ES2426347T3 - Refrigerator comprising a beverage dispenser, and method for dispensing a refrigerated beverage - Google Patents

Abstract

A refrigerator comprising a beverage dispenser, the beverage dispenser comprising: a liquid beverage supply pipe (2) hydraulically connected to a water source (3) and including a pressure reducer (9) configured to make the pressure constant water, a gas supply pipe (4) hydraulically connected to a source (5) of pressurized carbon dioxide, at least one mixing device (6) for mixing the gas with the liquid beverage, a port (7) inlet that hydraulically connects the gas supply pipe (4) to the liquid beverage supply pipe (2) or to the mixing device (6) to introduce the gas into the liquid beverage, and a dispensing point (8) for dispense the liquid beverage mixed with gas, characterized in that said inlet port (7) has a cross-sectional diameter of flow between 0.3 and 0.5 mm, so that the resistance of the fluid is generated to reduce the at the rate of gas flow entering the liquid beverage supply line (2) or the mixing device (6) at a predetermined value.

Description

Refrigerator comprising a beverage dispenser, and method for dispensing a refrigerated beverage

The present invention relates to a refrigerator provided with a system and a method of carbonation of water / liquid beverage to dispense a refrigerated beverage. There are different carbonation systems known in the art, which allow the production of carbonated water based on demand.

Commonly, on demand systems use specialized devices, so-called carbonation devices

or "carbonatadores" in line (where the carbonation is carried out at the time of the dispensing of the drink), to combine water and carbon dioxide (CO2) (or any other gas, for example oxygen), or to improve the mix and / or the contact area between them.

US 6,060,092 describes a device for carbonation of drinking water in a continuous in-line process comprising a water supply pipe provided with a pressurization pump adapted to feed an injector nozzle protruding from a hydraulically connected mixing tube to a CO2 supply pipe that has a predetermined low working pressure, in which the CO2 is sucked and then mixed with the water. Because of the high inlet pressure of the injector, the speed of water flow in the nozzle of the injector is increased so much that the CO2 is sucked by the reduced pressure resulting in the end of the nozzle and is delivered under conditions of turbulence to the mixing tube

This online carbonation device is extremely complex. It requires high pressure in the water supply pipe and low pressure in the CO2 supply pipe and as a greater requirement, a difference between such pressures is necessary in order to ensure the effective operation of the carbonation device. Therefore, the correct balance of pressures must be maintained during the use of the system.

WO 98/47812 describes a water carbonation system comprising a source of pressurized CO2 connected to a gas pipe having a flow limiter adapted to deliver CO2 at a predetermined pressure above that of water to an accessory in T. A pump is connected to a source of drinking water and serves to pump water along the water pipe to the T-fitting. CO2 and water are initially mixed in the T-fitting and they flow through of an in-line carbonation device and along the carbonated water pipe to the dispensing point.

Other systems on demand, as described in WO 2005/105279 and WO 2006/114086, use an in-line carbonation device comprising structures filled with bulky material to improve the mixture between CO2 and water.

A drawback of these carbonation systems is that a predetermined and precise gas working pressure value with respect to the liquid working pressure value is required at the liquid / gas mixing point to effectively introduce the gas into the liquid.

In practice, the carbonation system has to supply the gas to the liquid / gas mixing point with a predetermined pressure value according to the pressure value of the liquid that is delivered to the liquid / gas mixing point.

For these reasons, the CO2 supply pipe of these carbonation systems includes a check valve disposed upstream of the liquid / gas mixing point to precisely control and adjust the gas pressure value on the installation of the gas system. carbonation and to maintain such a constant pressure value during the use of the latter. Therefore, these carbonation systems are not very flexible and need continuous adjustment.

Another drawback of these carbonation systems is that a high liquid pressure value is necessary at the liquid / gas mixing point to reach a satisfactory level of carbonation. Therefore, the liquid supply line must include a pressurization or pressure lift pump disposed upstream of the liquid / gas mixing point in order to increase the pressure value of the liquid to be carbonated.

It is clear that all these pressure requirements make these carbonation systems complex and expensive. In addition, the components, which have to be used in order to meet the aforementioned pressure requirements (pumps and regulating valves), make these carbonation systems unreliable and subject to malfunctions.

US-A-4,915,261 describes a carbonated beverage dispensing system for dispensing a mixed beverage consisting of a flavoring constituent contained in an individual service package and a base liquid. The dispensing system includes a drive unit that has a plate that is movable between a retracted position in which a package containing the flavoring constituent can be placed in the drive unit with a discharge end thereof that can be broken directed. down and an actuated position that progressively presses against one side of the package to force the contents of the package downward to break the discharge end of the package and to expel the contents thereof to a discharge nozzle. A carbonated water supply is provided to simultaneously dispense a predetermined amount of carbonated water to the nozzle to mix with the expelled flavoring constituent before discharging both. The carbonated water supply is adapted to carbonate fresh water substantially instantaneously when it is being dispensed to the mixing nozzle.

GB-A-1,441,658 describes a water carbonation device comprising, in the direction of the water flow, a first stage in which the CO2 is extracted from a source at a pressure lower than that of the water by suction in water and partially absorbed in it, and a second stage in which water with partially absorbed CO2 is accelerated, to decrease static pressure and increase turbulence, so that the surface area of water exposed to CO2 is increased to achieve a substantially complete CO2 absorption. Preferably, the water pressure is 6.28-6.63 bar, the CO2 pressure is 0.14-0.35 bar less than the water pressure, and the water temperature is between 0-4.44º C A stage is provided comprising an annular chamber that receives CO2 through an inlet port, an inner chamber that receives CO2 from a chamber through radial ports, and axial water flow passages that communicate with an inlet port. of water and each of which cuts at least one step of radial CO2 aspiration. The stage comprises a conical chamber having a wall narrows to a throat that communicates with a collection chamber. The narrowing angle of the wall is preferably less than 45. The cross-sectional area of the water inlet port exceeds the total cross-sectional area of the passages which in turn exceeds the cross-sectional area of the throat. In operation, the water that passes through the passages extracts radial CO2 in and out respectively of the chambers, causing the dragging of CO2 molecules a turbulence of the water flow and a partial absorption of CO2. The streams of water expelled from the passages are made to strike the chamber wall and are then combined in the throat to enter the collection chamber, causing acceleration towards the throat a decreased static pressure and increased turbulence. In the arrangement of fig. 1, water from a reservoir is pumped through a line cooler that has carbonation devices arranged in parallel. The pressure in the pipe is determined by a pressure regulating valve relieving atmospheric pressure. Alternatively, the pump may be disposed downstream of the cooler, and the latter may cool the water while it is in the reservoir. The valve and a CO2 pressure regulation valve are operatively interconnected. The output from each distributor comprises an open stop key push button that can be fixed directly to the body of the carbonation device. The cooled water and CO2 can be fed to the carbonation devices through flexible pipes. The cooled pressurized water for the carbonation device can be provided from a coil in a conventional refrigerator, or on the wall thereof.

US-A-3,761,066 describes an in-line water carbonation device that introduces CO2 and fresh water into a conduit that leads to a carbonated water dispensing valve each time the valve is opened. The CO2 and water are completely mixed in the duct when carbonated water is dispensed through the valve so that water is charged with CO2 when it is dispensed.

EP-A-1,614,986 describes a refrigerator door with a carbonation device installed therein and includes a heating device provided in an interior part of the refrigerator door, to supply heat to the carbonation device. The refrigerator door also includes a temperature sensing device for measuring a temperature of the carbonation device and then generating a signal indicating the measured temperature; and a controller for controlling the heating device according to the signal from the temperature sensing device. If the temperature of the carbonation device is less than, or equal to, a programmed operating temperature, the controller controls the heating device to generate heat.

EP-A-1,580,502 describes a refrigerator capable of manufacturing a carbonated water that includes a water container, a mounting area for mounting the water tank therein, and a dispensing unit for carbonating the water in the water container. water, the water area having a variable vertical distance. In addition, the mounting area has a first area with a specific height and a second area with a predetermined height formed under the first area, the second area being open selectively to communicate with the first area.

It is therefore a main object of the present invention to provide a refrigerator, which is effective in reducing the aforementioned drawbacks of the aforementioned prior art.

In accordance with the present invention, this objective, together with others that will be apparent in the following description, is achieved by a refrigerator according to claim 1, and a method for dispensing a refrigerated beverage according to claim 12.

The features and advantages of the present invention will in any way be more readily understood from the description given below with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view of a refrigerator according to the present invention;

Fig. 2 is a schematic view of a refrigerator according to another embodiment of the present invention;

Fig. 3 is an enlarged sectional view of the carbonation inlet port of fig. one;

Fig. 4 is an enlarged sectional view of the carbonation inlet port of fig. 2;

Fig. 5 is a graph showing the CO2 concentration of the liquid beverage dispensed as a function of the CO2 working pressure value in bar with and without the carbonation inlet port of figs. 1 and 3;

Fig. 6 is a graph showing the CO2 concentration of the liquid beverage dispensed as a function of the CO2 working pressure value in bar with and without the carbonation inlet port of figs. 2 and 4;

With reference to the aforementioned figures, the beverage dispenser, as generally indicated by reference number 1, of the refrigerator comprises a liquid drink supply pipe 2 hydraulically connected to a water source 3, a supply pipe 4 of carbon dioxide connected hydraulically with a source 5 of pressurized carbon dioxide, at least one mixing device 6 for carbonating the liquid beverage, a carbonation inlet port 7 that hydraulically connects the carbon dioxide supply pipe 4 to the supply line 2 for the liquid beverage or to the mixing device 6 for introducing carbon dioxide into the liquid beverage, a dispensing point 8 for dispensing the carbonated liquid beverage.

The carbonation inlet port 17 has reduced the cross section of the flow to generate frictional resistance adapted to reduce the flow rate of carbon dioxide entering the liquid beverage supply line 2 or the mixing device 6 to a default value.

The liquid beverage supply line 2 of the beverage dispenser can be connected directly to the water supply network (for example the municipal water supply networks) through a suitable connection or alternatively the water source 3 can have the form of a pressurized deposit. The normal water pressure of the building is sufficient.

The liquid beverage supply line 2 connects the water source 3 with a water pressure reducer 9 which is adapted to reduce the water pressure to a specified working pressure value, for example from 2 to 3 bar, with the in order to have the same starting conditions for the treatment procedure regardless of the pressure value of the water supply networks.

In practice, the water pressure reducer 9 makes the incoming water pressure value constant so as to avoid the problems connected to the pressure value fluctuations that normally affect the municipal water supply networks.

In an embodiment that is not part of the present invention, it can however be more readily appreciated than in the case where water is supplied by a pressurized reservoir, there is no need for a pressure reducer, since the pressurized reservoir is adapted to feed the liquid water supply pipe with water having a constant pressure value, for example from 2 to 3 bars, as in the aforementioned embodiment which includes the pressure reducer hydraulically connected to the municipal water supply networks.

Convenient, but not necessarily, a cooling unit 10 is provided to cool the liquid beverage to be carbonated or the carbonated beverage to be dispensed.

Preferably, the cooling unit 10 is hydraulically connected to the water source 3 by the liquid beverage supply line 2 and is provided upstream of the carbonation inlet port 7 in order to lower the temperature of the liquid beverage with the in order to improve the amount of carbon dioxide that can be dissolved in the liquid beverage. As is known, the lower temperature improves the ability of water to absorb carbon dioxide.

The cooling unit 10 may be a compression cooling system that operates in a known manner, in particular with compressor, evaporator, and condenser. Alternatively, a Peltier cooling system or other known cooling system can be used.

In addition, the liquid beverage supply line 2 may comprise at least one filter device for filtering the liquid beverage to be delivered to the carbonation inlet port 7.

Preferably, a check valve 11 is provided in the liquid beverage supply line 2 just upstream of the carbonation inlet port 7, where carbon dioxide is introduced into the liquid beverage, in order to prevent the liquid beverage from flowing back to the cooling unit 10.

The carbon dioxide supply pipe 4 extends from the pressurized CO2 source 5 to the carbonation inlet port 7 and comprises a CO2 pressure reducer 12 to reduce the pressure of the gas flowing through the supply pipe 4 of carbon dioxide below an upper limit, for example 7 bar in order to ensure safe working conditions of the beverage dispenser according to the present invention.

The carbon dioxide supply line 4 comprises an electrovalve 13 disposed downstream of the CO2 pressure reducer 12 and adapted to selectively connect the pressurized source of CO2 with the carbonation inlet port 7 in order to produce carbonated liquid drink when required. Advantageously, the solenoid valve 13 is adapted to control and adjust the amount of CO2 to be supplied to the carbonation inlet port 7 so that the CO2 content of the liquid beverage to be dispensed can be varied according to the desired level selected by the user.

Preferably, a check valve 14 is provided in the carbon dioxide supply line 4 between the solenoid valve 13 and the carbonation inlet port 7 to prevent CO2 from flowing back to the solenoid valve

13.

In the embodiments described herein for purely exemplary purposes, the working pressure of the water, downstream of the water pressure reducer 9, has a value of 1.5 to 3 bar depending on the intake pressure available from the networks Urban water supply, which in some country can be particularly low, around 2 bar.

In this connection, the pressurized reservoir simply ensures that the slightly pressurized water of 1.5 to 3 bar, as in the case of the liquid beverage supply line 4 is directly connected to the water supply networks, is delivered to the point of liquid / gas mixing in which carbonation takes place. In fact, it would be preferable for the carbonation to be carried out with better results (high carbonation level) a water pressure value slightly higher than the atmospheric pressure value.

With respect to the carbon dioxide side, in the embodiment described herein for purely exemplary purposes, the working pressure value of the CO2 gas may vary in a range of 2 to 7 bar.

The refrigerator according to the present invention includes at least one section 15 of mixing the liquid / gas in which the carbon dioxide is mixed with the liquid beverage. In particular, the carbon dioxide supply pipe 4 comprises a carbonation inlet port 7 that is adapted to supply the CO2 flow to the liquid / gas mixing section 15 for the carbonation to be carried out.

In a first configuration of the present invention (see Figs. 1 and 3) the liquid / gas mixing section 15 comprises a junction point where the carbon dioxide supply pipe 4 intercepts or hydraulically joins the liquid drink supply pipe 2 through the carbonation inlet port 7 in order to allow the CO2 to be introduced into the liquid beverage supply line 2 and therefore be mixed with the liquid beverage.

In addition, the liquid / gas mixing section 15 comprises a mixing device 6 which has to be fed with the liquid / gas mixture emerging from the junction point in order to complete the CO2 absorption and then increase the final carbonation level.

In practice, the junction point acts as a three-way connector in which the carbon dioxide flow and the liquid beverage flow flow together and the resulting mixture flow is delivered to the mixing device 6.

In a second configuration of the present invention (see Figs. 2 and 4) the liquid / gas mixing section 15 comprises a mixing device 6 hydraulically connected with the liquid beverage supply pipe 2 by means of a suitable connection fitting and to the pipe 4 for supplying carbon dioxide through the carbonation inlet port 7, which is adapted to introduce carbon dioxide directly to the mixing device 6.

The cross-sectional flow section of the carbonation inlet port 7 has a chosen diameter dimension, after extensive tests or tests, so that the frictional resistance of the fluid is generated (when the CO2 flows) which is adapted to reduce the speed of the flow of carbon dioxide that passes through the carbonation inlet port 7 and enters the liquid beverage supply line 2 or the mixing device 7.

In practice, the frictional force of the fluid tends to decrease the flow rate of CO2 to a reduced predetermined value, which is a substantially constant value, almost independently of the pressure value of the carbon dioxide that passes through the inlet port 7 of carbonation.

In addition, increasing the length (ie longitudinal extension perpendicular to the cross section of the inlet port) of the reduced carbonation inlet port 7 will also decrease the amount of gas that is allowed to pass at each moment.

Therefore, the working pressure value of carbon dioxide can vary widely during the operation of the beverage dispenser without affecting the velocity of the CO2 flow entering the liquid beverage supply line 2 or the mixing device 6

The reduced rate of CO2 flow allows the gas to mix effectively with the liquid beverage so as to maximize the absorption of carbon dioxide within the mixing device.

In this way it is possible to reach a high level of carbonation despite the fact that the working pressure value of carbon dioxide does not remain constant during the use or operation of the beverage dispenser or even if it varies over a wide, extensive range and even in addition if the working pressure of carbon dioxide has not been correctly established during the installation of the refrigerator according to the present invention or due to the variation or change of the component.

In other words, there is no need to precisely control or adjust the working pressure of CO2 at the time of installation or during use of the refrigerator.

It has been found that the friction resistance of the fluid adapted to decrease the flow rate of carbon dioxide is generated using a carbonation inlet port having a cross-sectional diameter of flow between

0.3 and 0.5 mm.

For both of the aforementioned configurations, the carbon dioxide supply pipe 4 is comprised of a conduit having an internal diameter of less than 20 mm and a preferred diameter range of 6 to 8 mm. However, it can be seen more easily that the dimensions of the previous diameter of the carbon dioxide supply pipe 4 upstream of the carbon inlet port 7 serve only to optimize and maximize the effect of fluid friction resistance determined by the limitation or restriction of port 7 of carbonation input.

It is well known that according to Bernoulli's theorem of compressible fluids that the decrease in the internal diameter of a port causes the increase in the velocity of the fluid flowing through it.

However, it has been experienced that below a certain diameter dimension, the frictional resistance generated by the inner wall surfaces of the port is so high that they reduce the flow velocity and, as described above, such velocity is substantially constant. despite fluid pressure (at least for a given pressure range). This is called strangled flow.

There is clearly a lower limit of the diameter dimension below which the fluid is completely prevented from passing through the port, only an extremely high working pressure would force the fluid to circulate.

With respect to the first configuration of the present invention, in which the carbon dioxide supply pipe 4 intercepts or hydraulically joins the liquid drink supply pipe 2 through the carbonation inlet port 7 and the mixing device is fed with the mixture of liquid / gas that emerges from the point of attachment, a series of tests have been carried out that lead to the graph shown in fig. 5 where the Y axis represents the CO2 concentration of the liquid beverage dispensed in grams per liter and the X axis represents the CO2 working pressure value in bar (the experimental points of the graph are obtained for a working water pressure of 2 bar)

It is clear that with a conventional carbonation inlet port (2-6 mm) an effective carbonation can be achieved (in order to produce a full bubble drink) only if the CO2 working pressure value is approximately 1.7 -2 bar, outside of such range the concentration of CO2 falls rapidly below 5 g / l.

On the other hand, using a carbonation inlet port that has an internal diameter of approximately 0.4 mm, the CO2 concentration remains above 5 g / l for a CO2 working pressure of 2 to 3.7 bar and above 5.5 g / l for a CO2 working pressure of 2.3 to 3.2 bar.

Using also a carbonation inlet port having an internal diameter of approximately 0.3 mm, the CO2 concentration remains above 5 g / l for a CO2 working pressure of 3 to 6 bar.

It can be fully appreciated that the present invention allows the CO2 working pressure to vary within a wide range without adversely affecting the final CO2 concentration of the dispensed beverage and therefore, a pressure value adjustment is not required. of CO2 work.

In addition, according to a preferred embodiment of the present invention, the carbon dioxide supply line 4 and the liquid beverage supply line 2 are reciprocally arranged so that the gas flow enters the supply line 2. of liquid beverage through the carbonation inlet port 7, it has at least one vector component of the velocity vector oriented in the opposite direction of the liquid flow in order to improve the turbulence and hence the contact surface of the liquid / gas .

In particular, at the carbonation inlet port 7 the carbon dioxide supply line 4 and the liquid beverage supply line 2 form an angle V of 90 ° to 180 ° and preferably approximately 135 °.

The liquid / gas mixture emerging upstream from the carbonation inlet port 7 is then supplied to the mixing device 6 by means of a suitable accessory 15.

A carbonated beverage supply line 17 hydraulically connects the mixing device 6 with the dispensing point 8.

The dispensing point 8 includes an outlet valve 18 for dispensing the carbonated beverage. The operation of the outlet valve 18 causes simultaneous opening of the solenoid valve 13.

Optionally, a compressor can be provided in correspondence with the dispensing point 8 so that the carbonated beverage can be emitted with a pleasant jet.

With respect to the second configuration of the present invention, in which the carbon dioxide supply pipe 4 is hydraulically connected directly to the mixing device 6 through the carbonation inlet port 7, which is adapted to introduce carbon dioxide directly to the mixing device, a series of tests have been carried out that lead to the graph shown in fig. 6 where the Y axis represents the CO2 concentration of the beverage dispensed in grams per liter and also the flow rate of liquid dispensed in liters per minute, the X axis represents the value of CO2 working pressure in bar (the experimental points of the graph they are obtained for a working water pressure of 2 bar).

Using a conventional carbonation inlet port (2-6 mm) the CO2 concentration remains above 5.5 g / l for a CO2 working pressure of 3.7 to 4.7 bar. However, as shown in the lower part of the graph, the flow rate of the dispensed liquid decreases rapidly when the CO2 working pressure exceeds 4 bar and above 4.7 bar the flow rate is extremely low.

Using a carbonation inlet port having an internal diameter of approximately 0.4 mm, the CO2 concentration remains above 5.5 g / l for a CO2 working pressure of 4.2 to 7, while the Flow rate begins to decrease slightly when the CO2 working pressure is above 5.5 and up to 7 bar of CO2 working pressure the flow rate is still high enough for the refrigerator to operate effectively.

It can be fully appreciated again that the present invention allows the working pressure of CO2 to vary within a wide range without adversely affecting the final CO2 concentration of the dispensed beverage and therefore, no adjustment of the value of CO2 working pressure.

The mixing device 6 may comprise any turbulence structures adapted to produce the largest possible contact surface of CO2 / liquid in order to facilitate CO2 absorption.

In the case of the first configuration according to the present invention, the turbulence structures are adapted to mix the flow of carbonated liquid drink and the free CO2 to further improve the combination thereof.

In a preferred embodiment, the mixing device 6 comprises a rotor that has a plurality of blades or vanes and adapted to rotate within a chamber.

In accordance with the first or second configuration of the present invention, the liquid / gas mixture or the flow of liquid drink without gas entering the chamber causes the rotor to be rotated in order to carry out the carbonation.

In another preferred embodiment, the mixing device comprises a positive displacement pump and in particular a diaphragm pump or a gear pump that has been found that is adapted to effectively carry out the carbonation process.

It can easily be seen that in the case of the last described embodiment, the operation of the outlet valve 17 causes simultaneous opening of the solenoid valve 13 and that the positive displacement pump operates.

It should be stressed that according to the present invention, the working pressure of liquid drink downstream of the water pressure reducer 9 may also be higher than 3 bar, in some countries, in fact, the inlet pressure available from the Municipal water supply networks is around 4-5 bar and also about 6 bar.

The extreme values of the CO2 working pressure range are determined by the fact that below 2 bar, an extreme mixing occurs or no liquid / gas mixing occurs, while above 7 bar the beverage is prevented liquid reaches the liquid / gas section 15 and therefore the carbonation inlet port 7.

In accordance with the present invention, the water working pressure value may be higher or lower than the CO2 working pressure value corresponding to the carbonation inlet port 7 depending on the dimensions of the nozzle, the characteristic Hydraulic fluid circuit and in-line carbonation device.

Optionally, the beverage dispenser of the refrigerator according to the present invention may be in the form of a dispenser with rear mixing adapted to mix syrup or concentrate to the water without gas or carbonated to produce beverages of different flavors in which the mixing is brought to out at the time of dispensation. For this purpose, the beverage dispenser comprises a plurality of tanks containing syrups or concentrates that are to be mixed with water. The concentrate tanks may be hydraulically connected to the liquid beverage supply line 2 or carbonated beverage supply line 17 in order to introduce the concentrate into the water without gas, that is upstream of the liquid section 15 / gas, or carbonated water, that is downstream of the liquid / gas section 15.

The refrigerator according to the present invention provides a carbonation system that uses few components, simple and low cost, that do not need particular requirements about its adjustment, operation and maintenance.

In conclusion, it can therefore be affirmed that the carbonation system provided in the refrigerator according to the present invention is completely effective in solving the problems connected with the prior art systems in a simple manner.

Claims (13)

1.- A refrigerator comprising a beverage dispenser, the beverage dispenser comprising: a liquid beverage supply pipe (2) hydraulically connected to a water source (3) and which includes a pressure reducer (9) configured to make the water pressure constant, a gas supply pipe (4) hydraulically connected to a source (5) of pressurized carbon dioxide, at least one mixing device (6) for mixing the gas with the liquid drink, an inlet port (7) that hydraulically connects the gas supply pipe (4) to the liquid beverage supply pipe (2) or to the mixing device (6) to introduce the gas into the liquid beverage, and a dispensing point (8) for dispensing the liquid beverage mixed with gas, characterized in that said inlet port (7) has a cross-sectional diameter of flow between 0.3 and 0.5 mm, so that the resistance of the fluid is generated to reduce the velocity of the gas flow entering the supply pipe (2) of liquid beverage or in the mixing device (6) at a predetermined value. 2. A refrigerator according to claim 1, wherein said mixing device (6) is adapted to be fed with the liquid / gas mixture emerging from a junction point where the gas supply pipe (4) joins hydraulically to the liquid drink supply pipe (2) through the inlet port (7), or intercept it. 3. A refrigerator according to claim 2, wherein the gas supply pipe (4) and the liquid beverage supply pipe (2) are arranged reciprocally so that the gas flow, which enters the liquid beverage supply pipe (2) through the inlet port (7), has at least one vector component of the velocity vector oriented in the opposite direction of the liquid beverage flow in order to improve turbulence and hence the liquid / gas contact surface. 4. A refrigerator according to claim 3, wherein in the inlet port (7) the gas supply pipe (4) and the liquid beverage supply pipe (2) form an angle V of 90 ° to 180 ° and preferably about 135 °. 5. A refrigerator according to claim 1, wherein said mixing device (6) is hydraulically connected to the liquid beverage supply pipe (2) by means of a liquid beverage connection and to the pipeline

(4)

 of gas supply through the port (7) of entry.

6. A refrigerator according to any one of the preceding claims, wherein said mixing device

(6)

 It comprises a rotor that has a plurality of blades or vanes.

7. A refrigerator according to any one of the preceding claims, wherein said mixing device

(6)

it comprises a positive displacement pump and in particular a diaphragm pump or a gear pump.

8. A refrigerator according to any one of the preceding claims, wherein said liquid beverage supply pipe (2) is connected to the municipal water supply network or alternatively the water source (3) is a pressurized reservoir. 9. A refrigerator according to any one of the preceding claims, wherein the gas supply pipe (4) comprises an electrovalve (13) adapted to selectively connect the source (5) of pressurized gas to the port (7) inlet, to control and adjust the amount of gas to be supplied to the inlet port (7). 10. A refrigerator according to any one of the preceding claims, comprising a subsequent mixing dispenser for introducing syrup or concentrate in the water without gas upstream of the mixing device (6), or in the water mixed with gas downstream of the mixing device (6). 11. A refrigerator according to any one of the preceding claims, wherein a cooling unit (10) It is intended to cool the liquid beverage in which the gas is to be introduced or the liquid beverage mixed with gas to be dispensed. 12.- A method for dispensing a chilled beverage, comprising:

-

 supply a liquid drink from a water source with a constant pressure,

-

 supply a gas from a source of pressurized gas, in which the gas is carbon dioxide,

-

 mix the gas with the liquid drink,

-

 reduce the cross section of the gas flow before the gas is mixed with the liquid beverage by passing the gas flow through an inlet port having a cross-sectional diameter of the flow comprised

5 between 0.3 and 0.5 mm, so that the fluid resistance is generated to reduce the gas flow rate to a predetermined value and dispense the liquid drink mixed with gas. 13. A method according to claim 12, wherein the working pressure value of the liquid beverage into which the gas is to be introduced is 1.5 to 7 bar. 14. A method according to claim 12, wherein the working pressure value of the gas to be supplied to the inlet port is 2 to 7 bar.