Second-Law Analysis of Boosted HCCI Engines: Modeling Study

Abstract

Homogeneous charge compression ignition (HCCI) combustion has shown the potential to improve gasoline engine efficiency, by integration into future dual-mode spark ignition/HCCI engines. With the current trend of downsizing and boosting, it is critical to implement HCCI combustion under elevated pressure, and assess its potential for high load and efficient operation. Thermodynamic analysis of such engines provides insight into the energy flows of the systems, and enables optimal design for efficiency. This study is focused on modeling a 4-cylinder boosted HCCI engine, and utilizing second law to describe the exergy flows of the system in order to identify areas of irreversibilities and inefficiencies. The implications of boosting and variable valve actuation on exergy flows are discussed and analyzed. Results from this modeling study indicated that light-duty boosted HCCI can be utilized up to 10-bar brake mean effective pressure (BMEP) with peak brake efficiency of 39%.