Temperature equilibria

An excessively high temperature may diminish the chance of detecting some structural characteristics that can be obtained only from the study of the dimers, trimers, tetramers, etc. of the polymer. If only the monomer and small molecules are generated during pyrolysis, information on properties such as stereospecificity or copolymeric structure is lost. For this reason, Tgq values around 600° C may be more appropriate for certain studies using analytical pyrolysis. 

The variability in analytical pyrolysis results as a function of equilibrium temperature Tqq in the pyrolysis of a polymer is further exemplified for poly(diallyl isophthalate), which has the idealized structure shown below  

Other examples showing the influence of pyrolysis temperature on pyrolysis results are shown later in this book (see e.g. Section 13.4). 

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Note that in this nonnalized probability, the properties of the reser >oir enter the result only through the common equilibrium temperature T. The accuracy of the expansion used above can be checked by considering the next temi, which is... 

The basic features of folding can be understood in tenns of two fundamental equilibrium temperatures that detennine tire phases of tire system [7]. At sufficiently high temperatures (JcT greater tlian all tire attractive interactions) tire shape of tire polypeptide chain can be described as a random coil and hence its behaviour is tire same as a self-avoiding walk. As tire temperature is lowered one expects a transition at7 = Tq to a compact phase. This transition is very much in tire spirit of tire collapse transition familiar in tire theory of homopolymers [10]. The number of compact... 

The oxygen is turned on, tap Tj carefully opened and the furnace N and the thermostatic mortar P then turned on. The apparatus can conveniently be allowed to attain its equilibrium temperature over the period of about 20 minutes while the absorption tubes are being polished and weighed and the specimen for andysis weighed out it is thus ready for immediate use as soon as the weighings have been completed. 

To understand the conditions which control sublimation, it is necessary to study the solid - liquid - vapour equilibria. In Fig. 1,19, 1 (compare Fig. 1,10, 1) the curve T IF is the vapour pressure curve of the liquid (i.e., it represents the conditions of equilibrium, temperature and pressure, for a system of liquid and vapour), and TS is the vapour pressure curve of the solid (i.e., the conditions under which the vapour and solid are in equili-hrium). The two curves intersect at T at this point, known as the triple point, solid, liquid and vapour coexist. The curve TV represents the... 

To reach equilibrium temperature quickly before starting the equilibration phase of a simulation (see Equilibration and Data Collection on page 74). 

For 1 = 6 the contribution of AH° is unfavorable and that of AS° is favorable. The specific values make T = 298 K very close to the equilibrium temperature. This implies that the reaction is shifted to favor polymer at higher temperatures and to favor the cyclic monomer at lower temperatures. Since the difference between AH° and T AS° is so small, the temperature dependence of AH° and AS° could alter this conclusion. 

Wet-bulb temperature is the dynamic equilibrium temperature attained by a water surface when the rate of heat transfer to the surface by convection equals the rate of mass transfer away from the surface. At equilibrium, if neghgible change in the dry-bulb temperature is assumed, a heat balance on the surface is... 

In order to cool to the equilibrium temperature, a pond of infinite size would be required for warm water. An approach of 1.7 to 2.2°C (3 to 4°F) is the lowest practicable in a pond of reasonable size. For a pond having more than a 24-h holdup, the leaving-water temperature will vary from the average by plus or minus 1.1°C (2°F) for a 0.9-m (5-ft) depth and 1.7°C (3°F) variation for a 0.9-m (3-ft) depth. 

AH = latent heat of transformation = equilibrium temperature (absolute). 

TABLE 5-1.4.1 Approximate Vapor-Liquid Equilibrium Temperatures for LFL, LMIE, and UFL Vapor Concentrations at Atmospheric Pressure... 

Any saturated vapor can be condensed by a direct spray of cold water under correct temperature and pressure. If sufficient contact is provided, coolant and vapor will reach an equilibrium temperature. The condensate created by the water should not be objectionable in its liquid form. 

Tg = equilibrium temperature corresponding to the vapor pressure where the vapor pressure is the relief device set pressure (K)... 

When a damp cloth is laid in an air flow, it settles after a certain time ic an equilibrium temperature, the so-called wet bulb temperature (0 ), which is determined through heat and mass transfer. Negotiating the heat flow obtained by radiation and conduction, the heat balance of the wet cloth in a stationary situation can be expressed as... 

If, instead, the air is damped adiabatically with the wet cloth, so that the state of the air varies, the cloth will settle to a slightly different temperature. Each state of air (0, x) is represented by a certain wet bulb temperature 6, which can be calculated from Eq. (4.116) or its approximation (4.123), when the partial pressures of water vapor are low compared with the total pressure. When the state of air reaches the saturation curve, we have an interesting special case. Now the temperatures of the airflow and the cloth are identical. This equilibrium temperature is called the adiabatic cooling border or the thermodynamic wet bulb temperature (6 ). 

Another technique that can be used to account for the presence of liquids is to assume that the water and oil in the stream pass through the choke with no phase change or loss of temperature. The gas is assumed to cool to a temperature given in Figure 4-8. The heat capacity of the liquids is then used to heat the gas to determine a new equilibrium temperature. 

The polarity of the C—-OH bond, i.e., the basicity of the carbinol-amine, depends on its structure, particularly on the stability of the ring system (degree of aromatic character), and the electron affinity of the substituents on nitrogen and carbon. Of course, external factors also play an important role in the equilibrium temperature, polarity of the solvent, and presence or absence of catalysts (the solvent can also act as a catalyst). 

It should be noted that studying states of order in thermal equilibrium as a function of temperature yields the possibility of measuring the degree of order of a system in values of corresponding equilibrium temperature . This way, the results of residual resistometry are independent of the detailed formalism between state of order and electrical resistivity... 

Tst = equilibrium temperature at which exists over liquid in dry air at a temperature, °C or °F per chart. 

Tl = equilibrium temperature at which the lower flammable limit composition exists over liquid in dry air at one atmosphere (theoretical flash point), °C or °F Ty = equilibrium temperature at which the upper flammable limit composition exists over liquid in dry air at one atmosphere, °C or °F... 

Operating Conditions Feed gas enters at equilibrium temperature at bottom of tower... 

Make-up water enters at equilibrium temperature at top of tower Vent contains 0.1 wt.% HCl... 

The weak aqua leaving the heat exchanger ahead of the absorbers is assumed to be cooled to about 6-11°F (sometimes more) less than this equilibrium temperature of 138°F. Then the weak liquid entering the absorbers is taken as 138°F - 10°F = 128°F. This may have to be corrected later if proper balance is not reached. Figure 11-17A is also a useful reference. 

Mix Zone Temperature is the theoretical equilibrium temperature between the regenerated catalyst and the uncracked vaporized feed at the bottom of I he riser. 

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