T40 Blast Chiller not running properly

[fixbear]

I don’t know what the suffix numbers of you compressor relate to, Depending on that it’s real BTU’s may be as low as 28,000. The T-40 manual that I’ve seen calls for 45 lb’s. I know that that compressor has to be special to cover both medium and low temp applications. So it will have a bit smaller bore than a standard one. Now I understand why they cost $28,000.

[fixbear]

<div> 245 Liquid or so, bout -23*F evaporating over 103-106 * condensing
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So what is the water temp’s into and out of the condenser?

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[olivero]

Started another freeze cycle after defrosting.

14 minutes into it.

Box Temp -11*F

Coil Temp -16*F

Suction: 8.2 PSI (-32.4*F)

SLT: 44.1*F

SH: 76.5* (At compressor)

Liquid side: 261.2 PSI (107.0*F)

LLT: 103.9*F

SC: 3.1*

25 Minutes into freeze cycle.

Box Temp: -17*F

Coil Temp: -19*F

Low side: 7.2 PSI (34.2*F)

SLT: 11.3*F

SH: 45.5*F

High Side: 261.7PSI (107.1*F)

LLT: 103.4*F

SC: 3.7*

40 minutes into freeze cycle.

Box Temp: -21*F

Coil Temp: -22*F

Low side: 7.1 PSI (-34.4*F)

SLT: 8.7*F

SH: 43.1*

High Side: 250.7 PSI (104.1*F)

LLT: 101.9*F

SC: 2.2*

What do you guys think?

[olivero]

1 hour and 10 minutes into a freeze cycle.

Box temp is -22*F

Coil temp is -23*F

Low pressure: 7.1 PSI (-34.5*F)

SLT: -20*F

SH: 14.5*F

High Side: 246.7 PSI (102.9*F)

LLT: 101.2*F

SC: 1.7*F

Compressor discharge line right before it enters the condenser: 147*F (2 feet or so from the compressor discharge valve)

Condenser outlet is 102*F

Condenser water inlet to the condenser: 102*F

Condenser water outlet of the condenser outlet 103.2*F

[fixbear]

Why is you cooling water so hot? Whats the ambient of your cooling tower?

That’s were the capacity is lacking. Incoming water should be lower than 95F to come near capacity.

[olivero]

Fixbear,

Ambient around here is close to 100*F at the moment, there’s a large condenser outside with 3 fans mounted on the top of it.

There’s not really a cooling tower.

[fixbear]

If you have a 100 ambient, 103 is really good.

I recall from a year or so ago that you had a closed water recirculating system. That means a pump, expansion chamber above the heat ex changers, They are commonly referred to as cooling towers because they have to be above the other equipment they cool for head purposes.

[fixbear]

When it is real hot, if the humidity is below 70%, you can drop the water temp by adding a mist of water to the air just before the heat exchanger. Think evaporative cooling.

40 min into the freeze cycle with how many pounds of load? Flash freezer should be down to -40 in a hour.

Any high moisture product like meat or fish has to be flash frozen to protect texture. If the cells are frozen slowly, they burst and ruin the texture. Think mushy. If flash froze, The cells remain intact and the quality is very near fresh state.

[olivero]

Makes sense.

The above numbers were done with no load, just an empty box, or, it had 2 potatoes I put in there, but that was it.

The refrigerant temp would have to be lower to hit -40*F, I imagine -50*F at least to get a delta t where there’s a chance of making it that cold.

Low side would have to be barely above 0 PSI to make it.

[fixbear]

What is your suction pressure control cut out point?

And where was the leak?

[olivero]

Currently it’s set to around 4 PSI

Leaks were in the condenser outlet service valve and the suction service valve, fixed the packings, pressure test, vacuum, etc. All went well.

[fixbear]

Do you tighten and maintain the valve service caps and gaskets? I’ve seen more of them missing over the years than installed. The older metal ones had a copper seal gasket. Some of the newer plastic ones don’t do much except prevent ice from forming and stretching the packing. They also form a corrosion that sometimes makes very difficult to remove them. Same for the Schrader valves. I like the brass caps that are hex type. Next to that the brass knurled ones. Can’t even guess how many thousands of them I’ve replaced. The good valves for refrigeration have the green viton seal and stronger spring than automotive. Found many of them in systems over the years as well

[olivero]

Occasionally I do, I’m not very well frequented to them.

I added the Teflon seal repair whatever it’s called and that sealed it up.

[fixbear]

The problem is with the back seat. They are a tapered hard steel valve against a softer body. When back-seated tightly it close’s off the test port and the stem packing. But often they wear or get foreign material in them. The Rotolocks are not a problem to replace, but the receiver valves are usually welded on. I’ve seen many a compressor suction valve placed incorrectly so that the line is on the top. Water gets in them from condensation and late in the cycle it freezes. Every compressor cycle. This crushes the copper and can pull the flare out or reduce the capacity of the line. Line should be sides or bottom, never the top.