A prototype dilution system was developed. The DownToTen (DTT) system consists of one (hot or cold) porous tube dilutor, one catalytic stripper (exchangeable), one cold porous dilutor and an additional dilution (if required). The DTT dilution system was found to be a good vehicle to base the further activities of the project.
Synthetic exhaust bench tests demonstrated that the system is characterized by low non-volatile particle losses (with the exception of the catalytic stripper) and that the hot system appears to be artefact free at 10 nm against sulfuric acid – water nucleation.
Standardised penetration tests performed confirmed the low losses of the DTT system
Evaluation of the prototype system with dedicated experiments on chassis dynamometer using real exhaust showed that the penetration efficiency of the DTT system is close to the PMP system.
Computational fluid dynamics simulations (CFD) provide detailed insights on the air flow through the porous medium, and the mixing of the dilution air and the sample flow.