York Screw Chiller How low will it go?????

I have an interesting problem that perhaps someone can give an answer to.

A client asked if he could use a York packaged chiller
(it is the one with the Frick screw mounted ,
upside down above the chiller I think it is a tdsh 163
short 200 hp),
was used for ac water chilling but now he wants to chill
a salt brine solution to -40 degress F.
Now before the questions.....
panel and starter were changed to accomodate the low
operating conditions, oil cooler was enlarged for the
extra heat of rejection, and misc other minor changes
such as a slide valve modify, r-22 is the refrigerant
Load is approx Xx tons with a flow rate of 450 gpm
in at -39 F and out at -43 F PD not a problem..
The system will drain and flush the brine after
each daily usage to alleviate damage to the copper
chiller tubes.

The original capacity was about 200 tons so the 30 or so tons should not be a problem
I believe there should be ample surface in both the chiller and the condenser to do the new capacity.

NOW YOU CAN FIRE AWAY. ANY INDUSTRIAL YORK GUYS OUT THERE THAT HAVE USED THIS UNIT FOR REALLY LOW TEMP??

I really look forward to your comments, This seems to be an excellent one for you Iceman...

Nothing like a challenge thrown down to get a persons attention...:D

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a salt brine solution

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• Calcium or sodium chloride???
  • Has anyone checked the material compatibility charts?
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    The system will drain and flush the brine after each daily usage to alleviate damage to the copper chiller tubes.

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I would be concerned about repeated exposure to air, can't say why but this bothers me.

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other minor changes such as a slide valve modify??

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• did this change the Vi?

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with a flow rate of 450 gpm

in at -39 F (-39.4C) and out at -43 F (-41.6C) PD not a problem..

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• Earlier you mentioned -40F (-40C), which is it?
• Is the tube velocity high enough to prevent laminar flow??
• Also, is the brine a liquid mix or flakes?

For some rough numbers:
A 163 short (open flash economizer) with R-22 will do about 30 Tons at -50F (-45.5C) suction and 100F (37.7C)condensing (no pressure losses allowed so this is already too low for capacity). Power = 111.3 BHP (~83 kW)

Without checking further...this looks like it could be trouble...

Iceman

glad you looked at this, your comments appear "well better then most"......

The reasons for the questions are for a legal problem of a client and his client.

The unit was using sodium chloride brine, no flakes.
The vi (this unit for york, has a fixed vi setting) has been modified to handle the long vi needed
so the hp - amp draw was below the force unload

The heat transfer velocity seems to be in the turbulent range my old company was a heat exchanger builder.
We feel the compatability could be a problem, but if
drained and flushed as noted it would negate the problem.
-40 F but -40 c is the same thing .....

So any more thoughts oh yes we got it to -28 F but the oil temp went high and shut down. They had not changed out the oil cooler at that time.

best to you..

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The unit was using sodium chloride brine, no flakes.

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The reason I asked about the flakes is that I have seen some problems with tube plugging when the solution is not mixed properly. And/or, shut down for some intervals. If the brine is not mixed correctly and completely, the flakes come out of suspension.

I have also seen some problems when the chiller tubes are periodically opened to atmosphere. Of course these were carbon steel tubes in ammonia systems, but I'm a little concerned the repeated flushing with clean water may accelerate tube sheet corrosion. Who knows what will happen to the copper tubes.

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The heat transfer velocity seems to be in the turbulent range

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If the copper tubes are enhanced surface the turbulent region for the Reynolds number may have to be higher than prime surface.

If I remember correctly a Reynolds number at or slightly above 10,000 may not be sufficient to get the most benefit from the tubes.

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we got it to -28 F but the oil temp went high and shut down

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What type of oil cooling are you using? water-cooled PHE??

If the evaporating temp. is -40C, then you might be able to get away with 30 Tons of cooling capacity if the chiller U value compensates for the lower load. Since the surface area is fixed, I would suspect you can run with a smaller approach temperature to get the 30 Tons.

The big "maybe" is the film coefficient for the brine. That is the driver.

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The reasons for the questions are for a legal problem of a client and his client.

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That's enough to make the hair on your neck stand-up. :eek:

It sounds like someone said no problem to changing this over to LOW temperature brine, and now they are trying to solve the problems.:confused:

I just remembered something else.

The chiller tubes will be undergoing regular expansion and contraction due to the daily temperature changes. Ambient to very cold, and then warmed up again with the clean water rinse.

The tube material compatibility may be a secondary issue if the tubes pull out of the tube sheets.:o

Normal design practice for an application like this would be to use an expansion joint in the shell.;)

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Originally Posted by bruceboldy

tdsh 163 short 200 hp),
was used for ac water chilling but now he wants to chill
a salt brine solution to -40 degress F.

Now before the questions.....
panel and starter were changed to accomodate the low
operating conditions, oil cooler was enlarged for the
extra heat of rejection, and misc other minor changes
such as a slide valve modify, r-22 is the refrigerant
Load is approx Xx tons with a flow rate of 450 gpm
in at -39 F and out at -43 F PD not a problem..
The system will drain and flush the brine after
each daily usage to alleviate damage to the copper
chiller tubes.

The original capacity was about 200 tons so the 30 or so tons should not be a problem
I believe there should be ample surface in both the chiller and the condenser to do the new capacity.

NOW YOU CAN FIRE AWAY. ANY INDUSTRIAL YORK GUYS OUT THERE THAT HAVE USED THIS UNIT FOR REALLY LOW TEMP??

I really look forward to your comments, This seems to be an excellent one for you Iceman...

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This is something hard to understand :confused: (for me, please)

-why to change panel and starter if your Condensing Pressure cP is still 14 bar - problem for motor is not suction but condensing pressure

-why to enlarge oil cooler if you reduce cooling capacity? -what is extra heat of rejection?

-what about ECO port

-what about Vi if you are going to do this in one stage?

eT= -40C, eP=1.05 bar = 2.05 gauge pressure
cT= +38C, cP=14,59=14.6 bar = 15.6 bar gauge pressure

= cP/sP (14.6+1.0/1.049+1.0= 15.6/2.05= Vi=7.60 :confused:


-Sodium chloride NaCl (kitchen salt) you can use down to -9C otherways you should use CaCl2/water solution (calcium cloride) down to -45C, but then you have a problem with material (you can use titanium heat exchanger and cast iron or plastic pipes) and not copper type. Definitely system must be flooded becuse CaCL2 is extremely corrosive even to SS material.

Maybe I miss something :confused:

Best regards,

Josip :)

josip

the software in the York panel forces you to change the panel. Once you change the panell you have to change the starter, it is interlocked to the panel.

The high heat load compression requires the larger oil cooler.

The Vi was re cut to match the high compression ratio vs simple water cooling.

Just intersted in the comments of the group about this equipment. and yes the legal comments refer to a money issue ( they always do it seems.

The tubes are a problem but the flow rate is ok for the new operation. The fluid is cacl2 not sodium chloride as noted earlier. and he was aware of the corrosion concerns.

Thanks for the intersting observations, and any other comments are welcome, depositions are not for another month!!!!!! Oh yes it was not my idea i am just gathering info...

You need 2 stage compressor for this!And R22 isnt best choice too.

Renato

Hi,
Tne Frick screw compressor can go down to -40F only the capcity will be reduced. It has aselection program that compressor can reach these temp. But if it is using a shell and tube it can't because the lowest temp it can reach is -8C(17.6F). you have to replace it with plate heat exchanger so you can put it down to -40F

David, when did York start using the code paks (believe that is what they were called) down to -40 dF leaving.

I'd be concerned with the whole project. I guess you are selling against this if you are still at the same company?

Corrosion is a real issue and the brine system needs to be pressurized with a nitrogen pad in my opinion.

I had run across them selling then rated down to about 0 dF leaving and no lower. The compressor can easily run at the conditions noted, but not very efficiently.

Send me a PM if you can.

ken

Sounds like a insurance claim/battle waiting for a court hearing. I would recommend at least a 2 stage ammonia system with a size large flooded PHE evaporator designed for the application, "google" the word Temper as they supply a -40c solution that is half friendly and stable at low temperatures. Legally check your insurances if any advise previously given, failing that change name and leave town.
Cheers Magoo

Most of my concerns about this project are related to the evaporator. -40°F is much below the design temperature of this unit and this can cause huge problems or even injures people. The reason for that is, that the strenght of steel rapidly decreases when the temperature drops to low and this affects integrity of the whole unit. Please refer to the nameplate of pressure vessels before you do something creative to them.