Desired temperature

Fluid Coking", developed in 1953. The reaction proceeds at atmospheric pressure, at about SOO-SSOT, in a reactor whose feed is mixed in a fluidized bed of hot coke which maintains the desired temperature. 

An interesting experimental technique is heat development of nuclei. The liquid is held at the desired temperature for a prescribed time, while nuclei accumulate they are then made visible as crystallites by quickly warming the solution to a temperature just below Tq, where no new nuclei form but existing ones grow rapidly. 

In a molecular dynamics calculation, you can add a term to adjust the velocities, keeping the molecular system near a desired temperature. During a constant temperature simulation, velocities are scaled at each time step. This couples the system to a simulated heat bath at Tq, with a temperature relaxation time of "r. The velocities arc scaled bv a factor X. where... 

An alternative way to maintain the temperature is to couple the system to an external he bath that is fixed at the desired temperature [Berendsen et al. 1984]. The bath acts as a sopr of thermal energy, supplying or removing heat from the system as appropriate. T1 velocities are scaled at each step, such that the rate of change of temperature is proportion to the difference in temperature between the bath and the system ... 

Despite the apparent ease of determining an analyte s concentration using the Nernst equation, several problems make this approach impractical. One problem is that standard-state potentials are temperature-dependent, and most values listed in reference tables are for a temperature of 25 °C. This difficulty can be overcome by maintaining the electrochemical cell at a temperature of 25 °C or by measuring the standard-state potential at the desired temperature. 

If solvent recovery is maximized by minimizing the temperature approach, the overall heat-transfer coefficient in the condenser will be reduced. This is due to the fact that a large fraction of the heat transfer area is now utilized for cooling a gas rather than condensing a Hquid. Depending on the desired temperature approach the overall heat-transfer coefficients in vent condensers usually range between 85 and 170 W/m K (ca 15 and 30 Btu/h-ft. °F). 

These furnaces may operate batchwise or continuous. In the batch, intermittent, or periodic types, the content is heated at the desired temperature for the stipulated time and then removed. In the continuous type, the charge moves at a predeterrnined rate through one or more heating 2ones to emerge in most cases at the end opposite the point of entry. Figures 9 and 10 are representative examples of typical, industrial refractory-wall furnaces. 

In a commercial unit, a spray nitrator (39) is operated adiabaticaHy. The Hquid HNO feed is sprayed direcdy into the hot and preheated propane feed. The heat of nitration provides the heat to vaporize the HNO and to preheat it to the desired temperature for nitration. At one time, several spray nitrators were operated in series, with additional HNO being sprayed into each nitrator (32). In such an arrangement, the optimum propane HN02 ratios did not occur, and considerable amounts of nitroparaffins degraded. 

High temperature strength of refractory materials is determined on rectangular prisms 25 x 25 x 150 mm cut from the product being tested. The specimens are placed ia a furnace, heated to a desired temperature, and the modulus of mpture is determined. A detailed description is given ia ASTM C583. 

Because of its low and regular thermal expansion, vitreous sHica is employed ia apparatus used to measure the thermal expansion of soHds. A detaHed account of the different methods used for this purpose has been pubHshed (227). The most common form of dHatometer utilizes a vitreous sHica tube closed at the bottom and containing the test sample. A movable rod of vitreous sHica, resting on the sample, actuates a dial iadicator resting on the top of the rod. The assembly containing the sample is placed ia a furnace, bath, or cooling chamber to attain the desired temperature. 

In austempering the article is quenched to the desired temperature in the lower bainite region, usually in molten salt, and kept at this temperature until transformation is complete (Fig. 22). Usually, the piece is held twice as long as the period indicated by the isothermal transformation diagram. The article may then be quenched or air-cooled to room temperature after transformation is complete, and may be tempered to lower hardness if desired. 

Ceramic-matrix composites are a class of materials designed for stmctural applications at elevated temperature. The response of the composites to the environment is an extremely important issue. The desired temperature range of use for many of these composites is 0.6 to 0.8 of their processing temperature. Exposure at these temperatures will be for many thousands of hours. Therefore, the composite microstmcture must be stable to both temperature and environment. Relatively few studies have been conducted on the high temperature mechanical properties and thermal and chemical stability of ceramic composite materials. 

---