Chilled Water

A 20mm OD copper tube 10m long would be about right. It can be bent or soldered with fittings to fit the shape of the container.

You have approximately 16,000 BTU/h with this unit. You didn't say anything about re-heating incoming water, so I assume it's a batch process?

Good luck.

1/2 ton cooling = 12000/2 = 6,000 BTU/h

Thanks, don't know where 16,000 came from.

Your idea is good but you have to consider the following ,.1.the pipe size especially the liquid line ,should not be too big ,to facilitate superheat and expansion.2.the suction pipe should not be too big also.The other issue is the expansion device.If you want to use TXT make sure you use the smallest possible size with adjustible orifice.If you chose to use destributers ,use the smaller capilleries .NB your expansion devise selection can guaratee the lifespan of your compressor and the smooth operation of your chiller ,On the issue of the evaporator,a softdrone copper pipe which is easy to bend by hand ,is ideal,dont use 90 degree elbows use a manual pipebender.

Thanks to all for the advices, to make it more clear I rephrase it as below.

I am cutting off the evaporator / indoor part of a split unit and planning to close it with copper coil and an expansion valve. This copper coill will be dipped in a storage of 300L water to cool that water to 20 degree C.

Another coil is dipped in the same storage tank to heat exchange, that circulates water with incoming temp of 35 degree C. Flow of water in this coil is 100L / H.

Since I am disconnecting the evaporator part from the circuit I wanted to connect same volume of 3/8" copper coil.

No scope to measure the volume physically.

Will it be 50cc approx ?

Hope I am more clear now.

Why go all that way, cutting and then replacing the existing evaporator with a copper pipe, coiled etc?

You can use the existing evaporator, removing it from the indoor unit and installing it in an enclosing box, pump the water to be cooled through the evaporator directly. You can circulate the water from your 300L tank through this evaporator box, and back into the 300L tank.

Since the existing evaporator is already sized to transfer heat from the AIR, it will still be efficient for water circulating/cooling. Building a new coil as you are planning will be much less efficient at first until you improve it by trial and error...

Stagnant water cannot effectively exchange heat with running refrigerant. Heat exchange rate is proportional to velosity of liquids. In your case most probably you will find coil freezing unless you are not using a heat exchanger with circulating water

The water needn't be stagnant.

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As long as the coil adding heat and the evaporator coil are positioned well, there should be plenty of circulation.

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As long as the evaporator coil allows vertical flow and is positioned in the upper portion of the tank to one side, and the coil adding heat is placed in the lower portion of the other side of the tank, unless the tank is a very awkward shape, or some form of barrier exists, natural circulation will occur.

After completing the evap coil make sure circulation of water over the coil to avoid freezing

What diameter is the existing suction tube to the compessor?