A propane-rich mixed working fluid and its application

Abstract

The present application discloses a propane-rich mixed working fluid and its application. By screening a suitable working fluid with a standard boiling point lower than R290 and meeting environmental protection requirements, and mixing it with R290 in a certain proportion, a mixed working fluid with exhaust superheat, suction pressure, performance coefficient and heating capacity per unit volume higher than pure R290 is obtained, which solves the problems of insufficient oil viscosity and suction vacuum that may occur when a heat pump using propane as a working fluid is running at low ambient temperature, and not only makes up for the defects of pure R290 heat pump running under low ambient temperature conditions, but also improves the system's energy efficiency and can reduce the operating cost of the heat pump system. At the same time, the mixed working fluid also meets the current environmental protection requirements of protecting the ozone layer and reducing the greenhouse effect, and has broad application prospects.

Description

Technical Field

[0001] The present application relates to a mixed working fluid, and in particular to a propane-rich mixed working fluid and application thereof. Background Art

[0002] As environmental issues become increasingly prominent, working fluids, as one of the core components of refrigeration and heating devices, are subject to increasingly stringent restrictions. In order to solve the problem of ozone depletion, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) (such as R12 and R22) have been banned one after another; in order to mitigate the greenhouse effect, countries around the world have set a timeline for reducing hydrofluorocarbons (HFCs) (such as R410A), which has led to an increasingly narrow choice of working fluids.

[0003] For heat pumps, R410A and R32 are still the main working fluids used. R32 is not suitable for producing high-temperature hot water above 65°C due to its lower critical temperature (78°C) and higher critical pressure (5.8MPa). Especially when the ambient temperature is low, the outlet water temperature will be further reduced, requiring more electric heating, which weakens the environmental protection and economy of the heat pump. R410A has entered the countdown of use due to its higher GWP, and its lower critical temperature than R32 determines that it is not suitable for producing high-temperature hot water in heat pumps.

[0004] Propane (R290) has an ozone depletion potential (ODP) of 0, an extremely low global warming potential (GWP), a high critical temperature (97°C), a low critical pressure (4.3MPa), and good thermal cycle performance. It can easily achieve a water outlet temperature of over 75°C, and even at an ambient temperature of -25°C, it can achieve a water outlet temperature of 65°C. Therefore, it is regarded as an alternative working fluid for future heat pumps and has received attention from heat pump manufacturers around the world. Currently, R290 heat pump products are on the market.

[0005] However, R290 also has some defects, which lead to many difficulties in application. For example, @R290 is classified as A3 by ASHRAE, which is highly flammable, but it can be designed as an integral unit.

[0006] The working fluid does not enter the house, and the heat exchange with the room and the water tank heating are achieved by producing hot and cold water.

[0007] Avoid the risk;

[0008] The exhaust gas superheat of R290 is low, which makes it very easy for the exhaust gas to be superheated during the startup phase under low ambient temperature conditions.

[0009] Condensation inside the compressor causes the lubricating oil to be diluted, which in turn causes the problem of insufficient oil viscosity, affecting the compression

[0010] The operating life of the compressor;

[0011] R290 has a high standard boiling point, which results in the suction pressure being close to atmospheric pressure at low ambient temperature.

[0012] When the temperature is close to -25℃ or even lower, the R290 heat pump will be at risk of vacuuming.

[0013] Since mixed working fluids have complementary physical properties, their respective defects can be overcome to a certain extent through the combination of working fluids. In the prior art, the mixed working fluid is mainly based on difluoromethane (R32) and / or carbon dioxide (R744), to which a certain amount of other working fluids (such as R290, R13I1) are added, and its application objects are mainly refrigeration and air-conditioning systems. Since the operating range of the heat pump is significantly different from that of the refrigeration and air-conditioning system, if the working fluid is directly transferred and used, it will cause many problems such as energy efficiency attenuation or even inability to operate. Therefore, it is necessary to develop a mixed working fluid for the heat pump that matches its operating range.

[0014] Patent CN1087107A discloses a mixture of R32 and R290, wherein the mass fraction of R32 is 67-90%, which is used as a refrigerant, expansion agent, etc. Patent CN101781548A discloses a mixed refrigerant containing two components, R32 and R290, wherein the mass fraction of R32 is 45-90%, which is used to replace R410A. In the above two patents, the proportion of R32 in the mixed working fluid is relatively high. Under the heat pump working conditions of ambient temperature -25℃ and outlet water temperature 65℃, when the mass fraction of R32 exceeds 50%, there will be a risk of compressor exhaust temperature exceeding the limit, which requires the introduction of a supplementary air compressor and the use of more complex control to avoid it. Therefore, it is not a suitable working fluid for heat pumps.

[0015] Patent CN111662685A discloses a cooling device and a mixed refrigerant, wherein the mass fraction of R744 in the refrigerant mixture is 5-65%, the mass fraction of R32 is as high as 68%, and the other component is trifluoroiodomethane (CF3I), fluoromethane (CH3F), ethane (C2H6), 1,1-difluoroethylene (C2H2F2), ethylene (C2H4), fluoroethylene (C2H3F), acetylene (C2H2), propane (C3H8), propylene (C3H6) and / or fluoroethane (CH2FCH3), and the mass fraction of the other component is as high as 55%, which is used for air conditioning. The patent mainly involves a ternary mixture containing R744 and R32. In the disclosed mixed working fluid ratio, the ratio of R744 to R32 is relatively high, which will also lead to excessively high exhaust temperature of the compressor under low ambient temperature and high water temperature conditions, affecting the normal operation of the heat pump, which means that the mixed working fluid is not suitable for use in the heat pump.

[0016] The above information disclosed in the background technology is only used to increase the understanding of the background technology of the present application, and therefore, it may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0017] This application aims to solve the problem that heat pumps using pure R290 as the working fluid in the prior art condense in the compressor due to insufficient exhaust superheat under low ambient temperature conditions, affecting the operating life of the compressor, and overcome the risk of vacuuming due to the suction pressure close to atmospheric pressure, and propose an environmentally friendly mixed working fluid rich in R290 suitable for heat pumps with an ambient temperature above -30°C and a water outlet temperature above 35°C. The mixed working fluid has an ODP of 0 and a very low GWP. Compared with pure R290, it has a higher exhaust superheat and suction pressure, and the performance coefficient and heating capacity per unit volume are significantly improved.

[0018] Specifically, this application adopts the following technical solutions:

[0019] A mixed working fluid comprises a first component with a mass concentration of not less than 70% and a second component with a remaining mass concentration, wherein the first component is propane (R290) and the second component is a combination of at least two of trifluoroethylene (R1123), fluoromethane (R41), ethane (R170), ethylene (R1150), and difluoromethane (R32).

[0020] A mixed working fluid comprises a first component with a mass concentration of not less than 70% and a second component with a remaining mass concentration, wherein the first component is propane (R290) and the second component is any one of trifluoroethylene (R1123) and fluoromethane (R41).

[0021] In some embodiments of the present application, a first component having a mass concentration of not less than 80% and a second component having a remaining mass concentration are included, wherein the first component is propane (R290) and the second component is any one of trifluoroethylene (R1123) and fluoromethane (R41).

[0022] In some embodiments of the present application, a first component having a mass concentration of not less than 90% and a second component having a remaining mass concentration are included, wherein the first component is propane (R290) and the second component is any one of trifluoroethylene (R1123) and fluoromethane (R41).

[0023] The mixed working fluid is used in a heat pump system. Preferably, the heat pump is used in an environment of -30°C or above, with a heating temperature of 35°C or above.

[0024] The present application also discloses an application of a mixed working fluid, comprising a first component with a mass concentration of not less than 70% and a second component with a remaining mass concentration, wherein the first component is propane (R290), and the second component is any one of ethane (R170), ethylene (R1150), and difluoromethane (R32); the mixed working fluid is applied in a heat pump system. Preferably, the heat pump is applied in an environment of -30°C or above, and the heating temperature is 35°C or above.

[0025] By screening suitable working fluids with a standard boiling point lower than R290 and meeting environmental protection requirements, and mixing them with R290 in a certain proportion, we can obtain a mixed working fluid with higher exhaust superheat, suction pressure, performance coefficient and heating capacity per unit volume than pure R290. This can not only make up for the defects of pure R290 heat pumps operating under low ambient temperature conditions, but also improve the system's capacity and energy efficiency.

[0026] Compared with the existing R290 working fluid, this application has the following beneficial effects:

[0027] (1) Similar environmental performance: The mixed working fluid proposed in this application has an ODP of 0 and a GWP of less than 203.

[0028] Some are less than 30, which is in line with the current environmental protection requirements of protecting the ozone layer and reducing the greenhouse effect.

[0029] (2) Higher exhaust superheat and suction pressure: Under the conditions of ambient temperature of -25°C and outlet water temperature of 65°C, the exhaust superheat of the mixed working fluid proposed in this application is up to 25°C higher than that of pure R290, which can effectively solve the problem of insufficient superheat of the compressor oil pool; the suction pressure is increased by up to 87kPa, and the difference with atmospheric pressure increases from 26kPa of pure R290 to 103kPa, effectively avoiding the risk of system vacuuming. Under other low ambient temperature conditions, the exhaust superheat and suction pressure of the mixed working fluid are also significantly higher than that of pure R290, which greatly increases the reliability of the low ambient temperature operation of the heat pump.

[0030] (3) Better thermal performance and economy: The mixed working fluid proposed in this application has a higher performance coefficient and heating capacity per unit volume, which can reduce operating costs and obtain more heat at the same compressor frequency, thereby improving the problem of insufficient heating capacity when the ambient temperature is low. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present application without departing from the spirit and scope of the technical scheme of the present application, and all should be included in the protection scope of the present application.

[0032] 1. Explanation of the environmental friendliness of the mixed working fluid described in this application is equivalent to R290 (Beneficial Effect 1)

[0033] The standard boiling point, critical temperature, critical pressure, ODP, GWP and other physical properties of each component of the mixed working fluid involved in this application are shown in Table 1. It can be found that the ODP of the mixed working fluid proposed in this application is 0; through simple calculation, it can be obtained that according to the ratio described in this application, the GWP of the mixed working fluid containing R32 is <203, and the GWP of the mixed working fluid without R32 is <30, which meets the current environmental protection requirements for protecting the ozone layer and reducing the greenhouse effect.

[0034] Table 1 Physical properties of each component of the mixed working fluid involved in this application

[0035]

[0036] 2. Explain that the mixed working fluid described in this application has higher exhaust superheat, suction pressure, better thermal performance and economy than R290 (Beneficial Effects 2 and 3)

[0037] The following will compare the cycle parameters and performance of the mixed working fluid and R290 in the operating range of ambient temperature -30 ~ 0℃ and outlet water temperature 55 ~ 75℃, and further illustrate the superiority of the mixed working fluid.

[0038] The actual operating range of the R290 heat pump within the above operating range is shown in Table 2. It can be seen that the R290 heat pump cannot operate under the conditions of ambient temperature -30℃ (A-30) and ambient temperature -25℃, water outlet temperature 75℃ (A-25W75). Therefore, for comparison, the R290 heat pump cycle only calculates the remaining 8 operating points, as shown in Table 3 (Comparative Examples 1 to 8). The calculation results include operating pressure, pressure ratio, logarithmic mean temperature difference (LMTD) of the heat exchanger, COP, heating capacity per unit volume (q zv ) and exhaust superheat (Tdsh). In the calculation process, the adiabatic efficiency of the compressor is 0.8, the condenser resistance is 30kPa, the evaporator resistance is 10kPa, the pinch point temperature difference of the two heat exchangers is 5℃, and the inlet / outlet water temperatures on the water side are 47 / 55℃, 55 / 65℃ and 65 / 75℃ respectively.

[0039] Tables 4 to 8 (Examples 1 to 111) show the cycle parameters, performance and improvement relative to R290 of the binary mixed working fluid rich in R290 described in this application under the conditions of ambient temperature -30 to 0°C and outlet water temperature 55 to 75°C. For some binary mixed working fluids, after the suction pressure, the operating range can be expanded to the A-30W55 condition, such as Examples 25, 34, 43, 52, 61, 70, and 79, so there is no relative value of improvement. During the calculation process, the compressor adiabatic efficiency and the resistance of the two heat exchangers are the same as above, and the heat exchanger temperature difference is kept consistent with the logarithmic mean temperature difference obtained in the comparative calculation under the same working conditions to ensure that the heat exchanger area is equivalent, making the results more convincing.

[0040] For multi-component mixed working fluids (ternary and above), the changes in the two dimensions of components and concentration will result in an inexhaustible combination of mixed working fluids. Therefore, some combinations are selected for calculation to illustrate the superiority of multi-component mixed working fluids. Mixed working fluid combinations and embodiments (112-126) are shown in Tables 9 and 10, respectively. In the calculation, the selection of the compressor adiabatic efficiency, the resistance of the two heat exchangers, and the heat exchange temperature difference is consistent with the above calculation.

[0041] Table 2 The operating range of R290 heat pump under ambient temperature of -30~0℃ and outlet water temperature of 55~75℃

[0042]

[0043] Table 3 R290 heat pump cycle parameters and performance at ambient temperature -30~0℃ and outlet water temperature 55~75℃

[0044]

[0045]

[0046] Table 4 Heat pump cycle parameters, performance and improvement at ambient temperature -30~0℃ and outlet water temperature 55~75℃ (R290+R1123)

[0047]

[0048]

[0049] Table 5 Heat pump cycle parameters, performance and improvement at ambient temperature -30~0℃ and outlet water temperature 55~75℃ (R290+R41)

[0050]

[0051] Table 6 Heat pump cycle parameters, performance and improvement at ambient temperature -30~0℃ and outlet water temperature 55~75℃ (R290+R170)

[0052]

[0053] Table 7 Heat pump cycle parameters, performance and improvement at ambient temperature -30~0℃ and outlet water temperature 55~75℃ (R290+R1150)

[0054]

[0055]

[0056] Table 8 Heat pump cycle parameters, performance and improvement at ambient temperature -30~0℃ and outlet water temperature 55~75℃ (R290+R32)

[0057]

[0058]

[0059] Table 9 Examples of multi-component mixed working fluid combinations (by mass fraction)

[0060]

[0061] Table 10 Parameters, performance and improvement of heat pump cycle with multi-component mixed working fluid (I~V)

[0062]

[0063] 1. Exhaust superheat and suction pressure increase

[0064] It can be seen from the ΔTdsh column in Tables 4 to 8 and 10 that the difference between the exhaust superheat of the embodiment and the comparative example is always positive. Under different working conditions, different mixed working fluid components and proportions, the exhaust superheat can be increased by 2 to 25°C, indicating that the mixed working fluid can effectively increase the exhaust superheat, thereby increasing the superheat of the compressor oil pool and solving the problem of low oil viscosity when starting under low ambient temperature conditions.

[0065] By comparing the suction pressures in Tables 4 to 8, 10 and Table 3, it can be seen that the suction pressure of the embodiment under the same working conditions is always higher than that of the comparative example. Under the working conditions of low ambient temperature and high water temperature (such as A-25W65), the suction pressure is increased by 87 kPa at most, and the difference with the atmospheric pressure increases from 26 kPa of pure R290 to 103 kPa, which can effectively avoid system vacuuming and improve the reliability of system operation.

[0066] 2. Increase in performance coefficient and heating capacity per unit volume

[0067] From the Δq in Tables 4 to 8 and 10 zv It can be seen from the table that the heating capacity per unit volume of the embodiment is always higher than that of the comparative example. Under different working conditions, different mixed working fluid components and proportions, q zvIt can be increased by 5.23% to 75.50%, and more heat can be generated at the same compressor frequency, effectively improving the problem of insufficient heating capacity of the current R290 heat pump under low ambient temperature conditions.

[0068] It can be seen from the ΔCOP columns of Tables 4 to 8 and 10 that the COP of most of the embodiments is higher than that of the comparative examples. In Examples 55, 58, 71-78, 116, and 117, the COP is attenuated by 0.03% to 4.73% compared with the comparative examples, but q zv The increase is 31.97% to 59.81%, which is obviously more beneficial than harmful for ensuring the heating capacity under low ambient temperature; in other embodiments, except q zv In addition to the improvement, COP is also improved by 0.02% to 7.57%, which means that the low-temperature heating capacity is improved without losing energy efficiency.

[0069] In summary, the environmental friendliness of the mixed working fluid proposed in this application is similar to that of propane, with an ODP of 0 and a very low GWP, which meets the current environmental protection requirements of protecting the ozone layer and reducing the greenhouse effect; it can effectively improve the exhaust superheat and suction pressure of R290, solve the problems of insufficient oil viscosity and suction vacuum that may occur under low ambient temperature conditions, and improve the reliability and heating capacity of the heat pump's low ambient temperature operation; at the same time, compared with propane, it has better energy efficiency, can reduce the operating cost of the heat pump system, and has broad application prospects.

[0070] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A mixed working fluid, characterized in that: The invention relates to a first component having a mass concentration of not less than 70% and a second component having a remaining mass concentration, wherein the first component is propane (R290), and the second component is a combination of at least two of trifluoroethylene (R1123), fluoromethane (R41), ethane (R170), ethylene (R1150), and difluoromethane (R32).

2. The mixed working medium according to claim 1, characterized in that: Contains a first component with a mass concentration of not less than 80% or not less than 90% and a second component with a remaining mass concentration.

3. A mixed working fluid, characterized in that: The invention comprises a first component with a mass concentration of not less than 70% and a second component with a remaining mass concentration, wherein the first component is propane (R290) and the second component is one of trifluoroethylene (R1123) and fluoromethane (R41) or a combination thereof.

4. The mixed working medium according to claim 3, characterized in that: The method comprises a first component having a mass concentration of not less than 80% and a second component having a remaining mass concentration.

5. An application of a mixed working fluid, characterized in that: The mixed working fluid is the mixed working fluid according to any one of claims 1 to 4, and the mixed working fluid is applied in a heat pump system.

6. The use of the mixed working medium according to claim 5, characterized in that: The heating temperature of the heat pump system is 35°C or above and / or the ambient temperature of the heat pump system is not lower than -30°C.

7. An application of a mixed working fluid, characterized in that: The invention relates to a mixed working fluid comprising a first component with a mass concentration of not less than 70% and a second component with a remaining mass concentration, wherein the first component is propane (R290) and the second component is one or more of ethane (R170), ethylene (R1150) and difluoromethane (R32); the mixed working fluid is used in a heat pump system.

8. The use of a mixed working medium according to claim 7, characterized in that: The method comprises a first component having a mass concentration of not less than 80% and a second component having a remaining mass concentration.

9. The use of a mixed working medium according to claim 7, characterized in that: The method comprises a first component having a mass concentration of not less than 90% and a second component having a remaining mass concentration.

10. The use of the mixed working fluid according to any one of claims 7 to 9, characterized in that: The heating temperature of the heat pump system is 35°C or above and / or the ambient temperature of the heat pump system is not lower than -30°C.

Images