Re: The chilling truth about cold horsepower

[stevecj at mail_utexas.edu]

Hi all,

Been lurking for a while, and thought I might try my hand at posting.

Scott H said:

>For example a 610 watt air conditioner is rated for 6000
>BTU/hr cooling capacity.  610 watts=2077 BTU/hr yields 6000
>BTU/hr cooling capacity.  Does this not seem odd?

>There is something I am obviously missing here, but I'll be
>darned if I can figure it out, so far. I'm checking this
>further.  I'll let you know what I find out.

There is another term you might want to consider called the "Coefficient of 
Performance" (or COP).  COP is used as a measure of efficiency of a 
refrigeration system.  It is defined as the cooling ability of the system over 
the power input to the system.  Because refrigerators, chillers, and air 
conditioners only move heat from one location to another it is possible to move 
an amount of thermal energy that is greater than the amount of work the pump or 
motor puts into the system.  It turns out that for air conditioners, typical 
values for the COP are somewhere around 2-3 or so (as memory serves).  

So, in your example above, the COP of the system would be (6000 BTU cooling)/
(2077 BTU power input) = 2.89.  As I recall, a COP in this range is not 
atypical.  Hope this helps.

Steve