JP6765538B2 - Refrigeration equipment and operation method of refrigeration equipment - Google Patents

Description

The present invention relates to a refrigerating apparatus, and more particularly to a refrigerating apparatus to which a non-azeotropic mixed refrigerant is applied and a method of operating the refrigerating apparatus.

Conventionally, there is known a freezing device having a refrigerating cycle in which an evaporator, a compressor, a condenser, and a depressurizing device are connected by a pipeline through which a refrigerant circulates.

Further, in a refrigerating device such as an air conditioner or a refrigerator, the heat exchanger acting as an evaporator is opposed to the heat exchange air and the refrigerant by reversing the flow direction of the heat exchange air and the flow direction of the refrigerant. Is known to have a counterflow to reduce heat exchange loss and improve performance (see, for example, Patent Document 1).

On the other hand, as the refrigerant used in the refrigerating apparatus, a non-azeotropic mixed refrigerant in which a plurality of types of refrigerants are mixed may be used (see, for example, Patent Document 2). Countercurrent exchange can also be achieved for the evaporator of a refrigerating device that uses a non-azeotropic mixed refrigerant. In particular, in the non-azeotropic mixed refrigerant, the refrigerant temperature changes due to a phase change under the same pressure. That is, since the non-azeotropic mixed refrigerant has a temperature gradient in the evaporation process, for example, in the case of an evaporator, the temperature on the upstream side is lower than that on the downstream side in the evaporation process. Therefore, the temperature difference between the refrigerant and the heat source medium such as air or water can be made smaller, and the coefficient of performance (COP) is improved.

JP-A-2015-141090 JP-A-7-208822

However, in low temperature equipment where the saturation temperature is below freezing, frost will occur on the evaporator. If a non-azeotropic mixed refrigerant is used in the evaporation process of a low-temperature device in which frost formation occurs, the frost formation of the evaporator is biased. That is, on the inlet side of the evaporator having a low temperature of the non-co-boiling mixed refrigerant having a temperature gradient such that the refrigerant temperature changes due to the phase change under the same pressure as described above, cooling of the air is promoted and the amount of frost formation increases. On the outlet side of the evaporator where the temperature of the refrigerant is high, the cooling of the air does not proceed and the amount of frost formation decreases. In this way, when the frost formation is biased in the evaporator, even if the total amount of frost formation is the same as in the case where the frost formation is uniform, the space between the fins on the inlet side of the evaporator is set earlier. Frost clogs and reduces the heat exchange rate. Therefore, the effect of deterioration of the heat exchange rate due to uneven frost becomes greater than the improvement of the heat exchange rate due to countercurrent exchange between the refrigerant and the heat source medium, the evaporation pressure in the evaporator decreases, and the COP of the refrigerating device and the refrigerating device There was a problem that the refrigerating capacity of the water was reduced.

According to the present invention, in a freezing device using a non-co-boiling mixed refrigerant having a temperature gradient, the COP of the freezing device and the freezing device and the freezing device that prevent a decrease in the freezing capacity of the freezing device by preventing uneven frost formation. The purpose is to provide a driving method.

The refrigerating apparatus according to the present invention includes a refrigerating cycle in which a compressor, a condenser, a depressurizing device, and an evaporator are connected by a refrigerant pipe and a refrigerant circulates inside, and the refrigerant is a ratio of _R32 X _R32. The condition that (wt%) is 33 wt% <X _R32 <39 wt% , the ratio of _R125 X _R125 (wt%) is 27 wt% <X _R125 <33 wt%, and the ratio of _R134a X _R134a (wt %). %) Is 11 wt% <X _R134a <17 wt% and the ratio of _R1234yf X _R1234yf (wt%) is 11 wt% <X _R1234yf <17 wt% and the ratio of carbon dioxide X _CO2 (wt%) ) Is 3 wt% <X _CO2 <9 wt% , and the condition that X _R32 , X _R125 , X _R134a , X _R1234yf , and X _CO2 total X _total is 100 wt% is satisfied. or a R410A, the evaporator may fit in the temperature gradient of the isotherm of the gas-liquid two phase region of the non-azeotropic mixed refrigerant reduces along the direction of flow of the conduit pressure in the evaporation process of the refrigerant, the In order for the refrigeration cycle to correspond to both the mixed refrigerant and R410A, the number of passes of the refrigerant passing through the evaporator is freely changed, and when the refrigerant is the mixed refrigerant, the refrigerant is R410A. It is characterized in that the number of passes of the refrigerant is reduced as compared with the case of .

According to the present invention, according to the above configuration, in a freezing device using a non-co-boiling mixed refrigerant having a temperature gradient, the refrigerant temperature in the evaporator can be made substantially uniform, and the frost formation bias of the evaporator can be prevented. The purpose is to obtain a freezing device that suppresses the COP of the freezing device and suppresses the decrease in the freezing capacity.

It is the schematic which shows the whole structure of the refrigerating apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows the structure of the evaporator of the refrigerating apparatus which concerns on Embodiment 1 of this invention. The Moriel diagram of the non-azeotropic mixed refrigerant used in the refrigeration apparatus according to the first embodiment of the present invention is shown. It is a control flow diagram of the refrigerating apparatus according to Embodiment 1 of this invention. The Moriel diagram of the non-azeotropic mixed refrigerant used in the refrigeration apparatus according to the second embodiment of the present invention is shown. It is the schematic which shows the structure of the evaporator of the refrigerating apparatus which concerns on Embodiment 2 of this invention.

Embodiment 1.
FIG. 1 is a schematic view showing the overall configuration of the refrigerating apparatus 100 according to the first embodiment of the present invention. In each figure, the same parts or corresponding parts are designated by the same reference numerals. In the refrigerating device 100 of the first embodiment, as shown in FIG. 1, the compressor 1, the condenser 2, the depressurizing device 3, and the evaporator 4 are sequentially connected by a refrigerant pipe 5. The refrigerating device 100 includes a refrigerating cycle in which the refrigerant circulates in the order of the compressor 1, the condenser 2, the depressurizing device 3, the evaporator 4, and the compressor 1. The control unit 60 controls each device constituting the refrigerating device 100.

(Compressor 1)
The compressor 1 sucks in the refrigerant, compresses it into a high-temperature and high-pressure gas state, and discharges the refrigerant. The compressor 1 may be configured such that the rotation speed is controlled by, for example, an inverter circuit or the like, and the discharge amount of the refrigerant can be adjusted by controlling the rotation speed.

(Condenser 2)
In the condenser 2, the refrigerant compressed by the compressor 1 into a high-temperature and high-pressure gas state flows in, and heat exchange is performed between the refrigerant and the heat source to cool the refrigerant into a low-temperature and high-pressure liquid state. Examples of the heat source include air, water, brine, and the like. In the first embodiment, the heat source of the condenser 2 is outside air, which is outdoor air. The condenser 2 exchanges heat between the outside air and the refrigerant. Further, the first embodiment has a condenser blower 6 that blows outside air to the condenser 2 when the refrigerant is circulating in the refrigerating apparatus 100 in order to promote heat exchange of the condenser 2. The condenser blower 6 may be configured to have an adjustable air volume.

(Decompression device 3)
In the depressurizing device 3, the low-temperature and high-pressure liquid state refrigerant cooled by the condenser 2 flows in, and the refrigerant is decompressed and expanded to the low-temperature and low-pressure liquid state. The pressure reducing device 3 is composed of, for example, an electronic expansion valve, a refrigerant flow rate control means such as a temperature sensitive expansion valve, a capillary tube, or the like.

(Evaporator 4)
In the evaporator 4, a low-temperature low-pressure liquid refrigerant expanded under reduced pressure by the depressurizing device 3 flows in, exchanges heat between the refrigerant and the cooling target, absorbs the heat of the cooling target into the refrigerant, and cools the target. To cool. When the cooling object is cooled, the refrigerant evaporates and becomes a high-temperature and low-pressure gas state. In the first embodiment, the cooling target is indoor air. That is, the evaporator 4 exchanges heat between the indoor air and the refrigerant. Further, in the first embodiment, in order to promote heat exchange between the indoor air and the refrigerant in the evaporator 4, the evaporator that blows the indoor air to the evaporator 4 when the refrigerant is circulating in the refrigerating apparatus 100. It has a blower 7. The evaporator blower 7 may be configured to have an adjustable air volume.

The specific configuration of the evaporator 4 will be described with reference to FIG. The evaporator 4 is a plate fin tube heat exchanger composed of a plurality of heat transfer tubes 41, a plurality of fins 42, a refrigerant distributor 43, and a header 44. In FIG. 2, the number of heat transfer tubes 41 is 5, and the number of fins 42 is 28. However, the number and number of these are examples, and the present invention is not limited to this number and number.

FIG. 2 is a schematic view showing the configuration of the evaporator 4 of the refrigerating device 100 according to the first embodiment of the present invention. FIG. 2 schematically shows the evaporator 4. Here, the flow of the refrigerant in the evaporator 4 will be described with reference to FIG. First, the low-temperature low-pressure liquid-state refrigerant expanded under reduced pressure by the decompression device 3 flows in from the inflow port of the refrigerant distributor 43. The refrigerant flowing in from the inlet of the refrigerant distributor 43 is distributed in a plurality of ways at the outlet of the refrigerant distributor 43, and flows from each outlet of the refrigerant distributor 43 to the heat transfer tube 41. The refrigerant that has flowed into the heat transfer tube 41 flows along the axial direction of the heat transfer tube 41. The surfaces of the heat transfer tube 41 and the fin 42 are in contact with the indoor air to be cooled blown by the blower 7 provided in the evaporator 4. The indoor air blown toward the fins 42 of the evaporator 4 flows in a direction opposite to the flow of the refrigerant flowing inside the evaporator 4. The refrigerant flowing inside the heat transfer tube 41 exchanges heat with the indoor air in contact with the heat transfer tube 41 and the fins 42, and absorbs the heat of the indoor air. The refrigerant that has exchanged heat with the indoor air through the heat transfer tube 41 flows in from the inlet of the header 44, merges at the header 44, and flows to the compressor 1 from the outlet of the header 44.

FIG. 3 shows a Moriel diagram of a non-azeotropic mixed refrigerant used in the refrigeration apparatus 100 according to the first embodiment of the present invention. The non-co-boiling mixed refrigerant is formed by mixing two or more kinds of refrigerants having different boiling points, and in a gas-liquid two-phase state, the pressure saturation temperature of the refrigerant changes according to the degree of dryness even under a constant pressure. That is, when the refrigerant in the evaporator 4 is evaporated along the constant pressure line shown by the dotted line A in FIG. 3, the temperature at the inlet of the evaporator 4 becomes low and the temperature at the outlet becomes high. Therefore, as shown by the dotted line B in FIG. 3, the temperature of the non-azeotropic mixed refrigerant flowing through the evaporator 4 can be made uniform by continuously lowering the pressure inside the evaporator 4 with a predetermined gradient. .. Then, by keeping the inlet temperature and the outlet temperature of the evaporator 4 uniform, it is possible to suppress the unevenness of frost formation generated in the evaporator 4.

When the pressure inside the evaporator 4 is gradually lowered, a pressure difference is generated between the inlet and the outlet of the evaporator 4. The relationship between the pressure of the refrigerant flowing inside the evaporator 4 and the saturation temperature is uniquely determined according to the composition of the refrigerant. Therefore, the pressure difference between the inlet and the outlet of the evaporator 4 when the temperature is made uniform at the inlet and the outlet of the evaporator 4 is uniquely determined according to the composition of the refrigerant. Therefore, in the actual refrigerating apparatus 100, the pressure difference of the refrigerant between the inlet and the outlet of the evaporator 4 is adjusted to the temperature of the refrigerant flowing through the evaporator 4, and the refrigerant at the inlet and the outlet of the evaporator 4 is made uniform. By making the pressure difference the same, it is possible to suppress the uneven frost formation of the evaporator 4.

As a means for continuously lowering the pressure of the refrigerant inside the evaporator 4 with a predetermined gradient, there is a means for stepwise changing the inner diameter of the heat transfer tube 41 through which the refrigerant passes. The heat transfer tube 41 constituting the evaporator 4 is usually a tube having a uniform inner diameter, but for example, by gradually reducing the cross-sectional area of the heat transfer tube 41 from the inlet to the outlet of the evaporator 4, the refrigerant flowing inside is gradually reduced. The pressure can be reduced. Alternatively, for example, the cross-sectional area of the heat transfer tube 41 may be gradually reduced from the inlet to the outlet of the evaporator 4.

Alternatively, a resistor may be provided in the conduit of the heat transfer tube 41, and the pressure of the refrigerant flowing inside may be reduced by the conduit resistance. For example, it is possible to increase the pipeline resistance and increase the pressure loss of the refrigerant flowing inside the heat transfer tube 41 by providing unevenness on the inner wall surface of the heat transfer tube 41.

Further, it is possible to take measures such as lengthening the heat transfer tube 41 to increase the pressure loss due to the line resistance and increasing the pressure difference between the inlet and the outlet of the evaporator 4. The above means may be appropriately selected according to the temperature gradient of the non-azeotropic mixed refrigerant to be applied.

Further, by controlling the flow velocity of the refrigerant passing through the evaporator 4 by providing a flow rate adjusting valve at the inlet of the evaporator 4 or controlling the operating rotation speed of the compressor 1, the operating state and the applied non-azeotropic valve can be controlled. It is also possible to continuously reduce the pressure inside the evaporator 4 with a predetermined gradient regardless of the type of the boiling mixed refrigerant.

From the above, when a refrigerant having a temperature gradient is used in the evaporation process, the temperature of the refrigerant in the evaporator 4 is made substantially the same by configuring the piping pressure loss in the evaporator 4 to be substantially the same as the temperature gradient of the refrigerant. Can be uniform. This makes it possible to prevent the performance of the refrigerating apparatus 100 from deteriorating due to frost formation biased toward the inlet side where the refrigerant of the evaporator 4 flows.

(Control of refrigeration apparatus 100)
FIG. 4 is a control flow chart of the refrigerating apparatus 100 according to the first embodiment of the present invention. The refrigerating device 100 is used for a plurality of applications such as a unit cooler and a showcase. The broken line portion shown in FIG. 1 is a cooler 50, and the cooler 50 corresponds to a unit cooler or a showcase. The portion other than the broken line portion shown in FIG. 1 is a so-called heat source machine. In particular, when the cooler 50 cannot be directly controlled by the control unit 60, the control unit 60 acquires the pressure, temperature, and operating conditions of each part of the heat source machine to control the operation of the refrigerating device 100.

(Step i)
In step i, the refrigerant circulation amount Gr that circulates inside the refrigerating apparatus 100 is calculated. First, the suction pressure Ps of the compressor 1 is detected by the pressure sensor 20 provided in the pipe on the suction side of the compressor 1. Further, the suction temperature Th of the compressor 1 is detected by the temperature sensor 30 provided in the piping on the suction side of the compressor 1. The refrigerant circulation amount Gr is calculated by the following formula.
Gr = F x Vst x ηv x ρs x 3600 x ^10-6
Here, F [Hz]: the operating frequency of the compressor 1, Vst [cc]: the amount of displacement of the compressor 1, ηv: the volumetric efficiency of the compressor 1, ρs [kg / m ³ ]: the intake gas of the compressor 1. Density. F can be acquired as the operating frequency of the compressor from the operating data of the refrigerating apparatus 100. Vst and ηv are values unique to the compressor 1, and may be stored in the control unit 60 in advance. ρs takes a value unique to each refrigerant type and can be obtained from the suction pressure Ps and the suction temperature Th. Step i is called a refrigerant circulation amount calculation step.

(Step ii)
In step ii, the pressure loss ΔP between the inlet and outlet of the evaporator 4 is calculated from the refrigerant circulation amount Gr obtained in step i. ΔP is calculated by the following formula.
ΔP = α × f × (l / d) × (ρu ² / 2g)
Here, l [m]: pipe length, d [m]: pipe diameter, ρ [kg / m ³ ]: liquid density, u [m / s]: refrigerant flow velocity, f: friction loss coefficient, α: correction coefficient ,. Note that α, f, l, d, and g are fixed values. From the equation, it can be seen that the pressure loss ΔP increases as the refrigerant flow velocity u and the refrigerant density ρ increase. The refrigerant flow velocity u is obtained from the refrigerant circulation amount Gr. For the pressure loss ΔP, the value of ΔP obtained from the relationship between the refrigerant density ρ and the refrigerant circulation amount Gr may be stored in the control unit 60 in advance. The relationship between the pressure loss ΔP, the refrigerant density ρ, and the refrigerant circulation amount Gr may be stored in the control device in advance as a look-up table. Step ii is called a pressure loss detection step of the evaporator 4.

(Step iii)
The inlet pressure Pein of the evaporator 4 is calculated. The inlet pressure Pein is calculated from Pein = Ps + ΔP. In addition, steps i to iii are collectively referred to as a detection step for detecting the pressure in the pipeline at the inlet portion of the evaporator and the outlet portion of the evaporator.

(Step iv)
The saturation temperature TEIN at the inlet of the evaporator 4 is converted from Pein. Further, the saturation temperature Teout at the outlet of the evaporator 4 is converted from the suction pressure Ps. The conversion is obtained from the saturation pressure conversion table specific to the refrigerant type. The step iv is called a temperature gradient detection step of obtaining a temperature gradient between the inlet of the evaporator 4 and the outlet of the evaporator 4.

(Step v)
The compressor operating frequency F is controlled so that the difference ΔTe = Teout-Tein between the saturation temperature at the inlet of the evaporator and the saturation temperature at the outlet of the evaporator becomes 0, and the refrigerant circulation amount Gr is changed. For example, when ΔTe> 0, the compressor operating frequency F is increased, and when ΔTe ≦ 0, the compressor operating frequency F is decreased. As ΔTe approaches 0, the pressure loss becomes parallel to the temperature gradient. The step v is called a flow velocity changing step in which the operating frequency F of the compressor 1 is changed and the flow velocity u of the refrigerant flowing through the refrigeration cycle is changed. Further, step iv and step v are collectively referred to as a pressure adjustment step. In step v, instead of changing the operating frequency F of the compressor 1, the opening degree of the flow rate adjusting valve installed on the inlet side of the evaporator 4 is changed to change the flow velocity u of the refrigerant flowing through the refrigeration cycle. Is also good. The flow rate adjusting valve may be the pressure reducing device 3. This control is performed when the control unit 60 can control the cooler 50.

(1) According to the refrigerating device 100 according to the first embodiment, the compressor 1, the condenser 2, the depressurizing device 3, and the evaporator 4 are connected by a refrigerant pipe 5, and the refrigerant circulates inside. Have a cycle. The refrigerant is a non-co-boiling mixed refrigerant in which a plurality of types are mixed, and the evaporator 4 adjusts the temperature gradient of the isotherm of the gas-liquid two-phase region of the non-co-boiling mixed refrigerant to adjust the pressure in the conduit in the evaporation process to the refrigerant. It is characterized by lowering along the flow direction of.
With this configuration, the refrigerating apparatus 100 can suppress the temperature difference of the refrigerant between the inlet side and the outlet side of the evaporator 4. Therefore, since the amount of frost formation is averaged on the inlet side and the outlet side of the evaporator 4, it is possible to prevent deterioration of the heat exchange performance of the evaporator 4 due to uneven frost formation.

(2) According to the refrigerating apparatus 100 according to the first embodiment, the cross-sectional area of the heat transfer tube 41 of the evaporator 4 decreases along the direction in which the refrigerant flows.
(3) According to the refrigerating apparatus 100 according to the first embodiment, the heat transfer tube 41 of the evaporator 4 is provided with a resistance means for resisting the flow of the refrigerant in the pipeline.
(4) According to the refrigerating apparatus 100 according to the first embodiment, the pressure in the pipeline in the evaporation process is reduced by controlling the flow velocity of the refrigerant passing through the evaporator 4.
With this configuration, the refrigerating apparatus 100 can suppress the temperature difference between the inlet and the outlet of the evaporator 4 by flowing the non-azeotropic mixed refrigerant through the evaporator 4 at a predetermined flow velocity. Further, the pressure loss given to the refrigerant flowing in the evaporator 4 can be appropriately controlled according to the refrigerant used in the refrigerating apparatus 100 by appropriately combining the means (2) to (4) above.

(5) According to the operation method of the refrigerating apparatus 100 according to the first embodiment, the refrigerant is a non-co-boiling mixed refrigerant in which a plurality of types are mixed. In the refrigerating apparatus, the inlet portion of the evaporator 4 and the evaporator 4 A detection step for detecting the pressure in the pipeline at the outlet portion and a pressure adjusting step for adjusting the difference in the pressure in the pipeline between the inlet portion and the outlet portion according to the temperature gradient of the refrigerant are provided.
By operating in this way, the refrigerating apparatus 100 can obtain the effect described in (1) above.

(6) According to the operation method of the refrigerating apparatus 100 according to the first embodiment, the flow velocity is changed by changing the flow velocity of the refrigerant flowing through the evaporator 4 to change the difference in the pressure in the pipeline between the inlet and the outlet. Have steps.
(7) According to the operation method of the refrigerating apparatus 100 according to the first embodiment, the flow velocity changing step changes the flow velocity of the refrigerant flowing through the evaporator 4 by changing the rotation speed of the compressor 1.
(8) According to the operation method of the refrigerating apparatus 100 according to the first embodiment, the flow velocity changing step changes the opening degree of the flow rate adjusting valve installed at the inlet of the evaporator to change the opening degree of the refrigerant flowing through the heat transfer tube 41. Change the flow velocity.
With this configuration, the refrigerating apparatus 100 can change the flow velocity of the refrigerant flowing through the evaporator 24 by using the compressor 1 and the flow rate adjusting valve that constitute the refrigerating cycle. Therefore, the pressure loss given to the flowing refrigerant of the evaporator 4 can be appropriately changed according to the physical properties of the non-azeotropic mixed refrigerant used in the refrigerating apparatus 100. As a result, the refrigerating apparatus 100 can obtain the effect described in (1) above.

Embodiment 2.
The refrigerating apparatus 100 according to the second embodiment is different from the refrigerating apparatus 100 according to the first embodiment in that the composition of the refrigerant circulating in the refrigerating apparatus 100 is limited. In the second embodiment, the changes from the first embodiment will be mainly described.

The non-co-boiling mixed refrigerant that circulates in the refrigerating apparatus 100 of the second embodiment is a mixed refrigerant of R32, R125, R134a, R1234yf, and carbon dioxide, and the ratio of _R32 X _R32 is 36 wt% and the ratio of R125. X _R125 is 30 wt%, R134a ratio X _R134a is 14 wt%, R1234yf ratio X _R1234yf is 14 wt%, and carbon dioxide ratio X _co2 is 6 wt%. By using such a refrigerant, the following effects can be obtained.

First, each single refrigerant has physical properties that have advantages or disadvantages, but by mixing a plurality of refrigerants, the disadvantages can be reduced and the advantages can be increased. As the physical properties of R32, since the operating pressure is high, the influence of performance deterioration due to pressure loss can be reduced, and the refrigerating capacity can be improved even when used at a low temperature such as in a supermarket showcase. As for the physical properties of R1234yf, since the global warming potential is 0, the environmental impact can be reduced. Since the physical properties of R125 and R134a are nonflammable, the flammability characteristic of R32 and R1234yf can be reduced and the safety can be enhanced. As for the physical properties of carbon dioxide, since it is a nonflammable natural refrigerant having a global warming potential of 0, it can contribute to both reduction of environmental impact and improvement of safety. Therefore, the above-mentioned non-azeotropic mixed refrigerant has less influence on the global environment and can improve safety and performance at the same time.

Further, the mixed refrigerant is a non-azeotropic mixed refrigerant, and the temperature of the non-azeotropic mixed refrigerant changes due to a phase change under the same pressure, and the temperature of the downstream side becomes higher than that of the upstream side in the evaporation process. Therefore, when a non-azeotropic mixed refrigerant is used as the refrigerant of the refrigerating apparatus 100, the temperature on the inlet side of the evaporator 4 is lower than that on the outlet side of the evaporator 4. In particular, since the refrigerating capacity of the mixed refrigerant containing R32 is improved even when it is used at a low temperature, the refrigerating apparatus 100 is often used for low-temperature equipment such as a showcase where the saturation temperature is below freezing. Therefore, when the mixed refrigerant containing R32 is used in a low temperature device having a saturation temperature lower than the freezing point, frost is generated in the evaporator 4.

FIG. 5 shows a Moriel diagram of a non-azeotropic mixed refrigerant used in the refrigerating apparatus 200 according to the second embodiment of the present invention. In the case of the non-azeotropic mixed refrigerant according to the second embodiment, the composition is as shown above, and as shown in FIG. 5, when the non-azeotropic mixed refrigerant is phase-changed under a constant pressure in a low temperature region, The temperature gradient of the non-azeotropic mixed refrigerant between the inlet and the outlet of the evaporator 4 is −5 ° C. That is, in the low temperature region, when the refrigerant flowing inside the evaporator 4 is heat-exchanged without causing a pressure loss, the temperature difference between the inlet and the outlet of the evaporator 4 is about 5 ° C. For example, the temperature on the inlet side of the evaporator 4 becomes −12 ° C., the temperature on the outlet side of the evaporator 4 becomes −7 ° C., and the temperature on the inlet side of the evaporator 4 drops significantly. Therefore, on the inlet side of the evaporator 4, where the temperature of the refrigerant is lower, the cooling of the air in contact with the heat transfer tube 41 and the fins 42 is promoted, the moisture contained in the air solidifies, and the amount of frost is easily formed. Is more than the outlet side of the evaporator 4. Therefore, the effect of uneven frost on the freezing performance of the freezing device 200 is also large.

Therefore, also in the second embodiment, the refrigerant saturation temperature difference between the inlet and the outlet of the evaporator 4 is calculated from the physical properties of the non-azeotropic mixed refrigerant. Then, in the refrigerating apparatus 200, the pressure difference of the refrigerant between the inlet and the outlet of the evaporator 4 is the pressure difference of the refrigerant at the inlet and the outlet of the evaporator 4 when the temperature of the refrigerant flowing through the evaporator 4 is made uniform. In the same manner, a pipe pressure loss may be applied to the refrigerant flowing through the evaporator 4.

From the above, as in the second embodiment, the refrigerant circulating in the refrigerating apparatus 200 has a composition of 36 wt% for R32, 30 wt% for R125, 14 wt% for R134a, 14 wt% for R1234yf, and 6 wt% for carbon dioxide. Even when a co-boiling mixed refrigerant is used, the piping pressure loss in the evaporator 4 is configured to be substantially the same as the temperature gradient of the refrigerant, so that the refrigerant temperature in the evaporator 4 becomes substantially uniform and the evaporator 4 is used. It is possible to prevent deterioration of heat exchange performance due to uneven deposition frost. At the same time, by using the non-azeotropic mixed refrigerant according to the second embodiment, the refrigerating apparatus 200 has less influence on the global environment and can simultaneously improve safety and refrigerating performance.

The composition of each refrigerant constituting the non-azeotropic mixed refrigerant of the second embodiment may be a refrigerant having a different composition ratio of each refrigerant in the range of less than ± 3 wt%. That is, the condition that the ratio X _R32 (wt%) of _R32 is 33 <X _R32 <39, the condition that the ratio X _R125 (wt%) of _R125 is 27 <X _R125 <33, and the ratio X _{R134a of R134a} ( The condition that (wt%) is 11 <X _R134a <17 and the ratio of _R1234yf X _R1234yf (wt%) 11 <X _R1234yf <17 and the ratio of carbon dioxide X _CO2 (wt%) is 3 <X _R125. A refrigerant that satisfies all of the conditions <9 and the condition that the total sum of X _R32 , X _R125 , X _R134a , X _R1234yf, and X _co2 is 100 (wt%) may be used.

The refrigerant that circulates in the refrigerating apparatus 200 of the second embodiment may be any of R448A, R449A, and R407F. R448A, R449A, and R407F are non-cobo-boiling mixed refrigerants, and regardless of which one is used, the pipe pressure loss applied to the refrigerant in the evaporator 4 is configured to be substantially the same as the temperature gradient of the refrigerant. It is possible to make the temperature of the refrigerant in the evaporator 4 substantially uniform and prevent deterioration of heat exchange performance due to uneven frost formation in the evaporator 4.

The physical properties of the non-azeotropic mixed refrigerant according to the second embodiment are similar to the physical properties of the R410A, and even if the R410A is put into the refrigerating apparatus 200 according to the second embodiment, it can be operated without any problem. .. However, R410A is a pseudo azeotropic mixed refrigerant and has almost no temperature gradient. That is, in FIG. 5, the isotherms of the refrigerant are substantially horizontal, as in the isotherms of the pseudo-azeotropic mixed refrigerant shown in the evaporator 4. Therefore, when R410A is used in the refrigerating apparatus 200 provided with the evaporator 4 designed for the non-azeotropic mixed refrigerant according to the second embodiment, the outlet side is due to the pressure loss when the refrigerant flows in the evaporator 4. It is conceivable that the pressure of the refrigerating apparatus 200 will decrease and the refrigerating capacity of the refrigerating apparatus 200 will decrease significantly.

Therefore, when R410A is used for the refrigerating apparatus 200, the evaporator 4 needs to be configured so that the pipe pressure loss of the heat transfer tube 41 is reduced in order to reduce the performance deterioration when R410A is used. For example, when the non-azeotropic mixed refrigerant according to the second embodiment is used, the refrigerant saturation temperature difference between the inlet and the outlet of the evaporator 4 in the low temperature region is about 5 ° C., so that the evaporator 4 corresponds to 5 ° C. It is configured to impart a pressure loss to the refrigerant. However, when R410A is used, the pressure loss in the evaporator 4 is set to a pressure loss equivalent to less than 5 ° C. in terms of the temperature gradient of the non-azeotropic mixed refrigerant.

For example, the heat transfer tube 41 of the evaporator 4 according to the second embodiment is configured so that the pressure loss is small with respect to the refrigerant flowing in the tube at a normal flow velocity, and the refrigerating device 200 uses R410A. At times, operate so that the refrigerant flows at a normal flow velocity. Then, the refrigerant flowing in the evaporator 4 flows so that the pressure loss becomes less than 5 ° C. in terms of the temperature gradient of the non-azeotropic mixed refrigerant, so that the refrigerant evaporates at substantially the same pressure as shown by the dotted line C shown in FIG. It flows out from the vessel 4. On the other hand, when the non-coborous mixed refrigerant according to the second embodiment is used, the refrigerant is allowed to flow at a flow rate faster than usual, and the heat transfer tube 41 is configured so that the pressure loss of the refrigerant in the pipe becomes large at a high flow rate. Just do it. When the flow velocity of the refrigerant is increased, the pressure loss of the refrigerant in the evaporator 4 becomes large, and the pressure at the outlet becomes lower than the inlet of the evaporator 4 as shown by the solid line D shown in FIG. 5, and the evaporator 4 There is no temperature difference between the inlet and outlet of the refrigerant, and no uneven frost occurs. By the means as described above, the refrigerating apparatus 200 can utilize both the non-azeotropic mixed refrigerant and the pseudo-azeotropic mixed refrigerant without lowering the refrigerating capacity.

FIG. 6 is a schematic view showing the configuration of the evaporator 24 of the refrigerating device 200 according to the second embodiment of the present invention. For example, the heat transfer tube 41 of the evaporator 24 according to the second embodiment is configured to give a predetermined pressure loss to the refrigerant flowing in the tube. When R410A is used, the refrigerating apparatus 200 is configured so that the number of flow paths of the refrigerant flowing through the evaporator 24, that is, the number of passes is five as shown in FIG. On the other hand, when the non-azeotropic mixed refrigerant according to the second embodiment is used, the refrigerating apparatus 200 switches the flow path of the refrigerant flowing through the evaporator 24, and the number of passes of the refrigerant is one as shown in FIG. Is configured to pass through the evaporator 24. In the evaporator 24 shown in FIG. 6, each heat transfer tube 41 is connected by a U-shaped tube 45 at the end of the evaporator 24, and the flow path is lengthened by the refrigerant being folded back and flowing at both ends of the evaporator 24. .. Since the flow path of the refrigerant is long, the pressure of the refrigerant passing through the evaporator 24 decreases due to the loss of the heat transfer tube 41. With the above configuration, when a pseudo-azeotropic mixed refrigerant such as R410A is used in the refrigerating apparatus 200, the pressure loss of the refrigerant is reduced by shortening the flow path. When a non-azeotropic mixed refrigerant is used in the refrigerating apparatus 200, the pressure loss of the refrigerant can be increased by lengthening the flow path. By the above means, the refrigerating apparatus 200 can utilize both the pseudo azeotropic mixed refrigerant and the non-azeotropic mixed refrigerant without lowering the refrigerating capacity.

(9) According to the refrigerating apparatus 200 according to the second embodiment, the refrigerant is a mixed refrigerant of R32, R125, R134a, R1234yf, and carbon dioxide, and the ratio of _R32 X _R32 (wt%) is , 33 wt% <X _R32 <39 wt%, the ratio of _R125 X _R125 (wt%) is 27 wt% <X _R125 <33 wt%, and the ratio of _R134a X _R134a (wt%) is 11 wt. The condition that% <X _R134a <17 wt% and the ratio of _R1234yf X _R1234yf (wt%) is 11 wt% <X _R1234yf <17 wt% and the ratio of carbon dioxide X _CO2 (wt%) is 3 wt%. The condition that <X _CO2 <9 wt% and the condition that the total X _{total of} X _R32 , X _R125 , X _R134a , X _R1234yf , and X _{CO 2} is 100 wt% are all satisfied.
With such a configuration, the refrigerating apparatus 200 has less influence on the global environment and can improve safety and refrigerating performance at the same time.

(10) According to the refrigerating apparatus 200 according to the second embodiment, the refrigerant is R448A, R449A, or R407F.
(11) According to the refrigerating apparatus 200 according to the second embodiment, the refrigerating cycle is at least one of R32, R125, R134a, R1234yf, and carbon dioxide mixed refrigerants, R448A, R449A, and R407F. The above-mentioned refrigerant and R410A can be shared. With such a configuration, the refrigerating apparatus 200 can be used for various purposes such as low temperature equipment.

(12) According to the operation method of the refrigerating apparatus 200 according to the second embodiment, the pressure in the pipe between the inlet and the outlet is changed by changing the length of the heat transfer pipe 41 of the evaporator 24 through which the refrigerant passes. It has a pipeline length change step that changes the difference between the two.
With such a configuration, the refrigerating apparatus 200 can give a pressure loss to the refrigerant passing through the evaporator 24 depending on the refrigerant used. Therefore, since a plurality of types of refrigerants can be used in the refrigerating device 200, the refrigerating device 200 can be used for various purposes.

(13) According to the operation method of the refrigerating apparatus 200 according to the second embodiment, in the pipeline length changing step, the number of passes of the refrigerant passing through the evaporator 24 is changed, and the pressure in the pipeline between the inlet and the outlet is changed. Change the difference.
With this configuration, the refrigerating device 200 can change the pressure loss given to the refrigerant flowing in the evaporator 24 even in the evaporator 24 configured by the normal heat transfer tube 41. Further, by using the means described in (6) to (8) above in combination, the range of pressure loss given to the refrigerant flowing in the evaporator 24 is widened, and the pressure difference of the refrigerant between the inlet and outlet of the evaporator 24 is increased. It is also possible to make appropriate adjustments.

1 Compressor, 2 Condenser, 3 Decompressor, 4 Evaporator, 5 Refrigerant piping, 6 Condenser blower, 7 Evaporator blower, 20 Pressure sensor, 24 Evaporator, 30 Temperature sensor, 41 Heat transfer tube, 42 fins, 43 Refrigerant distributor, 44 header, 45 U-shaped tube, 50 cooler, 60 control unit, 100 refrigerating device, 200 refrigerating device, A dotted line, B dotted line, C dotted line, D solid line.

Claims (9)

A compressor, a condenser, a decompression device, and an evaporator are connected by a refrigerant pipe, and a refrigerating cycle in which the refrigerant circulates is provided.
The refrigerant is
R32 ratio X _R32 (wt%)
The condition that 33 wt% <X _R32 <39 wt% and
The ratio of _R125 X _R125 (wt%) is
The condition that 27 wt% <X _R125 <33 wt% and
The ratio of _R134a X _R134a (wt%) is
The condition that 11 wt% <X _R134a <17 wt% and
Ratio of R1234yf X _R1234yf (wt%)
The condition that 11 wt% <X _R1234yf <17 wt% and
The ratio of carbon dioxide X _CO2 (wt%) is
The condition that 3 wt% <X _CO2 <9 wt% and
The sum of X _R32 , X _R125 , X _R134a , X _R1234yf , and X _CO2 is X _total .
It is a mixed refrigerant or R410A that satisfies all the conditions of 100 wt%.
The evaporator is
According to the temperature gradient of the isotherm of the gas-liquid two-phase region of the non- co-boiling mixed refrigerant, the pressure in the pipeline during the evaporation process is lowered along the flow direction of the refrigerant .
In order for the refrigeration cycle to correspond to both the mixed refrigerant and R410A, the number of passes of the refrigerant passing through the evaporator is freely changed.
If the refrigerant is in the mixed refrigerant is characterized Rukoto reduce the number of paths of the refrigerant than when the refrigerant is R410A, refrigeration system. The heat transfer tube of the evaporator is
The refrigerating apparatus according to claim 1, wherein the cross-sectional area increases along the direction in which the refrigerant flows. The heat transfer tube of the evaporator is
The refrigerating apparatus according to claim 1, further comprising a resistance means that acts as a resistance to the flow of the refrigerant in the pipeline. The refrigerating apparatus according to any one of claims 1 to 3, wherein the pressure in the pipeline in the evaporation process is reduced by controlling the flow velocity of the refrigerant passing through the evaporator. The refrigerant is
R448A, R449A, or R407F, refrigeration system according to what Re of claims 1 to 4. A compressor, a condenser, a decompression device, and an evaporator are connected by a refrigerant pipe, and a refrigerating cycle in which the refrigerant circulates is provided.
The refrigerant is
R32 ratio X _R32 (wt%)
The condition that 33 wt% <X _R32 <39 wt% and
The ratio of _R125 X _R125 (wt%) is
The condition that 27 wt% <X _R125 <33 wt% and
The ratio of _R134a X _R134a (wt%) is
The condition that 11 wt% <X _R134a <17 wt% and
Ratio of R1234yf X _R1234yf (wt%)
The condition that 11 wt% <X _R1234yf <17 wt% and
The ratio of carbon dioxide X _CO2 (wt%) is
The condition that 3 wt% <X _CO2 <9 wt% and
The sum of X _R32 , X _R125 , X _R134a , X _R1234yf , and X _CO2 is X _total .
In a refrigerating apparatus, which is a mixed refrigerant or R410A that satisfies all the conditions of 100 wt% .
A detection step for detecting the pressure in the pipeline at the inlet of the evaporator and the outlet of the evaporator, and
A pressure adjustment step in which the difference in pressure in the pipeline between the inlet and the outlet is adjusted to the temperature gradient of the isotherm of the gas-liquid two-phase region of the refrigerant.
A line length changing step for changing the number of passes of the refrigerant passing through the evaporator and changing the difference in pressure in the line between the inlet and the outlet is provided .
The pipeline length changing step is
A method of operating a refrigerating apparatus , wherein when the refrigerant is the mixed refrigerant, the number of passes of the refrigerant is reduced as compared with the case where the refrigerant is R410A . The pressure adjustment step
The operation method of the refrigerating apparatus according to claim 6 , further comprising a flow velocity changing step of changing the difference in pressure in the pipeline between the inlet portion and the outlet portion by changing the flow velocity of the refrigerant flowing through the evaporator. .. The flow velocity changing step
The method for operating a refrigerating apparatus according to claim 7 , wherein the flow velocity of the refrigerant flowing through the evaporator is changed by changing the operating frequency of the compressor. The flow velocity changing step
The method for operating a refrigerating apparatus according to claim 7 or 8 , wherein the opening degree of the flow rate adjusting valve installed at the inlet of the evaporator is changed to change the flow velocity of the refrigerant flowing through the evaporator.

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