Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
  • G01J5/12—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using thermoelectric elements, e.g. thermocouples

Definitions

• the present invention relates to an instrument for mea ⁇ surement of the radiant asymmetry in the thermal field.
• the instrument comprises a sensor device for heating, cooling and temperature measurements, and a control and measuring device for determination of the radiant exchange to the environment of the sensor.
• the radiant asymmetry is defined as the difference between the plane radiant temperature of two opposite sides of a small plane element.
• thermo -. elements On top of each of the insulating surfaces a black, highly thermally conductive plate has been, affixed. The two last surfaces have been interconnected by one or more thermo -. elements. On top of that there are thin radiation permeable foils, between the foils and the black surfaces there are small cavities with stagnant air.
• thermoelements When a radiant asymmetry arises perpendicularly to the black surfaces the two opposite surfaces will attain dif- ferent temperatures. The size of this difference, which can be measured by the thermoelements, is a measure for the radiant asymmetry.
• the disadvantage of this instrument is the thin transparant foils which - especially in undustry environments - quickly change their transmission ability for radiation and by that the sensitivity of the instrument.
• a discription of a sensor is given; this sensor consists of two black and two polished square surfaces at the same level. The surfaces are inter ⁇ connected by a thermobattery which makes it possible with good accuracy to measure the temperature difference which arises between the polished and the black elements when the surface is exposed to a radiant temperature different from the air temperature.
• thermobattery which makes it possible with good accuracy to measure the temperature difference which arises between the polished and the black elements when the surface is exposed to a radiant temperature different from the air temperature.
• the instrument consists of two black surfaces with a good conductivity, each of which in con ⁇ tact with both an electric heating element and a tempera ⁇ ture sensor. The surfaces are located on each side of a third thermally insulating surface.
• the connected control- and measurement instrument assures a constant temperature of the two black surfaces and measures the necessary effect for maintaining the constant temperature. The difference of the two measured effects is an indication of the asymmetry in the thermal field.
• This instrument thus measures the asymmetry by the sum of the convection - and the radiant field perpendicularly on the plane of the sensor and not • the radiant asymmetry.
• the aim of the present invention is to create an instru- ment by which it is possible to measure the thermal radiant asymmetry without the disadvantages and sources of error mentioned above.
• the sensor consists of two parallel and from eachother thermally insulated plate elements the other sides of which are black.
• the elements are interconnected by a pel-: tier-element as well as by a thermo sensor which is able to measure the temperature difference between the two elements.
• the matching control and measuring instrument is adapted to keep the two elements at the same temperature as the peltier-element cools the warmer element and heats the cooler one until the thermo sensor indicates that the temperature difference between the two is 0.
• the effect per area unit of the elements needed to kee the two elements at the same temperature when exposed to an asymmetric radiation field can be measured, and it will equal the radiation flux perpendicularly on the plane of the elements and is thus equivalent to the radiation asymmetry at the place of the sensor.
• Figure 1. shows a sensor for measurement of the radiant asymmetry.
• Figure 2. shows a sensor for measurement of the absolute radiant temperature.
• the two plate elements 1 and 2 have a surface with an emission figure as near as possible to 1 for the wavelength the asymmetry of which you want to measure. Between the two elements two peltier-elements 3 and 4 are located; the thickness of these peltier-elements are equal to the distance between the two plane elements. The space between 1 and 2 is filled with a good heat insulating material 5.
• This potential difference is used, via a simple already known electronic control, to impose on the other peltier-element an electric current with an intensity and direction which reduces the temperature difference between 1 and 2 to 0.
• the electric current necessary to keep 1 and 2 at exactly the same temperature is a direct measure for the radiant asymmetry between the two half spaces limited by a plane through the middle of the sensor parallel with 1 and 2; or otherwise said this current is a measure for the radiation flux perpendicularly on 1 and 2. If the sensor, apart from an asymmetric thermal radiation field, is exposed to an air velocity the temperature of all the sensor can be changed but this will not influence the measurement because the radiation flux and thus the necessary flux through 4 is independent of the air velocity.
• a sensor according to fig. 1 can be used for measure ⁇ ment of the radiant asymmetry between the two half spaces but not for measurement of their absolute radiant tempera- ture. According to the invention this can be achieved by the sensor shown on the sketch fig. 2.
• This sensor consists of three parallel elements 6, 7 and 8 made of a heat conduc ⁇ tive material f.inst. aluminium.
• the space between the ele ⁇ ments equals the thickness of the peltier-elements.
• the space between the elements is filled by a heat insulating material 9.
• the element in the middle 6 has a diameter which is about 4 times bigger than the diameter of 7 and 8.
• 6 has a radiation reflecting surface which causes 6 to adapt the air temperature.
• This air temperature can in an already known way be determined f.inst. by a temperature dependent resistor 10 coupled in a bridge circuit.
• a temperature dependent resistor 10 coupled in a bridge circuit.
• At the middle of each side of 6 two peltier-elements 11 and 12, and 13 and 14 have been located, all covered by the radiation absor- bing elements 7 and 8.
• By means of the two sets of peltier- elements as explained above 7 and 8 respectively will be kept at the same temperature, i.e. the air temperature.
• the intensity and the direction of the current through the peltier-elements 12 and 14 is a measure for the deviation of the two plane radiant temperatures from the air tempera ⁇ ture.
• the sum of the two currents is a measure of the radiant asymmetry.
• the correlation between the current through the peltier-elements 12 and 14 and the deviation of the plane radiant temperatures from the air temperature can either be calculated on the basis of the physical data of each component or on the basis of the calibration of the known radiant asymmetric fields.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Radiation Pyrometers (AREA)

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• 1981
  • 1981-12-28 DK DK577981A patent/DK147087C/da active
• 1982
  • 1982-12-27 EP EP19830900185 patent/EP0097682A1/en not_active Withdrawn
  • 1982-12-27 WO PCT/DK1982/000116 patent/WO1983002324A1/en unknown

Non-Patent Citations (1)

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