Thermal-conductivity analyzer

Thermal-Conductivity Analyzer. The thermal-conductivity analy2er operates on the principle that the loss of heat from a hot wire by gaseous conduction to a surface at a lower temperature varies with the thermal conductivity of the gas, and is virtually independent of pressure between 1.3 kPa (10 mm Hg) and 101 kPa (1 atm). This technique is frequently used in continuous monitors for tritium in binary gas mixtures for immediate detection of process change. 

The principal object of experimental runs was to determine the overall plate efficiency. Sample taps, located at seven points along the column (Fig. 1), fed gas phase samples to a continuously recording thermal conductivity analyzer [10]. These analyses were recorded along with the other process variables so that the overall plate efficiency could be determined as a function of vapor velocity. This dependence is shown in Fig. 2. 

Liquid oxygen analyses are customarily made for process control, product purity and to avoid hazards. Usually analytical information required for process control is not extensive. Use of modified Or sat apparatus for manual determination of the oxygen contents of various liquid samples is routine in most plants. Relatively simple thermal conductivity analyzer-controllers govern the flow of liquid air fractions under distillation where differential pressure control is not applicable. Pressure drop and inspection of liquid in a small glass flask are usually sufficient for mechanical filter cycle regulation but a continuous carbon dioxide analysis may be helpful as a check on the overall function. A method which is sufficiently precise for this use is discussed later. 

The through-plane thermal conductivity (TC) of a 3.2-mm thick, 5.1-cm diameter disc-shaped test specimen was measmed at 801C using a Holometrix Model TCA-300 Thermal Conductivity Analyzer, which uses ASTM F433... 

Ozone can be analyzed by titrimetry, direct and colorimetric spectrometry, amperometry, oxidation—reduction potential (ORP), chemiluminescence, calorimetry, thermal conductivity, and isothermal pressure change on decomposition. The last three methods ate not frequently employed. Proper measurement of ozone in water requites an awareness of its reactivity, instabiUty, volatility, and the potential effect of interfering substances. To eliminate interferences, ozone sometimes is sparged out of solution by using an inert gas for analysis in the gas phase or on reabsorption in a clean solution. Historically, the most common analytical procedure has been the iodometric method in which gaseous ozone is absorbed by aqueous KI. 

Applied Sciences, Inc. has, in the past few years, used the fixed catalyst fiber to fabricate and analyze VGCF-reinforced composites which could be candidate materials for thermal management substrates in high density, high power electronic devices and space power system radiator fins and high performance applications such as plasma facing components in experimental nuclear fusion reactors. These composites include carbon/carbon (CC) composites, polymer matrix composites, and metal matrix composites (MMC). Measurements have been made of thermal conductivity, coefficient of thermal expansion (CTE), tensile strength, and tensile modulus. Representative results are described below. 

Catalytic activity for the selective oxidation of H2S was tested by a continuous flow reaction in a fixed-bed quartz tube reactor with 0.5 inch inside diameter. Gaseous H2S, O2, H2, CO, CO2 and N2 were used without further purification. Water vapor (H2O) was introduced by passing N2 through a saturator. Reaction test was conducted at a pressure of 101 kPa and in the temperature range of 150 to 300 °C on a 0.6 gram catalyst sample. Gas flow rates were controlled by a mass flow controller (Brooks, 5850 TR) and the gas compositions were analyzed by an on-line gas chromotograph equipped with a chromosil 310 coliunn and a thermal conductivity detector. 

TEM observation and elemental analysis of the catalysts were performed by means of a transmission electron microscope (JEOL, JEM-201 OF) with energy dispersion spectrometer (EDS). The surface property of catalysts was analyzed by an X-ray photoelectron spectrometer (JEOL, JPS-90SX) using an A1 Ka radiation (1486.6 eV, 120 W). Carbon Is peak at binding energy of 284.6 eV due to adventitious carbon was used as an internal reference. Temperature programmed oxidation (TPO) with 5 vol.% 02/He was also performed on the catalyst after reaction, and the consumption of O2 was detected by thermal conductivity detector. The temperature was ramped at 10 K min to 1273 K. 

The catalytic reforming of CH4 by CO2 was carried out in a conventional fixed bed reactor system. Flow rates of reactants were controlled by mass flow controllers [Bronkhorst HI-TEC Co.]. The reactor, with an inner diameter of 0.007 m, was heated in an electric furnace. The reaction temperatoe was controlled by a PID temperature controller and was monitored by a separated thermocouple placed in the catalyst bed. The effluent gases were analyzed by an online GC [Hewlett Packard Co., HP-6890 Series II] equipped with a thermal conductivity detector (TCD) and carbosphere column (0.0032 m O.D. and 2.5 m length, 80/100 meshes), and identified by a GC/MS [Hewlett Packard Co., 5890/5971] equipped with an HP-1 capillary column (0.0002 m O.D. and 50 m length). 

The activity tests of the catalyst were carried out in a microflow reactor set-up in which all the high temperature parts are constructed of hastelloy-C and monel. The reactor effluent was analyzed by an on-line gas chromatograph with an Ultimetal Q column (75 m x 0.53 mm), a flame ionization detector, and a thermal conductivity detector. The composition of the feed to the reactor can be varied, besides the temperature, pressure, and space velocity. The influence of the recycle components CHCIF2 and methane was tested by adding these components to the feed. In total five stability experiments of over 1600 hours were performed. In each... 

The product gases were continuously analyzed for NO and NO2 using a chemiluminescent analyzer, and discontinuously for N2O, N2, CO, CO2 and O2 by GC equipped with a thermal conductivity detector and an electron capture detector, specifically for the N2O analysis, using a Poraplot Q column and a molsieve 5A column for separation. 

Ozonolysis. Ozonolysis of the methylhexadiene polymer was conducted (21)at room temperature on a solution of 1,03 g. polymer in 20 ml. tetrahydrofuran with the aid of the Wellsbach ozonizer. The end point for the ozonolysis was observed after about 15 min. by the reaction of excess ozone with starch-iodide solution. Triphenylphosphine was added to the reaction mixture and allowed to react at room temperature for 60 hr. The resulting product was analyzed by GLC (Hewlett Packard 5750, Porapak Q 10 ft. x 1/8 in. column at 110°C, helium pressure 60 psi, thermal conductivity detector at 190°C, injector 200°c). 

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