationship applying a large data base, the amount of the gas emissions can be subsequently provided. The authors propose some combinations between injection characteristics and EGR used fractions which could generate successfully results speaking in terms of NOx, soot and smoke formation.

A detailed modeling study of radiative heat transfer in a heavy-duty diesel engine

In recent years, the importance of radiative heat transfer in combustion has been increasingly recognized. Detailed models have become available that accurately represent the complex spectral radiative properties of reacting gas mixtures and soot particles, and new methods have been developed to solve the radiative transfer equation (RTE). At the same time, the trends toward higher operating pressures and higher levels of exhaust-gas recirculation in compression-ignition engines, together with the demand for higher quantitative accuracy from in-cylinder CFD models, has led to renewed interest in radiative transfer in engines. Here an in-depth investigation of radiative heat transfer is performed for a heavy-duty diesel truck engine over a range of operating conditions. Results from 10 different combinations of turbulent combustion models, spectral radiation property models, and RTE solvers are compared to provide insight into the global influences of radiation on energy redistribution in the combustion chamber, heat losses, and engine-out pollutant emissions (NO and soot). Also, the relative importance of the individual contributions of molecular gas versus soot radiation, the spectral model, the RTE solver, and unresolved turbulent fluctuations in composition and temperature (turbulence–radiation interactions – TRI) are investigated. Local instantaneous temperatures change by as much as 100 K with consideration of radiation, but the global influences of radiation on heat losses and engine-out emissions are relatively small (in the 5–10% range). Molecular gas radiation dominates over soot radiation, consideration of spectral properties is essential for accurate predictions of reabsorption, a simple RTE solver (a first-order spherical harmonics – P1 – method) is sufficient for the conditions investigated, and TRI effects are small (less than 10%). While the global influences of radiation are relatively small, it is nevertheless desirable to explicitly account for radiation in in-cylinder CFD. To that end, a simplified CFD radiation model has been proposed, based on the findings reported here.

Optimization and application of Stirling engine for waste heat recovery from a heavy-duty truck engine

The requirements for cleaner engines and less fuel consumption force vehicle manufacturers to investigate new technologies on recovering from losses. As the main contributor to losses is the waste heat, studies are carried out to convert the waste heat to mechanical work. In this paper, an evaluation of Stirling engines is presented for waste heat recovery (WHR) from exhaust gases of a heavy-duty truck diesel engine. Maximum theoretical dimensionless shaft work for three types of Stirling engines are calculated and compared by optimizing selected parameters with a new dimensionless method. Results are used to size a WHR system that utilizes the thermal power of a commercial truck exhaust gas. Calculations done with exhaust gas temperatures measured during road tests show that, the WHR system with Beta-type Stirling engine is more effective than Alpha and Gamma types due to its higher power density. The WHR system presented provides more than 1.3% of ICE power output and about 1% reduction in fuel consumption, which offers Stirling engine as a reasonable option for WHR on heavy-duty truck engine.

Novel testing methods for screening the tribological performance of ring-liner surfaces

The piston system accounts for about the half of the frictional losses of internal combustion engines and requires special testing methods to understand and improve its function. The most common way to screen the surface performance is to rub ring/liner segments against each other in a reciprocating manner. However, short reciprocating tests have intrinsic low sliding speeds, unable to reach the mixed/hydrodynamic regimes found in the engine, especially at the mid-stroke. This paper presents a rotating test for the oil control ring, which has the largest frictional losses of all other rings. Both reciprocating and rotating tests were conducted using different in-house developed modules and fixtures. Twin land oil control rings against liners with two different finishes commonly used in heavy duty diesel truck engines were tested under similar loads and speeds as in a real engine. Engine oil 5W-30 and room temperature was used for all the tests. Sliding speed, load, friction force and electrical resistance were recorded during the tests. The results show a clear discrimination of the different liner finishes depending on the lubrication regime present.

Microstructure and fatigue fracture mechanism for a heavy-duty truck diesel engine crankshaft

The main goal of this research is the experimental and numerical study on the fatigue function and failure of the crankshaft of diesel engine of a heavy truck. To do this, a crankshaft of the diesel engine of a heavy truck that has gone under failure after traveling 955000 km, has been used. To examine the sources of this failure, several experimental studies have been carried out including chemical composition, the strength of the material, determining the hardness and the microstructure of the material. Besides, using an elastic–plastic three dimensional finite element method (FEM) model, the location of the maximum stress in the crankshaft was determined using the ‘‘complete crankshaft model’’ and ‘‘one crank model’’. Using the results of stress analysis, was a basis for the three-dimensional crack growth model and fatigue life estimation to determine the stress intensity factor and fatigue life considering the related parameters and boundary conditions method. At the final stage, using the results gotten from the given model for the fatigue crack growth, comparing it with experimental results, and examining the whole process, it was concluded that the scratches in crankpin region, was the main reason for the fatigue failure got from bending-torsional load-combination.

A novel cascade organic Rankine cycle (ORC) system for waste heat recovery of truck diesel engines

Waste heat recovery (WHR) of engines has attracted increasingly more concerns recently, as it can improve engine thermal efficiency and help truck manufacturers meet the restrictions of CO2 emission. The organic Rankine cycle (ORC) has been considered as the most potential technology of WHR. To take full advantage of waste heat energy, the waste heat in both exhaust gases and the coolant need to be recovered; however, conventional multi-source ORC systems are too complex for vehicle applications. This paper proposed a confluent cascade expansion ORC (CCE-ORC) system for engine waste heat recovery, which has simpler architecture, a smaller volume and higher efficiency compared with conventional dual-loop ORC systems. Cyclopentane is analyzed to be regarded as the most suitable working fluid for this novel system. A thermodynamic simulation method is established for this system, and off-design performance of main components and the working fluid side pressure drop in the condenser have been taken into consideration. System performance simulations under full engine operating conditions are conducted for the application of this system on a heavy-duty truck diesel engine. Results show that the engine peak thermal efficiency can be improved from 45.3% to 49.5% where the brake specific fuel consumption (BSFC) decreases from 185.6g/(kWh) to 169.9g/(kWh). The average BSFC in the frequently operating region can decrease by 9.2% from 187.9g/(kWh) to 172.2g/(kWh). Compared with the conventional dual-loop ORC system, the CCE-ORC system can generate 8% more net power, while the total volume of heat exchangers is 18% less.

Effects of exhaust gas recycle loop layout and retarded intake valve closing on variations in combustion in a heavy-duty diesel engine

To improve engine response and decrease exhaust smoke and NOx emission during transient operations, variations in cycle-to-cycle and cylinder-to-cylinder combustion were investigated in a two-stage turbocharged, exhaust gas recirculation heavy-duty diesel truck engine. Variations in combustion were confirmed to be caused by insufficient mixing of the exhaust gas recirculation with intake air. And steady operation, by increasing the length of the mixing path, coefficient of variation of the exhaust gas recirculation rate in cylinder 1 declined from 8.12% to 3.68%, while that for the other cylinders decreased from approximately 4.0% to 2.98%. These improvements also caused reductions in coefficient of variations for indicated mean effective pressure and crank angle of 50% fuel burned (CA50). By using an intake valve closing timing retarding actuator system, coefficient of variation of the exhaust gas recirculation rate for cylinder 1 was further decreased from 3.68% to 2.82%. It was interesting to find that EGR/air mixing length revealed a great effect on soot and NOx emissions during transient operations, especially those involving sudden increases in load. By using long mixing path instead of short mixing path combined with suitable fuel injection strategy and exhaust gas recirculation rate, transient response of load was reduced by 10% and transient smoke spike decreased from 0.8m-1 to 0.5m-1.

Conversion of a heavy duty truck diesel engine with an innovative power turbine connected to the crankshaft through a continuously variable transmission to operate compression ignition dual fuel diesel-LPG

This paper considers the option to convert the diesel engine to LPG retaining the diesel-like behaviour. LPG is an alternative fuel with a better carbon to hydrogen ratio permitting reduced carbon dioxide emissions. It flashes immediately to gaseous form even if injected in liquid state for a much cleaner combustion almost cancelling some of the emissions of the diesel. Within Australia, LPG permits a much better energy security and the refueling network is widespread. In this paper, a latest heavy duty truck diesel engine with a novel power turbine connected through a continuously variable transmission to the crank shaft and fitted with a by-pass is modified to accommodate a second direct injector for the LPG fuel and operate full load with 5% diesel and 95% LPG. Results of engine performance simulations with diesel and diesel-LPG are presented. The engine retains the diesel performances while permitting the advantages of LPG in terms of particulate, carbon dioxide emissions and diversification of fuel supplies and energy security.

Thermodynamic analysis of a Rankine cycle applied on a diesel truck engine using steam and organic medium

A theoretical study is conducted to investigate the potential improvement of the overall efficiency of a heavy-duty truck diesel engine equipped with a Rankine bottoming cycle for recovering heat from the exhaust gas. To this scope, a newly developed thermodynamic simulation model has been used, considering two different working media: water and the refrigerant R245ca. As revealed from the analysis, due to the variation of exhaust gas temperature with engine load it is necessary to modify the Rankine cycle parameters i.e. high pressure and superheated vapor temperature. For this reason, a new calculation procedure is applied for the estimation of the optimum Rankine cycle parameters at each operating condition. The calculation algorithm is conducted by taking certain design criteria into account, such as the exhaust gas heat exchanger size and its pinch point requirement. From the comparative evaluation between the two working media examined, using the optimum configuration of the cycle for each operating condition, it has been revealed that the brake specific fuel consumption improvement ranges from 10.2% (at 25% engine load) to 8.5% (at 100% engine load) for R245ca and 6.1% (at 25% engine load) to 7.5% (at 100% engine load) for water.

Diesel-like and HCCI-like operation of a truck engine converted to hydrogen

In addition to the traditional spark ignition (SI), premixed, gasoline-like and compression ignition (CI), diffusion, Diesel-like operation of internal combustion engines, premixed, homogeneous charge, compression ignition (HCCI) operation has also been proposed to improve the fuel conversion efficiency and reduce the pollutant formation. To be attractive, the operation in HCCI mode has to be coupled with the other traditional operations, being HCCI in general difficult to be controlled and limited to values of the air-to-fuel equivalence ratio λ within a narrow windows set by the lean burn limits with large λ and the peak pressure limits with small λ. Furthermore, the specific kinetics of hydrogen makes this fuel more difficult than other hydrocarbons to work in an engine operating HCCI without assistance. In a recent paper, the design of a 12.8 L in-line six cylinder turbo charged directly injected heavy duty truck Diesel engine fuelled with hydrogen has been discussed. Conversion of a latest Diesel engine with a novel power turbine has been studied replacing the in-cylinder Diesel injector and glow plug with a hydrogen injector and a jet ignition pre-chamber. The pre-chamber is a small volume accommodating another hydrogen injector and a glow plug being connected to the in-cylinder through calibrated orifices. This design permits to operate the engine in four different modes: – diffusion with jet ignition M 1 - an injection occurs in the jet ignition pre-chamber before the main chamber fuel is injected and the engine operates therefore Diesel-like; – mixed diffusion/premixed Diesel/gasoline like M 2 - an injection occurs in the jet ignition pre-chamber after only part of the main chamber fuel is injected and mixed with air; – premixed with jet ignition M 3 - an injection occurs in the jet ignition pre-chamber after the main chamber fuel is injected and mixed with air and the engine operates gasoline-like; – premixed without jet ignition M 4 - no injection occurs in the jet ignition pre-chamber and the engine operates HCCI-like. While only the Diesel-like operation was previously considered full load, all the modes including the operation HCCI-like are considered here over the full range of loads where the power turbine is either connected to the crankshaft or disconnected and the exhaust gases pass through this turbine or bypass the turbine. This paper deals with computational rather than experimental work. Computations are made with the latest predictive HCCI model using detailed kinetics of GT-POWER and the well established correlative Wiebe models for Diesel and gasoline combustion. HCCI-like operation is considered over a range of air-to-fuel equivalence ratio λ much wider than usually considered with other fuels being perhaps even more suitable than hydrogen to this operation thanks to the jet ignition assistance.

Advances in hydrogen compression ignition internal combustion engines

The turbocharged direct injection lean burn Diesel engine is the most efficient engine now in production for transport applications within heavy duty trucks applications full load brake engine thermal efficiencies up to 45% and reduced penalties in brake engine thermal efficiencies reducing the load by the quantity of fuel injected. The secrets of this engine’s performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. The major downfalls of this engine are the carbon dioxide emissions and the depletion of natural resources using fossil Diesel, the energy security issues of using foreign fuels in general, and finally the difficulty to meet future emission standards, for the intrinsically “dirty” combustion of the fuel made up of a mixture of many hydrocarbon being injected in liquid state and the lack of maturity for the lean burn after treatment system. Renewable hydrogen is a possible replacement for the future of the Diesel that is free of carbon dioxide and other major emissions with the only exception of nitric dioxides, and it therefore makes sense to discuss the option to convert not only passenger car engines, but also heavy duty truck engines to run hydrogen. In this paper, a heavy duty Diesel truck engine is modelled and converted to run hydrogen only with goals retaining the same of Diesel full and part load efficiencies and power and torque outputs. The modelled hydrogen engine has actually better than Diesel fuel efficiencies all over the load range and it also permits better full load power and torque outputs running about same stoichiometry. Hydrogen has been considered so far mainly as a fuel alternative to gasoline in passenger car applications operating with spark ignition, with just a couple of examples of use of hydrogen as a fuel alternative to Diesel in passenger car applications operating compression ignition. The novelty of the manuscript is the heavy duty truck (HDT) application of hydrogen in a converted Diesel engine retaining the compression ignition operation of the Diesel. This application requires the design of a novel combustion system made up of a jet ignition pre-chamber with a glow plug and a fuel injector and a main chamber direct fuel injector. The pre-chamber injection of hydrogen permits combustion to start assisted by a glow plug and then to move to the main chamber. At this stage, the hydrogen already injected in the main chamber and mixed with the air will burn premixed gasoline-like, while the remaining hydrogen to be injected in the main chamber will then burn diffusion Diesel-like. This innovative combustion mode is the core of the technical note.

Comparison of exhaust emissions and their mutagenicity from the combustion of biodiesel, vegetable oil, gas-to-liquid and petrodiesel fuels

Efforts are under way to reduce diesel engine emissions (DEE) and their content of carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAH). Previously, we observed reduced PAH emissions and DEE mutagenicity caused by reformulated or newly developed fuels. The use of rapeseed oil as diesel engine fuel is growing in German transportation businesses and agriculture. We now compared the mutagenic effects of DEE from rapeseed oil (RSO), rapeseed methyl ester (RME, biodiesel), natural gas-derived synthetic fuel (gas-to-liquid, GTL), and a reference petrodiesel fuel (DF) generated by a heavy-duty truck diesel engine using the European Stationary Cycle. Mutagenicity of the particle extracts and the condensates was tested using the Salmonella typhimurium mammalian microsome assay with strains TA98 and TA100. The RSO particle extracts increased the mutagenic effects by factors of 9.7 up to 17 in strain TA98 and of 5.4 up to 6.4 in strain TA100 compared with the reference DF. The RSO condensates caused up to three times stronger mutagenicity than the reference fuel. RME extracts had a moderate but significantly higher mutagenic response in assays of TA98 with metabolic activation and TA100 without metabolic activation. GTL samples did not differ significantly from DF. Regulated emissions (hydrocarbons, carbon monoxide, nitrogen oxides (NO x ), and particulate matter) remained below the limits except for an increase in NO x exhaust emissions of up to 15% from the tested biofuels.

On-road and laboratory evaluation of combustion aerosols—Part1: Summary of diesel engine results

The objective was to characterize diesel exhaust aerosols on road and to duplicate the results in the laboratory without altering the physical characteristics of the nuclei mode. On-road emissions from four, heavy-duty diesel truck engines were measured. The same engines were reevaluated in the manufacturers’ laboratories. For highway cruise and acceleration conditions, all engines produced bimodal size distributions with the nuclei mode ranging in size from 6 to 11 nm and the accumulation mode from 52 to 62 nm. On-road size distribution measurements nearly always showed a nuclei mode while laboratory measurements showed a nuclei mode under many, but not all conditions. Laboratory studies showed that nuclei mode particles consisted mainly of heavy hydrocarbons. More than 97% of the volume of 12 and 30 nm particles disappeared on heating to 400 °C. The volatility resembled that of C24–C32 n-alkanes implying a significant contribution from lubricating oil.

Effects of Engine Speed and Accessory Load on Idling Emissions from Heavy-Duty Diesel Truck Engines

A nontrivial portion of heavy-duty vehicle emissions of NOx and particulate matter (PM) occurs during idling. Regulators and the environmental community are interested in curtailing truck idling emissions, but current emissions models do not characterize them accurately, and little quantitative data exist to evaluate the relative effectiveness of various policies. The objectives of this study were to quantify the effect of accessory loading and engine speed on idling emissions from a properly functioning, modern, heavy-duty diesel truck and to compare these results with data from earlier model year vehicles. It was found that emissions during idling varied greatly as a function of engine model year, engine speed, and accessory load conditions. For the 1999 model year Class 8 truck tested, raising the engine speed from 600 to 1050 rpm and turning on the air conditioning resulted in a 2.5-fold increase in NOx emissions in grams per hour, a 2-fold increase in CO2 emissions, and a 5-fold increase in CO emissions while idling. On a grams per gallon fuel basis, NOx emissions while idling were approximately twice as high as those at 55 mph. The CO2 emissions at the two conditions were closer. The NOx emissions from the 1999 truck while idling with air conditioning running were slightly more than those of two 1990 model year trucks under equivalent conditions, and the hydrocarbon (HC) and CO emissions were significantly lower. It was found that the NOx emissions used in the California Air Resources Board’s (CARB) EMFAC2000 and the U.S. Environmental Protection Agency’s (EPA) MOBILE5b emissions inventory models were lower than those measured in all of the idling conditions tested on the 1999 truck.

Optimisation of a dosing strategy for an HC-SCR diesel exhaust after-treatment system

Several principal aspects and components of an advanced catalytic exhaust after-treatment system for NO x reduction on a heavy-duty diesel truck engine have been systematically examined and evaluated. The after-treatment system consists of de-NO x catalysts, injection of a reducing agent (diesel fuel), and computer programs to model the engine and catalysts in real time. These models are combined with a third program, a strategy, to control the injection of reducing agent during transient operation. Evaluation of the system was performed using the standard European transient cycle (ETC). The benefits and disadvantages of an oxidation catalyst upstream the reductant injection are clarified. Whereas an increased NO 2/NO ratio is beneficial at larger reductant dosages, the effects of temperature levelling and delay are detrimental for system performance. The dynamic effect of introducing a strategy for distributing the reducing agent in time is elucidated. The strategy itself is presented and the process of its systematic optimisation is closely followed. Implications of the optimisation are that catalyst temperature is the most important variable in the strategy. Also, a considerable part of the reducing agent should be distributed at low and intermediate temperatures, for utilising an increased NO 2/NO ratio. Furthermore, results suggest that a smooth, rather than instantaneous, adjustment of reductant dosage to driving conditions is necessary. Finally, a set-up with two injectors is examined for its potential in the application. It is shown to be of disadvantage for the ETC as a whole, but may not be so at lower exhaust gas flows.

A methodology for engine design using multi-dimensional modelling and genetic algorithms with validation through experiments

A methodology for internal combustion engine design has been formulated which incorporates multidimensional modelling and experiments to optimize and simulate direct injection diesel engine combustion and emissions formation. The computer code KIVA-GA performs full-cycle engine simulations within the framework of a genetic algorithm (GA) global optimization code. The methodology is applied to optimize a heavy-duty diesel truck engine. The study simultaneously investigated the effects of six engine input parameters on emissions and performance for a high-speed medium-load operating point. The start of injection (SOI), injection pressure, amount of exhaust gas recirculation (EGR), boost pressure and split injection rate shape were optimized. The convergence of the GA optimization process is demonstrated and the results were compared to those of the experimental optimization study employing a response surface method (RSM), which uses statistically designed experiments to determine an optimum design. In addition, the parameters of the computationally predicted optimum were run experimentally and good agreement was obtained. The potential for ultra-low emissions levels was assessed through additional computational GA runs that included higher maximum EGR levels (up to 50 per cent). The predicted optimum results in significantly lower soot and NOx emissions together with improved fuel consumption compared to the baseline design. The present results indicate that an efficient design methodology has been developed for optimization of internal combustion engines, one that allows simultaneous optimization of a large number of parameters.