Yes, it's known as the Carnot Efficiency. Heat engines CAN, in fact be much more efficient than 30%, since the Carnot efficiency depends on the ratio of the hotside to coldside. So for a heat engine operating between the temperatures of, say, 1000K and 10K, the maximum efficiency would be: efficiency = 1-Tc/Th = 1 - 10/1000 = 0.99 The problem is of course with maintaining these temperature differentials. Heat engine efficiency is in fact limited by materials properties. Typical cast iron blocks operate on the order of Tc = 100C, Th = 300C, giving a typical maximum efficiency of n = 1 - 373/573 = 0.35 Note that this Carnot efficiency is also changed by the outside temperature, so driving your car in the cold is more efficient than driving it in the heat. The mechanical linkages are relatively efficient, so actual engine efficiencies are around the 30% mark. So in fact, a fuel burning engine COULD be the energy of the future, but only if we find a new material that can withstand thousands of degrees! ----- Original Message ----- From: "Dominic Stratten" To: Sent: Saturday, April 24, 2004 4:07 AM Subject: Re: [OT]: Superb low temperature differential Stirling Engine > Taht's all bullshit... NO heat - force coupling engine can reach more > efficiency than 30%... May be they meant 90% of this maximum 30% > > At last, no fuel burning engine can be the energy generator of the future! > > > I do not belive the 90 percent efficiency claimed by them. It cannot be > > that good, due to the fact that there has to be major leakage (heat) > > between the hot side and the cold side of the piston. Even if the 'block' > > is plastic, there will still be a major heat loss. A burner (heat source) > > can be 90 percent efficient, but any moving parts are going to shoot their > > claimed efficiency specs down. If the efficiency was that good, they would > > be all over the place, especially in off the grid and isolated locations. > > > > Heat (as a byproduct) can be used to make cold air as well-so the unit > > could heat in winter and cool in summer. > > > > Flame suit on, fire away. > > > > Art > > > > At 04:34 PM 4/6/04, you wrote: > > >http://www.whispergen.com/ > > >Trials appear to be underway but I haven'r heard much about them for a > > > year or so. > > >Richard P > > > > > > > > > > > > > > > > > >Do you have som epointer for more info about "Whispergen"? > > > > > >/Ake > > > > > >-----Ursprungligt meddelande----- > > >Fren: pic microcontroller discussion list > > >[mailto:PICLIST@MITVMA.MIT.EDU]Fvr Richard.Prosser@POWERWARE.COM > > >Skickat: den 6 april 2004 22:07 > > >Till: PICLIST@MITVMA.MIT.EDU > > >Dmne: [OT:] Superb low temperature differential Stirling Engine > > > > > > > > >[Topic Added] > > >I think this is the philosophy behind the "Whispergen" stirling > > >engines. - > > >Electricity is produced as a by-product of home heating. > > >RP > > > > > > > > > > > >Sorry 137 KWh a day is the correct value. > > > > > >-----Ursprungligt meddelande----- > > >Fren: pic microcontroller discussion list > > >[mailto:PICLIST@MITVMA.MIT.EDU]Fvr Ake Hedman > > >Skickat: den 6 april 2004 11:02 > > >Till: PICLIST@MITVMA.MIT.EDU > > >Dmne: SV: SV: ] Superb low temperature differential Stirling Engine > > > > > > > > >But if you use a higher temp difference. > > > > > >In my case I warm the house with pellets and say I have a stirling > > >engine in a pre stage to my heater. pellets burn with a temp around 1200 > > >C > > > > > >1200 + 273 - 300 / 1475 = 79% 1/3 => 27% This goes to the electric > > >generator. > > > > > >I guess the losses are in heat so it can be used it to warm the house. > > > > > >I use about 1000 kg of pellets a week for warming in the winter ( big > > >house ). The total energy used a day is thus 1000 * 4.8kWh = 4800 KWh > > >Say I have 20% efficiency for the electivity generator I can take out > > >960 KWh a day in electric energy!!! and have the rest left to warm the > > >house. > > > > > >Do I have a fault in my thinking here? > > > > > > > > > > > > > > > > > > > > > > > >-- > > >http://www.piclist.com hint: PICList Posts must start with ONE topic: > > >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > >-- > > >http://www.piclist.com hint: PICList Posts must start with ONE topic: > > >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > > > > > > > >-- > > >http://www.piclist.com hint: PICList Posts must start with ONE topic: > > >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! 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