Description of Blast and Fluid Bed Freezer
The blast freezer and fluid bed sections are contained, along with the fan and evaporator, inside an insulated cabinet. Access doors to both sections are fitted with observation windows and an electrically heated surround to prevent the doors from freezing in the closed position. Inside the cabinet, a fan with adjustable impeller transports air from the interior of the cabinet into the freezer ducting and through the evaporator tube bank where it transfers heat to the refrigerant.
The air, now reduced in temperature, passes trought he tray section which can be observed through a removeable perspex panel. It then changes direction and passes vertically up through the fluid bed section, back into the cabinet space where it is again circulated by the fan. The blast freezer section contains 5 trays on to which the food samples to be frozen are placed.
There is a facility for thermocouple sensor leads to pass into the ducting and through the cabinet wall so that freezing temperatures and rates can be monitored externally. There is a facility for a suitable anemometer to be inserted into the ducting to allow the air speed to be measured.