In article
<566fdcec-2673-4497-bac7-d6824bbdcbc6@[EMAIL PROTECTED]
>,
dwight.thieme@[EMAIL PROTECTED]
<dwight.thieme@[EMAIL PROTECTED]
> wrote:
>
>I'm guessing that what is _meant_, rather than what was putatively
>_said_ was that of all the energy theoretically available, this device
>can recover 60%. So if you're talking about, say, 500 K and 300 K,
>you're talking about 60% of 40% or 24% overall efficiency. In the
>context of the advertised claims, this sounds reasonable.
Most solid state devices begin to lose efficiency and operate
differently as they heat up; one that operated at 300K *and* at
500K sounds hard to believe. I suppose you could build some clever
device of layered materials where one part of it doesn't even
start to work until it reaches at least 400K. But I have a hard
time believing this story without specifics.
BTW, some photovoltaics that work in the IR can be used as heat
engines of a sort; you keep the PV itself cool, while it receives
radiation from a black body a short distance away, preferably
across a vacuum gap. I seem to remember this being promoted as
a sort of emergency generator with no moving parts that could be
stored and neglected for long periods of time before suddenly
being needed.
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