SYSTEM FOR DETERMINING EXHAUST GAS VOLUME

• US 20120180548A1
• Filed: 09/28/2010
• Published: 07/19/2012
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Bosselmann, Thomas
• Granted Patent: US 8,875,558 B2
• Time in Patent Office: Days
• US Class Current: 73/23.31
• CPC Class Codes: G01F 1/6884 making use of temperature dependence of optical properties
• CPC Class Codes: G01P 5/10 by measuring thermal variables
• CPC Class Codes: G01P 5/26 by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave

Abstract

A system is disclosed, including: a plurality of Bragg gratings distributed in positions transversely to the direction of flow of an exhaust gas in an exhaust gas channel of the device; an optical wave guide structure including at least one optical wave guide and in which the Bragg gratings are embodied; a heating device arranged adjacently to the Bragg gratings and through which the Bragg gratings are subjected to heat, or a cooling device arranged adjacently to the Bragg gratings, through which the Bragg gratings are subjected to cold; at least one light source for irradiating light into the optical wave guide structure; and at least one signal processing device which determines, from light backscattered from Bragg gratings in the optical wave guide structure against its original direction of diffusion, the speed of the flow of the exhaust gas.

Claims

1. A system for determining exhaust gas volume for a stationary or mobile device, comprising:

a number of Bragg gratings arranged distributed at specified positions transverse to a direction of flow of an exhaust gas in an exhaust gas duct of the device;

an optical waveguide structure, in which the Bragg gratings are embodied, the optical waveguide structure including at least one optical waveguide;

at least one light source configured to beam light into the optical waveguide structure;

at least one signal processing device, configured to establish a speed of flow of the exhaust gas along a course of the optical waveguide structure from light scattered back from the Bragg gratings in the optical waveguide structure opposite to its original direction of propagation; and

at least one of

a heating device, arranged adjacent to the Bragg gratings, through which the Bragg gratings are heatable to a temperature above the exhaust gas temperature, wherein a heat power to be output by the heating device is able to be adapted to the exhaust gas temperature, and

a cooling device arranged adjacent to the Bragg gratings by which the Bragg gratings are coolable to a temperature below the exhaust gas temperature, the at least one signal processing device being configured to determine a flowing exhaust gas volume from the established flow speed of the exhaust gas determined along the course of the optical waveguide structure.

2. The system as claimed in claim 1, wherein the optical waveguide structure includes optical waveguide sections crossing each other.

3. The system as claimed in claim 2, wherein an optical waveguide network is embodied by the optical waveguide sections crossing one another.

4. The system as claimed in claim 3, wherein the optical waveguide network embodied by a single optical waveguide.

5. The system as claimed in claim 1, wherein the optical waveguide structure includes an optical waveguide running in a spiral shape in which the Bragg gratings are arranged one behind the other.

6. The system as claimed in claim 1, wherein the heat power of the heating device, starting from an initial value, is able to be automatically increased step-by-step until the signal processing device identifies unique temperature differences along at least one optical waveguide, or that the cooling device comprises at least one pipe in which at least on optical waveguide is arranged and around which a coolant is able to flow.

7. The system as claimed in claim 1, wherein the heating device or cooling device is arranged along the at least one optical waveguide of the optical waveguide structure and adjacent to said waveguide.

8. The method as claimed in claim 7, wherein a level of heating or cooling power per unit length of the optical waveguide is able to the output by the heating device or cooling device.

9. The system as claimed in claim 1, wherein the Bragg gratings have different grating periods along at least one optical waveguide and a broad spectrum of light is able to be beamed into these optical waveguides via a light source, or that the Bragg gratings have the same grating periods along at least one optical waveguide, pulsed, monochromatic light is able to be beamed into these optical waveguides by way of a light source and a delay time of the backscattered light is able to be detected and evaluated by way of a signal processing device.

10. The system as claimed in claim 1, wherein the at least one optical waveguide and the heating device are arranged in or on a rigid support element, the form of which defines the course of the optical waveguide in the exhaust gas duct.

11. The system as claimed in claim 10, wherein the optical waveguide is arranged in a replaceable fashion in a cavity of the support element and is protected from direct contact with the exhaust gas by way of the support element.

12. The system as claimed in claim 9, wherein the carrier element simultaneously forms the heating device.

13. The system as claimed in claim 1, further comprising a sensor to determine a concentration of a pollutant in the exhaust gas.

15. A method of using the system of claim 1 for measuring exhaust gas emissions from stationary and mobile devices, comprising:

establishing a pollutant emission of the device on the basis of an exhaust gas volume determined and at least one measured value for a concentration of a pollutant in the exhaust gas.

16. The system of claim 1, wherein the system is for determining exhaust gas volume for a boat.

17. The system as claimed in claim 10, wherein the carrier element simultaneously forms the heating device.

14. A method for determining a volume of exhaust gas of a stationary or mobile device, comprising:

at least one of

heating up Bragg gratings to a temperature above an exhaust gas temperature, a heat power to be emitted by a heating device being adapted during the heating to the exhaust gas temperature, or

cooling down the Bragg gratings to a temperature below the exhaust gas temperature;

establishing a flow speed of the exhaust gas along the course of an optical waveguide structure, when coupling light into the optical waveguide structure, by light scattered back from the Bragg gratings against its original direction of propagation; and

determining the volume of the exhaust gas flowing through the exhaust gas duct from the established flow speed.