Refrigeration question.

[BrewinLou]

We are currenly replacing our brewery chiller with a much larger model. Our walkin cooler has two very old compressors one of which has not worked in years and never will again, the other is about to die. I have heard of brewers converting coolers from freon to glycol.
My question is concerning where do I cut in the line in front or behind the expansion valve. The copper tubing coming out of the refrigerant distributor looks very small. What psi is freon pumped at? Will a glycol system pump hard enough?

Thanks for any and all help..

[Moonlight]

If you cut the line, the refrigerant will escape into the atmosphere and give us all more cancer. Your refrig tech can save it safely.
You cannot use glycol in the same lines. It will not transfer enough heat.

[BrewinLou]

I have a refer guy who will reclaim the freon already lined up. I am already planning on running 1" insulated pvc all the way to the blowers in the cooler and back to the chiller. So no I will not be using the same lines.

[Moonlight]

I would be surprised if the diameter of the ex-refrigerant lines in the blowers would be large enough to handle the flow rate of glycol you need to keep your box cold enough.

[BrewinLou]

The super heat line in is half inch, at the exchanger it divides into ten eighth or so inch lines that run into the loops. The return is an inch at least. I am going to reverse that and have the inch going in and the smaller lines returning. You raise a good point. One unit is completely dead so I am going to blow some water through it to see what kind of flow rate I get. What psi is freon pumped at?

[Beersmith]

I would also be skeptical of converting an evaporator that uses refrigerant over to glycol. However, they do make evaporators specifically to run glycol. If you post your question on the Refrigeration Q&A Forum here, I'm sure someone from Pro Refrigeration (the moderator) will have a good answer for you.

[BrewinLou]

I am no newbie but today I can not find the Refrigeration Q A forum. How do I navigate to it?

[Jephro]

http://www.probrewer.com/vbulletin/forumdisplay.php?f=96

[jimvgjr]

Hey Joel,

There are several issues with converting refrigerant coils for use on a glycol system. You have mentioned one of the biggest issues, the ability to get enough glycol flow through the coil to enable an adequate heat exchange between the room air and the glycol. You need to remove the expansion valve and create a new inlet manifold to get the maximum flow through this coil as possible- I would also consider calling the coil manufacturer and see if they could advise you on this. It might take some time re-piping, but it is definitely doable.

Assuming you are able to get enough flow through this coil, now we need to consider how the refrigerant coils are sized. A typical refrigerant Coil is sized to operate on a 20 F TD (temperature difference), meaning that if your desired room temperature is 40 F, the coils is designed to operate with 20 F Refrigerant. When I specify glycol coils for a brewery, I size the coils for a 10 F TD. This is because most breweries will operate with a 27 to 30 F Glycol Temperature. To operate at this lower TD requires more surface area in the coil (bigger coil). So unless your refrigerant coils were oversized, you will probably be light on surface area on your converted coils.

Another thing to consider is the extra capacity this will place on your chiller system and if you have a single compressor chiller system you are placing a lot of eggs in this one basket.

One more concern is that refrigerant coils will have a nice coating of refrigerant oil within the copper lines. Even if you have a contractor come out and reclaim the refrigerant, there will still be oil residue that we don't want to get into your glycol system. Before connecting the refrigerant coil into your glycol loop, I would set up a little circulation pump and flush this coil out with a mild detergent to break down this oil and clean out the coil.

These are just a few things to keep in mind, it can be done though. I will add any other thoughts too and look forward to hearingfrom other forum members.

It sounds like you might have a coil that you can do some testing on, I would give it a shot and see how much heat you're able to exchange. Please feel free to give me a call with any questions or comments, I would be happy to help out anyway I can.

Good Luck,

Jim

Jim VanderGiessen Jr.
General Manager
Pro Refrigeration Inc.
Tel 253.735.9466 ext 203
Fax 253.735.2631
jimvgjr@prorefrigeration.com
www.prochiller.com

[BrewinLou]

http://www.probrewer.com/vbulletin/forumdisplay.php?f=96

Hmmmm refrigeration filed under ingredient. I will be trying to work that out in my head for a while.


"I size the coils for a 10 F TD"

The units in our walkin are older Bohn blowers. The Model is not listed on the Bohn website. But looking at the models that air defrost all are currently 10 F. Ours also have a lot more coils then the one pictured. So we shall see.

Thanks everyone...

[dast]

Hi,
Be aware that the PVC piping have its lowest operating limit at 32 F and you are probaly running your glycol at 20 to 27 F. So some different material options are: Copper, COOL-FIT ABS and COOl-FIT ABS Plus (pre-insulated COOL-FIT ABS)

Best Regards,

Dan Stromberg

Georg Fischer LLC
2882 Dow Avenue
Tustin, CA 92780

714-368-4196