This is a brief overview of some applications of the DMS500. Further information can be found in the applications area of the website.

Measurement of Diesel Passenger Car emissions with & without a DPF.

The plot shows data from two consecutive vehicle tests; with and without a DPF (Diesel Particulate Filter). The real time mass emission displayed is calculated from transient spectral data. The data allow precise identification of points during the cycle which give rise to significant PM emissions, so development and calibration efforts can be targetted at those conditions.

These two plots show the particulate spectra corresponding to the deceleration from the extra urban phase, with and without the DPF.

With the DPF there is evidence of accumulation mode breakthrough at high space velocities.

Without the DPF, the emission is about two orders of magnitude higher during the cruise than with the DPF. During the deceleration the combustion mode is replaced by a nucleation mode.

The DMS500 is also available with a heated sampling system. This allows sampling either side of the DPF when coupled with the two stage dilution system supplied as standard with the instrument. The dilution system and heated line avoid the requirement for a CVS tunnel. This can be particularly useful during DPF development where the ability to adjust the dilution in real time can take account of changing DPF performance and aerosol concentration - for example during temperature related leaks.

Download Application Note DMS05 : Diesel Particulate Filter Measurement with a DMS500 (pdf 1220kB) here

Ambient Measurements

The DMS500 brings transient capabilities to ambient pollution measurement. The instrument is capable of unattended operation with scheduled sampling and autozero. External devices such as cameras can be triggered when the particle concentration exceeds a preset level. The rapid response ensures that individual vehicle events can be isolated for study.

The sample data above shows a roadside ambient spectrum produced by predominantly gasoline traffic: an aged nucleation mode around 30nm is accompanied by a lower concentration accumulation mode around 100nm. The first highlighted event corresponds to a vehicle driving by, producing a transient increase in the particle concentration.

The second highlight shows the pasage of a Diesel vehicle under load, producing a markedly larger aerosol mode. This is shown in a still from an animation, below; the increased accumulation mode concentration persists in the environment for a little while.

Heavy Duty Diesel Measurements

The DMS500 is valuable for testing heavy duty diesels. Highly dynamic cycles, such as the FTP Transient Cycle, emphasize the instrument's fast time response; and its built-in dilution facilities allow particulate measurements without a full flow dilution tunnel. The fast response combined with the full spectral resolution allow measurement of short lived events such as a distinct large particulate mode (around 150nm) produced only during periods of very high torque demand.

Three different particulate modes produced at different conditions are shown in the extract from the FTP transient cycle, above. The fuel shut off at ~490s causes the typical ~50nm combustion mode to be replaced with a nucleation mode. A high torque demand then produces the larger combustion mode peaking initially at ~135 nm. As the torque decreases, this mode decreases in size, to ~115 nm. The reduction in size will be associated with a large drop in mass emission at this point, although the number remains approximately constant.

Gasoline Direct Injection

Gasoline direct injection particle emissions are significant and increasingly of interest. The particle emissions are particularly sensitive to calibration and ambient conditions. By providing spectral data the DMS makes it possible to address specific issues such as mode switching between stoichiometric and lean operation, where transient high mass emissions are observed; shown above in the first 200s of the New European Drive Cycle.

View the whole cycle data here (pdf 442kB).

Cambustion supply an Add-In for Microsoft Excel to automate the presentation of DMS500 data as shown on this page. Click here for more information

Contact Cambustion for more information and prices.