----- Original Message ----- From: "Jed Rothwell" <[EMAIL PROTECTED]> To: <vortex-L@eskimo.com> Sent: Thursday, March 08, 2007 7:25 PM Subject: Re: [Vo]: Proof of capturing ambient temperature energy
> Michel Jullian wrote: > >>The highly OU commercial ambient air energy pumping devices I was >>talking about are those residential heating heat pumps we have been >>discussing in the 'loop closed' thread, they commonly reach COPs of >>4 (1000W out for 250W in, the excess coming from ambient air). > > I thought this thread was a joke. The 'loop closed' thread you mean? It was a joke indeed, I said so and I explained why the overall loop COP was necessarily sub unity. Still, these things have high COPs, much higher than what has been achieved by e.g. cold fusion, or even present hot fusion devices for that matter. > A heat pump is NOT over unity. I don't get it. You mean overunity doesn't mean a COP>1 !? Or that the coefficient of performance isn't the ratio of output to input energy? Or that COP is not a proper term for heat pumps? Or that heat pumps don't have COPS over unity? Or that it matters whether the excess energy comes from ambient air or from e.g. fusion inside the device? > Using old-fashioned terminology, a heat pump moves heat from a cold > "reservoir" to a hot one. When you drive a heat engine with the heat > from the hot reservoir, the heat engine produces less energy overall > than the heat pump consumed. > > The "COP" of 4 refers to the amount of heat energy moved versus the > amount expended by the machine, but you cannot move that same heat > back the other direction with a heat engine and get back 4 times > input, because the hot reservoir is only a little warmer than the > cold one, and Carnot efficiency is low. > > Let me give an imaginary example with round numbers. Suppose you live > in Florida where you need to heat a house only a little more than the > surroundings. You run a gasoline powered heat pump -- a very > efficient heat pump with a COP of 6. It converts 20% of the starting > energy into air conditioner power, which then moves 5 * 20% into the 6*20% you mean > house = 120% of the original fuel. > > You can burn 1000 joules worth of fuel in the house, or use the same > amount of fuel in the heat pump to move 1200 joules of heat from the > surroundings into the house. But, the temperature difference between > the house and the surrounding is 5 deg C (6 deg C with the heat > pump), and when you attach a heat pump to the house and let the heat heat engine you mean > flow through it, it is only 1% efficient, so the 1200 joules converts > to 12 joules of useful work. It is physically impossible for any heat > engine to convert the heat back into 1000 joules of work, or more. Sure, that's what I said in the 'loop closed thread'. So what? > If you only want to make the hot reservoir a little warmer than the > surroundings, a heat pump can achieve very high C.O.P.s of 10 or > more, but in no case can you reverse the process with a heat engine > and get more out than you put in. > > - Jed > All this is quite correct, except the typos I pointed out. Also a gasoline powered heat pump as in your example is not very energy efficient (overall COP 1.2 in your example of 1000J in, 1200J out for a 5°C difference), electrical ones have much better overall COPs (e.g. 250W in, 1000W out as I said, by consuming 250W from the mains you get the same heating power as a 1000W electrical heater, nothing magical though). Anyway, so what? I don't understand your objections. Or do you mean that your definition of overunity is in fact that the overall COP _with a hypothetical heat engine attached_ should be over unity? Honestly I really don't get it. Michel
