Engineered Approach to Reach Emissions Targets on a Worthington LTC Engine
Through a variety of projects, the Pipeline Research Council International (PRCI) and its member companies have sponsored research and analysis of engine modeling, turbocharger modeling and the modeling of the interaction between the engine and turbocharger. The K-State NGML and AETC collaborated on the continual refinement of these techniques over the last 10 years in support of a number of engine upgrades. Recently, Tennessee Gas Pipeline came to both parties with a particularly challenging problem: pure turbocharging of a pump scavenged Worthington LTC without making any modifications to major iron such as the lines, pistons or heads. As an indicator of the challenge, significantly funded attempts to turbocharge the engine had not succeeded. When the conversion was attempted with modifications to the cylinders and pistons, the degradation in performance due to loss of compression ratio and scavenging efficiency was unacceptable. A sound and robust engineering approach to upgrade this low BMEP engine was implemented. The prior engineering tools were upgradedto more accurately simulate the blowdown event. This offered a much better estimate of energy available to the turbocharger which defines its ability to self sustain. Based on this and previously developed dimensionless analysis methods, the team developed a comprehensive turbocharger specification. Using that specification, the turbocharger provider developed a special design and then optimized it at the NGML to meet that specification. With the precisely matched turbocharger self-sustaining in the field at a relatively low boost pressure, the turbocharged engine system achieved an emissions limit margin with acceptable combustion stability throughout the operating range.