Sub cooled r22 still flashing?

[Drew]

Room seems happier. Super heats have improved. Suction is up to -27 C hp at 42C. Will be checking to see whether this is ok. The sight glass on the receiver shows between 40 and 45% . Sucooling 8c. Adding the refrigerant has helped, BUT I still have a flashing sight glass. Maybe not as much though.
Raising the hp back to what might have been its original design pressure could have influenced texv capacity. The assumed need to keep the hp down to protect the compression ratio and the relative lack of refrigerant could have created high superheats . The system is happier with these improvements , but still not understanding the sub cooled thing with saturated vapor in the sight glass?

If we take a refrigerant cylinder half full of refrigerant liquid it would be saturated. Even if we cooled it it would stay saturated. It would not become sub cooled because the temp would drop with the pressure. Liquid can only become sub cooled if their is no vapor present? So how in this #+*^% sight glass can I have sub cooled liquid and saturated gas?

[Rob White]

The system is happier with these improvements , but still not understanding the sub cooled thing with saturated vapor in the sight glass?

If we take a refrigerant cylinder half full of refrigerant liquid it would be saturated. Even if we cooled it it would stay saturated. It would not become sub cooled because the temp would drop with the pressure. Liquid can only become sub cooled if their is no vapor present? So how in this #+*^% sight glass can I have sub cooled liquid and saturated gas?

In principle you are correct.

Liquid that is subcooled is not in contact with the vapour.

The trouble with subcooling is it is not as straight forward as that,
even at degree level there is debate about how subcooled liquid flows
through a system.

I can explain it in laymans terms and it works for me, ask me to go deeper
though and my brain freezes up because it does not work on pure science.

So my understanding of liquid is.

Subcoold liquid can be in contact with vapour if it is flowing.
The second it becomes stationary it is saturated and the reason
is because the flowing liquid has temperature levels in it. As liquid
flows through a pipe it flows in thermoclimes? (thermocline?), basically
it flows at different temps through the pipe and therefore it can still be
classified as subcooled because the liquid is below the saturation temp.

I think it is something to do with a bloke called Reynolds (Reynolds number)
look him up on google and he will confuse you with the science of fluid mechanics.

http://en.wikipedia.org/wiki/Reynolds_number

It is a lot more complicated than that but that works for me.

Regards

Rob

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