Thermodynamic system and machine comprising said system

Abstract

A thermodynamic system for cooling or heating at least a first container containing a food product of the liquid or semi-liquid type, comprising a circuit using a heat exchanger fluid, preferably a transcritical fluid, having at least: a compressor provided with a first inlet and a first outlet for the heat exchanger fluid, and a second inlet and a second outlet for the heat exchanger fluid; a first heat exchanger comprising an inlet for a heat exchanger fluid connected to the second outlet of the compressor and an outlet for the heat exchanger fluid, the first heat exchanger further comprising an inlet for a working fluid and an outlet for the working fluid; a second heat exchanger associated with at least the first container; an inlet branch for the heat exchanger fluid extending from an outlet for the heat exchanger fluid of the first heat exchanger to an inlet of the second heat exchanger; an outlet branch for heat exchanger fluid extending from an outlet of the second heat exchanger to a first inlet of the compressor; and a control and drive unit.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of machines for the preparation of liquid or semi-liquid food products.

[0002] In particular, the present invention relates to a thermodynamic system and a machine for liquid or semi-liquid food products comprising the system of the invention. BACKGROUND

[0003] In the industry of machines for liquid and semi-liquid products such as ice cream, pastries or the like, it is known to thermally process (i.e. cool and / or heat) the base product to implement a predetermined recipe and make the finished liquid or semi-liquid product.

[0004] Various heating systems of thermodynamic type are known, which allow the thermal processing (heating or cooling) of the product in the container to change its food / sensory characteristics.

[0005] In fact, a feature of professional ice cream machines is the need to cool and bulk freeze the ice cream mixture and pasteurize it to ensure optimal hygiene conditions.

[0006] Therefore, the operating cycle of an ice cream machine comprises different steps: a step of cooling and making the ice cream; and a pasteurization step comprising heating, maintaining and cooling the ice cream.

[0007] Moreover, when the ice cream is cooled again after pasteurization, bulk freezing is required.

[0008] Ice cream bulk freezing is traditionally carried out by using a combination of a vapour compression refrigeration cycle and mechanical stirring.

[0009] While the pasteurization process is carried out by injecting hot gas into the evaporator or by heat pump operation of the vapour compression cycle. It is also known that most thermodynamic cooling systems allow the cooling of the container by means of a thermodynamic circuit operating on a heat exchanger fluid and comprise a pair of exchangers (evaporator and condenser), a compressor and a throttling element, all using a heat exchanger fluid.

[0010] Typically, such systems use a hermetic or semi-hermetic compressor comprising a casing which encloses the compression element and the electric motor acting on the refrigerant fluid.

[0011] Ice cream machines operate by using a refrigeration cycle of the heat exchanger fluid as refrigerant.

[0012] To date, fluorine-containing gases (F-gases) have been used as refrigerants, among which, for example, HFOs (hydrofluoroolefins), fluorinated hydrocarbons forming the fourth generation of fluorinated cooling gases, are widely used.

[0013] The ideal coolant should have certain characteristics, which include ensuring high energy efficiency, allowing low system installation and maintenance costs, ensuring as little environmental impact as possible, non-toxicity and non-flammability.

[0014] Therefore, the choice of technology and coolant should be carefully considered in terms of market sector, type of application, different legislative contexts, variations in installation and operating costs over time, and future developments, in particular in terms of product availability. It is therefore worth considering that some gases, which are currently available at low cost, could be subject to substantial price increases and / or to quotas due to mechanisms provided by regulations on fluorinated gases.

[0015] It is easy to imagine that the theme of energy efficiency not only affects the operating costs of the system, but also has a non-negligible impact on environmental sustainability. Therefore, the transition from HFO refrigerants to natural refrigerants is underway.

[0016] One of the refrigerants defined as natural is CO2, which, due to its reduced impact on the environment, seems to be the best solution even if the required system design is very expensive due to the high pressures involved. Therefore, CO2 is a viable option only for new systems.

[0017] In fact, this gas of natural origin has certain characteristics suitable for the design and construction of a refrigeration system.

[0018] This gas is abundant in nature and is a waste of several industrial processes, so it is very low cost and has a reduced impact on the environment compared to the most widespread refrigerants; in fact, it has an ozone depletion value (ODP) of zero and a contribution to global warming (GWP) of 1.

[0019] Finally, it is a non-toxic, non-flammable gas with optimal thermodynamic and heat exchange properties.

[0020] The main drawback of using CO2 in a system is its low critical temperature and the high operating pressure when used.

[0021] In fact, the refrigeration cycle of machines using traditional fluids is a vapor compression cycle between 1.3 and 1.7 bar, while the cycle used by CO2 machines operates between 15 and 90 bar, so its use requires a specific conception of the system. SUMMARY

[0022] In this context, the technical task of the present invention is to propose a thermodynamic CO2 system that overcomes the above-mentioned drawbacks.

[0023] In particular, the aim of the present invention is to provide a thermodynamic system that can allow the heat treatment of liquid or semi-liquid food products and ensure its operation under optimal conditions.

[0024] It is therefore another object of the present application to provide a thermodynamic system which allows to increase the efficiency of the heating cycle.

[0025] It is another object of the present application to provide a thermodynamic system which allows to maintain sufficiently high pressure and temperature of the heat exchanger fluid, while managing the heating step with increased efficiency.

[0026] The present application also relates to a machine for manufacturing liquid or semi-liquid food products.

[0027] The technical task and the specific objects are substantially achieved by a thermodynamic system and a machine comprising one or more of the technical characteristics set out in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0028] Further features and advantages of the present application will become better apparent from the indicative and therefore non-limiting description of a preferred, but not exclusive, embodiment of a thermodynamic system, as illustrated in the accompanying drawings, in which:

[0029] - Figure 1 a schematic view of a possible first embodiment of a thermodynamic system according to the present application is shown;

[0030] - Figure 2 a schematic view of a possible second embodiment of a thermodynamic system according to the present application is shown;

[0031] - Figure 3 a schematic view of a machine for liquid or semi-liquid products is shown, comprising the thermodynamic system shown in the previous figures;

[0032] - Figure 4 a quantitative trend of the temperature values reached by the mixture during the pasteurization step is shown;

[0033] - Figure 5 a quantitative trend of the pressure values reached at different positions of the system during the pasteurization step is shown. DETAILED DESCRIPTION

[0034] The thermodynamic system according to the present application is indicated in Figures 1-2 by the number 1, which will be indicated in the following as system 1, for the sake of simplicity of description.

[0035] This system 1 is suitable for a machine 30 for the thermal processing of liquid or semi-liquid, hot or cold food products, such as ice cream, soft ice cream, yogurt, chocolate, jelly, soup and other similar products.

[0036] In particular, the present application relates to a system 1 for cooling or heating at least a first container 11 of food products of the liquid or semi-liquid type.

[0037] According to the present application, the system 1 for cooling or heating at least a first container 11 containing a food product of liquid or semi-liquid type comprises a circuit using a heat exchanger fluid. Preferably, this circuit uses a transcritical type heat exchanger fluid.

[0038] The system 1 has at least:

[0039] - a compressor 2 provided with a first inlet "I1" and a first outlet "U1" for the heat exchanger fluid, and with a second inlet "I2" and a second outlet "U2" for the heat exchanger fluid;

[0040] - a first heat exchanger 4 comprising an inlet 4a for the heat exchanger fluid and an outlet 4b for the heat exchanger fluid.

[0041] The heat exchanger 4 is connected to the second outlet "U2" of the compressor 2 and is configured to allow heat exchange between the heat exchanger fluid discharged from the second outlet "U2" of the compressor 2 and a working fluid, which is preferably water (or, alternatively, air, or in any case any heat exchanger working fluid).

[0042] The first heat exchanger 4 also comprises an inlet 4c for the working fluid and an outlet 4d for the working fluid;

[0043] - a second heat exchanger 5 associated with at least the first container 11;

[0044] - an inlet branch 35 for the heat exchanger fluid, which extends from the outlet 4b for the heat exchanger fluid of the first heat exchanger 4 to the inlet 5a of the second heat exchanger 5;

[0045] - an outlet branch 36 for the heat exchanger fluid, which extends from the outlet 5b of the second heat exchanger 5 to the first inlet "I1" of the compressor 2;

[0046] - a control and drive unit 8.

[0047] It is noted that the first container 11 can be of any type, such as a cylinder, a tank, etc.

[0048] According to one aspect of the present application, the system 1 also comprises:

[0049] - a first pressure sensor 28 configured to generate a pressure signal indicative of the pressure of the heat exchanger fluid flowing between the second outlet "U2" of the compressor 2 and the inlet 4a of the first heat exchanger 4;

[0050] - a regulating device 7 for regulating the flow rate of the working fluid flowing towards the first heat exchanger 4 at the inlet 4c. Moreover, the regulating device 7 is operatively activated via the control and drive unit 8 depending on the pressure data obtained from the first pressure sensor 28.

[0051] The pressure switch 24 acts as a safety element, interrupting the operation of the compressor 2 if the pressure (for example detected by the pressure sensor 28) exceeds a predetermined deactivation value (for example, a value between 120 and 140 bar, more preferably a value between 125 and 135 bar).

[0052] The control unit 8 is configured to activate the compressor 2 if the pressure (for example detected by the pressure sensor 28) drops below a predetermined activation value (for example, a value between 90 and 110 bar, more preferably a value between 95 and 105 bar).

[0053] According to another aspect of the application, the system 1 comprises a bypass branch 12 and a bypass valve 13.

[0054] The bypass branch 12 is arranged in parallel with the bypass valve 13, positioned along the outlet branch 36 downstream of the second heat exchanger 5, so that when the bypass valve 13 is not activated, the heat exchanger fluid enters the bypass branch 12.

[0055] The bypass branch 12 has a second element 14 for reducing the pressure, configured to convey the heat exchanger fluid at the outlet 5b of the second heat exchanger 5 directly towards the first inlet I1 of the compressor 2, which has already reduced its pressure.

[0056] The regulating device 7 for regulating the flow rate of the working fluid entering the heat exchanger 4 comprises a valve (preferably an electronic valve or, alternatively, a mechanical valve).

[0057] It is noted that this valve is a proportional valve (i.e. with multiple regulation positions, thus allowing different orifices to be obtained).

[0058] Moreover, when activated, the regulating device 7 for regulating the flow rate of the working fluid entering the first heat exchanger 4 allows the working fluid to flow in the first heat exchanger 3 itself through the inlet 4c.

[0059] In other words, the first heat exchanger 4 is fed with the working fluid which flows through the regulating device 7, which acts as a proportional regulator of the flow of the working fluid by means of PID control through the readings of the first pressure sensor 28, in order to maintain a constant pressure in the cooling step.

[0060] Therefore, it is noted that the first pressure sensor 28 is configured to generate pressure data representative of the pressure drop between two points of the system, in particular between the second outlet "U2" of the compressor 2 and the inlet 4a of the heat exchanger fluid of the first heat exchanger 4.

[0061] Furthermore, the system 1 also comprises a thermostatic valve 10 arranged along the inlet branch 35, downstream of the first heat exchanger 4, with respect to the direction of flow of the heat exchanger fluid in the inlet branch 35.

[0062] The thermostatic valve 10 can be of the electronic type, or alternatively of the mechanical type.

[0063] The thermostatic valve 10 is operatively activatable by means of the control and drive unit 8, to regulate the load loss of the heat exchanger fluid, so as to control the evaporation pressure in the second heat exchanger 5, which in use defines an evaporator.

[0064] In other words, when activated, the thermostatic valve 10 allows the flow of the heat exchanger fluid towards the second heat exchanger 5, through the inlet 5a thereof.

[0065] For the purposes of the present description, it is also noted that the term activation valve or deactivation valve means that the control and drive unit 8 is considered to act on the valve, so as to promote the opening or closing thereof.

[0066] According to one aspect, the system 1 also comprises first monitoring means 15c for monitoring the temperature of the heat exchanger fluid flowing in the inlet branch 35.

[0067] The first monitoring means 15c are arranged upstream of the inlet 5a of the second heat exchanger 5, with respect to the direction of flow of the heat exchanger fluid in the inlet branch 35.

[0068] The first monitoring means 15c are configured to provide temperature data of the heat exchanger fluid in the inlet branch 35, in particular at a position between the thermostatic valve 10 and the inlet 5a of the second heat exchanger 5.

[0069] According to one aspect, the system 1 also comprises second monitoring means 15d for monitoring the temperature of the heat exchanger fluid flowing in the outlet branch 36.

[0070] The second monitoring means 15d are arranged downstream of the outlet 5b of the second heat exchanger 5, with respect to the direction of flow of the heat exchanger fluid in the outlet branch 36; the second monitoring means 15d are configured to provide temperature data of the heat exchanger fluid downstream of the second heat exchanger 5.

[0071] According to another aspect, the system 1 further comprises a second pressure sensor 29 arranged along the outlet branch 36 downstream of the second monitoring device 15d, configured to provide pressure data of the heat exchanger fluid downstream of the second heat exchanger 5.

[0072] The regulation of the thermostatic valve 10 is carried out according to the temperature data of the first and second monitoring devices 15c, 15d and the pressure data of the second pressure sensor 29, so as to evaluate the temperature gradient and the corresponding pressure upstream and downstream of the heat exchanger 5.

[0073] Furthermore, according to an embodiment, the system 1 further comprises:

[0074] - a temperature sensor 15e configured to provide to the control and drive unit 8 temperature data representative of the temperature of the heat exchanger fluid entering the first inlet "I1" of the compressor 2;

[0075] - a temperature sensor 15a configured to provide to the same control and drive unit 8 temperature data representative of the temperature of the heat exchanger fluid entering the second inlet "I2" of the compressor 2.

[0076] According to another aspect of the present application, the system 1 further comprises a third heat exchanger 3 connected to the first outlet "U1" of the compressor 2 and to the second inlet "I2".

[0077] The third heat exchanger 3 is configured to allow the heat exchange between the heat exchanger fluid and a working fluid, preferably water.

[0078] The heat exchanger 3 comprises an inlet 3c for the working fluid and an outlet 3d for the working fluid.

[0079] It is noted that, in order to regulate the flow rate of the working fluid entering the third heat exchanger 3 via the inlet 3c, there is an electronic valve 16, which can be activated by the control and drive unit 8 regulated by the data output from the temperature sensor 15a.

[0080] According to another aspect, the system comprises a bypass valve 13, which is operatively activated by means of the control and drive unit 8, to allow the flow of the heat exchanger fluid to the first inlet "I1" of the compressor 2.

[0081] The bypass valve 13 is arranged along the outlet branch 36 downstream of the second heat exchanger 5, with respect to the direction of flow of the heat exchanger fluid in the outlet branch 36.

[0082] The bypass valve 13 is arranged in parallel with the bypass branch 12, so that, when the bypass valve 13 is not activated, the heat exchanger fluid flows into the bypass branch 12, with the second pressure reduction element 14 operatively associated with the bypass branch 12.

[0083] The second pressure-reducing element 14 is used to reduce the pressure of the heat exchanger fluid entering the first inlet "I1" of the compressor 2, while maintaining the high pressure of the heat exchange fluid flowing through the second outlet "U2" of the compressor 2, since it is a CO2 system and therefore operates at high pressure values.

[0084] Preferably, the bypass valve 13 is controlled to completely close or completely open the bypass branch 12, inhibiting or allowing the circulation of the heat exchanger fluid within the bypass branch 12, and therefore inhibiting or allowing the subsequent flow in the second pressure-reducing element 14.

[0085] In other words, in order to reduce the pressure of the heat exchanger fluid entering the first inlet "I1" of the compressor 2, the bypass valve 13 is closed, sending the entire flow into the second pressure-reducing element 14, thus creating a pressure and temperature jump.

[0086] It is noted that the cooling of the heat exchanger fluid occurs due to the pressure jump created by the second pressure-reducing element 14.

[0087] In addition, the temperature sensor 15e continuously monitors the temperature of the heat exchanger fluid entering the inlet "I1" of the compressor 2, in order to maintain sufficient superheating, so as not to fall into the saturation vapor curve.

[0088] In order to have the necessary superheating, when it is necessary to increase the superheating, the bypass valve 13 is activated intermittently to vary the pressure jump.

[0089] In other words, the temperature of the heat exchanger fluid entering the first inlet "I1" of the compressor 2 is reduced by flowing through the second pressure-reducing element 14 and is continuously monitored by the temperature sensor 15e.

[0090] Therefore, it is clear that thanks to the innovation of the bypass branch 12, even using the hot gas cycle, the temperature of the components of the compressor 2 is always kept low.

[0091] Advantageously, when the bypass valve 13 is not activated, the bypass branch 12 is configured to extract the heat exchanger fluid in the outlet branch 36 from the second heat exchanger 5 and, after having subjected it to a corresponding pressure / temperature reduction, to send it to the first inlet "I1" of the compressor 2

[0092] Thanks to its relatively low temperature, the heat exchanger fluid at the inlet of the compressor 2 extracts thermal energy from the hottest components of the compressor 2, causing a reduction in the temperature of the compressor 2, i.e. its cooling, thus reducing the thermal stress to which the compressor 2 is subjected.

[0093] According to another aspect of the present application, the system 1 comprises a hot gas branch 6 for implementing a hot gas thermodynamic cycle.

[0094] The hot gas branch 6 is configured to convey the heat exchanger fluid from the second outlet "U2" of the compressor 2 towards the inlet 5a of the second heat exchanger 5.

[0095] According to Figure 1 the description of the system 1 shown in

[0096] The selective closing element 17 is operatively associated with the hot gas branch 6 and is configured to close and open such hot gas branch 6 to inhibit or allow the circulation of the heat exchanger fluid therein.

[0097] The first pressure reduction element 20 is always operatively associated with the hot gas branch 6 upstream of the selective closing element 17 with respect to the direction of flow of the heat exchanger fluid in the inlet branch 35.

[0098] Further aspects and details of the system 1 will now be described.

[0099] In particular, it is noted that the outlet branch 36 has along its path a regenerative heat exchanger 9 configured to define a heat exchange section between the heat exchanger fluid flowing along the inlet branch 35 and the heat exchanger fluid flowing along the outlet branch 36.

[0100] According to a preferred embodiment, the system 1 further comprises a dehydration filter 18 which allows to ensure the cleanliness of the heat exchanger fluid, facilitating the removal of any impurities accumulated by the fluid during the cooling or heating cycle, in particular when crossing the compressor 2.

[0101] As shown in detail in the attached Figure 1 The dehydration filter 18 is arranged along the inlet branch 35, between the outlet 4b of the heat exchanger fluid of the first heat exchanger 4 and the inlet 5a of the second heat exchanger 5, as shown in detail in the attached

[0102] In practice, Figure 1 The system 1 in

[0103] Therefore, the implementation of the reduction of the temperature of the heat exchanger fluid in Figure 1 will now be described, which can also be implemented separately in the system 1.

[0104] In the first phase of the cooling configuration, the heat exchanger fluid is cooled using a working fluid which enters the compressor 2 through the heat exchanger 3, which functions to cool the working fluid before it is processed in the second compression stage, the working fluid being preferably water.

[0105] The flow rate of the working fluid entering the inlet 3c of the heat exchanger 3 is regulated by the electronic valve 16 as a function of the temperature of the working fluid flowing through the outlet 3b of the compressor 3 and detected by the temperature sensor 15a.

[0106] Preferably, the flow rate at the inlet 3c of the heat exchanger 3 is regulated by the electronic valve 16 in an intermittent manner; in short, once the temperature sensor 15a detects that the predetermined temperature (for example 35°C) is reached, the electronic valve 16 is activated.

[0107] According to a further aspect, the electronic valve 16 is deactivated when the temperature detected by the temperature sensor 15a is lower than the predetermined temperature by a predetermined hysteresis value (for example 0.5°C).

[0108] After this first step, the heat exchanger fluid is processed by a second compression stage.

[0109] The heat exchanger fluid flows through the inlet 4a of the heat exchanger 4 and is delivered into the heat exchanger 4 through the second outlet "U2" of the compressor 2.

[0110] The heat exchanger 4 further cools the heat exchanger fluid by means of a working fluid, preferably water, which enters the heat exchanger 4 through the inlet 4c.

[0111] The flow rate of the working fluid flowing into the inlet 4c of the heat exchanger is regulated by the regulating device 7 comprising an electronic valve.

[0112] In this step, the regulating device 7 for regulating the flow rate of the working fluid entering the heat exchanger 4 is activated to allow the working fluid to flow in the heat exchanger 4 itself.

[0113] In other words, the flow rate of the working fluid is regulated by the regulating device 7 as a function of the pressure data generated by the first pressure sensor 28, which indicates the pressure of the heat exchanger fluid flowing between the second outlet "U2" of the compressor 2 and the inlet 4a of the heat exchanger fluid in the heat exchanger 4.

[0114] The heat exchanger fluid flows through the outlet "U2" of the compressor 2, which is discharged from the second stage of the compressor 2, completely delivered into the heat exchanger 4, since the selective closing element 17 is closed to inhibit the circulation of the heat exchanger fluid within the hot gas branch 6.

[0115] The heat exchanger fluid flowing through the outlet 4b of the heat exchanger 4 proceeds along the inlet branch 35, crossing the dehydration filter 18 and the regenerative heat exchanger 9, which is used to further cool it.

[0116] Afterwards, the same heat exchanger fluid reaches the thermostatic valve 10, which is activated to allow the heat exchanger fluid to flow towards the inlet 5a of the heat exchanger 5.

[0117] According to the temperatures monitored at the inlet 5a and at the outlet 5b of the heat exchanger 5 by the first and second temperature monitoring devices 15c, 15d and according to the pressure monitored by the second pressure sensor 29, the thermostatic valve 10 is regulated by increasing or decreasing the load loss to maintain a specific evaporation pressure.

[0118] The heat exchanger fluid on the outlet branch 36 thus flows out from the outlet 5b of the evaporator, crosses again the regenerative heat exchanger 9 and crosses the bypass valve 13, which is activated to allow the heat exchanger fluid to flow towards the first inlet "li" of the compressor 2.

[0119] In other words, after crossing the bypass valve 13, the heat exchanger fluid reaches the inlet "li" of the first stage of the compressor 2, before the inlet "I2" where there is a temperature sensor 15e configured to provide the control and drive unit 8 with temperature data of the heat exchanger fluid entering the first inlet "li" of the compressor 2.

[0120] By contrast, the following describes Figure 1 the embodiment illustrated in figure 5 for raising the temperature of the heat exchanger fluid, which can also be implemented separately in the system 1.

[0121] The system 1 described below does indeed allow to increase the temperature and the pressure of the heat exchanger fluid.

[0122] In the initial heating step, it is necessary to heat the heat exchanger 4 to ensure that the working fluid accumulated in this heat exchanger 4 maintains a sufficiently high temperature to allow to increase the pressure of the system 1 without keeping it cold and inert.

[0123] To this end, it is necessary to perform a brief switching step in which the thermostatic valve 10 is completely opened to allow the heat exchanger fluid to flow towards the heat exchanger 5, while the selective closing element 17 is still closed to prevent the heat exchanger fluid from circulating in the hot gas branch 6.

[0124] At these moments, the regulating device 7 for regulating the flow of working fluid is not activated to inhibit the flow of working fluid in the heat exchanger 4. It should also be noted that the temperature output from the heat exchanger 4 is monitored by the temperature monitoring device 15b.

[0125] Then, when the selective closing element 17 is opened, the thermostatic valve 10 can be completely closed and the heat exchanger fluid is conveyed from the second outlet "U2" of the compressor 2 into the heat exchanger 5.

[0126] It is noted that, in the initial heating step, the heat exchanger fluid is brought to the trans-critical phase before starting the next step.

[0127] In other words, during the heating step, at least one selective closing element 17 located on the hot gas branch 6 is open to allow the circulation of the heat exchanger fluid in the hot gas branch 6 and the regulating device 7 for regulating the flow rate of the working fluid entering the inlet 4c of the first heat exchanger 4 is inactive to prevent the flow of said working fluid in the heat exchanger 4.

[0128] In fact, the new flow of working fluid in the regulating device 7 and consequently in the heat exchanger 4 will cause a decrease in the temperature of the heat exchanger fluid.

[0129] The hot gas branch 6 must be calibrated so as to reduce the pressure by means of the pressure reduction element 20 so as to allow the desired increase in temperature on the second stage compression circuit, i.e. the circuit deriving from the second outlet "U2" of the compressor 2.

[0130] The bypass valve 13 is closed to reduce the temperature of the heat exchanger fluid flowing through the inlet "I1" of the compressor 2 so as to enter the first stage of the compressor 2 and further increase the temperature and pressure generated at the second outlet "U2" of the compressor 2, thus exiting the second stage of the compressor 2. Consequently, the entire flow rate of the outlet branch 36 is conveyed into the bypass branch 12, more specifically into the second pressure reduction element 14 on the bypass branch 12, which causes a jump in pressure and temperature.

[0131] Consequently, the temperature generated by the heat exchanger fluid at the first inlet "I1" of the compressor 2 is reduced and constantly monitored by the temperature sensor 15e.

[0132] In other words, the bypass valve 13 is inactive so that said heat exchanger fluid flows through the bypass branch 12 towards the first inlet "I1" of the compressor 2.

[0133] The bypass branch 12 is equipped with a pressure reduction element 14. As mentioned above, due to the peculiarity of the CO2 system, which is characterized by high operating pressures, it is necessary to reduce the pressure and temperature of the heat exchanger fluid before it re-enters the first inlet "I1" of the compressor 2.

[0134] Consequently, the branch 12 and the element 14 serve to efficiently manage the heating step, limiting the pressure values in the first inlet "I1" of the compressor 2.

[0135] In fact, analyzing the graph in Figure 5 , in which the trend of the pressure values of the different points of the system 1 during the pasteurization, i.e. heating step, is described, it is clear that the pressure values of the heat exchanger fluid close to the first inlet "I1" of the compressor 2 are lower than the pressure values of the heat exchanger fluid close to the second outlet "U2" of the compressor 2.

[0136] Moreover, the attached Figure 4The graph in the figure describes the temperature trend of the ice cream mixture contained in the first container 11 during the pasteurization step, i.e. the step in which it is brought to a temperature close to 100°C to ensure optimal hygiene conditions.

[0137] According to the present application, a machine 30 for manufacturing a liquid or semi-liquid food product is also defined, which comprises in combination:

[0138] - a processing unit 21 for manufacturing a liquid or semi-liquid food product, comprising at least one container 11 and a stirrer 23 arranged inside the at least one first container 11 to rotate inside the first container 11;

[0139] - a system 1 operatively associated with the processing unit 21,

[0140] - a second heat exchanger 5 associated with the at least first container 11 for exchanging heat with the product contained in the at least first container 11.

[0141] According to another aspect, the machine is an ice cream machine and the processing unit 21 is a batch freezing unit; moreover, the machine 30 is a pasteurizer and the processing unit 21 is a heating unit and / or a cooling unit.

[0142] It should be noted that, according to the present application, the thermodynamic system can be applied to any type of machine capable of thermally processing a liquid or semi-liquid product.

[0143] Advantageously, the system 1 according to the present application allows to overcome the above-mentioned drawbacks of the prior art.

[0144] Advantageously, a system 1 is provided which allows to allow the thermal treatment of a liquid or semi-liquid food product and to ensure its operation under optimal conditions.

[0145] Advantageously, a system 1 is provided which allows to increase the efficiency of the heating cycle.

[0146] Advantageously, a system 1 is provided which allows to maintain sufficiently high pressure and temperature of the heat exchanger fluid, while efficiently managing the heating step.

Claims

1. A thermodynamic system (1) for cooling or heating at least a first container (11) containing a food product of liquid or semi-liquid type, comprising a circuit using a heat exchanger fluid, preferably a transcritical fluid, said thermodynamic system having at least: - a compressor (2) provided with a first inlet (11) and a first outlet (U1) for the heat exchanger fluid, and a second inlet (12) and a second outlet (U2) for the heat exchanger fluid; - a first heat exchanger (4) comprising an inlet (4a) for the heat exchanger fluid connected to the second outlet (U2) of the compressor (2) and an outlet (4b) for the heat exchanger fluid (4), said heat exchanger (4) being configured to allow heat exchange between the heat exchanger fluid and a working fluid, said first heat exchanger (4) further comprising an inlet (4c) for the working fluid and an outlet (4d) for the working fluid; - a second heat exchanger (5) associated with said at least one first container (11); - an inlet branch (35) for the heat exchanger fluid extending from the outlet (4b) for the heat exchanger fluid of the first heat exchanger (4) to an inlet (5a) of the second heat exchanger (5); - an outlet branch (36) for the heat exchanger fluid extending from an outlet (5b) of the second heat exchanger (5) to the first inlet (11) of the compressor (2); - a control and drive unit (8); characterized in that it comprises: - a first pressure sensor (28) configured to generate a pressure data signal representing the pressure of the heat exchanger fluid flowing between the second outlet (U2) of the compressor (2) and the inlet (4a) of the first heat exchanger (4); - a regulation device (7) for regulating the flow rate of the working fluid entering the inlet (4c) of the first heat exchanger (4), said regulation device (7) being operatively activated via the control and drive unit (8) as a function of the pressure data signal. The working fluid entering the inlet (4c) of the first heat exchanger (4) is water, and wherein the regulation device (7) for regulating the flow rate of the working fluid entering the first heat exchanger (4) comprises an electronic valve. It comprises: - a thermostatic valve (10) located along the inlet branch (35) downstream of the first heat exchanger (4) with respect to the flow direction of the heat exchanger fluid in the inlet branch (35), said thermostatic valve (10) being operatively activated via the control and drive unit (8) to regulate the load loss of the heat exchanger fluid, thereby regulating the predetermined evaporation pressure in the second heat exchanger (5); ​ ​ ​ ​ ​ ​ 2. The thermodynamic system (1) according to claim 1, characterized in that ​ 3. The thermodynamic system (1) according to one or more of the preceding claims, characterized in that, ​ ​ - a bypass valve (13) located along the outlet branch (36) downstream of the second heat exchanger (5) with respect to the flow direction of the heat exchanger fluid in the outlet branch (36), the bypass valve (13) being operatively activated via the control and drive unit (8) to allow the flow of the heat exchanger fluid towards the first inlet (II) of the compressor (2).

4. The thermodynamic system (1) according to one or more of the preceding claims, characterized in that, comprising: - a first monitoring device (15c) for monitoring the temperature of the heat exchanger fluid flowing in the inlet branch (35), the first monitoring device (15c) being located upstream of the inlet (5a) of the second heat exchanger (5) with respect to the flow direction of the heat exchanger fluid in the inlet branch (35), the first monitoring device (15c) being configured to provide a heat exchanger fluid temperature data signal; - a second monitoring device (15d) for monitoring the temperature of the heat exchanger fluid flowing in the outlet branch (36), the second monitoring device (15d) being located downstream of the outlet (5b) of the second heat exchanger (5) with respect to the flow direction of the heat exchanger fluid in the outlet branch (36), the second monitoring device (15d) being configured to provide a heat exchanger fluid temperature data signal; - a second pressure sensor (29) positioned along the outlet branch (36) downstream of the second monitoring device (15d) and configured to provide a heat exchanger fluid pressure data signal; wherein the thermostatic valve (10) is regulated as a function of the temperature data signals from the first monitoring device (15c) and from the second monitoring device (15d) and of the pressure data signal from the second pressure sensor (29).

5. Thermodynamic system (1) according to one or more of the preceding claims, characterized in that comprising a temperature sensor (15e) configured to provide a temperature data signal to the control and drive unit (8) representative of the temperature of the heat exchanger fluid entering the first inlet (II) of the compressor (2).

6. Thermodynamic system (1) according to one or more of the preceding claims, characterized in that comprising: - a temperature sensor (15a) configured to provide a temperature data signal to the control and drive unit (8) representative of the temperature of the heat exchanger fluid entering the second inlet (I2) of the compressor (2); - a third heat exchanger (3) connected to the first outlet (U1) of the compressor (2) and to the second inlet (I2) of the compressor (2); the third heat exchanger (3) being configured to allow heat exchange between the heat exchanger fluid and a working fluid, the third heat exchanger (3) comprising an inlet (3c) for the working fluid and an outlet (3d) for the working fluid; - an electronic valve (16) connected to the inlet (3c) for the working fluid entering the heat exchanger (3) and activatable via the control and drive unit (8) to regulate the flow of the working fluid entering the third heat exchanger (2).

7. Thermodynamic system (1) according to any one of the preceding claims, characterized in that comprises a dehydrating filter (18) located along the inlet branch (35) between the outlet (4b) of the heat exchanger fluid of the first heat exchanger (4) and the inlet (5a) of the second heat exchanger (5).

8. Thermodynamic system (1) according to one or more of the preceding claims, characterized in that comprises: - a hot gas branch (6) for performing a hot gas thermodynamic cycle, configured to convey the heat exchanger fluid flowing from the second outlet (U2) of the compressor (2) to the inlet (5a) of the second heat exchanger (5); - at least one selective closing element (17) operatively associated with the hot gas branch (6) and configured to close and open the branch (6) to prevent or allow the heat exchanger fluid to flow therein; - a bypass branch (12) configured to convey the heat exchanger fluid flowing from the outlet (5b) of the second heat exchanger (5) directly to the first inlet (II) of the compressor (2).

9. The thermodynamic system (1 ) according to one or more of the preceding claims, characterized in that, comprises: - a first pressure reduction element (20) operatively associated with the hot gas branch (6) upstream of the selective closing element (17) with respect to the direction of flow of the heat exchanger fluid; - a regenerative heat exchanger (9) configured to define a heat exchange portion between the heat exchanger fluid flowing along the inlet branch (35) and the heat exchanger fluid flowing along the outlet branch (36).

10. - Thermodynamic system (1) according to claim 8 when depending on claim 3, characterized in that, The bypass branch (12) is provided in parallel with the bypass valve (13), so that when the bypass valve (13) is not activated, the heat exchanger fluid flows into the bypass branch (12), which has a second pressure reduction element (14) operatively associated with the bypass branch (12).

11. Thermodynamic system (1) according to any one of the preceding claims, characterized in that The system (1) is able, in use, to switch between a heating configuration, in which a thermodynamic cycle for heating the first container (11) is implemented, and a cooling configuration, in which a thermodynamic cycle for cooling the first container (11) is implemented, and vice versa.

12. Thermodynamic system (1) according to claim 11, characterized in that In the cooling configuration: - the at least one selective closing element (17) is closed to prevent the heat exchanger fluid from circulating in the hot gas branch (6); - the regulation device (7) for regulating the flow rate of the working fluid entering the first heat exchanger (4) is activated to allow the working fluid to flow in the first heat exchanger (4); - the thermostatic valve (10) is activated to allow the heat exchanger fluid to flow towards the second heat exchanger (5); - the bypass valve (13) is activated to allow the heat exchanger fluid to flow towards the first inlet (II) of the compressor (2).

13. Thermodynamic system (1) according to claim 11, characterized in that In the heating configuration: - the at least one selective closing element (17) is open to allow the heat exchanger fluid to circulate in the hot gas branch (6); - the thermostatic valve (10) is activated to allow the heat exchanger fluid to flow towards the second heat exchanger (5); - the bypass valve (13) is activated to allow the heat exchanger fluid to flow towards the first inlet (II) of the compressor (2). - said regulating device (7) for regulating the flow rate of the working fluid entering said inlet (4c) of said first heat exchanger (4) is inactive to prevent the working fluid from flowing in said first heat exchanger (4); - said bypass valve (13) is inactive so that the heat exchanger fluid flows through said bypass branch (12) towards said first inlet (II) of said compressor (2).

14. A machine (30) for manufacturing a liquid or semi-liquid food product, characterized in that, The combination comprising: - a processing unit (21) for manufacturing products of the liquid or semi-liquid food type, said processing unit comprising at least one first container (11) and a stirrer (23) mounted inside said at least one first container (11) to rotate inside said first container (11); - the thermodynamic system (1) according to any one of the preceding claims, operatively associated with said processing unit (21), said second heat exchanger (5) being associated with said at least one first container (11) to exchange heat with the products contained in said at least one first container (11).

15. The machine (30) according to claim 14, characterized in that, Said machine is a machine for making ice cream and said processing unit (21) is a batch freezing unit.

16. The machine (30) according to claim 14 or 15, characterized in that, Said machine is a pasteurizer and said processing unit (21) is a heating and / or cooling unit. Said machine is a pasteurizer and said processing unit (21) is a heating and / or cooling unit.

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