WO2009142101A1

WO2009142101A1 - Refrigeration cycle

Info

Publication number: WO2009142101A1
Application number: PCT/JP2009/058336
Authority: WO
Inventors: 金子智
Original assignee: サンデン株式会社
Priority date: 2008-05-20
Filing date: 2009-04-28
Publication date: 2009-11-26
Also published as: EP2309208A1; CN102037292A; JP5180680B2; EP2309208A4; JP2009281610A; US20110067435A1; EP2309208B1

Abstract

A refrigeration cycle provided with a compressor, a condenser, a pressure reducing and expanding means, an evaporator, and an inner heat exchanger for exchanging heat between the refrigerant on the exit side of the condenser and the refrigerant on the exit side of the evaporator, wherein the refrigeration cycle uses R1234yf as the refrigerant and the amount of heat exchange by the inner heat exchanger is greater than or equal to a specific level previously obtained by simulation or test. When a currently used refrigerant is changed to a new refrigerant which is R1234yf, the refrigeration cycle can be operated with refrigeration capacity the same as or greater than that of refrigeration cycles using R134a which is a conventional refrigerant.

Description

Refrigeration cycle

The present invention relates to a refrigeration cycle, and particularly to a refrigeration cycle that can be operated with a high refrigeration capacity when a new refrigerant is used.

For example, a vapor compression refrigeration cycle used for a vehicle air conditioner or the like has a basic structure as shown in FIG. In FIG. 1, a refrigeration cycle 1 includes a compressor 2 for compressing refrigerant, a condenser 3 for condensing the compressed refrigerant, an expansion valve 4 as decompression / expansion means for decompressing / expanding the condensed refrigerant, An evaporator 5 that evaporates the expanded refrigerant, and an internal heat exchanger 6 that performs heat exchange between the condenser outlet-side refrigerant and the evaporator outlet-side refrigerant are provided. It is circulated in the direction of the arrow while changing the state. Thus, it is known that providing the internal heat exchanger 6 in the refrigeration cycle 1 can generally improve the refrigeration capacity. However, when R134a, which is a typical refrigerant at present, is used, since the effect of the internal heat exchanger 6 is relatively low, it is actually not used in practice.

As described above, R134a can be cited as a typical current refrigerant, but research and development of a new refrigerant is being conducted with the aim of further improving the global warming potential (GWP) (for example, non-patented). Reference 1). Recently, R1234yf has been announced as a new refrigerant aiming at such improvements, and it has become possible to conduct tests and research on application to refrigeration cycles used in, for example, vehicle air conditioners. .

However, when the new refrigerant R1234yf is simply applied to the current refrigeration cycle as it is, there is a high possibility that both the refrigeration capacity and the coefficient of performance (COP) will be lower than the refrigeration cycle using the current refrigerant R134a. In that case, in order to improve the refrigerating capacity, it is considered effective to use the internal heat exchanger 6 as described above, but the degree of the effect is not clarified.

Accordingly, an object of the present invention is to pay attention to the appearance of the new refrigerant as described above, and particularly when the used refrigerant is changed to a specific new refrigerant R1234yf, a high refrigeration capacity equal to or higher than that of the conventional refrigeration cycle using the refrigerant R134a. It is to provide a refrigeration cycle that can be operated with.

In order to solve the above problems, a refrigeration cycle according to the present invention includes a compressor that compresses a refrigerant, a condenser that condenses the compressed refrigerant, a decompression / expansion unit that decompresses / expands the condensed refrigerant, and a decompression / expansion unit. In a refrigeration cycle comprising an evaporator for evaporating the expanded refrigerant, and an internal heat exchanger for exchanging heat between the condenser outlet side refrigerant and the evaporator outlet side refrigerant, R1234yf is used as the refrigerant, The heat exchange amount by the internal heat exchanger is set to a predetermined value or more obtained in advance by simulation or test.

FIG. 2 shows that the internal heat exchanger is not used under the same calculation conditions (condensation temperature, evaporation temperature, degree of superheat, degree of supercooling, etc.) in the refrigeration cycle having the same basic configuration as shown in FIG. When the current refrigerant R134a is used under the conditions and the new refrigerant R1234yf is used under the conditions of using the internal heat exchanger, the calculation results of the refrigerating capacity are compared. When this new refrigerant R1234yf is used, the internal heat exchanger is used. It shows how to improve the refrigerating capacity by using The horizontal axis in FIG. 2 indicates the heat exchange amount of the internal heat exchanger (the capacity of the internal heat exchanger), and the vertical axis indicates the refrigeration capacity of the entire refrigeration cycle. When the current refrigerant R134a is used under conditions where the internal heat exchanger is not used (because the internal heat exchanger is not used, it is displayed as a constant refrigeration capacity with respect to the heat exchange amount of the internal heat exchanger) In comparison, when a new refrigerant R1234yf having different characteristics from R134a is used, the refrigeration capacity changes as shown in FIG. 2 due to the installation of the internal heat exchanger. That is, if the amount of heat exchange by the internal heat exchanger is greater than a certain value, that is, 0.7 kW or more in the comparative characteristic diagram shown in FIG. 2 (if entering the region of 0.7 kW or more), this new refrigerant R1234yf In the case of use, it turns out that the refrigerating capacity improvement effect by an internal heat exchanger installation is acquired reliably. However, when the amount of heat exchange by the internal heat exchanger is smaller than a certain value, in the comparative characteristic diagram shown in FIG. 2, when it is smaller than 0.7 kW, the case of R1234yf is better than the case of R134a. It can be seen that the refrigeration capacity is low, and the effect of installing the internal heat exchanger cannot be obtained as compared with the case of R134a. Therefore, only when the amount of heat exchange by the internal heat exchanger is set to a certain value (that is, a predetermined value) or more, when using R1234yf, a refrigerating capacity equal to or higher than that of R134a is obtained, and the refrigerating capacity is actually reduced. It turns out that it can improve. The present invention is based on this technical idea, and when using the new refrigerant R1234yf as a refrigerant, the heat exchange amount by the internal heat exchanger is set to a predetermined value or more obtained in advance by simulation or test. To do. That is, the right region (region indicated by hatching) of the intersection of the characteristic line in the case of R134a and the characteristic line in the case of R1234yf in FIG. 2 is used. In other words, the refrigerating capacity when the predetermined value of the heat exchange amount by the internal heat exchanger is the same under the same condition when R1234yf is used as the refrigerant is the refrigeration cycle when R134a is used as the refrigerant. It is set to be more than the overall refrigeration capacity.

In order to set the heat exchange amount by the internal heat exchanger to a predetermined value or more as described above, specifically, if the performance of the evaporator or condenser used in each refrigeration cycle is known in advance, the internal heat By arbitrarily adjusting the size, thermal efficiency, etc. of the exchanger, it is possible to set the value to a predetermined value or more as described above. In the refrigeration cycle made based on such an idea, since the approximate capacity of the internal heat exchanger is known in advance, depending on the degree of superheat of the outlet side refrigerant to the compressor side of the internal heat exchanger, By appropriately controlling the opening of the decompression / expansion means, as described above, a refrigeration capacity that is higher than the refrigeration capacity when R134a is used as the refrigeration capacity of the entire refrigeration cycle can be stably obtained.

Such a refrigeration cycle according to the present invention is basically applicable to any refrigeration cycle in which the new refrigerant R1234yf is to be used. However, a vehicle air conditioner in which efficient operation is required stably over a long period of time. Suitable for the refrigeration cycle used in the apparatus.

According to the refrigeration cycle according to the present invention, when the refrigerant used is changed to R1234yf, which is a new refrigerant, a high refrigeration capacity equal to or higher than that when the conventional refrigerant R134a is used can be realized, and the new refrigerant R1234yf itself is Improvement characteristics such as excellent global warming potential (GWP) can be exhibited.

It is a schematic block diagram which shows basic equipment arrangement | positioning of the refrigerating cycle made into object by this invention. It is a related figure of the internal heat exchanger heat exchange amount and the refrigerating capacity which compared the characteristic of refrigerant | coolant R1234yf and R134a. It is a related figure of the condensation temperature in the case of using refrigerant | coolant R1234yf and an internal heat exchanger capability ratio. It is a Mollier diagram which shows an example of the driving | running state of the refrigerating cycle at the time of condition with refrigerant | coolants R1234yf and R134a. It is a Mollier diagram which shows an example of the driving | running state of the refrigerating cycle at the time of another conditions of refrigerant | coolant R1234yf and R134a. It is a Mollier diagram which shows an example of the driving | running state of the refrigerating cycle at the time of another condition of refrigerant | coolants R1234yf and R134a.

Hereinafter, the present invention will be described together with embodiments with reference to the drawings.
The basic configuration of the refrigeration cycle installation device according to the present invention may be the same as that shown in FIG. In FIG. 1, as described above, the refrigeration cycle 1 includes a compressor 2 that compresses refrigerant, a condenser 3 that condenses the compressed refrigerant, and expansion as decompression / expansion means that decompresses and expands the condensed refrigerant. A valve 4, an evaporator 5 that evaporates the decompressed and expanded refrigerant, and an internal heat exchanger 6 that performs heat exchange between the condenser outlet-side refrigerant and the evaporator outlet-side refrigerant are provided.

Further, as described above, in the present invention, basically, the right side area (the area indicated by hatching) of the intersection of the characteristic line in the case of R134a and the characteristic line in the case of R1234yf shown in FIG. That is, in this region, when the new refrigerant R1234yf is used, the refrigeration capacity can be improved as compared with the conventional refrigerant R134a by providing an internal heat exchanger. Therefore, in the internal heat exchanger heat exchange amount condition at the intersection of the characteristic line in the case of R134a and the characteristic line in the case of R1234yf in FIG. 2 described above, for example, when the condensation temperature of the refrigerant is changed, A characteristic A in FIG. 3 shows how the capacity improvement effect (capacity ratio of the internal heat exchanger) by the internal heat exchanger with respect to the refrigeration capacity of the entire cycle becomes. FIG. 3 shows the relationship of the capacity ratio of the internal heat exchanger to the refrigeration capacity of the entire refrigeration cycle with respect to the condensation temperature, assuming that the efficiency of the internal heat exchanger is 100%. This is characteristic B. That is, if the capacity of the internal heat exchanger is between the characteristic curve A and the characteristic curve B, the effect of improving the refrigerating capacity equal to or higher than that when the R134a is used can be obtained. Since the efficiency of the vessel is less than 100%, the actual setting or control region is located between these characteristic curves A and B.

The intersection of the characteristic curves A and B in the calculation result shown in FIG. 3 is located at a position where the capacity ratio of the internal heat exchanger to the refrigeration capacity is 6.6%, so that the capacity ratio is 7% or more. Then, from the relational characteristics shown in FIG. 3, the effect of improving the refrigerating capacity is surely obtained by the internal heat exchanger. Although the upper limit value of the capacity ratio is not particularly limited, the calculation result shown in FIG. 3 confirms that the effect of improving the refrigeration capacity is surely obtained up to about 30%.

Table 1 shows an example of calculation results under certain conditions in the case of R134a and R1234yf as described above. The prerequisites for the calculation are as follows.
Evaporation temperature: 0deg
・ Condensation temperature: 50deg
-Evaporator outlet superheat degree: 5deg
・ Condenser outlet supercooling degree: 5deg
・ Heat exchanger ・ Circuit pressure loss: None assumed ・ Compressor efficiency: 100% assumed

In the case of the new refrigerant R1234yf, by increasing the heat exchange amount of the internal heat exchanger, the refrigeration capacity per unit volume becomes equal to or higher than that of the conventional refrigerant R134a as shown in the part surrounded by the bold line in Table 1. I understand that I can do it. Therefore, it is not necessary to increase the speed of the compressor. Further, since the compressor suction refrigerant density is reduced, the refrigerant circulation amount is reduced, and the pressure loss can be reduced. Further, the degree of superheat of the compressor suction side refrigerant increases, the compressor discharge temperature becomes higher than R134a, and the efficiency can be improved. Furthermore, since the increase in compressor power (power consumption) is relatively small, the coefficient of performance (COP) can be equal to or higher than that of R134a.

Also, examples of the result of comparing R134a and R1234yf on the Mollier diagram are shown in FIGS. 4 to 6 show cases where the temperature efficiency of the internal heat exchanger in the case of R1234yf is different. The conditions in each figure are as follows.

(1) Mollier diagram shown in FIG.
Evaporation temperature: 0deg
・ Condensation temperature: 50deg
-Evaporator outlet superheat degree: 5deg
・ Condenser outlet supercooling degree: 5deg
・ R134a has no internal heat exchanger ・ R1234yf has an internal heat exchanger and its temperature efficiency is 75.3%

(2) Mollier diagram shown in FIG.
Evaporation temperature: 0deg
・ Condensation temperature: 50deg
-Evaporator outlet superheat degree: 5deg
・ Condenser outlet supercooling degree: 5deg
・ R134a has no internal heat exchanger ・ R1234yf has an internal heat exchanger and its temperature efficiency is 93.0%

(3) Mollier diagram shown in FIG.
Evaporation temperature: 0deg
・ Condensation temperature: 50deg
-Evaporator outlet superheat degree: 5deg
・ Condenser outlet supercooling degree: 5deg
・ R134a has no internal heat exchanger ・ R1234yf has an internal heat exchanger and its temperature efficiency is 99.9%

In addition, although each example in the above is shown as a simulation result by calculation, separately from this, the above-mentioned predetermined value obtained by an actual test and determined by referring to the above-mentioned predetermined value or both the simulation result and the test result. It is also possible to use a value.

The refrigeration cycle according to the present invention can be applied to any refrigeration cycle in which R1234yf is scheduled to be used, and is particularly suitable as a refrigeration cycle used in a vehicle air conditioner.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 3 Condenser 4 Expansion valve 5 as decompression / expansion means Evaporator 6 Internal heat exchanger

Claims

A compressor that compresses the refrigerant; a condenser that condenses the compressed refrigerant; a decompression / expansion means that decompresses / expands the condensed refrigerant; an evaporator that evaporates the decompressed / expanded refrigerant; and a condenser outlet-side refrigerant; In a refrigeration cycle including an internal heat exchanger that exchanges heat with the evaporator outlet side refrigerant, R1234yf is used as the refrigerant, and the amount of heat exchange by the internal heat exchanger is obtained in advance by simulation or test. A refrigeration cycle characterized by having a predetermined value or more.
When the predetermined value of the heat exchange amount by the internal heat exchanger is the same, the refrigerating capacity as the whole refrigerating cycle when R1234yf is used as the refrigerant is the refrigerating capacity as the whole refrigerating cycle when R134a is used as the refrigerant. The refrigeration cycle according to claim 1, wherein the refrigeration cycle is set to be equal to or greater than the capacity.
The refrigeration cycle according to claim 1, wherein the predetermined value of the heat exchange amount by the internal heat exchanger is set as a capacity ratio with respect to the refrigeration capacity of the entire refrigeration cycle.
The refrigeration cycle according to claim 3, wherein a capacity ratio of a predetermined value of a heat exchange amount by the internal heat exchanger to a refrigeration capacity as a whole of the refrigeration cycle is set to 7% or more.
The refrigeration cycle according to claim 1, wherein the opening degree of the decompression / expansion means is controlled according to the degree of superheat of the outlet side refrigerant to the compressor side of the internal heat exchanger.
The refrigeration cycle according to claim 1, which is used for a vehicle air conditioner.