GB986031A - Thermal measuring apparatus - Google Patents

Abstract

986,031. Measuring temperature. BOEING CO. Feb. 4, 1963, No. 4526/63. Heading G1A. A thermo-electric device for measuring thermal parameters including radiant source temperatures, heating rate from any source (by radiation or convection) and the heat transfer coefficient between the source and the measuring device comprises two heating rate sensors of different sensitivities in thermal contact with a heat sink together with means for measuring the temperature of the latter (which must differ from that of the source) and for measuring the temperatures of each of the sensors at a point along its thermal gradient removed from the heat sink. In one embodiment (Figs. 1 and 2) the sensors comprise thin discs of constantan 10, 20, the peripheral edges of which are swaged into respective bores 14, 22 in a copper block 12 which, together with a heat exchanger 28, forms a heat sink the temperature of which is maintained at a predetermined value in relation to the temperature TS of the source S. Thermo-electric junctions 18, 26 are formed on the discs by means of copper conductors 16, 24 and a further temperature measuring device 15, (e.g. a thermocouple) is provided for measuring the heat sink temperature TO. for reference purposes. The Specification shows that, knowing the difference in the sensitivities of the two discs 10, 20 (through theoretical determinations and calibrations), a measurement of the thermo-electric junctions voltages e 1 , eg, and of the voltage e 0 of junction 15 is sufficient to calculate the source temperature Ts, the heating rate due to source and the heat transfer co-efficients between the source and each disc. The two heat sensors may be realized by a single constantan disc with the respective thermo-electric junctions located at different positions along the thermal gradient such as the junctions 36, 38 (Fig. 4) or by the junctions formed by the wires 46, 48 in the arrangement of Fig. 7. An arrangement for calibrating the instruments just described comprising means for heating a strip of constantan by passing a known electrical current through it (or through a spiral heating element associated therewith when it is of circular configuration) and then measuring the voltages produced by thermo-electric junctions formed at different positions on the strip is described with reference to Figs. 8 to 10 (not shown).