Liquid isothermal bath

The liquid isothermal bath (LIB) was first applied in producing PET fibers by NCSU researchers in early 1990s. The initial motivation was quite straightforward, i.e., to produce high tenacity/ high modulus fibers via a one-step high-speed spinning process. 

Figure 9.24 Schematic of traditional melt spin-draw process and liquid isothermal bath (LIB) process.

The adsorption isotherm up to 200 mm. Hg was completed and afterwards the sample was evacuated. Evacuation was started at —183° and continued for 40 minutes at that temperature. Thereafter the temperature was increased to —78° and evacuation continued at that temperature for thirty minutes. The sample was cooled down in He and evacuated. A second CO isotherm was taken at —183°. The difference between the two isotherms was determined to be 2.7 % of a monolayer. To insure that this sample had not, in some way or other, been oxidized, the temperature was raised to —78° with the sample still kept in the CO atmosphere. The sample was kept at — 78° for a few minutes only and the dry-ice bath again substituted by the liquid oxygen bath. During the temperature cycle more CO had been adsorbed so that the amount of chemisorption was now equal to 10.6% of a monolayer, 7.9% having been taken up during the temperature cycle. 

Nitrogen Sorption. The outgassed sample was cooled to 77 K by a stirred liquid nitrogen bath maintained at a constant level (6, 7). Nitrogen vapor was introduced and controlled at a constant pressure until the steady state conditions shown in Figure 1 prevailed. Maintaining fixed temperature and pressure on selected intermediate pressures for both adsorption and desorption assured us that there were no slow processes in play detectable in the 2-3-day periods used. The disparity between desorption and adsorption isotherms can be attributed confi-... 

As noted above, the mass transfer kinetics of temperature gradient loops are usually described with reference to dissolution in the hot leg. It is possible to quantitatively study the dissolution step using the rotating cylinder technique. Unlike loop studies, this technique allows one to study dissolution in a system where the hydrodynamic conditions are fully defined. Experimentally, solid cylinders of the test material are rotated at various speeds in an isothermal liquid-metal bath. Changes in the concentration of solid in the liquid and changes in the cylinder radius are determined as a function of time. With these data it is possible to determine the mass transfer coefficient and the rate-controlling step for dissolution. 

With the system at a steady-state temperature (T at approximately IK), the working salt is brought into thermal contact with the liquid helium bath by opening the upper thermal valve and closing the lower thermal valve. As the magnetic field is applied for process step 1-2, the entropy of the salt is decreased isothermally. 

Ammonia (aqueous) [7664-41-7] M 17.0 + H2O, d 0.90 (satd, 27% w/v, 14.3 N), pK 9.25. Obtained metal-free by saturating distilled water, in a cooling bath, with ammonia (from tank) gas. Alternatively, can use isothermal distn by placing a dish of cone aq ammonia and a dish of pure water in an empty desiccator and leaving for several days. AMMONIA (gas, liquid or aq soln) is very irritating and should not be inhaled in large volumes as it can lead to olfactory paralysis (temporary and partially permanent). 

A liquid flow microcalorimeter, the thermal activity monitor (TAM), is commercially available from ThermoMetric (formerly LKB/Bofors). This instrument consists of two glass or steel ampules with a volume of 3 to 4 cm3 (25 cm3 ampule available with a single detector), placed in a heat sink block. Recently, an injection-titration sample vessel was developed which acts as a microreactor. This vessel is provided with flow-in, flow-out, and titration lines, with a stirring device. The isothermal temperature around the heat sink is maintained by a controlled water bath. Each vessel holder, containing an ampoule, is in direct contact with a thermopile array, and the two arrays are joined in series so that their output voltages subtract. The two pairs of thermopile arrays are oppositely connected to obtain a differential output,... 

Methods. Adsorption isotherms were run at constant feed molar ratio of C oS0 /Ci3eS0.. The feed solutions had a pH of 4.25 and a NaCl concentration of 0.15 M. Ten ml of feed solution was added to 0.5 g alumina in a screw top centrifuge tube and centrifuged at 700 RPM for 45 minutes at room temperature. The tube was then placed in a water bath at 30°C for four days, the liquid decanted from the mineral and analyzed. The surfactant concentrations were analyzed using high performance liquid chromatography with a conductivity detector. The solution pH after equilibration was determined using pH electrodes. The equilibrium pH increased to 6.8 at equilibrium because the PZC of alumina is approximately 9. 

A liquid gold-copper alloy contains 45mol% of copper and behaves ideally at 1,320K. Calculate the amount of heat absorbed in the system when Ig of solid copper is dissolved isothermally at this temperature in a large bath of the alloy of this composition. The following dam given ... 

Liquid nitrogen is the most convenient constant-temperature bath for isotherm measurements with N2 gas. For high-precision work, the temperature of this bath should be measured with a thermocouple so that an accurate value of po can be obtained, or po should be measured directly with a separate nitrogen vapor-pressure manometer. For this experiment it is adequate to assume that po is equal to the atmospheric pressure in the room. 

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