Milk Cooling Tank - Direct Expansion Models (DX)
Operation
The direct expansion method of milk cooling, whereby milk is cooled by coming into direct contact with the evaporator (Cooling plates) is one of the most popular methods of milk cooling within Australia.
The horizontal construction is space saving and the efficient evaporator ensures quick trouble free milk cooling, coupled with the agitator the milk is evenly stirred ensuring optimal heat exchange and prevention of freezing.The agitator doubles to expedite the efficient cleaning via the rotojet cleaning powerball. All internal surfaces are smooth and thus there are no bacteria traps.
What is a “Direct Expansion” (DX) Pac Cool milk tank?
The direct expansion system is the most common form of refrigeration used in milk cooling both in the Australian and world markets.
A refrigeration compressor or unit pumps liquid refrigerant too the stainless steel cooling plates (evaporators). The evaporator is a twin skin stainless steel arrangement with a cavity between the two stainless plates. The internal skin of the evaporator has the milk or load that contains the heat while the other side incases the refrigerant that passes through the entire evaporator.
Upon entry the refrigerant which is at a much lower degree of temperature removes the excess heat that is within the milk. The refrigerant carries this heat back to the refrigeration compressor where the cycle restarts thus sending super cool refrigerant back to the milk cooling tank evaporators.
Direct expansion is exactly what the name means, refrigerant used directly to cool via the stainless steel evaporators.
Uses for “Direct Expansion” Pac Cool milk tanks
For farmers that are small in milk production too intermediate, the direct expansion method is the most efficient and cost effective form of cooling. Larger producers of milk need to look further towards the on call glycol chiller system utilizing the direct expansion system or the full DIB glycol systems.
Direct expansion milk cooling tanks work on the 60% of total volume of the tank. Compressors are designed and sized to be able to cool the milk load at 60% in one milking.
The Australian standard of direct expansion is - 22>4 degrees @ 60% volume over 3.5 hours cooling time.
In normal milking a farmer would be cooling his/her milk while the milk enters the tank. So a properly designed and sized direct expansion milk cooling tank should be cooled down to 4 degrees and turned off by the time the farmer has left the shed after milking.
