Abstract: An apparatus for photo-acoustic measurement of a measurement target in a fluid flow comprises:—an ellipsoidal measurement chamber (3) having a first focal point and a second focal point; —a duct (6, 7, 8) configured to guide a fluid flow through the measurement chamber (3) along a first axis (X) through the first focal point; —light source means for generating an excitation light beam of modulated intensity; —means configured to pass the excitation light beam through the measurement chamber (3) along a second axis (Y), which is different from the first axis (X), such that the excitation light beam crosses the fluid flow at the first focal point and that the crossing of the fluid flow and the excitation light beam defines an excitation volume (4) within which the fluid flow is excited by the excitation light beam to generate acoustic waves; and —detecting means (5) arranged at the second focal point and configured to detect said acoustic waves, wherein the detecting means has no direct contact with the fluid f

Abstract: A diluter apparatus and a method for sampling of exhaust gas of engines, wherein the diluter has a primary capillary connected to a primary stabilizing chamber. The primary stabilization chamber is kept at a pressure below ambient by means of a vacuum pump connected to the primary stabilization chamber by means of a primary outlet duct and where dilution air in the primary stabilization chamber is introduced by means of a primary dilution air duct through a primary mixing tip, wherein there is provided an excess flowrate arrangement for providing an exhaust gas flowrate in excess of the sample flowrate in the capillary. Exhaust gas flowrate totally surrounds the capillary inlet tip, wherein the primary capillary is immersed in the exhaust gas flowrate with flowrate arrangement, and wherein the diluter receives the exhaust gas via said primary capillary.

Abstract: The present invention relates to a device used for the dilution of exhaust gas (diluter) and in particular for engines or vehicles. More particularly, the invention relates to a device and a method which may maintain a constant dilution ratio regardless of the exhaust gas backpressure in the exhaust line, without using any moving parts. The proposed diluter utilizes a very small fraction of the exhaust gas, sampled through a capillary duct, simply immersed to the exhaust flow, which is otherwise freely exhausting to the atmosphere. The sample flowrate through the capillary is achieved by maintaining a regulated underpressure at the capillary outlet. The diluted exhaust is then collected in a stabilization chamber, where temperature, humidity and residence time may be adjusted to condition the collected aerosol at will. Multiple capillaries and stabilization chambers may be cascaded to increase the dilution ratios.