On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:

In article , Tim Streater
wrote:

One of the laws of thermodynamics IIRC - efficiency is related to the
difference between input and output temps - in degrees K, not C.

my elementary physics suggests that if you are only refering to a
temperature difference the answer is the same in °K and in °C.°

The main benefit of using deg K instead of Deg C is the complete and
utter absence of negative numbers by which to confuse the mathematics. :-)

It's true enough that as far as steam engines are concerned, this is
unlikely to effect calculations involving deg C, but there are other heat
engines designs based on fluids with much lower freezing and boiling
points than zero deg C (the triple point of water to within an accuracy
of one decimal place).

FFS Kelvins aren't degrees.

And it must be absolute temperature for the equations to work.

Just consider what the results would look like for Tin-Tout/Tout if Tout
was negative.

Andy