Horizontal Plate Freezer
- Most common of contact category
- Used for rectangular shapes and large flat surfaces
- Refrigerant mostly used is ammonia , through flexible hoses
- Shelves are moveable- able to pass refrigerant from one side to the other
- Plates move up and down
Process
- Refrigerant is used to flood the plates from outside reservoir
- Heat flows from the freezing product to colder refrigerant vaporizes at low pressure
- Liquid/vapor then flows via gravity/ or pump to external reservoir, where it separates
- Liquid then moves through freezer plates, vapor is pumped to compressor, pressurized to high side, it liquefies in the condenser and returned to low pressure reservoir
Vertical Plate Freezer
- Uses same plates, but installed vertically
- Developed 50 years ago by British
- Can be used for mince or semi-liquid products
- Freezing occurs, hot gas is pumped into plates, plates can then be pulled apart
- Rams eject the frozen blocks out of the top
Shelf Freezer
- Freezer plates are fixed as shelves
- Less expensive than horizontal freezer
- Freezing times are longer because contact is only made on the top
- Combination freezer– combo of cold air blast freezer over plate shelving
Contact Belt Freezer
- Belt can be cleaned by washing/drying equipment
- Air blast is common
- Brine sprays can be used as well
Process
- Fluid or wet products placed on steel belt
- Belt leaves tunnel and product pops off and falls into collector