Dynamic Modeling of a Homogeneous Charge Compression Ignition Engine with Exhaust Throttle

Abstract

<div class="section abstract"><div class="htmlview paragraph">Homogeneous charge compression ignition (HCCI) engines create a more efficient power source for either stationary power generators or automotive applications. Control of HCCI engines, however, is difficult since the ignition cannot be actuated directly. For the purpose of model-based analysis and control design, a crank-angle based HCCI engine model is developed in this paper based on experimental data from a single-cylinder engine. The zero-dimensional dynamic engine model is constructed based on conservation of mass and energy, and ideal gas law. Subsystems in this model included valve lift profile, cylinder volume, mass flow rate, intake and exhaust runner dynamics, cylinder dynamics, combustion model and heat-transfer model. Inputs to the model include engine speed, intake temperature, fueling rate, intake throttle and exhaust throttle positions. Outputs of the model include indicate mean effective pressure (IMEP), combustion timings, air-to-fuel ratio (AFR), and the pressure, temperature, mass and burned gas fraction in the cylinder, intake and exhaust runners. Identification and validation of the combustion model were first conducted based on the steady-state cylinder pressure measurement and the combustion analysis results. With the inclusion of intake and exhaust runner dynamics and cylinder filling dynamics, the complete HCCI engine model is then validated against steady-state experimental data at various intake temperatures and transient experimental data during step changes of fueling rate exhaust throttle position. Simulation results also contain details such as mass flow rate through the intake and exhaust valves and cylinder charge conditions during the transient. In the future, this model can be used for control design and hardware in the loop (HIL) simulation and testing.</div></div>