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A heat release analysis of experimental pressure diagrams, appropriate for indirect injection (divided chamber) diesel engines, is developed and used to obtain heat release rate profiles during the combustion process in each combustion chamber. Attention is paid to the correct processing of the data, due to the inherent complexity of the mass interchange between the two combustion chambers. The analysis concerns a turbocharged, indirect injection diesel engine, having a very small pre-chamber and a very narrow connecting passageway, operated at various load and speed conditions, located at the authors' laboratory. An extended experimental work, at steady-state conditions, is conducted on a specially developed test bed configuration of this engine, which is connected to a high-speed data acquisition and processing system.

A second-law analysis is performed in both chambers of an indirect injection turbocharged diesel engine and the simulation program developed is used to study the second-law performance of the engine at various operating conditions, steady state and transient. The simulation developed is based on the filling and emptying approach and provides detailed analysis of thermodynamic, dynamic and second-law differential equations on a degree crank angle basis. It incorporates a detailed mathematical simulation of the fuel pump and solves each equation separately for each one of the six cylinders of the engine in hand. The model is validated against experimental data at steady state and transient conditions, obtained at the authors' laboratory. The prechamber rate and cumulative availability terms and irreversibilities are computed and depicted against the main chamber ones during the 720 degrees crank angle of an engine cycle.

The transient operation of turbocharged diesel engines during turbocharger compressor surging is investigated through simulation. This form of compressor dynamic instability can generate large amplitude compressor mass flow and pressure rise oscillations, sometimes leading even to flow reversals, and may also induce severe torsional loading to the turbocharger shaft. A model predicting the dynamic behavior of the engine air-charging system when compressor surging occurs was developed in conjunction with a linearized quasi-steady diesel engine simulation code. This analysis possesses the advantage over the more detailed engine codes of basic simplicity, speed of calculation and no need of many engine and turbocharger components parameters given as input data. Emphasis is given to the correct modeling of the physics of the phenomena concerned. Transient operation runs, including critical cases for surging initiation, were applied for two similar six-cylinder diesel engines.