mcovingt@athena.cs.uga.edu ( Michael A. Covington) (12/11/90)
In article <2533@mentor.cc.purdue.edu> lairdkb@mentor.cc.purdue.edu (Kyler Laird) writes: >I apparently don't know enough about Plasma Cutters - Sears sells some >units that operate on 19 amps, yet produce 22 amps. > >Wow! Once ya get one started can it be connected to itself and used to power >a light bulb with the excess? > I presume those amps are at different voltages. A transformer (or any of several other devices) lets you trade volts for amps. You could put in 120 V at 1 A and get out 1 V at 120 A if the transformer were perfectly efficient. Total rate of energy consumption is measured in Watts = Volts x Amps.
dag@hp-lsd.COS.HP.COM (David Geiser) (12/13/90)
Check for neutrons.
tgg@otter.hpl.hp.com (Tom Gardner) (12/14/90)
Don't forget, you can have machines that you supply with, say, 1kW of electricity and which put >1kW of heat into your room. The _useful_ efficiency is thus >100%. N.B. no, this is in no way a perpetual motion machine, and it does not break any of the laws of thermodynmaics.
myers@hpfcdj.HP.COM (Bob Myers) (12/19/90)
>Don't forget, you can have machines that you supply with, say, 1kW of >electricity and which put >1kW of heat into your room. The _useful_ >efficiency is thus >100%. OK, Tom, taking as implied that the 1kW of electricity is the only source of power for the machine in question, exactly how is this done? Bob "Inquiring minds would like to know!" M.
tgg@otter.hpl.hp.com (Tom Gardner) (12/20/90)
|OK, Tom, taking as implied that the 1kW of electricity is the only source |of power for the machine in question, exactly how is this done? Hint: you almost certainly have one of these machine in your house, it's just that you don't use it in the "correct mode" to get >100% efficiency. Oh yes, the variant in question is available commercially.
mcovingt@athena.cs.uga.edu (Michael A. Covington) (12/22/90)
In article <1770028@otter.hpl.hp.com> tgg@otter.hpl.hp.com (Tom Gardner) writes: >|OK, Tom, taking as implied that the 1kW of electricity is the only source >|of power for the machine in question, exactly how is this done? > >Hint: you almost certainly have one of these machine in your house, it's just >that you don't use it in the "correct mode" to get >100% efficiency. > >Oh yes, the variant in question is available commercially. Heat pump? (Converting electricity to heat and also pumping heat in from the outside?)
rwa@cs.athabascau.ca (Ross Alexander) (12/25/90)
tgg@otter.hpl.hp.com (Tom Gardner) writes: >|OK, Tom, taking as implied that the 1kW of electricity is the only source >|of power for the machine in question, exactly how is this done? >Hint: you almost certainly have one of these machine in your house, it's just >that you don't use it in the "correct mode" to get >100% efficiency. >Oh yes, the variant in question is available commercially. Heat exchanger run as a furnace. Any other questions ?? -- -- Ross Alexander rwa@cs.athabascau.ca (403) 675 6311 ve6pdq
koziarz@halibut.nosc.mil (Walter A. Koziarz) (12/27/90)
In article <17660134@hpfcdj.HP.COM> myers@hpfcdj.HP.COM (Bob Myers) writes: >someone (must be named 'Tom') wrote: >>Don't forget, you can have machines that you supply with, say, 1kW of >>electricity and which put >1kW of heat into your room. The _useful_ >>efficiency is thus >100%. > >OK, Tom, taking as implied that the 1kW of electricity is the only source >of power for the machine in question, exactly how is this done? > Not difficult, really, note the '_useful_' qualifier (I generally use _effective_ in the same context). Here's an example (with which I am *very* familiar :-): Ground-coupled heat-pump -- mine has a coefficient of performance (COP) of 3.20; this means that 3.2 watts of heat energy is delivered to my house for every watt of electric power supplied. Hence: 320% EFFECTIVE Efficiency. You will quickly note that I weasel-worded my reply, you don't get 'something for nothing'; the heatpump extracts heat from the ground via a normal refrigeration cycle and the electric power is *NOT* the only energy input. But as far as the dollars are concerned, it's 320% efficient. Walt K.
myers@hpfcdj.HP.COM (Bob Myers) (01/03/91)
OK, OK, OK......I have been reminded of the existence of heat pumps sufficiently, now, and apologize for not realizing that this was the beast in question in the first place. Would everyone PLEASE stop sending e-mail? Bob "Put your brain in neutral for ONE MINUTE, and see what it gets you...:-)) M.
alien@hpdmd48.boi.hp.com (Tom von Alten) (01/09/91)
But the prize for best response goes to dag@hp-lsd.COS.HP.COM (David Geiser) for his "Check for neutrons."