An air-cooled condenser is however, significantly more expensive and cannot achieve as low a steam turbine exhaust pressure ( and temperature ) as a water-cooled surface condenser.
12.
More advanced exhaust brakes have exhaust pressure modulation ( EPM ) that controls the back pressure which in turn improves the braking performance across a range of engine speeds.
13.
Most turbopumps have a Holweck pump ( or molecular drag pump ) as their last stage to increase the maximum backing pressure ( exhaust pressure ) to about 1-10 mbar.
14.
Turbocharging allows for more efficient engine operation because it is driven by exhaust pressure that would otherwise be ( mostly ) wasted, but there is a design limitation known as turbo lag.
15.
The amount of power in the gas is proportional to the difference between the exhaust pressure and air pressure, and this difference increases with altitude, helping a turbocharged engine to compensate for changing altitude.
16.
A supercharger, by the way, is a belt-driven air pump that forces the gas and fuel mixture into an engine to boost power, similar to the more-common turbocharger, which is driven by exhaust pressure.
17.
The advantage of this arrangement is that leakage, via the gland which seals the steam chest from the operating rod of the valve gear, is much less of a problem when the gland is subjected to low exhaust pressure rather than full boiler pressure.
18.
The air coming into a ram is forced to slow down before it enters the combustion chamber and that increases the pressure well above that of the exhaust pressure-which is lower because it accelerates .-- talk ) 22 : 14, 19 March 2012 ( UTC)
