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Continuous measurement of dilute exhaust gas from the CVS system, which provides gas concentrations proportional to the mass of emissions, is widely used for modal mass analysis of exhaust emission. Recently, exhaust gas flow rate measurement devices have become commercially available. Cost-effective raw exhaust modal mass analysis will be feasible with a combination of the new exhaust gas flow meters and fast response gas analyzers. In this paper, the benefits of raw exhaust modal mass measurement and the impacts of response time for the gas analyzer on the accuracy of exhaust mass calculations are discussed. Gas analyzer system with enhanced speed of response has been developed by hardware modification applied to the existing conventional bench system. De-convolution or inverse digital filter techniques that compensate the delay in the exhaust sampling system and the gas analyzer are described with comparisons to the hardware modifications.

This paper presents a technique for examining “Goodness of Fit” of polynomial least square curves using “errorless” data. (The errors in “real world” data tend to mask a polynomial curve's lack of fit). A method of assessing the “quality” of real data before attempting to fit a curve to the data is also presented. If data “quality” proves satisfactory, a cubic spline curve can be generated which provides a much better fit to the data than can ever be attained using polynomial curves.