Re: Heating a City

On 2008-04-08, Charles Talleyrand <kitplane01@[EMAIL PROTECTED]
> wrote:
> Is that really true.  If I have a couple of hundred megawatts and I
> just want to heat a few square miles, that should be doable.

Without enclosing those few square miles, you'll need much, much more
than that.

For example, suppose there's a 15 m/s wind blowing.  You'll need to
replace heat lost in the air, probably to a height of a couple hundred
metres due to mixing and the natural tendency of warmer air to rise.
For an area with a diameter of 3 km (a very small city indeed), that's
a flow rate on the order of 10 Gg/s.  Multiplying by the temperature
rise (about 10 K) and heat capacity of air (about 1000 J/kg-K) yields
a power requirement of about 100 GW.

So a couple of hundred megawatts is less than 1% of the required
power.


- Tim