Steam Powered BMW

[henk4]

not being an expert at all, I am still surprised that the triple expansion engine here is heralded as very efficient. I know that in shipbuilding the last ones of these were applied in the fifties, before being replaced by diesel engines or steam turbines for the larger ships. How would that have come about then.

[henk4]

Edit:also it seems that Henk4's quote that the steam couldn't give the motor a 15% increase in milage and Power seems to be wrong as BWM claims that they get both!!! yeah it is looking better already!

It was a quotation from the German car magazine Auto Motor und Sport, where they say that at the prototype set up 14 additional BHP and 20 additional NM of torque were realised. "Also realisable would be a reduction in fuel consumption of about 1.5 litre". "With the system either the performance of the engine can go up or the fuel consumption can go down"

[Matra et Alpine]

not being an expert at all, I am still surprised that the triple expansion engine here is heralded as very efficient. I know that in shipbuilding the last ones of these were applied in the fifties, before being replaced by diesel engines or steam turbines for the larger ships. How would that have come about then.

Because steam engines used water AND fuel and you can't take sea water untreated because of the impurities and salts.
Steam engines for their power - esp triple expansion - are HUGE. pwoer comes from stroke, not revs
Steam needs to be "built up" to be usable and that takes large boilers.

Modern steam "turbine" engines have been used in LNG tankers for safety ( dont' know how efficient a turbine is compared to triple expansion tho }

Advances in electric motors has taken propulsion in a different direction.

The problem with steam is the heat generation side of the equation. The triple expansion is an efficient extraction. So when the heat is there anyway, using steam makes sense. If you have to generate the steam then there are better wasys with less energy losses to get the final power out. ( so burning diesel to heat water to drive a piston has one extra energy conversion with it's associated losses than burning it straight in a decent diesel engine )

[hightower99]

Then I take it you work some where with some kind of thermal test apparatus? How exactly do you go about to determine all the losses?

I suspect the exhaust is easy, assume ambient in and then measure temperature and pressure at the exhaust valve will get you in the ball park. Or perhaps a better measure is to use the static pressure and volumetric flow rate? Also, how is the un-burnt fuel accounted for?

For the coolant and oil, again measure the initial and final temperatures and pressures. Is the heat stored in the block significant at all? Also, to measure the heat lost to ambient does the test apparatus need to be in a thermal chamber?

Well I won't go into details too much but basically when I want to measure and engine (I don't just measure effeciency or losses) then I use a bunch of things. first I normally take the motor out of whatever vehicle it is in and stick it in an insulated control room then attache an exaust analyser that takes care of alot of things (final exaust temp. exaust content. volume of exaust.and pressure) I also attache a laser reader and a toothed sprocket to the crankshaft. (that tells me exact RPM and the position of the crankshaft at any given time.) I also put thermometers and pressure sensore in several places in the intake and exaust and I put a pair of special spacial thermometers and a pressure sensor in one of the cylinders (one near the spark plug and one on the exaust valve.) the last 2 thermometers can give me a realtime 3D image of the temperatures in the cylinder. The radiator is put into a small control room where I can meassure it and I normally put 3-10 thermometers pressure sensors and flow meters in the block normally around a single cylinder. I do not own much of this equipment as I am not the richest person I loan it from a close group of friends that are helping me out. I am hoping to get my hands on an ultrasonic density sensor and a special type of 3D flowmeter so I can start making better maps of engine flow in the cylinder...

not being an expert at all, I am still surprised that the triple expansion engine here is heralded as very efficient. I know that in shipbuilding the last ones of these were applied in the fifties, before being replaced by diesel engines or steam turbines for the larger ships. How would that have come about then.

steam engines are relatively effecient but a good 2 stroke diesel is better not to mention more powerfull and cheaper to run. What killed steam engines is that they do not last long without constant care. also the fact of there low specific power output compared to their size.

[henk4]

Because steam engines used water AND fuel and you can't take sea water untreated because of the impurities and salts.
Steam engines for their power - esp triple expansion - are HUGE. pwoer comes from stroke, not revs
Steam needs to be "built up" to be usable and that takes large boilers.

Modern steam "turbine" engines have been used in LNG tankers for safety ( dont' know how efficient a turbine is compared to triple expansion tho }

Advances in electric motors has taken propulsion in a different direction.

The problem with steam is the heat generation side of the equation. The triple expansion is an efficient extraction. So when the heat is there anyway, using steam makes sense. If you have to generate the steam then there are better wasys with less energy losses to get the final power out. ( so burning diesel to heat water to drive a piston has one extra energy conversion with it's associated losses than burning it straight in a decent diesel engine )

That makes sense, so if the heat is there the TE engine can run efficiently.

BTW, LNG tankers use steam turbines (and are the last class of merchant ships to do so) because the boil-off of the cargo can be used as fuel, it has nothing to do with safety. In spite of this there are some LNG ships now that run a diesel engine, but it is not yet widespread.

[Matra et Alpine]

BTW, LNG tankers use steam turbines (and are the last class of merchant ships to do so) because the boil-off of the cargo can be used as fuel, it has nothing to do with safety. In spite of this there are some LNG ships now that run a diesel engine, but it is not yet widespread.

aha, right, that makes sense ( as did the safety angle when I was todl that )
So I'm guessing that because of the variability of the "boil off" that using it in an IC engine would be difficult ?

[henk4]

aha, right, that makes sense ( as did the safety angle when I was todl that )
So I'm guessing that because of the variability of the "boil off" that using it in an IC engine would be difficult ?

no it is more simple. The boil-off is freely available fuel. Heavy Fuel Oil will cost about 250-280 US$ per ton and these ships may used between 120-140 tons per day of that......

http://www.bunkerworld.com/index_fs.html

[Matra et Alpine]

no it is more simple. The boil-off is freely available fuel. Heavy Fuel Oil will cost about 250-280 US$ per ton and these ships may used between 120-140 tons per day of that......

http://www.bunkerworld.com/index_fs.html

Sorry Pieter, I was meaning the reason for going steam turbine rather than burning it directly in an otto cycle engine.

It makes LOTS of sense to burn the fuel that you're carrying !

[85RX7]

Seams like WAY to much complication... well, its not really complicated, but u know what i meen... Would probably cost heaps to fix if it goes wrong, that alone would outweigh its ecomomy saving atributes.

[Matra et Alpine]

Seams like WAY to much complication... well, its not really complicated, but u know what i meen... Would probably cost heaps to fix if it goes wrong, that alone would outweigh its ecomomy saving atributes.

not sure why it should be complicated to fix as it's fairly simple.
BUT if you use 15% less fuel then for someone doing 20,000 miles a year you could afford to pay to have an ex stem train engineer sit in the back with you ( well nto quite, but any bills become less significant )

[Alastor]

I put a pair of special spacial thermometers and a pressure sensor in one of the cylinders (one near the spark plug and one on the exaust valve.) the last 2 thermometers can give me a realtime 3D image of the temperatures in the cylinder

Do you still have to drill holes in the block these measurements? What kind of sensors are you using, thermal couples and piezoelectric pressure sensors? Also, this might be a software vendor question but do you know how the 3D image is generated from just two points?

[henk4]

steam engines are relatively effecient but a good 2 stroke diesel is better not to mention more powerfull and cheaper to run. What killed steam engines is that they do not last long without constant care. also the fact of there low specific power output compared to their size.

Thanks, that confirmed what I thought, hence my surprise about the sudden praise for the TE steam engine.

[hightower99]

Do you still have to drill holes in the block these measurements? What kind of sensors are you using, thermal couples and piezoelectric pressure sensors? Also, this might be a software vendor question but do you know how the 3D image is generated from just two points?

I only have to drill holes in the intake and exaust systems but I can fix those for the cooling system and cylinder sensors I just take the engine apart and put them in.

I use some very nice thermal couples with ceramic bodys that will measure between 10 and 900C and I use piezoelectric pressure sensors the temp. sensors I use in the cylinder use phased infrared to take the 3D pictures (they give me 100 pictures of the whole cylinder every revolution up to 12000rpm but for the smaller engines I go down to 45 pictures for every rev. up to 25000rpm)
I am not sure how they get a 3D image but it seems to work.