geothermal chiller
- Thread starter Frankie1
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I think an easy method to determine the correct flow would be to pick a time, probably night time with out lights, when you should have stable tempature readings. Using a ball valve, set the flow to a low gph, then take a tempature reading from the return of the geothermal line.
Then increase in small amounts of flow and give it time to settle the temp out and retake the tempature. Kept doing this until you get a raise in tempature and when you get this raise ,just adjust back a little and you should have the best setting for your geo thermal system.
Then increase in small amounts of flow and give it time to settle the temp out and retake the tempature. Kept doing this until you get a raise in tempature and when you get this raise ,just adjust back a little and you should have the best setting for your geo thermal system.
looser
New member
Hear are my thoughts (such as they are) on the benefits/drawbacks of fast vs. slow flow rate.
In a closed loop system it makes sense to me that the flow rate be high. All of the surface area of the coil would have a greater temperature difference, thus faster cooling. (if you where to put water in liquid nitrogen it would freeze a heck of a lot faster than putting in a freezer). Because its closed loop the pump would use very little electricity to circulate the water, and you would have no waste water.
However in an open loop system, where water conservation and minimizing pump run time, are important I think a slow flow rate makes sense. The cooling wouldn't happen as quickly because as the temp of the cooling water goes up it would have less cooling power. But you would get maximum utilization of the water, and minimize pump run time. So a larger coil would probably be required to get the same rate of cooling as you would get with a higher flow rate.
Then again....I might be completely wrong.
Cuby 2K - The inlet and outlet are 1" and the plate material is .0197 inch thick. I really don't understand how the thing would work. Maybe the plates are like fins on a car radiator? The surface area is 1.36 FT2 (whatever that is) I would post the PDF file but don't know how. I guess I don't know much.
Bill - Thank you for chiming in. Hearing from someone that is actually doing what I want to do (on a MUCH bigger system no less) is very refreshing and encouraging. Please tell us more! How often does your 500 gallon tank fill? Do you ever have to dump the water or does your RO/DI keep up with it?
Alfinus - Thanks for the info on ss. I will look into that more.
In a closed loop system it makes sense to me that the flow rate be high. All of the surface area of the coil would have a greater temperature difference, thus faster cooling. (if you where to put water in liquid nitrogen it would freeze a heck of a lot faster than putting in a freezer). Because its closed loop the pump would use very little electricity to circulate the water, and you would have no waste water.
However in an open loop system, where water conservation and minimizing pump run time, are important I think a slow flow rate makes sense. The cooling wouldn't happen as quickly because as the temp of the cooling water goes up it would have less cooling power. But you would get maximum utilization of the water, and minimize pump run time. So a larger coil would probably be required to get the same rate of cooling as you would get with a higher flow rate.
Then again....I might be completely wrong.
Cuby 2K - The inlet and outlet are 1" and the plate material is .0197 inch thick. I really don't understand how the thing would work. Maybe the plates are like fins on a car radiator? The surface area is 1.36 FT2 (whatever that is) I would post the PDF file but don't know how. I guess I don't know much.
Bill - Thank you for chiming in. Hearing from someone that is actually doing what I want to do (on a MUCH bigger system no less) is very refreshing and encouraging. Please tell us more! How often does your 500 gallon tank fill? Do you ever have to dump the water or does your RO/DI keep up with it?
Alfinus - Thanks for the info on ss. I will look into that more.
douggiestyle
New member
all of the ss products that may leach into the water are in reef additives.
Bill Wann
In Memoriam
It keeps up with the flow pretty well , I have a 4000 gallon a day ro system and I use it to wash my cars . So sometimes I dont have enough water in the tank and have to add some . In the past I have used a 100 foot coil of 1/4 poly tube connected to the house water as a heat exchanger and it works great , I have on on my friens system thats 600 gallons , his tube is 300 feet lon thou and sits in his sump .
douggiestyle
New member
no offense any one but as far as slow for better heat transfer. YOUR WRONG. wrong wrong wrong. and there is no argument. because anything other than faster for better heat tranfer would be wrong.
ok.
now here is an example when slower may mean better.
you have a liquid that must be at a certain temp and it is running through a linear sytem and the chiller was not adjustable. one temp going in and final temp coming out. you would need to slow the flow if it was coming out at too high of a temp. of course this would reduce production.
ok.
now here is an example when slower may mean better.
you have a liquid that must be at a certain temp and it is running through a linear sytem and the chiller was not adjustable. one temp going in and final temp coming out. you would need to slow the flow if it was coming out at too high of a temp. of course this would reduce production.
ChemE
New member
douggiestyle is correct. If there is one thing that chemical engineers learn how to do it is design and size heat exchangers. One point that is hammered is to size tubes and flow rates such that the flow is turbulent. Turbulent flow produces a very thin laminar sublayer which is a poor conductor of heat. Laminar flow results in a thick laminar sublayer which further restricts the RATE at which a tube can pass heat. This is what produces efficient heat exchange.
A very slow flow rate will eventually reject the same amount of heat, but the tubing required to do it becomes ridiculous.
A very slow flow rate will eventually reject the same amount of heat, but the tubing required to do it becomes ridiculous.
As a comparison:
I'm using a MAG 3 (350gph) on a solar heating system for my pool
Each panel is 2' x 20' - I had one set - 2 panels connected last year. They advertise 80k btu from each set of panels & 10 degree temp increase
I leave it on a timer & it kicks on at the hottest part of the day
I have a 16'x32' inground pool & it stays well between 82-84 all summer. I have a cooling effect of a stream about 25' from the pool - keeps the ground cooler
I have 3 more sets of panels to connect this year
I'm hoping to hit 90
When the pump 1st starts up on a hot day, you can't put your hand under the output. I did a test shortly after it was running a while & the water coming out was about 88, water going in was 78/80 as I remember
A bit different - absorbing heat from the sun
When they put my 24'x36' garage/addition foundation in I'm planning on running a couple ground loops
Hopefully by then the water table will have dropped in MA
The stream is usually only 2-3" deep
I'm using a MAG 3 (350gph) on a solar heating system for my pool
Each panel is 2' x 20' - I had one set - 2 panels connected last year. They advertise 80k btu from each set of panels & 10 degree temp increase
I leave it on a timer & it kicks on at the hottest part of the day
I have a 16'x32' inground pool & it stays well between 82-84 all summer. I have a cooling effect of a stream about 25' from the pool - keeps the ground cooler
I have 3 more sets of panels to connect this year
I'm hoping to hit 90
When the pump 1st starts up on a hot day, you can't put your hand under the output. I did a test shortly after it was running a while & the water coming out was about 88, water going in was 78/80 as I remember
A bit different - absorbing heat from the sun
When they put my 24'x36' garage/addition foundation in I'm planning on running a couple ground loops
Hopefully by then the water table will have dropped in MA
The stream is usually only 2-3" deep
looser
New member
Your kidding me right? 4000 gallons a day
How many cars do you have? Let me guess, your the CEO of GM. Never mind I don't want to stray off topic.
I thought of using the 1/4" plastic tubing but I've read (maybe even earlier in this thread) that is something like 200 times less efficiant at transfering heat than titanium. (althoug if my $1000+ quote is any indication its also probably 200 times cheaper as well)
looser
New member
I believe you....... but doesn't there need to be some balance?
Lets say you have 100 gallons of cold water to work with, and you have one coil, and two pumps.
The first pump has extreamly high output. It will push the entire 100 gallons through the coil in 15 seconds. You would get almost no cooling effect from the cold water right?
The second pump takes 15 hours to pump the same water through the same coil. The cooling effect would be much greater.
I don't get it?
Maybe what your reffering to is in optimum condtions you would have two coils, each designed to maxmize the heat tranfer at a given flow rate and the coil designed for high flow rate would be more effeciant than the coil desinged for a low flow rate?
So in that case the 100 gallons in 15 seconds would be pumped through a 1000 tiny tubes each with lots of space between them and plenty of hot water flow around them. In which case you would gets lots of heat tranfer in a very short time. In fact more heat tranfer than you would get pumping the same water through the same coil over a longer period of time.
That makes sense. But If I'm understaning this, having a coil specificaly desinged for the hire flow rate is critical.
Am I even close?
Last edited:
looser
New member
<a href=showthread.php?s=&postid=7387955#post7387955 target=_blank>Originally posted</a> by Bill Wann
I dont like american cars , Italian and german , Its funny your name is the same that I have on my liscens plate .
We have really bad water here and its well water , so its liek rocks coming out of the tap , I use ro for everyting .
That is funny. Whats even funnier is that I have the same name painted on the side of my private jet..... unfortunatly I don't have a picture of it share with you.
. . . cool man.xrunner1234
New member
I think you're missing the point. If the goal is to get cold water.. say from a water fountain, yes to want low flow to cool the water.The inlet temp is warm and the outlet is cold. The exaust water is cold but at a very slow rate. Approach near zero flow and the drop just before exiting the pipe is the near the same temperature of the heat exchanger.
Since they're are near the same temperature the heat exchanger is removing almost no energy since the DeltaT of the exchanger approaches zero (basics of thermodynamics). Maximize flow and you get a larger Delta T across the heat exchanger to water boundary but the difference in temperature between inlet and exhaust is small but energy removal is greater.
This is analogous to a simple fan blowing in a light hood. Put a small fan with a low flow and you get a hot exhaust temperature. Increase fan speed and exhaust temperature goes down but. Does this mean that the low flow fan is cooling better since you feel hotter air?
looser
New member
I don't know the more I think about this flow rate thing the more I think that although in a perfectly designed system its probably true that higher flow rate is more efficient that a lower flow rate. But I'm talking a margin of error of +- 50%. How much efficiency can really be gained by increasing flow?
See that . . . . I was ready to give up.. and just go out an buy something and learn through trial and error. . . and you guys had to suck me back into this thinking thing. Damn you.
See that . . . . I was ready to give up.. and just go out an buy something and learn through trial and error. . . and you guys had to suck me back into this thinking thing. Damn you.
looser
New member
Do you ever get the feeling that someone is talking a different language even though it looks like a language your accustom to?
I'm just busting you dude. The same thing happens to me at work on conference calls with our IT department. Just don't start talking about protocol stacks please...
I don't know what a Delta T is, but I do think I understand your fan analogy. Of course the bigger fan would cool more, but you would also be pushing a whole lot more air, or in this case, water. Something that would be important to me in an open loop is to conserve water, so I'm still back to a lower flow rate. Even though it might be less efficient, I'm trading less water for lower efficiency. Right? Or maybe not. I don't know. I give up.....again.
looser
New member
Bill - Thanks for the Pics and the referance to the Polar Eyes. Heres the link
http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/9229/cid/2197
Better than the $1050 quote I got, but $700 or $800 still seems like a lot to me for a coil? I'm thinking I can just get some 3/8" titanium tubing, or high grade ss, and make my own for a lot less? I'll have to look into that some more.
douggiestyle
New member
havent had time to read all posts so if this was discussed excuse me.
we are not going to redesign nature so what it is, is what it is.
but that 100g situation if it was linear yes. slow it down IF you want a certain temp reached on the 100g. event still you would get better results by increasing the length of the tubing and increasing the flow accordinly. slowing the flow in this situation would only be a bandaid to controll the quality of your output.
but we want to control the temp in the tank. so your best bet would be to put that 100g on a recirc setup and pump the he2xl out of it.
the best way to understand this is wind chill effect. we all deal with this on a regular basis. do not confuse this with evaporative cooling. the stronger the wind blows the faster you freeze. i have mentioned this earlier in this thread. the wind blowing does not create a cooling effect (when you subtract evaporative cooling) because if it was hot out the stronger the wind blew the faster you would cook. ok that would be pretty hot but, you get the idea.
