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Author Topic: DIY water chiller - reading suggestions?  (Read 9938 times)

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #90 on: August 29, 2021, 04:16:42 AM »
I looked at some websites, but haven't been able to find a 1 ton R410a TXV.  They are all for larger units. 
If I move the unit, that would be the time...


32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #91 on: August 29, 2021, 01:51:18 PM »
Bruce,
I will make a couple of phone calls tomorrow and see
what I come up with.
I did talk with the local supply house when this project first
started. They build them in house. I remember my friend that works
there said he would have to order the body as they didn't have
one in stock.
I'll get back with you tomorrow afternoon.
I have a couple of other places I can call as well.

Gary

« Last Edit: August 29, 2021, 01:53:02 PM by 32 coupe »
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mobile_bob

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Re: DIY water chiller - reading suggestions?
« Reply #92 on: August 29, 2021, 03:09:48 PM »
i have a question for those that calculate this stuff

a hypothetical system, the names have been changed to protect the innocent :)

say a system moves the water at 2 gallons per minute and drops the water flowing through it by 6.5 degree's F

do we use the formula ...  500 x gallons/min x temperature change
if so then in this examples (500 x 2)x 6.5 = 6500 btu's?

if this is true

then would the same system running at 1.5 gallon per minute and a 10 degree change would work out to  (500x1.5) x 10= 7500 btu's?

is this basically how you determine an efficiency curve for the gallons per minute through the exchanger?

the reason i am asking, is i had planned on a similar system as Bruce but using the engine driven automotive compressor on the s195 trigenerator to cool a water loop in a set of cast iron radiators within a small superinsulated home.

this is the first time that i have seen an actual build in process, even if it uses some different parts.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

mobile_bob

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Re: DIY water chiller - reading suggestions?
« Reply #93 on: August 29, 2021, 03:15:37 PM »
would any of these be small enough?

https://www.rparts.com/index.php?cPath=84_13_24_68&osCsid=ba5nl9i8m4pavjk6p0k0f0nfr5

i haven't followed this company in years, but they used to make complete kits of parts to make small systems for the boating industry and were geared toward diy but made a change when the epa got more sticky

bob g
otherpower.com, microcogen.info, practicalmachinist.com
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32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #94 on: August 29, 2021, 03:23:36 PM »
Bruce,
I would try the evaporative cooling on the condenser coil. To test just drizzle water on the
coil. In the end you could use a solenoid that turned on water when the compressor runs.
I would try that first and check your pressures/temps. I bet it will drop considerably.

You may find with the condenser cooling and a small adjustment in charge (let out a small
amount) will result in better numbers.

Just a thought. Might save buying a txv.

Gary



Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

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32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #95 on: August 29, 2021, 03:30:37 PM »
Bob,
All those valves are for low temp gas and pressures. They may have 410 valves......I didn't look.

As for your question about calculations Russell will have to chime in on that. He knows those numbers
much better than I do.

Gary

Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #96 on: August 29, 2021, 03:59:24 PM »
Thanks, Gary.  I have found zero 1 ton, R410a  TXV's online so far.  I suppose that's because the 1 Ton mini-splits have electronically controlled expansion valves for their variable frequency inverter driven compressor.  Today, PWM control of a solenoid type valve is commonly used to create a linear valve control.  An EMI cannon in EMC parlance, something I'd rather avoid.

Bob, yes, you're right for the BTU hrs calculation.  BTU hrs= 8.34 lbs/gallon, X GPM flow rate X times 60 minutes per hour X degrees F water temperature change.  8.34 X 60 is the 500 you used, the proper multiplier.

Bronco's comment about my  former window AC unit's condenser performance gave me a thought this morning;  I'm at 5600 feet, and both the fan performance and lower air density effect on heat transfer will lower condenser performance.  For combustion it's about 23%,  for air flow and heat transfer, perhaps similar.  I'll do some research.

Things that might improve condenser performance (shading, evap cooling) could help greatly (as Gary suggests) because of this sub par condenser performance.  If designing from scratch, I'd put an upsized 1.5  ton  condenser coil and fan on a 1 ton compressor. 

My next step for a sunny hot day is to measure the effect on house slab and air temperature with 5 hours of run time to see if I can meet my goal of 4 degrees of heat extraction while still avoiding condensation on the PEX manifolds. 













 





mobile_bob

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Re: DIY water chiller - reading suggestions?
« Reply #97 on: August 29, 2021, 04:12:51 PM »
about 15 years ago or so, i rented an apartment that was a conversion of a 3 car garage
they took out the west bay and made the apartment.

being in tacoma, it had no A/C and for a week or two in the summer it got pretty miserable when things were in the mid 90's

at the time i would spend late into the evening working on my 55 chevy with the doors open, and at night the outside temps would drop to around the upper 50's to maybe 60 deg F.

i noted how cool the garage stayed during the day all closed up, while the apartment baked.

so i would close all the drapes on the west side of the apartment, and open the kitchen door which lead out into the shop area, and set up a little box fan to draw in the cooler air. 

that much cooler concrete slab would take up the heat from the apartment, and i noted rather than being 95 degree's at around 5pm each afternoon, it would only get up to about 80 degree's, which was a huge help.

we lived there for 3-4 years and each summer i cooled that place in the same manner

so i think your system is going to work fabulously!

and am looking forward to reports on how it is working out.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #98 on: August 29, 2021, 04:23:12 PM »
https://www.esmagazine.com/articles/92538-engineering-for-high-altitude

As I expected, the condenser will suffer about 20% loss in performance at my elevation due to air density loss and fan efficiency loss. 


"For example, a fan rated for 20,000 cfm will move 90,000 pounds of air per hour at standard conditions, but only 72,000 pounds per hour at 6,000 ft. Additionally, the fan laws show that a given fan operating at constant speed will draw less power and develop less pressure at altitude in direct proportion to the ratio of air densities. Fan manufacturers offer software to predict operating characteristics of their equipment at non-standard conditions."

Since they designed in a water slinging fan, that would be my first thing to test.  Alas, this time of year I don't have the dry air that would really make that work well. 

mobile_bob

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Re: DIY water chiller - reading suggestions?
« Reply #99 on: August 29, 2021, 04:30:26 PM »
the hotter the air, the more water it can hold?  i think that is right
so the slinger system should work about as well as it would had the humidity been lower.

it gets humid as heck in this part of kansas, and i note that spraying the condenser sure drops the pressure and the compressor seems to appreciate the lower loads too. it makes less noise?

not very scientific, but i think there is something to it?

never considered the elevation and thinner air effect on the system, but it makes sense to me.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #100 on: August 29, 2021, 04:49:43 PM »
Bruce,
I know the 410 txv 12k units are out there. The local ac supply house assembles them from Sporlin
parts. The day I checked I watched my friend who works there look up the parts it would take
to assemble one.  He would have had to order the main body because they didn't have one that size
in stock. I was going to buy one and send it until they quoted me 180.00 plus tax. !!!!!

I will call Dometic tomorrow and see what they say. Their 12k water to air 410 heat pumps use txv valves.

Try water on the coil I think it will make a BIG difference.

I would go with the txv after you have tried the other things we have talked about. You may be happy
with what you have after a few "tweeks".

Metro 6/1 turning a ST 7.5 KW gen head
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BruceM

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Re: DIY water chiller - reading suggestions?
« Reply #101 on: August 29, 2021, 09:29:18 PM »
I tried an experiment today. The pressure started at 440 on the high side, 130 low side, same as yesterday, similar conditions.  I added water to the tray so the fan rim would pick it up as designed.  WOW, the pressures dropped to 355 psi high side and 120 suction.  It had little effect on the condenser outlet air temp, and air flow felt reduced, but it sure works, and continued to do so as long as I kept the tray filled so the fan water rim was in the water.  When the water runs low, the pressure climbs again. So adding a water feed/float valve might be one solution.  I did not test BTU performance, but I'm expecting it would improve as well. 

I also did some investigation then with a fast acting thermometer in a hand held anemometer.  The temperature on the air inlet at ground level was about 11 degrees  above ambient, about 98F.  I thought it might be condenser heat getting back to the inlet, so I turned off the compressor but left the fan on.  No real change.  I then tried chest vs ground level temperatures away from the unit but still with wind blocked by the shed.  What's happening is that the ground is heated by the sun, and radiating that heat upward near the ground.  It's less pronounced with more wind, but as wind slows near the ground I still see this solar radiant heating effect on air temperature.  I'm also getting the same heating effect as I go closer to the west facing wall, but just being close to the ground is problem.  There's no vegetation to insulate the earth.

Lots to consider; I didn't realize that radiant heat from the ground and close structures would have such a large effect on inlet air temperature. The built in water spritzing via fan rim cooling sure works, even though it was humid today from last nights rain.  I wish I had a source of demineralized water; I expect my well water would turn the coils into a mineralized mess.  My water is quite good for AZ but still pretty hard.

Apparently many window AC units use this fan ring/rim  in water trick to get rid of the evaporator condensate, while boosting performance.

I'm not sure what my best approach is, yet.





32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #102 on: August 29, 2021, 11:06:11 PM »
No......say it ain't so...............I did expect to see a change but not that much......
I do know that that compressor is much happier at 350 rather than 440.....did you get an amp
draw to see the difference ? I bet it fell off quite a bit.

One thing for sure, you won't catch rain water and use that.......you don't get any rain.......

Think you could use a filter of some sort to filter out the biggest part of the minerals ?
I use one of those big white canister filters on my home well. I change the filter every
couple of months. It does filter alot of crap out of my shallow well.

I know you will get it figured  out.........

Again.....GOOD JOB !!!!!




« Last Edit: August 29, 2021, 11:28:26 PM by 32 coupe »
Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

32 coupe

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Re: DIY water chiller - reading suggestions?
« Reply #103 on: August 30, 2021, 12:16:59 AM »


I see in my area many of the ac condensers are being mounted on welded aluminum frames.
They sell them at the supply house, I just never paid any attention. Don't need 'em on a boat !
Usually 18 to 20 inches off the ground. I do know in some areas they do that for fear of water rise.
Maybe there is more there than meets the eye. The units are usually on concrete slabs or parking
lots..........

Shade........if you can get enough cover for the worse part of the day.........morning and afternoon rays
are much easier on equipment than that 3 or 4 hours at "high noon)...........


Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

broncodriver99

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Re: DIY water chiller - reading suggestions?
« Reply #104 on: August 30, 2021, 12:39:01 AM »
Bob,

Yes, that is the formula for sensible heat.

Bruce,

Here are links to some valves that I found that should work. TXVs for AC have an equalizer line that needs to be connected to the suction. It can either be a flare joint or it is a cap tube that will have to have a hole drilled for it, inserted, and brazed in. Or, you can get a piece of 1/4" copper flare it on one end and use a flare nut and crimp the other end around the cap tube and braze it. Valves have a range so a 1.5 ton valve should work it will just be at the minimum limits of it's flow. You can just use reducing couplings or bushings to match your connection sizes if need be.

- 1 Ton Valves:

https://surpluscityliquidators.com/products/1-ton-thermal-expansion-valve-r410a-1.html?151557
https://surpluscityliquidators.com/products/1-ton-thermal-expansion-valve-r410a.html?173449#slide_172280

- 1.5 Ton Valves:

https://surpluscityliquidators.com/products/112-ton-thermal-expansion-valve-r410a.html?171039#slide_156891
https://surpluscityliquidators.com/products/thermal-expansion-valve-8.html?155762
https://surpluscityliquidators.com/products/15-ton-thermal-expansion-valve-38-odf-odm-r410a.html?179445
https://surpluscityliquidators.com/products/15-ton-thermal-expansion-valve-r410a.html?183639
https://surpluscityliquidators.com/products/112-ton-thermal-expansion-valve-r410a-3.html?183579
https://surpluscityliquidators.com/products/112-ton-achp-txv-kit-r410a.html?200538#slide_341529