Strange TXV setup

[mad fridgie]

Sorry gentlemen, I have been away for a week (sales show, i was like a duck out of water)
Chef has shown that this is a critical charge working on a fixed orifice, regardless if the system is right or wrong. If he added more refrigerant then his fresh products froze. This shows that "most" but not all of the refrigeration effect in the chillers was produced by sensible cooling, which leads to real increased superheat. The superheat entering the compressor is further increased due to the suction liquid HX.
What seem to be upsetting the applecart is the full sight glass, If we assume that the sightglass is an aid to charging and not a definite method, then we could ignore the sightglass, then the system as charged is acting as one would expect. Critical charged system.
Adding more refrigerant will bring the TXV into play, either correct control if orifice is the correct size or some level of hunting if oversized, either way at this point we do not have a low enough superheat to close the valve.
There are no mystery pressure drops!
What is required is some form of reduction of heat transfer between the plates and the chiller boxes (to ensure product does not freeze)
A full compliment of refrigerant then can be added. At this point can you see if the valve seletion is correct.
I would add a suction accumulator, just as a measure of protection.
Insulating the bulb always a good idea, but at this stage has no real relevence.
I am with RLK use a number 2 orifice.
The number one goal of this system is to keep the products frozen and chilled, the system works as a critical charge.

[Gary]

Sorry gentlemen, I have been away for a week (sales show, i was like a duck out of water)
Chef has shown that this is a critical charge working on a fixed orifice, regardless if the system is right or wrong. If he added more refrigerant then his fresh products froze.

Apparently I missed the post where Chef said adding refrigerant froze the products?

[mad fridgie]

Apparently I missed the post where Chef said adding refrigerant froze the products?

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Frozen lettice

[Gary]

Page 1 , 37
Frozen lettice

He didn't say his lettuce froze when he added refrigerant. He said if all his plates got to -20C, then his lettuce would freeze.

Well... yeah

He just needs to shut the system down when the fridge/chiller is down to temp.

I see no evidence that the insulated shields are needed... but it wouldn't hurt.

[mad fridgie]

He didn't say his lettuce froze when he added refrigerant. He said if all his plates got to -20C, then his lettuce would freeze.

Well... yeah

He just needs to shut the system down when the fridge/chiller is down to temp.

I see no evidence that the insulated shields are needed... but it wouldn't hurt.

My iterpretation, chef can answer this one.

You can not simply shut down on temp, which of the 3 boxes are you going to use, also remember that they are eutectic plates in series, so you require prelonged run time at setpoint (to freeze the solution) Again he has managed to control the system (as far as the product goes) succefully for many years at the expense of the compressor.
By sheilding the plates, he can reduce the suction superheat (allowing the plates to drop in temperature) and increasing the life of the compressor. It also may give the advantage that the time between recharges can be increased (suspect freezer dependant.)