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friesr
21-08-2007, 08:24 PM
Looking at building this chiller out of old parts lying around. I am not a refrigeration guy but I have one willing to put this contraption together if I come up with some design specs. Hopefully you guys will help me out with that.
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I am needing a unit to maintain a 300 gallon water bath at 35 deg F. We add about 15,000 BTU of load to the water twice a day of which we relay on the thermal conductivity of the water and itís thermal mass to do most of the work. The max demand on the refrigeration would be on a once a week change of the water. Incoming water temp is about 55 deg F and would need to be at 35 within 4 hours.
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I found a picture of a home made chiller for an aquarium that gave me the idea but need it to get colder than an aquarium. I have a 1.5hp 18,000 btu R-22 condenser unit and need some help on how to size cooling side to get the necessary efficiency and contact time with the coil.
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The idea is to house the coil inside a 4 inch pvc pipe and flow the water across the coil fast enough to keep it from freezing up and slow enough to efficiently chill the water.
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Thanks in advance for your input.
Rod

Lowrider
21-08-2007, 10:32 PM
It's not that hard! Q=m*c*dT

For the rest get a refrigeration engineer to do the job!

friesr
22-08-2007, 02:18 PM
Great input!... :rolleyes:

Lowrider
22-08-2007, 09:22 PM
so no hardball then?

In my opinion a plate heat exchanger is a better option than the pvc bodging exchanger. You can buy one almost anywhere.

The reason I stated to get a ref tech is that working on a refregiration system is not that simple as it looks.
For instance the joints have to be able to withstand the pressures involved in the system, safety devices to be implemented and correctly placed and adjusted, a control device installed and adjusted!

So know you know why!

Then getting on:

To get started: 300 gallon is 1,14 m3 or 1140 liter, 35F is 1,6 dgr C, 55F is 13 dgr C, 15000 BTU is 4,4 kWh, 18000 BTU is 5,28 kWh.

Then to the formula! Q=m*c*dT

Q is heat to be added or removed in kW
m is mass flow in kg/s or for water in l/s
c is specific heat, for water 4,2 kJ/kg*s
dT is the temperature difference

You can do the math now!?

The MG Pony
23-08-2007, 04:31 AM
http://cgi.ebay.com/New-Brazed-16-Plate-Stainless-Steel-Heat-Exchanger_W0QQitemZ220141464811QQihZ012QQcategoryZ20598QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

16 plate HX

friesr
24-08-2007, 12:32 AM
Would the ***** flow thru this or would I pump something like propylene glycol thru it? If the later, I will still need some chilling coil and then another tank and pump.

aquaticeco.com/index.cfm/fuseaction/product.detail/iid/22376/cid/4395

The MG Pony
24-08-2007, 02:16 AM
It can be used direct expansion and the water flows through the other set of ports.

How do you intend to pull of this project lacking such basics?

A FPHX is not rocket science!

friesr
24-08-2007, 02:32 PM
[quote=

How do you intend to pull of this project lacking such basics?

quote]

You are right, when it comes to refrigeration, my knowledge is very basic. Like i said, i have a refrigeration guy that will put this all together from me once i have some design specs. That is why I am here asking you experts.

The MG Pony
26-08-2007, 10:40 PM
Ah Ok. Well the plate Hx's are the best in most ways one can look at it. and ebay you can get them cheap. To further expand I recoment you place a good filter on the water side of the plate Hx to avoid fouling.

dogma
08-11-2008, 05:43 AM
Looking at building this chiller out of old parts lying around. I am not a refrigeration guy but I have one willing to put this contraption together if I come up with some design specs. Hopefully you guys will help me out with that.
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
I am needing a unit to maintain a 300 gallon water bath at 35 deg F. We add about 15,000 BTU of load to the water twice a day of which we relay on the thermal conductivity of the water and itís thermal mass to do most of the work. The max demand on the refrigeration would be on a once a week change of the water. Incoming water temp is about 55 deg F and would need to be at 35 within 4 hours.
<o:p></o:p>
I found a picture of a home made chiller for an aquarium that gave me the idea but need it to get colder than an aquarium. I have a 1.5hp 18,000 btu R-22 condenser unit and need some help on how to size cooling side to get the necessary efficiency and contact time with the coil.
<o:p></o:p>
The idea is to house the coil inside a 4 inch pvc pipe and flow the water across the coil fast enough to keep it from freezing up and slow enough to efficiently chill the water.
<o:p></o:p>
Thanks in advance for your input.
Rod



Are you trying to build a still??
An old temprite works well so i'm told





dogma