Linear heat rating

Figure 4.46. Thermal desorption spectra after electrochemical O2 supply to Ag/YSZ through the electrolyte for 10 min. Each curve corresponds to different adsorption temperature and current in order to achieve nearly constant initial coverage. Desorption was performed with linear heating rate, p=l K/s (Inset) Effect of potential on peak temperature.31 Reprinted with permission from Academic Press.

Figure 5.21. Experimental setup (inset) showing the location of the working (WE), counter (CE) and reference (RE) electrodes and of the heating element (HE) thermal desorption spectra after gaseous oxygen dosing at 673 K and an 02 pressure of 4x1 O 6 Torr on Pt deposited on YSZ for various exposure times. Oxygen exposure is expressed in kilo-langmuirs (1 kL=l0 3 Torrs). Desorption was performed with linear heating rate, ()=1 K/s.4 S Reprinted with permission from Academic Press.

Measurement of Volatile Matter Release Rates. Volatile matter release rates from anthracite were determined by using the apparatus shown diagram-matically in Figure 1. The power input to the 1-kw., 20-volt Hoskins tube furnace and transformer was controlled by means of a Leeds Northrup durationadjusting type program controller which permitted linear heating rates up to 20°C. per min. to be selected with varying soak times and temperatures. A maximum temperature of 1000°C. was used since this was the maximum temperature at which the furnace could be operated continuously. The temperature of the furnace was measured by a chromel-alumel thermocouple inside a... 

Although the use of linear heating rates introduces considerable complexity into the mathematics, it is of interest to note that the slope of the curve (above the critical temperature) shown in Figure 3 can be related to desorption theory. By differentiating Equation 1 with respect to time, it follows that... 

Temperature programmed desorption (TPD) of NH3 was performed in a quartz micro-reactor. 0.10 g of sample was firstly heated in helium at 600°C for 2 h. NH3 was introduced to the sample after it was cooled down to room temperature. To remove the weakly adsorbed NH3, the sample was swept using helium at 100°C for 1 h. The TPD experiments were then carried out with a carrier-gas flow rate of 40 ml/min helium from 100 to 600°C using a linear heating rate of 10°C/min. The desorption of NH3 was detected by Shimadzu GC-8A equipped with a TCD detector. 

Severe emergency core cooling system criteria require that the builders of water reactors increase the linear feet of fuel in the reactor core for the same power in order to reduce LOCA (loss-of-cooling accident) fuel temperatures. In the unit described here, an assembly with a 16 x 16 fuel rod array of smaller diameter rods is used in the same assembly envelope that was occupied by a 14 x 14 assembly in earlier designs. This results in a maximum linear heat rate decrease in the assembly of about 25%. 

DTA measurements in the temperature range between 20 and 600°C were carried out after sulfidation by means of a PAULIK derivatograph type OD-103. All experiments run in dry air at a linear heating rate of 10°C/min. Sulfur analysis was carried out in a combustion equipment. 

A chrome -alumel thermocouple was set in close proximity to the sample inside a reactor. The reactor was made of a quartz tube which was surrounded by a tubular furnace. In a typical coal pyrolysis run, the coal sample (20-30 mg) was placed in a platinum boat which was suspended from the quartz beam of the TGA balance. The coal particle size used was 100-200 mesh. Samples were heated to desired temperatures at linear heating rates or heated iso-thermally under various gaseous environments. 

The DSC data were obtained with a Du Pont cell base and a Model 990 thermal analyzer. An aluminum pan containing the sample was placed on the raised platform in the DSC cell, and an empty pan was placed on the reference platform. DSC scans for the samples were obtained from 150° to 600°C at a linear heating rate of 20°C/min. During the run, a slight flow of nitrogen was maintained. The TGA data was taken with a Du Pont 951 TGA balance in conjunction with a Model 990 thermal analyzer. A platinum boat containing the sample was suspended from the quartz beam of the balance. Samples were heated to 900°C at 20°C/min with a constant nitrogen flow. 

More complex thermal lag effects Not as precise linear heating rate Many experimental parameters... 

Compared with mixed oxide fuels, the mixed carbide fuels have higher heavy metal density (13 vs. 9.7 g/cm ), better neutron economics, greater thermal conductivity (10 times greater), higher linear heat rate capability [1485 W/cm (45 kW/ft) for carbide]... 

The rates of oil, hydrogen, methane, carbon dioxide and carbon monoxide evolution during the retorting of five Australian oil shales at linear heating rates have been determined and analysed in terms of the Anthony-Howard model for non-iso-thermal kinetics. Significant differences in the retorting properties of these shales were obtained, particularly with respect to the rates of the hydrogen and carbon dioxide evolution. 

The XPS measurements were carried out on a VG ESCALAB Mark II electron spectrometer. TPD data was also collected on the same system using VG SX 200 Mass spectrometer. The Ru(OOl) crystal was fixed on a liquid N2 cooled manipulator and its temperature was measured by chromel/alumel thermocouple spot-welded on the side. The crystal temperature could be varied from 95 to 1500 K. The crystal surface was cleaned initially by Ar-ion bombardment and then annealed at 1200 K for about 20 min before flashing to 1500 K. The Sm was deposited by resistive heating of Sm sample inside the preparation chamber. CO doses to the crystal surface were measured in Langmuir units (1L=10 Torr-sec). A linear heating rate of 5 K/sec was applied for TPD measurements. 

The supported catalysts were characterized for their basicity distribution by temperature programmed desorption (TPD) of CO2 from 50 to 950 C at a linear heating rate of 20°C.min in a flow of helium(40cm. min ). The surface area of the catalysts was determined by the single-point BET method, using a Monosorb surface-area analyser (Quanta Chrome Corp. USA). 

Raw shale contained in the top furnace and reactor was retorted at a linear heating rate. Gases and vapors evolved during retorting passed through the second reactor at 504 to 610°C where the oil was thermally cracked. Temperatures were measured at the center of the bottom reactor by a stainless-steel-sheathed thermocouple (Type K). Temperature variation across the reactor was less than 3°C. To simulate conditions inside a shale block, the bottom reactor contained pieces of shale. We used burnt shale (mostly silicates and MgO) in most of the experiments because it is thermally stable above 500°C. In two experiments, we used retorted shale (2.7% organic carbon, 24.4% acid-evolved CO2) and no shale, respectively. 

A DTA apparatus that could be used up to a pressure of 4000 bar and temperatures to 500°C was described by Kuballa and Schneider (75). This apparatus, which is illustrated in Figure 6.22, contained a DTA cell that was constructed of stainless steel a maximum pressure of 4000 bar and a maximum temperature of 500CC were possible. The cell was enclosed by two Bridgman pistons which contained the thermocouples. Cell wells for the sample and reference materials were made from a 97% platinum-3% iridium alloy they were suspended on the sheathed thermocouple junctions. Upper and lower sides of the sample-holder area were thermally heated by Zr02 blocks. A furnace placed around the pressure vessel permitted linear heating rates from 0.2 to 10°C/min. 

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