[TriLUG] OT: thermodynamics of A/C question

[Jeremy Portzer]

On 6/28/2012 2:55 AM, Joseph Mack NA3T wrote:
> On Wed, 27 Jun 2012, matt at noway2.thruhere.net wrote:
>
>> My coworker said that he has done that on occasion and he could
>> hear the difference in the motor as it caused the load to back off
>> substantially.
>
> so you should be able to tell straight away. Maybe I should go buy a 
> mist nozzle.
>
>> These next few days are going to be exceptionally hot (101-103F).
>
> glad it was cool enough to open up the house last night.
>
>> We were also talking about why more systems aren't water cooled.  We 
>> could see two problems with water/evaporative cooling.
>
> that's two different systems. I was talking about water cooling as in 
> a car radiator.
>
> Joe
>

But Joe, the condenser unit already has a "radiator" to cool the 
compressed freon: - heat sink, fins to transfer the heat to the air, and 
a large fan, just like in your car.  What's the benefit of an extra 
cycle of water in addition to that?   You'd need a heat exchanger 
between the freon loop and the water loop - for what purpose?  The fins 
and fan do an adequate job transferring the heat directly from the freon 
to the air without the additional complexity of a water loop.  
Ultimately the heat has to get into the air no matter how many 
intervening cycles you add - unless you are talking geothermal systems 
or something else fundamentally different.

And of course we've already discussed the cooling tower systems that 
commercial A/C's use and the pros/cons of those:  they aren't 
cost-effective for small-scale systems.

To get back to the spirit of the thread however, another easy to take 
action you can do to improve your condenser's efficiency is to simply 
clean the fins, so that they can transfer heat between the freon and air 
more efficiently.  See for example this link: 
http://blog.srmi.biz/energy-saving-tips/residential-air-conditioning-aircon-ac/cleaning-condenser-coils/ 
.

--Jeremy