Submerged copper tube

[Peter_1]

Has anyone experience determining the needed copper coil lenght for a given capacity, fed by evoporating refrigerant, submerged in a tank of agitated water that has to cool down to just above freezing temperature of the water?

[headgasket]

Hi peter
Rough guess find the evap with the same rate and try and measure the length of pipe. I have worked on many homemade water chillers in my time they all work ok

[Peter_1]

It's not for me, someone asked me.
Heat load is 8 kW, how many copper pipes has to be submerged in the tank with clean, pumped water?

[Toolman]

We have built quite a few chiller tanks with copper coils , the length is important but not critical the longer the better . . The more surface area you have the better, just select the correct orifice for the capacity for the TX valve ( 8KW ) or the correct capillary diameter and length . Flow rate of the water you are cooling over the coil also has an effect .

This is site has all the technical details http://www.climaticcontrol.com/info/...c_12(rev1).htm

[Toolman]

We have built quite a few chiller tanks with copper coils , the length is important but not critical the longer the better . . The more surface area you have the better, just select the correct orifice for the capacity for the TX valve ( 8KW ) or the correct capillary diameter and length . Flow rate of the water you are cooling over the coil also has an effect .

This is site has all the technical details
http://www.climaticcontrol.com/info/...c_12(rev1).htm

[Peter_1]

Well, can you give a rough estimate what you've installed for a certain capacity?

[Peter_1]

Well, can you give a rough estimate what you've installed for a certain capacity?

[noddyhead]

Please find attached, put as much pipe as humanly possible. The more the better is agreed.

Regards

[Toolman]

Please find attached, put as much pipe as humanly possible. The more the better is agreed.

Regards

Ah the good old kelvi cheat sheet , you cant go wrong

[Peter_1]

Nodyhead, thanks very, very much. That's exactly what I was looking for.
And thanks also you took the time to scan this for me.
If I ever can help you, you know where you can find me.

Peter

[Dan]

Good job Nobby. I was looking for a similar table and couldn't find it. I had a picture of a bundle of tubing from a premix cooler and couldn't find it either. But it is as you say - as much as you can fit!

[Coolers]

When I've designed these type of coils in the past, I've always worked on the following:-

for 'still' water in a tank, a coil should give :- 20btu/hr per Sq Ft of Surface Area per degree FTD (The TD is the difference between the required finished water temp and the evaporating temp).

If the water is agitated, this can go up to around :-50 btu/hr per Sq Ft of Surface Area per degree FTD.

And if you're using 5/8" Copper, this has a surface area of 0.163625 Ft2 Per Foot of tube.

Always worked for me in the past


Good luck with it (Oh, and sorry it's in 'old money')

[Dan]

Hi Coolers. I haven't looked at the tables to compare your rule of thumb to see how it tracks, but your post had me revisiting thoughts that I had when Peter first posed the question. And that is my observation that the coils I see in post mix agitated water pools are iced up coils - providing near freezing water temperatures as the water forms ice on the coils and recirculates past this insulated barrier of ice.

So one should assume that ice formation is a necessary part of the load, I suppose? After that, the cooling is done with the latent melting and refreezing of the conditioned water, while the evaporator tubing operates at 10 to 15 degrees below freezing, with a cutout on a low pressure switch?

I like that term: "old money." I wish there were a way to just type in a number and say "psig" or deg C and have a magic bubble in parentheses show the recalculated number in bars or deg C, or vice versa. What with computers and all. Hint, hint, Dez.

Anyway, one could not have asked a simpler question than Peter's friend which drives me back into renewed attempts at understanding the basics of what we do and how we do it.