FIELD OF TECHNIQUE

The present invention relates to an improved refrigeration plant. Preferably, the refrigeration plant is powered by renewable energy. More in detail, the present invention relates to a plant equipped with at least one refrigerating chamber which defines inside it an environment with controlled temperature and/or humidity which allows the conservation, refrigeration and/or pre-refrigeration of different types of products, such as such as food or medicines, etc.

This plant therefore finds advantageous use in the technical sector of the production and marketing of thermo-technical plants and in particular in the sector of the production of plants comprising cold rooms, preferably powered by sources of electricity of the renewable type.

STATE OF THE ART

In the reference technical sector mentioned above, refrigeration systems have been known for some time, which exploit a per se well-known thermodynamic refrigeration cycle to cool the internal environment of a refrigeration chamber.

The cold rooms of refrigeration systems are normally rooms made with insulating panels made of expanded material with high thermal insulation, usually housed inside industrial warehouses.

The chambers are equipped with suitable doors which place the internal refrigerated environment of the chamber with the external environment, which are used to access the inside of the chamber and place and/or remove the products to be kept at the right temperature.

Known types of refrigeration systems are equipped with cold production units, which generally include groups of compressors (known in the technical jargon of the sector with the term "motor-condensing units") which are normally arranged outside the shed where they are operated to compress a fluid capable of absorbing heat from the chamber and then disposing of it into the external environment through a heat exchange coil, in a known manner. This fluid is then pushed at high pressure through an orifice/nozzle where it evaporates due to the sudden drop in pressure, cooling down. This cooled fluid then enters the evaporator, (or heat exchange coil) where it absorbs heat from a flow of air blown through the evaporator by means of a fan. At that point the fluid is sucked in by the compressor, and the cycle repeats itself, keeping the internal environment of the refrigeration chamber cooled.

The refrigeration chambers of systems of the known type require a constant high- power electrical supply in order to be able to maintain the desired temperature inside the refrigerating chamber. Obviously, this need for a continuous and/or constant supply of large energy translates into high management and maintenance costs.

The use of plants for the production of electric energy from renewable sources is also already known, such as in particular plants which provide for the use of photovoltaic panels. However, photovoltaic technology bears the intrinsic drawback of its functionality only during the day, resulting in fact useless during the night.

It is also known the widespread use of electric accumulators connected to photovoltaic panels to store sufficient electric energy to then feed the plant during the night hours. However, these electric accumulators are extremely expensive and have a short useful life.

Therefore, the use of accumulators for electric energy results in a strong economic and environmental drawback, requiring the periodic disposal of the electric accumulators and their treatment as waste.

With reference to figure A, it is possible to note the area P of the production of electrical energy from a photovoltaic source and the profile C of the electrical energy consumption of a normal refrigerating chamber of a known type of refrigeration system.

In this operating regime, the economic savings deriving from the use of such a system, with photovoltaic power supply but without electric energy storage, is usually between 15% and 25% of the total consumption of a system which is powered only by the electricity grid, electricity distribution, since refrigerating machines typically operate 24 hours a day, seven days a week with an electricity absorption profile that shows little difference in consumption between day and night.

From figure A it is also possible to observe the normal trend of electrical energy absorption by the refrigerating system, known as the load profile, during the twenty-four hours of the day. It is possible to note four B peaks which correspond to the activation of defrosts to defrost the evaporators.

In particular, as is known, when the evaporator of a refrigeration system and/or a cold room operates at a temperature equal to or lower than 0°C, in the presence of a high humidity rate inside the room, it progressively covered by a layer of frozen vapor, known as frost. In this situation, the greater the layer of frost, the lower the heat transfer coefficient of the evaporator, thus decreasing the efficiency of the entire system. Therefore, the need to overcome this drawback by periodically defrosting the evaporator is known and felt in the sector. Evaporator defrosting is normally carried out by heating the evaporator - in particular by powering electric heaters - with a quantity of heat sufficient to completely melt the frost in a limited period of time, normally 0.5 - 1 hour . This defrosting operation obviously requires additional electrical energy which can be seen in peaks B in figure A. Defrosting is, in some cases, performed by replacing the refrigerant fluid with a hot gas of the same mixture, taken from the condenser unit. However, this provision is more expensive (particularly in terms of implementation) than electric heating and is therefore little used.

A further drawback lies in the fact that the defrosting phase introduces heat into the refrigerating chamber which must then be removed, resulting in further work.

In a known manner, the system comprises an electronic control unit (or central unit), equipped with or connected to suitable temperature sensors, configured to operate the expansion valve which causes a drop in pressure of the refrigerant fluid and simultaneously activates the fan of the 'evaporator to cool the air inside the chamber and/or cold room. This drop in pressure is detected by a pressure switch on the compressor unit which is activated accordingly.

In more detail, the electronic control unit, when the internal temperature sensor detects a temperature value higher than a threshold value, i.e. suitable for starting the production of cold, is configured to operate the aforementioned expansion valve. I n this way, therefore, the pressure of the refrigerant gas drops and the compressor detects this drop by means of its pressure switch. This pressure switch then sends an activation signal to operate the compressor unit.

The defrost procedures are generally commanded at pre-established times by the control units which activate, for about 30-60 minutes, the electrical resistances located in the evaporator radiators, after having blocked them for the same amount of time. This obviously results in a waste of energy which usually occurs for about 30-60 minutes every 4-6 hours, regardless of whether or not defrosting is actually needed.

The production of electricity by a normal photovoltaic system follows a bell-shaped pattern according to the dotted line T of figure A in which it is easy to see how this energy is not fully exploited. In particular, during a normal power supply day of at least one refrigeration chamber (in which the load is defined by profile C) only area P in figure A is used, which means that the remaining energy which is in any case produced by the plant photovoltaic (as shown by the dotted line T) is fed into the grid or dissipated or again the photovoltaic inverter is configured to reduce the production of electric power, effectively invalidating the possible productivity.

It follows that a normal photovoltaic system combined with a refrigeration chamber can lead to a maximum energy saving of around 15%-25% compared to a refrigeration system not equipped with photovoltaic generation, precisely because this energy production is scarcely exploited. In this situation, the drawback of the high cost of electrical energy due to the high energy consumption by the refrigerating chambers is currently solved in an unsatisfactory way by the production plants using photovoltaic renewable energy.

A further drawback lies in the fact that the compressors of known refrigeration systems are subjected to many start/stop cycles which consume a lot of energy for the same amount of refrigeration produced and subject the compressors themselves to greater mechanical stress, thus requiring frequent maintenance to be carried out.

OBJECTS OF THE INVENTION

The object of the invention is to propose a refrigeration plant which allows to obviate, at least in part, the drawbacks of the known art mentioned above.

Another object of the invention is to provide a refrigeration plant which is perfectly reliable.

Another object of the invention is to propose a refrigeration plant which is powered by means for generating electric power from renewable sources, preferably by means of photovoltaic means.

Another object of the invention is to propose a refrigeration plant which allows to fully exploit means of electric power supply from renewable sources with high energy efficiency.

Another object of the invention is to propose a refrigeration system which is capable of maintaining a desired temperature inside the refrigerating chamber even in the event of a temporary power failure.

Another object of the invention is to propose a refrigeration plant which exploits means of electric power supply from renewable sources without requiring the use of electric accumulators.

Another object of the invention is to propose a refrigeration plant which is constructively simple and wholly reliable.

Another object of the invention is to propose a refrigeration plant which allows it to be used continuously throughout a working day.

Another object of the invention is to propose a refrigeration plant which can be easily manufactured and with contained costs.

Another object of the invention is to propose a refrigeration plant which is an alternative and/or an improvement on the known solutions.

SUMMARY OF THE INVENTION

All these objects, both individually and in any combination thereof, and others which will result from the following description are achieved, according to the invention, with a refrigeration plant according to claim 1 . In particular, the aforementioned objects are achieved by a refrigeration plant 1 for cooling and/or preserving products, which plant comprises:

- at least one refrigerating chamber 100, internally defining at least one internal volume configured to contain at least one product to be cooled and/or preserved;

- a refrigerating circuit 2, operatively connected to said refrigerating chamber and configured to cool the internal volume of said refrigerating chamber (100); said cooling circuit 2 comprising at least one compressor unit 6, at least one evaporator unit 4, at least one condenser unit 3 and at least one expansion unit 7,

- electric power supply means 8 for said refrigeration circuit 2;

- electronic control means 10 and/or 14 electrically connected at least to said expansion unit 7 and/or to said evaporator unit 4; and in which the electronic control means 10 and/or 14 are configured to control when fully operational (i.e. after the first activation/deactivation cycle and not at the time of installation), within a period of time equal to or greater than one hour (preferably at least 4- 5 hours), the opening of said expansion unit 7 and/or the activation of said evaporator unit

4 so that the compressor unit 6 of said cooling circuit 2 remains always and continuously activated within said period of time equal to or greater than one hour (preferably at least 4 -

5 hours), thus avoiding and/or reducing the activation/deactivation cycles of the compressor unit within said period of time .

Advantageously, the system comprises at least one temperature sensor 15 arranged inside said internal volume, electrically connected to said control means 10 or 14 and capable of detecting the actual internal temperature of said internal volume of said refrigerating chamber 100, for thus sending at least one signal to said control means 10 and/or 14 representative of said effective internal temperature Teff of said internal volume.

Conveniently, the control means 10 are configured to compare said signal representative of said effective internal temperature Teff with a reference temperature value Ts and to command, on the basis of said comparison, the activation or otherwise of said refrigeration circuit 2. In particular, if Teff is greater than Ts then the cooling circuit 2 is activated (in particular the opening of said expansion unit 7 and/or the activation of said evaporator unit 4 is commanded, thus causing activation of the compressor unit 6), while if Teff is lower than Ts then the refrigerant circuit 2 is not activated.

Conveniently, the reference temperature Ts is set:

- to a first value Td during a first period of time (preferably corresponding to the daytime hours of the day) and/or when the electric power supply means 8 are activated, - to a second value Tn, which is different from the first value Td, during a second and different period of time (preferably corresponding to the night hours of the day) and/or when the electric power supply means 8 are deactivated.

Conveniently, during the first period of time (preferably corresponding to the daytime hours of the day) and/or when the electric power supply means 8 are activated, the first value Td is set so that the comparison between the temperature Teff and Td causes the continuous and constant activation of said cooling circuit 2 so as to try to bring the temperature Teff to a value equal to or lower (or in any case as close as possible) to Td. In particular, during the first period of time (preferably corresponding to the daytime hours of the day) and/or when the electric power supply means 8 are activated, Teff is greater than Td and therefore the refrigeration circuit 2 is and remains activated.

Conveniently, during the second period of time (preferably corresponding to the night hours of the day) and/or when the electric power supply means 8 are not activated, Tn is set so that the comparison between the temperature Teff and Tn does not cause the activation of said refrigerant circuit 2, except when T eff is greater than Tn in order to promptly bring it back below Tn.

Advantageously, the first value Td is lower than the second value Tn.

Preferably, Td and Tn are set so that Teff fluctuates within the range between Td and Tn.

Preferably, said electric power supply means 8 are of the photovoltaic type.

Conveniently, said electric power supply means 8 are associated with said refrigeration circuit 2 so as to electrically supply corresponding components of said refrigeration circuit 2 at least during the hours - generally of the day - of photovoltaic production.

Advantageously, the control means 10 and/or 14 are configured to control, within the period of time in which the photovoltaic type electric power supply means 8 produce electric power (for example greater than a threshold), the opening of said expansion unit 7 and/or the activation of said evaporator unit 4 so that, when fully operational (i.e. after the first activation/deactivation cycle or cycles and therefore after the first installation) the compressor unit 6 of said refrigerant circuit 2 remains always and continuously activated within said period of time, thus avoiding and/or reducing the activation/deactivation cycles of the compressor unit within said period of time.

In other words, within said period of time in which the photovoltaic electric power supply means 8 produce electric power, the compressor unit 6 is always and continuously activated, this allows to avoid continuous activation/deactivation cycles of the compressor unit 6 which, in the long, damage the compressor unit 6 itself, as well as allowing for a reduction in consumption for the same amount of refrigeration produced by the refrigeration circuit 2.

Advantageously, the first Td value is lower than the second Tn value by at least 2°C, preferably at least 4°C and more preferably at least 6°C.

Advantageously, the first value Td is set in such a way that the absorption of electric energy by said refrigeration circuit 2 follows the electric energy production trend of said electric power supply means 8 of the photovoltaic type.

Advantageously, the system 1 comprises thermal accumulation means 20, arranged inside said refrigerating chamber 100, and configured for:

- accumulate coolness during a first period of time, preferably corresponding to the daylight hours of the day, and/or when the supply means 8 produce electric power, and

- to release frigories inside said refrigerating chamber 100 during a second period of time, preferably corresponding to the night hours of the day, and/or when the supply means 8 do not generate electric power.

Preferably, the heat storage means 20 are configured to lower the temperature inside the refrigerating chamber 100 during the day and to reduce the temperature increase inside said refrigerating chamber 100 during the night.

Advantageously, said heat storage means 20 are equipped with a thermal capacity sufficient to allow heat absorption during the night hours to thus slow down the heating of said internal volume of said cold room 100.

Advantageously, the difference between Td and Tn is such that the effective internal temperature Teff of said internal volume remains lower than Tn.

Preferably, the actual internal temperature Teff fluctuates within the defined range between Td and Tn.

Advantageously, the plant 1 comprises thermal energy distribution means which are arranged in said internal volume of said refrigerating chamber 100 and which are configured to transport and distribute cold air, for example from the thermal accumulation means 20, throughout the volume room interior.

Advantageously, said cooling circuit 2 comprises:

- a hydraulic circuit 5, preferably closed, in which at least one cooling fluid flows;

- at least one condenser unit 3, preferably arranged externally with respect to the refrigeration chamber 100 and placed to intercept said hydraulic circuit 5;

- at least one evaporator unit 4 arranged in said internal volume of said refrigerating chamber 100 and placed to intercept said hydraulic circuit 5;

- at least one compressor unit 6 placed to shut off said fluidic circuit 5 downstream of said evaporator unit 4 and upstream of said condenser unit 3; - at least one expansion unit 7, preferably arranged in said internal volume of said refrigerating chamber 100, positioned to intercept said fluidic circuit 5 upstream of said evaporator unit 4 and downstream of the condenser unit 3.

Advantageously, when Teff is greater than Ts, the control means 10 and/or 14 are configured to command the opening of the expansion unit 7 and/or the activation of said evaporator unit 4, thus also causing the activation of said compressor unit 6. Conveniently, in fact, said compressor unit 6 is configured to activate following the opening of said expansion unit 7.

Advantageously, the cooling circuit 2 comprises at least one pressure sensor 60, which is associated or incorporated in said compressor unit 6, and which is configured to detect a decrease in pressure of the cooling fluid in said fluidic circuit 5 following the opening of the expansion unit 7, to thus control the activation/startup (through a transducer or by means of a dedicated control unit) of said compressor unit 6. Conveniently, moreover, the same signal detected by the pressure sensor 60, which is configured to detect a decrease in pressure of the refrigerant fluid in said fluidic circuit 5, following to the opening of the expansion unit 7, is sent to said control means 10 to command and/or thus modulate the frequency of a corresponding inverter 18 connected to the compressor unit 6 at the in order to modulate the activation of the compressor unit 6 itself, preferably to modulate the activation of the compressor unit 6 on the basis of the electric power produced by the electric power supply means 8 of the photovoltaic type.

The present invention also relates to a method for detecting the presence of ice at an evaporator unit of a refrigeration plant which is provided with an evaporator unit comprising an exchanger and/or a fan, said method being characterized in that:

- at least one supply current quantity of said fan is detected by corresponding first sensor means positioned in correspondence with the fan of said evaporator unit and/or at least one pressure quantity is detected by means of corresponding second sensor means positioned in correspondence with the exchanger of said evaporator unit;

- said quantity thus detected is compared with a predefined value or range of values and, on the basis of said comparison, the presence or absence of ice is established.

Preferably, said first sensor means comprise at least one current sensor and in said method at least one electric current supply value of at least one electric motor of said fan is detected and said current value is compared with a preset value obtained from a characteristic curve of absorbed current.

Preferably, in the method according to the invention the presence of ice is established if said electric current value is lower than said predefined value. Preferably, in the method according to the invention said electric current value is detected in various operating situations of said electric motor of said fan and said electric current value is compared with the corresponding operating situation of said absorption characteristic curve.

Preferably, said second sensor means comprise at least one pressure sensor positioned downstream and/or upstream of said evaporator unit or a differential pressure sensor positioned at said evaporator unit, and at least one differential pressure value of a flow of air moved by said fan.

Preferably, said differential pressure value is detected at least upstream and at least downstream of said exchanger of said evaporator unit and/or at least upstream of said exchanger and downstream of said fan of said evaporator unit.

Preferably, in the method according to the invention said differential pressure value is compared with a predefined pressure curve, the presence of ice is established if the pressure downstream of said exchanger is lower than a predefined value and/or if the pressure upstream of said exchanger is greater than that of a further predefined value.

Preferably, in the method according to the invention said pressure and/or current supply quantity of said fan is detected continuously, at a predetermined detection frequency.

Preferably, in the method according to the invention, in the presence of ice or in order to block its formation, the actuation of defrosting means is controlled which are operatively associated with the evaporator unit to thus carry out a defrosting step.

Preferably, in the method according to the invention, in the presence of ice or in order to block its formation, a defrosting phase is carried out by lapping the exchanger of the evaporator unit with a flow of heated fluid, preferably heated by the heat recovered from the condenser unit of the refrigeration system.

DESCRIPTION OF THE FIGURES

The present invention is hereinafter further explained in a preferred embodiment thereof, given for purely exemplifying and non-limiting purposes with reference to the attached sheets of drawings, in which:

Figure A shows a graph of electric absorption, during the hours of a day, by a refrigeration plant according to the state of the art and which, during the day, is supplied with electric energy by a photovoltaic plant;

Figure 1 shows a schematic circuit view of a refrigeration plant according to the present invention;

Figure 2 shows a schematic circuit view of a refrigeration chamber of the plant according to the invention;

Figure 3 shows a top plan view of an embodiment of a refrigeration chamber of the plant according to the invention. DETAILED DESCRIPTION OF THE INVENTION AND SOME PREFERRED EMBODIMENTS ITS

The refrigeration plant according to the invention has been identified as a whole with the reference number 1 in the attached figures.

This refrigeration plant 1 according to the present invention finds advantageous use in the technical sector of the production, marketing and installation of plants configured for storing products at low temperatures, for example refrigeration plants for storing food, medicines or the like.

Preferably, the refrigeration plant 1 is electrically powered by renewable energy sources, in particular by electrical power supply means 8 of the photovoltaic type.

The plant 1 conveniently comprises at least one refrigerating chamber 100 configured to house inside it products to be refrigerated and/or preserved. The refrigerating chamber 100 defines at least one internal volume, intended to be brought to an effective internal temperature that is lower than the ambient temperature outside the refrigerating chamber 100.

Each chamber 100 can comprise two or more cold cells 101 , each defining a corresponding internal volume.

For example, each refrigerating chamber 100 could comprise a refrigerating cell 101 and an anti-cell 102 (with particular reference to the enclosed figure 3).

Advantageously, the anti-cell 102 comprises at least one access door 103 to precisely allow access to the chamber 100 from the external environment. In the same way, conveniently, each cell 101 comprises a corresponding internal door 103' which puts the anti-cell 102 in communication with the cell 101. With reference to the attached figure 3, the refrigerating chamber 100 can comprise two or more cells 101 , for example three cells 101 , each provided with a corresponding internal door 103'.

The plant also comprises a refrigerating circuit 2 operatively connected to the refrigerating chamber 100, and in particular to its internal volume, and configured to cool the air inside the internal volume itself.

Preferably, the refrigeration circuit 2 is connected to each cell 101. Conveniently, each cell 101 is thermally independent with respect to the other cells 101.

Conveniently, the refrigerant circuit 2 can be of the traditional type. In more detail, the refrigerating circuit 2 comprises at least one condenser unit 3, preferably arranged externally with respect to the refrigerating chamber 100 and at least one evaporator unit 4 arranged inside the refrigerating chamber 100, in particular inside each cell 101 , and fluidically connected with the condenser unit 3 and with a compressor unit 6.

Advantageously, the refrigeration circuit 2 comprises a preferably closed fluidic circuit 5 in which at least one refrigerant fluid flows (for example HFC or HFE) and intercepted by the aforementioned evaporator units 4 and condenser 3 and a compressor unit 6. The direction of travel of the refrigerant fluid can be seen from the arrows in the enclosed figure 1.

Conveniently, between the evaporator unit 4 and the condenser unit 3, and in particular downstream of the evaporator unit 4 and upstream of the condenser unit 3, the refrigeration circuit 2 comprises at least one compressor unit 6, preferably arranged externally with respect to the chamber refrigerator 100.

Conveniently, between the condenser unit 3 and the evaporator unit 4, and in particular upstream of the evaporator unit 4 and downstream of the condenser unit 3, the refrigeration circuit comprises at least one expansion unit 7, preferably arranged internally with respect to the chamber refrigerating unit 100 and in particular at or near said evaporator unit 4 and/or inside the evaporator unit 4 itself.

Preferably, the refrigeration circuit 2 comprises two or more compressor units 6, for example three compressor units 6 preferably in parallel, in accordance with the particular embodiment illustrated in the enclosed figure 1.

Advantageously, the system according to the invention also comprises electric power supply means 8, configured to supply electric power to the refrigeration circuit 2.

Preferably, the electric power supply means 8 are of the photovoltaic type. In more detail, the electric power supply means 8 comprise at least one photovoltaic device 9, for example one or more photovoltaic panels and/or photovoltaic fields comprising a plurality of photovoltaic panels. Photovoltaic devices are per se well known to those skilled in the art and therefore not described in detail below.

Conveniently, the electrical power supply means 8 are configured to electrically power corresponding motor means, in particular electric motors, operatively associated with the condenser unit 3, the evaporator unit 4 and the compressor unit 6, for example to drive corresponding pumps and/or or fans in a manner known per se to those skilled in the art. Conveniently, the electrical power supply means 8 are configured to electrically power the opening/closing movement of the valve of the expansion unit 7.

Preferably, the electric power supply means 8 can also provide at least one electric connection with an electric energy distribution network 11 and/or with other traditional electric power generation means (for example diesel generators or others) advantageously placed electrically in parallel with respect to to the photovoltaic device 9.

Conveniently, the electric power supply means 8 are electrically connected to a connection device, for example a general electric switchboard 25, configured to allow the parallel connection of the photovoltaic device 9 and the electric network 11 . Conveniently, the control means 10 can comprise an electronic control unit 10'.

Conveniently, the control means 14 can comprise a secondary electronic control unit

14'.

The system 1 also comprises control means 10 - which preferably comprise a single common electronic control unit for all the rooms 100 and/or a secondary control unit 14' for each room 100 - which are electronically connected (directly or indirectly ) with the components of the refrigeration circuit 2 and, in particular, are electronically connected at least with the expansion unit 7 and the evaporator unit 4. Preferably, the control means are also connected with the compressor unit 6 and/or with the condenser unit 3.

Conveniently, the control means 10 are electrically connected to the electric power supply means 8.

Advantageously, the system according to the invention comprises at least one electronic control unit 10', electrically connected to the electric power supply means 8, and is preferably also electrically connected - directly or indirectly - to the compressor unit 6 and/or to the evaporator 4 and/or condenser unit 3.

Conveniently, the system 1 can comprise at least one sensor 12 which is electrically connected to the electronic control unit 10. The sensor 12 is configured to directly or indirectly detect the production of electric power by the electric power supply means 8 of the type photovoltaic (and in particular from the photovoltaic device 9) and send a corresponding electric/electronic signal to the electronic control unit 10. For example, the sensor 12 could be a solarimeter, i.e. a sensor capable of detecting solar radiation (and therefore to indirectly detect the power production of the device 9, since the electric power generated by the photovoltaic device is proportional to solar radiation) or a wattmeter or even an ammeter, to directly detect the power production of the device 9.

The sensor 12 can be a current sensor associated with the device 9 and/or with a further inverter 13 - which is preferably electrically interposed between the electric power supply means 8 and the general electric switchboard 25 - able to detect the electric current produced by the device photovoltaic 9 and thus send a corresponding electrical signal to the unit 10.

Advantageously, the system can comprise at least a first inverter 18 electrically interposed between said electric power supply means 8 and said compressor unit 6 and also electrically connected to the unit 10' to thus control/modulate/variate the activity of the compressor itself, in particular on the basis of the electric signal that the unit 10' received from the sensor 12 of said electric power supply means 8, i.e. on the basis of the production of electric power by said photovoltaic device 9. Preferably, the first inverter 18 thus controls correspondingly the activation of the compressor unit 6 on the basis of the electric power generated by the power supply means 8 of the photovoltaic type.

Preferably, in a particular embodiment illustrated in the enclosed figures, the electronic control means also comprise further secondary control units 14', in particular at least one secondary control unit 14' electrically connected to a corresponding refrigeration chamber 100 and in particular connected with the evaporator unit 4 of the corresponding refrigeration chamber 100. Conveniently, the secondary control unit 14' is electrically connected to the electronic control unit 10.

In more detail, the control means - and preferably the secondary control unit 14' - are electronically connected to at least one temperature sensor 15, arranged in the internal volume of the refrigeration chamber 100 and configured to detect the actual internal temperature Teff at the inside the refrigeration chamber 100 itself and send to the control means (and preferably to the secondary control unit 14') a corresponding electrical signal representing or containing the aforementioned effective internal temperature value Teff.

Conveniently, each refrigerating chamber 100 and in particular each cell 101 is operatively associated with a corresponding second inverter 24, which is electrically connected to the electronic control unit 10' and which is configured to electrically power motor means capable of operating at least one fan 50 of the evaporator unit 4 in a controlled manner. Conveniently, the second inverter 24 is interposed between said electric power supply means 8 and said evaporator unit 4 and is also electrically connected to the unit 10' to thus control/modulate/variate the activity of the evaporator itself, in particular on the basis of the electric signal that the unit 10' has received from the sensor 12 of said electric power supply means 8, i.e. on the basis of the production of electric power by said photovoltaic device 9. Preferably, the second inverter 24 thus commands corresponding activation of the evaporator unit 4 on the basis of the electric power generated by the power supply means 8 of the photovoltaic type.

Conveniently, a third inverter 59 can be also provided, which is electrically connected to the electronic control unit 10' which is interposed between said electric power supply means 8 and said condenser unit 3 and is also electrically connected to the unit 10' for thus command/modulate/variate the activity of the capacitor itself, in particular on the basis of the electric signal that the unit 10' received from the sensor 12 of said electric power supply means 8, i.e. on the basis of the production of electric power by said photovoltaic device 9. Preferably, the third inverter 59 thus correspondingly controls the activation of the capacitor unit 3 on the basis of the electric power generated by the supply means 8 of the photovoltaic type. Conveniently, the control means 10 and/or 14 are configured to activate the opening of the expansion unit 7 and in particular of one of its expansion valves positioned to intercept the fluidic circuit 5 crossed by the refrigerant fluid.

Conveniently, the control means 10 and/or 14 are configured to also simultaneously control the activation of at least one fan 50 of the evaporator unit 4.

Operationally, the opening of the expansion valve of the expansion unit 7 defines/causes a decrease in the pressure of the refrigerant fluid inside the circuit/duct.

Advantageously, the refrigerant circuit 2 comprises at least one pressure sensor 60, for example at least one pressure switch, which is associated or incorporated with the compressor unit 6. Conveniently, the pressure sensor 60 detects the pressure upstream of the compressor unit 6, and downstream of the expansion unit 7 and/or the evaporator unit 4.

Conveniently, the pressure sensor 60 is configured to detect the decrease in the pressure of the refrigerant fluid downstream of the expansion unit 7, in particular due to the opening of the expansion unit 7.

Advantageously, the pressure sensor 60 is configured to send an activation signal to activate/start at least one compressor of the compressor unit 6 itself. Conveniently, the compressor unit 6 is activated by the pressure sensor 60, and in particular by a control unit which receives the signal from the pressure sensor or from a transducer. Preferably, once the compressor unit 6 has been activated following the decrease in pressure caused by the opening of the expansion unit 7, the control unit 10' then modulates/variates correspondingly, through the first inverter 18, the activation of the compressor unit 6.

The control means - and preferably the secondary control unit 14' - are configured to receive the aforementioned electrical or electronic signal containing the actual internal temperature value Teff and compare it with a reference internal temperature value Ts which is suitably set. The reference temperature value Ts is set by an operator and/or by the electronic control unit 10' and/or by the secondary control unit 14' and defines the reference temperature (set-point) to be reached inside of the refrigerating chamber 100 and in particular inside each cell 101. For purely exemplifying and non-limiting purposes, the reference temperature Ts can be for example between -15°C and -22°C in the case in which the refrigerating chamber 100, and in particular each cell 101 , is of the negative type or the reference temperature Ts can normally be between +4°C and +8°C in the case in which the refrigerating chamber and in particular each cell 101 is of the positive type.

Conveniently, the control means - and preferably the secondary control unit 14' - are configured to calculate a difference value between the actual internal temperature Teff, detected by the temperature sensor 15, and the reference temperature Ts. Advantageously, the control means - on the basis of the difference value thus calculated - thus command a new/different activation of the expansion unit 7 and of the fan 50 of the evaporator unit 4, as described in more detail below. Preferably, the secondary control unit 14', on the basis of the difference value thus calculated, sends a corresponding signal to the electronic control unit 10', which thus defines and commands a new/different activation of the expansion unit 7 and of the fan 50 of the evaporator unit 4, as described in more detail below. Otherwise, in accordance with a further embodiment, the definition of the activation mode of the expansion unit 7 and of the fan 50 can be performed by the electronic control unit 10' alone or by the secondary control unit 14' alone.

Advantageously, as anticipated above, the control means 10 and/or 14, on the basis of the actual internal temperature value Teff, detected inside the refrigerating chamber 100 and in particular the cell 101 , by one or more temperature sensor(s) 15, send a corresponding command signal to command - preferably through the secondary control unit 14' - the activation of the expansion valve of the expansion unit 7 and, preferably, the activation of the fan 50 of the evaporator unit 4 In more detail, during a first period of time corresponding to the daytime hours of the day and/or when the electric power supply means 8 do not generate electric power, the reference temperature value Ts - which is set to a first value Td - is lower than the actual internal temperature value Teff (and therefore the first value Td has not yet been reached), the control means 10 and/or 14 command - or continue to command - the activation (ie the opening) of the expansion unit 7 and activation of fan 50 of evaporator unit 4.

In more detail, the production of electric power by the photovoltaic device 9 during the twenty-four hours of a day defines a bell shape with a peak in correspondence with the central hours of the day (for example between 12 and 14), a moment in which which the sun radiates the most from the photovoltaic device 9.

In this situation, in order to exploit production throughout the production day, the electronic control unit 10' is configured to receive an electrical signal from the sensor 12 associated with the photovoltaic device 9 and an electrical signal from the temperature sensor 15 of the refrigeration chamber 100, and in particular of each cell 101.

Preferably, the reference temperature value Ts is set so as to assume a first value Td during a first period of time and a second value T n, which is different from the first value Td, during a second/distinct period of time. In particular, Ts is set to a first value Td during the day and/or in any case during the period of production of electric power by the photovoltaic device 9, while Ts is set to a second value Tn during the night and/or however during the period of non-production of electric power by the photovoltaic device 9. Conveniently, Td is set so that it is lower than Tn. Advantageously, during the day and/or in any case during the hours in which there is production of energy by the photovoltaic device 9, the reference temperature value Ts is set to a lower value (corresponding to the first value Td), in so that the unit 10', receiving an actual internal temperature signal Teff and comparing this value with that of the first reference value Td, consequently activates the expansion unit 7 and the fans 50 of the unit for much longer evaporator 4, which in turn cause the activation of the compressor unit 6, and this for the purpose of cooling the air present inside the chamber and/or cold room using the electric power generated by the photovoltaic device 9 to approach and/or or thus reach the reference temperature value Td.

Preferably, the first Td value is set so as to be potentially unattainable (in particular the large thermal inertia of the chamber 100 and of the product contained therein effectively makes the first Td value potentially unattainable only during the daytime hours of production of the photovoltaic device 9 ), and this in order to force a constant activation of the compressor unit 6, of the expansion unit 7, of the evaporator unit 4 and of the condenser unit 3, to thus fully exploit the production of photovoltaic power. For example, the first value Td can advantageously be set to a value lower than -22°C for the negative chambers, for example about -25°C. Advantageously, the first value Td is a few degrees lower than the desired and/or suitable temperature for maintaining the products.

In this way, the plant according to the invention allows the photovoltaic production of electric power/energy to be fully exploited, reducing consumption and therefore the costs of supplying it from a traditional electric power supply network.

Furthermore, in order to increase operational flexibility, the plant can comprise (as anticipated above) two or more compressor units 6, and preferably two or more corresponding evaporator units 4 which can be activated or deactivated, in particular by the electronic control 10' independently to vary the electrical power absorption as the photovoltaic production varies.

Advantageously, the operative operation of each compressor unit 6 can be modulated independently on the basis of different irradiation values and/or power values generated by the device 9. In this way, the compressor units 6 are configured to exploit all - or almost - the power produced by the photovoltaic device 9.

In other words, as the irradiation (and/or the power produced) increases, two or more evaporator units 4 are activated, causing a decrease in pressure which is detected by the corresponding pressure sensor to thus activate the corresponding compressor unit 6. In the same way, as the power produced decreases (or as radiation decreases), two or more evaporator units 4 are deactivated, causing an increase in pressure which is detected by the corresponding pressure sensor to thus deactivate the corresponding compressor unit 6. Advantageously, the system can comprise at least one electrical conversion device, for example a further inverter 13, electrically preferably interposed between the electrical power supply means 8 and the general electrical panel 25.

Conveniently, each first inverter 18 associated with the compressor unit 6 and/or each second inverter 24 connected to the evaporator unit 4 and/or the third inverter 59 connected to the condenser unit 3 are preferably connected, for example in data communication, with the electronic control unit 10' to thus allow their control on the basis of the electric power generated by the electric power supply means 8 of the photovoltaic type, in particular in order to optimize the use of the electric power produced by said means according to the characteristic bell.

In more detail, the compressor unit 6 is suitably activated by the pressure sensor 60, in particular following the detection of the decrease in the pressure of the refrigerant fluid. Advantageously, once the compressor unit 6 has been activated, the electronic control unit 10' then controls the operation of the compressor unit 6 by means of a corresponding first inverter 18, for example by controlling any acceleration ramps, in particular on the basis of the power generated by the photovoltaic device 9.

In particular, the first inverters 18 allow to vary the frequency of the supply voltage of the motor means, in particular of the compressor unit 6, to therefore vary its rotation speed and their absorption.

Conveniently, each second inverter 24 and the third inverter 59 operate in a manner corresponding to the first inverter 18 for the evaporator unit 4 and for the condenser unit 3, respectively.

Preferably, in order to minimize the absorption of electric power during the night hours and/or in any case during the period in which there is no production of electric energy by the photovoltaic device 9, the plant comprises thermal accumulation means 20, arranged inside the refrigerating chamber 100 and/or each cell 101 , and preferably equipped with a high specific heat. In more detail, the thermal storage means 20 are configured to release heat and therefore accumulate coolness (thus causing a lowering of its own temperature) during the day and/or when the photovoltaic type electric power supply means 8 produce electric power and/or when the refrigeration circuit 2 is activated , to then absorb heat and then release refrigeration (thus causing its own temperature to rise) inside the chamber during the night and/or when the photovoltaic type electric power supply means 8 do not produce electric power and /o when the refrigerating circuit 2 is deactivated, thus reducing the increase (or the gradient) of temperature inside the compartment 101 itself .

For this purpose, during the night and/or when the electric power supply means 8 of the photovoltaic type do not produce electric power, the control means (ie the electronic control unit 10' and/or the secondary control unit 14') are configured to substantially command the deactivation of the expansion unit 7 and of the evaporator unit 4 (and consequently of the compressor unit 6) to limit the consumption of electric power, or in any case command the activation of the expansion unit 7 and of the evaporator unit 4 (and consequently of the compressor unit 6) only if and when Teff should become greater than Tn.

In more detail, during the night or when the electric power supply means 8 of the photovoltaic type do not produce electric power, the effective internal temperature Teff in the refrigerating chamber 100 remains below an upper threshold temperature, (i.e. a temperature value below above which the products to be stored could be at risk) also thanks to the action of reducing the thermal gradient by the thermal accumulation means 20 which, being at a low temperature, help to absorb heat which tends to penetrate inside the chamber 100 and/or cell 101. Advantageously, the thermal capacity of the thermal accumulation means 20 substantially slows down the heating of the internal environment of the refrigerating chamber 100, in particular even if the refrigerating circuit 2 is deactivated. Preferably, the reference temperature Tn during the night and/or during the period in which there is no production of electric power by the photovoltaic device 9 is set to a value which is higher than the necessary temperature value, for example -18 °C, in order to force the deactivation of the expansion unit 7 and of the evaporator unit 4. In this way, the expansion unit 7 and the evaporator unit 4 are activated only when the Teff temperature inside the chamber is 100 or cell 101 rises above the Tn value, which could reach risk values, in particular too high, for example greater than -18°C, for the products to be preserved while for most of the time, during the night, the vehicles storage devices 20 help to decrease the temperature rise so that the temperature remains below a threshold value.

Therefore, during a first period of time (preferably during the day) and/or when the electric power supply means 8 of the photovoltaic type produce electric power, the setting of a first reference temperature value Td which is lower allows the thermal storage means 20 to lower its temperature sufficiently so that then, during a second period of time (preferably during the night) and/or when the electric power supply means 8 of the photovoltaic type do not produce electric power, the thermal storage means thermal storage 20 can absorb the heat that could penetrate from the outside or be released by the product present in the refrigeration chamber, thus limiting the energy consumption during said second period of time and/or when the means 8 do not produce power, thus keeping the products in an optimal temperature range, for example around -22°C, or in any case below the Tn value (for example around -18°C). In accordance with a particular embodiment, the thermal storage means 20 can be of the passive type, i.e. defined by and/or coinciding with the same products to be preserved, which during the night keep the internal volume of the refrigerating chamber below Tn .

Otherwise, further passive thermal storage means 20 can comprise suitable materials housed in the refrigerating chamber 100. For example, the thermal storage means 20 can comprise ice, or organic or inorganic eutectic materials and/or other materials, such as for example phase change materials (called “ phase change material , PCM).

Conveniently, the thermal storage means 20 can be configured to exploit the latent heat of the phase change of a material, for example a mixture of water and ethylene glycol.

Advantageously, once the desired result of thermal energy storage has been obtained, for example in a given insulated container, it is preferable to distribute this thermal energy inside the chamber/s through thermostatic systems for distributing this energy inside the chambers or affected cells. This distribution can take place for example both with air systems, also conveyed, and with liquids, in particular with a mixture of fluid comprising liquid and/or gas suitable for the temperatures involved.

For example, the system 1 according to the invention can comprise means for distributing the thermal energy inside the refrigeration chamber 100. In accordance with a particular embodiment, the means for distributing the thermal energy comprise fans, for example to the ceiling of the chamber, possibly equipped with a pipe in plastic and/or metallic material (preferably light), used for transporting and distributing the cold air from the heat accumulation zone to the other zones of the chamber 100.

Advantageously, in a possible embodiment, the thermal energy distribution means can comprise circulation pumps for the refrigerated liquid. In particular, this is used for the positive chambers, where the thermal accumulation is carried out outside the chamber and the thermal energy is transported through a pump connected to a convector, i.e. with only the units 50 and 51 in the evaporator 4 , to thus dose this thermal energy through a thermostat which maintains the positive night temperature of the chamber between about +4 and +8°C without the compressor unit 6 starting up.

Preferably, the fans or pumps of the means for distributing the thermal energy are electrically powered at variable frequency in order to dose their flow rate in day/night mode and according to the effective need for distributing force of the cold.

In this way, the system is active and energy-intensive during the hours of sunshine, exploiting the photovoltaic electric power, and almost "dormant" in the hours of low or zero solar radiation, drastically reducing the consumption of electricity. Advantageously, the dosage of the operation takes into account both the obvious variations in solar radiation and the periodic operations of loading/unloading the product from the refrigerating chambers. In order to limit the absorption of electrical energy, the system according to the invention is configured to avoid defrosting phases (known in technical jargon of the sector with the term "defrost") of the evaporator unit 4, in particular to avoid (preferably completely) defrost phases during the night and limit these phases to a minimum during the day.

Advantageously, the system according to the invention is configured to limit the entry of humidity and/or the permanence of humidity inside the refrigerating chamber 100.

For this purpose, the chamber 100 can comprise the aforementioned anti-cell 102, arranged in communication with the external environment through the aforementioned door 103. Conveniently, the anti-cell 102 is partially cooled (eg + 12°C) to reduce the temperature difference between the cells 101 and the external environment. The anti-cell 102 partially blocks the entry of humidity inside the cells 101 but is not able to prevent the formation of humidity inside the anti-cell 102 itself, as it is directly connected with the external environment and due to the moisture released by the products.

The plant 1 advantageously comprises dehumidification means, which are operative associated with said at least one refrigerating chamber 100 and which are configured to remove the humidity inside the chamber itself. Preferably, the dehumidification means housed inside the refrigeration chamber 100.

For example, the dehumidification means may comprise a dehumidification unit, for example installed in the anti-cell 102 and/or inside the cell(s) 101.

Furthermore, the system may include an air curtain system at the doors 103 to reduce the entry of humid air from the outside.

Preferably, the dehumidification means can comprise at least one absorption dehumidifier, more preferably with an absorption rotor, for example of the type marketed by the company "Munters" or under the trade name "Munters". In more detail, dehumidification means of the type with absorption rotor reduce the humidity present in the air, using a hygroscopic and/or absorbent material, ie a material which attracts and retains the water vapor which is then expelled outside.

The dehumidifier comprises an absorbent wheel, made of corrugated material, which contains absorbent material inside it and configured to be crossed by the air to be dried and subsequently by a reactivation air flow. Operationally, the air to be dried passes through the grooves of the material, defined by the wavy shape, coming into contact with the absorbent material. The incoming process air stream releases moisture into the absorbent, so the air leaving the absorbent wheel is dry. The wheel loaded with moisture slowly rotates towards a second exhaust air stream, which has been heated beforehand.

The exhaust air stream, commonly referred to as “reactivation air’’, heats the absorbent. The heated absorbent releases moisture, which is carried away by the reactivation air. The absorbent material that has just dried is introduced again, by rotating, into the process air, where it returns to absorb humidity.

The present invention also relates to a method for detecting the presence of ice at an evaporator. In more detail, the method described below can be advantageously implemented in a refrigeration plant described above which is also an object of the present invention or it can be used in any other plant of any nature which uses an evaporator capable of emitting a flow of air at low temperature.

Therefore, the method described herein finds advantageous use in any type of plant (even if not powered by renewable sources), be it for example for cooling a refrigeration chamber or an air conditioning plant or the like.

Conveniently, all the characteristics described above with reference to the refrigeration plant must also be understood as described with reference to the method for detecting the presence of ice in correspondence with an evaporator operating at negative temperatures.

Conveniently, the method according to the invention is configured to detect the presence of ice at an evaporator unit of a refrigeration system 1 provided with an evaporator unit 4 comprising an exchanger 51 and/or a fan 50.

The method according to the invention provides for:

- to detect at least one supply current quantity of said fan 50 by means of corresponding first sensor means positioned in correspondence with the fan 50 of said evaporator unit 4 and/or to detect at least one pressure quantity by means of corresponding second sensor means positioned in correspondence with the heat exchanger 51 said evaporator unit 4;

- compare said quantity thus detected with a predefined value or range of values and, on the basis of said comparison, the presence or absence of ice is established.

The method provides for the use of at least one sensor which is positioned in correspondence with an evaporator unit and which is able to detect a physical quantity correlated to the presence of ice, in particular in correspondence with an exchanger 51 of the evaporator unit 4. Conveniently, said evaporator unit is equipped with at least one fan suitable for pushing a flow of cold or cooled air.

Preferably, said first sensor means comprise at least one current sensor; in said method at least one electric current supply value of at least one electric motor of said fan 50 is detected and said current value is compared with a preset value obtained from a characteristic curve of absorbed current. In more detail, in accordance with a preferred embodiment, the first sensor means comprises at least one current sensor at motor means which drive the impeller of the fan of the evaporator unit. The current sensor is suitably configured to detect the supply current of these motor means.

The current sensor is advantageously connected electrically or electronically or in any case in data connection with control means (for example with an electronic control unit 10).

Preferably, the current sensor is configured to send an electric detection signal to the control means (for example to the electronic control unit 10) containing the detected current value.

The method therefore provides for a step of comparing the current value thus received by the current sensor with a pre-set value or range of values stored in a memory module of the electronic control unit.

Preferably, the preset current value is obtained from a characteristic load curve, or a characteristic curve of absorbed current, memorized within control means, and in particular within a memory module of the electronic control unit 10.

Subsequently, the method provides for a step for calculating a deviation value, proportional to the difference between the detected current value and the preset value, in particular the corresponding value in the characteristic curve.

The waste value thus calculated is advantageously proportional to the load variation of the electric motor. Normally, the electric motor should work, in a given moment, at a constant speed and with a constant load, since it must rotate the impeller of the fan which has a constant mass over time. Therefore, a variation in engine load indicates the presence of an obstacle in the outlet and/or inlet of the cold air flow, ie in particular the formation of a layer of ice. In more detail, operationally, the formation of the layer of ice at the exchanger 51 of the evaporator unit 4 reduces and/or prevents the entry of air to the fan 50, which tends to increase its rotation speed and reduce the absorption of electric current.

Conveniently, the method provides for establishing the presence of ice if the detected electric current value is lower than a pre-set value.

Advantageously, the method provides for detecting said electric current value in various operating situations of said electric motor of said fan 50 and comparing said electric current value with the corresponding operating situation of said characteristic absorption curve.

Conveniently, the comparison step and the calculation step are carried out by control means (for example by the control unit 10) which, in particular, is correspondingly programmed to carry out these steps.

Therefore, the variation in current absorption is substantially related to the amount of ice formed near or in correspondence with the exchanger 51 of the evaporator unit 4. In this situation, in order to eliminate the ice formed and/or block its formation, the method preferably provides for the activation of defrosting means, which are operatively associated with the evaporator unit.

In other words, the activation of the defrosting means corresponds to a defrosting or "defrost" phase.

In this way, the method according to the invention allows to start the defrosting phase only when it is necessary, ie when the formation of ice is detected, thus reducing useless electrical consumption (for example in the case of electrical defrost).

Advantageously, the defrosting step involves touching the exchanger 51 of the evaporator unit 4 with a flow of heated fluid. Preferably, this fluid is heated by the heat recovered from the condenser unit 3. In more detail, the fluid is heated with the heat of the gas entering the condenser unit 3. In this way, the defrosting phase makes it possible not to consume further energy for produce the heat necessary to defrost the evaporator unit 4.

Advantageously, the provision of recovering the heat from the condenser unit 3 allows the defrosting step to be performed even in the evening or at night without electricity consumption, in particular if there is a hydraulic accumulation of the heated fluid.

Conveniently, to carry out the defrosting, a thermally insulated tank and a circulation pump controlled by the control means can be provided.

Conveniently, the method according to the invention provides for carrying out the defrosting step after each loading of product into the chamber and/or cell (which implies an undesired entry of humidity).

In accordance with a further embodiment, the second sensors comprise two pressure sensors or a differential pressure sensor arranged in correspondence with the fan 50 of the evaporator unit 4, to detect the pressure of the cold air flow, in particular upstream and downstream downstream of the exchanger 51 , moved by the fan 50 itself.

For example, the method according to the invention provides for equipping the evaporator unit with two pressure sensors, in particular a first pressure sensor arranged upstream of the exchanger 51 and a second pressure sensor arranged downstream of the fan 50 or the exchanger 51 of the evaporator unit 4.

The first and second pressure sensors are configured to send corresponding pneumatic and/or electric signals to the electronic control unit 10' containing or representative of the pressure value upstream and downstream of the exchanger 51 of the evaporator unit 4. The method provides then, similarly to the first embodiment, a step of comparing the pressure values with pre-set values.

Following the comparison, if the values deviate from the pre-set values, it means that there is the presence of unwanted ice. In particular, the electronic control unit 10' compares the cold air pressure values detected by the sensors or by the differential sensor with characteristic values, in particular obtained following tests carried out on the particular type of evaporator unit 4.

Conveniently, the method provides for comparing said differential pressure value with a predefined pressure curve, and for establishing the presence of ice if the pressure downstream of said exchanger 51 is lower than a predefined value and/or if the pressure upstream of said exchanger 51 is greater - preferably much greater - than that of a further predefined value .

Preferably, the method provides for continuously detecting the pressure and/or supply current quantities of said fan 50, at a predetermined detection frequency.

The invention thus conceived therefore achieves the intended aims. In fact, as it is clearfrom what has been said, the refrigeration plant according to the invention is particularly advantageous because:

- it makes possible to significantly reduce (typically 20-25%) the consumption of electricity for the same amount of refrigeration produced, in particular by reducing or avoiding - within time intervals greater than one hour or in any case greater than 4 - 5 hours - transients start-stop of the refrigerant circuit compressor unit during which the overall efficiency is lower; moreover, by decreasing the start-stop frequency of the compressor unit, it is also possible to reduce its wear and therefore to increase its useful life,

- it allows optimizing the activation of the components of the cooling circuit based on the electric power produced by the photovoltaic type electric power supply means, in particular by modulating their activation on the basis of the typical bell-shaped pattern of the power produced by the photovoltaic type electric supply means ,

- it allows full use of renewable sources of electrical power with high energy efficiency;

- it is able to maintain a desired temperature inside the cold room or room even in the event of a temporary power failure;

- it uses renewable means of electric power supply and does not necessarily require the use of electric accumulators;

- it is constructively simple and completely reliable;

- it allows to be used continuously throughout an operating day, both during the day and at night;

- it allows a great exploitation of the diurnal use of the photovoltaic device when there is availability of renewable energy;

- it allows to lengthen the operating life of the compressors (since they mainly work with a duty-cycle close to 100%, ie they have much less start/stop);

- it is easily feasible and with low costs; - it is alternative and/or better than the known solutions^-

- it allows to limit management costs, and in particular it allows to limit maintenance costs.

The present invention has been illustrated and described in a preferred embodiment thereof, but it is understood that executive variants can be applied to it in practice, without however departing from the scope of protection of the present patent for industrial invention.