An Engineer in Wonderland – Why they won’t let me be a mechanical engineer

steam-from-train.jpg Given the problem: How do you pump water into a boiler using only steam pressure from that boiler? I would come up with some sort of piston-based steam engine connected to a piston-based water pump. Which identifies me as a thermodynamic dunce – as a much cleverer no-moving-parts answer was invented 150 years ago; which I came across in a book on steam engine technology. Basic thermodynamic theory flourished in the mid-19th century, which puzzled me until Richard Wilson, editor of Electronics Weekly, explained it thus: “Because they had big brains and nothing else to think about.”

I hadn’t though of it like that, but now I agree. When the steam engine was the state of the art, lots of clever people got involved. Anyway, the water injector is unbelievably clever and I suspect any self-respecting member of the IMechE would understand it immediately. I don’t. If you are interested – there is a diagram and explanation in Wikipedia (click the image below). ejector-or-injector.png The simple bit is that steam from the boiler goes through a narrow nozzle and sucks up water – I remember this bit from the ‘scent spray’ demonstration at school. Then it gets cleverer, as the mixture of steam and water goes through a convergent-divergent nozzle which, through the magic of Carnot, comes out at a higher pressure than the boiler. Wow. The whole steam engine book is full of equally clever mechanisms, which I hope are still taught to mechanical engineers as someone ought to be remembering them just in case society needs them in the future. Just like electronic engineers are remembering how thermionic circuits work – oh…. ‘Alice’ (Picture “Valley Railroad Steam Engine, Essex CT” – Professor Bop, under Creative Commons Attribution Licence)

Related Tech News

Share your knowledge - Leave a comment