On Thu, 12 Nov 2009 21:27:15 +0000 Andy Champ wrote :
If you have an internal combustion engine, especially one with a turbo-
or supercharger, hot inlet air reduces the mass of air available for
combustion. So the bang is smaller. Cooling the air wastes energy -
but the extra power is generally desirable (if you are a car salesman!).

It won't help us with a boiler, where 10% less output is probably not an
issue, but 10% less efficiency matters.

Nothing like 10% I think - gas delivers 10.8kW/m3. Specific heat of air is
1.25kJ/m3/K = 0.004kW/m3/K, so raising the air temp by 40C saves
0.016kW/m3. This needs to be multiplied by the air/gas ratio.

40 years since I did O-level physics so these numbers probably wrong!

--
Tony Bryer, Greentram: 'Software to build on' Melbourne, Australia
www.superbeam.co.uk www.superbeam.com www.greentram.com