Thermocouple-derived temperature

To obtain comparative temperature data, a Pt 13% - RhPt thermocouple provided by NASA Lewis Research Center was used to profile the propane flame at the Z = 50-cm downstream position. Comparison of the CARS and radiation-corrected thermocouple-derived temperature profiles is shown in Fig. 6. 

Sample and reference crucibles with separate heaters. Thermocouples with feedback to sample heater so that the power is varied to maintain AT= 0. Data output equipment to provide AE vs temperature curves, derivative curves and peak integration. Facility to vary atmosphere of sample. 

As the combustion proceeded, the bed surface regressed downwards and reached the first thermocouple (Tl), and after some time the second one (T2), and then the third one (T3). Since the time elapsed for the combustion front to regress between the thermocouples was measured (derived from temperature curves), and the distances between the thermocouples were fixed, the regression rate could be calculated. From the ratio between the air flow and regression rate the bed stoichiometric ratio could be obtained. 

Perry and Lee [28,29] offer an enhancement of QPA, based upon use of dual heat flux sensors and additional thermocouples in autoclave curing. This enhancement entails determining heat transfer properties during the cure, then using these properties in conjunction with PID regulatory control of autoclave temperature. Using the additional sensors, Perry and Lee employ an on-line Damkohler number in lieu of the second time-derivative of temperature to avoid exothermic thermal runaway within the prepreg stack thermoset resin. The Damkohler number is defined as ... 

The main source of uncertainty was the absolute temperature measurement, which was made with a platinum, platinum-rhodium thermocouple, calibrated by the National Bureau of Standards to i but thought to be accurate to 1 ° G. AZ/q was obtained l y substituting the experimentally determined equilibrium constants and the spectroscopically derived free energy functions into equation 3.1.6. The results obtained are shown in Table 3.2.1. 

In the first approach, the temperature-time profiles of the combustion wave are measured using thin thermocouples (Zenin et al, 1980 Dunmead et al, 1992a,b,c). In the work of Zenin et al (1980), 7-/im-diameter microthermocouples protected by a layer of boron nitride were used. The temperature-time profiles were analyzed using the one-dimensional heat conduction equation with heat generation (see Section IV,A, 1) taking numerical derivatives of the spatial temperature distribution. An implicit assumption in the analysis is that the combustion wave is stable and planar at both the macro- and microscopic scales. 

The Pt catalyst was mounted on a copper block and could be translated, tilted and rotated by means of a manipulator fitted with a differentially pumped rotary feedthrough. The Pt foil (Advent, purity > 99.99%) could be resistively heated. The mounting allowed to work in the temperature range 300-1600 K using direct sample heating with a proportional-integral-derivative (PID) control unit. The temperature of the catalyst was measured by a Ni-NiCr thermocouple spot welded to the Pt-foil. Clean platinum surfaces could be obtained by applying several cycles of Ar" " ion... 

Heat is lost from the surface by conduction through the susceptor and mount, by forced convection of gas over the substrate, and by radiation to the reactor walls, provided the temperature of the substrate is sufficiently high. Endothermic chemical reactions also result in heat loss from the film. The substrate temperature is monitored with a thermocouple or an optical pyrometer and controlled using a traditional proportional-integral-derivative (PID) controller and power source. 

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