The splintered pine pondered
A "perfect swamp cooler," as I used the phrase, would have RH and temp controls, which has nothing to do with how close it can cool air to the wet bulb temp. I was thinking a swamp cooler like that could achieve
the same performance as any indoor scheme...
But thinking further, that isn't true, for swamp coolers that don't recirculate indoor air. Swamp coolers with RH and temp controls may still be less efficient than indoor schemes for houses with natural air leakage, ie all houses :-)
For instance, in this case, the indoor scheme required 1360 cfm of exhaust air and 44 pounds per hour of water:"
As far as perfect controls, the outdoor system is simpler and
therefore superior. A thermostat turns it on, pressure relief gets rid
of the moisture. KISS baby.
Evaporative cooling has everything to do with a wet bulb temperature.
Until you understand this, you do not really know what the hell you are
talking about. Print off some posts and go see a PE friend or two.
When I first saw this thread, you cross posted to
"sci.engr.heat-vent-ac". You were going on about how some ozzies were
having wondrous results running an evaporative cooler that recirculated
air. Indoor cooler has a fan, powered exhaust. Two fans in the original
cross posted example. Go look at the indoor and outdoor wet bulbs in
that ozzie example, about the same
Recently you have morphed it back to your pathetic indoor scheme that
involves flooding the floor.
With the traditional outdoor evaporative cooler, the space is
pressurized. There is an air exchange between the home and the outside
and this exchange involves cool humid air (with repesct to the ambient)
migrating out of the home to the outside.
You are quite proud of your physics but do not pay much attention to
pressure differentials else you would not be suggesting to people to
pressurize an attic or an attached garage. See the problem with that
yet by the way? The garage idea is dangerous, a life safety issue.
An indoor evaporative cooler will be prone to natural air infiltration
until the exhaust fan runs. Under design conditions the exhaust will
run steady. The negative pressure caused by the exhaust will cause
outdoor air to transfer in at a much higher rate than it ever would
naturally.
The flooded floor will be prone to mold problems. There are several
steps involved to get this heat transfer and each step is an
inefficiency. You will use even more water and airflow than you
incorrectly calculate. A cool ceiling would be infinitely superior to a
flooded floor. But when you rethink the slab, think again that the
coldest you get ever get the slab would be the wet bulb temperature of
the room air.
I gave you an example of a northern home in a heating situation before.
Floor slab in contact with soil most likely 42F. Heat loss through the
slab 2 btu/hr per square foot and this slab will be significantly
cooler than anything flooding can do to it. But now with a warmer slab
you are going to transfer more heat per square foot out of the room.
Scheme is a dog pure and simple.
The pine splintered some more
... 100(Pw-Pa)/(105-65) = -1 (Bowen, 1926) makes the water vapor pressures Pw-Pa = 0.4 "Hg, and Pw = e^
(17.863-9621/(460+65)) = 0.6296, approximately, using a Clausius-Clapeyron approximation, so Pa = 0.2296,
and the absolute outdoor humidity ratio wo = 0.62198/(29.921/Pa-1) = 0.00481 pounds of water per pound of dry
air.
... (105-80)C+10K = 1000P makes P = 0.025C + 10 pounds per hour of water, since C cfm of airflow moves about
C Btu/h-F and evaporating each pound of water takes about 1000 Btu. With wi = 0.0120 (an efficient corner of
the ASHRAE 55-2004 comfort zone), P = 0.075x60C(wi-wo) = 0.03236C, since each cubic foot of air weighs about
0.075 pounds and there are 60 minutes each an hour (want to argue about that? :-) so C = 1360 cfm and P = 44,
ie we evaporate 5.28 gallons per hour of water."
So far you are dreaming that the flooded floor will approach the
performance of a typical swamp cooler on the roof with those numbers.
As I tried to explain to you the 1360 CFM and 44 pounds of water is
typical of an 80% effective swamp cooler. You are dreaming that it will
work as good, there are numerous other problems in the flooded floor
scheme that you will not acknowledge.
yet another splinter
Now suppose the house leaks 200 cfm of air (about average in the US.) In the indoor scheme, the fan would only move 1160 cfm, and the cooler might reduce its airflow to 1160 cfm (real vs inflated cooler cfm :-), so the cooler and the indoor scheme would have equivalent performance.
But what can the cooler do if the house leaks more air or we need less cooling? Suppose we only need 200 cfm of outdoor air? It can't reduce the airflow to zero and still evaporate water, so it will have to move excess outdoor air through the house and use excess water, ie the indoor scheme will use less air and water in this case.
For equivalent performance, it seems we also have to add a motorized bypass damper to the swamp cooler to
allow indoor air recirculation."
Lol Rube, it cycles off with the thermostat. Don't start pricing bypass
dampers or modualting exhaust fan controls at Grainger just yet, forget
buying a fanhandler
You run a 1360 CFM exhaust fan steady in a small home and that is going
to be your air exchange. Maybe some wind effect of from a tornando or a
hurricane will make a difference. :-)
Maybe don't cross post so much and spare your EIT ego a beating from
illiterate HVAC criminals
. We do this for a living and we are
responsible for advise we give and the things we do. You spew out crap
with no consequences.
The traditional swamp cooler will over power natural infiltration, you
do not comprehend this. An indoor cooler with an exhaust fan will have
a make up air rate far greater than 200 CFM from natural causes such as
wind effect.
Maybe look at what your fellow solar geeks at the Florida Solar Center
say about the effects of Space Pressurization.
http://www.fsec.ucf.edu/bldg/science/mold/index.htm