Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Gregory Thompson

Committee Co-Chair

Hailin Li

Committee Member

Arvind Thiruvengadam

Committee Member

Gregory Thompson

Abstract

Railways and mining operations are reaching new heights as end users break altitude barriers to increase efficiencies of their business and provide more goods. Diesel engines are the primary source of power used in both of these applications, whether it is for electricity generation or transportation of products. In particular, the copper and gold mining occurring in the Andes Mountains require diesel engines to operate at altitudes above 15,000 ft. At these altitudes the air density is low and the air temperature often falls below 0° F during the winter, providing a less than ideal atmosphere for the operation of a diesel engine. However, end users are demanding improved performance, fuel economy, and reliability as part of their push to optimize production and minimize costs.;As part of this effort to improve operation of diesel engines at high altitudes, engine manufacturers like Cummins are tailoring calibrations to oblige the customer. After making calibration modifications, a field test was conducted on a Komatsu 930E haul truck with a GE electric drive train at approximately 16,000 ft to assess the in-cylinder combustion events and compare them to an engine operating near 500 ft in a test cell.;Idiosyncrasies were identified for the Cummins QSK 60L engine incorporating a HPI fuel system. It was observed that the first cylinder on each bank was found to underperform when compared to the other instrumented cylinders. With respect to the maximum in-cylinder pressure, the greatest amount of cylinder-to-cylinder variation was witnessed during dynamic braking for both test; 4% during the test cell work and 12.97 % during the field test. The least amount of variation was witnessed during rated operation at 0.59 % and 0.22 % for the test cell data and field test data respectively. The calibration changes made by Cummins resulted in virtually no distinguishable differences in combustion while the engine was operating at rated conditions. The largest differences in combustion were observed during dynamic braking and dumping operating modes. The peak in-cylinder pressures were found to be approximately 26 % lower, on average, for both modes of operation at high altitudes. The most significant impact found on the combustion process from altitude effects was increased ignition delays. A linear correlation was found during the dumping operation that showed increased ignition delays which resulted in higher maximum heat release rates. The maximum heat release rate was found to increase approximately 41.47 %, on average, between the test cell data and the field test data. Despite a 26 % decrease in the maximum in-cylinder pressure observed during the field tests, the final heat release exhibited by each engine remained within 10 %. Improved thermal efficiencies were observed at high altitude compared to sea level for the low load operating points at 2 % and 11 %, on average, for the dumping mode and dynamic braking mode respectively which was consistent with the reduce PMEP values at altitude.

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