Abstract

In this paper relationships are derived for the expansion of a high pressure fluid from a cylinder of constant or variable volume across a nozzle into a constant pressure atmosphere. This process has many applications in applied thermodynamics. For example the discharge of steam in feedheater spaces through the turbine when the turbine load falls. This is particuiarly important in large power station turbinęs wlrere the energy of the steam causes overspeeding of the machine. The expressions developed allow for heat transfer and internal irreversibilities in the cylinder and in the nozzle. A comparison is then made of this unsteady flow process with a similar non flow equilibrium process in a cylinder and with a process of free unrestrained expansion in a cylinder. Using the concept of high grade energy, it is shown that ail three processes may be analysed in the same manner.