What is the function of flash gas after the txv?

Flash gas is the portion of refrigerant that evaporates instantly as it passes through the refrigerant control orifice/cap tube/TXV. As it evaporates it lowers the temperature of the remaining liquid to the evaporator temperature without actually removing any heat from the system. Loss can be as high as 12% and with this loss of effective use of refrigerant it is important to keep the flash gas to a minimum.