digging around i found reference to interior cooling systems used prioer to about 1930 and came across
a reference and basic description of the operation of what was known as "tower and coil" cooling
the cooling tower was used to remove heat from the return water , the cooled water was pumped into
what at the time was typically truck radiators inside the space to be cooled and fan move the hot interior
air through these radiators.
the radiators took heat from the interior air thu cooling the space, the hot water coming off these radiators
was returned to the cooling tower where the circuit is completed and the process starts over.
in hot dry desert southwest these systems apparently worked amazingly well, keeping the interior temps
down to very bearable limits even while over 100F outside, the inside could be down well into the 70's F range.
if anyone has any info on these systems, or any book titles, links or anything let me know, as i am very interested
in cooling systems that use the cooling tower methods.
bob g
I would imagine the cooling tower had water sprayed on/in it. I don't see 70F from 100F ambient without some evaporation. Basically a swamp cooler without the added humidity... Then you get the associated scale and corrosion associated with water chemistry/minerals.
yes it was an evaporative process
and the water that made the loop form the radiators inside went into a loop in the bottom of the tower, to reject its heat
and then it would be pumped to the top of the tower and sprayed down into the tower over what was probably at the time
excelsior (wood fiber mats) much like a water cooler, but as you state without the added humidity in the house.
i would suspect that annually there would have to be some maintenance, the make up water would likely need to be demineralized
or use rain water, otherwise some sort of acid would have to be ran through the tower to clear the scale , followed by neutralize
and flush.
there is another system, that i came across that was really fascinating basically two units built into one housing
wherein one section was a water cooler, and the cooled water was then fed to the other section which had the heat
exchanger and air handling fan to duct in inside air where the heat was removed and cool water returned.
it used a single motor with double shafts and double squirrel cage fans, one for the cooler side, one for the air handler side.
that system looked as though it would do much the same as a cooling tower/coil unit, but do it in a smaller more compact unit.
my thinking is this, if such a unit could take a home from say 100F, down to even 85 degree's economically, then a standard airconditioner
system would have much less work to do taking the room down from 85 to 70 degree's.
from what i have read many of those systems were able to keep the space cooled down into the 70's, so even if it got it down to 79F
a relatively small A/C could then be used to knock down the last 7 or 8 degrees.
it is reported that these systems fell out of favor as electricity became more widely available and the new freon/compressor A/C came available
electricity was so cheap and the cost of a compressor unit although expensive was far less work to keep operational, they didn't need the tower
serviced or have connection to a good source of water.
since about 1985 the use of some of these old technologies have started to catch the eye on larger installations, most especially because that is where cooling towers are commonplace and fairly well understood.
for me i am interested in the design considerations and how they scale to smaller sq/ft buildings.
i know from experience a building with enough thermal mass that is cooled to around 65F overnight will manage to temper the interior temps through the heat of the next day, allowing interior temps to remain below 80F even though it can be over 100F outside. therefore an understanding of how towers are designed, would allow a source of cooling for the thermal mass below that of the overnight average temperatures for the area of operation. from what i gather it is not difficult to get a water temp 10 degrees below ambient having gone through
a tower, and that would assure the interior thermal mass could be even cooler to start the next day with.
i am very interested
bob g
That type of cooling for human consumption has some problems. Do a search on "Legionnaire's disease" It relates to respiratory infections that led to a bunch of fatalities at a convention and the source was eventually traced to the air conditioning. There are also cautions on contamination growing in hot water tanks where the temperature is held low to save standing heat loss.
No doubt that some kind of bio lethal chemical could be maintained that could keep the ickies from breeding but I am not sure what it would be. I have seen some treatment injection systems on industrial cooling towers but that was just in passing. Seemed like an alcohol odor but that might have been as a wetting agent or off the breath of some of my buddies, Lol!
Legionare's disease was caused by the failure of the maintenance company in the affected building to properly maintain the air conditioning system. the drain pans in the a/c systems were not cleaned properly allowing condensate water to stand in the pans, with the air that blows into the air conditioned space, blowing across the contaminated water, picking up the microbes & blowing them into the air in the building. Having the drains cleared to allow the condensate water to drain would have eliminated the problem, but now days they also use a small tablet, enclosed in a plastic pack , that slowly dissolves & kills the microbes. Can't remember what the chamical is, likely a form of solid chlorine bleach. In Bob's scenario I don't see this as a problem since thier should be very little, if any condensate to collect. And if thier is, the little tablets are really cheap. The water in the cooling tower will need to be treated to keep corrosion down but with the right test kit & chemicals it's easy to do.
Scott R.
A little copper sulfate would kill the bugs wouldn't it? I don't think it's terribly corrosive, could be wrong.
Ron
RERead lowspeedlife's contribution.
And that was the point of using the cooling tower is to keep the wet of the evap/cooling tower outside. Any fancoil unit inside, that moist room air circulates thru for cooling, will condense moisture out of the air. Just like the evap in any A/C system does. This condensate must be dealt with, just like in any A/C system..
I see from re reading Bobs post that the heat exchangers should isolate the air exposed to cooling water. The less you have to treat the water, the less problem there is with corrosion and the less you have to worry about electrolysis or scale . No question the air moving through a water fall is good heat sink but what is the cost / benefit compared to using the earth mass via under ground piping which can be used the other direction to supply heat in winter.
It seems to me that the condensation would take place in the cooling area where there aren't people. People are in the warming area where the heat is being transfer from. Nope, that's wrong. Obviously its a little fuzzy to me. The part that isn't stated yet but jumps out at me is the impact of accelerated processes brought on by the introduction of compression in modern refrigeration units.
Here's my ignorant question for this thread. Does the heat migrate or does the cool migrate?
Casey
Here I think there is potentially condensation in two different sides of the system. The wet side where the heat is dissipated and also when the cooler water is circulated through the occupied space there may be condensation on the other side of that surface as the warmer humid air gets cooled. As has been pointed out that moisture is what really must be contamination controlled as in any air conditioner.
Maybe it could be made into a quiet enough and small enough and service free enough system for a residence. It would of course have to be able to be decommissioned for winter. The amount of refrigeration BTU has to be weighed against the energy cost of continuous water pumping and running fans. On a small scale it might not pay much dividend for what is involved.
Industry would prefer to just dump their waste heat into a river but I think they do the cooling tower thing because they are forced to. Any I have been around are noisy.
A well designed cooling tower dosn't need a fan, just a spray of water. Used to drive by a monster of one at the Trojan power plant. Cool hourglass shape and usually a large colum of steam escaping the top.
Would the good design of such a thing not depend on the relative temperatures of the working mediums whether or not the thermosiphon effect can be powerful enough to accomplish the heat transfer desired with an economically feasible amount of structure? Some things, like the fact that the less intense the temperature differential the greater the area necessary to accomplish a given heat transfer; same thing for velocity. Trade offs can be made here to some extent but none of the effects can be forgiven. Some things dont scale down well either as ratios of area and volume dont stay the same.
Perhaps the calculations could be done using the figures of energy available from the evaporative cooling effect and the available air temperature differentials to arrive at some areas, volumes, velocities, etc. The figures of the heat gain of the building should be fairly easy to arrive at also.
http://www.thefarm.org/charities/i4at/lib2/aircool.htm
http://www.wbdg.org/resources/naturalventilation.php
Been considering designing one for our passive solar house.
Bob B
rm /
good info guys... keep it coming!
Yep, all excellent points Frank. Definitely some calculations involved to determine feasibility and design parameters.
I am fortunate to live where very little air conditioning is necessary, but I have traveled and worked in locations where life is really miserable with the heat so I can sympathize with the desire for air conditioning and the thought of finding it virtually for free is enticing. Certainly there are moves you can make to your advantage if you are designing from a blank sheet. Reading the links on some of the passive cooling schemes shown makes me think from the cost that it was done by the very wealthy and many of them are for quite exclusive climate conditions.
If you would be controlled at all by building code, insurance, mortgage etc., unconventional designs are expensive to actually put into being. Some of the ideas shown like running water in earth tubes openly connected with living spaces is only a step above open street sewers as a potential health hazard. That there are suggestions about sources for demineralized water to continuously bathe the evaporative cooling devices is a bit telling. Are these schemes that work only where total costs are of no consideration? I am skeptical that some of these are bragging about their countries venerable technology. I think Wiki mentions something about being unsubstantiated. A bit like the saying that the good old days are remembered most fondly by those with questionable memorys.
Anyways I would be very interested in seeing designs that really will function and give good bang for the buck in the face of todays conditions.
Definitely pros and cons associated with this. I think this has good merit if you live in a climate that is hot and dry, both day and night. If you live in a climate that is humid or is only hot during the day (i.e., gets cool at night), a better alternative might be a well insulated house with either active or passive whole house ventilation.
At my future location in southern OR, it can often be 100+ deg F during mid-day during the summer, but the temp will always drop to 50 deg F at night. So I am thinking whole house ventilation chimney (with roof egress zone shared with the masonry heater chimney) likely wins out. A well designed passive solar house tends to stay pretty cool anyhow because of all the thermal mass in the house, because it is super insulated, and because little sunlight/heat enters thru the windows during the summer months.
I have never been a big fan of earth tubes for some of the reasons mentioned. Plus, with my luck, one of my wife's cats would crawl in and get stuck. Then my life as I know it would be over :'(
Bob B.
Bob:
i have kind of come to the same conclusions, in east central kansas, it gets hot as hell in the summer months
not unusual to go well over 100 degree's for weeks on end, however it generally cools to the mid 60's at night.
the problem is the humidity is also higher at night, so this is my thinking
insulate the living crap out of the house, (existing structure), there are already no windows on the west side, which is a plus
but also need to make sure the other windows are efficient units, then
i will probably have someone come in and take out the concrete floor in the lower level (which is now a garage) insulate
and pour a replacement slab with pex so that it can become a large thermal mass, (hot and cold depending on season)
and i am also thinking of large centrally located stone fireplace with additional thermal mass and pex running through it as well.
then in the summer months close up the house during the day, to limit heat gain, and at night use the cooling tower
to remove the heat from the thermal mass of the floor and fireplace mass,
even though the humidity is higher at night and that will limit the wet bulb depression sustantially, i think it is possible
to cool the thermal mass down to perhaps 5 degree's under the outdoor ambient dry bulb temperature, or about 60degrees F
so by morning the slab and fireplace mass should be cooled to somewhere close to 60degree F, or at least 65 degreeF
which if the house is closed up tight and the heat gain is limited, i believe i can maintain the inside temps to something
under 80 degree's by late afternoon, at which time if it is necessary i can engage the forced air system to moderate the temps
for any shortfall in the more or less passive system.
so in the end i should be able to cut the A/C run time by at least 50% if not closer to 75% or more on some days.
on cooler drier nights it is possible to get temps below 60 degree's off the cooling tower.
then there is also the possibility to use a water to freon condenser that uses the now existing cooling tower so that
the forced air A/C system would run with less power or more efficiently.
i am thinking why not? the place is relatively small, the climate has a broad temp swing from day to night, and i have a real interest
in design and build of such systems anyway.
besides i have an aversion to hot summer heat!
bob g
Bob G.,
Sounds like a great plan to me. Just getting mass IN the house and being WELL insulated does a tremendous amount of good in stabilizing the inside temp and minimizing heating/cooling requirements. Might want to install a couple ceiling fans too.
Speaking of hydronic heating/cooling, I just learned that Amazon is finally shipping me the latest revision of Sigenthaler's "Modern Hydronic Heating". I have been patiently waiting for it to be released for over 6 months now.
Taco has some nice, free hydronic design software too:
http://www.taco-hvac.com/en/products/Design%20Tools/products.html?current_category=27
Bob B.
One simple cooling tower I've used was just a shower pan that was surrounded with 6' walls with 2" redwood slats tilted to drain into the pan. A sprinkler head centered at the top introduced the warm water. It worked very well.
But to do what you want Bob, you might want to take a look into some hot water solar panels. They can be used for heat during the winter and cooling during the summer by radiating the heat out into the sky at night. If you run the numbers you might be pretty surprised. I've heard of systems freezing at 44f. Our home has pex tube in the basement and main floor slabs and I've thought of cooling with the hydronic loop, BUT have decided not to try it due concerns about condensation. In an appt I lived in in D.C. there was a coil, probably from a freezer case going across one side of the living room above the sliding glass door. Cold water was circulated through this coil and water dripped into a "gutter" that surrounded the bottom and front of the coil. The same coil received hot water in winter. It worked very well.
In the design of our home we included a lot of interior concrete floors as thermal mass. The most we've seen for day time temps here is 113f, the house got up to about 75. It is also difficult to over heat the house with the wood stove and temps only drop about 3f with over night temps in the low 30's.
Sailawayrb, I like that idea of the ventilation chimney sharing the space of the masonry heater stack; Gosh, I am visualizing a spiral staircase around it! I like passive but it is not because I am a stranger to mechanical complexity; I made my living for the most part as a steamfitter, but I am well aware of the warts that show up with age on a system. I dont like being a slave to maintenance after the creative glow has faded. The slab heat hydronic is ultra nice heat, though I have reservations about it for cooling the living space directly but if not it is still a plus as you could use its cool liquid to enhance refrigerant air conditioning. Whatever a person could do to make as much of the system as possible work for both winter and summer would be a plus. The wet tower idea I would need some more convincing on!
An older gentleman who is dead now built a lot of active solar and heat storage ideas into his home 40 years ago when that technology was still quite new. His system was pretty complicated and personalized and only one of his techie friends could look after it when he was away. When it came time to sell they could not get a decent offer on it. Since it was on 11 acreas it eventually sold but for half the price a conventional system house would have fetched. The new owner demolished it as he only bought the lot. Fortunately it was after the old fellow died.
Quote from: Tom on February 08, 2011, 03:31:38 PM
<SNIP> take a look into some hot water solar panels. They can be used for heat during the winter and cooling during the summer by radiating the heat out into the sky at night. If you run the numbers you might be pretty surprised. <SNIP>
Tom are these evacuated tube units? I like the double duty winter/summer idea.
Great perspective as always Crofter. As much as we love our creative, innovative systems, they are not always well received by others and they can adversely affect future value and sale. I also like to avoid unnecessary complexity/technology whenever possible too. Complexity/technology should always have to earn it's place into a design.
Tom, while I also share you concern with hydronic cooling causing condensation, I am completely ignorant of this subject and will need to study up on it before I could provide anything worthwhile. I am hoping to use stamped/dyed concrete for the slab surface inside house (or perhaps natural rock looking tile). I am also thinking of modifying the house design so the main interior wall between bedroom and great room is a real brick wall. I put some preliminary house design renderings on Marcus's project thread:
http://www.microcogen.info/index.php?topic=1412.15
Besides adding contrast and looking nicer than all sheetrock, this brick wall will provide even more thermal mass. Given that the ceiling height is 10 feet, I will likely need to have another footing just to handle the load from this wall. Will likely need to consider seismic as well. Any thoughts would be most appreciated...as I am not currently a master brick layer either...but I will be...
Bob B.
I was talking flat plate collectors, seems that they radiate as well as adsorb heat.
We have a acid dyed light weight concrete slab on the main floor of our house. My concern is that the subfloor would rot if moisture condensed on a cool slab. As long as you're above the dew point you're ok, but that will change over the course of the night.
I think condensation could be a concern for mold on anything like bedclothes or curtains that touch the floor as well as slippery if the humidity reaches the dew point. Also I see possible stratification of a cold layer at the floor that is not easy to stir up. Ok if it is sweaty feet and not sweat on your brow that troubles you. easier to cool you if the cold air enters high and sweeps down and across.
Just wondering what depth drilled wells come in at and cost per ft in Bobs locale. Would not even have to be potable or have a high flow rate if it were used as a very long underground heat sink and heat source.
Tom, thanks on verifying plate collectors. Solar hot water may be next summer project. DHW presently by wood heat and that sure is worthwhile. Dont want to burn wood though in the summer. Trying to see what I can reduce useage to with some solar electric in the future. Dang we sure get used to using a whack of elctricity; at least a lot when you consider the cost of replacing it by solar.
RB, on the brick work; do it yourself if you need some creative outlet and dont have other things you would be better paid doing, Lol! I have laid 5 or 6 hundred blocks and built a chimney and a brick half wall behind the cookstove. I find it disgustingly slow compared to what we see for results from a real mason; probable less than 20%. With the construction industry what it is you could probably get one at the Salvation Army soup kitchen and you just mix the mud for him and look at the prints!
I recall reading somewhere on one persons house that they had radiant heat for the floor slab and then for cooling they had installed some kind of flat absorbtion plate chillers up near the ceilings with fancy controls to monitor humidty in the house so condensation would be eliminated. With a well insulated tight house there is also the need for air exchange to keep indoor polutants down. I think this house was located near Pueblo Co so there was not much outdoor humidity to begin with.
Quote from: Crofter on February 08, 2011, 07:12:59 PM
RB, on the brick work; do it yourself if you need some creative outlet and dont have other things you would be better paid doing, Lol! I have laid 5 or 6 hundred blocks and built a chimney and a brick half wall behind the cookstove. I find it disgustingly slow compared to what we see for results from a real mason; probable less than 20%. With the construction industry what it is you could probably get one at the Salvation Army soup kitchen and you just mix the mud for him and look at the prints!
Yeah, I have always been happiest doing things myself and the results have always better than the best professional would ever achieve. Slow going is OK as it is more the journey than the destination for me, and the satisfaction of doing something right yourself lasts forever. Of course, what else would you expect to hear from an engineer, glass blower, and sailor... :)
Bob B.
Quote from: Mack_59 on February 08, 2011, 07:27:17 PM
I recall reading somewhere on one persons house that they had radiant heat for the floor slab and then for cooling they had installed some kind of flat absorbtion plate chillers up near the ceilings with fancy controls to monitor humidty in the house so condensation would be eliminated. With a well insulated tight house there is also the need for air exchange to keep indoor polutants down. I think this house was located near Pueblo Co so there was not much outdoor humidity to begin with.
Welcome Mack!
Yes, I see that Taco sells chillers for their hydronic systems. The controls appear fairly complicated. Yes, I will certainly need a Heat Recovery Ventilator (HRV) to meet code and successfully accomplish the mission.
I can confirm there isn't much humidity in Pueblo Co... I worked at a steel mill (CF&I) in Pueblo one summer during my college days. I remember flat, dry, and windy...but nevertheless a very nice place relative to my NJ reference point at the time. :)
Bob B.
as luck would have it, the little house i bought not only is connected to city water and sewer, but also has
a good well in the main floor garage and another out on the side lot, the one out in the side lot was used to
water the former owners massive garden, the one inside i have no idea what the story is on it other than the old
dude likely wanted a water source just in case the world came to an end?
i don't plan on cooling the slab below the dew point, that will be a trial and error thing to learn how to avoid that happening, and
as far as air exchange, i plan on having most of that done either very early in the morning or in the late afternoon or evening with
the temp balance is met (inside vs outside temps at or near parity)
i am going to try to avoid air exchange during the hottest part of the day, perhaps the air quality will suffer a bit for a few hours
but heck i am old and ain't gonna live forever anyway.
:)
gotta get a bite to eat, later i want to relate a couple of other interesting evap systems i came across that i found very interesting.
more to come...
bob g