Sliding-temperature path

Polythermal reactions paths are those in which temperature varies as a function of reaction progress, . In the simplest case, the modeler prescribes the temperatures T0 and Tf at the beginning and end of the reaction path. The model then varies temperature linearly with reaction progress. This type of model is sometimes called a sliding temperature path. 

The calculation procedure for a sliding temperature path is straightforward. In taking a reaction step, the model evaluates the temperature to be attained at the step s end. Since varies from zero to one, temperature at any point in reaction progress is given by,... 

In an example of a sliding temperature path, we consider the effects of cooling from 300 °C to 25 °C a system in which a 1 molal NaCl solution is in equilibrium with the feldspars albite (NaAlSiaOs) and microcline (KAlSisOg), quartz (SiC>2), and muscovite [KAl3Si30io(OH)2]. To set up the calculation, we enter the commands... 

A second type of polythermal path traces temperature as reactants mix into the equilibrium system. This case differs from a sliding temperature path only in the manner in which temperature is determined. The modeler assigns a temperature To to the initial system, as before, and a distinct temperature Tr to the reactants. By assuming that the heat capacities CP, CPk, and CPr of the fluid, minerals, and reactants are constant over the temperature range of interest, we can calculate temperature (< ) from energy balance and the temperature T(c ) at the onset of the step according to... 

Fig. 2.10. Use of the dump option to simulate scaling. The pore fluid is initially in equilibrium with minerals in the formation. As the fluid enters the wellbore, the minerals are isolated (dumped) from the system. The fluid then follows a polythermal, sliding-fugacity path as it ascends the wellbore toward lower temperatures and pressures, depositing scale.

The silsesquioxane mixtures or the separated silsesquioxanes can be analyzed by MALDl-TOF-MS (Table 2). MALDI-TOF mass spectrometry was carried out on a Kratos Kompact MALDI 111. 0.5 pL of a solution (25 mg/mL) of 2,4,6-trihydroxyacetophenone or 20 mg/mL of 2-nitrophenyl octyl ether and 10 mg/mL silver trifluoroacetate were mixed on a stainless steel sample slide. The solvent was evaporated in a stream of air at ambient temperature. Bovine insulin was used for calibration. Conditions for the measurements polarity positive, flight path reflection, 20 kV acceleration voltage, nitrogen laser (A = 337 nm). 

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