Fast heat release characterization of a diesel engine

Abstract

Multi-event fuel injection strategies under independently controlled exhaust gas recirculation and intake boost have been applied to produce the heat release patterns that characterize the clean combustion techniques of modern diesel engines. Extensive experimental and analytical comparisons have been performed to better estimate the heat release characteristics from the cylinder pressure traces. A number of heat release models based on the First Principles are compared against a comprehensive heat release model, on the basis of numerical complexity and the ability to characterize the combustion process. Such study indicated that though the estimation from the simplified models is efficient when the heat release is close to the end of the cylinder compression stroke, the simplified models produce shortfalls in estimating the more spread multi-event heat release from the newer combustion systems. A new computationally efficient algorithm, based on the Diesel Pressure Departure Ratio, is proposed to characterize the various heat release patterns with adequate accuracy. The improved heat release analyzing algorithms are further programmed on real-time deterministic devices that process the cylinder pressure data to provide the necessary feedback for the fuel-injection model running on subsequent real-time controllers. The efficacy of the new algorithms has been experimentally demonstrated against selected cases of boost, engine load and exhaust gas recirculation on a modern diesel engine.