The British Steam Car Challenge

Van Cutter Romney sends us word of a British steam-powered car that will attempt to set a world record speed of 200 mph. The car, constructed on a tubular chassis, holds four boilers that deliver four megawatts of power, producing 300 bhp. The current record of 127.659 mph was established in 1906. More photos and specs at the Steam Car Club of Great Britain's site.

Comments

Damned inefficient

[overshoot]

Four megawatts turning into 300 bhp?

Should be well over 4000 bhp, since one bhp is 746 watts. Looks like an amazing amount of conversion loss there.

Re:Damned inefficient

[xero314]

The IC engine is far more efficient in comparison. If Internal Combustion is so much more efficient why is the vast majority of energy produced on earth is converted to electricity through turbines rather than internal combustion driven generators? Gas turbine engines have been produced with a energy conversion efficiency of 46%, as compared to ICs which have reached 42% (both maximums taken from working models not theoretical). It is also easier to addapt heat recovery systems to turbine engines than it is to internal combustion. Now multi stage steam turbines actually surpass Both the IC and the Gass turbine and are capable of reaching 95% isentropic efficiency. I just think you are missing some factors in your efficiency equation.

Re:Damned inefficient

[LabRat]

Well, yes and no. It's true that the majority of the thermal energy is removed after the turbine stage..but that doesn't mean that 75% of the initial energy is lost uselessly to the environment. Rather, the act of condensing the steam back into water drastically reduces the exhaust pressure and increases overall flow rate through the turbine...causing substantially more mechanical energy to be produced than would otherwise be made. The effect can be calculated quite accurately using 2nd Law analysis. It's the fact that the water-steam volume difference is so great that makes the Rankine cycle so successful. Even at quite high pressures, an exhaust stream of steam can become nearly a vacuum (or at least 1 atm) practically on-demand simply by cooling it to the condensation point. That's the job of the big cooling lakes and/or nearby natural bodies of water that Rankine-based power generation plants are built near.

All that said, there's no indication from the article that the powerplant is based on the Rankine cycle. Steam power generation plants can achieve thermal efficiencies well in excess of 30%...with some of the newer designs pushing the 50% mark. This particular article is claiming a bit over 5.5%. A lot of that can be attributed to scale (smaller heat engines typically have lower thermal efficiencies)...but I hope there's a typo in there somewhere else color me underwhelmed.

Re:Damned inefficient

[imsabbel]

Maybe because steam engines arent turbines?
You know, Rankine cyle vs Brayton cycle....

Re:Damned inefficient

[DigiShaman]

The IC engine was developed as a replacement for steam powered piston locomotion and paddle wheel boating (think river boats on the Mississippi).

For modern electric plants, steam turbines (running on natural gas or coal) are used and often running with a constant load. This makes for better optimization. In fact, all nuclear power plants use steam turbines. But if you think running a steam turbine in an automobile is far more efficient than an IC, you're mistaken. We don't have heat recovery technolgy that scales down small enough to be as effective as the ones running our power plants.

Re:Damned inefficient

[xero314]

Maybe because steam engines arent turbines? That's interesting since what we are discussing here is a specific entry in the British Steam Car Challenge who's "Motive power is from a two-stage steam turbine [which] drives a gear train with a 5:1 ratio for a wheel speed of 3000 RPM at 200 MPH". Now since you were responding another post which was a comment on the output of the aforementioned turbine powered car, and there was no reference to "steam engine" made until you last post, would you like to go an RFTA and then get back to us?

Re:Damned inefficient

[Robber Baron]

Maybe because steam engines arent turbines? Not true.

The Pennsylvania Railroad built a hugely powerful steam turbine locomotive, and there were others as well. 6900 HP is HUGE for a single steamer, but that much HP is usually only needed for freight trains, and PRR's monster was terribly inefficent below 40 MPH, and most freight trains spend a large portion of their time running slower than that. Also diesel-electrics were starting to come online, which are much more efficient at slower speeds (about 25 MPH is the most efficient speed for a diesel-electric freight locomotive). It might have been useable pulling a fast, heavyish, passenger train, but the newest competition of the day had wings...

Re:Damned inefficient

[Trackster]

4MW is the _capacity_ of the boilers. Chances are, they never use all that capacity. That's just the size boiler they needed to maintain a large head (charge) of steam at high output for a long time.

steam car dragster

[secPM_MS]

The problem with steam engines is the condenser system, which tends to be bulky and weigh a lot. If you are going to go open cycle, an appropriate choice for a short distance racer, a high pressure system can have very high power. In such a situation you have your high power boilers fed by a high pressure pump and exiting a turbine, which is geared down to the wheels. ZOOM!

Re:Steam isn't an energy source

[OverlordQ]

Thank you for personifying the typical Slashdotter by not Reading the Farking Article.

From TFA's Seventh Sentence:

Motive power is from a two-stage steam turbine, fed by a boiler fired on LPG.

Thank you, come again.

Re:Not really a steam car.

[AKAImBatman]

This is not a steam car in the conventional sense, as it does not burn coal.

If you think a car needs to burn coal in order to be a "Steam Car", then you're seriously out of it. Conventional steam cars burn a variety of fuels, including gasoline.

http://en.wikipedia.org/wiki/Steam_car

Steam engines are valued for their excellent power to weight ratios, general efficiency, and greater torque capacity. They also have fewer moving parts so maintenece schedules are quite good, as long as you don't leak your working fluid. (i.e. Water) Thankfully it's quite easy to replace lost water, and can be done as part of regular maintenece. (Think: Flushing and replacing water while changing oil.)

Or maybe you're trying to be funny. It's hard to tell. :-/

Steam Cars Are a Tough Choice

[tjstork]

Comparing a ground based turbine set up to a mobile IC is a bit off.

A steam plant on the ground actually spins, in the US, at a constant 60rpms when all is said done, that's how we get power at 60hz. In fact, one of the little known things about the power grid is that demand on the grid can actually "pull" on the generators, turning them into motors or slowing them down. In extreme cases, it is possible to physically damage the generator. Tales of bent shafts due to fluctuations in demand are common.

It should be obvious from that anecdote alone, that the physical requirements for land based power stations are vastly different. I rule out natural gas as a solution right away simply because its widely known with the industry that the country screwed up in the 1990s and built too many gas peakers and quite literally burned all the natural gas in Texas. Coal is coming back into vogue because the administration is friendlier and it is so cheap. So what does a coal plant do? Coal based plants today have onsite apparatus to powderize and dry the mile long trains of coal that they burn every month. Because the coal is powderized so finely, dust is everywhere. Coal plants are not clean. Even with today's high efficiency, combustion is not perfect and neither is the water used to make the steam with. Crews must periodically bring down the boiler, get inside there, and clean it out. It is truly a dirty job that requires special, well paid people to do. I should add, as an aside, that many coal plants are so old that utilities often have machine shops of their own to make their own parts with for maintenance.

All of this stuff weighs a lot. Automakers do a remarkable job fitting an engine and a motor / generator into a hybrid car, but I think adding a boiler would throw off the whole scheme. In order for a boiler to be really good, you need a lot of pressure, and in order to have pressure, you need a strong boiler and that means weight. Then, in addition to your fuel, you need to have a ready supply of water everywhere. If you read about the history of the Baldwin Locomotive Works, you'll see that they tried to bring steam engines into a competitive league with the diesels emerging in the 1930s, but the water was the deal breaker.

Bottom line is, if you wanted to have a mode of transportation that has you running for fuel and water both, asks you to bring a shovel along so you can shovel your ton of fuel a week into it, and requires you to do a periodic job of scrubbing out dirty tubing, and, in an accident, may literally blow up and kill you and everyone else in your car, then steam transporation is for you.

But I think steam power is best left to the professionals at your local energy company, and your best way to use it is with an electric car.

Re:Pointless

[DerekLyons]

What's the point of this? Steam reached the peak of its development for transportation in the 1920s.

The designers of naval powerplants would be surprised to learn this - as they were making performance and efficiency gains right up until (fossil fuel combustion) steam went out of fashion for new builds... Within the last twenty years. Word on the street is that guys over on the nuclear side of the house are still making a few improvements to the steam side of the cycle even today.

Re:Steam isn't an energy source

[Hungus]

I thought iron was the first to require a net energy input, but I can't be bothered to look.