Information on Surface condensers

[Lopez Mike]

With my primordial power plant with no condensate pump, my concern is that when my condenser is sized big enough for hard running, it is far too effective for piddling around or even casual cruising at part throttle. The hot well temps drop to blood temperature regularly.

Perhaps, by building some sort of reheat within the keel cooler, I can remedy this problem it would well worth the effort. Now I need to invent or find some low thermal conductivity spacers to keep the return pipe reasonably centered in the condenser outside tube.

[johngriffiths]

Firstly you cannot have condensate at a temperature below that of the cooling water. With a cold lake or sea and if the condenser is of the correct size and the vacuum pump working properly then a high vacuum can be obtained which means there is more work to be got from the low pressure cylinder. Remember that in 1713 the Newcomen engine worked by vacuum alone and so it remained until Trevithick 80 years later. A high vacuum can only be obtained by having a cold condensate

Secondly a cold condensate means the boiler has to work harder to raise the feedwater to the boiling point of the steam. An economiser can be considered to be an extension of the boiler and if the boiler design is efficient, why not make the boiler with some extra heated surface, that is, larger. Economisers can be difficult things to maintain and keep clean on fire tube boilers

With large vessels such as the Danny the trick was to balance condenser vacuum against feedwater temperature against the power needed by the skipper and the quality of the coal being burnt. (and that still leaves out the effect of outside air temperature on flue draft and the heat need to warm the air going to the fires)

John G

[barts]

With my primordial power plant with no condensate pump, my concern is that when my condenser is sized big enough for hard running, it is far too effective for piddling around or even casual cruising at part throttle. The hot well temps drop to blood temperature regularly.

Perhaps, by building some sort of reheat within the keel cooler, I can remedy this problem it would well worth the effort. Now I need to invent or find some low thermal conductivity spacers to keep the return pipe reasonably centered in the condenser outside tube.

A little scrap 12 gage wire wrapped twice around the inner copper tube w/ the ends sticking out and then bent along the tube axis would work fine, and the heat transfer would be minimal. Size it so it fits inside the outer tube easily, of course... or just wrap the wire tightly and let it rest on the bottom.

Some thermometers and weighing of condensate returned to the hotwell will tell you a lot.

- Bart

[Lopez Mike]

Probably something like that would work.

The condenser is curved to follow the hull so I will be putting the new one together while it is straight and then bending it. What ever I use it will need to handle a small bit of side force during the bending process.

[cyberbadger]

For anyone who hasn't seen this before it's a great animation.

Pay attention to the "Engine Pressure and Temperatures" chart on the left. Note the scale changes from PSI to PSIA.

http://www.wslmf.org/discover/technical ... s/cutaway/

-CB

[S. Weaver]

Thanks, Fred. My texts have all this, I am sure, but you are a patient and clear instructor.