CN104126099A

CN104126099A - Refrigeration cycle device

Info

Publication number: CN104126099A
Application number: CN201380010056.9A
Authority: CN
Inventors: 薛隽; 远藤和广; 坪江宏明; 横关敦彦
Original assignee: Hitachi Appliances Inc
Current assignee: Hitachi Johnson Controls Air Conditioning Inc
Priority date: 2012-02-29
Filing date: 2013-01-16
Publication date: 2014-10-29
Anticipated expiration: 2033-01-16
Also published as: JP5696069B2; CN104126099B; WO2013128962A1; TWI522586B; JP2013178044A; TW201403011A

Abstract

The invention provides a refrigeration cycle device. The objective of the present invention is to achieve an excellent flow division characteristic under a wide range of usage conditions, without being influenced by the installation position of a refrigerant flow divider, or by manufacturing variations, or the like. This refrigeration cycle device is equipped with: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve (3) that decompresses the refrigerant condensed by the condenser; a flow divider (4) that is constructed separately from the expansion valve (3), and that divides the flow of the refrigerant decompressed by the expansion valve (3) into multiple flow paths formed in the interior of the flow divider; and an evaporator that vaporizes the refrigerant that has been divided by the flow divider (4). The expansion valve (3) and the flow divider (4) are arranged so as to satisfy the equations L/D<=1.2 G0.36 and L/D >=1.5, where L [m] is the distance from the throttle region (300) of the expansion valve (3) to the branching region (400) of the flow divider (4), D[m] is the inner diameter of a second connecting tube (32) of the expansion valve (3), and G[kg/(m<2>s)] is the mass velocity of the refrigerant flowing in the second connecting tube (32) of the expansion valve.

Description

Refrigeration cycle device

Technical Field

The present invention relates to a refrigeration cycle apparatus including an expansion valve and a refrigerant flow divider.

Background

As a background art in the present technical field, japanese patent application laid-open No. 2009-24937 (patent document 1) is known. An object of the conventional technology is to provide a refrigerant flow dividing chamber combined type expansion valve in which an expansion valve and a refrigerant flow divider are integrally formed, and which can easily cope with different numbers of passages.

The publication discloses the following: the valve body is composed of a valve chamber part and a branch chamber part. The valve chamber portion has the interior of the housing as a valve chamber and a partition wall separating the valve chamber and the refrigerant bypass chamber as a bottom wall. An inlet port for receiving the throttle portion therein and connecting the liquid pipe is formed in the housing. The branch chamber portion has a housing opened upward, and a port for connecting the plurality of branch tubes is formed in the housing. The valve chamber portion and the flow dividing chamber portion of the above-described structure are manufactured separately. The upper part of the separately prepared flow distribution chamber part is connected to the partition wall of the valve chamber part so as to be closed.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2009-24937

Summary of The Invention

Problems to be solved by the invention

However, in the conventional technique described in japanese patent application laid-open No. 2009-24937, when the valve chamber portion and the branch chamber portion are joined by brazing or welding, the heating position is close to the valve hole, the valve rod, and the like, and therefore, deformation of the valve hole and the like due to heat may be caused, and the flow rate characteristics and the aging resistance of the expansion valve may be greatly affected. Further, when the valve chamber portion and the branch chamber portion are screwed in place of the brazing or welding, there is a possibility that refrigerant leakage occurs.

In a refrigeration cycle apparatus including an expansion valve, a filter is provided in a refrigerant pipe connected to the expansion valve in order to prevent the expansion valve from being clogged due to the intrusion of foreign matter such as dust. However, according to the structure of the expansion valve described in the above patent document, the installation of the filter is not easy.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to improve the reliability of a refrigeration cycle apparatus and to realize a good flow dividing characteristic under a wide range of use conditions.

Solution scheme

To achieve the above object, for example, the structure described in the claims is adopted. The refrigeration cycle device is provided with: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor; an expansion valve 3 for decompressing the refrigerant condensed by the condenser; a refrigerant flow divider 4 which is formed separately from the expansion valve 3 and which divides the refrigerant decompressed by the expansion valve 3 into a plurality of flow paths formed inside the refrigerant flow divider 4; an evaporator for evaporating the refrigerant branched by the refrigerant flow divider 4, wherein the expansion valve 3 and the refrigerant flow divider 4 satisfy L/D of 1.2G or less^0.36And the L/D is more than or equal to 1.5. Wherein, L [ m ]]Is the distance, D [ m ], from the throttle region 300 of the expansion valve 3 to the branch region 400 of the refrigerant flow divider 4]Is the inner diameter, G [ kg/(m) of the second connecting pipe 32 of the expansion valve 3²s)]Is the mass velocity of the refrigerant flowing through second connection pipe 32.

Effects of the invention

According to the present invention, even when a flow divider having a simple structure is used, good flow dividing characteristics can be obtained under a wide range of use conditions without being affected by the installation posture, manufacturing variations, and the like of the refrigerant flow divider.

Drawings

Fig. 1 is a partial cross-sectional view showing a connection form between an expansion valve and a flow divider according to embodiment 1 of the present invention.

Fig. 2 is a configuration diagram of a refrigeration cycle apparatus according to embodiment 1 of the present invention.

Fig. 3 is an example of a visual experiment result, and shows a flow pattern of a gas-liquid two-phase flow in a pipe downstream of an expansion valve.

Fig. 4 is a graph showing the relationship between the distance Lt from the throttle region of the expansion valve, the tube inner diameter D, and the mass velocity G of the refrigerant in the tube, at which the flow state of the gas-liquid two-phase flow in the tube changes.

FIG. 5 shows the mass velocity G as 530 kg/(m)²s) and the result of measurement of the flow dividing characteristics under the experimental conditions where the dryness x is 0.15, show the variation in the mass flow rate ratio of the refrigerant to each branch.

FIG. 6 shows the mass velocity G as 530 kg/(m)²s) and the result of measurement of the flow dividing characteristics under the experimental conditions where the dryness x is 0.15, show the variation in the dryness of the refrigerant to each branch.

FIG. 7 shows the mass velocity G of 180 kg/(m)²s) and the result of measurement of the flow dividing characteristics under the experimental conditions where the dryness x is 0.15, show the variation in the mass flow rate ratio of the refrigerant to each branch.

FIG. 8 shows the mass velocity G of 180 kg/(m)²s) and the result of measurement of the flow dividing characteristics under the experimental conditions where the dryness x is 0.15, show the variation in the dryness of the refrigerant to each branch.

Fig. 9 is a diagram showing another example of the shunt according to embodiment 1 of the present invention, and shows a shape of a 12-branch structure.

Fig. 10 is a configuration diagram of a refrigeration cycle apparatus according to embodiment 2 of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example 1

Fig. 2 is an example of the configuration of the refrigeration cycle apparatus 100 according to the present embodiment, for example, an indoor air conditioner. Here, reference numeral 1 is a compressor, reference numeral 2 is a first heat exchanger, reference numeral 3 is an expansion valve, reference numeral 4 is a refrigerant flow divider, reference numeral 5 is a second heat exchanger, and reference numeral 6 is a four-way valve. The above-described essential devices are connected by refrigerant pipes to constitute the refrigeration cycle apparatus 100.

When the first heat exchanger 2 functions as a condenser and the second heat exchanger 5 functions as an evaporator, and the refrigerant circulates in the refrigeration cycle apparatus 100 in the order of the compressor 1 → the first heat exchanger 2 → the expansion valve 3 → the refrigerant flow divider 4 → the second heat exchanger 5 → the compressor 1 (indicated by solid arrows), the refrigerant having passed through the expansion valve 3 is in a gas-liquid two-phase state, and is divided by the refrigerant flow divider 4 via the refrigerant pipe 90 connecting the expansion valve 3 and the refrigerant flow divider 4.

The flow state of the gas-liquid two-phase flow flowing through the refrigerant pipe 90 is greatly affected by the use conditions of the refrigeration cycle apparatus 100, the installation posture or shape of the pipe 90, and the like. In many cases, the gas-liquid two-phase flow is a spring flow in which liquid slag containing small bubbles and gas columns alternately exist, a bubble flow, or an annular flow in which a liquid film exists on the pipe wall and a plurality of liquid droplets are entrained in the center of the cross section of the gas phase pipe, and the distribution of the density and the flow velocity is not uniform. This causes a large difference in the mass flow rate and the dryness (the ratio of the gas phase to the total mass flow rate) of the gas-liquid two-phase flow to each branch when the flow is split by the refrigerant splitter 4.

On the other hand, if the refrigerant flow split at the refrigerant flow divider 4 is not appropriate, problems such as a reduction in performance of the second heat exchanger 5 and the refrigeration cycle device 100 functioning as evaporators, excessive backflow to the compressor 1, and the like may occur, and therefore the flow split of the gas-liquid two-phase flow is an important problem.

In addition, the refrigeration cycle apparatus 100 can switch the flow direction of the refrigerant by the four-way valve 6. In this case, the first heat exchanger 2 functions as an evaporator, the second heat exchanger 5 functions as a condenser, and the refrigerant circulates in the refrigeration cycle apparatus 100 in the order of the compressor 1 → the second heat exchanger 5 → the refrigerant flow divider 4 → the expansion valve 3 → the first heat exchanger 2 → the compressor 1 (indicated by a broken arrow). Accordingly, the refrigerant flow divider 4 does not have a function of dividing the refrigerant, but instead merges the liquid refrigerant passing through the second heat exchanger 5 of the condenser, and sends the merged refrigerant to the expansion valve 3 via the refrigerant pipe 90. However, when dust or the like is mixed into the refrigerant, the expansion valve 3 may be clogged due to the entry of the foreign matter, and the refrigeration cycle apparatus 100 may be broken, and therefore, a filter needs to be provided between the refrigerant flow divider 4 and the expansion valve 3.

Next, a method for solving the above problem will be described with reference to fig. 1.

Fig. 1 is an example of a partial sectional view showing a connection form between an expansion valve 3 and a refrigerant flow divider 4. Here, solid arrows indicate the flow of the refrigerant when the refrigerant flow divider 4 performs the function of dividing the refrigerant. Further, reference numeral 70 denotes a filter that prevents foreign matter from entering the expansion valve 3, and reference numerals 80a, 80b, 80c, and 80d denote branch pipes that send the refrigerant branched by the refrigerant flow divider 4 to the second heat exchanger 5.

The expansion valve 3 includes a valve main body 33, a first connection pipe 31 connecting the valve main body 33 and the first heat exchanger 2, and a second connection pipe 32 connecting the valve main body 33 and the refrigerant flow divider 4.

A valve hole 34 and a needle 35 movable in the axial direction by the operation of a drive device are built in the valve main body 33. An annular throttle area 300 is formed between the valve hole 34 and the needle 35, where the liquid refrigerant flowing in from the first connection pipe 31 is decompressed and brought into a gas-liquid two-phase state. The flow passage area of the throttle region 300 can be adjusted by moving the needle 35 according to the use condition of the refrigeration cycle apparatus 100.

The refrigerant flow divider 4 is manufactured by drawing, and is composed of a first connecting portion 41 connected to the expansion valve 3, a straight pipe portion 42 provided on the downstream side of the first connecting portion, a second connecting portion 43 provided on the downstream side of the straight pipe portion 42, and a branch portion 44 provided on the downstream side of the second connecting portion 43. Further, a branch region 400 that divides the refrigerant is formed between the second coupling portion 43 and the branch portion 44.

The first connecting portion 41 is formed in a manner to match the second connecting pipe 32 of the expansion valve 3, and is joined by brazing to the second connecting pipe 32 inserted therein. The straight tube portion 42 has an inner diameter equal to that of the second connecting tube 32, and the filter 70 is fixed thereto by caulking. The second connecting portion 43 gradually enlarges the flow path area from the straight pipe portion 42 toward the branch portion 44. The branch portion 44 has a clover shape, and is joined to the branch pipes 80a, 80b, 80c, 80d inserted therein by brazing. In the present embodiment, the branch pipe 80d is provided coaxially with the refrigerant flow divider 4, and on the outside thereof, the branch pipes 80a, 80b, and 80c are provided at equal intervals on the circumference centering on the axis of the refrigerant flow divider 4.

In fig. 1, reference symbol L denotes a distance from the throttle region 300 of the expansion valve 3 to the branch region 400 of the refrigerant flow divider 4, and reference symbol D denotes an inner diameter of the second connection pipe 32 of the expansion valve 3.

In the present invention, the expansion valve 3 and the refrigerant flow divider 4 are preferably set so as to satisfy L/D ≦ 1.2G^0.36Is configured in the same manner as (1). Wherein G is the refrigerant flowing through the second connection pipe 32 of the expansion valve 3The mass velocity. The reason for this will be described below with reference to fig. 3 to 8.

Fig. 3 and 4 show the results of visual experiments in which the mass velocity G of the refrigerant in the pipe is changed for the gas-liquid two-phase flow downstream of the expansion valve. In the visual experiment, R410A was used as the refrigerant, and the flow was set to a vertically downward flow. Further, the inner diameter D of the glass tube was 8 mm.

Fig. 3 shows an example of the result of the visual experiment, and shows that the mass velocity G is 180 kg/(m)²s), and the dryness x is 0.15. As shown in fig. 3, the gas-liquid two-phase flow is in a swirling jet flow state in a region from the throttle region 300 of the expansion valve 3 to about 60mm downstream, and appears as a white turbid liquid. In this case, since the gas phase and the liquid phase of the refrigerant are mixed well, if the refrigerant is branched in this state, a good flow-dividing characteristic can be achieved. On the other hand, in a region of about 60mm or less from the throttle region 300, the gas-liquid two-phase flow becomes a bubble annular flow, and a liquid film is formed on the pipe wall and a plurality of fine bubbles are entrained. In this case, the refrigerant is in a state of being separated into a gas phase and a liquid phase, and the thickness of the liquid film along the pipe wall is not uniform, so that a good flow dividing property cannot be expected.

Fig. 4 shows, based on the above-described observation results, the distance L from the throttle region 300 of the expansion valve 3, which changes the flow state of the gas-liquid two-phase flow in the pipe, to the throttle region 300 of the expansion valve 3_t(hereinafter referred to as transition distance), the tube inner diameter D, and the mass velocity G of the refrigerant in the tube. Here, the horizontal axis represents the mass velocity G [ kg/(m)²s)]The vertical axis represents the transition distance L_t[m]And the inner diameter D [ m ] of the pipe]The ratio of (a) to (b). In addition, a Δ mark in the figure indicates an observation result of a visualization experiment, and a dotted line is an approximate curve of power based on the observation result.

As can be seen from FIG. 4, the transition distance L_tThe mass velocity G increases and the length of the film increases, and L is satisfied_t/D＝1.2G^0.36。

According to the above-described visual experimental results, using a state in which the gas phase and the liquid phase of the refrigerant downstream of the expansion valve are well mixed, in order to obtain good flow dividing characteristics, it is preferable to set the expansion valve 3 and the refrigerant flow divider 4 so as to satisfy L/D ≦ 1.2G^0.36The mode of (2).

When the mass velocity G varies according to the usage conditions of the refrigeration cycle apparatus 100, the minimum value G of the mass velocity is preferably equal to the minimum value G of the mass velocity_minCorrespondingly, the expansion valve 3 and the refrigerant flow divider 4 are arranged to satisfy the condition that L/D is less than or equal to 1.2G_min ^0.36The mode of (2). This enables to realize a good flow dividing characteristic under all use conditions.

FIGS. 5 to 8 show the change (180 to 530 kg/(m) in the mass velocity G of the refrigerant in the tube by using the refrigerant flow divider 4 (4-branch) in the drawing process having the structure shown in FIG. 1²s)) and a portion of the results of measuring the shunt characteristic.

FIGS. 5 and 6 show the mass velocity G as 530 kg/(m)²s), and the measurement result under the experimental condition where the dryness x is 0.15, and shows the mass flow rate ratio of the refrigerant to each branch (the ratio of the mass flow rate to the branch i to the total mass flow rate) and the deviation of the dryness. In addition, fig. 7 and 8 show that the mass velocity G is 180 kg/(m)²s), and the result of measurement under the experimental condition where the dryness x is 0.15, and shows the mass flow rate ratio of the refrigerant to each branch and the variation in dryness. The deviation of the mass flow rate ratio is a difference between the actual flow rate of the refrigerant flowing to the branch i and the ideal flow rate ratio (i.e., 25%) at the time of equal flow rate distribution. The deviation of the dryness is the difference between the actual dryness of the refrigerant flowing toward branch i and the ideal dryness at the time of equal dryness.

In addition, in fig. 5 to 8, ● denotes a result under the condition that L/D is 7.5 and θ is 0 °, o denotes a result under the condition that L/D is 7.5 and θ is 15 °, α denotes a result under the condition that L/D is 37.5 and θ is 0 °, and L/D is 37.5 and θ is 15 °.Wherein L/D is 7.5, and mass speed G is 180 kg/(m)²s) and the transition point of the refrigerant flow state under the experimental condition that the dryness x is 0.15 (see fig. 3), L/D ≦ 1.2G is satisfied for all experimental conditions^0.36. However, L/D ≦ 1.2G for 37.5 for all experimental conditions but not L/D ≦ 1.2G^0.36. Note that θ represents an angle at which the axis of the refrigerant flow divider 4 is inclined with respect to the vertical direction, and when θ is 15 °, the branch pipe 80a is located at the lowermost position in the vertical direction.

As shown in fig. 5 to 8, when the installation posture of the refrigerant flow diverter 4 is vertical, the difference in the mass flow rate ratio between the branches and the dryness is smaller when L/D is 7.5(●) than when L/D is 37.5(°). In addition, in the case where the refrigerant flow splitter 4 is inclined by 15 ° with respect to the vertical direction, the splitting characteristic changes significantly when L/D is 37.5 (), whereas the change in the splitting characteristic is hardly visible when L/D is 7.5 ().

From the above results, it is understood that the transition distance L corresponding to the mass velocity G of the refrigerant in the pipe downstream of the expansion valve is set_tOr below, the refrigerant flow divider 4 is provided to divide the gas-liquid two-phase flow in a gas-liquid well mixed state, and even if a flow divider formed by drawing having a simple structure is used, good flow dividing characteristics can be obtained under a wide range of use conditions without being affected by the installation posture of the flow divider. Therefore, the expansion valve 3 and the refrigerant flow divider 4 are preferably selected so as to satisfy L/D ≦ 1.2G^0.36The mode of (2).

In the present invention, the expansion valve 3 and the refrigerant flow divider 4 are preferably arranged so as to satisfy L/D.gtoreq.1.5. Thus, when the expansion valve 3 and the refrigerant flow divider 4 are brazed, the heating position is located in the second connection pipe 32, and a constant distance from the valve main body 33 can be obtained, so that deformation of the valve hole and the like due to heat can be prevented. At the same time, a filter 70 for preventing foreign matters from entering the expansion valve 3 can be provided in the straight tube portion 42 of the refrigerant flow divider 4.

In the present invention, at least one of the plurality of flow paths formed inside the refrigerant flow divider 4 is provided inside the other flow paths. This enables the refrigerant flow divider 4 to be made compact, which contributes to reducing the cost of the product in addition to reducing the installation space. Further, as shown in fig. 5 to 8, since the mass flow rate and the dryness of the refrigerant flowing through the branch pipe 80d provided coaxially with the refrigerant flow divider 4 are substantially the same as those of the refrigerant flowing through the branch pipes 80a, 80b, and 80c provided at equal intervals on the circumference, there is no fear that the flow dividing characteristics are impaired.

In the above embodiment, the case where the 4-branch refrigerant flow divider 4 is used has been described. However, the number of branches of the refrigerant flow divider 4 according to the present invention is not limited to two or more. For example, a 12-branched structure as shown in fig. 9 may be employed. Further, although the method of manufacturing the refrigerant flow divider 4 is preferably low-cost drawing, it may be cutting, pressing, or the like.

Example 2

Fig. 10 shows an example of the configuration of the refrigeration cycle apparatus 101 according to embodiment 2, for example, a box-type air conditioner. Here, reference numeral 1 denotes a compressor, reference numeral 2 denotes a first heat exchanger, reference numerals 3a and 3b denote expansion valves, reference numerals 4a and 4b denote refrigerant splitters, reference numeral 5 denotes a second heat exchanger, reference numeral 6 denotes a four-way valve, and reference numeral 91 denotes a connection pipe. Wherein both the first heat exchanger 2 and the second heat exchanger 5 have a multi-pass configuration.

When the first heat exchanger 2 functions as a condenser and the second heat exchanger 5 functions as an evaporator, the liquid refrigerant that has joined the flow divider 4a via the first heat exchanger 2 passes through the expansion valve 3a and the connection pipe 91, is decompressed by the expansion valve 3b to become a gas-liquid two-phase state, and then is divided by the flow divider 4b and flows into the second heat exchanger 5, as indicated by solid arrows in the figure.

On the other hand, when the first heat exchanger 2 functions as an evaporator and the second heat exchanger 5 functions as a condenser as the flow direction of the refrigerant in the refrigeration cycle apparatus 101 is switched by the four-way valve 6, the liquid refrigerant that has merged in the flow divider 4b via the second heat exchanger 5 passes through the expansion valve 3b and the connection pipe 91 as indicated by the broken-line arrows in the drawing, is decompressed by the expansion valve 3a to become a gas-liquid two-phase state, and then is divided by the flow divider 4b and flows into the first heat exchanger 2.

In the present embodiment, the expansion valve 3a and the flow divider 4a are preferably selected so as to satisfy L/D ≦ 1.2G_a ^0.36Is arranged in such a way that the expansion valve 3b and the flow divider 4b satisfy the condition that L/D is less than or equal to 1.2G_b ^0.36The mode of (2). Wherein G is_aIs the mass velocity G at the time when the flow divider 4a divides the refrigerant passing through the expansion valve 3a_bIs the mass velocity at which the flow divider 4b divides the refrigerant having passed through the expansion valve 3 b.

Thus, the refrigeration cycle apparatus 101 can achieve good flow dividing characteristics under all usage conditions regardless of the flow direction of the refrigerant.

Description of reference numerals:

3 expansion valve

4 refrigerant flow divider

300 throttle area

400 branch region

Claims

1. A refrigeration cycle apparatus, characterized in that,

the refrigeration cycle device is provided with:

a compressor that compresses a refrigerant;

a condenser that condenses the refrigerant compressed by the compressor;

an expansion valve for decompressing the refrigerant condensed by the condenser;

a flow divider that is configured separately from the expansion valve and that divides the refrigerant decompressed by the expansion valve into a plurality of flow paths formed inside the flow divider; and

an evaporator for evaporating the refrigerant branched by the flow divider,

the expansion valve and the flow divider are configured in such a way as to satisfy the following equation:

L/D≤1.2G^0.36

wherein,

l [ m ]: distance from throttle region of expansion valve to branch region of flow divider

D [ m ]: inner diameter of second connection pipe of expansion valve

G[kg/(m²s)]: the mass velocity of the refrigerant flowing in the second connection pipe of the expansion valve.

2. The refrigeration cycle apparatus according to claim 1,

the flow divider is configured in a manner that satisfies the following equation:

L/D≥1.5

wherein,

D [ m ]: and the inner diameter of the second connection pipe of the expansion valve.

3. The refrigeration cycle apparatus according to claim 1,

at least one of the plurality of flow paths formed inside the flow divider is provided inside the other flow paths.

4. The refrigeration cycle apparatus according to claim 1,

the flow divider is formed by drawing.