Temperature Detection Circuit

Two types of bridge circuits (unbalanced and balanced) are utilized in resistance thermometer temperature detection circuits. The unbalanced bridge circuit (Figure 9) uses a millivoltmeter that is calibrated in units of temperature that correspond to the RTD resistance. 

Figure 11 is a block diagram of a typical temperature detection circuit. This represents a balanced bridge temperature detection circuit that has been modified to eliminate the galvanometer. 

Figure 11 Block Diagram of a Typical Temperature Detection Circuit...

Temperature detection circuit operation is summarized below. 

Ambient temperature variations will affect the accuracy and reliability of temperature detection instrumentation. Variations in ambient temperature can directly affect the resistance of components in a bridge circuit and the resistance of the reference junction for a thermocouple. In addition, ambient temperature variations can affect the calibration of electric/electronic equipment. The effects of temperature variations are reduced by the design of the circuitry and by maintaining the temperature detection instrumentation in the proper environment. 

The density of the fluid, ambient temperature changes, and humidity are three factors which can affect the accuracy and reliability of level detection instrumentation. Level detection circuit operation is summarized below. 

Fig. lla-d. Transient absorption spectra of reaction intermediates (a-c) and final product (d) observed upon photopolymerization of a TS-6 crystal with a 308 nm laser pulse. Parameters are the temperatures and the delay times (At) between the laser pulse and spectra recording. In b and c the time window of the detection circuit was 100 ps. AOD is the difference of the optical densities after and before the UV-flash (from Ref. 

Coolant circuit water pressure and temperature (moisture) detection 12/307... 

Figure 4.25. Experimental configuration for optical pyrometry of shock temperatures induced in transparent minerals. Upon impact of projectile with driver plate, a shock wave is driven into the driver plate and then into the sample. Optical radiation from the sample is detected via six lens/interference filter channels and an array of six photodiodes. Signals from photodiode circuits are recorded on oscilloscopes operating in single sweep model. (After Ahrens et al. (1982).)...

Expansion valves for such circuits embody a mechanism which will detect the superheat of this gas leaving the evaporator (Figure 8.5). Refrigerant boils in the evaporator at Tg and p, until it is all vapour, and then superheats to a condition Tj, p, at which it passes to the suction line. A separate container of the same refrigerant at temperature Tj would have a pressure and the difference p is a signal directly related to the amount of superheat. 

Methanol oxidation on Pt has been investigated at temperatures 350° to 650°C, CH3OH partial pressures, pM, between 5-10"2 and 1 kPa and oxygen partial pressures, po2, between 1 and 20 kPa.50 Formaldehyde and C02 were the only products detected in measurable concentrations. The open-circuit selectivity to H2CO is of the order of 0.5 and is practically unaffected by gas residence time over the above conditions for methanol conversions below 30%. Consequently the reactions of H2CO and C02 formation can be considered kinetically as two parallel reactions. 

In a cryogenic experiment, one or several detectors are used for a definite goal for which they have been optimized. For example, in CUORE experiment described in Section 16.5, the sensors are the Ge thermistors, i.e. thermometers used in a small temperature range (around 10 mK). One detector is a bolometer made up of an absorber and a Ge sensor. The experiment is the array of 1000 bolometers arranged in anticoincidence circuits for the detection of the neutrinoless double-beta decay. Note that the sensors, if calibrated, could be used, as well, as very low-temperature thermometers. Also the array of bolometers can be considered a single large detector and used for different purposes as the detection of solar axions or dark matter. 

In the authors study, whenever the anode was reduced at a lower temperature, the cell open-circuit voltage (OCV) was only 0.8 to 0.9 V in humidified hydrogen even though no gas leakage was detected. 

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