This paper discusses the measurement of thermal efficiency for natural gas-fueled engines and the resulting uncertainty. Two methods for determining thermal efficiency are described in detail. For each method, the sources of uncertainty are identified and quantified, and an estimate of the overall uncertainty is calculated. The analysis indicates that a thermal efficiency calculation that uses a mass fuel flow rate measurement directly as a basis for the energy input rate provides less uncertainty than the other method that uses a volumetric flow measurement.

This content is only available via PDF.
You do not currently have access to this content.