GB2291197A

GB2291197A - Two/three dimensional temperature sensor

Info

Publication number: GB2291197A
Application number: GB9412655A
Authority: GB
Inventors: Alan Keith Wood; Yusef Judeh; Mingzheng Yue
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-06-23
Filing date: 1994-06-23
Publication date: 1996-01-17
Anticipated expiration: 2014-06-23
Also published as: GB9412655D0; GB2291197B

Abstract

A sensor for the determination of two and three dimensional temperature distributions in static or moving media is composed of interconnected wires 2, 3 in the form of a mesh, such that the connection points of the mesh constitute thermocouple junctions. Measurement of the voltages around the periphery of the mesh, coupled in some cases with the use of reference junctions, allows the temperature at the junctions in the mesh to be calculated by the use of Kirchhoff's Laws. The mesh can be supported around its periphery in a thermally and electrically insulating frame 1. Electrical connection at the junctions is ensured by such methods as soldering or spot welding. The mechanical strength of the mesh can be improved by weaving or winding the wires of which the mesh is comprised. Parallel wires may be of the same metal, e.g. chromel or alumel, so that the intersections form junctions of dissimilar metals. <IMAGE>

Description

Two/Three Dimensional Temperature Sensor This invention relates to a device that can be used to measure 2 and 3 dimensional thermal images in stationary or moving media.

Often, for the purposes of experiment and process control, it is necessary to measure accurately the temperature fields within a medium. Normally, due to the construction of the temperature measuring devices used this is difficult due to errors related to such things as conduction and friction heating effects in the case of single thermocouples and calibration in the case of infra-red pyrometers.

According to the present invention there is provided a system of interconnected wires, in the form of a 2 or 3 dimensional mesh with or without reference junctions, the wires being such that the individual junctions of the mesh constitute individual thermocouple junctions. Measurements of voltage at the periphery of the mesh can be taken such that the electro-motive-force(emf) generated at each of the individual junctions, and hence the temperature of the individual junctions, can be determined. The mesh structure of the system is such that it has considerable mechanical strength even when the wires used are relatively small in diameter. The small size of the resulting junctions yields a system that minimises any effects on local flows when the temperature of flowing fluids are being investigated and responds rapidly to local variations in temperature.Conduction losses along the mesh are small due to the wire diameter being small.

The mesh can be supported in a suitable frame 1 which is both electrically and thermally insulating. The junctions of the mesh need to in good electrical contact this being achieved using methods such as soldering(care being taken to remove excess solder from the junction in order to maximise the sensitivity of the junction) or spot welding. For added strength, the junctions can be woven or wound.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing, Figure 1, in which a typical 2x4 mesh is shown. In the example, parallel wires are of the same metal, for example Chromel or Alumel, the mesh being such that the intersections are intersections of dissimilar metals 2 and 3. Typical wire diameters are of the order of 0.3mm, meshes of this design being sufficiently strong to be placed in flowing polymer melts (flow rate 70cm3s', apparent viscosity 800 Ism2).

The resulting peripheral voltages that are measured can be analysed using Kirchhoff's Laws in order to determine the emf generated at each junction and hence, with calibration data for the mesh or knowledge of the relationship between emf and temperature for the particular combinations of wires (available in standard tables), the temperature of the individual junctions can be obtained.

Claims

1. A system of interconnected wires, in the form of a 2 or 3 dimensional mesh, the wires being such that the individual junctions of the mesh constitute individual thermocouple junctions.

2. A system of interconnected wires as claimed in Claim 1 with or without reference junctions.

3. A system of interconnected wires as claimed in Claim 1 where measurements of voltage at the periphery of the mesh can be taken such that the electro-motiveforce generated at each of the individual junctions, and hence the temperature of the individual junctions, can be determined.

4. A system of interconnected wires as claimed in Claim 1 where the mesh structure of the system is such that it has considerable mechanical strength.

5. A system of interconnected wires as claimed in Claim 1 where errors in temperature measurement related to heat conduction and friction heating (in the case of flowing media) are small.

6. A system of interconnected wires as claimed in Claim 1 where electrical connection at the junctions of the mesh is ensured by methods such as spot welding or soldering and where the junctions are woven or wound.