kindly suggest cooling system for refrugerated water circulator

hi all
i am trying to develop an water chilling circulation device for one of the instrument we supply. the basic purpose is to circulate the chilled water through a glass coil condensor which has hot vapors in it.

the specification is as follows.

there is tank which contains 10-12 liters of water solution (70% water and 30% ehtylene glycol to prevent freezing) which is to be circulated through a silicon tube of 2 meters to a glass condensor which has evporating hot vapors in it and then back to the tank.
we have to maintain a temprature of -10 or -20 degree Celcius.

kindly suggest me the compressor type and capacity along with motor wattage, coil thickness and length and all other things which u think are important as basic configuration for the device.

i had seen in an uk based same device they have implimented rotary condensor, but when i asked to various engineers they said it is not successful so go for a basic one.kindly suggest the best possible which i can implement as its very urgent for me