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Another Refrigeration question. Cold Plate liquid level?


Fusion

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My cold plate (brine/glycol) in the fridge freezer seems to be only 2/3 full. How much of an air gap is needed and can I top it up? Im pretty sure it is a glycol water mix.

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Yes should be filled up to the height of the bung. (should be about a inch down from top of tank aprox)

From memory 20% comes to mind ( glycol to water)

But the percentage sets the freezing point so google it if no one here knows

Mine worked heaps better when I filled it up.

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My cold plate (brine/glycol) in the fridge freezer seems to be only 2/3 full. How much of an air gap is needed and can I top it up? Im pretty sure it is a glycol water mix.

 

Ah that's handy I needed to ask the same question! Ta. :thumbup:

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Dont just fill it.

The mix depends on what temp you wish to achieve. The tank should freeze - notjust be cold. The change of state (from liquid to ice/frozen) is what stores the most energy. The right mix will freeze to a solid just before the freezer turns off, and then take A LOT longer to melt/warm up than a liquid taken down to the same temperature. Means less running of the freezer is required, and more time between...

 

The more gylcol, the lower the freezing point...

 

The perfect level in the tank is when it has almost reached the top when frozen

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Thanks IT. Mine was very green so I topped it up with distilled water and left the top off ran the fridge and got down to -8C and still no freezing on the inside. I ran out of time but old rub a drop of the solution between the fingers test feels very concentrated. I have a 12V Danfos compressor so am not aiming for sub arctic temperatures :-)

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no prob! Syphon out some fluid and replace it with water - a bit at a time, until you finally get a mix that freezes at your desired temp, and you will find the efficiency of the unit will really improve :D

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Exactly what I was intending to do :-)

 

I already think I know the answer but what Temp should I aim for.

 

The Fridge / Freezer unit is bench top access 900mm deep 900 across & 400mm Wide. I follows the shape pf the hull. Its effectively a triangle of approx 160 liters. Last year lined the inside with 2/3 of a sheet of foam reducing the capacity by about 50 liters. The main objective was to reduce the depth and remove the requirement to use BBQ tongs to retrieve lost pack of butter that had fallen to the bottom.

 

The Cold Plate is 400mm x 400mm x 75mm about 10 liters and is located half way down the 900 x 400 face.

 

I have 3 areas in the unit. The bottom is frozen = below zero. The middle is beer and wine 3 degrees. The top is veg and bread and the widest part of unit ranging from 5 - 7 degrees furthers from the cold plate.

 

 

I am thinking my target freeze at about -5 Degrees ?

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Not sure how well that will work - usually two seperate cabinets. Food safety orgs usually say about -20c for freezer - but that is long term storage. Fridge about 4c I think. I guess you'll have to experiment!

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Correct, I should have stated stuff freezes at the bottom but not a long term freezer option.

I removed 1.5 letters with a 25ml syringe at lunch time and topped it up with distilled water.

I will see what it looks like tonight.

 

How well will it mix by its self?

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