Am 08.12.2011 21:31, schrieb Jed Rothwell:
Peter Heckert<peter.heck...@arcor.de> wrote:
Can you suggest a way to deliberately introduce such a small gap? Perhaps
with a thin piece of paper instead of an air gap?
A thin piece of plastics. This is also good for electrical isolation.
Like Saran wrap? (What you wrap sandwiches with.)
IDont know. The thermoelement must not make a hole into it.
When I measure electronic PCB's then I have sometimes to avoid, that the
thermoelement makes a shortage.
I cover it with a thin piece of silicon hose and apply a thermal
isolation. This works. Because the wires of the element also conduct
heat to the ambient, the isolation must cover some cm of the wire.
Of course, I dont do precision measurements. An error of 5 degrees would
not hurt much if the semiconductor has 100°.
We have a thermal security headroom of 25-50% under worst case conditions.
I know, what happens when the thermoelement has good or has bad contact,
and I know if I need additional isolation or not.
So you need not to do this experiment for me. I do not measure
waterpipes, but semiconductors, but the problem is the same.
I will try it on a copper pipe.
Your other assertions about bubbles of air in the pipe are untrue. The
metal of a steel or copper pipe averages out the temperature quite nicely.Dont
know
Yes, this is true. And if there is another heat source nearby, the pipe
will average this also ;-)
Nope. Not upstream or downstream very far. The air trapped in the pipe has
only a tiny thermal mass and it is the same temperature as the water so it
cannot affect things. In an axial area whole pipe is the same temperature,
even if there is air in part of it. That is what you see with Miles'
calorimeter, which is essentially a copper pipe open at the top. Fig. 4, p.
55:
http://lenr-canr.org/acrobat/MilesManomalousea.pdf
If you measure the temperature of a pipe with a great deal of water flowing
through it a short distance from a hot boiler, the water temperature
predominates.
I expect that Miles and others had installed the thermoelement in an
equilibrium place without heatgradient as required.
He installed several thermocouples at various locations in the copper
sheath. They all registered the same temperature to better than 0.01°C as I
recall.
Then there was no gradient. This is fine. If you heat one end of the
pipe and cool the other end, then you get a gradient and another
temperature at each location. A water flow would partially smear this
gradient, but if you have air in the pipe, the gradient will increase.
