22153 23345

1748.0 1803.5 110.76 116.72 1747.9 1803.4 73.833 77.807 1747.8 1803.4 55.370 58.352 1747.8 1803.3 27.676 29.168 1747.5 1803.0 18.445 19.441

1747.1 1802.8 13.829 14.577

1746.8 1802.5 11.060 11.659

1746.5 1802.2 9.2134 9.7130

1746.2 1802.0 7.8946 8.3233

1745.9 1801.7 6.9055 7.2811

1745.6 1801.4 6.1363 6.4704

1745.3 1801.2 5.5209 5.8219 1745.0 1800.9 4.4131 4.6546

1744.2 1800.2 3.6746 3.8764

1743.4 1799.6 3.1471 3.3205 1742.6 1798.9 2.7515 2.9037 1741.9 1798.2 2.1977 2.3200

1740.3 1796.9 1.8284 1.9309 1738.8 1795.6 1.5647 1.6530 1737.2 1794.3 1.3669 1.4446

1736.0 1792.9 1.2131 1.2825

1734.1 1791.6 1.0901 1.1529

1732.5 1790.3

perature will rise. Table 6.3 shows the thermodynamic properties of superheated steam. Unlike the saturated steam of Table 6.2, in which each pressure had only a single temperature (the saturation temperature) associated with it, superheated steam may exist, for a given pressure, at any temperature above the saturation temperature. Thus the properties must be tabulated as a function of both temperature and pressure, rather than pressure alone. With this exception, the values in the superheated steam table may be used exactly like those in Table 6.2.

Example: Suppose, in the preceding example, that the steam line is carrying superheated steam at 250 psia (235 psig) and 500°F (note that both temperature and pressure must be specified for superheated steam). For the same reduction in heat loss (109,500 Btu/hr), how many pounds per hour of steam is saved?

From Table 6.3 the enthalpy of steam at 250 psia and 500°F is 1263.5 Btu/lb. Thus

109,500 Btu/hr steam savings = -

1263.5 Btu/lb

Table 6.4 Orders of Magnitude of Convective Conductances
0 0

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