Experimental Measurements of the Independent Effects of Dilution Ratio and Filter Temperature on Diesel Exhaust Particulate Samples

A dilution mini-tunnel is described that allows collection of diesel exhaust particulate samples with independent control of the dilution ratio and the sample filter temperature. This tunnel was used to determine the individual effects of these two tunnel operating variables on the samples collected from a single-cylinder indirect-injection test engine run at constant speed and load. Either increasing the filter temperature at fixed dilution ratio or increasing the dilution ratio at fixed filter temperature resulted in a decrease in total particulate mass. These changes in total mass were attributed to changes in the soluble fraction of the particulate sample.