On 15 Feb 2016 at 12:15, Richard Aiken wrote:

> Except that - as several somebodies who know the actual math involved
> have pointed out repeatedly - simple water would work better as a
> heat sink, since it's denser (which is what you want in a heat sink)
> and MUCH less difficult to process/transport/manipulate than is
> liquid hydrogen.  

It's not merely that water is denser, it's that it has a higher heat
capacity (number of joules required to raise a kilo of it by one
degree C). Add in the heat of crystallization (amount of energy
required to change a kilo of ice to a kilo of liquid, both at the
melting temp) and heat of vaporization (energy required to change a
kilo of liquid at boiling point to a kilo of vapor at the same temp)
both of which *huge* for water, and there's damn little that would
work better. and none of the others are either common or easy to
handle.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com