2.4.5 Hood loss
Another loss which occurs between the final stage and the condenser inlet is a pressure drop known as hood loss (Fig 1.20).
Normally the condenser static pressure is less than that at blade exit. The steam expands in the hood which joins the exhaust of the LP cylinder to the condenser inlet. The expansion converts enthalpy to kinetic energy which is then converted back to heat by flow friction losses.
In some cases the hood loss is negative and the condenser pressure is higher than blade-exit static conditions. This occurs when the steam kinetic energy is converted to pressure, a process known as diffusion.