Steam

[IanD]

Gas turbines are horribly inefficient unless run continuously at full power, which is why they're fine for helicopters and APUs where weight matters and power is always high. They're a non-starter for cars (the 150hp Rover gas turbine car did about 8mpg), and boats unless they were just used as an on/off generator (or for short high-speed "boost" power in very fast pursuit boats).

 

Steam turbines are only efficient when large and running at full power with very hot/high pressure steam at the input and into a near-vacuum (condenser) at the output -- great for power stations and ocean liners, again not for boats (and certainly not cars).

 

Unfortunately if you want decent efficiency over a wide range of loads there's almost nothing that will beat a diesel engine...

 

(except a battery-electric boat where the electricity comes from huge efficient power stations, or even better renewable sources).

[larryjc]

Gas turbines are horribly inefficient unless run continuously at full power, which is why they're fine for helicopters and APUs where weight matters and power is always high. They're a non-starter for cars (the 150hp Rover gas turbine car did about 8mpg), and boats unless they were just used as an on/off generator (or for short high-speed "boost" power in very fast pursuit boats).

 

Steam turbines are only efficient when large and running at full power with very hot/high pressure steam at the input and into a near-vacuum (condenser) at the output -- great for power stations and ocean liners, again not for boats (and certainly not cars).

 

Unfortunately if you want decent efficiency over a wide range of loads there's almost nothing that will beat a diesel engine...

 

(except a battery-electric boat where the electricity comes from huge efficient power stations, or even better renewable sources).

Whilst I agree with this partly - gas turbines have an incredibly good specific fuel consumption when operating flat out as you say. The Rover car suffered from more than poor efficiency though. In those days the fuel management systems and compressor designs meant that they were not responsive enough for normal car use. However a small gas turbine connected to a generator and a few batteries to smooth out delivery could be ultra efficient - Volvo experimented with one some years back and even Chrysler had an ambition to run such a hybrid system at Le Mans. Then of course why is no one using Sterling engines??

[Arthur Brown]

http://www.wrenturbines.co.uk/turboprops/wren-44-i-turbo

 

It's a 7.5bhp shaft out turbine that runs on kerosene that you could put in your pocket.

[Arthur Brown]

The thermodynamic efficiency starts as the ratio of the absolute temperature of the steam in over the steam out, and goes down from there) so high temperatures are needed as are high pressures which usually means specialist boilers with boiler inspections. The highest performance power turbines are VERY fussy about the purity of their feed water, degassed water that has been filtered and then either reverse osmosis or ion exchange purified is a good start, but as the water/steam temp gets over 1000c then silica becomes soluble in the vapour and then subsequently deposits on the turbine blades as the steam cools, this eventually upsets the turbine shaft balance and the machine shakes itself to death if not cleaned often enough.

[peterboat]

I want one

 

Peter

[Arthur Brown]

I reckon that one of those turbines would spin an automotive alternator quite adequately (and fast enough!)

[Timleech]

I reckon that one of those turbines would spin an automotive alternator quite adequately (and fast enough!)

 

That crossed my mind, too, but what's involved in the 50 hour service? Could be very expensive electricity!

 

Tim

[George94]

Whilst I agree with this partly - gas turbines have an incredibly good specific fuel consumption when operating flat out as you say. The Rover car suffered from more than poor efficiency though. In those days the fuel management systems and compressor designs meant that they were not responsive enough for normal car use. However a small gas turbine connected to a generator and a few batteries to smooth out delivery could be ultra efficient - Volvo experimented with one some years back and even Chrysler had an ambition to run such a hybrid system at Le Mans. Then of course why is no one using Sterling engines??

Coz they don't work.

[DHutch]

Going back to my original post, it seems that steam in the sense of modern technology is a non starter. All the boats mentioned here and all the web sites I've found are based around either vintage engines or rebuilt versions thereof.

I would be inclined to agree.

 

Quite simply there is not a compact or efficient steam based solution commercially available or otherwise, I have once read an article on a compact steam plant for automotive application, based on on a liquid fuelled flash steam generator and a rotary/wankle engine, but it was far from a finalised item.

 

I don't expect you could make a turbine based steam plant that would get anywhere near to a desirable size and efficiently needed to make it practical for a boat. Ditto a gas turbine. The fact is that modern IC engines are actually pretty good!

 

I would use diesel for fuel. Much cleaner and more convenient. You could probably convert an old Rayburn. Or two or three.

There are diesel fuelled steam narrowboats, and a few lpg launches around, but the plant used is so massively inefficiently compared to a conventional IC engine the costs are enormous.

 

As I mentioned above, we burn around 100kg of coal in a 10hour day covering a fairly typically 25lockmiles a day, which at the current price of £315/ton is £31 and a quite manageable £3/hour or £1.25 a lock mile.

I only have indirect figures for diesel boats but I understand that £100 for an gentle 8 hour day, so maybe £12 an hour or £6-8 per lockmile.

 

Suspect it was a tounge in cheek comment, but obviously a Rayburn would not work as a steam generator as it would simply not be able to sustain the pressure, or I suspect heat output, that would be required for running steam plant.

 

Our boiler runs at 200psi (14bar) with an quoted evaporated rate of 600lb/hour or 270/lhour, have as yet not attempted to varify this output, nor calculate the average power output of either the boiler or the fire, I expect the fire is in the region of 50-80kW as a figure in the air figure. With the engine producing maybe around a tenth of that.

 

##

 

We have looked at making a Tesla steam turbine to spin an alternator, but in practice I think if you wanted a small generator a 2*2inch single cylinder reciprocating steam engine would be closer to the mark, and in practice the alternator we have driven of the main engine/propshaft supplies our needs and you would never raise steam just to make electricity.

 

Coz they don't work.

They work all right, the issue is that they create a large amount of low-grade 'waste' heat. So you if you have a use for the said low grade heat, they can work out to be practical as has been done with small generating sets that double as a heating source. But again, it would not be practical to usefully use the low grade heat in the quality an engine used from propulsion would generator, and hence they become horribly inefficient.

 

 

Daniel

Edited January 11, 2015 by DHutch
More comments added.

[bizzard]

An invention of mine was a water injection engine. Just play a blow lamp on the cylinder head whilst injecting timed drops of water. It flashes into steam, velly plowerful.

Flash steam boilers can be dangerous to keep under control.

[bizzard]

What type of reversing valve gear does the steam engine in your boat have Dan? Slip eccentric, Hackworth, Joy, Stephensons link ? Or is it a single acting oscillating engine ?

Edited January 11, 2015 by bizzard

[peterboat]

Coz they don't work.

Thats strange mine works on my wispergen I will have a word with it and tell it to stop working at once I mean fancy making all that electricity and hot rads outrageous

 

Peter

[George94]

Thats strange mine works on my wispergen I will have a word with it and tell it to stop working at once I mean fancy making all that electricity and hot rads outrageous

 

Peter

 

Short statement: "They don't work".

 

Long statement: They produce a huge amount of heat for very little power, so are only suited to applications where they are primarily a source of heat, with a small amount of power generation as a by-product. As a stand-alone source of power they are so inefficient that it is fair to say - They don't work!

 

Happy?

 

Coz if they did work, people would use them.

[Ian Mac]

I think you need to watch this space - http://www.e-catworld.com/2015/01/09/on-e-cat-powered-vehicles-zack-iszard/

I know 99.9% of the people on here will think this is mad, however its happening, and will be here in the very near future. Very expensive version in 3yrs time. Mass produced in 7yrs.
All that this guy writes will apply to boats just as well as cars and Lorries Lorries will be first as 1/2MW units will be easier to build. So its a e-cat powering, a turbine powering, batteries powering, Capacitors powering, motor, which moving the boat. A 30bhp unit will be about the size of a 30bhp diesel engine. Some things I suggest are not required probably the most of the batteries and caps as its a canal boat so we do have time to wait and don't need to turn a key and go.

--

Ian Mac watching the future

PS be very careful if you take the piss as I will enjoy pouring it on you later!!!

[cuthound]

Stirling engines (In a commercial environment), simply don't work, as I described in an earlier thread here.

 

http://www.canalworld.net/forums/index.php?showtopic=70353&hl=+cuthound%20+stirling%20+engine&page=3

 

Post #51& #56

 

ETA post numbers.

Edited January 11, 2015 by cuthound

[IanD]

The problem with Stirling engines -- and steam engines of a size that could be fitted in a boat -- is that like any other heat engine the efficiency is limited by the temperature of the heat source (hotter is better) and the heat sink (cooler is better). Efficient steam engines (like in power stations) need to run very hot and at very high pressure and exhaust into a near-vacuum, none of which is practical or safe for a narrowboat. To be efficient Stirling engines need very exotic materials and construction to allow the "hot side" to run hot enough, and again this is not really practical -- if this isn't done they do dump a lot of heat for a given output power -- they're also difficult to throttle up and down quickly. In a narrowboat it would be difficult to get either to even reach half the efficiency of a diesel.

 

Of course if you don't care about fuel consumption both have many advantages over a diesel, external combustion means lower levels of most pollutants (but not CO2) and much less noise and vibration.

 

Gas turbines might make seem to make sense as a small quiet (well, given enough soundproofing and silencing -- gas turbines are not exactly quiet, as anyone who's been close to one running will know) generator, running at full power to charge a battery bank and then off when not needed. Unfortunately gas turbine efficiency tends to decrease with small sizes because of things like leakage, a 100hp turbine is considerably less efficient than a 1000hp one but probably costs almost as much to make because the machining and assembly tolerances are so critical. The 7.5hp Wren one that Arthur noted consumes about 10.6l/hr flat out, which is the same as a Beta 50 while generating 15% of the power -- if the diesel is 40% efficient, this makes the turbine 6%...

 

(I measured the Rover gas turbine at about 8% in the engineering lab at Cambridge)

[Captain Zim]

Better still would be steam-electric, instead of needing a large boiler to cater for the occasional need for full power a smaller boiler could supply a small steam turbine driving an alternator to charge batteries for electric drive. Turbine could be run in near silence for long hours, even 24/7 perhaps. More flexible than steam alone.

 

ETA: Problem is finding a true miniature steam turbine, there is one in existence somewhere, built by RAF apprentices I believe, but otherwise none I think.

http://www.greenturbine.eu/en/home.php

 

I emailed them a few years ago and they've sent updates ever since. Seems a genuine product.

[nb Innisfree]

http://www.greenturbine.eu/en/home.php

I emailed them a few years ago and they've sent updates ever since. Seems a genuine product.

Looks a nice bit of kit.

[IanD]

Looks a nice bit of kit.

Same problem (or worse) than a small gas turbine, lousy efficiency -- not an issue if it's running off "waste heat" (steam at 200C/160psi) but would be if this was the feed from a boiler, fuel consumption would be maybe 5x that of a diesel generator of the same power...

[Captain Zim]

Same problem (or worse) than a small gas turbine, lousy efficiency -- not an issue if it's running off "waste heat" (steam at 200C/160psi) but would be if this was the feed from a boiler, fuel consumption would be maybe 5x that of a diesel generator of the same power...

Yes I think in one of my early emails whilst this was still a prototype I asked about the efficiency and they never got back to me on it. I haven't read through the new website fully. What is the efficiency? I suppose the only advantage is that the fuel can be anything (within reason) so it could be cheaper in that sense.

[peterboat]

Stirling engines (In a commercial environment), simply don't work, as I described in an earlier thread here.

 

http://www.canalworld.net/forums/index.php?showtopic=70353&hl=+cuthound%20+stirling%20+engine&page=3

 

Post #51& #56

 

ETA post numbers.

Do you have one? I have a wispergen in my boat it does 72 amp and produces heat for my central heating it at full bore use 3/4 litre of kero/diesel when the batteries are charged it cuts back to 1/3 litre of fuel per hour it works, its silent its very clean on emissions and has been low maint I only use it in the winter its on a timer so I wake up to hot rads and go home to hot rads so clearly it does work for the purpose it was designed for

 

Peter

[cuthound]

Do you have one? I have a wispergen in my boat it does 72 amp and produces heat for my central heating it at full bore use 3/4 litre of kero/diesel when the batteries are charged it cuts back to 1/3 litre of fuel per hour it works, its silent its very clean on emissions and has been low maint I only use it in the winter its on a timer so I wake up to hot rads and go home to hot rads so clearly it does work for the purpose it was designed for

 

Peter

 

Ño, but I was the Technical Manager for a company that installed 8 (35kW electrical, 250kW heat) in 2011 & 2012.

 

As stated they were unbelievably unreliable due to (in my opinion) being put onto the market before they were fully developed. On the rare occasions they ran properly, they worked well. However because of their unreliability the Danish manufacturer went bust, which in turn caused my employer to go bust.

 

The Whispergen has a much lower output, and that is probably why it is reliable. Different beast entirely.

[George94]

Do you have one? I have a wispergen in my boat it does 72 amp and produces heat for my central heating it at full bore use 3/4 litre of kero/diesel when the batteries are charged it cuts back to 1/3 litre of fuel per hour it works, its silent its very clean on emissions and has been low maint I only use it in the winter its on a timer so I wake up to hot rads and go home to hot rads so clearly it does work for the purpose it was designed for

 

Peter

 

The telling point here is that you only use it in winter, because that is when you can make use of all the heat.

 

I think the Whispergen is a great product, and I wish they still made them - I would buy one like a shot. But it is a heater that produces a small (but useful) amount of electricity. As a generator pure and simple, it doesn't make sense.

[IanD]

Do you have one? I have a wispergen in my boat it does 72 amp and produces heat for my central heating it at full bore use 3/4 litre of kero/diesel when the batteries are charged it cuts back to 1/3 litre of fuel per hour it works, its silent its very clean on emissions and has been low maint I only use it in the winter its on a timer so I wake up to hot rads and go home to hot rads so clearly it does work for the purpose it was designed for

 

Peter

Diesel (Beta 50): 0.2l/hp-h

Wren gas turbine: 1.4l/hp-h (7x higher than diesel)

Whispergen: 0.6l/hp-h (1kW output at 0.75l/h) (3x higher than diesel)

[peterboat]

Diesel (Beta 50): 0.2l/hp-h

Wren gas turbine: 1.4l/hp-h (7x higher than diesel)

Whispergen: 0.6l/hp-h (1kW output at 0.75l/h) (3x higher than diesel)

Its wispergen and whilst a generator might produce more electric it doesnt produce the heat I want also the wispergen will run on kero which is cheaper and cleaner than diesel. Also and this is important the wispergen is very quiet. the other plus for the wispergen is when the batteries are charged it automatically slows down and saves fuel. It can be on an auto system to charge the batteries stopping and starting as needed it is a clever device which does what it says on the fibreglass box.

 

 

Peter