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Modern commercial dual fuel engines operating in gas mode has the same level of fuel efficiency as the diesel mode. The NOx emissions level is reduced ten fold and satisfies the most stringent European 1/2 TA-Luft regulation. THC emissions can be controlled by the oxidation-catalytic process. High efficiency low NOx emissions gas engine performance is achieved by the following: Same power cylinder components as the basic diesel. Retarded timing together with short heat release duration by using Micropilot/Microcup designs. Lean lambda of 2.0 to 2.2. Minimal pilot fuel, 1% or less. Centrally located ignition if practical. Low air charge temperature at high load for high BMEP. 20-30% lower lambda at part load (compared to full load) achieved by compressed air bypass, skipfire, or variable geometry turbo. This paper provides only a qualitative treatise on gas engine combustion and the effects of fuel quality and engine design on combustion. Additional research is warranted.

This paper follows an earlier one (Ref. 1) in reviewing the present technological status of Mid-Range Truck 300/400 Series diesel engines, with emphasis on new engines and concepts presented after 1994. The elements that affect the combustion process (valve train, combustion, fuel and air-charging systems) are discussed. New head designs are proposed, including some with radial valves. Part II discusses the tools used in modern engine analysis.

Part I provides a review of present designs, advanced concepts and technologies needed for the next generation of high power density diesels for midrange truck application. Part II emphasizes the use of advanced computational tools to determine the most promising design parameters for high power density diesels which are suitable for truck application. Three types of analyses are reviewed and deemed necessary for design optimization at high power density conditions, these include: I. High BMEP cycle analysis based on zero dimensional thermodynamic analysis and engine similarity rules. II. Matching of advanced turbocharging systems for high torque rise engines. III. Multi-dimensional in-cylinder computational combustion fluid dynamics (CCFD). This analytical exercise indicates that computational tools are capable of rationalizing experimental results and therefore predicting engine performance in the conceptual stage.

This paper reviews the evolution of vehicular diesel engines, with particular attention to the major components affecting the power density, fuel economy and emissions, such as the cylinder head, valve train, combustion and injection systems. The operational inter-relationship between these systems is analyzed, with examples of present engines. Recent design improvements with gasoline engines are discussed, pointing-out certain aspects applicable to diesels. The paper concludes that by combining further-advanced systems with some of the best existing technologies, the next generation of “300 and 400 Series” engines intended for mid-range truck applications in Classes 4 to 6 could become a major export item.

The feasibility of relating crankshaft free end torsional signals to the misfiring of an individual cylinder has been established in earlier torsional simulation work [1]. This paper advances two diagnostic methods for detection of the IMEP level of individual cylinders. The first method is an enhanced pattern recognition method using both the flywheel torque fluctuation as the primary signal; and the model based reciprocating inertia knowledge for gas pressure torque harmonics determination. The enhanced pattern recognition method ensures IMEP level detection for each individual cylinder. The second method i s based on a reverse simulation algorithm. The dynamic flywheel speed fluctuation is used as the input signal to reconstruct cylinder pressure diagrams for each cylinder. In both methods, a rigorous, multi-mass, lumped mass, elastic crankshaft model is used to depict the mass-elasticity damping system.

In reviewing various industrial software modules used by bearing suppliers and engine companies, we have found a fair level of agreement between them in the final results. We also discovered, however, some unresolved areas which merit further discussion. This paper will focus primarily on those unresolved areas: 1 the treatment of partial groove bearings 2 calculation of oil flow quantity and its associated temperature rise and friction 3 selection of the bearing clearance 4 the optimal location of the journal oil hole in the main bearing 5 prediction of the fatigue endurance life 6 minimum oil thickness allowable 7 the prediction of the wear pattern. Our approach in these areas will be described and then compared with that taken in other industrial softwares.

The primary input needed for engine performance, mechanical design analysis and combustion evaluation is the dynamic cylinder pressure data. The development of an engine analyzer is herein presented. The system is based on a PC, a 500,000 samples per second A to D data acquisition system, and EngineTech Series of software. Both combustion performance and mechanical analysis can be evaluated while the engine is running. Features and assumptions used in cycle analysis and combustion software are discussed, and the available functions and results are described in this paper.

In recent years, interests in crankshaft analysis are renewed due to crankshaft difficulties in nuclear standby engine generator sets and elsewhere. Difficulties are caused by either deficiency in analysis procedure or in the nature of the fast-start application, or both. The continuous upgrading of the engine rating is another factor. Several advanced torsional calculation methods were developed in the U.S. to cope with this crankshaft crisis. These new methods were needed as neither the classical Holzer-Forced Vibration method nor the conventional classification rules seem rigid enough to determine the magnitude of the safety margin. These obsolete methods are not capable of pinpointing where the failures would be. Since 1983, PEI Consultants has been working actively in developing advanced torsional computer codes to simulate more closely what is actually happening in a shaft system.

Turbo aftercooled vehicle engine is widely accepted today. Two-stage turbo intercooled and aftercooled engines up to 300–350 bmep are in initial application stages for some medium speed stationary and marine diesels. Turbo compound engine has been tested and developed; the adiabatic engine concept has recently been advanced. For these advanced diesels, exhaust heat is a major source of engine performance improvement. Rankine bottom cycle has been applied the last few years to stationary engines for further exhaust heat recovery. Due to initial cost, complexity, and reliability of additional heat recovery equipment needed, few prototypes have been installed. Engine cycle exhaust is used as bottom cycle source heat as shown in the illustration below. This simplified H-S diagram gives a birds-eye view of how a basic diesel cycle and Rankine bottom cycle are coupled. The advancement of the adiabatic concept renders interesting potential for additional exhaust heat recovery.

The authors discuss the design and development of a single cylinder research engine which was used for combustion chamber development and for providing test data for cycle analysis. Two basic criteria for the IH engine were reproducible performance and freedom from mechanical problems. Three major designs were developed to satisfy different experimental requirements, with the ultimate goal being the achievement of advanced combustion systems beyond present limits and reduction in the cost and time required for these developments.

The first part of the paper deals with the mathematical model and computer program for simulating a compression-ignition engine. The various assumptions used and the effects of these assumptions on the results are discussed. The second part of the paper evaluates results of the engine simulation program by comparisons with experimental data and with other simplified cycle calculations. The comparisons with experimental data include motoring, part load, and full load data for a speed range of 1400–3200 rpm. The simulation results show good agreement with experimental pressure-volume diagrams. The computed trends of volumetric efficiency, heat rejection, and metal part temperatures show reasonable agreement with experimental data.