old man emu Posted May 12, 2020 Share Posted May 12, 2020 Isn't it against the law to have carnot knowledge? Only if its with an imbecile. 1 Link to comment Share on other sites More sharing options...
facthunter Posted May 12, 2020 Share Posted May 12, 2020 The higher the latent heat figure the Less efficiency. You generally don't recover it. If you do, entropy comes into play. Heat flow from high order to lower temps. It never flows the other way. Nev Link to comment Share on other sites More sharing options...
Geoff_H Posted May 12, 2020 Share Posted May 12, 2020 The higher the latent heat figure the Less efficiency. You generally don't recover it. If you do, entropy comes into play. Heat flow from high order to lower temps. It never flows the other way. Nev Heat will only flow from the hotter to the lower temperature is the Zero'th law of thermodynamics, they had already named law 1 and law 2 and then realised that heat flow was even more important so it got the Zero law. If you want the most efficiently then raise the temperature and pressure above the critical point. At this point water goes directly to steam. Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted May 12, 2020 Share Posted May 12, 2020 You guys make me think of the old steam Ghan. I reckon the efficiency was real low, what with expelling that steam all the time. But the fuel was cheap, so miles per dollar would be a better measure than miles per kilo of coal. My guess is that it would have done about 1 tenth of a mile per kilo of coal. Link to comment Share on other sites More sharing options...
turboplanner Posted May 12, 2020 Share Posted May 12, 2020 You guys make me think of the old steam Ghan. I reckon the efficiency was real low, what with expelling that steam all the time. But the fuel was cheap, so miles per dollar would be a better measure than miles per kilo of coal. My guess is that it would have done about 1 tenth of a mile per kilo of coal. Divide that up by the number of crew, passengers and freight units. Transfer that to a steam bike or car, and you'll have a comparison. Even better, compare one of the British locomotives that represented peak steam efficiency. 1 Link to comment Share on other sites More sharing options...
old man emu Posted May 12, 2020 Share Posted May 12, 2020 Are we going to set some parameters for this discussion? The first one would have to be Torque, then operating RPM. This would let us talk about Horsepower to take the discussion into the colloquial, which most people consider the best criteria for an engine. Following those, we would have to put a limit on the weight of the system. That would determine the number of cylinders our engine had. It would also affect the design - Two or Four Stroke. Then we would have to look at fluid supply and recovery. I'm assuming that we would use a compressed gas fuel. Link to comment Share on other sites More sharing options...
facthunter Posted May 12, 2020 Share Posted May 12, 2020 One of the things steam has is high torque at zero revs. A feature you don't need in an aero motor . For turbines you can have them for both , steam and IC, so compare like with like. If you don't deal with latent heat you won't find the problem, because THAT is the problem. You don't have to go any further. If you don't condense the steam you will carry more mass of water than coal. A Closed system has less boiler and corrosion issues. You can run pure water. Locomotive boilers are not very safe. If a tube lets Go you are in a dangerous position in the cabin..Nev Link to comment Share on other sites More sharing options...
onetrack Posted May 13, 2020 Share Posted May 13, 2020 (edited) Weight of the power unit is the biggest single over-riding factor in any of the smaller aircraft. On the basis that a steam engine needs an engine, a boiler, a condenser, piping, a water pump, plus associated valving and controls - and the overall weight starts to exceed any other currently available power unit. In addition, lubrication of a steam engine is not easy, because lubricant either needs to be added to the steam using a displacement lubricator, or a pressurised lube system with an oil pump and oil tank is required. There's also the high cost of manufacturing and certificating a boiler of adequate strength with minimum weight. High pressure is needed to develop maximum steam efficiency. You cannot afford to have doubtful high pressure components in a steam engine - the number of deaths, in the U.S. in particular, in the late 1800's to early 1900's, from boiler explosions, ran into the tens of thousands. Google "boiler explosion" and "images" and be prepared to be amazed at the constant destruction pictured from that era. Edited May 13, 2020 by onetrack 1 1 Link to comment Share on other sites More sharing options...
old man emu Posted May 13, 2020 Share Posted May 13, 2020 It's good that people are giving consideration to perceived drawbacks of using steam. The first step to solving a problem is to identify the problem. With due consideration to all other factors, I think the big killer of a steam engine in any for of transport is the cost of regular certification. Can you imagine the requirements CASA/RAAus would impose in relation to boiler certification? Then there would be the requirements demanded by the WH&S regulators. Finally, where are you going to find a qualified boiler certifier? I reckon that it is possible to make a steam engine system that could efficiently power an aircraft, but Regulation would make its use so expensive that it would cripple the economic value of the product. 1 1 Link to comment Share on other sites More sharing options...
Geoff_H Posted May 13, 2020 Share Posted May 13, 2020 A condenser running close to a vacuum adds 33% to the power. Sub critical maximum efficiency is approx 34%. Super critical is up to around 50%. Why not burn a liquid fuel, much lighter and easier to handle Link to comment Share on other sites More sharing options...
hihosland Posted May 13, 2020 Share Posted May 13, 2020 Mike Hughes did manage short term steam powered flight, Unfortunately ( at least for Hughes) on the first attempt he telescoped a few vertebrae and did not survive the second flight. 2 Link to comment Share on other sites More sharing options...
Yenn Posted May 13, 2020 Share Posted May 13, 2020 What is a four stroke steam engines cycle? I would assume that steam could be two stroke or one stroke, ie power on the up and the down stroke. 1 1 Link to comment Share on other sites More sharing options...
facthunter Posted May 13, 2020 Share Posted May 13, 2020 Steam is usually double acting and triple expansion. Like I said at the beginning. Just let the steam out the back as in post #111. Faster ships went to turbines. Nev 1 Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted May 13, 2020 Share Posted May 13, 2020 I just loved the old steam engines. So much power! the lovely look of all that heavy metal... and they didn't mind going through any amount of water. Well as long as there was a track left under the water. For years, they kept a steam engine at Alice Springs because the new diesel-electric locos could only take a few inches of water and once or twice the old steam engine rescued the Ghan. This was until the new line was built well away from the water. The old line followed the lowlands because the horses and camels used in building the track and later the steam engines all needed water. 1 Link to comment Share on other sites More sharing options...
Thruster88 Posted May 13, 2020 Share Posted May 13, 2020 Since diesel completely replaced steam in ships where size and wieght is not a factor I am guessing that a steam engines fuel efficiency is poor. The goggle has failed to enlighten me in this matter, so where would steam fit in this chart, worse than a 582? The following table takes values as an example for the specific fuel consumption of several types of engines. For specific engines values can and often do differ from the table values shown below. Energy efficiency is based on a lower heating value of 42.7 MJ/kg (84.3 g/(kW⋅h)) for diesel fuel and jet fuel, 43.9 MJ/kg (82 g/(kW⋅h)) for gasoline. [TABLE] [TR] [TH]kW[/TH][TH]hp[/TH][TH]Year[/TH][TH]Engine[/TH][TH]Type[/TH][TH]Application[/TH][TH]lb/(hp⋅h)[/TH][TH]g/(kW⋅h)[/TH][TH]efficiency[/TH] [/TR] [TR] [TD]48[/TD][TD]64[/TD][TD]1989[/TD][TD]Rotax 582[/TD][TD]gasoline, 2-stroke[/TD][TD]Aviation, Ultralight, Eurofly Fire Fox[/TD][TD]0.699[/TD][TD]425[1][/TD][TD]19.3%[/TD] [/TR] [TR] [TD]321[/TD][TD]431[/TD][TD]1987[/TD][TD]PW206B/B2[/TD][TD]turboshaft[/TD][TD]Helicopter, EC135[/TD][TD]0.553[/TD][TD]336[2][/TD][TD]24.4%[/TD] [/TR] [TR] [TD]427[/TD][TD]572[/TD][TD]1987[/TD][TD]PW207D[/TD][TD]turboshaft[/TD][TD]Helicopter, Bell 427[/TD][TD]0.537[/TD][TD]327[2][/TD][TD]25.1%[/TD] [/TR] [TR] [TD]500[/TD][TD]670[/TD][TD]1981[/TD][TD]Arrius 2B1/2B1A-1[/TD][TD]turboshaft[/TD][TD]Helicopter, EC135[/TD][TD]0.526[/TD][TD]320[2][/TD][TD]25.6%[/TD] [/TR] [TR] [TD]820[/TD][TD]1,100[/TD][TD]1960[/TD][TD]PT6C-67C[/TD][TD]turboshaft[/TD][TD]Helicopter, AW139[/TD][TD]0.490[/TD][TD]298[2][/TD][TD]27.5%[/TD] [/TR] [TR] [TD]958[/TD][TD]1,285[/TD][TD]1989[/TD][TD]MTR390[/TD][TD]turboshaft[/TD][TD]Helicopter, Tiger[/TD][TD]0.460[/TD][TD]280[2][/TD][TD]29.3%[/TD] [/TR] [TR] [TD]84.5[/TD][TD]113.3[/TD][TD]1996[/TD][TD]Rotax 914[/TD][TD]gasoline, turbo[/TD][TD]Aviation, Light-sport aircraft, WT9 Dynamic[/TD][TD]0.454[/TD][TD]276[3][/TD][TD]29.7%[/TD] [/TR] [TR] [TD]88[/TD][TD]118[/TD][TD]1942[/TD][TD]Lycoming O-235-L[/TD][TD]gasoline[/TD][TD]Aviation, General aviation, Cessna 152[/TD][TD]0.452[/TD][TD]275[4][/TD][TD]29.8%[/TD] [/TR] [TR] [TD]1,799[/TD][TD]2,412[/TD][TD]1984[/TD][TD]RTM322-01/9[/TD][TD]turboshaft[/TD][TD]Helicopter, NH90[/TD][TD]0.420[/TD][TD]255[2][/TD][TD]32.1%[/TD] [/TR] [TR] [TD]63[/TD][TD]84[/TD][TD]1991[/TD][TD]GM Saturn I4 engine[/TD][TD]gasoline[/TD][TD]Cars, Saturn S-Series[/TD][TD]0.411[/TD][TD]250[5][/TD][TD]32.5%[/TD] [/TR] [TR] [TD]150[/TD][TD]200[/TD][TD]2011[/TD][TD]Ford EcoBoost[/TD][TD]gasoline, turbo[/TD][TD]Cars, Ford[/TD][TD]0.403[/TD][TD]245[6][/TD][TD]33.5%[/TD] [/TR] [TR] [TD]300[/TD][TD]400[/TD][TD]1961[/TD][TD]Lycoming IO-720[/TD][TD]gasoline[/TD][TD]Aviation, General aviation, PAC Fletcher[/TD][TD]0.4[/TD][TD]243[7][/TD][TD]34.2%[/TD] [/TR] [TR] [TD]7,000[/TD][TD]9,400[/TD][TD]1986[/TD][TD]Rolls-Royce MT7[/TD][TD]gas turbine[/TD][TD]Hovercraft, SSC[/TD][TD]0.3998[/TD][TD]243.2[8][/TD][TD]34.7%[/TD] [/TR] [TR] [TD]2,000[/TD][TD]2,700[/TD][TD]1945[/TD][TD]Wright R-3350 Duplex-Cyclone[/TD][TD]gasoline, turbo-compound[/TD][TD]Aviation, Commercial aviation; B-29, Constellation, DC-7[/TD][TD]0.380[/TD][TD]231[9][/TD][TD]35.5%[/TD] [/TR] [TR] [TD]57[/TD][TD]76[/TD][TD]2003[/TD][TD]Toyota 1NZ-FXE[/TD][TD]gasoline[/TD][TD]Car, Toyota Prius[/TD][TD]0.370[/TD][TD]225[10][/TD][TD]36.4%[/TD] [/TR] [TR] [TD]550[/TD][TD]740[/TD][TD]1931[/TD][TD]Junkers Jumo 204[/TD][TD]diesel 2-stroke, turbo[/TD][TD]Aviation, Commercial aviation, Junkers Ju 86[/TD][TD]0.347[/TD][TD]211[11][/TD][TD]40%[/TD] [/TR] [TR] [TD]36,000[/TD][TD]48,000[/TD][TD]2002[/TD][TD]Rolls-Royce Marine Trent[/TD][TD]turboshaft[/TD][TD]Marine propulsion[/TD][TD]0.340[/TD][TD]207[12][/TD][TD]40.7%[/TD] [/TR] [TR] [TD]2,340[/TD][TD]3,140[/TD][TD]1949[/TD][TD]Napier Nomad[/TD][TD]Diesel-compound[/TD][TD]Concept Aircraft engine[/TD][TD]0.340[/TD][TD]207[13][/TD][TD]40.7%[/TD] [/TR] [TR] [TD]165[/TD][TD]221[/TD][TD]2000[/TD][TD]Volkswagen 3.3 V8 TDI[/TD][TD]Diesel[/TD][TD]Car, Audi A8[/TD][TD]0.337[/TD][TD]205[14][/TD][TD]41.1%[/TD] [/TR] [TR] [TD]2,013[/TD][TD]2,699[/TD][TD]1940[/TD][TD]Deutz DZ 710[/TD][TD]Diesel two stroke[/TD][TD]Concept Aircraft engine[/TD][TD]0.330[/TD][TD]201[15][/TD][TD]41.9%[/TD] [/TR] [TR] [TD]42,428[/TD][TD]56,897[/TD][TD]1993[/TD][TD]GE LM6000[/TD][TD]turboshaft[/TD][TD]Marine propulsion, Electricity generation[/TD][TD]0.329[/TD][TD]200.1[16][/TD][TD]42.1%[/TD] [/TR] [TR] [TD]130[/TD][TD]170[/TD][TD]2007[/TD][TD]BMW N47 2L[/TD][TD]Diesel[/TD][TD]Cars, BMW[/TD][TD]0.326[/TD][TD]198[17][/TD][TD]42.6%[/TD] [/TR] [TR] [TD]88[/TD][TD]118[/TD][TD]1990[/TD][TD]Audi 2.5L TDI[/TD][TD]Diesel[/TD][TD]Car, Audi 100[/TD][TD]0.326[/TD][TD]198[18][/TD][TD]42.6%[/TD] [/TR] [TR] [TD]620[/TD][TD]830[/TD][TD][/TD] [TD]Scania AB DC16 078A[/TD][TD]Diesel 4-stroke[/TD][TD]Electricity generation[/TD][TD]0.312[/TD][TD]190[19][/TD][TD]44.4%[/TD] [/TR] [TR] [TD]1,200[/TD][TD]1,600[/TD][TD]early 1990s[/TD][TD]Wärtsilä 6L20[/TD][TD]Diesel 4-stroke[/TD][TD]Marine propulsion[/TD][TD]0.311[/TD][TD]189.4[20][/TD][TD]44.5%[/TD] [/TR] [TR] [TD]3,600[/TD][TD]4,800[/TD][TD][/TD] [TD]MAN Diesel 6L32/44CR[/TD][TD]Diesel 4-stroke[/TD][TD]Marine propulsion, Electricity generation[/TD][TD]0.283[/TD][TD]172[21][/TD][TD]49%[/TD] [/TR] [TR] [TD]4,200[/TD][TD]5,600[/TD][TD]2015[/TD][TD]Wärtsilä W31[/TD][TD]Diesel 4-stroke[/TD][TD]Marine propulsion, Electricity generation[/TD][TD]0.271[/TD][TD]165[22][/TD][TD]51.1%[/TD] [/TR] [TR] [TD]34,320[/TD][TD]46,020[/TD][TD]1998[/TD][TD]Wärtsilä-Sulzer RTA96-C[/TD][TD]Diesel 2-stroke[/TD][TD]Marine propulsion, Electricity generation[/TD][TD]0.263[/TD][TD]160[23][/TD][TD]52.7%[/TD] [/TR] [TR] [TD]27,060[/TD][TD]36,290[/TD][TD][/TD] [TD]MAN Diesel S80ME-C9.4-TII[/TD][TD]Diesel 2-stroke[/TD][TD]Marine propulsion, Electricity generation[/TD][TD]0.254[/TD][TD]154.5[24][/TD][TD]54.6%[/TD] [/TR] [TR] [TD]34,350[/TD][TD]46,060[/TD][TD][/TD] [TD]MAN Diesel 12G95ME-C9[/TD][TD]Diesel 2-stroke[/TD][TD]Marine propulsion[/TD][TD]0.254[/TD][TD]154.5[25][/TD][TD]54.6%[/TD] [/TR] [TR] [TD]605,000[/TD][TD]811,000[/TD][TD]2016[/TD][TD]General Electric 9HA[/TD][TD]Combined cycle[/TD][TD]Electricity generation[/TD][TD]0.223[/TD][TD]135.5 (eq.)[/TD][TD]62.2%[26][/TD] [/TR] [/TABLE] 1 Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted May 13, 2020 Share Posted May 13, 2020 Wot no Jabiru! 1 Link to comment Share on other sites More sharing options...
Geoff_H Posted May 13, 2020 Share Posted May 13, 2020 A steam power station with sub critical point operation would be around 34% efficient. A supercritical would get to around 60%. Please note that the combined cycle efficiency uses a gas turbine with a class C or D design and the exhaust from the gas turbine makes steam that uses a steam turbine to augment the output. Class H gas turbine will have around 60%=efficiency itself Link to comment Share on other sites More sharing options...
Thruster88 Posted May 13, 2020 Share Posted May 13, 2020 A steam power station with sub critical point operation would be around 34% efficient. A supercritical would get to around 60%. Please note that the combined cycle efficiency uses a gas turbine with a class C or D design and the exhaust from the gas turbine makes steam that uses a steam turbine to augment the output. Class H gas turbine will have around 60%=efficiency itself How would a piston type steam engine compare in terms of shaft hp with diesel for efficiency? Link to comment Share on other sites More sharing options...
Geoff_H Posted May 13, 2020 Share Posted May 13, 2020 I don't know the horsepower of steam engine with the same displacement as a diesel, but it's output would depend upon the steam pressure. I would guess that the efficiency of the steam engine would be less than 5% if it was an open cycle and around 8% for a closed cycle. But so much depends upon the boiler. It's temperature and pressure delivered to the engine 1 1 Link to comment Share on other sites More sharing options...
old man emu Posted May 13, 2020 Share Posted May 13, 2020 Here's one to think about: 1 Link to comment Share on other sites More sharing options...
facthunter Posted May 13, 2020 Share Posted May 13, 2020 Superlongstroke Marine diesel would have to be close to the best About 76 R'sPer Minute, supercharged very high BMEP, runs on Bunker fuel .Nev Link to comment Share on other sites More sharing options...
Marty_d Posted May 13, 2020 Share Posted May 13, 2020 Mike Hughes did manage short term steam powered flight, Unfortunately ( at least for Hughes) on the first attempt he telescoped a few vertebrae and did not survive the second flight. [ATTACH type=full" alt="1589339658815.png]53165[/ATTACH] Didn't he make it to about 600 feet before reaching apex and popping the chute? (on the one that didn't kill him!) If he'd just asked to use an aircraft carrier's steam catapult and hooked up a small glider to it, he probably could have got higher with that launching him. If the wings stayed on. Link to comment Share on other sites More sharing options...
Geoff_H Posted May 13, 2020 Share Posted May 13, 2020 Superlongstroke Marine diesel would have to be close to the best About 76 R'sPer Minute, supercharged very high BMEP, runs on Bunker fuel .Nev Bunker C is solid at room temperature. A reasonably large heating system would required for the fuel tanks and feed system. You can walk on it and not leave an impression. Ships and power stations use it as it is very cheap. Link to comment Share on other sites More sharing options...
Geoff_H Posted May 14, 2020 Share Posted May 14, 2020 If I was doing a steam project I would use a vane motor for the propeller I would make the boiler the main item of concern. I also would make it closed loop. For the boiler would use very small bore high pressure tube because that is the lightest weight for the biggest surface area and power at using gasoline. I would definitely have a superheater in the boiler. Because it's a closed system I would need a condenser this would be some type of air condenser which is less efficient than a water condenser but that's all we have. Link to comment Share on other sites More sharing options...
spacesailor Posted May 14, 2020 Share Posted May 14, 2020 Fire tube boiler. Water tube boiler. Fire tube boiler needs a certified operator. A water tube only needs a trained operator. spacesailor Link to comment Share on other sites More sharing options...
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