Packo - Model RM/IB - Milk Cooler Tank
The ice-bank tank of Packo is the RM/IB model. Cooling of the tank's content is done by cooling water to 0 deg. Celcius by building an ice layer in a 'bath' full of water. Then this cold water is sprayed onto the inner tank, thus withdrawing warmth from the milk held by the inner tank. Ice bank tanks are easily recognized because of their square appearance. Because of the water resevoir in the bottom of these tanks, they seem to have a larger storage capacity than they actually have.
The ice bank principle has some specific advantages. Ice bank tanks can store very little amounts of milk just as easy as large amounts. In large direct expansion tanks, small amounts of milk will probably freeze because of the huge cooling capacity of the condensing unit. In ice bank tanks the condensing unit only cools and freezes water, the cold water that is acting as a cooling intermediate can never freeze the contents of the inner tank. Another advantage of the ice bank tank is the possibity to store cooling capacity in the water/ice mixture. When warm fluids enter a tank, an ice bank tank can cool this fluid much faster than a direct expansion tank.