Condenser

Abstract

To properly and surely exhibit a receiver function even when the total amount of a refrigerant filled in a refrigerating cycle is reduced to reduce the amount of a liquid refrigerant stored in a lower header, in a condenser comprising a microchannel type heat exchanger.SOLUTION: The condenser of the microchannel heat exchanger includes an upper header 26 and a lower header 27 which are formed of straight hollow tubular bodies and are arranged vertically, a large number of tubes 28 which are provided so as to connect the upper and lower headers 26 and 27 to each other and radiate heat of the refrigerant to condense the refrigerant, a delivery port 39 of the liquid refrigerant which is opened on one pipe end side of the lower header 27, and a refrigerant outlet pipe 31 which is connected to the delivery port 39 and delivers the liquid refrigerant to the downstream side. When the pipe end of the lower header 27 in which the delivery port 39 is opened is defined as an outlet end, the lower header 27 is in an inclined posture in which the outlet end side is located downward.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a condenser that constitutes a refrigeration cycle, and more particularly to a condenser that is made up of a microchannel heat exchanger. [Background technology]

[0002] In a condenser consisting of a finned tube heat exchanger, a receiver is provided between the condenser and the expansion section downstream. This receiver temporarily stores the liquid refrigerant liquefied in the condenser, separates the gaseous refrigerant, and sends only the liquid refrigerant toward the expansion section. On the other hand, some condensers consisting of a microchannel heat exchanger are endowed with the receiver function themselves (see, for example, Patent Document 1). In such a microchannel heat exchanger condenser, eliminating the receiver can be expected to simplify the configuration. Furthermore, since the liquid refrigerant stored in the receiver is no longer necessary, the total amount of refrigerant charged into the refrigeration cycle can also be reduced.

[0003] The condenser in Patent Document 1 includes a pair of parallel-arranged upper and lower headers, a heat transfer tube, and other components. Both headers are made of straight, hollow tubes, and both headers have horizontal central axes. The lower header has a larger volume than the upper header, and a downward-facing refrigerant outlet port is provided near the left end of the bottom of the lower header. The outlet port is connected to a refrigerant outlet pipe. This microchannel heat exchanger condenser temporarily stores liquid refrigerant condensed in the tubes and flowing into the lower header, allowing the condenser to function as a receiver. When functioning normally as a receiver, the liquid refrigerant and gaseous refrigerant are separated in the lower header, and only the liquid refrigerant flows out through the outlet port into the refrigerant outlet pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-26539 Summary of the Invention [Problem to be solved by the invention]

[0005] Reducing the total amount of refrigerant filled in the refrigeration cycle and reducing the proportion of liquid refrigerant relative to the internal volume of the condenser can suppress the increase in internal pressure of the condenser when the refrigeration cycle switches from a low-load operating state to a high-load operating state, thereby minimizing damage to the condenser. In other words, when the refrigeration cycle switches from a low-load operating state to a high-load operating state, a large amount of gaseous refrigerant is delivered to the condenser from the compressor. However, if the proportion of liquid refrigerant relative to the internal volume of the condenser is relatively small (if the proportion of gaseous refrigerant is relatively large), the gaseous refrigerant contracts during the load change, preventing a sudden increase in internal pressure of the condenser. Furthermore, reducing the amount of refrigerant is expected to reduce the cost of the refrigeration cycle.

[0006] However, in the condenser of Patent Document 1, if the total amount of refrigerant charged in the refrigeration cycle is reduced to suppress the amount of liquid refrigerant stored inside the lower header, the condenser's receiver function may be lost. This is because, in order for the condenser of Patent Document 1 to exhibit its receiver function, in other words, to allow only liquid refrigerant to flow out from the refrigerant outlet pipe, it is necessary to constantly store liquid refrigerant inside the lower header regardless of the operating state of the refrigeration cycle. Specifically, it is necessary to constantly keep the delivery outlet of the lower header, which communicates with the refrigerant outlet pipe, submerged in the liquid refrigerant stored inside the lower header. However, in Patent Document 1, the lower header is installed in a horizontal position, and the liquid level of the liquid refrigerant stored inside it from the bottom of the pipe is constant in the direction of the central axis of the header. Therefore, as described above, if the delivery outlet is submerged in the liquid refrigerant, a large amount of liquid refrigerant that does not contribute to submerging the delivery outlet will be stored inside the lower header. As described above, in the condenser of Patent Document 1, if the total amount of refrigerant filled into the refrigeration cycle is reduced and the amount of liquid refrigerant stored inside the lower header is reduced in order to reduce costs or reduce damage to the condenser during load fluctuations, the delivery port will no longer be submerged in the liquid refrigerant, and the condenser may lose its receiver function.

[0007] An object of the present invention is to provide a condenser consisting of a microchannel heat exchanger, in which the receiver function is properly and reliably exhibited even when the total amount of refrigerant filled in the refrigeration cycle is reduced and the amount of liquid refrigerant stored inside the lower header is reduced. [Means for solving the problem]

[0008] The present invention relates to a condenser comprising a microchannel heat exchanger. The condenser of the present invention comprises an upper header 26 and a lower header 27 formed of straight hollow pipes and arranged above and below each other, a plurality of tubes 28 connecting the upper and lower headers 26 and 27 and dissipating heat from the refrigerant to condense it, a liquid refrigerant outlet 39 opened at one pipe end of the lower header 27, and a refrigerant outlet pipe 31 connected to the outlet 39 and sending the liquid refrigerant downstream. When the pipe end of the lower header 27 where the outlet 39 is opened is defined as the outlet end, the lower header 27 is inclined so that the outlet end is positioned downward.

[0009] The lower header 27 includes a cylindrical lower header body 37 and a pair of lower plugs 38, 38 that close the pipe end openings of the lower header body 37. A delivery outlet 39 is opened in the lower plug 38 on the outlet end side. The opening center C of the delivery outlet 39 is located below the central axis L2 of the lower header 27.

[0010] A delivery port 39 is formed in a pipe bottom wall 41 of the lower header body 37 .

[0011] The upper header 26 is inclined so that its central axis L1 is parallel to the central axis L2 of the lower header 27, and each tube 28 connecting the two headers 26 and 27 is arranged perpendicular to each header 26 and 27. [Effects of the Invention]

[0012] When the pipe end of the lower header 27 where the discharge port 39 is formed is defined as the outlet end, if the lower header 27 is in an inclined position with the outlet end positioned downward, as in the condenser of the present invention, the liquid level of the liquid refrigerant stored in the lower header 27 from the pipe bottom is deep at the outlet end and becomes shallower as the distance from the outlet end increases. In addition, in the present invention, as described above, the pipe end of the lower header 27 where the discharge port 39 is formed is defined as the outlet end, and the lower header 27 is in an inclined position with the outlet end positioned downward, so that the discharge port 39 is located at the position (outlet end side) where the liquid level in the lower header 27 is deepest. As described above, according to the present invention, even when the amount of liquid refrigerant stored in the lower header 27 becomes small, the discharge port 39 can be more reliably submerged in the liquid refrigerant. In addition, according to the present invention, even if the total amount of refrigerant filled in the refrigeration cycle is reduced and the amount of liquid refrigerant stored inside the lower header 27 is reduced, the outlet 39 can be reliably submerged in the liquid refrigerant, making it possible to discharge only liquid refrigerant from the outlet 39, and allowing the receiver function to be properly and reliably performed.

[0013] Reducing the total amount of refrigerant charged into the refrigeration cycle and reducing the amount of liquid refrigerant stored inside the lower header 27 suppresses the increase in internal pressure of the condenser 12 when the refrigeration cycle changes from a low-load operating state to a high-load operating state, thereby reducing damage to the compressor 11 and the condenser 12 during the load change. Because the total amount of refrigerant charged into the refrigeration cycle can be reduced, the cost of the refrigeration cycle can be reduced.

[0014] When the opening center C of the delivery port 39 that opens on the inner surface of the lower plug body 38 on the outlet end side of the lower header 27 is located below the central axis L2 of the lower header 27, the delivery port 39 can be provided closer to the pipe bottom of the lower header 27 than when the opening center C is located at the same position as the central axis L2 or above the central axis L2. Therefore, the delivery port 39 can be reliably submerged in the liquid refrigerant stored in the lower header 27.

[0015] When the discharge outlet 39 is opened in the pipe bottom wall 41 of the lower header 27, the discharge outlet 39 can be provided in the bottom wall at the position where the liquid level is deepest, so that the discharge outlet 39 can be reliably submerged in the liquid refrigerant stored in the lower header 27.

[0016] If the upper and lower headers 26, 27 are arranged with their central axes L1, L2 parallel to each other and the tubes 28 connecting the headers 26, 27 are arranged perpendicular to the headers 26, 27, the distance between the central axes L1, L2 of the upper and lower headers 26, 27 is constant, and the length of each tube 28 can be made the same. For example, if the central axes of the upper and lower headers are arranged non-parallel, the distance between the central axes of the upper and lower headers is not constant, and multiple types of tubes with different lengths must be prepared to connect the two headers. However, if the length of each tube 28 can be made the same, as in the present invention, multiple tubes 28 can be made into a common part, thereby reducing the manufacturing cost of the condenser 12. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view showing a condenser according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional side view showing the entirety of a refrigerator to which the condenser is applied. [Figure 3] 1A and 1B are longitudinal sectional front views showing the main parts of a condenser, where FIG. 1A shows the condenser of the present invention, and FIG. 1B shows a comparative condenser with its central axis horizontal. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is a vertical sectional front view showing a main part of a condenser according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] (First Embodiment) Figures 1 to 4 show a first embodiment in which the condenser of the present invention is applied to a refrigerated open showcase, which is a refrigerator. In this embodiment, the terms front, back, left, right, and up and down refer to the crossed arrows shown in Figures 1 and 2 and the symbols near each arrow. In Figure 2, the refrigerated open showcase comprises a case body 1 made of an insulated box with an opening on the front, and a base 2 that opens forward and supports the underside of the case body 1. The interior enclosed by the case body 1 is divided into a display chamber 4 and a circulation passage 5 by an inner case 3 that is U-shaped in side view. The display chamber 4, which opens forward, has display shelves 6 arranged in multiple vertical rows for placing products such as food and beverages to be displayed. The display chamber 4 is cooled by a cooling mechanism 7 installed in the refrigerated open showcase.

[0019] As shown in Figure 2, the cooling mechanism 7 includes a compressor 11 that compresses a gaseous refrigerant, a condenser 12 that liquefies the high-pressure gaseous refrigerant discharged from the compressor 11, an expansion section (not shown) that adiabatically expands the high-pressure liquid refrigerant discharged from the condenser 12 to reduce its pressure, and an evaporator 13 that evaporates the low-pressure liquid refrigerant discharged from the expansion section at a low temperature. The compressor 11, condenser 12, expansion section, and evaporator 13 are connected in this order by connecting pipes to form a refrigeration cycle. The compressor 11, condenser 12, expansion section, and other components that make up the cooling mechanism 7 are installed on a unit base 10 that is a horizontal base plate.

[0020] The base 2 is hollow, and its interior serves as a machine room in which the devices that make up the refrigeration mechanism 7 are installed. The front opening of the base 2 is closed by a detachable machine room panel 18, which has a group of air intakes for drawing air into the base 2. The underside of the base 2 is partitioned by a unit base 10, and a compressor 11 that makes up the refrigeration cycle is disposed in the center of the unit base 10, and a condenser 12 is disposed at the front end of the base 10. A cooling fan 19 is provided between the compressor 11 and the condenser 12 to cool them both (the compressor 11 and the condenser 12), and the cooling fan 19 is fixed to the unit base 10 and attached to an air channel 20 that covers the top, left and right sides, and rear of the condenser 12.

[0021] The circulation passage 5 is U-shaped in side view, surrounding the display chamber 4 on three sides. The evaporator 13, which constitutes the cooling cycle, is disposed in the vertical circulation passage 5 defined behind the display chamber 4. A downward-facing air outlet 21 is provided at the upper front end of the circulation passage 5, and an upward-facing air inlet 22 is provided at the lower front end of the circulation passage 5. A circulation fan 23 that delivers internal air toward the evaporator 13 is provided in the horizontal circulation passage 5 defined below the display chamber 4 (upstream of the evaporator 13). When the circulation fan 23 is driven, cold air cooled by the evaporator 13 is blown downward from the air outlet 21 to the air inlet 22, forming an air curtain of cold air in front of the display chamber 4. This air curtain prevents outside air from entering the display chamber 4. The air in the display chamber 4 is also cooled.

[0022] As shown in Figure 1, the condenser 12 is an aluminum microchannel heat exchanger that includes an upper header 26 and a lower header 27 arranged vertically, a number of tubes 28 arranged in parallel in the left-right direction to connect the upper and lower headers 26 and 27, and heat-dissipating fins 29 fixed between adjacent tubes 28. The upper and lower headers 26 and 27 are formed of straight hollow tubes with their central axes L1 and L2 arranged parallel to each other. Each tube 28 is formed as a flat plate with a small wall thickness in the left-right direction and is joined to the headers 26 and 27 at right angles.

[0023] A refrigerant inlet pipe 30 constituting the connecting pipe connecting the compressor 11 and the condenser 12 is connected to the right end of the upper header 26, and a refrigerant outlet pipe 31 constituting the connecting pipe connecting the condenser 12 and the expansion section is connected to the left end of the lower header 27. A number of channels 32 serving as refrigerant flow paths communicating with the upper and lower headers 26 and 27 are formed in parallel in the front and rear inside each tube 28 (see FIG. 4), and the gaseous refrigerant that flows into the upper header 26 is condensed by heat dissipation as it passes through the channels 32, becoming liquid refrigerant. The liquid refrigerant flows into the lower header 27 and is stored therein. Each fin 29 is formed in a wave-like curve when viewed from the front in order to increase its surface area and improve cooling efficiency.

[0024] The upper header 26 is formed into a hollow, circular tube shape by a cylindrical upper header body 35 and upper plugs 36 that close the left and right tube end openings of the upper header body 35. The refrigerant inlet pipe 30 is connected to the right-side upper plug 36. Similarly, the lower header 27 is formed into a hollow, circular tube shape by a cylindrical lower header body 37 and lower plugs 38 that close the left and right tube end openings of the lower header body 37. The upper and lower header bodies 35 and 37 are formed into the same cylinder, and the upper and lower plugs 36 and 38 are formed into disks whose outer diameters match the inner diameters of the cylinders. Note that the cylinders that make up the upper and lower header bodies 35 and 37 may have different diameters.

[0025] As shown in FIG. 3(a), a refrigerant outlet port 39 is formed in the left lower plug body 38, and a refrigerant outlet pipe 31 is connected to this outlet port 39. When the pipe end of the lower header 27 on the side where the refrigerant outlet pipe 31 is disposed is defined as the outlet end, in this embodiment, the left pipe end is the outlet end. In addition, in this embodiment, the outlet port 39 is formed in the side wall inner surface 40 on the outlet end side (the inner surface of the left lower plug body 38). As shown in FIG. 4, the opening center C of the outlet port 39 is located below the central axis L2 of the lower header 27, and the outlet port 39 is provided eccentrically toward the pipe bottom wall 41 of the lower header 27 (close to the pipe bottom wall 41).

[0026] As shown in Figure 1, a pair of left and right lower supports 43 that support the lower header 27 are provided between the lower header 27 and the unit base 10. In addition, an upper support 44 that supports the upper header 26 is provided between the upper header 26 and the upper wall 45 of the air tunnel 20. As described above, the condenser 12 is fixed to the upper surface of the unit base 10 by the upper and lower supports 43 and 44. The upper support 44 is made of an irregular-shaped square block with different height dimensions on the left and right, and is disposed in the center of the upper header 26 on the left and right.

[0027] The lower support 43 is composed of a left-side lower support 43a disposed to the left of the lower header 27 and a right-side lower support 43b disposed to the right of the lower header 27. Each of the lower supports 43a and 43b is formed of an irregularly shaped rectangular block with different height dimensions. The relative height of the lower supports 43a and 43b is such that the left-side lower support 43a is smaller and the right-side lower support 43b is larger. The condenser 12, which is fixed to the upper surface of the unit base 10 by these lower supports 43a and 43b with different relative height dimensions, is fixed to the unit base 10 in a state in which the entire condenser 12 is tilted counterclockwise (leftward) from a horizontal position when viewed from the front. That is, the condenser 12 is in an inclined position with its outlet end (left end) positioned downward. The lower header 27 is also in an inclined position with its outlet end (left end) positioned downward.

[0028] 3(a) and 3(b) are diagrams illustrating the state of liquid refrigerant stored in the lower header 27. FIG. 3(a) shows a state in which the outlet end (left end) of the lower header 27 is in an inclined position (the state of this embodiment) downward, and FIG. 3(b) shows a state in which the lower header 27 is in a horizontal position. The condensers 12 in FIGS. 3(a) and 3(b) have the same structure. Both FIGS. 3(a) and 3(b) show a state in which the liquid refrigerant level is at the upper edge of the discharge port 39. As shown in FIG. 3(b), when the lower header 27 is horizontally disposed, the liquid refrigerant level stored inside the lower header 27 is constant across the left-right direction of the lower header 27. On the other hand, when the lower header 27 is in an inclined position with its left end (outlet end) downward as shown in FIG. 3(a), the liquid refrigerant is unevenly stored at the left end of the lower header 27, and the liquid refrigerant level is deeper on the left side and gradually shallower toward the right.

[0029] As described above, in the condenser of this embodiment, when the pipe end of the lower header 27 where the discharge port 39 is formed is defined as the outlet end, the lower header 27 is inclined with the outlet end positioned downward, so that the liquid level of the liquid refrigerant stored in the lower header 27 from the pipe bottom is deep at the outlet end and becomes shallower as the distance from the outlet end increases, as shown in FIG. 3( a). In addition, in this embodiment, as described above, the pipe end of the lower header 27 where the discharge port 39 is formed is defined as the outlet end, and the lower header 27 is inclined with the outlet end positioned downward, so that the discharge port 39 is located at a position where the liquid level in the lower header 27 is deepest. As described above, according to this embodiment, even when the amount of liquid refrigerant stored in the lower header 27 becomes small, the discharge port 39 can be more reliably submerged in the liquid refrigerant. In addition, according to this embodiment, even if the total amount of refrigerant filled in the refrigeration cycle is reduced and the amount of liquid refrigerant stored inside the lower header 27 is reduced, the outlet 39 can be reliably submerged in the liquid refrigerant, making it possible to discharge only the liquid refrigerant from the outlet 39, and allowing the receiver function of the condenser 12 consisting of a microchannel heat exchanger to be properly and reliably performed.

[0030] Since the total amount of refrigerant filled in the refrigeration cycle can be reduced without impairing the receiver function, and the amount of liquid refrigerant stored inside the lower header 27 can be reduced, it is expected that damage to the compressor 11 and the condenser 12 during load fluctuations will be reduced, which is due to the reduction in the amount of liquid refrigerant stored inside the lower header 27. Reducing the total amount of refrigerant also reduces the cost of the refrigeration cycle.

[0031] Since the opening center C of the delivery port 39 that opens on the inner surface of the lower plug body 38 on the outlet end side of the lower header 27 is positioned below the central axis L2 of the lower header 27, the delivery port 39 can be provided closer to the pipe bottom of the lower header 27 than when the opening center C is positioned at the same position as the central axis L2 or above the central axis L2. Therefore, the delivery port 39 can be reliably submerged in the liquid refrigerant stored in the lower header 27.

[0032] The upper and lower headers 26, 27 are arranged so that their central axes L1, L2 are parallel, and the tubes 28 connecting the headers 26, 27 are perpendicular to the headers 26, 27. This allows the distance between the central axes L1, L2 of the upper and lower headers 26, 27 to be constant, and the length of each tube 28 to be the same. Therefore, for example, if the central axes of the upper and lower headers are arranged non-parallel, the distance between the central axes of the upper and lower headers is not constant, and therefore multiple types of tubes with different lengths must be prepared to connect the headers. However, if the length of each tube 28 can be made the same, as in this embodiment, a large number of the tubes 28 can be made into a common component, thereby reducing the manufacturing cost of the condenser 12.

[0033] (Second Embodiment) Figure 5 shows a second embodiment in which the condenser of the present invention is applied to a refrigerated open showcase, which is a cooling cabinet. In this embodiment, the location where the delivery outlet 39 is formed differs from the first embodiment. The delivery outlet 39 is opened in the pipe bottom wall 41 on the outlet end side of the lower header 27. More specifically, the delivery outlet 39 is opened in the pipe bottom wall 41 of the lower header body 37 at a position close to the lower plug body 38 on the outlet end side. Furthermore, in this embodiment, the distance between the side wall inner surface 40 on the outlet end side and the left edge of the delivery outlet 39 is set to be the radius dimension of the delivery outlet 39. Since the rest is the same as the first embodiment, the same configurations, structures, and members are assigned the same reference numerals and their description will be omitted.

[0034] In this embodiment, when the delivery port 39 is provided in the pipe bottom wall 41 of the lower header 27, coupled with the inclined posture of the lower header 27, the delivery port 39 can be disposed at a position where the liquid level of the liquid refrigerant stored in the lower header 27 is at its deepest. Therefore, the delivery port 39 can be reliably submerged in the liquid refrigerant.

[0035] In addition to the above, the upper header body 35 and the lower header body 37 are not limited to cylindrical bodies, but may be polygonal cylinders such as square cylinders. [Explanation of symbols]

[0036] 12 Condenser 26 Upper header 27 Lower Header 28 tubes 31 Refrigerant outlet pipe 37 Lower header body 38 Lower plug 39 Outlet 41 Pipe bottom wall C Center of outlet opening L1 Center axis of upper header L2 Center axis of lower header

Claims

1. A condenser comprising a microchannel heat exchanger, The refrigerant condenser includes an upper header (26) and a lower header (27) formed of straight hollow pipes and arranged one above the other, a number of tubes (28) provided to connect the upper and lower headers (26, 27) and dissipating heat of the refrigerant to condense it, a liquid refrigerant outlet (39) opened at one pipe end of the lower header (27), and a refrigerant outlet pipe (31) connected to the outlet (39) and sending the liquid refrigerant downstream, This condenser is characterized in that, when the pipe end of the lower header (27) where the delivery port (39) is opened is defined as the outlet end, the lower header (27) is in an inclined position with the outlet end side positioned downward.

2. The lower header (27) includes a cylindrical lower header body (37) and a pair of lower plug bodies (38, 38) that close the pipe end openings of the lower header body (37). A delivery port (39) is opened in the lower plug body (38) on the outlet end side, 2. The condenser according to claim 1, wherein the opening center (C) of the delivery port (39) is located below the central axis (L2) of the lower header (27).

3. 2. A condenser according to claim 1, wherein a delivery port (39) is provided in a bottom wall (41) of the tube of the lower header (27).

4. The upper header (26) is inclined so that its central axis (L1) is parallel to the central axis (L2) of the lower header (27), 4. A condenser according to claim 1, wherein the tubes (28) connecting the headers (26, 27) are provided perpendicular to the headers (26, 27).

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