I've looked for a graphical representation of subcooling vs charge but I've not found one anywhere. I have found charts of cooling performance vs charge and charts of efficiancy vs charge. Both charts were normalized to 1.0 representing nameplate charge. Those charts show the fixed orifice system to be pretty critical for charge while the txv system is somewhat more forgiving of error.

Can anyone post a chart of subcooling vs charge, normalized to 1.0 as nameplate rating?