Liquid receiver

[US Iceman]

...on the other hand liquid cannot enter the evaporator at all in a DX operation

Sure it does. There is about 85% of the entering liquid which is atomized into droplets after the TXV which enters the evaporator coil. This is where the evaporator capacity comes from in the first place. The balance (+/-15%) is the flash gas created during the expansion process, if the liquid temperature is warmer than the evaporating temperature.

If the liquid temperature entering the evaporator is lower than the evaporating temperature, the liquid will not boil.

How can TXV capacity be adjusted on the fly between summer and winter?

You don't. And I'm not suggesting you adjust the TXV's from summer to winter.

The valves have to be selected for the amount of subcooling that may be found. A selection that meets both operating criteria.

In a DX system designed for subcooling (which is a good thing to prevent or reduce the flash gas in the liquid lines) the valve capacity must be corrected for the amount amount of subcooling that will be seen.

The subcooling increases the valve capacity.