let the insanity begin

[gpajon]

I wish that were true. I would be a happy camper I have pumped water from 120' down and it is only 74 degrees. At the 6' depth I have my geothermal I think it is about 77 if my gauges are right.

Matt,
77' should be pretty accurate. I got 80' at 7 feet and I was measuring the water seeping in from the water table not the ground itself. I have scrapped the Geothermal project till something new comes to mind.
Matt how have you been dealing with the cold these last couple of weeks?

 

[gpajon]

Here is a diagram of my original loop.

http://community.webshots.com/photo/97250273/161727017PYITjV

 

[Treeman]

I use a heater like Ricks. 200,000 btu monster, it can hold what ever temp I want but is a little uneven like Ricks too.

That is the same loop that I used but with different piping parameters. There has to be a better way to do it down here.

 

[rick rottet]

WHOA. What a blessing to have all of these folks participating. So many of whom I have read their inputs in other threads and really respected and admired. Rick wipes tear from eye .

cseeton (and everyone else)- My thinking on the salt was to use road salt (cheap if you can get it). I was thinking that as the salt absorbed moisture, it would just dissolve away. There would be a big pile of it from which I would replace the dissolved portions on an as needed basis. This salt would sit outside in front of the shutters in some sort of container which would allow air to pass through. The drier air would then pass through the DIY evap pads to increase the cooling capacity of the pads. Any way to figure out how much this would help? Is there a way to figure how much the DIY evap pads would help in and of themselves? One concern I do have with this hypothetical plan is the small amount of water that would be in the wallpaper trough. Seems like it would heat up fairly quickly and lower the efficiency and try to run dry quickly. Of course, now that I need to run an RO before the DI, the waste water from the RO could be piped to the trough to replenish it and cool it.

Some of you referred to a spray. Are you talking about spraying a mist inside the greenhouse? or spraying the evap pads?

Just to clarify, the geothermal loops are thermostatically controlled, right?

But, wouldn't you and your family like an above-ground "heated" swimming pool this summer - the bigger the better? Toss a heat exchanger on the filtration system and a variable speed pump to circulate through tubing installed in the tanks then use the night sky and night evaporation to cool it down at night. You would have a giant heat resiovor to dump heat into all day long and it would be just the right temp when you get home from work...

This sounds very interesting. Would this all be plumbed above ground as well?

Speaking of work, I'd better go get ready. Don't mean to neglect so many of those who are contributing, as usual, I'm crunched for time. I'll be back this afternoon, you guys go ahead and keep brainstorming.

 

[cseeton]

Yes, everything would be above ground since you will only need to supplement direct evaporative cooling of the tanks in the hot months.

This is only a vision, but I think it has a very high likely hood of being a cheaper alternative to ground sourcing in the Illinois climate (unless you live on a shallow aquafier).

Ground sourcing most likely has a much lower lifetime cost - if you implement a heat pump. However, with the furnace, evaporative cooling and a little relief on the hot days you will be able to maintain pretty good temperature control without the added technology.

 

[boxer85]

I wish that were true. I would be a happy camper I have pumped water from 120' down and it is only 74 degrees. At the 6' depth I have my geothermal I think it is about 77 if my gauges are right.

ok, several people commented on this, and let me clarify my statement

I said GROUND temperature, not water temperature. water moves quite alot, even underground. it can come from underground springs, or can be from surface runoff, or can be underground rivers.

on that note, I did a bit of searching and found over this

"From Montana's -70 degree temperature, to the highest temperature ever recorded in the U.S. - 134 degrees in Death Valley, California, in 1913 - many parts of the country experience seasonal temperature extremes. A few feet below the earth's surface, however, the ground remains at a relatively constant temperature. Although the temperatures vary according to latitude, at six feet underground, temperatures range from 45 degrees to 75 degrees Fahrenheit. "

over at the Califronia Energy Commissions website
http://www.consumerenergycenter.org/homeandwork/homes/inside/heatandcool/heatpumps.html


now, i couldnt find anything on the ground temperature of illinois, however, i recall learning at some point in my past that it was 55 degrees....

 

[Treeman]

But you said anywhere in the non frozen world! 45-75 degrees is different than 55.

All in good fun, I was just bustin your chops. :fun5:

 

[rick rottet]

weeeeeeeeeeeeeeee

ok, one by one

cseeton- can you explain a little more how removing water from the air with a desiccant heats the air? How much less does warmer air decrease the evap cooling potential of that air?

It seems like there are two parts to the evap cooling thoughts. One is cooling the air coming into the greenhouse to lower the ambient temp inside the structure, thereby controlling the tank water temps. The second is evap cooling of the tanks themselves.

I would agree that the swimming pool might hold some great potential. If the pool water never gets above 80 and holds three times the total volume of the tanks in the greenhouse, it seems like I would at least be able to have the tank temps equal out. i.e. The tank temps could be brought down to 80 just because of the sheer volume of water in the swimming pool. I don't have the knowledge/ numbers/ formulas to work all of this out, but someone surely does.

By spray, do you mean a fine mist directed at the pads as opposed to constant pouring/ trickling of water over the pads?

My main concern, and from what it sounds like, everyone else's concern who is trying to figure ways to combat hot summer temps, is being prepared for the worst case scenario. The worst case may not happen or happen only once in ten years, but if it kills off a greenhouse full of corals, then the initial expense of being prepared may well have been worth it. Around here, that might be 110 with 95% humidity. Are there equations/ formulas to figure out how much temp drop you can get with different methods. Like starting with fans. I know, just from experience, that my big exhaust fan will easily drop the temp in the greenhouse by ten degrees in a matter of minutes. Some have already said there are numbers available to figure the footage needed in an underground loop, are there similar numbers available to figure how many degrees a fan will lower the temp? Evap pads? Evap pads with desiccants? etc... I think we all also want to have the cheapest solution that will effectively do the job. With so many inputs, I was figuring if we all start with a set of standards (given temp and humidity) and work from the cheap and simple solutions to the more complicated and costly, it would benefit the most amount of people.

H2OENG- this is a killer thread, but due to all of the inputs from other people, I'm just showing off pictures and learning tons.
Geothermal is not out of the question, I just want to know that a cheaper, easier solution wouldn't be adequate. In my own thoughts, I was convinced that fans and pads (and maybe the addition of the salt) would do it for me. There have been quite a few people questioning the adequacy of the cooling plan so I want to try to get some concrete numbers flowing and figure it out. I don't have allot of experience with these systems, so I can't just "look at it" and tell if it will be enough. The solar panel idea sounds like it might be easier to employ and cheaper as well. Then, do we just count on the tank's water not heating up quickly during the day? Won't the solar system heat up during the day, then when it turns on at night, create a sudden in flux of warmer water until the circulation pushes it through the system? I don't know how much difference that would make compared to the overall system volume, just a thought on my part. Would the water from the solar system then be piped through a heat exchanger like a geothermal would be?

matt- If need be, those are good ideas.

boxer85- Also good ideas, I just want to exhaust cheaper, easier methods first.

seldon- That may be true, I wouldn't know for sure. The system, I think, would still be much the same and require much the same equipment to operate and the same amount of work to set up.

Treeman- thanks for jumping in and thanks for the water testing links. Have you also seen the misting systems that set up outside the GH and mist the plastic? Combined with a shade cloth, they are supposed to be fairly effective at cooling the plastic by evaporating water from the shade cloth. Atlas sent me an experimental summary written by D.H Willits and M.M. Peet at the U of California. The original write up was in the April 1994 and December 1994 issues of The North California Commercial Flower Growers Bulletin. It supposedly made the evap cooling pads run 40% less of the time because of the cooler temps.

gpajohn-I have seen your inputs on other threads and appreciate your input here. I wish you the best in your endeavors and thanks for the links too. Maybe some of these alternatives will help get your creative juices flowing again!

Again, thanks to everybody for their input(s). I hope you keep them coming. RC is one great resource for all of us to share and benefit from.

 

[H20ENG]

Rick,
You asked if the trough water would heat up and dry out..
Actually it will cool down. This is the basis of cooling tower operation. The water gives up its heat to the air as it evaporates. On a cooling tower, the water passes over the media, and some water evaporates. This cools the water, but also increases TDS (only the water evaporates, not the dissolved stuff in it). So you will need to add a float valve to the trough for water makeup to replace whats evaporated. You will also need to put in a blowdown valve to get rid of the super high TDS water before it crusts up your media, pump and plumbing. (Keep it below 1500 TDS)
The geothermal does work, and will work much better than evap cooling IF the outside temp and humidity get too high.
The critical # is the WETBULB TEMPERATURE of the outside air. This is the temp that if the tower is doing all it can, you can get the water close to. On a 110 deg day with 95%, you are only going to cool to about 100 - 105deg.
But on a 110 deg day with 30%rh, it will cool to about 82deg. If your climate is high humidity, evap cooling is not as helpful.

With the night sky radiation that I've seen (read about), the water is stored in a big underground tank for constant cooling during the day, and the "radiators" drained during the day. But there we have a big tank again....

I thought about putting misters on the plastic. It would help a bit, but you would get encrusted solids and or algae buildup on your plastic. You would have to acid wash the plastic periodically.
In a pinch, though, I would definitely break out a sprinkler!!

Treeman,
With a compressor in the loop ( this setup is commonly called a ground source heat pump), the high side temps are much higher, and the low side much lower, since it is a refrigerant based system. The compressor takes the high side to about 200deg. This will be given up to the ground loop. Then the evaporator will cool the tank side loop to maybe 50-60 deg, which will absorb heat from the tank system. The heat moves from the tanks to water, via a water to water exchanger. Then on to a water to refrigerant exchanger (evaporator). The compressor moves the heat to the high side refrigerant to water exchanger (condenser), and the water then transfers the heat to the ground. It sounds like a lot, but refrigerant is pretty efficient at moving heat (which is why its used as refrigerant)

 

[H20ENG]

Rick,
Find a psychrometric chart to look up your temp / rh #s to see what kind of temps you will end up with with evap cooling.
I dont know the #s as far as sizing the media or fan cfm. You could look up a tower supplier and copy #s for them.

 

[tschopp]

tschopp- how does your formula equate to heat gain? Do you have a conversion formula/ factor?

That is the maximum heat that could be input by solar. Not all of it will make it into the greenhouse, some will reflect off the water surface and some will reflect off the bottom of the tank. I don't know what the exact number will be, but for an unshaded tank in the summer I would think the value that goes into heat will be in the 50% - 100% range. So if your 400gal tub has an area of 3 m^2 you are looking at 1500W - 3000W of heat input. I would guess it will be closer to 1500W. But this the peak solar. If we assume a clear day that last 14hr the total heat input will be 1500W * 0.63 (normalized intergral of sin function) * 14 hr = 47.6 MJ energy.

The latent heat of vaporization for water is 2.26MJ / kg (this is the heat that is removed when the water evaporates)

So you would need to evap 21 liters or 5 1/2 gal per day to remove the heat for this tub.

If you use some shade cloth the evap requirments will be lower. But just remember this is only the solar part of the heat input. If the air is 95 and the tank is 80 you will get quite a bit of heat from the air.

When I heard you wanted to do evap cooling I thought you were going to do it in a way that promoted the evap of water out of your tanks. Including possibly a cooling tower that took tank water and activly blew air by to promote evap ( you can only get so much evap off the surface of the tank no mater how much air you blow past).

It sounds like you are planning on cooling the air as it comes into the greenhouse. This will lower the air temp a little, but it will also reduce the evap rate out of your tanks because the air in the greenhouse will be more humid. I don't see much net improvment in cooling with that situation.

The pool idea sounds good. It would be a great thermal resovoir and as long as it stayed below your target temperature I think you would be in good shape. Definatly easier to get good control over temp than with evap cooling. Just remember when you need the most cooling you have the least evap ability. When the temp is in the 90's with dew points in the upper 70's you are screwed on evap cooling. In the worst part of summer my evap system can't handle the cooling and the house AC has to take over for a couple of weeks.

Steve

 

[tschopp]

At work we run a weather tower in Newport IN. It is just across the state line on US 36. So the weather is amost identical to me in tuscola and should also be pretty close to your weather. I could get you a couple of years of data if you would like. It has useful stuff like temp, RH, solar radiation etc.

It could be used to figure out useful stuff like what is the average wet bulb temp in a typical summer. Or just how dark and gloomy does it really get in winter.:lol:

 

[matt the fiddler]

could you price some of those BIG BIG BIG vats/ Reservoirs at a farm store, and maybe bury a few of them right outside your green house for the water volume? if they are exposed to sun or air, they will loose a lot of their efficency... but i have seen several that would be big enough for your operation.. heck my uncle has one buried up at his cabin in colorado..

or even better. dig the hole along the side of the wearhouse 10' deep [a cube would minimize covering costs], put the liners in that they use in ponds, and find some way to cover it with a white tarp..

too bad you don't have a natural pond nearby that you could cover, clean the gunk out and use

 

[scubadude]

When I heard you wanted to do evap cooling I thought you were going to do it in a way that promoted the evap of water out of your tanks. Including possibly a cooling tower that took tank water and activly blew air by to promote evap ( you can only get so much evap off the surface of the tank no mater how much air you blow past).

It sounds like you are planning on cooling the air as it comes into the greenhouse. This will lower the air temp a little, but it will also reduce the evap rate out of your tanks because the air in the greenhouse will be more humid. I don't see much net improvment in cooling with that situation.

Steve

Some good stuff there Steve

And I agree with you on the evaporative cooling.....Evap cooling by evaporating your tank water is also much better for larger volumes where you have to keep your CA demands high. Like SPS or Clams. Even with softies I had a tough time keeping my CA and Alk demands w/ just 2 part cuz they are such big systems....However if you use Evaporative cooling and your topoff water is all limewater, which you can get hydrated lime in bulk for fairly cheap then the more you evaporate your tank water the more lime you can put into your tank....its a trade off that you have to consider Rick (you will use more Water this way but I think it might be worth it)....temp and ca/alk levels Just wanted to throw that thought into your head.....Cuz I know your trying to think as much in advance as you can.

Keep this thread smokin guys I know we can figure out an effecient approach to the whole outlook.

 

[cseeton]

Let's try and sort things out a bit, hold on as I step up on my soapbox...

Let's start with a psychrometric chart: Psychrometric Chart

All desiccants (liquid and solid) heat the air as water is pulled out. The process is isenthalpic (constant enthalpy, nearly constant wet bulb). This causes the air to drop humidity ratio, but also increases the temperature of the airstream.

Road salt will work - to a point - the problem is that it is quite coarse, does not expose much surface area for moisture absorption, and it saturates quickly and on doing it liquefies and fuses the rest of the salt into a solid block (ever wonder why they put rice in the salt shakers down south - to absorb the moisture). Industrial desiccants are usually silica, alumina, or liquid salts like lithium chloride. Now the real problem is that since we are tied to the wet bulb line, if the outside has a wet bulb of 85F then that is the best we can cool the water to without refrigeration.

Water pads with water circulation. Here we cool the air by adding moisture to it we can cool the air in the greenhouse so can then cool the water, but additional water will not evaporate from the tanks. Let's call this indirect evaporative cooling, and we are still tied to the wet bulb in this process as well.

Direct evaporative cooling of the tanks themselves. If we blow air over the tank water evaporates and thus cools the tank. Very efficient and very simple. If add a pump and shoot water into the air and let in land in the tanks we can make it more effective, but still we are tied to the wet bulb.

Refrigeration systems - work extremely well and easy to implement. Unfortunately the drawback is the electrical cost, but even that is not all bad as it is a very good cycle and has extremely good controllability. If it is air based then it has a very low starting cost and you pay more for electricity, if it is tied to a ground loop then there is a high initial cost and lower electrical cost.

Groundloops are very good, but you pay for digging up your yard and lying pipe. But wait - there is a farm behind you could you get permission to use a trencher early in the spring to put it alot of tubing? Tell the farmer that you will gently heat the roots of his crop with a ground sourced heat pump... There might be merit here.

Treeman - with only 100 feet of tubing you have about as much cooling capacity as a large refrigerator. Why did you use copper? The limiting factor is not the tube material it is the ground itself.

For the pool, we would use the huge thermal mass of the water as well as a fountain or spray to really cool it down at night. Here we are again tied to a wet bulb temp, but it is a combination of the nighttime wet bulb and the daytime wet bulb. We can't use the nighttime wet bulb for the tanks because there would be a risk of cooling the tanks too much. Additionally, makeup water would be cold from the city. Call this option a peak time heat sink, because you do not need to run if full time, but rather only on those days when direct evaporation from the tanks don't quite give enough cooling.

I don't know if this helps or not, but we should have fun with it!

Chris

 

[gpajon]

Treeman - with only 100 feet of tubing you have about as much cooling capacity as a large refrigerator. Why did you use copper? The limiting factor is not the tube material it is the ground itself.

I believe this question was directed towards me.
I used only 100ft of tubing for 2 reasons. First it is a small experimental system with only about 400 gallons total, second I figured at the time that because I was using metal and metal had better heat transfer properties and I was burrying it in the water table that I could get away with less. I used copper expecting to get better heat transfer than I would with PVC not knowing at the time that the ground temps would only get as low as 80 deg. When I burried it I didn't measure the ground temps as I should have. I attempted to burry another 100 ft at 7' this time, however when I measured the temps I was only getting 80 deg readings. Limited by the 80 deg ground temps I scrapped the project.

Treeman,
I bet you must be pretty frustrated with this issue. I am not growing anything commercially and I am frustrated myself. The thought of using a geo-heat pump is starting to catch my attention.

H20eng,
What do you think about adapting a 1hp chiller to work with a geo-loop?

 

[cseeton]

Oops, your right. Sorry.

Yeah, water tables can screw things up, espically in FL. You will need to tie it to a heat pump/chiller system and reject the heat at 80F. A 1hp chiller will need at least 200 ft of tubing - you might need 400 ft if the line spacing is tight or unless you have flow in your water table.

 

[gpajon]

I was thinking of having a couple of deep wells drilled and running vertical loops.

 

[hammerhead_77]

First off, I am in awe of what you have done.

I hesitate to say anything, given the number of highly educated opinions, but here comes the layman anyway.

Would it be possible to bury one to many larger tanks in the ground such that the capacity of buried tanks was equal to or greater than the volume of the propagation tanks. Those tanks will act as both a geothermal sink and a nice reserve of water volume. Think of it as a buried sump. Your pumps would pull from the buried tank, and the return from you filters would go back into the tank. Depending on the temperature, increase or reduce the amount of water that you are pulling from the buried tanks.

I used a "ghetto" version of this last summer (on a very small system) and I think that O2MANYFISH here on RC uses a similar system.

It was lower cost for me than going with the chiller.

Great work, please keep the updates rolling in!

 

[LegoZ81]

Rick, what about this have a PVC heat exchanger in each tank, have these run to an insulated vat buried outside (it does not HAVE to be buried but it will look better), have a second PVC heat exchanger and a pump in the vat. (closed loop)
Fill this loop with RO/DI water.
Fill the vat with a low tox antifreeze (also help prevent corrosion due to electrolysis)/water mix circulate this with a good pump.
Depending on peak BTU exchange that you will nee (I think you con convert Joules to BTU) choose a window AC unit.
Gut the unit (I'll help if you want) and immerse the Evaporator (the cold side is the evap right) in the vat. build a small "pump" house style building to protect the compressor/and house the Condenser. you should be able to then hold water temp in the tub ~ 45F w/o too many problems unless heat output is extreme. You would only turn this on in very high heat situations and should easily keep heat level of the tanks under control (depending on heat exchanger design in the tanks.)
Window AC units can be snagged up at ~ 105 dollars for high efficiency models at wal-mart if you watch prices.
If you do a common sump you'd lower your over cost of tubing by placing the heat exchanger there.