TWI721326B - Heat exchanger for refrigerating device and refrigerating device - Google Patents

Abstract

The problem of the present invention is to provide a heat exchanger for a refrigerating device that can extend the interval between required defrosting operations without reducing the cooling capacity. In order to solve the above-mentioned problems, the present invention provides a heat exchanger for refrigeration equipment, including: a first heat exchanger (3A) having a first refrigerant piping line; and a second heat exchanger (3B) having a series connection to the second heat exchanger 1 The second refrigerant piping line on the refrigerant piping line is arranged in parallel with the first heat exchanger (3A); a plurality of fins (3f) spanning the piping (3cA) connected to the first refrigerant piping line and the first 2 On the piping (3cB) of the refrigerant piping line; and, the blower (FM1), which blows air to the first heat exchanger (3A) and the second heat exchanger (3B). A plurality of radiating fins (3f) are arranged in parallel and facing each other in parallel, and the piping (3cA) of the first refrigerant piping line and the piping (3cB) of the second refrigerant piping line are connected so as to penetrate through the plurality of radiating fins orthogonally. The first heat exchanger (3A) and the second heat exchanger (3B) are arranged side by side so that the first heat exchanger (3A) becomes the upstream side of the blowing air.

Description

Heat exchanger for refrigerating device and refrigerating device

The present invention relates to a heat exchanger for a refrigerating device and a refrigerating device, and more particularly to a refrigerating device capable of selectively performing a cooling operation and a temperature increasing operation, and a heat exchanger for the refrigerating device used in the refrigerating device.

As a refrigerated car for distributing goods to convenience stores, etc., a refrigerated car equipped with the following refrigerating device has been put into practical use. The refrigerating device can maintain the goods loaded in the warehouse at the optimal temperature without being affected by the outdoor temperature. Therefore, not only can the inside of the library be cooled, but also can be raised. According to this refrigerating device, when the outdoor temperature is higher than the maintenance temperature, it is mainly cooled in summer, and when the outdoor temperature is lower than the maintenance temperature, it is mainly heated in winter. Patent Document 1 describes an example of such a refrigerating device as a refrigerating device for land transportation. The refrigeration device for land transportation described in Patent Document 1 is a heat pump type.

In general, if a refrigerated vehicle is driving during snowfall, the external heat exchanger may not function as a heat exchanger for heating operation due to the adhesion of the blown snow. At this time, a defrost operation is performed to melt the attached snow. However, if the defrosting action is frequently performed, that is, if the interval between the defrosting actions is shortened, the efficiency of the temperature-raising action will decrease. Therefore, the refrigerating apparatus for land transportation described in Patent Document 1 has a structure that prevents the execution interval of the defrosting operation from shortening during the operation of the temperature-raising mode while the refrigerating vehicle is driving during snowfall. Specifically, it includes: an air duct that guides the exhaust air from the engine of the refrigerated vehicle to the suction side of the external heat exchanger; a means for opening and closing the air passage in the air duct; and a panel (Panel) that covers the warehouse The form of the external heat exchanger is arranged in front of the suction side of the external heat exchanger.

For example, according to the panel, snow will not be blown directly into the external heat exchanger. In this way, since snow accumulation is suppressed and the function as a heat exchanger is maintained, it is no longer necessary to shorten the defrosting operation interval.

[Prior Art Document] (Patent Document) Patent Document 1: Japanese Patent Application Laid-Open No. 2010-255909.

[Problems to be Solved by the Invention] However, in the refrigerating device described in Patent Document 1, since the panel is arranged in front of the suction side of the external heat exchanger so as to cover the external heat exchanger, the refrigerated vehicle runs When the driving wind (wind generated by the vehicle traveling, based on the relative speed of the vehicle and the air) is blocked by the panel, it cannot be directly blown to the external heat exchanger. Therefore, in the cooling operation in which the external heat exchanger functions as a condenser, it may not be possible to ensure a sufficient air volume. If a sufficient air volume cannot be ensured, the following problems will occur: the refrigerant cannot be sufficiently condensed, and the cooling capacity is reduced. Therefore, for the heat exchanger for refrigeration equipment and the refrigeration equipment, it is desirable that the interval between the required defrosting operations can be extended without reducing the cooling capacity.

Therefore, the problem to be solved by the present invention is to provide a heat exchanger for a refrigeration device and a refrigeration device using the heat exchanger for a refrigeration device. The heat exchanger for a refrigeration device can extend without reducing the cooling capacity. The interval between the required defrost actions.

[Technical Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention has the following configuration. (1) A heat exchanger for refrigeration equipment, comprising: a first heat exchanger having a first refrigerant piping line; a second heat exchanger having a second refrigerant piping connected in series to the first refrigerant piping line Line, and arranged in parallel with the first heat exchanger; a plurality of radiating fins, which straddle both the piping connected to the first refrigerant piping line and the piping of the second refrigerant piping line; and, the blower, which is opposite The first heat exchanger and the second heat exchanger blow air; and the plurality of radiating fins are arranged in parallel and opposed to each other in parallel, and the piping of the first refrigerant piping line and the piping of the second refrigerant piping line are aligned The first heat exchanger and the second heat exchanger are connected so as to pass through the plurality of radiating fins, and the first heat exchanger and the second heat exchanger are arranged in parallel so that the first heat exchanger becomes the upstream side of the blowing air generated by the blower. (2) The heat exchanger for a refrigeration apparatus according to (1), wherein the first refrigerant piping line has two or more paths, and the number of paths is Na (Na: an integer greater than or equal to 2). (3) The heat exchanger for a refrigeration system according to (2), wherein the second refrigerant piping line has two or more paths, the number of paths is Nb (Nb: an integer greater than or equal to 2), and the number of paths Na is equal to The aforementioned number of paths Nb satisfies 2≤Na≤Nb. (4) The heat exchanger for a refrigeration device according to any one of (1) to (3), wherein at least one of the first heat exchanger and the second heat exchanger is a fin-tube heat exchanger Switch. (5) The heat exchanger for a refrigerating device according to any one of (1) to (3), wherein when used as the aforementioned external heat exchanger of a refrigerating device, the refrigerating device includes an internal heat exchanger. And the refrigerant circuit of the external heat exchanger, and selectively perform a cooling operation to cool the interior and a temperature increase operation to raise the temperature in the interior. In the cooling operation, the first heat exchanger and the second heat exchanger It functions as a condenser integrally, and in the temperature raising operation, the first heat exchanger functions as a subcooler, and the second heat exchanger functions as an evaporator. (6) The heat exchanger for a refrigerating device as described in (4), wherein when used as the aforementioned external heat exchanger of a refrigerating device, the refrigerating device includes a refrigerant including an internal heat exchanger and an external heat exchanger In the cooling operation, the first heat exchanger and the second heat exchanger function integrally as condensers, and the cooling operation to cool the interior and the temperature increase operation to raise the temperature in the interior are selectively performed. In the heating operation, the first heat exchanger functions as a subcooler, and the second heat exchanger functions as an evaporator. (7) A refrigerating device including a refrigerant circuit including an internal heat exchanger, an external heat exchanger, and a receiver capable of retaining refrigerant, and the refrigerating device selectively performs a cooling operation and a cooling system for cooling the inside of the refrigerator. A temperature-rising operation for increasing the temperature inside the refrigerator, characterized in that the external heat exchanger is the heat exchanger for the refrigerator described in (1), and in the cooling operation, the first heat exchanger and the second 2 The heat exchanger functions as a condenser integrally. In the temperature increase operation, the first heat exchanger functions as a subcooler, and the second heat exchanger functions as an evaporator. The first heat The exchanger has a piping row group. The piping row group is formed by arranging M (M: an integer greater than or equal to 1) in series in a row of piping lines of a specific capacity in the direction of the aforementioned air supply, and the aforementioned M is the aforementioned first The capacity of the heat exchanger is the maximum value that does not exceed the range of the capacity of the aforementioned liquid receiver. (8) The refrigeration system according to (7), wherein the first refrigerant piping line has two or more paths, the number of paths is Na (Na: an integer greater than or equal to 2), and the group of piping rows is the same as the two or more paths. Set the path correspondingly.

(Effects of the Invention) According to the present invention, it is possible to obtain the following effect: it is possible to extend the execution interval of the required defrosting operation without reducing the cooling capacity.

According to the external heat exchanger 3 of the embodiment, the refrigerating device 51 using the external heat exchanger 3, and their modified examples, referring to Figs. 1 to 19, the refrigerating device heat for the embodiment of the present invention will be described. Exchanger and refrigeration unit.

[Example]

The configuration of the refrigerating device 51 is shown in Fig. 1 as the refrigerant circuit diagram and Fig. 2 showing the control system. That is, the refrigerant circuit of the refrigeration device 51 has the following configuration: a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 including a fan FM1 driven by a motor, a receiver 4, and a motor driven The blower is the internal heat exchanger 5, the accumulator 6, the solenoid valve 11, and the solenoid valve 13 of the fan FM2.

The operations of the compressor 1, the four-way valve 2, the fan FM1, the fan FM2, the solenoid valve 11, and the solenoid valve 13 in the refrigerant circuit are controlled by the control unit 31. The operation instructions given by the user are transmitted to the control unit 31 via the input unit 32.

The external heat exchanger 3 and the internal heat exchanger 5 are so-called fin and tube heat exchangers. In addition, the external heat exchanger 3 has the following configuration: a first external heat exchanger 3A and a second external heat exchanger 3B; and, the first external heat exchanger 3A and the second external heat exchanger 3B A circuit connected in series on the refrigerant circuit (parallel circuit LP1). The first external heat exchanger 3A has a refrigerant piping line 3LA that connects a port (port) 3Aa and a port 3Ab (refer to FIGS. 4 and 7). In addition, the second external heat exchanger 3B has a refrigerant piping line 3LB that connects the port 3Ba and the port 3Bb (refer to FIGS. 4 and 7). The details of this external heat exchanger 3 will be described in detail below.

The refrigerant circuit of the refrigeration device 51 will be described in detail. The port 2a of the compressor 1 and the four-way valve 2 is connected by a piping line L1. The port 2b of the four-way valve 2 and the port 3Ba of the second external heat exchanger 3B in the external heat exchanger 3 are connected by a piping line L2. The port 3Bb of the second external heat exchanger 3B and the port 3Ab of the first external heat exchanger 3A are connected via the parallel circuit LP1.

The parallel circuit LP1 has the following configuration: a piping line L3 and a piping line L4. The piping line L3 is equipped with an expansion valve 7; and a check valve 8, which is connected in series to the expansion valve 7 on the side of the first external heat exchanger 3A, and is only allowed to go from the first external heat exchanger 3A The second external heat exchanger 3B circulates. The piping line L4 is provided with a check valve 9 which allows only the flow from the second external heat exchanger 3B to the first external heat exchanger 3A.

The port 3Aa of the first external heat exchanger 3A and the receiver 4 are connected by a piping line L5. On the piping line L5, a branch D1 and a branch D2 are provided in the middle. Between the branch portion D1 and the branch portion D2, a check valve 10 is arranged, and this check valve 10 allows only the flow from the first external heat exchanger 3A to the receiver 4.

The receiver 4 and the internal heat exchanger 5 are connected via a parallel circuit LP2. The parallel circuit LP2 has the following configuration: a piping line L6 and a piping line L7. The piping line L6 is provided with an electromagnetic valve 11 and an expansion valve 12 connected in series to the electromagnetic valve 11 on the side of the internal heat exchanger 5. A solenoid valve 13 is arranged on the piping line L7.

The internal heat exchanger 5 and the port 2d of the four-way valve 2 are connected by a piping line L8. On the piping line L8, a branch D3 and a branch D4 are provided in the middle. Between the branch portion D3 and the branch portion D4, a check valve 14 is arranged, and the check valve 14 only allows the flow from the internal heat exchanger 5 to the four-way valve 2.

The branch D3 in the piping line L8 and the branch D1 in the piping line L5 are connected by the piping line L9. A check valve 15 is provided on the piping line L9, and this check valve 15 allows only the flow from the branch portion D3 to the branch portion D1. The branch D4 in the piping line L8 and the branch D2 in the piping line L5 are connected by the piping line L10. A check valve 16 is provided on the piping line L10, and this check valve 16 allows only the flow from the branch portion D4 to the branch portion D2. The four branch portions and the four check valves, that is, the branch portions D1 to D4, the check valve 10, and the check valves 14 to 16, constitute the flow direction restricting portion RK. The flow direction restricting portion RK corresponds to the flow path selection performed with the switching of the four-way valve 2 and restricts the flow direction of the refrigerant that enters and exits the port 3Aa of the external heat exchanger 3. The details are described below.

The port 2c of the four-way valve 2 and the compressor 1 are connected via a piping line L11 via an accumulator 6.

For this refrigerant circuit, the control unit 31 selectively controls so that the operation of the four-way valve 2 becomes either mode A or mode B. For specific description with reference to Fig. 3, the mode A is the following mode: the port 2a and the port 2b are connected, and the port 2c and the port 2d are connected. Mode B is the following mode: connect port 2a to port 2d, and connect port 2b to port 2c. According to the four-way valve 2, in the mode A, the flow path RA is selected as the line through which the refrigerant flows (refer to the thick line in FIG. 9). Also, in the mode B, the flow path RB is selected (refer to the thick line in FIG. 10). That is, the four-way valve 2 functions as a flow path selection unit that selects a flow path through which the refrigerant flows in the refrigerant circuit. In addition, the control unit 31 controls the solenoid valve 11 and the solenoid valve 13 to alternately open them. This control is carried out in conjunction with the action of the four-way valve 2. Specifically, as shown in FIG. 3, in mode A, the solenoid valve 11 is opened and the solenoid valve 13 is closed. In mode B, the solenoid valve 11 is closed, and the solenoid valve 13 is opened.

Next, the details of the external heat exchanger 3 will be described with reference to FIGS. 4 to 7. FIG. 4 is a schematic configuration diagram corresponding to the cross section of the external heat exchanger 3. Fig. 5 is an external perspective view of the external heat exchanger 3 viewed obliquely from the lower left, and Fig. 6 is an external perspective view of the external heat exchanger 3 viewed obliquely from the lower right. FIG. 7 is a diagram for explaining the internal paths (refrigerant piping lines 3LA, 3LB) of the external heat exchanger 3. The directions of up, down, left, and right, front and back shown in Figs. 4 to 6 are directions set appropriately for easy understanding, and the installation aspect and the like are not limited.

As described above, the external heat exchanger 3 is configured in the form of a fin-tube heat exchanger. As shown in FIG. 4, the pipe 3c as a pipeline has 4 rows in the front-rear direction in the cross section, and 14 stages in each row in the up-down direction. That is, if it is a fin-tube heat exchanger with M rows and N stages, M=4 and N=14. The tubes 3c are arranged folded back at the left and right ends so as to be connected as shown by the thick lines in FIG. 4.

Among the four rows, one row on the frontmost side is included in the first external heat exchanger 3A, and three rows from the rear side are included in the second external heat exchanger 3B. That is, the first external heat exchanger 3A has 1 row and 14 stages, and the second external heat exchanger 3B has 3 rows and 14 stages. Here, one row or two or more rows connected in series are referred to as the piping row group G. In the case of one row, it is also called "piping row group" for convenience. Therefore, the first external heat exchanger 3A has a piping row group GA with M=1, and the second external heat exchanger 3B has a piping row group GB with M=3. In addition, in the first external heat exchanger 3A, the 7-stage pipe 3cA on the upper side constitutes a path P1 as one refrigerant piping line, and the 7-stage lower pipe constitutes a path P2 as a refrigerant piping line. In the second external heat exchanger 3B, a total of 14 pipes 3cB in 5 or 4 rows in each row on the upper side constitute a path P3 as a refrigerant piping line, and a total of 14 pipes 3cB in 5 or 4 rows in the center portion The root pipe 3cB constitutes the path P4 as one refrigerant piping line, and the 14 pipes 3cB in 5 or 4 steps in each row on the lower side constitutes the path P5 as one refrigerant piping line. Therefore, as shown in FIG. 4, in the first external heat exchanger 3A, the piping row group GA1 and the piping row group GA2 are provided corresponding to the path P1 and the path P2, respectively. In addition, in the second external heat exchanger 3B, piping row groups GB3 to GB5 are provided corresponding to the paths P3 to P5, respectively.

The number of paths Na of the first external heat exchanger 3A is an integer of 2 or more, and the number of paths of the second external heat exchanger Nb (Nb: an integer of 2 or more) or less. That is, 2≤Na≤Nb. The external heat exchanger 3 of the refrigeration unit 51 satisfies this relationship. As described above, the number of paths Na of the first external heat exchanger 3A is 2, and the number of paths Nb of the second external heat exchanger 3B is 3 or less.

In the first external heat exchanger 3A, the port 3Aa is branched and connected to one end of the path P1 and one end of the path P2. The port 3Ab diverges and is connected to the other end of the path P1 and the other end of the path P2. That is, as shown in FIG. 7, the path P1 and the path P2 are connected in parallel between the port 3Aa and the port 3Ab. Furthermore, as shown in FIG. 4, the path P1 and the path P2 are arranged so that they do not overlap with each other in the blowing direction (front-rear direction), and become substantially independent areas on the suction surface.

In the second external heat exchanger 3B, the ports 3Ba are branched into three, and they are respectively connected to one end of the paths P3 to P5. The ports 3Bb are divided into three, and they are respectively connected to the other end sides of the paths P3 to P5. That is, as shown in FIG. 7, the paths P3 to P5 are connected in parallel between the port 3Ba and the port 3Bb. As shown in Fig. 4, the paths P3 to P5 are arranged in such a way that they do not substantially overlap each other in the blowing direction (front-rear direction), but become substantially independent on the suction side (hereinafter also referred to as the suction surface) Area.

The smaller the number of paths Na in the first external heat exchanger 3A is, the larger the area occupied by one path on the suction surface is. Therefore, the first external heat exchanger 3A is likely to have significant surface temperature unevenness. Therefore, if the number of paths Na is increased, the area occupied by one path on the suction surface will become smaller, and the unevenness of the overall surface temperature will be suppressed. That is, from the viewpoint of suppressing unevenness in surface temperature, it is preferable to increase the number of paths Na. On the other hand, when two or more paths are provided, the greater the number of paths Na, the lower the flow velocity of the refrigerant passing through the paths. Therefore, in the design, the degree of unevenness in the surface temperature and the flow rate of the refrigerant are considered, and the number of paths Na is set so that the heat exchange function can be performed well. For example, the number of paths Na of the first external heat exchanger 3A and the number of paths Nb of the second external heat exchanger 3B can be the same number (Na=Nb), and the second external heat exchanger 3B will be described later. It functions as an evaporator during the temperature-raising operation, and it is more preferable that the number of paths Na of the first external heat exchanger 3A be equal to or less than the number of paths Nb of the second external heat exchanger 3B (Na<Nb).

Consider the length of the piping between port 3Ba and port 3Bb, the flow path area of the piping (piping inner diameter), the speed of the refrigerant flowing in the piping, etc., and appropriately set the number of paths Nb of the second external heat exchanger 3B so that It can make a good phase change of liquid refrigerant into gaseous refrigerant.

As shown in Figs. 5 and 6, a plurality of fins 3f are provided across the first external heat exchanger 3A and the second external heat exchanger 3B, respectively. In detail, the plurality of radiating fins 3f are close to each other and arranged in parallel to oppose each other in parallel. Furthermore, the piping of the refrigerant piping line of the first external heat exchanger 3A is pipe 3cA (refer to Fig. 4) and the piping of the refrigerant piping line of the second external heat exchanger 3B is pipe 3cB (refer to Fig. 4) ), which are connected to perpendicularly penetrate through the plurality of radiating fins 3f. Therefore, between the first external heat exchanger 3A and the second external heat exchanger 3B, heat is transferred to each other via the fins 3f.

The first external heat exchanger 3A and the second external heat exchanger 3B are arranged side by side in the front-rear direction. Specifically, the first external heat exchanger 3A is arranged so as to be on the windward side with respect to the flow direction of the wind generated by the driving of the fan FM1. That is, the first external heat exchanger 3A is an upstream side heat exchanger, and the second external heat exchanger 3B is a downstream side heat exchanger.

The refrigerating device 51 described in detail above can be applied to various equipment and devices, and the like. For example, it is placed in a refrigerated car C. Fig. 8 is a side view showing an example mounted on the refrigerating vehicle C, and a part of it is a cut surface.

The internal heat exchanger 5 is arranged in the internal space CV of the container C1 (hereinafter also referred to as the "library C1") that should maintain a constant temperature in the refrigerated vehicle C, and exchanges heat with the air in the internal space CV. Outside the container C1 (for example, above the driver's seat), an external heat exchanger 3 is arranged to exchange heat with outside air. The other components are installed on the outside of the container C1, and the installation location is not limited. For example, the compressor 1 and the accumulator 6 are housed in the housing S, and are installed below the vehicle body. The control unit 31 and the input unit 32 are installed near the driver's seat. In particular, the input unit 32 is arranged in a place where the driver can easily operate it. The power source of the compressor 1 is, for example, a battery or an engine of the refrigerated vehicle C (both not shown).

Next, the operation operation of the refrigerating device 51 will be described mainly with reference to Figs. 3, 7, and 9 to 11 based on the state of being mounted on the refrigerating vehicle C. The refrigerating device 51 selectively executes a plurality of modes of operation based on instructions given by the user via the input unit 32, that is, cooling operation, warming operation, defrosting operation of the external heat exchanger 3, and internal heat exchange The defrosting operation of the device 5 makes the temperature in the storage C1 constant.

First, the cooling operation and the heating operation are explained. Fig. 9 is a diagram for explaining the refrigerant circuit during the cooling operation. Fig. 10 is a diagram for explaining the refrigerant circuit during the heating operation. Fig. 11 is a table for explaining the control of the control unit 31 during each operation. In the refrigerant circuits of Figs. 9 and 10, the piping portion where the refrigerant flows is indicated by thick lines, and the direction of the refrigerant flow is indicated by thick arrows.

(Cooling operation) As shown in Figure 11, during the cooling operation, the control unit 31 sets the four-way valve 2 to mode A, the solenoid valve 11 is opened, the solenoid valve 13 is closed, and the fan FM1 and fan FM2 are in operation. . In Fig. 9, the blowing directions generated by the fan FM1 and the fan FM2 during this cooling operation are indicated by arrows DR1 and DR2, respectively.

As shown in FIG. 9, under the control of the control unit 31, the high-pressure gaseous refrigerant discharged from the discharge port of the compressor 1 flows from the port 2a of the four-way valve 2 of the mode A through the port 2b into the piping line L2. The gaseous refrigerant flowing into the piping line L2 is supplied from the port 3Ba to the second external heat exchanger 3B in the external heat exchanger 3, flows through any one of the paths P3 to P5, and then flows from the port 3Bb to the second external heat exchanger 3B. It flows out in the form of liquid mixed refrigerant. The gas-liquid mixed refrigerant flowing out from the port 3Bb passes through the check valve 9 and is supplied from the port 3Ab to the first external heat exchanger 3A, flows through any one of the path P1 and the path P2, and then flows out from the port 3Aa.

In the external heat exchanger 3, the fan FM1 is in an operating state under the control of the control unit 31, and the outside air flows in the direction of the arrow DR1 in Fig. 9. In this state, in the external heat exchanger 3, the second external heat exchanger 3B and the first external heat exchanger 3A function as an integrated condenser. That is, the gaseous refrigerant radiates heat to the outside air and condenses, and flows into the piping line L5 from the port 3Aa in the form of a high-pressure liquid refrigerant. Specifically, the refrigerant is in the gas phase at the inlet of the second external heat exchanger 3B, which is the port 3Ba. As the refrigerant in the gas phase (gas refrigerant) flows in the second external heat exchanger 3B, it exchanges heat with the outside air, part of the gas refrigerant is condensed (liquefied), and the ratio of the liquid refrigerant to the gas refrigerant increases. In this way, at the outlet of the second external heat exchanger 3B, which is the port 3Bb, the refrigerant becomes a gas-liquid mixed refrigerant in which a liquid refrigerant and a gaseous refrigerant are mixed. Here, the ratio of the liquid refrigerant varies depending on the operating conditions.

Next, the gas-liquid mixed refrigerant flowing out of the port 3Bb flows into the first external heat exchanger 3A from the port 3Ab. With the first external heat exchanger 3A, the heat exchange between the refrigerant and the outside air is continued, and in the outlet port 3Aa, the refrigerant becomes almost all in the liquid phase (liquid state) under high pressure.

Since the refrigerant undergoes a phase change from the gas phase to the liquid phase in the external heat exchanger 3, the volume of the refrigerant is reduced. In the external heat exchanger 3, the number of paths Na of the first external heat exchanger 3A through which the refrigerant with a higher liquid phase ratio circulates due to the decrease in volume is less than that of the second external heat exchanger 3A through which the refrigerant with a higher gas phase ratio circulates. The number of paths Nb of the external heat exchanger 3B. As a result, the refrigerant circulating in the first external heat exchanger 3A has a higher mass flow rate and a higher degree of subcooling of the refrigerant than when the refrigerant circulates in the second external heat exchanger 3B in the form of liquid refrigerant. Big.

The high-pressure liquid refrigerant flowing into the piping line L5 passes through the check valve 10 and enters the receiver 4. In the receiver 4, the remaining amount of liquid refrigerant corresponding to the operating environment is retained. For example, when the thermal load in the storage C1 is small, the amount of circulating refrigerant may be small, and a large amount of liquid refrigerant may be accumulated in the receiver 4. On the other hand, when the thermal load in the storage C1 is large, the amount of circulating refrigerant needs to be large, and therefore the amount of liquid refrigerant accumulated in the receiver 4 becomes small. The receiver 4 has a structure that allows the liquid refrigerant to flow out when the liquid refrigerant is accumulated.

The solenoid valve 13 is closed and the solenoid valve 11 is opened under the control of the control unit 31. Therefore, the liquid refrigerant flowing out of the receiver 4 flows into the piping line L6. That is, the liquid refrigerant flowing into the piping line L6 passes through the solenoid valve 11 and enters the expansion valve 12. In the expansion valve 12, the liquid refrigerant expands. In this way, the liquid refrigerant is reduced in pressure and temperature, and gasification is promoted, and it becomes a gas-liquid mixed refrigerant in which the gas phase and the liquid phase are mixed. The gas-liquid mixed refrigerant flowing out of the expansion valve 12 flows into the internal heat exchanger 5.

In the internal heat exchanger 5, the fan FM2 is in an operating state under the control of the control unit 31, and causes the air in the compartment C1 to flow in the direction of the arrow DR2 in FIG. 9. In this state, the gas-liquid mixed refrigerant exchanges heat with the air in the storage C1, obtains heat from the air in the storage C1, is completely vaporized, and becomes a gaseous refrigerant. That is, the internal heat exchanger 5 functions as an evaporator, so the inside of the library C1 is cooled.

The gaseous refrigerant flowing out of the internal heat exchanger 5 flows into the piping line L8. In the piping line L8, since the pressure of the gaseous refrigerant at the branch D3 is lower than the pressure at the branch D1 of the piping line L5, it does not flow into the piping line L9, but passes through the check valve 14 to the four-way valve 2. Since the four-way valve 2 becomes the mode A under the control of the control unit 31, the gaseous refrigerant flows from the port 2d through the port 2c, and further flows through the accumulator 6 and returns to the suction port of the compressor 1.

(Temperature heating operation) As shown in Figure 11, during the heating operation, the control unit 31 sets the four-way valve 2 to mode B, the solenoid valve 11 is closed, the solenoid valve 13 is opened, and the fan FM1 and fan FM2 are in operation. . The blowing direction of the fan FM1 and the fan FM2 during the heating operation is the same as the cooling operation, and is a constant direction, and is indicated by an arrow DR3 and an arrow DR4 in FIG. 10, respectively.

As shown in FIG. 10, under the control of the control unit 31, the high-pressure gaseous refrigerant discharged from the discharge port of the compressor 1 flows into the piping line L8 from the port 2a of the four-way valve 2 in the mode B through the port 2d. Next, the gaseous refrigerant flows into the piping line L10 from the branch D4 and enters the receiver 4.

In the receiver 4, the gaseous refrigerant squeezes out the liquid refrigerant accumulated in the previous cooling operation, and fills the receiver 4 quickly. Therefore, the gaseous refrigerant flows out of the receiver 4 following the accumulated amount of liquid refrigerant. According to the control of the control unit 31, the solenoid valve 13 is opened and the solenoid valve 11 is closed. Therefore, the gaseous refrigerant flowing out of the receiver 4 flows into the piping line L7, and then flows into the internal heat exchanger 5.

In the internal heat exchanger 5, as described above, the fan FM2 is in an operating state under the control of the control unit 31, and the air in the compartment C1 flows in the direction of the arrow DR4 in FIG. 10. In this state, the gaseous refrigerant exchanges heat with the air in the storage C1, releases heat to the air in the storage C1, condenses, and substantially becomes a high-pressure liquid refrigerant. Therefore, the temperature in the library C1 is increased.

The refrigerant flowing out of the internal heat exchanger 5 contains liquid refrigerant and also contains gaseous refrigerant in an amount corresponding to the operating environment such as the heat load in the storage C1. Since the pressure at the branch D3 is lower than that at the branch D4, the gas-liquid mixed refrigerant containing the liquid refrigerant and the gaseous refrigerant flows into the piping line L9. Then, it flows through the check valve 15 and flows into the first external heat exchanger 3A of the external heat exchanger 3 from the port 3Aa.

In the external heat exchanger 3, the fan FM1 is in an operating state under the control of the control unit 31, and the outside air flows in the direction of the arrow DR3 in Fig. 10. Therefore, the first external heat exchanger 3A is located on the upstream side of the flow of outside air with respect to the second external heat exchanger 3B. In this state, the liquid refrigerant is cooled in the first external heat exchanger 3A, and the temperature drops. That is, the first external heat exchanger 3A functions as a supercooling heat exchanger for the liquid refrigerant. The gaseous refrigerant flowing into the first external heat exchanger 3A together with the liquid refrigerant is cooled by this, and almost all becomes the liquid refrigerant.

The supercooled liquid refrigerant flows out of the port 3Ab of the first external heat exchanger 3A, and flows into the piping line L3. In the piping line L3, the liquid refrigerant passes through the check valve 8 and enters the expansion valve 7. In the expansion valve 7, the liquid refrigerant expands. In this way, the pressure and temperature of the liquid refrigerant are reduced, and gasification is promoted to become a gas-liquid mixed refrigerant in which a gas phase and a liquid phase are mixed. The gas-liquid mixed refrigerant flowing out of the expansion valve 7 flows into the second external heat exchanger 3B from the port 3Bb. In the second external heat exchanger 3B, the gas-liquid mixed refrigerant flowing in from the port 3Bb obtains heat from the outside air to evaporate by heat exchange with the outside air, becomes a gaseous refrigerant, and flows into the piping line L2 from the port 3Ba. That is, the second external heat exchanger 3B functions as an evaporator. The gaseous refrigerant flowing into the piping line L2 passes through the port 2b of the four-way valve 2 in the mode B, passes through the port 2c, flows through the accumulator 6 and returns to the suction port of the compressor 1.

In this heating operation, the refrigeration device 51 obtains the following effects.

The four-way valve is used to switch between the cooling operation and the heating operation. In the heating operation, not only the heat obtained by the compressor operation is used to raise the temperature, but also the heat obtained from the outside air by the external heat exchanger is used to raise the temperature. Therefore, a higher temperature raising ability is obtained.

The switching between the cooling operation and the heating operation is performed only by switching between the four-way valve and the solenoid valve, and there is no need to perform control based on the measurement result of the pressure sensor or the like. Therefore, the control of the running action is simple.

In the second external heat exchanger 3B, the gas-liquid mixed refrigerant performs heat exchange to obtain heat from the outside air, and becomes a low-pressure gas refrigerant. In the external heat exchanger 3, a plurality of fins 3f are provided so as to straddle the first external heat exchanger 3A and the second external heat exchanger 3B. Therefore, in the first external heat exchanger 3A, part of the heat released by the liquid refrigerant is transferred to the fins 3f and moved to the second external heat exchanger as a phase change in the second external heat exchanger The heat of evaporation is used. In this way, since the evaporation of the liquid refrigerant in the second external heat exchanger is promoted, it is possible to prevent the liquid refrigerant from being sucked into the compressor, which is the so-called liquid hammer (liquid return) phenomenon.

Moreover, even when the operating environment is, for example, driving in a cold area and snow accumulates on the fins 3f due to snowfall, the snow adhering to the fins 3f will be affected by the first external heat exchanger due to the fins 3f. The heat released by the heat exchange during the heating operation becomes warm and melts. In addition, the portion of each fin 3f on the side of the second external heat exchanger 3B becomes warm due to the following reasons: the outside air heated by the heat exchange in the first external heat exchanger 3A, Circulate to the downstream side; and, the heat imparted to the fin 3f by heat exchange in the first external heat exchanger 3A is transferred to the downstream side of the fin 3f. In this way, since all the heat sinks 3f are warmed efficiently, it is extremely effective to prevent snow or frost on the heat sinks 3f. Therefore, the execution interval of the defrosting operation of the refrigerating device 51 becomes longer, and the operation efficiency is improved.

During this heating operation, no liquid refrigerant remains in the receiver 4. On the other hand, in accordance with the operating environment including the heat load in the storage C1, the amount of refrigerant circulation required by the refrigerant circuit changes. Therefore, in the first external heat exchanger 3A of the refrigerating device 51, there are liquid refrigerant and gaseous refrigerant in an amount corresponding to the operating environment. In other words, the first external heat exchanger 3A replaces the receiver 4 during the warming operation to adjust and secure the remaining liquid refrigerant so that the refrigerant circuit circulates the refrigerant amount that is most suitable for the operating environment. In this way, the pressure on the high-pressure side of the refrigerant circuit can be maintained at a high value. Therefore, the condensation temperature of the refrigerant in the internal heat exchanger 5 becomes higher, and the temperature raising ability improves.

The refrigerating device 51 uses the flow direction restricting portion RK or the like to make the direction of the refrigerant flowing in the indoor heat exchanger 5 the same during the cooling operation and the temperature raising operation. In addition, the direction of the airflow generated by the operation of the fan FM2 is also the same in the cooling operation and the heating operation. Also, as shown in Figures 9 and 10, the flow direction of the refrigerant in the internal heat exchanger 5 may be such that it faces the blowing direction (arrows DR2 and DR4) from the downstream side to the upstream side (from the Inflow from the downstream side and outflow from the upstream side). Due to the above and other reasons, there is no significant difference between the heat exchange efficiency during the cooling operation and the heat exchange efficiency during the heating operation. In this way, the heat exchange efficiency is further improved.

In the cooling operation and the heating operation, the amount of refrigerant enclosed in the refrigerant circuit is the same. That is, since the liquid refrigerant is not stored in the receiver 4 during the heating operation, the liquid refrigerant remaining in the receiver 4 during the cooling operation is transferred to the first external heat exchanger 3A during the heating operation. Internally adjust and ensure the amount of liquid refrigerant. Specifically, the secured amount of liquid refrigerant in the first external heat exchanger 3A is adjusted by changing the vaporization amount of the liquid refrigerant (amount of gaseous refrigerant). Regarding the adjustment function of the amount of liquid refrigerant in the first external heat exchanger 3A, based on experiments, the following conclusions have been obtained: It is more desirable to set the liquid refrigerant capacity Qa of the first external heat exchanger 3A to not A value exceeding the capacity Qb of the liquid refrigerant of the receiver 4 (that is, Qa≦Qb). The adjustment setting of this capacity Qa is performed by, for example, increasing or decreasing the number of rows of tubes 3c in the first external heat exchanger 3A. That is, the first external heat exchanger 3A of the M row and the N stage is formed by setting one of the rows into a fixed structure with a specific capacity, and setting M of this fixed structure in parallel along the blowing direction of the fan FM1. At this time, it is preferable to set the value of M to the maximum value in a range in which the capacity of the first external heat exchanger 3A does not exceed the capacity of the liquid receiver 4.

Next, the defrosting operation will be described.

(Defrosting operation of internal heat exchanger 5) If the cooling operation is performed for a long time, the moisture contained in the air in the storage C1 may freeze into frost and adhere to the fins of the internal heat exchanger 5. Since frost on the radiating fins hinders heat exchange, the defrosting operation of the internal heat exchanger 5 is performed to defrost. As shown in Fig. 11, this defrosting operation differs from the heating operation only in stopping the fan FM1 and the fan FM2.

(Defrosting operation of the external heat exchanger 3) If the temperature increase operation is performed for a long time, the moisture contained in the outside air may freeze and become frost, and it may adhere to the fins 3f of the external heat exchanger 3. As described above, in the refrigerating device 51, the accumulation of snow or frost on the fins 3f of the external heat exchanger 3 is extremely difficult to generate. However, when the refrigerated vehicle C is driven during snowfall, if the amount of snowfall is significantly greater, the space between the adjacent fins 3f on the windward side of the external heat exchanger 3 (the side of the first external heat exchanger 3A) It may also be blocked. At this time, since the heat exchange is hindered, the defrosting operation of the external heat exchanger 3 is performed, and snow melting and defrosting are performed on the fins 3f. As shown in Figure 11, this defrosting operation differs from the cooling operation only in stopping the fan FM1 and the fan FM2.

The specific parameters of the external heat exchanger 3 are, for example, set as follows: The thickness Ea of the first external heat exchanger 3A in the front-rear direction (refer to Fig. 5): 19.05 mm The thickness of the second external heat exchanger 3B in the front-rear direction Eb (refer to Figure 5): 57.15 mm Total thickness in the front and rear direction (Ea+Eb): 76.20 mm Height in the vertical direction Ec (refer to Figure 5): 355.6 mm Effective width in the left and right direction (width of the ventilation part) Ed ( Refer to Figure 5): 1050 mm Diameter of refrigerant piping (outer diameter): φ9.53 mm Pitch Ee of refrigerant piping (refer to Figure 4): 25.4 mm

[During cooling operation (external heat exchanger 3 functions as a condenser)] Heat dissipation capacity: 4.8 kW Refrigerant flow rate in the refrigerant pipe: Approximately 1.14 kg/min Flow velocity of the refrigerant in the pipe of the first external heat exchanger 3A : 0.165 m/s (m/s) (liquid state) The flow velocity of the refrigerant in the pipes of the second external heat exchanger 3B: 1.05 m/s (gas state), 0.11 m/s (liquid state)

[During heating operation (external heat exchanger 3 functions at least as an evaporator)] Heat absorption: 2.5 kW Refrigerant flow rate in the refrigerant pipe: Approximately 2.10 kg/min of the refrigerant in the pipe of the first external heat exchanger 3A Flow velocity: 0.260 m/s (liquid phase state) Flow velocity of the refrigerant in the piping of the second external heat exchanger 3B: 6.45 m/s (gas phase state), 0.173 m/s (liquid phase state) No. 1 external heat The temperature of the refrigerant at the inlet of the exchanger 3A: 20°C The temperature of the refrigerant at the outlet of the first external heat exchanger 3A: 5°C

The parameters of the external heat exchanger 3 are set to other specifications to obtain heat dissipation especially during cooling operation (4.8 kW in the above example). As an example of the setting procedure, firstly, since the second external heat exchanger 3B functions as a condenser during the cooling operation and functions as an evaporator during the temperature-rising operation, consider the parameters and the temperature-rising operation during the cooling operation. The parameters at the time are set to 3 rows (4 rows as a condenser), 14 steps, 3 paths (step "A"). Next, for example, the better path number condition, that is, Na<Nb, is used to set the path of the first external heat exchanger 3A to 2. Furthermore, the number of columns M is calculated to be 1, which is the maximum value in the range in which the capacity of the first external heat exchanger 3A does not exceed the capacity of the liquid receiver 4. In this step, the specification is set to, for example, 1 row, 14 segments and 2 paths (step "B").

As described above, when snow accumulates on the fins 3f of the first external heat exchanger 3A, the external heat exchanger 3 can melt the snow by the heating operation. The first external heat exchanger 3A only needs to release the heat that melts the snow, and the excess heat is only used to raise the temperature of the melted water, which is in vain. In addition, since the snow accumulates over the entire suction surface of the first external heat exchanger 3A, it is preferable to disperse the melting area over the entire suction surface as much as possible instead of locally melting. As shown in the parameter example, the difference between the inlet and outlet refrigerant temperatures in the first external heat exchanger 3A is, for example, 15°C (deg). For example, if the number of paths Na is 1, the inlet is on the upper side, and the outlet is on the lower side, only the upper side becomes the highest temperature and the lower side becomes the lowest temperature, and a gentle temperature gradient is generated in the vertical direction. Therefore, when the melting area and the non-melting area are generated, it is divided into two parts in the up and down direction.

In this regard, the number of paths Na is, for example, 2 as in the embodiment, and the area substantially occupied by each path is divided into an upper side and a lower side on the suction surface. Furthermore, an entrance of one path may be provided on the upper side, an exit of another path may be provided on the lower side, and the exit of the upper path and the entrance of the lower path may be arranged at the center of the vertical direction. At this time, since the temperature gradient in the vertical direction of the suction surface is "high-low-high-low" from the upper side to the lower side, when there is a melting area and a non-melting area, two melting and non-melting occur alternately. That is, "melting-non-melting-melting-non-melting". Therefore, the melting area is dispersed and better. Since the larger the number of paths Na, the more finely this dispersion spreads, which is better. In addition, the greater the number of paths Na, the less concentrated and dispersed the high temperature range. Therefore, it is possible to suppress the release of excess heat that raises the temperature of the melted water, which is preferable. In this way, the number of paths Na is preferably 2 or more.

The external heat exchanger 3 and the refrigerating device 51 of the embodiment are not limited to the above-mentioned configuration, and they may be modified as long as they do not deviate from the gist of the present invention.

(Modification 1) Modification 1 is that in the refrigerant circuit of the refrigeration unit 51, a gas-liquid heat exchanger for heat exchange is provided between the upstream piping line L6 and the downstream piping line L8 of the indoor heat exchanger 5 17 (refrigeration unit 51A) (refer to Fig. 12) example. Fig. 12 is a partial circuit diagram mainly showing a part of the refrigerant circuit of the refrigerating device 51A that is different from the refrigerant circuit of the refrigerating device 51 (see Fig. 1). The gas-liquid heat exchanger 17 is connected between the solenoid valve 11 and the expansion valve 12 with respect to the piping line L6. In addition, it is connected between the internal heat exchanger 5 and the branch portion D3 with respect to the piping line L8.

In the cooling operation of the refrigerating device 51A, the refrigerant circulates in the direction of the arrow in the piping portion indicated by the thick line shown in FIG. 12. The liquid refrigerant that is about to enter the expansion valve 12 during the cooling operation is cooled by heat exchange with the gaseous refrigerant flowing out of the internal heat exchanger 5 in the gas-liquid heat exchanger 17, and the degree of supercooling increases. In this way, since the heat exchange in the internal heat exchanger 5 is used, the amount of heat taken from the air in the compartment C1 is increased, and therefore, the cooling capacity in the compartment C1 is improved. In addition, since the evaporation of the liquid refrigerant in the internal heat exchanger 5 can be further promoted, the occurrence of the liquid hammer phenomenon of the compressor 1 can be prevented.

On the other hand, during the heating operation, the liquid refrigerant does not circulate through the piping line L6 but circulates through the piping line L7, so the gas-liquid heat exchanger 17 does not work.

(Modification 2) With respect to the freezing device 51, the modification 2 includes two or more indoor heat exchangers (the freezing device 51B). Here, with reference to Fig. 13, an example in which two internal heat exchangers 25A and 25B are provided will be described. FIG. 13 is a partial circuit diagram mainly showing a different part of the refrigerant circuit of the refrigerating device 51B from the refrigerant circuit of the refrigerating device 51 (see FIG. 1).

As shown in FIG. 13, the refrigeration unit 51B is connected in parallel between the receiver 4 and the branch portion D3, and the indoor heat exchanger 25A including the fan FM25A and the indoor heat exchanger 25B including the fan FM25B are connected in parallel. The expansion valve 22A is connected to the upstream side (the receiver 4 side) of the internal heat exchanger 25A, and the expansion valve 22B is connected to the upstream side of the internal heat exchanger 25B. The upstream sides of the expansion valves 22A and 22B merge into a single line, and are connected to the receiver 4 via the solenoid valve 23. A solenoid valve 21A is provided between the internal heat exchanger 25A and the expansion valve 22A and between the liquid receiver 4. A solenoid valve 21B is provided between the internal heat exchanger 25B and the expansion valve 22B and between the liquid receiver 4. The downstream sides of the expansion valves 22A and 22B merge into one line, which is connected to the branch D3. The operations of the fan FM25A and the fan FM25B, and the solenoid valve 21A and the solenoid valve 21B are controlled by the control unit 31.

This refrigerating device 51B is mounted, for example, in a refrigerating vehicle equipped with two or more compartments that should maintain a constant temperature. The internal heat exchanger 25A and the internal heat exchanger 25B are installed so as to cool and raise the temperature of the inside of the respective different compartments.

The number and position of solenoid valves are not limited to the example shown in Fig. 13.

According to this modification 2, the open state and the closed state of the solenoid valves 21A, 21B, and 23 can be combined to independently cool or raise the temperature of two or more compartments. For example, it is possible to cool only a specific one or two or more specific compartments, or to cool all the compartments.

Modification 1 and Modification 2 can be appropriately combined.

The flow direction restricting portion RK is not limited to the use of two or more check valves. However, depending on the use of check valves, the flow direction restricting portion RK can be constructed at a relatively low cost.

(Modification 3) In Modification 3, the refrigerating device 51 is made into a refrigerating device 57 having a refrigerant circuit that does not include the flow direction restricting portion RK and can perform a cooling operation and a temperature-rising operation. The configuration of the refrigerating device 57 is shown in Fig. 14 which is the refrigerant circuit diagram and Fig. 15 which shows the control system. That is, with respect to the refrigerant circuit of the refrigeration device 51, the refrigerant circuit of the refrigeration device 57 deletes the flow direction restricting portion RK, and makes the parallel circuit LP2 replace the solenoid valve 11 and the solenoid valve 13 with the check valve 71 and the check valve, respectively 73 made up of parallel loop LP72. The other configurations are the same.

Since this configuration does not include the flow direction restricting portion RK, the direction of the refrigerant flowing in the indoor heat exchanger 5 is reversed during the cooling operation and the temperature increase operation. That is, in the parallel circuit LP72, when the refrigerant flows from the receiver 4 into the internal heat exchanger 5, it circulates through the piping line L76; and when the refrigerant circulates from the internal heat exchanger 5 to the receiver 4, it circulates through the piping Line L77.

The cooling operation and the heating operation of the refrigeration device 57 will be mainly described with reference to FIGS. 16 to 18. Fig. 16 is a diagram for explaining the refrigerant circuit during the cooling operation. Fig. 17 is a diagram for explaining the refrigerant circuit during the heating operation. Fig. 18 is a table for explaining the control of the control unit 31 during each operation. In Figs. 17 and 18, similar to Figs. 9 and 10, the piping portion where the refrigerant flows is indicated by thick lines, and the flow direction of the refrigerant is indicated by arrows along the piping.

(Cooling operation) As shown in the table of FIG. 18, in the cooling operation of the refrigeration device 57, the control unit 31 sets the four-way valve 2 to mode A, and the fan FM1 and the fan FM2 are in the operating state. The blowing directions generated by the fan FM1 and the fan FM2 during this cooling operation are indicated by the arrow DR71 and the arrow DR72 in Fig. 16, respectively. The phase state of the refrigerant from the port 3Ba to the port 3Aa of the external heat exchanger 3 and the function of the external heat exchanger 3 are the same as the cooling operation of the refrigerating device 51. That is, in the cooling operation of the refrigerating device 57, the second external heat exchanger 3B of the external heat exchanger 3 and the first external heat exchanger 3A function as a condenser integrally. In this way, the gaseous refrigerant dissipates heat to the outside air and condenses, and flows into the piping line L5 from the port 3Aa in the form of a high-pressure liquid refrigerant.

Almost all of the refrigerant flowing into the piping line L5 becomes a liquid phase under high pressure. This liquid refrigerant flows through the receiver 4 and flows into the parallel circuit LP72. In the parallel circuit LP72, only the liquid refrigerant is allowed to flow into the piping line L76 via the check valve 71 and enter the expansion valve 72. In the expansion valve 72, the liquid refrigerant expands. In this way, the liquid refrigerant is reduced in pressure and temperature, and gasification is promoted, and it becomes a gas-liquid mixed refrigerant in which the gas phase and the liquid phase are mixed. The gas-liquid mixed refrigerant flowing out of the expansion valve 72 flows into the internal heat exchanger 5.

In the internal heat exchanger 5, the fan FM2 is in an operating state under the control of the control unit 31, and causes the air in the compartment C1 to flow in the direction of the arrow DR72 in Fig. 16. In this state, the gas-liquid mixed refrigerant exchanges heat with the air in the storage C1, obtains heat from the air in the storage C1, and is completely vaporized to become a gaseous refrigerant. That is, the internal heat exchanger 5 functions as an evaporator, and the inside of the storage C1 is cooled.

The gaseous refrigerant flowing out of the internal heat exchanger 5 flows into the piping line L8. In the refrigerating device 57, the piping line L8 connects the internal heat exchanger 5 and the port 2d of the four-way valve 2 without branching. Therefore, the gaseous refrigerant flows from the port 2d of the four-way valve 2 of the mode A through the port 2c, and further flows through the accumulator 6 and returns to the suction port of the compressor 1.

(Temperature Warming Operation) As shown in the table of FIG. 18, during the temperature raising operation of the refrigerator 57, the control unit 31 sets the four-way valve 2 to mode B, and the fan FM1 and the fan FM2 are in the operating state. The blowing direction generated by the fan FM1 and the fan FM2 during the heating operation is the same as the cooling operation, and is a constant direction, and is indicated by an arrow DR73 and an arrow DR74 in FIG. 17, respectively.

As shown in FIG. 17, under the control of the control unit 31, the high-pressure gaseous refrigerant discharged from the discharge port of the compressor 1 flows from the port 2a of the four-way valve 2 in the mode B through the port 2d, and flows into the piping line L8. In the refrigerating device 57, as described above, the piping line L8 connects the port 2d of the four-way valve 2 and the internal heat exchanger 5 without any branch. Therefore, the direction in which the gaseous refrigerant flows into the internal heat exchanger 5 is opposite to the direction in which it flows into the internal heat exchanger 5 during the cooling operation.

In the internal heat exchanger 5, as described above, according to the control of the control unit 31, the fan FM2 is in the operating state, and the air in the compartment C1 flows in the direction of the arrow DR74 in FIG. 17. In this state, the gaseous refrigerant exchanges heat with the air in the storage C1, releases heat to the air in the storage C1, condenses, and substantially becomes a high-pressure liquid refrigerant. Therefore, the temperature in the bank C1 is increased.

The liquid refrigerant flowing out of the internal heat exchanger 5 flows through the piping line L77 with the check valve 73 of the parallel circuit LP72 and the receiver 4, and flows from the port 3Aa into the first reservoir of the external heat exchanger 3 through the piping line L5. External heat exchanger 3A.

In the external heat exchanger 3, under the control of the control unit 31, the fan FM1 is in the operating state, and the outside air flows in the direction of the arrow DR73 in FIG. 17. Therefore, the first external heat exchanger 3A is located on the upstream side of the flow of outside air with respect to the second external heat exchanger 3B. In this state, the liquid refrigerant is cooled in the first external heat exchanger 3A, and the temperature drops. That is, the first external heat exchanger 3A functions as a supercooling heat exchanger for the liquid refrigerant. The gaseous refrigerant flowing into the first external heat exchanger 3A together with the liquid refrigerant is also cooled by this and almost all becomes the liquid refrigerant.

The supercooled liquid refrigerant flows out of the port 3Ab of the first external heat exchanger 3A, and flows into the piping line L3. In the piping line L3, the liquid refrigerant enters the expansion valve 7 via the check valve 8. In the expansion valve 7, the liquid refrigerant expands. In this way, the liquid refrigerant is reduced in pressure and temperature, and gasification is promoted, and it becomes a gas-liquid mixed refrigerant in which the gas phase and the liquid phase are mixed. The gas-liquid mixed refrigerant flowing out of the expansion valve 7 flows into the second external heat exchanger 3B from the port 3Bb. In the second external heat exchanger 3B, the gas-liquid mixed refrigerant flowing in from the port 3Bb obtains heat from the outside air by heat exchange with the outside air, evaporates, becomes a gaseous refrigerant, and flows into the piping line L2 from the port 3Ba. That is, the second external heat exchanger 3B functions as an evaporator. The gaseous refrigerant flowing into the piping line L2 passes through the port 2b of the four-way valve 2 in the mode B, passes through the port 2c, flows through the accumulator 6 and returns to the suction port of the compressor 1.

Next, the defrosting operation of the refrigerating device 57 will be described.

(Defrosting operation of the internal heat exchanger 5) Even in the refrigeration unit 57, if the cooling operation is performed for a long time, the moisture contained in the air in the storage C1 may freeze into frost and adhere to the internal heat exchanger 5 on the heat sink. Since frost on the radiating fins hinders heat exchange, the defrosting operation of the internal heat exchanger 5 is performed to defrost. As shown in the table in Fig. 18, this defrosting operation differs from the heating operation only in stopping the fan FM1 and the fan FM2.

(Defrosting operation of the external heat exchanger 3) Even in the refrigeration unit 57, if the temperature increase operation is performed for a long time, the moisture contained in the outside air may freeze and become frost and adhere to the external heat exchanger 3 On the heat sink 3f. In the freezing device 57, the function of the external heat exchanger 3 is the same as that of the freezing device 51. Therefore, the accumulation of snow or frost on the fins 3f of the external heat exchanger 3 is extremely unlikely to occur. However, when the refrigerated vehicle C is driven during snowfall, if the amount of snowfall is significantly greater, the adjacent fins 3f on the windward side of the external heat exchanger 3 (the first external heat exchanger 3A side) will also be spaced between the adjacent fins 3f. It may be clogged. At this time, since the heat exchange is hindered and cannot function as a heat exchanger, the defrosting operation of the external heat exchanger 3 is performed to melt snow and defrost the fins 3f. As shown in the table in Figure 18, this defrosting operation differs from the cooling operation only in stopping the fan FM1 and the fan FM2.

In particular, the refrigerating device 57 obtains the following effects during the heating operation.

In the second external heat exchanger 3B, the gas-liquid mixed refrigerant performs heat exchange to obtain heat from the outside air, and becomes a low-pressure gas refrigerant. In the external heat exchanger 3, a plurality of fins 3f are provided so as to straddle the first external heat exchanger 3A and the second external heat exchanger 3B. Therefore, in the first external heat exchanger 3A, part of the heat released by the liquid refrigerant is transferred to the fins 3f and moved to the second external heat exchanger 3B as the phase in the second external heat exchanger 3B. The changed heat of evaporation is utilized. In this way, since the evaporation of the liquid refrigerant in the second external heat exchanger 3B is promoted, it is possible to prevent the liquid refrigerant from being sucked into the compressor 1, which is the so-called liquid hammer phenomenon.

In addition, even if the operating environment is, for example, driving in a cold area, when snow accumulates on the fins 3f due to snowfall, the snow adhering to the fins 3f will be affected by the first external heat exchanger due to the fins 3f. The heat released by the heat exchange during the heating operation becomes warm and melts. In addition, the portion of each of the plurality of fins 3f on the side of the second external heat exchanger 3B becomes warm due to the following reason: the outside air heated by the heat exchange in the first external heat exchanger 3A , Circulates to the downstream side; and, the heat imparted to the fin 3f by heat exchange in the first external heat exchanger 3A is transferred to the downstream side of the fin 3f. In this way, since all the heat sinks 3f are warmed efficiently, it is extremely effective to prevent snow or frost on the heat sinks 3f. Therefore, the execution interval of the defrosting operation of the refrigerating device 57 becomes longer, and the operation efficiency is improved.

In addition, the first external heat exchanger 3A has two or more paths P1 and P2, and each path is arranged in such a way that it does not substantially overlap in the air blowing direction (front-to-rear direction) and becomes substantially independent on the suction surface area. In this way, since the unevenness of the surface temperature of the suction surface is suppressed, the snow adhering to the heat sink 3f is uniformly melted.

(Modification 4) The parallel circuit LP1 connecting the port 3Ab of the first external heat exchanger 3A and the port 3Bb of the second external heat exchanger 3B (refer to Figures 1, 4, 9 and 10 ), as Modification 4, it can also be replaced with a parallel circuit LP1a without the check valve 8.　 Figure 19 shows this parallel circuit LP1a.

(Other modification examples) At least one of the external heat exchanger 3 and the internal heat exchanger 5 is not limited to the above-mentioned fin-and-tube heat exchanger. It can also be serpentine or parallel flow, and the same effect will be obtained in this case. The case where the external heat exchanger 3 is not a fin-tube heat exchanger will be described in detail. First, prepare two serpentine or parallel-flow heat exchangers, which are arranged side by side in the front-rear direction. Furthermore, the refrigerant pipes are respectively connected so that one of the heat exchangers functions as the first external heat exchanger 3A, and the other heat exchanger functions as the second external heat exchanger 3B. Furthermore, a plurality of heat exchange fins are respectively installed across the refrigerant pipes of the two heat exchangers to integrate the two heat exchangers.

The above-mentioned embodiments and various modified examples can also be implemented in combination as much as possible. For example, it is possible to combine Modification 1 and Modification 3, and apply the gas-liquid heat exchanger 17 to the refrigeration device 57. At this time, in the portion shown in FIG. 12 of the refrigerant circuit, the solenoid valve 11 is replaced with the check valve 71, and the solenoid valve 13 is replaced with the check valve 73.

1‧‧‧Compressor 2‧‧‧Four-way valve 2a～2d‧‧‧Port 3‧‧‧External heat exchanger 3A‧‧‧The first external heat exchanger 3Aa, 3Ab‧‧‧Port 3B‧‧ ‧The second external heat exchanger 3Ba, 3Bb‧‧‧Port 3C‧‧‧Tube 3f‧‧‧Radiating fins 3LA, 3LB‧‧‧Refrigerant piping line 4‧‧‧Acceptor 5, 25A, 25B‧‧‧ Internal heat exchanger 6‧‧‧Accumulator 7,12,22A,22B,72‧‧‧Expansion valve 8～10,14～16,71,73‧‧‧Check valve 11,13,21A,21B, 23‧‧‧Solenoid valve 17‧‧‧Gas-liquid heat exchanger 31‧‧‧Control unit 32‧‧‧Input unit 51, 51A, 51B, 57‧‧‧Refrigeration device C‧‧‧Refrigerator car C1‧‧‧Storage (Container) CV‧‧‧Internal space D1～D4‧‧‧Branch G, GA1, GA2, GB3～GB5‧‧‧Piping train group FM1, FM2, FM25A, FM25B‧‧‧Fan (blower) LP1, LP2 LP72, LP1A‧‧‧Parallel circuit L1～L11, 3LA, 3LB, L76, L77‧‧‧Pipe line Na, Nb‧‧‧Number of paths P1～P5‧‧‧Path Qa, Qb‧‧‧Capacity RA, RB‧ ‧‧Flow Path RK‧‧‧Circulation Direction Restriction Section S‧‧‧Container

Fig. 1 is an example of a heat exchanger for a refrigeration system and a refrigeration system according to the present invention, that is, a refrigerant circuit diagram of an external heat exchanger 3 and a refrigeration system 51 using the external heat exchanger 3. FIG. 2 is a diagram for explaining the control system of the refrigeration device 51. As shown in FIG. FIG. 3 is a diagram for explaining the control modes of the four-way valve 2, the solenoid valve 11, and the solenoid valve 13 in the refrigeration system 51. As shown in FIG. FIG. 4 is a schematic cross-sectional view for explaining the external heat exchanger 3 in the refrigeration unit 51. As shown in FIG. FIG. 5 is a first perspective view for explaining the external heat exchanger 3. FIG. 6 is a second perspective view for explaining the external heat exchanger 3. FIG. 7 is a diagram for explaining the path in the external heat exchanger 3. Fig. 8 is a side view of the refrigerating vehicle C, which is an example of the placement of the refrigerating device 51. FIG. 9 is a refrigerant circuit diagram for explaining the cooling operation of the refrigerating device 51. As shown in FIG. Fig. 10 is a refrigerant circuit diagram for explaining the temperature-raising operation of the refrigerating device 51. FIG. 11 is a table for explaining the control performed by the control unit 31 in the refrigeration system 51. As shown in FIG. Fig. 12 is a partial refrigerant circuit diagram for explaining the main part of the refrigerant circuit in the refrigeration system 51A in Modification 1. Fig. 13 is a local refrigerant circuit diagram for explaining the main part of the refrigerant circuit in the refrigeration system 51B in Modification 2. Fig. 14 is a circuit diagram of the refrigerant circuit in the refrigerating system 57, which is the third modification. Fig. 15 is a diagram for explaining the control system of the refrigerating device 57. Fig. 16 is a refrigerant circuit diagram for explaining the cooling operation of the refrigeration unit 57. Fig. 17 is a refrigerant circuit diagram for explaining the temperature-raising operation of the refrigeration unit 57. FIG. 18 is a table for explaining the control performed by the control unit 31 in the refrigeration system 57. Fig. 19 is a diagram for explaining the parallel circuit LP1a of Modification 4.

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3‧‧‧External heat exchanger

3A‧‧‧The first external heat exchanger

3Aa、3Ab‧‧‧Port

3B‧‧‧The second external heat exchanger

3Ba, 3Bb‧‧‧Port

3C‧‧‧Tube

3LA, 3LB‧‧‧Refrigerant Piping Line

7‧‧‧Expansion valve

8,9‧‧‧Check valve

GA1, GA2, GB3~GB5‧‧‧Piping array group

FM1‧‧‧Fan (blower)

LP1‧‧‧Parallel circuit

L2, L3, L4, L9‧‧‧Piping line

P1~P5‧‧‧Path

Claims (2)

A heat exchanger for a refrigeration device, which is a fin-tube type heat exchanger for a refrigeration device, used as an external heat exchanger of the refrigeration device, wherein the refrigeration device is provided with a refrigerant circuit, and the refrigerant circuit includes an internal heat exchanger and The aforementioned external heat exchanger, and the refrigeration device can selectively perform a cooling operation to cool the interior and a temperature increase operation to raise the temperature in the interior, and the heat exchanger for a refrigeration device includes: a first heat exchanger having a first heat exchanger 1 refrigerant piping line; second heat exchanger, which has a second refrigerant piping line connected in series to the first refrigerant piping line, and is arranged in parallel with the first heat exchanger; a plurality of radiating fins, which are arranged across and connected On both sides of the first refrigerant piping line and the second refrigerant piping line; and, a blower that blows air to the first heat exchanger and the second heat exchanger; and, in the blowing direction of the blower, The first refrigerant piping line has one row, and the piping of the second refrigerant piping line has multiple rows; the piping of the first refrigerant piping line and the piping of the second refrigerant piping line pass through the first heat exchanger orthogonally It is connected to the respective fins of the second heat exchanger; the first refrigerant piping line has a plurality of paths, the number of paths is Na, and Na is an integer of 2 or more, and the second refrigerant piping line has a plurality of paths, The number of paths is Nb, and Nb is an integer greater than or equal to 3, the aforementioned number of paths Na and the aforementioned number of paths Nb satisfy 2

Na<Nb; the plural paths of the first refrigerant piping line are connected in parallel between one end and the other end, and are arranged as substantially independent areas on the suction surface of the first heat exchanger; The multiple paths of the refrigerant piping line are connected in parallel in a completely fluid-independent manner between one end and the other end, and do not overlap each other in the blowing direction generated by the blower, and are sucked in by the second heat exchanger The surface is arranged as a substantially independent area; each path of the second refrigerant piping line is arranged to pass through all the rows of the plurality of rows of the second heat exchanger; in the air flow generated by the air blower, The first heat exchanger is placed on the upstream side and the second heat exchanger is placed on the downstream side. In the cooling operation, the gaseous refrigerant is condensed in the second heat exchanger, and then the gas refrigerant is condensed in the second heat exchanger. In the first heat exchanger, the gaseous refrigerant that is not condensed in the second heat exchanger is condensed, and the speed of the condensed refrigerant flowing through the piping of the first refrigerant piping line is greater than that of the second refrigerant piping The speed of the condensed refrigerant in the piping of the circuit increases the degree of subcooling of the refrigerant; in the heating operation, the degree of subcooling of the liquid refrigerant is increased in the first heat exchanger, and it functions as an evaporator In the second heat exchanger, the liquid refrigerant is evaporated, and heat is transferred from the first heat exchanger to the second heat exchanger via the plurality of fins. The heat exchanger for a refrigeration system according to claim 1, wherein an expansion valve is provided between the first refrigerant piping line and the second refrigerant piping line, and the expansion valve is only used to allow the refrigerant to flow from the first refrigerant piping line. It functions during the temperature increase operation that flows to the second refrigerant piping line.

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