Milk chiller problem, pl help me

[muna]

Dear friends,

pl help me to find out the problem

we have installed 20tr glycol chiller with ammonia systems for chilling 10,000ltr/hr milk by alfa laval PHE.

we designed for chilling milk from 8 degree to 6 degree celcious(i.e 6degree drop)

but practically we give input milk is 6degree only
but we getting output milk temp is 3.5degr to 4 degree only(i.e is 2.5 degree drop only)
we gave the coolant side glycol temp is -5.5 degree to -6 degree
but we didn't get at least 5 degree drop

the milk chiller heat transfer area is 3.84m^2

pl anybody help me
whether the designed system is correct or not?

?????????

u can send ur idea to my mail box
munakp@gmail.com

im very much thankful to you,