Thermodynamic system, machine comprising the thermodynamic system and thermal treatment method

A method for thermally treating a liquid or semi-liquid food product, comprising:

• A) providing a machine for making liquid or semi-liquid food products, the machine comprising:
• a thermodynamic system for cooling or heating a first container containing a liquid or semi-liquid food product, comprising a circuit employing a heat exchanger fluid, including:
• a compressor including a compressor inlet for the heat exchanger fluid and a compressor outlet for the heat exchanger fluid;
• a first heat exchanger, having an outlet and an inlet, the inlet connected to the compressor outlet;
• a first expansion element connected to the outlet of the first heat exchanger;
• a second heat exchanger thermally connectable with the first container and which has an outlet and an inlet connected to an outlet of the first expansion element;
• a return duct including an inlet portion connected to the outlet of the second heat exchanger and an outlet portion connected to the compressor inlet;
• a temperature reducing device configured for reducing a temperature of the heat exchanger fluid, connectable with the circuit for receiving at least a portion of the heat exchanger fluid, including a device inlet and a device outlet, and configured to reduce the temperature of the heat exchanger fluid flowing between the device inlet and the device outlet, the device outlet being flowingly connected to the compressor inlet or inside the compressor;
• a regulating valve configured for regulating the flow of the heat exchanger fluid traversing the temperature reducing device between a minimum flow configuration and a maximum flow configuration;
• a controller operating on the regulating valve to drive the regulating valve;
• wherein the controller includes a measuring device adapted to detect a triggering parameter, the controller being configured to control the regulating valve for regulating the flow of heat exchanger fluid traversing the temperature reducing device as a function of a value of the triggering parameter;
• a processing unit comprising the first container and a stirrer mounted inside the first container;
• to rotate inside the first container;
• wherein the thermodynamic system is thermally connected with the processing unit, the second heat exchanger being thermally connected with the first container to exchange heat with the liquid or semi-liquid food product contained in the first container;
• placing the liquid or semi-liquid food product inside the first container;
• B) turning on the compressor to convey the heat exchanger fluid along the circuit of the thermodynamic system of the machine to perform a thermodynamic cycle for transferring heat to or from the liquid or semi-liquid food product inside the first container;
• C) regulating the flow in the temperature reducing device to a value greater than zero in order to cool the compressor.