A heat exchanger wherein steam is condensed either in direct contact with cooling water or indirect contact with cooling water through a heat transfer medium separating them. Functions of condenser are:
- To remove the latent heat from the exhaust steam so that the condensate thus obtained can be easily handled by the pumps in the feed system.
- To reduce the backpressure and so allowing a greater amount of work to be done by the engine for a given quantity of steam, thereby improving the efficiency.
There are two types of condensers:
In the surface type, there is a temperature drop of about 8°C from inlet to outlet and the condensate and air leaves from the bottom.
The drop in temperature signifies a loss of sensible heat, termed undercooling of the condensate.
In the Regenerative type, steam flowing along the regenerative passage and up into the tube nests heats the condensed droplets from the tubes so that there is practically no drop in temperature. Air trapped by the baffles is extracted separately.
In practice, there is a drop in temperature of 1 to 2°C and the cut down in undercooling can amount to saving on the fuel of about 1 to 1.5%.
The regenerative condenser is the first direct contact feed heater in the feed system and aided by the air ejector it has a deaerating effect on the condensate.
Condensers for turbines are of the Regenerative type; single or double flow; underslung, i.e. usually hung off the LP turbine casing - the springs act as shock absorbers and support about 1/3 of weight. A single flow can be built for scoop arrangements.