Chilling Methods (Parts 2)

2. Moving Air

• versatility
• applicable to products of irregular shapes
• faster cooling as air speed increase

    2.1 Batch Air Cooler

    2.2 Continuous Air Cooler

• designed to produce even air velocity
• refrigeration capacity can be varied
• products are chilled through conveyer or continuous rack of trays
• cooled air is distributed either horizontally or vertically

    2.3 Wet air / bank cooling

• designed to overcome dehydration of product
• saturated wet cooled air
• more economical
• reduce weight loss
• great chilling efficiency
• large space is required for ice storage and operation

     

3. Direct contact

• heat transfer is based on direct of between product and metal surface

   3.1 Plate heat exchange

   3.2 Jacketed heat exchange

• cool the liquid in jacket vessel 
• cooling medium are circulated through the jacket of the vessel or through coil immersed in liquid
• vessel are provided with agitator to improve heat transfer
• low heat efficiency. Vacuum closed vessel reduce cooling time

4. Heat exchanger

   4.1 Belt heat exchanger

• effective for thin products
• continuous process
• easy cleaning
• reduce evaporation loss

   4.2 Continuous heat exchanger

5. Immersion / spray

• product are dipped into cold liquid
• high rate heat exchange
• reduce dehydratioon
• cool water or brine solution is used
• cold liquid can also be spray into food