What I am getting out of this is that it is there was a significant motivation for steamship engineers to measure feedwater temperatures for boilers and condensers from very early on and to scrupulously record it in order to learn from experience. As soon as Carnot’s results became general engineering knowledge (now when was that, I wonder?) or they figured it out themselves from operational experience they would have been doing this.

It would not only have been the power output that motivated them per se, but also coal consumption. The bigger the difference between the condenser temperature and the steam temperature in the cylinder, the more efficient the engine, no? This motivation would have been especially powerful in the early days of single cylinder engines whose efficiency was so low that most of the cargo was coal fuel and only high paying freight like mail, precious metals and people in a hurry could pay the tab. As double and triple expansion came along, even with the lower coal consumption per hp, the need would have remained as shipping rates fell and the margins on bulk cargoes were slim in comparison to the early high value added ones.

There seems to me a distinct possibility that the bucket-inlet and depth of sampling issues could go back a very long way.

Mike

I think there is a bit of a nomenclature issue: feedwater is essentially condensate. There is some makeup water because of steam leaks in the engineeroom, but it is quite small compared to flows of feed/condensate and is added intermittantly. I guess in the olden days they might have added seawater. Would have been pretty harsh on the boiler though…distillation (or reserve tanks) is the norm for a long times now.

It’s not that hard to set up an evaporater to make fresh water with if you already have a steam system in the ship. The steam gives you heating and also allows drawing a vacuum through a venturi-like device called an air ejector. It’s not like distillation was not known for a while know from chemistry/spirits industries.

Certainly the condenser temperature would matter, though not perhaps as directly via pressure as much as the rate of condensation which, given a fixed engine size, would help determine the power.

I wrote:

“I strongly suspect that for the first 70 years of steamship history, there were no condensers.” I meant distillation equipment, not condensers.

All Watt type engines had condensers, so TCO’s point about taking temperature readings on the sea-water side of the condenser stands as a factor.

As to TCO’s comment that the 1830s steamships are not relevant, he is, of course quite right. Why I made reference to them was to demonstrate that steamships have been around a long time and that there were a great many experiments with steam ship machinery before it standardized on triple expansion in the 1890s. The Great Britain had triangle engines, for example. My point still stands, I think: there could have been all kinds of arrangements tried for measuring feedwater temperature; and it is far from clear when this started – it could have been many decades before the date of 1941 quoted.

I came across a statement that engineers on steam ships would use the bucket method to measure the temperature of the water so as to estimate the maximum power that was possible from the engine(s).

I can see where the temperature of the feedwater to the boiler would affect coal consumption and perhaps steam temperature and pressure.

Would the temperature of feed water to the condenser matter for power output?

Any thoughts, TCO?

I served on conventional and nuclear steam vessels.

The 1830s steamers would be a bit irrelevant to the issue of feewater versus cooling intake, though. I don’t know the history of open cycle steam at sea.