This operation is performed as follows in the current state of the art: the line is composed of a freezer (machine designed to cool a mix made in advance after having added a variable quantity of air depending on the recipe at a temperature called the proportioning temperature), tubing between this freezer and the proportioning machine, and therefore a proportioning machine that itself usually precedes a setting tunnel and packaging machines.
The freezer is started so as to work (freeze) the first mix quantities made in advance and these mixes are then sent to the proportioning machine through the tubing.
The first quantities cannot be proportioned because they are too soft and too liquid and they form a loss; attempts are made to recycle this loss later on in other installations under conditions that are not always satisfactory and often partial.
The purpose of this invention is to provide a means of reducing these start up losses.
An analysis of the phenomena involved during this start up operation shows that the main cause of losses is the quantity of product that has to be used to cool the tubing located between the freezer and the proportioning machine until the metal from which this tubing is made is cold enough so that bond conditions between the product and the tubing wall are such that proportioning is possible.
As it exits from the freezer, the temperature of the product is between −8° C. to −9° C. and 0° C. depending on the planned use of the product. The temperature of the tubing at the beginning of the operations is ambient temperature (18° C. or more). Therefore the solid mix melts as it comes into contact with the metal and flows too quickly, losing its consistency and making proportioning impossible until the tubing becomes sufficiently cold so that a bond is formed between the solid product mix and the metal, after a certain quantity of product has passed. The product can then be proportioned, but large losses have occurred.