Mollier diagrams

Many of the Vargaftik values also appear in Ohse, R. W, Handbook of Thetmodynamic and Ttanspoti Ftopetiies of Alkali Metals, Blackwell Sci. Pubs., Oxford, 1985 (1020 pp.). This source contains superheat data. Saturation and superheat tables and a diagram to 30 bar, 1650 K are given by Reynolds, W. C., Thetmodynamic Fropetiies in S.I., Stanford Univ. publ., 1979 (173 pp.). For a Mollier diagram from 0.1 to 250 psia, 1300 to 2700°R, see Weatherford, W. D., J. C. Tyler, et al., WADD-TR-61-96, 1961. An extensive review of properties of the solid and the saturated liquid is given by Alcock, C. B., M. W. Chase, et al.,y. Fhys. Chem. Ref Data, 23, 3 (1994) 385-497. 

Mollier diagram for potassium. Basis enthalpy = 0.0 oal/g atom at 298 K entropy = 15.8 oal/(g atom-K) at 298 K. (Aerojet-General Rep. AGN8194, vol Reproduced hy permission.)... 

Steam Rate Enthalpy data can be obtained from Mollier diagrams or from steam tables (see Sec. 2), from which the theoretical steam rate can be calculated. For example, a throttle inlet condition of 4137 kPa (600 psig) and 399° C (750° F) gives an enthalpy of 3.2 MJ/kg (1380 Btu/lb), and if the end point is at 348 kPa (50 psig), then adiabatic expansion is to 2.69 MJ/kg (1157 Btu/lb). This gives 0.52 MJ/kg (223 Btu/lb) available, and the theoretical steam rate is calculated from the Btu equivalent per Idlowatthour or horsepower-hour ... 

FIG. 29-23 Mollier diagram showing ASME-IEEE steam-turhine standards. To convert British thermal units per pound to kilojoules per kilogram, multiply hy 2.328 to convert British thermal units per pound-degrees Ranldne to joules per gram-Kelvin, multiply hy 4.19 and to convert poiinds-force per square inch to Idlopascals, multiply hy 6.89. 

Plotting these pressures and temperatures on a Mollier diagram (Figure 4-115), makes it possible to compare the amount of available energy for both examples. The available energy of Example 1 is 71.5 Btu/lb as compared to 110.4 Btu/lb for Example 2. In other words, increasing the inlet pressure from 30 to 42 psia and the temperature from 1,200 to 1,300°F results in over a 50% increase in available energy, which translates directly into recoverable power. 

Application of Hot Gas Turboexpanders 231 TH EXPANDER TYPICAL MOLLIER DIAGRAM... 

Figure 4-115. Pressures and temperatures from Table 4-11 transferred to Mollier diagram.

Equation 2 will yield the same result as the Theoretical Steam Rate Tables (Reference 10). Therefore, this is a handy way of getting theoretical steam rates when only a set of steam tables sans Mollier diagram are available. 

STATE VALUES OF HUMID AIR MOLLIER DIAGRAMS AND THEIR APPLICATIONS... 

Properties of humid air are usually described by means of the Mollier diagram. The Mollier diagram is constructed for a certain air pressure, normally for the value... 

The abscissa of the Mollier diagram is humidity x. The axis is provided with a pitched scale. A straight line is drawn with a 45° angle to the abscissa, and it is provided with an enthalpy scale hj ) according to the equation hj. - = X = 2501.6 X, kj/kg (Fig. 4.8). Consequently the enthalpic scale... 

When the saturation curve (

relative humidity ([Pg.74]

Construct a Mollier diagram for air, when the total pressure of air is 875 mbar. 

With high temperatures the x values will not fit into the diagram. Then the hj values have to be calculated with smaller x values in order to draw the isotherms. In Table 4.6 these values are calculated with values x = x q% at various temperatures. Drawing the fundamental axes and isotherms with the instructions given above and the saturation curve with the help of Table 4.6 leads to the Mollier diagram in Fig 4,10u. 

The total pressure thus has no importance. If this result is. sought from a Mollier diagram by finding the intersection of the humidity line (jr = humidity of air = constant) and the saturation curve, which gives the dewpoint temperature, a diagram constructed for a pressure of 9.S0 mbar should be used. A decent ap-proximation can be found from a diagram constructed for pressure p 1 bar. 

So the state point of air in the Mollier diagram is shifted in a direction where the dependency between the enthalpy and the humidity change according to the Eq. (4.133) is valid. This result is illustrated in Eig. 4.12. 

Eable 4.7)Draw in the Mollier diagram at the 14 °C point of the saturation curve (a) the state change line of the adiabatic humidification and (b) an auxiliary line, associated with the wet bulb temperature measurement, by means of which the state can be defined. The pressure of air is p = 1 bar. 

In practical calculations the. Mollier diagram s constant enthalpy iine can be used as the auxiliary iine for the wet bulb temperature line to a satisfactory... 

As an example of using a Mollier diagram in defining the state of air, we can take a typical measurement from the local exhaust hood of a paper machine. Tbe temperature of the exhaust air is 82 C and its wet bulb temperature 60 "C. In Fig. 4AQd we move from the saturation curve at the point 60 °C straight up along the constant enthalpy line ( = 460 kj/kg d.a.) until we reach the isotherm... 

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