Thermocouple probe measurements

An Omega model HH22 type J-K digital thermometer, connected to a type K thermocouple probe inserted directly into the flask, was used to measure the temperature. 

Quartz probes fitted with thermocouples to measure the temperature, and follow the movement of the sample. Linked transducer, i.e. a linear variable density transformer to sense the probe movement and produce a related electrical signal. Sample furnace, programmers and various output devices. 

The temperature of molten polymer process streams is commonly measured using a thermocouple positioned through a transfer line wall and partially immersed in the polymer stream. Process stream temperature measurements that use an exposed-tip thermocouple, however, can be misleading since the temperature of the thermocouple junction is a balance between the heat transferred from the polymer stream and from the thermocouple assembly [39]. Due to the low heat transfer rate between the polymer and the exposed tip and the high thermal conductivity of the thermocouple sheath, the temperatures measured can be different by up to 35°C depending on conditions. Extrudate temperatures, however, can be accurately measured using a preheated, handheld thermocouple probe. This method minimizes thermal conduction through the probe sheath. 

A handheld thermocouple measurement device and an IR temperature sensor are very important to have for understanding the performance of the extruder. These devices have been discussed previously in this chapter. In many of the case studies presented later, the extrudate temperature was measured by immersing a handheld thermocouple probe into the extrudate. The entire probe length is immersed or draped in the extrudate to minimize heat conduction to cooler parts of the probe. The highest temperature measured is the reported value. If it is unsafe to measure the extrudate temperature using a handheld device, then an IR temperature sensor is used to estimate the discharge temperature. 

The p-jump unit produced by Hi-Tech Limited (PJ-55 pressure-jump) is based on a design by Davis and Gutfreund (1976) and is shown in Fig. 4.7, with a schematic representation in Fig. 4.8. A mechanical pressure release valve permits observation after 100 /us. There is no upper limit to observation time. Changes in turbidity, light absorption, and fluorescence emission can be measured in the range of 200-850 nm. The PJ-55 is thermostated by circulating water from an external circulator through the base of the module. The temperature in the cell is continuously monitored with a thermocouple probe. A hydraulic pump assembly is used to build up a pressure of up to 40.4 MPa. A mechanical valve release causes the pressure build-up to be applied to the solution in the observation cell. The instrument has a dead time of 100 /us. A fast response UV/fluorescence... 

In contrast to the use of large Sf ratios, where attention is focussed on the wall of the tube, Wood and Wise [62, 63] have used short tubes to determine j for the material simulating the end plate. They investigated the recombination efficiency of several metals for H atoms. In the later study [63], their terminal probe was in the form of a heated spiral filament of the metal under investigation. The decrease in energy necessary to maintain the filament at constant temperature was measured and assumed to be proportional to the atom concentration at the cross-section occupied by the filament. The method is preferable to the use of thermocouple probes, whose change in temperature might affect the atom decay profiles. Wood and Wise attribute differences in their results obtained... 

In early tests, the temperature of the emulsion was measured by thermocouples. The thermocouples were removed for later tests, because no significant exotherm was observed and because tube plugging sometimes occurred near the thermocouple probe. 

Among the advanced techniques employed to follow the cure reaction, Fiber Optic Raman Spectroscopy has been an effective tool. By this technique, both the temperature build-up and the cure advancement of AroCy L-10 could simultaneously be followed. The local temperature of the sample, determined by Ra-man-Stokes and anti-Stokes scattering of a reference peak correlated well with the temperature measured using a thermocouple probe. The extent of cure could be monitored using either individual peaks associated with the reactant or product or by using the entire spectrum [104]. 

Perform three (3) loaded chamber heat penetration studies to verify that the temperature distribution is uniform for the load configuration, and that all measured points within each load configuration receive thermal treatment sufficient for depyrogenation and sterilization. A Kaye Validator equipped with thermocouple-probed containers shall be used to provide an equal representation among layers in the chamber. 

FIGURE 16.31 Thermocouple probes for measuring temperatures of flowing fluids. 

Unlike intrusive thermocouple probes, optical techniques of temperature measurement do not disturb the combustion process (see Chapter 12). Sodium line-reversal is an optical technique first used for measuring flame temperature by Kurlbaum [3] as early as 1902. Although this technique has been improved through the years, line-reversal methods use line of sight optics... 

High Ambient and Off-Gas Temperatures Water cooling was employed for the launch and receiver modules, the pathlength control probes, and the break flange. A total of six thermocouples were used during the first several months of operation to monitor the thermal conditions of the optics modules and probes. Thermocouple data was recorded on a separate data logger located near the measurement location. Each module had an internal thermocouple, a thermocouple to measure enclosure water outlet temperature, and a thermocouple to monitor the water outlet temperature of each probe. 

Having estimated the optimum primary drying parameters, a pilot study should be performed. It is not good practice to carry out such a study either in an incompletely filled drier or by filling up shelves partly with empty vials. The reliability of pressure and temperature measurements should be checked at this stage. It has sometimes been found that the (apparent) product temperature exceeds the shelf temperature. Since this is an obvious physical impossibility, such an anomaly is due to faulty calibration of the thermocouple probe. 

Experimental set up of the type A stack is shown in Fig. 2 (a). Gas manifolds for fuel and air for inlet and out-let were fixed to the stack with the thermocouples to monitor stack temperature and gas out let temperatures. The discharge characterization was investigated by using a Parstat 2273 (Princeton Applied Research) in DC 4 point probe measurement. The Ag wire was used for collecting current from anode and cathode sides, which were both fixed by Ag paste. Hydrogen (humidified by bubbling water at room temperature) was flowed at the rate of 100 mL min and the air was flowed at the rate of 500 mL min at the cathode side. 

We wish to estimate the dynamics of a cold thermocouple probe suddenly placed in a hot flowing fluid stream for the purpose of temperature measurement. The probe consists of two dissimilar metal wires joined by soldering at the tip, and the wires are then encased in a metal sheath and the tip is finally coated with a bead of plastic to protect it from corrosion. Take the mass of the soldered tip plus plastic bead to be m, with specific heat Cp. Denote the transfer coefficient as h. 

Until recently, temperature measurements in microfluidic systems were limited to measures of bulk fluid temperature at the inlet and outlet of microfluidic sections or simply measurement of the substrate temperature. With regard to local temperature measurements, thermocouple probes provide highly accurate measures of fluid and/or substrate temperature with excellent temporal response. However, thermocouples can often be physically intrusive and generally suffer from poor spatial resolution since most probes have a characteristic size of several micrOTs or more. Alternatively, microfluidic devices can be fabricated with integrated microscale resistance temperature detectors (RTDs s) embedded in the substrate with spatial extents on the order of a few microns [13]. Micro-RTDs overcome the intrusiveness issues of thermocouples however, their fabrication can be quite complex and RTDs still suffer from poor spatial resolution which limits their ability to resolve local thermal... 

Watanabe MS, Kakuta N, Mabuchi K, Yamada Y (2005) Micro-thermocouple probe for measurement of cellular thermal responses. In Proceedings of the lEEE-EMBS 27th annual international conference. Shanghai, China, pp 1-4... 

AU the modern scientific microwave units have the capabiUty to measure temperature during the course of a reaction. This can be done remotely using an infrared sensor located in the waU or the bottom of the microwave cavity. In many cases it is also possible to record the temperature inside a reaction vessel using a fiber-optic probe or thermocouple. Pressure measurement is also possible in many cases. The contents of a reaction mixture can be stirred by means of a magnetic stir plate located beneath the microwave cavity and a Teflon stir bar in the vessel. 

It is known that the attenuation and the dielectric constant of AZS material increases as the temperature of the AZS increases, so it was necessary to make similar fundamental measurements of hot AZS. This was done using a small kiln. The top cover of the kiln was removed and replaced with blocks of AZS to be tested at high temperature. Thermocouple probes were placed at the bottom of the test blocks and at the top of the test blocks. Insulation material covered the blocks except where probe antennas were mounted. A sketch of the kiln setup is shown in Figure 2. 

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