| ntact freezers are used for freezing in bulk meat, | | | | freezers is that it is a contact method of freezing, |
| offal, fish etc. There are two types: the vertical and | | | | and there is a reduction in energy usage over an air |
| the horizontal plate freezer. | | | | blast freezer. In an air blast freezer the head of fans, |
| 1. Vertical Plate Freezer (VPF) | | | | conveyors etc. has also to be taken into |
| The vertical plate freezer is manufactured with a | | | | consideration when designing a refrigeration plant |
| number of aluminium plates, vertically mounted, in | | | | Automatic Plate Freezer (APF) |
| which refrigerant is pumped through. The bulk meat, | | | | A variant of the HPF is an automatic plate freezer ( |
| etc. is placed in the gaps between the plates, and the | | | | Jackstone Autoplate ). A horizontal and vertical |
| product is frozen. Product thicknesses tend to be 50, | | | | freezer are a batch process, but an automatic |
| 75 and 100mm. | | | | contact freezer makes it possible to have a |
| The vertical freezer is ideal for producing a standard | | | | continuous process line. Automatic freezers are used |
| 100mm block, but offers no flexibility at all. A typical | | | | for freezing carton produce, i.e. prepared meals, etc. |
| product from a vertical is a meat block measuring | | | | APF's can be operated using conventional hydraulic |
| 1070 x 535 x 100mm, weighing 50kg. | | | | cylinders to lift and lower the stack of plates, or the |
| The vertical freezer is important in the food industry | | | | latest developments use screw jacks, with a much |
| as it enables rapid freezing of meat, which is then | | | | larger plate and a screw jack mounted on each |
| stored for future processing. | | | | corner. |
| 2. Horizontal Plate Freezer (HPF) | | | | It is interesting to comment on the comparison |
| Horizontal's mount the plates in a horizontal plane and | | | | between an air blast and a plate freezer from an |
| give a much greater flexibility, as various different | | | | energy point of view. A typical installation freezing |
| products can be frozen. Products between 25 and | | | | 1,000 Kg/Hr of meat products from 20 degree C to |
| 100mm are frozen on HPF's. | | | | -18 degree C - an air blast freezer would have a total |
| In both VPF and HPF, use is made of an extruded | | | | energy requirement of 170 kW, against an APF's |
| aluminium plate through which refrigerant is passed. In | | | | requirement of 132 kW. This results in a saving of |
| smaller machines the refrigerant would be Freon's, | | | | 22% in energy. Also the automatic plate freezer |
| normally on a direct expansion system; on larger | | | | would take up less factory floor space, but would |
| installations Freon's or ammonia, but on a pump | | | | not give the same degree of flexibility as that |
| system are used. the advantages of double contact | | | | experienced in air blast freezers. |