Multi-circuit evaporators utilizing a thermostatic expansion valve (TXV) will have a refrigerant distributor connected to the outlet of the TXV to ensure the refrigerant leaving the TXV is fed equally into each circuit.
As the refrigerant leaves the TXV it is in a saturated state — a mixture of the liquid and vapor. The mixture is mostly liquid, approximately 75 percent liquid to 25 percent vapor by weight; however, the vapor occupies much more volume, and the two components are moving at different velocities. Because of the relationship, without a distributor, unequal amounts of refrigerant would enter each of the circuits. This would lead to some of the circuits receiving mostly liquid, possibly causing TXV hunting and floodback problems, and some of the circuits being starved for refrigerant.