Second Law of Thermodynamics-Based Optimization of Spark-Ignition Engine Operation

摘要

Sophisticated combustion engine control strategies involving First Law of Thermodynamics parameters (FLT) have been developed over the last several decades to increase fuel conversion efficiency. However, FLT quantifies the energy of a system without considering exergy losses due to high-entropy generation in processes such as combustion. The focus of this work is to minimize the power tracking error and the entropy generation of a conventional, gasoline-fueled, spark-ignition (SI) engine by applying optimal control that considers the Second Law of Thermodynamics (SLT). Two scenarios are considered: (i) optimization over a single engine cycle to track a load value and (ii) use of model predictive control to track a changing engine load profile over many engine cycles. In both scenarios, a baseline test was performed without the minimization of the availability destruction included in the optimization cost function. The first scenario suggests a significant reduction in fuel consumption and availability destruction of 13.4% and 9.4% at full load, and 14.4% and 10.8% at a partial load, respectively, when compared to the baseline results. The second scenario confirms a lower specific fuel consumption along with an improved SLT efficiency. The maximum load tracking error was approximately 3% when considering the availability destruction in the cost function.