Glycol systems?

Can anybody outline in laymans terms how a glycol system works and why they are used in a system that needs to hit -40?? The system is in a corrosion testing chamber.

Thanks in advance

basically a wet system with antifreeze, your glycol circuit will transfer heat from a fan coil unit to the evap shell.
by using glycol there could be a dry cooler that will give free cooling by rejecting heat from the glycol to the ouside air - free cooling, also the use of an actuator will give close control.

This system uses a cascade refrig system to get to the -40c. I take it this is one refrig system to cool another?

sorry im full of questions, this glycol cascade is all new to me!

if cascade then the evap of the histage will cool the condenser of the low stage, an intercooler
http://www.google.co.uk/imgres?hl=en...9,r:5,s:0,i:85

Thanks monkey! thats a great link there!

RE forum strikes again!