Ph.D. Defense | Ponnya Hlaing

Title

Influence of Internal Geometry on Pre-chamber Combustion Concept in a Lean Burn Natural Gas Engine


Ponnya Hlaing, Ph.D. Candidate supervised by Prof. James W. Turner and Prof. Hong G. Im

Date: Tuesday, August 23, 2022

Time: 1-2 PM

Location: Room 5209, Level 5, Building 5

Zoom: https://kaust.zoom.us/j/95808358399

Abstract

 

The road transport sector, dominated by internal combustion engines, accounts for as high as 23% of annual carbon emissions and is considered the major area where urgent carbon reduction strategies are required. Novel lean combustion shows promises for improved engine efficiency, thereby reducing carbon emissions for a given mass of fuel while simultaneously reducing thermal NOx emissions. Igniting lean methane-air mixtures is a challenge and requires high ignition energy, often beyond the capability of conventional spark ignition systems. The pre-chamber combustion (PCC) concept can readily provide the required ignition energy while requiring relatively simple components and adequate control over the combustion processes.

In this thesis work, the application of the pre-chamber combustion concept was demonstrated in a heavy-duty research engine. While most pre-chamber designs found in the literature are bulky and require extensive cylinder head modifications or complete engine redesign, the narrow-throat pre-chamber design was implemented, which can readily fit the diesel injector pockets of most heavy-duty engines without the need for substantial hardware modifications. The unique pre-chamber design is significantly different from the contemporary pre-chamber geometries, and its engine combustion phenomena and operating characteristics are largely unknown.

This thesis work investigates the effect of important pre-chamber dimensions, such as the volume, nozzle hole diameter, and throat diameter, on the engine operating characteristics and emission trends by employing different pre-chambers. The experiments focus on the lean operation with excess air ratio (λ) exceeding 1.6. From the literature survey, the amount of fuel injected into the pre-chamber is vital to achieving stable combustion with ultra-lean air-fuel mixtures. Hence, the fuel injection and the mixture formation process inside the pre-chamber are investigated first by employing 1-D and 3-D CFD simulations, while the engine experiments provided the boundary conditions. Based on the simulation results, a correlation between the injected and the trapped fuel in the pre-chamber is proposed by theoretical scavenging models to estimate the air-fuel ratio in the pre-chamber at the ignition timing with high accuracy. Although the studies largely rely on thermodynamic engine experiments, the 1-D engine simulation implements the engine studies in estimating the mixture composition and heat transfer losses from the engine.

 

Bio

Ponnya Hlaing is a current Ph.D. candidate in Mechanical Engineering at the King Abdullah University of Science and Technology, supervised by Professor James W. G. Turner and Professor Hong G. Im. He graduated with a Master of Science in Marine Engineering degree from the University of Strathclyde, Glasgow, United Kingdom. He received his Bachelor of Engineering in Marine Engineering degree from the Myanmar Maritime University, Thanlyin, Myanmar. The author has a special interest in applications of pre-chamber-initiated combustion systems in the internal combustion engine of marine and heavy-duty engines.

Event Quick Information

Date
23 Aug, 2022
Time
01:00 PM - 02:00 PM
Venue
Room 5209, Level 5, Building 5