Critical condensation temperature

Trouton s rule phys chem An approximation rule for the derivation of molar heats of vaporization of normal liquids at their boiling points. traCit anz. riil ) true condensing point See critical condensation temperature. trii kan dens ir). point) true electrolyte puys chem A substance in the solid state that consists entirely of ions. trir i lek-tr9,lTt)... 

Hong et al. (2001) argue that their results are associated with competition between two effects (1) a difference in critical condensation temperature between mixture constituents and (2) the dynamic sieving effect associated with the space filling of small particles beneath larger ones. The analogous results derived by Jenkins and Yoon (2002) were obtained for systems that satisfy certain... 

Example 15.4 A reboiler is required to supply 0.1 krnol-s 1 of vapor to a distillation column. The column bottom product is almost pure butane. The column operates with a pressure at the bottom of the column of 19.25 bar. At this pressure, the butane vaporizes at a temperature of 112°C. The vaporization can be assumed to be essentially isothermal and is to be carried out using steam with a condensing temperature of 140°C. The heat of vaporization for butane is 233,000 Jkg, its critical pressure 38 bar, critical temperature 425.2 K and molar mass 58 kg krnol Steel tubes with 30 mm outside diameter, 2 mm wall thickness and length 3.95 m are to be used. The thermal conductivity of the tube wall can be taken to be 45 W-m 1-K 1. The film coefficient (including fouling) for the condensing steam can be assumed to be 5700 W m 2-K 1. Estimate the heat transfer area for... 

If the normal boiling point of the overhead composition is below the coldest cold utility, then the minimum condenser temperature in a column will be equal to the temperature of the coldest cold utility plus ATroi . They take the values of 341.92,343.01,353.54 and 341.92 for tasks 1,2,3 and 4 respectively. The maximum reboiler temperature, if critical conditions are not approached by the hottest hot utility, will be the temperature of the hottest hot utility minus ATm n- Based on the data, the maximum reboiler temperature is 411 K. 

Critical point Temperature and pressure above which a substance cannot condense into a liquid. 

Condenser temperatures at three to six critical points near the water vapor entry, at the innermost and outermost coil or plate, and at the level of the pipe to the VPS, recorded (dte)... 

Typical results are shown in Fig. 6 for U-methane in graphite pores of H =7.5 at T=114 K. At p/ps=l the system is solid-like at this temperature, but a discrete change in density occurs around p ps ca.0.5. The self diffiisivity along axial direction also shows drastic change at this point. Further examination of various characteristics of molecular state such as snapshots, in-plane pair correlations and static structure factors confirmed that this change in density is the result of a phase transition from solid-like state to liquid-like one, or melting. Since the critical condensation condition for this pore is far lower than this transition point to stay around p ps= ca.0.2, the liquid-like state is not on metastable branch but thermodynamically stable. Thus a solid-liquid coexistence point is found for this temperature. 

The experiments under examination are carried out at temperatures higher than the critical ethylene temperature. The observed effects cannot possibly result from any ethylene liquefaction (capillary condensation) within the solid pores. 

At the point C the two liquid layers become identical, and this is called the critical solution point or con-solute point. If the total applied pressure is varied, both the critical temperature and composition of the critical mixture alter and we obtain a critical solution line. As an example of this we give in table 16. If the dependence of the critical solution temperature on pressure for the system cyclohexane -f aniline. An increase of pressure raises the critical solution temperature, and the mutual solubility of the two substances is decreased. We saw earlier that the applied pressure had only a small effect on the thermodynamic properties of condensed phases, and we notice in this case that an increase of pressure of 250 atm. alters the critical temperature by only 1.6 °C. 

The amount of physical adsorption decreases rapidly as the temperature is raised and is generally very small above the critical temperatures of the adsorbed component. This is further evidence that physical adsorption is not responsible for catalysis. For example, the rate of oxidation of sulfur dioxide on a platinum catalyst becomes appreciable only above 300°C yet this is considerably above the critical temperature of sulfur dioxide (157°C) or of oxygen ( — 119°C). Physical adsorption is not highly dependent on the irregularities in the nature of the surface, but is usually directly proportional to the amount of surface. However, the extent of adsorption is not limited to a monomolecular layer on the solid surface, especially near the condensation temperature. As the layers of molecules build up on the solid surface, the process becomes progressively more like one of condensation. 

The critical temperatures of ethylene and ethane are 49 and 90"F, respectively, at critical pressures of 730 and 708 psia, respectively. The critical point for 99 mol% ethylene is approximately at SOT and 729 psia. Therefore, it is not possible to use cooling water in the condenser because it can only achieve a condensing temperature of 100"F. ... 

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