Enthalpy, plot

Some representative plots of entropies of adsorption are shown in Fig. XVII-23, in general, T AS2 is comparable to Ah2, so that the entropy contribution to the free energy of adsorption is important. Notice in Figs. XVII-23 i and b how nearly the entropy plot is a mirror image of the enthalpy plot. As a consequence, the maxima and minima in the separate plots tend to cancel to give a smoothly varying free energy plot, that is, adsorption isotherm. 

Fig. 6. Temperature—relative enthalpy plots showing network parameters of minimum utiUty for (a) the case requiring infinite area (b) where heat balance...

Figure 2, the pressure-enthalpy plot of the standard vapor compression cycle, traces the state of the refrigerant through the refrigeration system. (Enthalpy represents the energy of the refrigerant as... 

A quick glance at Fig. 5 illustrates the fallacy of this appraoch. Both 12 and phenol cannot give linear, enthalpy plots with SbCls unless they give linear plots with each other. The apparent success in... 

The most convenient method for representation of enthalpy data for binary J solutions is by enthalpy/ concentration (Hx) diagrams. These diagrams are graphs T of the enthalpy plotted as a function of composition (mole fraction or mass fraction of one species) with temperature as parameter. The pressure is a constants and is usually 1 atmosphere. Figure 13.10 shows a partial diagram for the H2SO4/H2O system. 

The absolute aulsorption isotherms for —30°C and TO C were calculated from the 20°C isotherm using the integrated form of Eq. (1) and the differential enthalpy plotted on Fig. 2. The reasonable approximation was made that the differentiaJ enthaJpy is independent of temperature. No other assumptions were needed to calculate the excess adsorption isotherms on Fig. 3. 

Enthalpy-relaxation data obtained for glassy PC and PET during isothermal anneadlng at several temperatures belov their respective T s are given in Figures 2 and 3, In vhich the excess enthalpy plotted as a function of log t. The calculations or, T., r) vere based on (c - c ) of 0.0778... 

Fig. 38. A proposed enthalpy plot as a function of reaction coordinate for CO adsorption and dissociation on Rh. From Bowker (1992).

If a liqnid is released while its temperatnre is above the atmospheric-pressnre boiling point, some of the liqnid will adiabatically and instantaneously flash to vapor that is, the energy that is released as the liqnid temperatnre drops to the boiling point is ntihzed in vaporizing some of the liqnid. The fraction of liqnid that is flash-vaporized often can be obtained from a thermodynamic diagram (snch as a pressnre-enthalpy plot [8, 13]) for the material of interest, where values of x (if shown) indicate the weight-fractions of vapor ( quality ) in the two-phase mixture. 

Figure 3.10 shows the heat integration for the base case in a conventional temperature-enthalpy plot used for pinch analysis. 

Solution enthalpies are typically presented graphically in the form of excess enthalpies plotted as a function of composition and temperature, such as those in Figure 12-3. From such data we can obtain the enthalpy of solution by adding the excess enthalpy to the ideal-solution enthalpy ... 

Figure A4 shows the enthalpy-temperature diagram for carbon dioxide. Plotting in this manner is a little imconventional. It is more common to make pressure-enthalpy plots. One look at Figure A4 and you can see why - it is very complicated.

Fifteen percent of the air compressed from 0.101 MPa to 20.2 MPa in a Lindle precooled liquefier is liquefied. With the aid of a temperature-entropy diagram calculate values of rhhhh, the enthalpy of the high-pressure stream, and rh h, the enthalpy of the low-presure stream. Take the cold end of the exchanger just above the expansion valve as the reference zero for the changes in enthalpy. Plot values ol rh Ah and rhc Ah versus the temperature. Does the temperature at which the A T becomes zero agree with the temperature to which the air must be precooled to achieve 15% liquefaction ... 

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