Search Results

The Late Intake-Valve Closing (LIVC) Miller cycle was applied to a turbo-charged stationary gas engine for co-generation. The engine, with a power of 324 kW, was operated under stoichiometric conditions and equipped with a three-way catalyst. The LIVC Miller cycle was aimed to improve the thermal efficiency and lower the exhaust gas temperature by increasing an expansion ratio, while avoiding engine knocking by reducing an effective compression ratio. This part of the study employed an exhaust gas recirculation (EGR) to improve the thermal efficiency of the LIVC Miller cycle engine. The EGR was expected to improve the knocking limit and reduce thermal damage to the engine's exhaust train. The experiments clarified the basic characteristics of EGR and its effect on the performance of the gas engine. The LIVC Miller cycle with EGR operating at stoichiometric conditions demonstrated a high thermal efficiency of 38 % (LHV), rivaling that of existing lean burn gas engines.

The Miller cycle was applied to a turbo-charged 324 kW gas engine with three-way catalyst. Three different methods of the Miller cycle were applied, the Early Rotary-Valve Closing (ERVC), Late Intake-Valve Closing (LIVC) and a combination of the ERVC and LIVC methods. The effect of the methods on engine performance was extensively investigated. The experimental results demonstrate a promising performance of the LIVC method, which substantially improves the thermal efficiency up to 38%, compared to 34% by the conventional Otto Cycle. The LIVC method is expected to improve engine performance with inexpensive modification. The combination of the ERVC and LIVC methods appears to further improve thermal efficiency.