hello every buddy

i want to upgrade my 50 ton brine chilling plant ( glycol 50 % ). i am going to give external cooling unit for sub cooling R 22 in super feed PHE ( brazed type ) it may be possible i will cool down R 22 at - 10 or -15 oC. can it is work ? or i need to change my expansion valve ? or only super heat adjustment needed ?
my expansion temp. is -30 0C with PHE & 70 m3 flow of brine

experts please help me.

& thanks in advance