REFRIGERANT

Abstract

Refrigerant for a refrigeration device (1) comprising a gas mixture, said gas mixture comprising at least carbon dioxide, 1,1,1,2-tetrafiuoroethane and difluoromethane, characterised in that carbon dioxide has a mass percentage higher than 50 % in relation to the total mixture.

Claims

1. Refrigerant for a refrigeration device (10) comprising a gas mixture, said gas mixture comprising at least carbon dioxide, 1,1,1,2-tetrafluoroethane and difluoromathane, characterised in that carbon dioxide has a mass percentage higher than 50% in relation to the total mixture.

2. Refrigerant according to claim 1, characterised in that carbon dioxide has a mass percentage between 50% and 75% of the mixture.

3. Refrigerant according to claim 2, characterised in that carbon dioxide has a mass percentage between 67% and 70% in relation to the total mixture, preferably 69%.

4. Refrigerant according to claim 3, characterised in that 1,1,1,2-tetrafluorothane has a mass percentage between 12.5% and 22% in relation to the total mixture, preferably 19%.

5. Refrigerant according to claim 3 or 4, characterised in that difluoromethane has a mass percentage between 9% and 19% of the total mixture, preferably 12%.

6. Refrigerant according to one or more of claims 1 to 5, characterised in that the mass percentage of carbon dioxide, 1,1,1,2-tetrafluoroethane and difluoromethane is such as to make said mixture non-flammable.

7. Refrigeration apparatus (1) equipped with a refrigeration device (10) having a closed circuit (C) within which a refrigerant circulates, said closed circuit (C) being equipped with at least one compressor (2), cooling means (3) for said refrigerant, expansion means (4) for said refrigerant and at least one evaporator (5), characterised in that a refrigerant according to one or more of claims 1 to 6 circulates within said closed circuit (C).

8. Apparatus (1) according to claim 7, characterised by comprising a second refrigeration device (15) having a second closed circuit (C1) within which a second refrigerant circulates, said second closed circuit (C1) being equipped with at least one second compressor (21), second cooling means (31) for said second refrigerant, second expansion means (41) for said second refrigerant and at least one second evaporator (51), wherein said at least one second evaporator is used for cooling the refrigerant circulating within said cooling means (3) of said closed circuit (C), and wherein said second refrigerant is distinct from said refrigerant.

9. Apparatus according to claim 8, characterised in that said second refrigerant comprises R404A, or R449A, or R452A, or other refrigerant having similar thermodynamic properties.

10. Environmentally controlled test chamber (20) having an insulated space (21) within which a specimen (22) to be tested is inserted and comprising a refrigeration apparatus (1) according to one or more of claims 7 to 9.

Description

DESCRIPTION OF THE FIGURES

[0026] Some particular embodiments of the present invention will now be described by way of non-limiting example with reference to the accompanying the FIGURE, which shows a schematic view of the refrigeration apparatus of an environmentally controlled test chamber equipped inside of it with an insulated space within which a test specimen is arranged.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

[0027] The FIGURE shows, in a simplified manner, a refrigeration apparatus 1 equipped with a refrigeration device 10 having a closed circuit C within which a flow rate of refrigerant circulates. The closed circuit C comprises a main compressor 2, at least one cooling device 3 for the refrigerant (in the case of phase change of the refrigerant, also known as a condenser), expansion means 4 of the refrigerant and an evaporator 5. The expansion means 4, which in the particular case comprise an expansion valve of the thermostatic type, in other embodiments may comprise a capillary line or other mechanism, without thereby departing from the scope of protection of the present invention.

[0028] The apparatus 1 further comprises a second refrigeration device 15 having a second closed circuit C1 within which a second refrigerant circulates. Such second closed circuit C1 is equipped with a second compressor 21, second cooling means 31 for the second refrigerant, second expansion means 41 for the second refrigerant and a second evaporator 51. According to the embodiment described herein, the second evaporator 51 is used for cooling and/or condensing the refrigerant circulating within the cooling means 3 of the closed circuit C of the refrigeration device 10. Basically, the apparatus 1 comprises two refrigeration devices 10 and 15, which are cascaded.

[0029] Such refrigeration apparatus 1 is used in an environmentally controlled test (or trial) chamber 20 of the known type and is not described further herein, nor shown in detail in the accompanying figure. Such chamber 20 is equipped with an insulated space 21 where a mechanical specimen 22 to be tested under different environmental conditions, is placed.

[0030] Advantageously, the second refrigerant is distinct from the refrigerant that circulates in the closed circuit C of the refrigeration device 10 and, preferably, comprises R404A. As an alternative to R404A, such second refrigerant may also comprise R449A, or R452A, or other refrigerant having similar thermodynamic properties.

[0031] The refrigerant according to the invention, which instead operates in the refrigeration device 10 within the closed circuit C, comprises a gas mixture. Such gas mixture comprises at least carbon dioxide, 1,1,1,2-tetratluoroethane and diftuoromethane, wherein the carbon dioxide has a mass percentage higher than 50% of the total mixture.

[0032] In particular, according to the embodiment described herein, carbon dioxide has a mass percentage of 69% in relation to the total mixture. In any case, a refrigerant having a mass percentage between 50% and 75% of the total mixture and, preferably, between 67% and 70% of the total mixture, would still fall within the scope of protection of the present invention.

[0033] According to the invention, 1,1,1,2-tetrafluoroethane (or R134a) has a mass percentage of 19%, however in another embodiment the mass percentage of 1,1,1,2-tetrafluoroethane can be between 12.5% and 22% of the total mixture, without thereby departing from the scope of protection of the present invention. Furthermore, difluoromethane (or R32) has a mass percentage of 12% in relation to the total mixture. A mass percentage of the difluoromethane between 9% and 19% of the mixture would however fall within the scope of protection of the present invention.

[0034] Basically, therefore, according to the preferred embodiment described herein, the cooling mixture object of the invention comprises carbon dioxide having a mass fraction of 69% in relation to the total mixture, 1,1,1,2-tetrafluoroethane (or R134a) having a mass percentage of 19% in relation to the total mixture, and difluoromethane (or R32) having a mass percentage of 12% in relation to the total mixture.

[0035] Such a composition has proven to be non-flammable.

[0036] The holder has also experienced that such a refrigerant composition is capable of reaching a temperature well below -57° C. (or even 216.15 K), even down to about -78° C. (or even 195.15 K) within the insulated space 21 of the environmentally controlled chamber 20. Moreover, the refrigerant thus obtained has a very low GWP value, i.e. less than 380 over 100 years. Finally, such refrigerant does not contribute to the expansion of the greenhouse effect.