CN1279139C - Substitute refrigerant for freon-12 centrifugal cold water machine set - Google Patents

Abstract

The present invention relates to a refrigerant for a centrifugal water chilling machine set, particularly to a substitute refrigerant for a freon-12 centrifugal water chilling machine set. The refrigerant contains monochloro difluoro methane, 1, 1, 1, 2, 3, 3, 3-heptafluoropropane and 1-monochloro-1, 1-difluoroethane and isobutane can be optionally added to form a quaternary mixture. The refrigerant is prepared by physically mixing the ingredients in a liquid phase state according to corresponding proportions. The refrigerant has the advantages of environmental protection, high safety and reliability, equivalent refrigerating efficiency to that of CFC-12, no need for changing the compressor and the main parts of the system and reforming the production line and direct filling, has slightly better performance than that of freon-12, and can be used as a substitute refrigerant for the existing freon-12 centrifugal water chilling machine set.

Description

An Alternative Refrigerant for Freon-12 Centrifugal Chiller

technical field

The invention belongs to a refrigerant, in particular to a refrigerant used in a centrifugal chiller.

Background technique

Freon-12 (CFC-12) has been widely used in refrigeration systems and other fields for a long time because of its low toxicity, non-flammability, non-corrosion, and compatibility with other materials. However, since it was discovered in 1974 that CFC substances have a serious damage effect on the atmospheric ozone layer, it has attracted increasing international attention, and it has been decided to gradually limit the production and use of CFCs. my country will stop using CFC-12 on January 1, 2010. At present, as the refrigerant of centrifugal chillers, the use of CFC-12 still accounts for a considerable proportion.

The parameters such as impeller speed and impeller basic size of CFC-12 centrifugal compressor are determined according to certain evaporation temperature, condensation temperature, thermophysical properties and molar mass of refrigerant CFC-12. Generally speaking, CFC-12 centrifugal chillers can only use CFC-12 as a refrigerant. If other refrigerants are used, due to the difference in thermophysical properties and molar mass between the substitute and CFC-12, not only cannot achieve The efficiency of the original centrifugal chiller may not even work properly. When switching to some other alternatives, such as HFC-134a, it is necessary to modify the compressor impeller or replace some parts. Therefore, it is much more difficult to choose an alternative refrigerant for CFC-12 centrifugal chillers than piston and screw chillers. It not only requires similar thermal properties to CFC-12, but also has special requirements.

At present, HFC-134a is the main refrigerant to replace CFC-12. Its advantage is that it does not destroy the ozone layer, and its thermal performance is very similar to that of CFC-12. However, since the molar mass of HFC-134a is 102.03, that of CFC-12 The molar mass is 120.91, due to the difference between their molar masses, when directly filling, the blade tip speed must be increased by about 15% compared with CFC-12, so the impeller and transmission gear must be replaced, and the tubes of the heat exchanger must be rearranged , the cost will increase significantly. Otherwise, the compressor will surge and cannot work normally when running at full load. In addition, some mixture substitutes for CFC-12 have been developed at home and abroad, such as R401 series, R406A, THR01 and THR02, etc. When these mixture substitutes replace CFC-12 in piston and screw chillers, the operation effect All good, but when used in a centrifugal chiller, due to the difference in molar mass, if the size and size of the impeller are not changed, not only the cooling effect of the original CFC-12 cannot be achieved, but the chiller may not work properly. At present, there is no refrigerant substitute that can be directly used in CFC-12 centrifugal chillers at home and abroad without modifying its equipment.

In the patent PCT/US96/14882, a kind of 21%-75% HCFC-22, 15%-60% HFC-227ea, 5%-25% HCFC-142b and 1%-10% The quaternary mixture composed of 600a is used as a substitute for CFC-12. However, according to the previous description, the centrifugal chiller has special requirements on the thermal performance and molar mass of the refrigerant. The molar mass of the substitute must be close to that of CFC-12 (120.91), and the inlet and outlet pressure must be similar to that of CFC-12. Rather, factors such as flammability and refrigeration performance need to be considered comprehensively, and not any ratio of the above-mentioned quaternary mixture is suitable for centrifugal chillers. For example, the various ratios mentioned in its patent examples: "R-600a/142b/227ea/22 of 4/15/40/41, R-600a/142b/227ea of 4/15/30/51 /22, R-600a/142b/227ea/22 on 8/13/38/41, R-600a/142b/227ea/22 on 2/16/41/41, R-600a on 4/20/45/31 /142b/227ea/22 and 4/8/32/56 of R-600a/142b/227ea/22", their molar masses are 107.8, 101.6, 103.7, 110.0, 112.2 and 101.6 respectively, all of which are the same as those of CFC-12 The difference in molar mass (120.91) is relatively large, and it cannot be directly filled and used in existing centrifugal chillers at all. As another example, choose 40% HCFC-22, 40% HFC-227ea, 15% HCFC-142b and 5% HC-600a to form a mixture within the scope of the claims, and its molar mass is 107.16, which is higher than that of CFC-12 The molar mass is 11.4% smaller, and it cannot be directly filled and replaced; select 21% of HCFC-22, 55% of HFC-227ea, 22% of HCFC-142b and 2% of HC-600a to form a mixture, and its molar mass is 122.0, which is equivalent to the molar mass of CFC-12, but its volumetric refrigeration capacity is only 90.5% of that of CFC-12. Therefore, the scope of claims of this patent is not applicable to centrifugal chillers.

Contents of the invention

The present invention aims to develop a new refrigerant for centrifugal chillers, which is a substitute for existing CFC-12 centrifugal chillers, so that it not only meets environmental protection requirements, but also is safe, reliable, and has refrigeration efficiency comparable to that of CFC. It is equivalent to -12, and it can be filled directly without changing the existing equipment and refrigeration oil.

The present invention is achieved through the following technical solutions:

An alternative refrigerant for Freon-12 centrifugal chillers, characterized in that the refrigerant contains chlorodifluoromethane, 1,1,1,2,3,3,3-heptafluoropropane and 1-chloro-1, 1-difluoroethane three substances, the content (mass percentage) of each component is

Chlorodifluoromethane: 28-30%

1,1,1,2,3,3,3-Heptafluoropropane: 60%-62%

1-Monochloro-1,1-difluoroethane: 10%-12%

The three component contents (mass percentage) of the above-mentioned refrigerant are:

Chlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-Heptafluoropropane: 67%-69%

1-Monochloro-1,1-difluoroethane: 15%-17%

Refrigerant of the present invention is characterized in that above-mentioned refrigerant also contains isobutane, and its component content (mass percentage) is respectively:

Chlorodifluoromethane: 27%-29%

1,1,1,2,3,3,3-Heptafluoropropane: 58%-60%

1-Monochloro-1,1-difluoroethane: 9%-11%

Isobutane: 2%-4%

The four component contents (mass percentages) of the above-mentioned refrigerants can be respectively:

Chlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-Heptafluoropropane: 66%-68%

1-Monochloro-1,1-difluoroethane: 14%-16%

Isobutane: 2%-3%

The preparation method of the refrigerant provided by the present invention is to physically mix the above-mentioned various components according to their corresponding proportions in a liquid state.

Among the above components, chlorodifluoromethane (HCFC-22) has a molecular formula of CHClF ₂ , a molar mass of 86.47, a normal boiling point of -40.81°C, a critical temperature of 96.15°C and a critical pressure of 4.99MPa.

1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea), its molecular formula is CF ₃ CHFCF ₃ , its molar mass is 170.03, its normal boiling point is -15.61°C, its critical temperature is 101.74°C, and its critical pressure is 2.929 MPa.

Isobutane (HC-600a) has a molecular formula of CH(CH ₃ ) ₂ CH ₃ , a molar mass of 58.12, a normal boiling point of -11.61°C, a critical temperature of 134.7°C and a critical pressure of 3.64MPa.

1-chloro-1,1-difluoroethane (HCFC-142b), its molecular formula is CH ₃ CClF ₂ , its molar mass is 100.49, its normal boiling point is -9.0°C, its critical temperature is 137.1°C, and its critical pressure is 4.12MPa .

The present invention has the following advantages and beneficial effects:

a.Environmental performance

The ozone layer destruction potential (ODP) of this refrigerant is very small, close to zero, and its greenhouse effect coefficient (GWP) is much smaller than R12. It can be seen that the present invention fully complies with the environmental protection requirements of protecting the ozone layer and reducing the greenhouse effect, and Table 2 shows the environmental performance comparison with Freon-12.

Table 2 Environmental performance comparison Refrigerant Freon-12 this invention ODP 1.0 0.021 GWP (100 years) 8500 2044

b. Thermal parameters:

Under standard design conditions, the pressure value of the refrigerant in the evaporator and condenser, and the pressure ratio of the compressor are similar to those of Freon-12, and the exhaust temperature is lower than that of Freon-12.

Table 3 Comparison of Thermal Parameters Refrigerant Freon-12 this invention Evaporating pressure (kPa) 387.1 374.7 Condensing pressure (kPa) 1345.5 1410.9 Pressure ratio 3.48 3.77 Exhaust temperature (℃) 89.2 78.9

c. Thermal performance

The thermal performance (COP, cooling capacity and volumetric cooling capacity) of this refrigerant is slightly higher than Freon-12, see Table 4. This shows that this refrigerant can directly use Freon-12 compressors without modification.

Table 4 Thermal performance comparison Refrigerant Freon-12 this invention COP 1.0 1.01 Cooling capacity 1.0 1.03 Volume cooling capacity 1.0 1.01

In summary, the present invention not only has thermal performance close to that of Freon-12, basically does not destroy the ozone layer, can reduce the influence of the greenhouse effect, and meets environmental protection requirements; it is also non-toxic, non-flammable, and can be directly charged. The main components do not need to be changed, and the production line does not need to be modified; the performance is slightly better than Freon-12, and it can be used as a substitute refrigerant for Freon-12 in existing centrifugal chillers.

Detailed ways

The refrigerant of the present invention is characterized in that it is composed of chlorodifluoromethane (HCFC-22), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) and 1-chloro-1 , 1-Difluoroethane (HCFC-142b) is composed of three substances, and isobutane (HC-600a) can also be added to form a quaternary mixed refrigerant. However, due to the relatively high glide temperature of the two groups of mixtures, in order to meet the special requirements of centrifugal compressors, different types of evaporators, such as flooded or dry, require mixed refrigerants with different charging ratios.

For the centrifugal water cooling unit of the dry evaporator, the component content (mass percentage) of the ternary mixture is:

Chlorodifluoromethane: 28-30%

1,1,1,2,3,3,3-Heptafluoropropane: 60%-62%

1-Monochloro-1,1-difluoroethane: 10%-12%

For the centrifugal water-cooled unit with flooded evaporator, the component content (mass percentage) of the ternary mixture is:

Chlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-Heptafluoropropane: 67%-69%

1-Monochloro-1,1-difluoroethane: 15%-17%

For the centrifugal water-cooling unit of the dry evaporator, isobutane (HC-600a) can also be added on the basis of the aforementioned ternary mixture to have better oil solubility. Its component content (mass percentage) is:

Chlorodifluoromethane: 27%-29%

1,1,1,2,3,3,3-Heptafluoropropane: 58%-60%

1-Monochloro-1,1-difluoroethane: 9%-11%

Isobutane: 2%-4%

For centrifugal water-cooled units with flooded evaporators, isobutane (HC-600a) can also be added on the basis of the aforementioned ternary mixture to have better oil solubility. Its component content (mass percentage) is:

Chlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-Heptafluoropropane: 66%-68%

1-Monochloro-1,1-difluoroethane: 14%-16%

Isobutane: 2%-3%

In order to help the understanding of the invention and its advantages, several specific examples are listed below.

Example:

Example 1: 28% HCFC-22, 61% HFC-227ea and 11% HFC-142b were physically mixed in the liquid phase.

Example 2: 15% HCFC-22, 68% HFC-227ea and 17% HFC-142b were physically mixed in the liquid phase.

Example 3: 28% HCFC-22, 60% HFC-227ea, 3% HC-600a and 9% HFC-142b were physically mixed in the liquid phase.

Example 4: 15% HCFC-22, 67% HFC-227ea, 2.5% HC-600a and 15.5% HFC-142b were physically mixed in the liquid phase.

Under the standard design conditions of the centrifugal chiller, the thermal properties of the refrigerants in the above examples are listed in Table 1.

Table 1 embodiment thermal performance Example example 1 Example 2 Example 3 Example 4 CFC-12 Evaporating pressurekPa 363.6 368.5 374.7 376.5 387.1 Condensing pressurekPa 1384.1 1398.9 1410.9 1415.1 1345.5 Pressure ratio 3.81 3.80 3.77 3.76 3.48 Exhaust temperature °C 79.4 80.0 78.9 79.5 89.2 COP ^* 1.01 1.02 1.01 1.01 1.0 Cooling ^* 1.02 1.03 1.03 1.04 1.0 Volume cooling capacity ^* 1.0 1.01 1.01 1.01 1.0 ODP 0.023 0.021 0.021 0.019 1.0 GWP 2176 2322 2044 2198 8500

Remarks: ^* indicates the corresponding ratio with CFC-12.

Claims (3)

1. the alternative refrigerant of a F-12 centrifugal refrigerating machines, it is characterized in that: this refrigeration agent contains monochlorodifluoromethane, 1,1,1,2,3,3,3-heptafluoro-propane and 1-one chloro-1, three kinds of materials of 1-C2H4F2 C2H4F2, its mass percentage content is respectively:

Monochlorodifluoromethane: 28%-30%

1,1,1,2,3,3,3-heptafluoro-propane: 60%-62%

1-one chloro-1,1-C2H4F2 C2H4F2: 10%-12%.

2. the alternative refrigerant of a F-12 centrifugal refrigerating machines, it is characterized in that: this refrigeration agent contains monochlorodifluoromethane, 1,1,1,2,3,3,3-heptafluoro-propane and 1-one chloro-1, three kinds of materials of 1-C2H4F2 C2H4F2, its mass percentage content is respectively:

Monochlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-heptafluoro-propane: 67%-69%

1-one chloro-1,1-C2H4F2 C2H4F2: 15%-17%.

3. the alternative refrigerant of a F-12 centrifugal refrigerating machines, it is characterized in that: this refrigeration agent contains monochlorodifluoromethane, 1,1,1,2,3,3,3-heptafluoro-propane, 1-one chloro-1, four kinds of materials of 1-C2H4F2 C2H4F2 and Trimethylmethane, its mass percentage content is respectively:

Monochlorodifluoromethane: 14%-16%

1,1,1,2,3,3,3-heptafluoro-propane: 67%-68%

1-one chloro-1,1-C2H4F2 C2H4F2: 14%-16%

Trimethylmethane: 2%-3%