How i can design the pipes size and number for thermosiphon

How i can design the pipes size and number for thermosiphon solar water heater , the area of the solar collector 1.5 - 2 m^2

Solution

It depends on the rate of flow, which can vary.

The tradeoffs are: entrained air, noise, corrosion, energy transfer/pump energy.

Also whether you want to use water or some other liquid., ths would chane the thermal properties of the fluid and hence the heat transfer rate capability.

1/2 inch to 1 inch are usual for the pipe size., the solar system should work irrespective of the flow rate, which would depend on the dia of the pipe.

On the other hand, the total length of the pipe will introduce a friction effect and loss of head, so the vacuum of the siphon may not be sufficient to lift up the water to the height required in betwee the inlet and outlet. This factor is usually ignored in the usual calcualtions for home owners and DIY manuals. It would depend on the pipe size, the inner smootness, material etc.

Best.