Controlling temperature of a cryogenically refrigerated product

A method for controlling the temperature to which a product is chilled in a blender having a rotatable impeller adapted to be driven by an electric motor comprising the steps of selecting a predetermined temperature to which a batch of said product is to be chilled;

• introducing solid CO.sub.2 into said blender and into contact with said product;
• energizing said motor to mix said solid CO.sub.2 and said product together to thereby chill said product;
• sensing the actual temperature of said product and sensing the actual power drawn by said motor when the actual temperature of said product is reduced to said selected temperature, whereby said sensed power drawn at the selected temperature constitutes a predetermined power draw level;
• terminating introduction of solid CO.sub.2 upon sensing said selected temperature;
• removing said batch chilled to said selected temperature from said blender;
• introducing a further batch of said product and solid CO.sub.2 into said blender;
• sensing the actual power drawn by said motor upon energization thereof and mixing of said product and solid CO.sub.2 ;
• comparing said sensed power draw with said predetermined power draw level;
• and terminating said introduction of solid CO.sub.2 when said sensed power draw reaches said predetermined power draw level, whereby said product is chilled to said selected temperature.

Apparatus for controlling the temperature to which a product is chilled comprising blender means having an impeller therein;

• electric motor means adapted to drive said impeller;
• signal responsive means for selectively introducing and terminating a flow of solid CO.sub.2 into said blender with said impeller being effective to mix said solid CO.sub.2 and said product to thereby chill the same;
• the improvement comprising means for sensing the value of the electrical power drawn by said motor;
• analyzer means for comparing said sensed power with a predetermined power value and means for supplying an electrical signal to said signal responsive means upon the value of said sensed power exceeding said predetermined power value to terminate the flow of solid CO.sub.2 introduced into said blender.