DairyCo

Plate Heat Exchanger

In addition to being used along with an ice builder, a Plate Heat Exchanger (PHE) can be used with mains or borehole water to provide the first stage of milk cooling without using any electricity. If the water goes to waste it is cheaper to use electricity to cool your milk especially if you are on a mains water supply. Borehole water may be notionally free but it still needs to be disposed of.

Typical reuses include:

• Drinking water for your cows
• Parlour wash down

A mains/borehole water PHE should cool your milk by at least 10 degrees and preferably 15/20 degrees. If this is not the case then:

• Check the flow-rate of water. It should be a minimum of 10 litres/min and preferably 20 litres/min.
• There should be a solenoid that turns the water on when the milk pump is running. Check that it allows the water to continue flowing for 10-20 seconds (water overrun time) after the milk pump turns off.
• Check if it is possible to reduce the milk flow-rate by adding a simple butterfly valve.

You should aim for a ratio of water used to milk cooled of at least 1:1. As long as water is not wasted the higher the ration the better. However, do not do this by simply changing the water overrun time, as increasing it to more than 20 seconds will deliver next to no additional cooling.