rjk and I had an argument as to whether steam powered cars are feasible. I say that there is some technical problem with making a car powered by steam. * Bob says that the only reason there aren’t steam powered cars is that the gas engine took off first (the Beta argument ).
Since neither of us has enough knowledge to disprove the other, we come too y’all, oh Dopers who know all. Which one of us is right?
*a piece of info I got from a movie about Howard Hughes and thus a questionable source.
There is no reason why a steam car can’t be built - in fact, for the first couple of decades of the 1900’s there were numerous steam cars in production. They lost popularity after the introduction of the electric starter for gasoline cars was invented, as steam cars would take several minutes to warm up enough to run.
Define feasible. Steam powered cars are certainly possible, and modern technology could alleviate some of their inherent problems. But the one thing you can’t get around is that there needs to be power to produce the steam. Compared to using that power to directly run the engine, there’s more complexity and less efficiency in making steam. Why bother?
Steam didn’t fall by the wayside because internal combustion engines took off first. It fell by the wayside because internal combustion engines do a better job with less problems.
So judging from those links, steam cars have a number of problems. One is that you apparently go through a gallon of water every 10 miles. Maybe we can do better now, but to get the current 300+ miles cruising range of a car, you’d need an extra 30 gallon tank (at 8lb/gallon). Not good for mileage.
You have a boiler under pressure with live steam. Not something you want to be around in an accident.
Boilers in general need a lot of maintenance. Any time you run steam through pipes, you have to worry about corrosion.
I agree there are problems, but I think they could be solved, or at least reduced.
Gary T’s concern over “more complexity and less efficiency in making steam” is, I think, mistaken. Steam is easy to make, and the cylinders deliver power on every down-stroke, instead of every other one like IC engines.
The second article Johnny L.A. linked seems to suggest that the Stanley’s boiler is kept full of water (except for the fire tubes). Start-up time could be shortened somewhat by heating it while empty and then spraying water in as needed. That also reduces the danger from a live boiler that Finagle noted. The 10 miles per gallon of water might well be improved. (I don’t know where the Stanley’s water was going!) Corrosion depends a lot on the materials - stainless steel or even platinum plating might help.
I’ll look for some cites on modern steam engines, and post again in the morning.
Steam engines are particularly useful for train locomotives because they deliver maximum torque at zero RPM–very helpful in getting a massive train moving. This quality was not considered useful enough in an automobile to justify the drawbacks inherent in the engine. Modern locomotives are often deisel-powered generators driving electric wheel motors, because this way the diesel motors can spin up to their best power-output and electric motors also develop maximum torque at zero RPM.
Of course some drawbacks might be solvable now, but that was the reasoning at the time. You can attach condensers to the steam exhaust to capture most all of the water blown off, for example–and later locomotives did use these. But at the time, for light loads, it was simply easier to make a smaller gasoline engine and ust that instead.
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From the Wiki: “Jay Leno, host of the Tonight Show, owns and drives a Stanley Steamer to work. Even though it leaks water, it remains one of his favorite cars in his auto collection”. Well he just went up my coolness ladder, although admittedly from a very low rung.
A decent steam engine can be a lot more efficient than an internal combustion engine. The determining factor being the temperature difference between the steam and the ambient environment. The greater the difference, the higher the efficiency. However, the amount of hardware required to operate and maintain an efficient steam propulsion system is prohibitive. It is also scary to consider the aftermath of a collision in a steam powered vehicle. Not only is there fuel to worry about, you’ve got a fire going (to boil the water) and scalding steam added to the mix.
What I have always wondered is why no one has come up with a way to increase the efficiency of an internal combustion engine by using the incredible amount of heat it generated to operate an auxiliary steam or freon turbine. Once your gasoline engine gets nice and warm, use that heat to boil a liquid to run a turbine for extra power. The ultimate hybrid vehicle would have gas, electric and steam power. Then you could see gas mileages in the triple digits on high performance vehicles!
There is certainly heat in the exhaust, but you seem to be saying that this could be harnessed to yield at least as much power as is already being produced by the engine. Given that the turbine you propose must itself reject heat to the atmosphere, I think this estimate of the additional power available is very optimistic.
Perhaps utilizing the water jacket in the block could help.
Extend the jacket to the exhaust manifold and inject the boiling hot water…when at temperature…directly into the firey hot exhaust stream. That would certainly convert the water into high volume, high pressure steam with energy to power a turbine for auxiliary power. A down-stream condenser can recover the water in liquid form
Such a set-up would be suited for long-haul trip vehicles like buses and tractor-trailers, not short-trip stop-and-go city traffic cars.
But then you’re taking energy from the existing engine, thus forcing it to burn more fuel.
It very hard to get a free lunch thermodynamically. And a large number of clever engineers have been at work on the internal combustion engine for over a century. So it generally pays to look carefully at claims of simple, quick, large jumps in efficiency.
I didn’t get back as soon as I thought, but I’ve found a little more info.
The thread linked above has some, and an earlier one linked from there has even more. (The second one has a bit of a fight in it, but there are more links on page 3.) Wikipedia has several pages, notably their “Steam car” entry.
This page talks about a steam-powered Wankel engine, unfortunately with no details, and this says steam power is “The Most Suppressed Invention.” (Yes, he sounds like a crank to me too.)
Back in the late 1950s the Wright company tried an novel idea for extracting extra power from their large airliner piston engines. The Wright R3350 (3350 cu in, 2200+ HP, 18 cylinders, 36 spark plugs, 2 geared superchargers, etc.) had what they called Power Recover Turbines, or PRTs. These where essentially 1/2 of a turbocharger, with the usual turbine wheel placed in the exhaust stream, but there was no compressor assembly. Instead, the turbine shaft was geared to the main crankshaft via a gearbox & overrunning fluid clutch. The idea was to add up to 20% to crankshaft horsepower at high power settings using “wasted” heat/energy in the exhaust.
How well did it work? It did make the 20% increment on non-PRT horsepower with little or no adverse effect on fuel consumption. But after that it went downhill. They were rather unreliable even by the low standards of the day, and costly even by the cost-is-no-object standards of pre-deregulation aviation. No other engine design that I’m aware of ever tried, much less succeeded at that particular power augmentation strategy.
Perhaps the best thing about those old engines was their oil consumption. 2 GALLONS per hour per engine was typical. My Ford truck, with an engine 10% the displacement but turning about 50% faster hasn’t burned or leaked 2 gallons yet in 3,000 hours in operation.
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