On 23/08/2019 11:19, Spike wrote:
On 21/08/2019 13:48, Tim Streater wrote:
Andrew wrote:
On 21/08/2019 09:30, Tim Streater wrote:

Side note: towel rails should be white not chrome finish for best
radiation.

Matt black surely ?, but when draped with wet/damp towels only
conduction is relevant anyway ?

Black would look ugly and intrusive; the emissivity of a white finish
vs. black is small compared to how bad chrome is.

While it's a fact that metals have low emissivity, that's only true for
super-clean surfaces. It only takes 20 microns of any kind of oil,
finger grease, body fat, random airborne contaminants, etc, to raise the
emissivity significantly towards the 'black' end of the range - from
memory 0.2 for clean metals, 0.8 for the 20-micron contaminated surface.

It's why painted surfaces have high emissivity irrespective of the
colour, the radiation taking place more from the paint binder than the
pigment due to the '20 micron effect'.


It is a little known fact that the majority of heat generated by
'radiators' is not radiated.

It is convected.

It is another little known fact that heating things does not dry them.
It is heating the air moving past them so that it can carry away the
moisture, that dries them.

Now apply those facts to towel rails..




--
Climate Change: Socialism wearing a lab coat.