On Feb 28, 11:49=A0am, IsaacKuo <mech...@[EMAIL PROTECTED]
> wrote:
> On Feb 28, 8:57=A0am, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> > On Feb 26, 2:02=A0pm, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> > > On Feb 26, 11:42 am, IsaacKuo <mech...@[EMAIL PROTECTED]
> wrote:
> > > > On Feb 26, 9:55 am, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> > > > > On Feb 25, 4:29 pm, IsaacKuo <mech...@[EMAIL PROTECTED]
> wrote:
> > > > > > On Feb 25, 2:14 pm, CharlesRCap...@[EMAIL PROTECTED]
wrote:
> > > All of these values could be off by huge amounts.
> > I found that the numbers I was using lead to a perpetual motion
> > machine. I looked around a bit and adjusted the compression factor to
> > 1.416 and the draw factor to 0.25. This leads to more satisfactory
> > numbers (i.e. I believe I'm going in the right direction, which is
> > less efficiency) =A0but they still amount to little more than wild
> > guesses.
>
> I think you're getting bogged down in the details of the
> middle steps, while it may be easier and less mistake-prone
> to analyze the thermodynamics of just the front end and
> tail end--the reactor heat source and the radiator(s).
>
> Your maximum potential efficiency is 1-Tcold/Thot,
> so start with your reactor temperature for Thot and
> your desired radiator temperature for Tcold. =A0For example,
> you could have Thot be 1400K (melting point of Uranium),
> and Tcold be 50K. =A0That leads to a maximum efficiency
> of 96.4%.
Thank you very much for that well reasoned and succinctly described
explanation. I am quite grateful for the time that you have spent
crafting it. Despite the simplicity of the mathematics involved it
taught me some very fundamental things about thermodynamics that will
be very helpful in understanding where my design is flawed, and boy it
is flawed. =3D)
You are absolutely correct, stepping back and looking at the big
picture helps immensely. Even with perfect efficiency (which the
Helium Turbine comes really close to) the maximum efficiency should be
no more than 86.5% from 1123K to ~150K while the design I put forth
has nearly 99% efficiency.
The deal breaker that you indicate (the huge radiator) is where I
would still disagree. The system rejects its waste heat into a ~150K
helium reservoir (mainly because from what I can gather the efficiency
of the electrothermals really starts to bottom out at 150K) so we have
the low point there.
The difference that I'd like to go with is that there is no reason I
can't take the heat that is radiated into the ~150K reservoir and then
compress it though a series of compressor/intercoolers until it is at
a high enough temperature to be rejected from a reasonable sized
radiator. The issue would be if the cost in waste heat and electrical
power would be too high to make that practical.
Your lesson in thermodynamics has given me a lot to think about, and I
thank you again for taking the time to explain this to me. (I'd like
to take some courses in physics beyond Physics 101 that I took 13
years ago, but I'd have to enroll and be accepted into the local state
university to take any. The other local colleges I attend are more
geared towards career type education even if in theory the degrees
they offer are just as good. And when I think about it, where would I
find the time?)
|
