hello all,
My name is Ryan im from Australia Sydney. I have been in the trade 10 years.
I am in the process of trying to figure out if the fluid in a receiver tank,is in a saturated state.
I have read a lot of forums on the subject and would like to get your feedback on my theory.
based on my observations on a low temp rack in a supermarket.
best example to use for this theory.
R404a,
ambient on roof where condensor is 73.4F/23C
SCP set@190psi/Approx 84.2 F/29 C
minimal fluctuation at time of testing, 188psi to 192psi - correct fan cycling maintained by E2 controller
plant room temp where receiver is 68F/ 20C (in a underground car park)
liquid temp entering tank at, 77F/25C (6inches from inlet) (constant temp with small fluctuations approx 1/2 a kelvin)
liquid temp leaving 78F/ 25.5C (6inchs from outlet)
pressure drop across tank from inlet to outlet 1 psi AND
inlet to start of drier core shell 1.2 psi (approx 1 and 1/2 ft away from outlet of tank WITH VERTICAL RISE)
pressures taken with calibrated fieldpiece gauges and cross checked contact probes,(against other sensors) which are insulated from abmient air.
only one out of 4 compressor running fully loaded
horizontal receiver tank, liquid enters from top, leaves at bottom (capacity approx 300 liters)
subcooled 5K
receiver tank sglass locations- middle of the vessel
liquid level in tank sglass, half full, fluctuations between the bottom of sglass and half full (i can always see the liquid.)
top of tank is slightly hotter than bottom by 1/2 Kelvin

i think the state of the fluid is subcooled at the bottom (bulk liquid) and at the head or interface of liquid to vapour (also above this interface) its in a theoretical saturated vapour state with nonequilibrium conditions occurring.
Thus the rise and fall of the liquid in the tank is not only from TXV opening and closing due to loads but also from the rate at which evaporation and condensation occurs.

I think this state occurs NOT by the increase of energy into the subcooled liquid
(ie we add sensible heat to a subcooled liquid to become a liquid with no subcooling, then add latent to cause a phase change to begin to a saturated liquid then saturated vapour)
but by the simpler process of evaporation, of a fluid in a closed/dynamic system with constantly uneven molecular kinetic energy levels occuring at the top of the liquid.
mostly from the liquid entering the tank causing different waves or splash patterns and the minor fluctuation of pressures and temps.
I would love to hear what you all think as everyone i ask here in Australia just thinks im an idiot for looking in to it too much. (The funny thing is i work for the largest refrigeration company in Australia.)