Particulate deposit avoidance and probe positioning
View Patent ↗A perforated mixing plate and is fluid passage are used in conjunction with a dilution tunnel to prevent particulate matter from collecting on the sampling system components. An inlet of a sampling probe is offset from the centerline of the dilution tunnel to a location corresponding to an average particulate matter concentration along a flow profile of a sample mixture to reduce the length of the dilution tunnel.
1. An exhaust sampling system for measuring particulate matter comprising:
an exhaust gas source and a dilution gas source;
a dilution tunnel having an upstream side in fluid communication with the exhaust gas and dilution sources, the exhaust gas source having particulate matter; and
a mixing plate arranged in the dilution tunnel and having an orifice enhancing mixing of the exhaust gas and dilution sources to produce a sample mixture, and multiple perforations arranged about the orifice, the perforations permitting a flow through the mixing plate in addition to the flow through the orifice that prevents the particulate matter from collecting on the mixing plate.
2. The system according to claim 1 , wherein the mixing plate is arranged downstream from the exhaust gas source.
3. The system according to claim 1 , wherein the dilution tunnel includes an a wall spaced from the dilution tunnel providing a fluid passage, the fluid passage for carrying a fluid in a direction generally parallel with a flow direction of the sample mixture within the dilution tunnel.
4. The system according to claim 3 , wherein the wall is arranged radially inboard of the dilution tunnel.
5. The system according to claim 3 , wherein the fluid passage is generally annular and including an exit arranged between the dilution tunnel and the wall.
6. The system according to claim 5 , wherein the exit is bounded by the dilution tunnel and wall, the exit being generally annular.
7. The system according to claim 1 , comprising a sampler including a probe that is arranged in the dilution tunnel downstream from the mixing plate, the probe receiving the sample mixture.
8. The system according to claim 7 , wherein the sampler includes a filter having a filter element for collecting particulate matter.
9. The system according to claim 7 , wherein the dilution tunnel includes a centerline, and the probe includes an inlet that is offset from the centerline by a predetermined amount corresponding to an average particulate concentration location along a profile of the sample mixture.
10. An exhaust sampling system for measuring particulate matter comprising:
an exhaust gas source and a dilution gas source;
a dilution tunnel having an upstream side in fluid communication with the exhaust gas and dilution sources, the exhaust gas source having particulate matter;
a wall spaced from the dilution tunnel providing a fluid passage, the fluid passage providing a fluid along an inner surface of the dilution tunnel, and an exit providing the fluid in a flow direction generally parallel with the inner surface; and
a mixing plate arranged in the dilution tunnel and having an orifice enhancing mixing of gases from the exhaust gas and dilution sources to produce a sample mixture.
11. The system according to claim 10 , wherein the wall is arranged radially inboard of the dilution tunnel.
12. The system according to claim 10 , wherein the fluid passage is generally annular and the exit is arranged between the dilution tunnel and the wall.
13. The system according to claim 12 , wherein the exit is bounded by the dilution tunnel and wall, the exit being generally annular.
14. The system according to claim 10 , wherein the wall adjoins the mixing plate on a downstream side.
15. The system according to claim 14 , wherein the wall is arranged radially outward from the orifice.
16. The system according to claim 15 , wherein the mixing plate includes perforations arranged between the orifice and the wall.
17. An exhaust sampling system for measuring particulate matter comprising:
an exhaust gas source and a dilution gas source;
a dilution tunnel in fluid communication with the exhaust gas and dilution sources, the exhaust gas source having particulate matter; and
a wall spaced radially inwardly from the dilution tunnel providing a fluid passage, the fluid passage providing a fluid along an inner surface of the dilution tunnel, and an exit providing the fluid in a flow direction generally parallel with the inner surface, the wall arranged downstream from the exhaust gas source.
18. The system according to claim 17 , comprising a sampler including a probe arranged in the dilution tunnel downstream from the wall, the probe receiving a sample mixture of gases from the exhaust gas and dilution sources, the dilution tunnel including a centerline, and the probe includes an inlet that is offset from the centerline by a predetermined amount corresponding to an average particulate concentration location along a profile of the sample mixture.