Thermodynamic system and machine comprising that system

Abstract

To solve a main drawback resulting from the use of CO2 in a system, namely, the low critical temperature and the high operating pressures thereof.SOLUTION: A thermodynamic system 1 for cooling or heating a first container 11 containing food products of the liquid or semi-liquid type comprises a circuit employing a transcritical heat exchanger fluid. The thermodynamic system 1 has: a compressor 2 with a first inlet I1 and a first outlet U1 for the heat exchanger fluid and a second inlet I2 and a second outlet U2 for the heat exchanger fluid; a first heat exchanger 4 including an inlet 4a and an outlet 4b for the heat exchanger fluid, the inlet being connected to the second outlet U2 of the compressor 2, the first heat exchanger including an inlet 4c and an outlet 4d for a service fluid; a second heat exchanger 5 associated with the first container 11; an inlet branch 35 for the heat exchanger fluid, extending from the outlet 4b 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 the outlet 5b of the second heat exchanger 5 to the first inlet I1 of the compressor 2; and a control and drive unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of machines for preparing liquid or semi-liquid foods.

[0002] In particular, the invention relates to a machine for liquid or semi-liquid food products, equipped with a thermodynamic system and the system of the invention. [Background technology]

[0003] In the industry of machines for liquid and semi-liquid products, for example in the ice cream, pastry or similar industries, it is known to thermally treat (i.e., cool and / or heat) a base product in order to carry out a predetermined recipe to produce a finished liquid or semi-liquid product.

[0004] Several heating systems of thermodynamic type are known that make it possible to thermally treat (heat or cool) a product in a container in order to modify its food / organoleptic characteristics.

[0005] In fact, by its very nature, professional ice cream machines not only need to cool and batch freeze the ice cream mixture, but also pasteurize it to ensure optimum hygiene.

[0006] The operating cycle of an ice cream machine therefore includes various steps: a step for cooling and producing the ice cream, and a pasteurization step which involves heating, maintaining and cooling the ice cream.

[0007] Furthermore, if the ice cream is to be cooled again after pasteurization, it needs to be batch frozen.

[0008] Batch freezing of ice cream is traditionally performed by combining a vapor compression refrigeration cycle with mechanical agitation.

[0009] Instead, the pasteurization process is carried out by injecting hot gas into an evaporator or by heat pump action of a vapor compression cycle.

[0010] It is also known that most thermodynamic cooling systems make it possible to cool a container by means of a thermodynamic circuit operating with a heat exchange fluid, and all comprise a pair of exchangers (evaporator and condenser) that use the heat exchange fluid, a compressor and a throttling element.

[0011] Typically, such systems use a hermetic or semi-hermetic compressor consisting of a casing enclosing a compression element acting on the refrigerating fluid and an electric motor therein.

[0012] Ice cream machines operate on a refrigeration cycle using a heat exchange fluid as a refrigerant.

[0013] To date, F gases have been used as refrigerants, among which, for example, HFOs (hydrofluoroolefins), which are fluorinated hydrocarbons forming the fourth generation of fluorinated refrigerant gases, are widely used.

[0014] An ideal coolant should have certain characteristics, including ensuring high energy efficiency, allowing for reduced system installation and maintenance costs, ensuring as little impact as possible on the environment, being non-toxic, and non-flammable.

[0015] The choice of technology and refrigerant should therefore be carefully considered depending on the market sector, the type of application, the various legal situations, the long-term installation and operating costs and, above all, future evolutions in terms of product availability. It is therefore worth considering that some gases currently available at low cost may become subject to significant price increases and / or quotas as a result of the mechanisms imposed by the F-Gas Regulation.

[0016] As can be easily imagined, energy efficiency issues not only affect the operating costs of a system, but also have a significant impact on environmental sustainability, which is why there is a growing trend to switch from HFO refrigerants to natural refrigerants.

[0017] One refrigerant that is defined as a natural refrigerant is CO2, which is considered the best solution due to its reduced environmental impact, even though the high pressures involved make the required system design very expensive. Therefore, CO2 is only a viable option for new systems.

[0018] Indeed, such naturally occurring gases have particular characteristics that make them suitable for the design and construction of refrigeration systems.

[0019] Because these gases are abundant in nature and are waste products of several industrial processes, they are very low cost and have a reduced environmental impact compared to the most widespread refrigerants: in fact, they have an ozone depletion potential (ODP) of zero and a global warming contribution (GWP) of one.

[0020] Finally, it is a non-toxic, non-flammable gas with optimal thermodynamic and heat exchange properties.

[0021] The main drawbacks arising from the use of CO2 in the system are its low critical temperature and the high operating pressures that characterize its use.

[0022] In fact, the refrigeration cycle of machines using conventional 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 special conception of the system. Summary of the Invention

[0023] In this context, the technical problem underlying the present invention is to propose a thermodynamic CO2 system that overcomes the above-mentioned drawbacks.

[0024] In particular, the object of the present invention is to provide a thermodynamic system that is capable of allowing the thermal treatment of liquid or semi-liquid food products and that is able to ensure operation under optimal conditions.

[0025] It is therefore a further object of the present invention to provide a thermodynamic system that allows for increased efficiency in the heating cycle.

[0026] It is a further object of the present invention to provide a thermodynamic system that allows for maintaining a sufficiently high pressure and temperature of the heat exchange fluid while efficiently managing the heating step.

[0027] The invention also relates to a machine for producing liquid or semi-liquid food products.

[0028] The technical problem and the specified object are substantially achieved by a thermodynamic system and machine comprising the technical features set forth in one or more of the appended claims. [Brief explanation of the drawings]

[0029] Further features and advantages of the present invention will become more apparent from the following illustrative, and therefore non-limiting, description of some preferred, but non-exclusive, embodiments of a thermodynamic system, as illustrated in the accompanying drawings. [Figure 1] 1 shows a diagram of a first possible embodiment of a thermodynamic system according to the invention; [Figure 2] 1 shows a diagram of a second possible embodiment of a thermodynamic system according to the invention; [Figure 3] FIG. 1 shows a schematic diagram of a machine for liquid or semi-liquid products with the thermodynamic system shown in the previous figure. [Figure 4] Quantitative trends in temperature values ​​reached by the mixture during the pasteurization step are shown. [Figure 5] Quantitative trends in pressure values ​​reached at various locations in the system during the pasteurization step are shown. DETAILED DESCRIPTION OF THE INVENTION

[0030] The thermodynamic system according to the present invention is designated by the numeral 1 in FIGS. 1-2 and will be referred to below as System 1 for ease of explanation.

[0031] Such a system 1 is applicable to machines 30 for the thermal treatment of liquid or semi-liquid hot or cold foods, such as ice cream, soft serve ice cream, yogurt, chocolate, sorbet, soups and other similar products.

[0032] In particular, the invention relates to a system 1 for cooling or heating at least one first container 11 containing a food product of the liquid or semi-liquid type.

[0033] According to the invention, a system 1 for cooling or heating at least one first container 11 containing a liquid or semi-liquid type food product comprises a circuit using a heat exchange fluid, preferably a transcritical type heat exchange fluid.

[0034] System 1, at a minimum, a compressor 2 with a first inlet "I1" and a first outlet "U1" for a heat exchange fluid and a second inlet "I2" and a second outlet "U2" for a heat exchange fluid; a first heat exchanger 4 with an inlet 4a for a heat exchange fluid and an outlet 4b for a heat exchange fluid;

[0035] 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 exchange fluid leaving the second outlet "U2" of the compressor 2 and a service fluid, preferably water (or alternatively air, or in either case any heat exchange service fluid).

[0036] The first heat exchanger 4 further comprises an inlet 4c for a service fluid, an outlet 4d for the service fluid, a second heat exchanger 5 associated with at least one first vessel 11; an inlet branch 35 for the heat exchange fluid, which extends from the outlet 4b for the heat exchange fluid of the first heat exchanger 4 to the inlet 5a of the second heat exchanger 5; an outlet branch 36 for the heat exchange fluid, which extends from the outlet 5b of the second heat exchanger 5 to the first inlet "I1" of the compressor 2; a control and drive unit 8.

[0037] It should be noted that the first container 11 can be of any type, such as a cylinder, a tank, etc.

[0038] According to one aspect of the present invention, the system 1 also includes: a first pressure transducer 28 configured to generate a pressure signal representative of the pressure of a heat exchange fluid flowing between the second outlet "U2" of the compressor 2 and the inlet 4a of the first heat exchanger 4; - regulating means 7 for regulating the flow rate of the service fluid flowing from the inlet 4c to the first heat exchanger 4. Furthermore, the regulating means 7 is operatively activatable via the control and drive unit 8 in response to pressure data obtained from the first pressure transducer 28.

[0039] The pressure switch 24 functions as a safety element that interrupts operation of the compressor 2 if the pressure (e.g., as detected by the pressure transducer 28) exceeds a predetermined deactivation value (e.g., a value between 120 and 140 bar, more preferably a value between 125 and 135 bar).

[0040] The control unit 8 is configured to activate the compressor 2 when the pressure (e.g., as detected by the pressure transducer 28) falls below a predetermined activation value (e.g., a value between 90 and 110 bar, more preferably a value between 95 and 105).

[0041] According to a further aspect of the present invention, the system 1 includes a bypass branch 12 and a bypass valve 13 .

[0042] The bypass branch 12 is arranged in parallel with a bypass valve 13 arranged along the outlet branch 36 downstream of the second heat exchanger 5 so that when the bypass valve 13 is inactive, the heat exchange fluid enters the bypass branch 12.

[0043] The bypass branch 12 has a second element 14 for reducing the pressure, configured to convey the heat exchange fluid at the outlet 5b of the second heat exchanger 5 directly towards the first inlet I1 of the compressor 2, where its pressure has been reduced.

[0044] The regulating means 7 for regulating the flow rate of the service fluid entering the heat exchanger 4 comprises a (preferably electronic, or alternatively mechanical) valve.

[0045] It should be noted that such a valve is a proportional valve (i.e. a valve that has several adjustment positions and thus allows for different apertures to be obtained).

[0046] Furthermore, the regulating means 7, which when active regulates the flow rate of the service fluid entering the first heat exchanger 4, allows the service fluid to enter the first heat exchanger 4 itself through the inlet 4C.

[0047] In other words, the first heat exchanger 4 is supplied with a service fluid which flows through the regulating means 7, which serves to proportionally adjust the flow rate of the service fluid in order to maintain a constant pressure in the cooling step by PID control via the readings of the first pressure transducer 28.

[0048] It should therefore be noted that the first pressure transducer 28 is configured to generate pressure data representing the pressure drop between two points in the system, specifically between the second outlet "U2" of the compressor 2 and the inlet 4a for the heat exchange fluid of the first heat exchanger 4.

[0049] Furthermore, the system 1 also comprises a thermostatic valve 10 arranged along the inlet branch 35 downstream of the first heat exchanger 4 relative to the flow direction of the heat exchange fluid in the inlet branch 35 .

[0050] The thermostatic valve 10 may be electronic, or alternatively may be mechanical.

[0051] The thermostatic valve 10 is operatively activatable by the control and drive unit 8 to adjust the load loss of the heat exchange fluid to control the evaporation pressure in the second heat exchanger 5 which, in use, defines the evaporator.

[0052] In other words, when activated, the thermostatic valve 10 allows the heat exchange fluid to flow towards the second heat exchanger 5 and through its inlet 5a.

[0053] It should also be noted that for the purposes of this specification, the terms activating or deactivating a valve means that the control and drive unit 8 is considered to act on the valve to facilitate opening or closing of the valve.

[0054] According to one embodiment, the system 1 also comprises first monitoring means 15 c for monitoring the temperature of the heat exchange fluid flowing in the inlet branch 35 .

[0055] The first monitoring means 15c is arranged upstream of the inlet 5a of the second heat exchanger 5 relative to the flow direction of the heat exchange fluid in the inlet branch 35.

[0056] The first monitoring means 15 c is configured to provide temperature data of the heat exchange fluid in the inlet branch 35 , in particular at a location between the thermostatic valve 10 and the inlet 5 a of the second heat exchanger 5 .

[0057] According to one embodiment, the system 1 also comprises second monitoring means 15d for monitoring the temperature of the heat exchange fluid flowing in the outlet branch .

[0058] The second monitoring means 15d is arranged downstream of the outlet 5b of the second heat exchanger 5 relative to the flow direction of the heat exchange fluid in the outlet branch 36, and the second monitoring means 15d is configured to provide temperature data of the heat exchange fluid downstream of the second heat exchanger 5.

[0059] According to another embodiment, the system 1 also comprises a second pressure transducer 29 arranged along the outlet branch 36 downstream of the second monitoring means 15d and configured to provide pressure data of the heat exchange fluid downstream of the second heat exchanger 5.

[0060] The adjustment of the thermostatic valve 10 is carried out in response to the temperature data of the first monitoring means 15c and the second monitoring means 15d and the pressure data of the second pressure transducer 29, thereby evaluating the temperature gradient and the corresponding pressure upstream and downstream of the heat exchanger 5.

[0061] Furthermore, according to one embodiment, the system 1 further comprises: - a temperature sensor 15e configured to provide the control and drive unit 8 with temperature data representative of the temperature of the heat exchange fluid entering the first inlet "I1" of the compressor 2; a temperature sensor 15a configured to provide the same control and drive unit 8 with temperature data representative of the temperature of the heat exchange fluid entering the second inlet "I2" of the compressor 2.

[0062] According to another aspect of the present invention, the system 1 further comprises a third heat exchanger 3 connected to the first outlet “U1” and the second inlet “I2” of the compressor 2.

[0063] The third heat exchanger 3 is configured to allow heat exchange between the heat exchange fluid and a service fluid, preferably water.

[0064] The heat exchanger 3 comprises an inlet 3c for a service fluid and an outlet 3d for a service fluid.

[0065] It should be noted that there is an electrovalve 16 that can be activated by the control and drive unit 8, which is regulated by the data output from the temperature sensor 15a, to regulate the flow rate of the service fluid entering the third heat exchanger 3 via the inlet 3c.

[0066] According to another embodiment, the system comprises a bypass valve 13 that is operatively activatable by the control and drive unit 8 to allow the heat exchange fluid to flow towards the first inlet "l1" of the compressor 2.

[0067] The bypass valve 13 is arranged along the outlet branch 36 downstream of the second heat exchanger 5 relative to the flow direction of the heat exchange fluid in the outlet branch 36 .

[0068] The bypass valve 13 is arranged in parallel with the bypass branch 12, and when the bypass valve 13 is inactive, the heat exchange fluid flows into the bypass branch 12, which includes a second pressure reduction element 14 operatively associated with the bypass branch 12.

[0069] The second pressure reduction element 14 serves to reduce the pressure of the heat exchange fluid entering the first inlet "I1" of the compressor 2 while maintaining a 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 a high pressure value.

[0070] Preferably, the bypass valve 13 is controlled to either completely close or completely open the bypass branch 12, prohibiting or allowing the circulation of the heat exchange fluid inside the bypass branch 12 and thus the resulting flow within the second pressure reduction element 14.

[0071] In other words, to reduce the pressure of the heat exchange fluid entering the first inlet "I1" of the compressor 2, the bypass valve 13 is closed and sends the entire flow to the second pressure reduction element 14, which therefore causes a pressure and temperature jump.

[0072] It should be noted that the cooling of the heat exchange fluid occurs due to the pressure jump created by the second pressure reduction element 14 .

[0073] Additionally, the temperature of the heat exchange fluid entering the inlet "I1" of the compressor 2 is constantly monitored by a temperature sensor 15e to maintain sufficient superheat to avoid falling into the saturated vapor curve.

[0074] To obtain the required superheat, the bypass valve 13 is activated intermittently to correct the pressure jump when the superheat needs to be increased.

[0075] In other words, the temperature of the heat exchange fluid entering the first inlet "l1" of the compressor 2 is reduced by flowing through the second temperature reducing element 14 and is constantly monitored by the temperature sensor 15e.

[0076] It is therefore clear that thanks to the innovation of the bypass branch 12, the temperatures of the components of the compressor 2 always remain low, even when the hot gas cycle is used.

[0077] Advantageously, when the bypass valve 13 is inactive, the bypass branch 12 is configured to draw the heat exchange fluid from the second heat exchanger 5 to the outlet branch 36 and, after performing a corresponding pressure / temperature reduction thereon, convey it to the first inlet "l1" of the compressor 2.

[0078] Because the heat exchange fluid is relatively cold, at the inlet of the compressor 2 it draws thermal energy from the hottest parts of the compressor 2, causing the temperature of the compressor 2 to decrease, i.e. causing it to cool down, thus reducing the thermal stress to which the compressor 2 is subjected.

[0079] According to a further aspect of the invention, the system 1 comprises a hot gas branch 6 for implementing a hot gas thermodynamic cycle.

[0080] The hot gas branch 6 is configured to convey the heat exchange fluid from the second outlet “U2” of the compressor 2 towards the inlet 5 a of the second heat exchanger 5 .

[0081] According to the diagram of the system 1 shown in FIG. 1, the hot gas branch 6 has at least one selective closure element 17 and a first pressure reduction element 20 .

[0082] The selective closure element 17 is operatively associated with the hot gas branch 6 and is configured to close and open such hot gas branch 6 to prohibit or allow circulation of heat exchange fluid therein.

[0083] A first pressure reduction element 20 always operatively associated with the hot gas branch 6 is located upstream of the selective closure element 17 relative to the flow direction of the heat exchange fluid in the inlet branch 35 .

[0084] Further aspects and details of system 1 are described next.

[0085] 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 portion between the heat exchange fluid flowing along the inlet branch 35 and the heat exchange fluid flowing along the outlet branch 36.

[0086] According to a preferred embodiment, the system 1 further comprises a dewatering filter 18 which makes it possible to ensure the cleaning of the heat exchange fluid and which facilitates the removal of impurities accumulated by the fluid during the cooling or heating cycle, in particular when passing through the compressor 2.

[0087] As shown in detail in the accompanying FIG. 1, the dewatering filter 18 is arranged along an inlet branch 35 interposed between the outlet 4b for the heat exchange fluid of the first heat exchanger 4 and the inlet 5a of the second heat exchanger 5.

[0088] In practice, the system 1 of FIG. 1 can be switched between a heating configuration in which a thermodynamic heating cycle of the first vessel 11 is performed, and a cooling configuration in which a thermodynamic cooling cycle of the first vessel 11 is performed.

[0089] Therefore, although an implementation for reducing the temperature of the heat exchange fluid in FIG. 1 will now be described, it can also be implemented separately in the system 1.

[0090] In the first stage of the cooling configuration, the heat exchange fluid is cooled using a service fluid, preferably water, which enters the compressor 2 through a heat exchanger 3 which serves to cool the service fluid before it is processed in the second compression stage.

[0091] The flow rate of the service fluid entering the inlet 3c of the heat exchanger 3 is regulated by an electrovalve 16 depending on the temperature of the service fluid flowing through the outlet 3b of the compressor 3 and sensed by a temperature sensor 15a.

[0092] Preferably, the flow rate at the inlet 3c of the heat exchanger 3 is intermittently regulated by an electrovalve 16, which is activated simply when a predetermined temperature (e.g., 35°C) detected by the temperature sensor 15a is reached.

[0093] According to another embodiment, the electrovalve 16 is deactivated when the temperature detected by the temperature sensor 15a falls below a predetermined hysteresis value (eg, 0.5° C.) relative to the above-mentioned predetermined temperature.

[0094] After this first step, the heat exchange fluid is processed by a second compression stage.

[0095] The heat exchange fluid is conveyed through a second outlet "U2" of the compressor 2 to the heat exchanger 4 and flows through its inlet 4a.

[0096] The heat exchanger 4 further cools the heat exchange fluid by a service fluid, preferably water, which enters the heat exchanger 4 through an inlet 4c.

[0097] The flow rate of the service fluid entering the inlet 4c of the heat exchanger is regulated by regulating means 7 comprising an electronically controlled valve.

[0098] In this step, the regulating means 7 regulating the flow rate of the service fluid entering the heat exchanger 4 is active, allowing the service fluid to flow through the heat exchanger 4 itself.

[0099] In other words, the flow rate of the service fluid is regulated by the regulating means 7 in response to pressure data generated by the first pressure transducer 28, which represents the pressure of the heat exchange fluid flowing between the second outlet "U2" of the compressor 2 and the inlet 4a for the heat exchange fluid in the heat exchanger 4.

[0100] Since the selective closing element 17 is closed to prohibit the circulation of the heat exchange fluid inside the hot gas branch 6, the heat exchange fluid flowing through the outlet "U2" of the compressor 2, and therefore exiting the second stage of the compressor 2, is conveyed completely to the heat exchanger 4.

[0101] The heat exchange fluid flowing through the outlet 4b of the heat exchanger 4 travels along the inlet branch 35 and passes through the dehydration filter 18 and the regenerative heat exchanger 9, which serves to further cool the heat exchange fluid.

[0102] The same heat exchange fluid then reaches the thermostatic valve 10, which is active and allows the heat exchange fluid to flow towards the inlet 5a of the heat exchanger 5.

[0103] The thermostatic valve 10 is adjusted by increasing or decreasing the load loss to maintain a particular evaporating pressure in response to the temperatures at the inlet 5a and outlet 5b of the heat exchanger 5 monitored by the first and second temperature monitoring means 15c, 15d, and in response to the pressure monitored by the second pressure transducer 29.

[0104] The heat exchange fluid flowing from the outlet branch 36, and therefore from the evaporator outlet 5b, passes again through the regenerative heat exchanger 9 and through the bypass valve 13, which is active and allows the heat exchange fluid to flow towards the first inlet "I1" of the compressor 2.

[0105] In other words, after passing through the bypass valve 13, the heat exchange fluid reaches the inlet "I1" of the first stage of the compressor 2, and in front of the inlet "I1" there is a temperature sensor 15e, which is configured to provide the control and drive unit 8 with temperature data of the heat exchange fluid entering the first inlet "I1" of the compressor 2.

[0106] In contrast, the embodiment for increasing the temperature of the heat exchange fluid shown in FIG. 1 can also be implemented separately in the system 1 and is described below.

[0107] The system 1 in fact makes it possible to increase the temperature and pressure of a heat exchange fluid, as will be explained below.

[0108] In the initial heating step, it is necessary to heat the heat exchanger 4 to ensure that the service fluid stored in this heat exchanger 4 is not kept cold and inert, but is kept at a high enough temperature to allow the pressure in the system 1 to be increased.

[0109] For this purpose, it is necessary to perform a short switching step in which the thermostatic valve 10 is fully opened to allow the heat exchange fluid to flow towards the heat exchanger 5, while the selective closing element 17 remains closed to prevent the heat exchange fluid from circulating in the hot gas branch 6.

[0110] At these moments, the regulating means 7 for regulating the flow rate of the service fluid is inactive, preventing the service fluid from flowing through the heat exchanger 4. It should also be noted that the temperature output from the heat exchanger 4 is monitored by the temperature monitoring means 15b.

[0111] The thermostatic valve 10 can then be fully closed while the selective closing element 17 is opened to convey the heat exchange fluid flowing from the second outlet “U2” of the compressor 2 into the heat exchanger 5.

[0112] Note that in the initial heating step, the heat exchange fluid reaches a transcritical stage before the next step begins.

[0113] In other words, during the heating step, at least one selective closing element 17 installed in the hot gas branch 6 is open so as to allow the heat exchange fluid to circulate in the hot gas branch 6, and the regulating means 7 regulating the flow rate of the service fluid entering the inlet 4c of the first heat exchanger 4 is inactive so as to prohibit the service fluid from flowing in the heat exchanger 4.

[0114] Indeed, the flow of fresh service fluid through the regulating means 7 and therefore through the heat exchanger 4 will result in a decrease in the temperature of the heat exchange fluid.

[0115] The hot gas branch 6 must be regulated so that the pressure is reduced by the pressure reducing element 20 to allow the desired increase in temperature of the second stage compression circuit (i.e. the circuit originating from the second outlet "U2" of the compressor 2).

[0116] The bypass valve 13 is closed to lower the temperature of the heat exchange fluid flowing through the inlet "I1" of the compressor 2 and thus entering the first stage of the compressor 2, and to further increase the resulting temperature and pressure at the second outlet "U2" of the compressor 2 and therefore exiting the second stage of the compressor 2.

[0117] Therefore, the entire flow of the outlet branch 36 is conveyed into the bypass branch 12, more specifically into the second pressure reducing element 14 of the bypass branch 12, which causes a pressure and temperature jump.

[0118] The resulting temperature of the heat exchange fluid at the first inlet "I1" of the compressor 2 is therefore reduced and is constantly monitored by the temperature sensor 15e.

[0119] In other words, the bypass valve 13 is inactive so that the heat exchange fluid flows through the bypass branch 12 towards the first inlet “I1” of the compressor 2 .

[0120] The bypass branch 12 is provided with a pressure reducing element 14 .

[0121] As previously mentioned, CO2 systems are characterized by high operating pressures, so before the heat exchange fluid re-enters the first inlet "I1" of the compressor 2, its pressure and temperature must be reduced.

[0122] Thus, branch 12 and element 14 are used to manage the heating step with high efficiency while limiting the pressure value at the first inlet "i1" of compressor 2.

[0123] In fact, when analyzing the graph of Figure 5, which depicts the trends in pressure values ​​during pasteurization, i.e., the heating step, at different points in the system 1, it is clear that the pressure value of the heat exchange fluid adjacent to the first inlet "I1" of the compressor 2 is lower than the pressure value of the heat exchange fluid adjacent to the second outlet "U2" of the compressor 2.

[0124] Furthermore, the graph in the attached Figure 4 depicts the temperature trend of the ice cream mix contained in the first container 11 during the pasteurization step, i.e. during a step at a temperature close to 100°C to ensure optimal hygiene.

[0125] According to the present invention there is also provided a machine 30 for producing liquid or semi-liquid food products, the machine 30 comprising: a processing unit 21 for producing liquid or semi-liquid food products, comprising at least one container 11 and an agitator 23 arranged inside the at least one first container 11 and rotating inside the first container 11; - a system 1 operatively associated with a processing unit 21; in combination with a second heat exchanger 5 associated with the at least one first container 11 for exchanging heat with the product contained in the at least one first container 11;

[0126] According to another embodiment, the machine is an ice cream machine and the processing unit 21 is a batch freezing unit, and further the machine 30 is a pasteurizer and the processing unit 21 is a heating and / or cooling unit.

[0127] It should be noted that, according to the present invention, the thermodynamic system can be applied to any type of machine capable of thermally treating liquid or semi-liquid products.

[0128] Advantageously, the system 1 according to the invention makes it possible to overcome the above-mentioned deficiencies of the prior art.

[0129] Advantageously, a system 1 is provided that is able to allow the thermal treatment of liquid or semi-liquid food products and ensures operation under optimal conditions.

[0130] Advantageously, a system 1 is provided that is capable of improving the efficiency of the heating cycle.

[0131] Advantageously, a system 1 is provided that allows for maintaining a sufficiently high pressure and temperature of the heat exchange fluid while managing the heating step with high efficiency.

Claims

1. A thermodynamic system (1) for cooling or heating at least one first container (11) containing a liquid or semi-liquid type food product, comprising a circuit using a heat exchange fluid, preferably a transcritical heat exchange fluid, said thermodynamic system comprising at least: a compressor (2) with a first inlet (I1) and a first outlet (U1) for said heat exchange fluid and a second inlet (I2) and a second outlet (U2) for said heat exchange fluid; a first heat exchanger (4) connected to the second outlet (U2) of the compressor (2), comprising an inlet (4a) for the heat exchange fluid and an outlet (4b) for the heat exchange fluid, the first heat exchanger (4) being configured to allow heat exchange between the heat exchange fluid and a service fluid, the first heat exchanger (4) comprising an inlet (4c) for the service fluid and an outlet (4d) for the service fluid; a second heat exchanger (5) associated with said at least one first vessel (11); an inlet branch (35) for the heat exchange fluid, extending from the outlet (4b) for the heat exchange fluid of the first heat exchanger (4) to the inlet (5a) of the second heat exchanger (5); an outlet branch (36) for said heat exchange fluid, extending from the outlet (5b) of said second heat exchanger (5) to said first inlet (I1) of said compressor (2); - a control and drive unit (8), The thermodynamic system (1) comprises: a first pressure transducer (28) configured to generate a pressure data signal representative of the pressure of the heat exchange fluid flowing between the second outlet (U2) of the compressor (2) and the inlet (4a) for the heat exchange fluid of the first heat exchanger (4); - adjusting means (7) for adjusting the flow rate of said service fluid entering said inlet (4c) of said first heat exchanger (4), said adjusting means (7) being operatively activatable via said control and drive unit (8) in response to said pressure data signal.

2. 2. The thermodynamic system (1) according to claim 1, wherein the service fluid entering the inlet (4c) of the first heat exchanger (4) is water, and the regulating means (7) for regulating the flow rate of the service fluid entering the first heat exchanger (4) comprises an electronic control valve.

3. a thermostatic valve (10) installed downstream of the first heat exchanger (4) along the inlet branch (35) relative to the flow direction of the heat exchange fluid in the inlet branch (35), the thermostatic valve (10) being operatively activatable via the control and drive unit (8) to adjust the load loss of the heat exchange fluid in order to adjust a predetermined evaporation pressure in the second heat exchanger (5); a bypass valve (13) arranged downstream of the second heat exchanger (5) along the outlet branch (36) relative to the flow direction of the heat exchange fluid in the outlet branch (36), the bypass valve (13) being operatively activatable via the control and drive unit (8) to allow the heat exchange fluid to flow towards the first inlet (I1) of the compressor (2).

4. - first monitoring means (15c) for monitoring the temperature of the heat exchange fluid flowing in the inlet branch (35), the first monitoring means (15c) being located upstream of the inlet (5a) of the second heat exchanger (5) relative to the flow direction of the heat exchange fluid in the inlet branch (35) and configured to provide a temperature data signal of the heat exchange fluid; - second monitoring means (15d) for monitoring the temperature of the heat exchange fluid flowing in the outlet branch (36), the second monitoring means (15d) being located downstream of the outlet (5b) of the second heat exchanger (5) relative to the flow direction of the heat exchange fluid in the outlet branch (36) and configured to provide a temperature data signal of the heat exchange fluid; a second pressure transducer (29) located along said outlet branch (36) downstream of said second monitoring means (15d) and configured to provide a pressure data signal of the heat exchange fluid; 4. The thermodynamic system (1) according to claim 1, wherein the thermostatic valve (10) is adjusted in response to the temperature data signals from the first monitoring means (15c) and the second monitoring means (15d) and the pressure data signal from the second pressure transducer (29).

5. 5. The thermodynamic system (1) according to claim 1, further comprising a temperature sensor (15e) configured to provide the control and drive unit (8) with a temperature data signal representative of the temperature of the heat exchange fluid entering the first inlet (I1) of the compressor (2).

6. a temperature sensor (15a) configured to provide said control and drive unit (8) with a temperature data signal representative of the temperature of said heat exchange fluid entering said second inlet (12) of said 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), configured to allow heat exchange between the heat exchange fluid and a service fluid, the third heat exchanger (3) comprising an inlet (3c) for the service fluid and an outlet (3d) for the service fluid; - an electrovalve (16) connected to the inlet (3c) for the service fluid entering the heat exchanger (3) and activatable via the control and drive unit (8) to regulate the flow rate of the service fluid entering the third heat exchanger (3).

7. 7. The thermodynamic system (1) according to any one of claims 1 to 6, comprising a dewatering filter (18) installed along the inlet branch (35) between the outlet (4b) of the heat exchange fluid of the first heat exchanger (4) and the inlet (5a) of the second heat exchanger (5).

8. a hot gas branch (6) for implementing a hot gas thermodynamic cycle, the hot gas branch (6) being configured to convey the heat exchange fluid leaving the second outlet (U2) of the compressor (2) to the inlet (5a) of the second heat exchanger (5); at least one selective closure element (17) operatively associated with said hot gas branch (6) and configured to close and open said branch (6) so as to prevent or allow the flow of heat exchange fluid therein; - a bypass branch (12) configured to convey the heat exchange fluid leaving the outlet (5b) of the second heat exchanger (5) directly to the first inlet (I1) of the compressor (2).

9. a first pressure reduction element (20) operatively associated with said hot gas branch (6) upstream of said selective closure element (17) relative to the flow direction of said heat exchange fluid; - a regenerative heat exchanger (9) configured to define a heat exchange section between the heat exchange fluid flowing along the inlet branch (35) and the heat exchange fluid flowing along the outlet branch (36).

10. 9. The thermodynamic system of claim 8 when dependent on claim 3, wherein the bypass branch is disposed parallel to the bypass valve such that the heat exchange fluid flows into the bypass branch when the bypass valve is inactive, and the bypass branch has a second pressure reduction element operatively associated with the bypass branch.

11. 11. A thermodynamic system (1) according to any one of claims 1 to 10, wherein the system (1) is switchable in use between a heating configuration in which a thermodynamic cycle for heating the first vessel (11) is performed and a cooling configuration in which a thermodynamic cycle for cooling the first vessel (11) is performed.

12. In the cooling configuration, - said at least one selective closure element (17) is closed so as to prevent said heat exchange fluid from circulating in said hot gas branch (6); - the regulating means (7) for regulating the flow rate of the service fluid entering the first heat exchanger (4) are active so as to allow the service fluid to flow through the first heat exchanger (4); - the thermostatic valve (10) is active to allow the heat exchange fluid to flow towards the second heat exchanger (5); A thermodynamic system (1) according to claim 11, wherein the bypass valve (13) is active to allow the heat exchange fluid to flow towards the first inlet (I1) of the compressor (2).

13. In the heating configuration, - said at least one selective closure element (17) is open to allow said heat exchange fluid to circulate in said hot gas branch (6); - the regulating means (7) for regulating the flow rate of the service fluid entering the inlet (4c) of the first heat exchanger (4) are inactive so as to prevent the service fluid from flowing through the first heat exchanger (4); The thermodynamic system (1) according to claim 11, wherein the bypass valve (13) is inactive so that the heat exchange fluid flows through the bypass branch (12) towards the first inlet (I1) of the compressor (2).

14. A machine (30) for producing liquid or semi-liquid food products, comprising: a processing unit (21) for producing a liquid or semi-liquid food-type product, said processing unit (21) comprising at least one first container (11) and an agitator (23) mounted inside said at least one first container (11) and rotating inside said first container (11); - a machine (30) comprising in combination a thermodynamic system (1) according to any one of claims 1 to 13, said thermodynamic system (1) being operatively associated with said processing unit (21), said second heat exchanger (5) being associated with said at least one first container (11) and exchanging heat with a product contained in said at least one first container (11).

15. 15. Machine (30) according to claim 14, wherein said machine is a machine for producing ice cream and said processing unit (21) is a batch freezing unit.

16. 16. Machine (30) according to claim 14 or 15, wherein the machine is a pasteurizer and the processing unit (21) is a heating and / or cooling unit.

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