Performance evaluation of dryer units used in diesel emission measurement systems

The gas dryer unit in an emission measurement system plays an important role in emission testing by removing the moisture out of the gas stream and thus reducing the dew point of the sample stream to a level which is required by the gaseous emission analyzers. Water vapor in the exhaust gas occupies considerable volume at high engine loads. In case of non-dispersive infrared (NDIR) and chemiluminescent analyzers, erroneous reporting of exhaust mass emissions could result in the presence of exhaust stream moisture due to interference effects. In addition to NDIR interference issues, an inaccurate determination of the volume displaced by water in the exhaust stream could report erroneous emission data. The current work evaluated the performance of six different types of chiller units employed in different emission measurement systems at West Virginia University. To estimate the performance of different chiller units, ambient air, dry zero air and humidified air were run through the chiller/dryer units. (Abstract shortened by UMI.)