Thread: Brunel's "Gaz Engine"

Can anyone tell me more about this? Brunel wasted a lot of time and effort on this machine that came to nothing. What was it and on which principles was it based?

I got curious my self so I googled it. 15 minutes netted me very little information;

in 1833, he finally abandoned a decade-long private project to develop an engine — he called it a "gaz" engine — powered by gas pressure as an alternative to steam.

Source: http://www.engineering-timelines.com.../brunelIK4.asp

Pneumatic engine?? meh...

Thanks spirytus. Bit of a weird one this. The man spent a decade researching this and yet I can't find a thing about it. Brunel was no dummy. He must have been on to something. He must have been sponsered/funded. No drawings, no prototypes, no anecdotal evidence?
All the engineers I've ever met fall over themselves at the opportunity to explain how a machine works to an enthusiastic layman.
Would anyone even care to have a guess at what IKB was working towards?

There were several designs involving compressed air engines and they seem to be feasible, the problem is that you need energy to compress air, and the total efficiency must be considered in the whole process.

I know I'm a bit late, but I was googling around trying to find out more about something that I came across in a book, finding nothing but the fact that you seemed to know less than me, I have taken the time to type out the relevant passage. I hope this answers your questions!

Put simply, the scheme was to generate gas from carbonate of ammonia and sulphuric acid and pass it into two surface condensers which were alternately heated and cooled and which communicated through expansion vessels and valves with a power cylinder. When the gas in one condenser was held in its condensed state by passing cold water through the condenser tubes and the the other was heated but the circulation of hot water, the difference in pressure between the two vessels was thirty-five atmospheres. This was the power which Brunel endeavoured to harness and which he believed at the time might superseed the power of steam
so promising did the idea seem that the experiments were heavily subsidised, even the Admiralty making a grant. the technical problems which had to be solved in order to translate theory into practice were immense and that they were solved is extraordinary when we think of the very limited metallurgical knowledge at that time. The gas condensed at a pressure of no less than 300 atmospheres, while popes and pipe joints had to be made to withstand pressures of 1500 lbs per square inch. this in an age when, in steam engineering, 50 lbs per square inch was often considered dangerously high. cast iron was obviously useless and a type of gunmetal was eventually evolved for the pressure vessels. Brunel, just after the closure of the tunnel at rotherhide (under the Thames, first attempt) spent six months working with an assistant named Withers. Brunel's notes and sketches suggest an apparatus just about as safe as a ticking time-bomb, and the most remarkable thing is that he and Withers failed to blow themselves up! At long last, however, Brunel was forced to admit defeat. On January 30th 1833 he wrote "Gaz - After a number of experiments I fear we must come to the conclusion that (with carbonic acid at least) no sufficient advantage on the score of economy of fuel can be obtained over steam power"

Source: "Isambard Kingdom Brunel" by LTC Rolt (1957) pgs 41,42

Will

The "gaz" must have been carbon dioxide. At 300 atmosphers it would be in the dense phase, meaning it is above the critical point and is neither a true gas nor a liquid. Dense phase is the condition of CO2 that is currently pumped underground for secondary oil recovery or sequestration, and the pumps are quite specialized. I'm wondering if Brunel was somehow exploiting the fact that dense phase fluids have zero latent heat so expansion and contraction requires little heat removal and addition. Not really sure, haven't thought it through. Quite amazing that Brunel imagined he could safely contain 300 atm. with then available metals.

The CO2 would also be wet from the reaction, water being another product. Wet CO2 is highly corrosive, so just another little problem he would have had to deal with.

Thanks for the info - I hadn't heard of this before.