Enthalpy diagram

Let us consider the formation of sodium chloride from its elements. An energy (enthalpy) diagram (called a Born-Haber cycle) for the reaction of sodium and chlorine is given in Figure 3.7. (As in the energy diagram for the formation of hydrogen chloride, an upward arrow represents an endothermic process and a downward arrow an exothermic process.)... 

Figure 5-4 Enthalpy Diagram for Hydrogenation of Ethylene. The values were...

Remarkably accurate experimental results have been obtained, also by Kistia-kowsky (Conant and Kistiakowsky, 1937), which permit indirect calculation of the enthalpy change of this isomerization AThe enthalpy diagram for isomcn/atioii of 2-butciic is given in Fig. 5-.5. We shall use TINKER and PCMODEL U) (ind the length of each arrow in Fig. 5-5. We shall also use the PCMODEL GUI. a powerful tool for tile construetion. 

The actual value of the enthalpy of hydrogenation of 1,3-butadiene is —243 k,l rnol Both are hydrogenated to the same product, u-biitaiie hence the enthalpy diagram (Fig. 7-4) shows that bnta-1,3-diene is 11 kJ rnol. lower in enthalpy than it ought" to be on the basis of the reference standard, bnt-l-ene. 

Fig. 12. (a) Schematic diagram of cmde unit showing five hot streams leaving the cmde column, and (b) temperature enthalpy diagram for the streams in (a) where A represents the kerosene pumparound B, the gas oil product C, the residuum D, the overhead reflux and E, the cmde. The dashed line is the... 

Fig. 7. (a) Pressure—enthalpy diagram and (b) system schematic for a compound cycle. 

Some values of physical properties of CO2 appear in Table 1. An excellent pressure—enthalpy diagram (a large Mohier diagram) over 260 to 773 K and 70—20,000 kPa (10—2,900 psi) is available (1). The thermodynamic properties of saturated carbon dioxide vapor and Hquid from 178 to the critical point,... 

Although the T-s diagram is veiy useful for thermodynamic analysis, the pressure enthalpy diagram is used much more in refrigeration practice due to the fact that both evaporation and condensation are isobaric processes so that heat exchanged is equal to enthalpy difference A( = Ah. For the ideal, isentropic compression, the work could be also presented as enthalpy difference AW = Ah. The vapor compression cycle (Ranldne) is presented in Fig. H-73 in p-h coordinates. 

FIG. 11-79 Pressure enthalpy diagram for typical two-stage system with two evaporating temperatures, flash-gas removal, and intercooling. 

Fig ure 3-3. The example process in Figure 3-1 is charted on this pressure-temperature-enthalpy diagram dashed lines trace the streams through the diagram. 

Figure B-4. Ammonia pressure-enthalpy diagram. (From Short, Kent and Walls, Pressure-Enthalpy Charts for Selected Fn i neering Substances, Gulf Publishing Company, Houston, TX, 1970.)...

Figure B-7. Freon-12 pressure-enthalpy diagram. (Reprinted by permission and courtesy of E. I, EhiPdnt De Nemours and Co.) Freon and Freon—followed by numerals are DuPont trademarks.

Pressure enthalpy diagram ammonia, 497 carbon dioxide, 498... 

Figure 12-12A. Illustration of isentropic path on log pressure-enthalpy diagram, showing Mollier chart method of finding final temperature and calculation of H for reversible and adiabatic compression. (Used by permission Edmister, W. C. Applied Hydrocarbon Thermodynamics, 1961. Gulf Publishing Company, Houston, Texas. All rights reserved.)...

The use of an enthalpy diagram or Mollier chart is perhaps the most accurate and is an easy method for determining horsepower. Figure 12-70 illustrates the compression paths on an ammonia diagram. 

Figure 13.5. Humidity-enthalpy diagram for air-water vapour system at atmospheric pressure...

Figure 13.7. Humidity-enthalpy diagram lor air-water system — rectangular axes...

The gas formed by mixing two unsaturated gases may be either unsaturated, saturated, or supersaturated. The possibility of producing supersaturated gas arises because the 100 per cent humidity line on the humidity-enthalpy diagram is concave towards the humidity... 

Figure 11 A. Pressure-enthalpy diagram for water and steam 813...

Fig. 1. Free-enthalpy diagram of the carbonylation-decarbonylation of tertiary alkyl cations at 20 0 in FHSOa—SbFs (concentrations expressed in mole litre ). Underlined numbers directly from experimental data.

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