DairyCo

Milk Cooling

Below we have explored some of the most widely used methods of milk cooling and highlighted the efficiency of using each method.

Bulk Tanks

Ice Bank tank (IB)

• Has a built in ice store that is used to produce chilled water for cooling the milk.
• The energy efficiency of ice based systems is poor compared to a Direct Expansion tank because of the extra heat transfer 'steps' involved.
• Ice can be made even when the milk does not need cooling.
  • This allows maximum benefits to be taken of cheap rate electricity tariffs. This reduces the running costs and compensates for lower efficiency of ice-based systems.

Direct Expansion (DX)

Direct Expansion tanks are smaller than Ice Bank tanks with the same milk holding capacity. This can reduce the need for building work when a tank is replaced.

• Cools the milk by placing it in direct thermal contact with the refrigerant.
• A Direct Expansion tank can be up to 50% more energy efficient than an ice bank tank.
• Cooling can only be provided where there is warm milk in the tank.
  • A Direct Expansion tank uses much more daytime electricity than Ice Bank tanks. This increases the running cost and reduces the benefits of higher efficiency.
  • Larger compressors are required than those with an Ice Bank tank. In rare cases the main electricity supply to the farm may need to be upgraded which can be expensive.

Ice Builders

This is a separate ice store which supplies chilled water to a plate heat exchanger. An ice builder is most commonly used in combination with a Direct Expansion tank. The benefits are:

• Where space is limited they can be located in a nearby room.
• Smaller compressors are required.
• Enable maximum benefit to be taken of cheap rate electricity.
• Lower milk cooling costs.