JPH08254373A - Horizontal type evaporator for nonazeotropic mixture refrigerant - Google Patents

Abstract

PURPOSE: To facilitate the surface control of a mixture refrigerant, to facilitate the production of an evaporator, and to prevent the change of the mixture refrigerant constituent ratio of a refrigerant inlet to a refrigerant outlet, by providing headers with partition walls whereby the flowing direction of a fluid to be refrigerated in a plurality of tubes passing through a shell is reversed against the flowing direction of the mixture refrigerant. CONSTITUTION: A space in a shell 11 is divided into a plurality of small spaces, both end faces of each of the small spaces are the end faces of the shell 11, and the volume of the small space at the upper side is formed larger than that of the small space at the lower side. Opening parts 17 through which the small spaces neighboring with each other communicate are formed on either side of the end faces. Obliquely placed plates forming a refrigerant flow way in zigzag shape, continuing from an liquid refrigerant inlet 14 at the lower part of the shell 11 to a gaseous refrigerant outlet 15 at the upper part thereof are provided. Furthermore, headers 12 having partition walls 23, 24 are formed so that the flowing direction of a fluid to be refrigerated in a plurality of tubes 13 axially passing through the shell 11 can be reversed against the flowing direction of a refrigerant in the refrigerant flow-way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-filled shell-and-tube type horizontal evaporator for non-azeotropic mixed refrigerants in which a refrigerant flows on the shell side and a fluid to be cooled flows on the tube side.

[0002]

2. Description of the Related Art Conventionally, a plurality of evaporation chambers along the flow direction of a fluid to be cooled, a supply port for a non-azeotropic mixed refrigerant in an evaporation chamber located on the most downstream side of the fluid to be cooled, and Non-azeotropic mixing provided with an outlet for the refrigerant gas in the evaporation chamber located on the upstream side, and with a refrigerant liquid communication path and a refrigerant gas communication path between the evaporators adjacent in the flow direction of the fluid to be cooled. An evaporator for a refrigerant is known (Japanese Patent Laid-Open No. 61-262568). In a refrigeration system using a non-azeotropic mixed refrigerant in which a plurality of refrigerants (single refrigerant) having different dew points and boiling points under a constant pressure are mixed, in order to improve heat transfer performance in the evaporator, the refrigerant is usually And a counterflow utilizing the temperature difference between the inlet and outlet of the fluid to be cooled (water, brine, etc.), more specifically, a one-pass counterflow heat exchanger is employed. In this specification, when the fluid flows from the inlet to the outlet, the flow direction is not changed, that is, the flow direction is kept constant for one pass, and the flow direction is changed only once, that is, the flow direction is positive, The case of changing it to the opposite is called 2 pass. The same is true for three or more passes. For example, the flow direction is forward, reverse,
The case of changing to positive is called 3 pass, and the case of changing to positive, reverse, normal, and reverse is called 4 pass.

FIG. 6 shows desirable temperature changes of the refrigerant and the fluid to be cooled at the inlet and outlet of the evaporator in the one-pass counterflow when the non-azeotropic mixed refrigerant is used. The refrigerant and the fluid to be cooled exchange heat with each other while flowing in opposite directions, and the temperature of the refrigerant increases from the inlet to the outlet, while the temperature of the fluid to be cooled decreases from the inlet to the outlet. go. Then, a constant temperature difference is maintained between the refrigerant and the fluid to be cooled at each position in the evaporator, and heat exchange is similarly performed at each position.

In this case, the refrigerant inlet (that is, the refrigerant liquid inlet)
It is preferable to make the component ratio of the refrigerant at the refrigerant outlet (refrigerant gas outlet) the same. In this respect, as the evaporator, the shell side is the cooled fluid, the tube side is the refrigerant, and before reaching the tube side outlet. A direct expansion type that completely evaporates the refrigerant is desirable. On the other hand, in order to improve the heat transfer performance, it is desirable that the shell side is a refrigerant, the tube side is a fluid to be cooled, and a liquid-filled type that does not cause the refrigerant to flow in the shell.

The conventionally known evaporator described in the above publication has both the tube type and the direct expansion type, and is a mixed refrigerant in the process of moving the refrigerant and passing through the evaporation chambers which are a plurality of cooling chambers. The composition ratio of the liquid is gradually changed from a state where the low boiling point refrigerant is large to a state where the high boiling point refrigerant is large. Specifically, each evaporation chamber is connected by a refrigerant liquid transfer pipe and a refrigerant gas transfer pipe, and by adjusting the position of each transfer pipe and the flow rate there, the refrigerant liquid, the gas component, and the respective component ratios are stepped. I changed it.

[0006]

In the above-mentioned conventional apparatus, there is a problem that the structure is too complicated and liquid level control in each evaporation chamber is required. In addition, the flow path of the fluid to be cooled has a one-pass structure, and when the fluid velocity is optimized, specifically, 1.5 to 2.5 m / sec, when the fluid velocity of the evaporator, which is a heat exchanger, is reduced. The length becomes impractical. On the other hand, in order to make the length of the evaporator practical, it is necessary to arrange a plurality of cylinders in parallel or adopt a structure in which a single cylinder is divided into a plurality of parts. If a plurality of cylinders are arranged in parallel, the device becomes large and complicated, and if a structure in which a plurality of cylinders are divided is adopted, it is impossible to control individual liquid levels. The present invention has been made to solve the above-mentioned conventional problems, and has a practical length,
An object of the present invention is to provide a horizontal evaporator for a non-azeotropic mixed refrigerant in which the liquid level of the refrigerant is easy to control, is easy to manufacture, and does not change the composition ratio of the refrigerant at the refrigerant inlet and outlet.

[0007]

In order to solve the above-mentioned problems, the present invention is for a liquid-filled shell-and-tube type non-azeotropic mixed refrigerant in which a refrigerant flows on the shell side and a fluid to be cooled flows on the tube side. In a horizontal evaporator, the space inside the shell is divided into multiple small spaces whose end faces are the end faces of this space, and the volume of the small space above is smaller than that of the small space below, and the adjacent small space An oblique plate that forms an opening that communicates with each other on either side of the both end surfaces, and forms a zigzag-shaped refrigerant flow path that is continuous from the refrigerant liquid inlet at the bottom of the shell to the refrigerant gas outlet at the top. And a header having a partition wall for making the flow direction of the cooled fluid in the plurality of tubes axially penetrating the shell opposite to the flow direction of the coolant in the coolant flow path.

[0008]

With the above configuration, the refrigerant liquid has fluidity, the refrigerant liquid moves in each of the small spaces in a substantially horizontal direction without resistance, and accumulates in the lower portion, and the refrigerant gas moves upward. However, the gas evaporated from the refrigerant liquid can be easily degassed, and liquid level control only in the final small space is sufficient.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show a horizontal evaporator 1 for a non-azeotropic mixed refrigerant according to a first embodiment of the present invention, which is a cylindrical shell 1
Headers 12 are attached to both sides of the shell 1 and a large number of tubes 13 are formed in the shell 11 so as to penetrate therethrough. In addition, in FIG. 1, a large number of tubes 13 actually appear in the lateral direction, but only one tube 13 is shown as an example for easy understanding of the drawing.

The shell 11 has a refrigerant liquid inlet 14 at the bottom,
It has a refrigerant gas outlet 15 in the upper part. Also, shell 1
A plurality of slanting plates 16 for dividing the internal space into a plurality of small spaces having both end faces as end faces, in the present embodiment, three slanting plates 16 are arranged in the inside of 1. . Further, in the small space partitioned by the oblique plate 16, the volume of the upper small space is larger than that of the lower small space. Further, an opening 17 for communicating the adjacent small spaces is formed on either side of the both end faces, and the refrigerant liquid inlet 14 at the lower part of the shell 11 to the refrigerant gas outlet 1 at the upper part is formed.
A zigzag-shaped coolant passage that is continuous up to 5 is formed.

For example, in the case of the above embodiment, four small spaces are formed, and as shown by the solid arrow in FIG.
The refrigerant flowing from the refrigerant liquid inlet 14 into the first small space moves to the right, flows into the second small space from the right end opening 17 and moves to the left, and moves from the left end opening 17 to the third. In the small space, moves to the right, flows from the opening 17 at the right end into the fourth small space, moves to the left, and exits from the refrigerant gas outlet 15. In the case of this embodiment, 4
It has a path structure. Here, the inclination angle of the oblique plate 16 is not limited, but is 30 ° with respect to the horizontal direction.
It is desirable to be between 45 °.

In the present embodiment, of the two headers 12 mounted on both sides of the shell 11, the header 12 on the left side in FIG. 1 is provided with an inlet 21 and an outlet 22 for the fluid to be cooled. Further, inside the left header 12, the tube 13 penetrating the first small space, the tube 13 penetrating the second and third small spaces, and the second and third small spaces are penetrated. Two partition walls 23 are provided to separate the tube 13 and the tube 13 penetrating the fourth small space. Further, the right header 12 is provided with a partition wall 24 that separates the tube 13 penetrating the first and second small spaces from the tube 13 penetrating the third and fourth small spaces. Then, in the shell 11, the flow direction of the refrigerant and the flow direction of the fluid to be cooled in the tube 13 are opposite to each other, and a counterflow state is established. Further, while the refrigerant moves from the lower side to the upper side as a whole, the fluid to be cooled generally moves from the upper side to the lower side as indicated by the dashed line arrow in FIG. It is designed to move. Further, each tube 13 is completely immersed in the refrigerant liquid, and is similar to a full liquid type.

In order to make the flow velocities of the fluid to be cooled in the tubes 13 the same, it is desirable that the number of the tubes 13 penetrating the small spaces be the same. Then, as described above, the openings 17 are alternately provided at the left and right ends of the skew plate 16 to form a plurality of zigzag paths,
Flow resistance is low, fluidity is obtained in the refrigerant liquid, the refrigerant liquid moves in each small space in a substantially horizontal direction without resistance and accumulates in the lower part, and the liquid level in each small space is almost uniform, Refrigerant gas accumulates in the upper part, and the gas evaporated from the refrigerant liquid can be easily degassed. FIG. 2 shows the movement of the refrigerant liquid and the refrigerant gas. As shown by the arrow A in the figure, the refrigerant liquid moves from the first small space to the fourth small space, and the refrigerant gas goes upward. It is easy to move, and also moves as shown by arrow B. By the way, the ratio of the high boiling point refrigerant increases from the first small space to the fourth small space.

Further, by using the liquid-filled type and the multi-pass counterflow as described above, the heat transfer performance is good, the flow velocity of the fluid to be cooled is optimized, and the length of the evaporator is made practical. Is able to. Further, the liquid level control of the refrigerant liquid is performed only in the final small space, in the case of the above embodiment, only the fourth small space is required, and the liquid level control is simple, so that the final space can take a large space. Therefore, so-called liquid back, which causes the refrigerant to flow out from the refrigerant gas outlet 15 in a liquid state, does not occur.

FIG. 3 shows a heat pump to which the evaporator 1 according to the first embodiment is applied, which includes a compressor 31 and a condenser 3.
2, a closed circulation channel of the refrigerant including the expansion valve 33 and the evaporator 1 is formed. The evaporator 1 is provided with a level controller 34 for controlling the liquid level of the refrigerant liquid inside the evaporator 1, for example, in a fourth small space, and the opening degree of the expansion valve 33 is adjusted according to the level of the liquid level. It is like this.
That is, the higher the liquid surface level, the larger the opening degree of the expansion valve 33. Further, the condenser 32 circulates a flow path 35 for circulating water serving as a high-temperature side heat source, and the inlet 21 and the outlet 22 of the evaporator 1 circulate water to be cooled serving as a low-temperature side heat source or brine. The flow path 36 is connected.

As is well known, the refrigerant gas compressed by the compressor 31 is sent to the condenser 32, where the refrigerant gas gives heat to the water flowing in the flow path 35 to lower the temperature and condense. To the expansion valve 33. The refrigerant that has condensed to the liquid state partially expands by flowing through the expansion valve 33 and flows into the evaporator 1, where heat is exchanged via the tube 13 as described above, and is cooled. The heat is taken from the fluid, the heat is completely evaporated, and the refrigerant gas is returned to the compressor 31. Thereafter, the same circulation as above is repeated. On the other hand, the cooled fluid cooled in the evaporator 1 is used as a cold heat source.

FIG. 4 shows a horizontal evaporator 2 for a non-azeotropic mixed refrigerant according to a second embodiment of the present invention, which is different from the evaporator 1 shown in FIGS. Except for the point that is provided, the other parts are substantially the same, and the common parts are denoted by the same reference numerals and the description thereof is omitted. Further, in detail, the high boiling point refrigerant liquid extraction port 41 is opened in the fourth small space which is the final small space in this embodiment. The evaporator 2 forcibly extracts the refrigerant liquid from the final small space in which the high-boiling-point refrigerant liquid easily accumulates, and is provided with a separate heat exchanger to completely evaporate the refrigerant liquid. It is a thing.

FIG. 5 shows a heat pump to which the evaporator 2 is applied, and portions common to the heat pump shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In this heat pump, a suction liquid gas heat exchanger 51 is provided between the condenser 32 and the expansion valve 33, while a refrigerant gas flowing out of the refrigerant gas outlet 15 of the evaporator 2 is guided to the suction liquid gas heat exchanger 51. A passage 52 and a passage 53 communicating with this passage and extending from the suction liquid gas heat exchanger 51 to the suction port of the compressor 31 are provided. Further, a flow path 54 connected to the high boiling point refrigerant liquid extraction port 41 is joined to the flow path 52.

Then, the refrigerant gas from the evaporator 2 and the high boiling point are mixed and led to the suction liquid gas heat exchanger 51, where heat is exchanged with the high pressure refrigerant liquid from the condenser 32. The high boiling point refrigerant liquid from the refrigerant liquid extraction port 41 is completely evaporated and sent to the compressor 31. The suction liquid gas heat exchanger 51 is provided with a level controller 55 inside which controls the liquid level of the refrigerant liquid from the high boiling point refrigerant liquid extraction port 41, and expands according to the level of the liquid level. The opening degree of the valve 33 is adjusted. That is, the higher the liquid surface level, the larger the opening degree of the expansion valve 33. In this way, by introducing the high boiling point refrigerant liquid to the suction liquid gas heat exchanger 51, the refrigerant liquid is made to flow, the heat transfer performance is further improved, and the high boiling point refrigerant liquid is completely gasified. . With such a configuration, the component ratio of the refrigerant is kept the same as the inlet of the evaporator 2, the temperature at the refrigerant liquid inlet 14 of the evaporator 2 is lowered, and the amount of heat exchanged in the evaporator 2 is increased. This will improve the coefficient of performance.

[0020]

As is apparent from the above description, according to the present invention, a liquid-filled shell-and-tube type horizontal type for non-azeotropic mixed refrigerant in which a refrigerant flows on the shell side and a fluid to be cooled flows on the tube side. In the evaporator, the space inside the shell is divided into a plurality of small spaces whose end faces are the end faces of this space, and the volume of the small space above is smaller than that of the lower space. An opening that communicates with each other is formed on either side of the both end surfaces, and a skewed plate that forms a zigzag-shaped refrigerant flow path that is continuous from the refrigerant liquid inlet at the lower portion of the shell to the refrigerant gas outlet at the upper portion, A header having a partition wall is provided to make the flow direction of the fluid to be cooled in a plurality of tubes axially penetrating the shell opposite to the flow direction of the coolant in the coolant flow passage.

As described above, by alternately providing the openings on one side of the skew plate to form a plurality of zigzag paths, the flow resistance is small, and the refrigerant liquid has fluidity. The refrigerant liquid moves almost horizontally in each small space without resistance and accumulates in the lower part, and the liquid level in each small space is almost uniformized, and the refrigerant gas accumulates upward and gas of the gas evaporated from the refrigerant liquid. Easy to remove. Further, by using the liquid-filled type and the multi-pass counterflow as described above, the heat transfer performance is good, the flow velocity of the fluid to be cooled is optimized, and the length of the evaporator can be made practical. In addition, the liquid level of the refrigerant liquid can be controlled only in the final small space, and the liquid level control is easy.
This final space can take a large space, and has the effect of allowing the refrigerant to flow out from the refrigerant gas outlet in a liquid state, serving as a so-called liquid bag, and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a horizontal evaporator for a non-azeotropic mixed refrigerant according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the evaporator shown in FIG. 1 taken along the line II-II.

FIG. 3 is a diagram showing a device configuration of a heat pump to which the evaporator shown in FIGS. 1 and 2 is applied.

FIG. 4 is a sectional view of a horizontal evaporator for a non-azeotropic mixed refrigerant according to a second embodiment of the present invention.

5 is a diagram showing a device configuration of a heat pump to which the evaporator shown in FIG. 4 is applied.

FIG. 6 is a diagram showing a desirable temperature change in a counterflow evaporator when a non-azeotropic mixed refrigerant is used.

[Explanation of symbols]

1, 2 Evaporator 11 Shell 12 Header 13 Tube 14 Refrigerant liquid inlet 15 Refrigerant gas outlet 16 Oblique plate 17 Opening

Claims (1)

[Claims] 1. A horizontal evaporator for a non-azeotropic mixed refrigerant of a liquid-filled shell-and-tube type, in which a coolant is flown to the shell side and a fluid to be cooled is flown to the tube side, the space inside the shell is defined by Is divided into a plurality of small spaces each having an end surface, and the volume of the small space above is made larger than that of the lower small space, and an opening for communicating adjacent small spaces with each other is provided on either side of the both end faces. A slanting plate that forms a continuous zigzag-shaped refrigerant flow path from the refrigerant liquid inlet at the lower part of the shell to the refrigerant gas outlet at the upper part, and the above in a plurality of tubes that axially penetrate the shell. A horizontal evaporator for non-azeotropic mixed refrigerant, comprising: a header having a partition wall which makes a flow direction of a cooled fluid to be opposite to a flow direction of a refrigerant in the refrigerant flow path.