Steam-Water Critical Flow through Pipes

Abstract

Steam and steam-water flashing flow were used to obtain critical† discharge pressures for pipes over the stagnation enthalpy range 230 to 1200 Btu/lb and for the critical pressure range 14 to 64 lb/in² abs.

Pipe sizes used were 3, 6 and 8 in. in diameter. The following empirical equation covers the data with an accuracy of ±3 per cent:

where G is mass-velocity, lb/sec.ft², h is specific stagnation enthalpy, Btu/lb, and P is the critical discharge pressure, lb/in² abs.

It is also shown that the amount of energy flowing along a pipe can be obtained accurately to within ±10 per cent if the critical pressure only is known; that is, the stagnation enthalpy is not known.