JP6603768B2 - Heat exchanger for refrigeration equipment - Google Patents

Description

  The present invention relates to a heat exchanger for a refrigeration apparatus, and more particularly to a heat exchanger for a refrigeration apparatus used for a refrigeration apparatus that can selectively execute a cooling operation and a heating operation.

As a refrigerated vehicle used to deliver goods to convenience stores, etc., it can not only cool the interior but also heat it to keep the cargo loaded in the warehouse at the optimum temperature regardless of the outside temperature. A refrigeration vehicle equipped with a device has been put into practical use.
With this refrigeration system, the inside of the refrigerator is cooled mainly in the summer when the outside air temperature is higher than the maintenance temperature, and is warmed mainly in the winter when the outside air temperature is lower than the maintenance temperature.
An example of this refrigeration apparatus is described in Patent Document 1 as a refrigeration apparatus for land transportation. The refrigeration apparatus for land transportation described in Patent Document 1 is a heat pump type.

In general, when the freezer truck is running during snowfall, the external heat exchanger may not function as a heat exchanger for heating operation due to adhesion of snow that blows in. In that case, a defrost operation is performed to melt the attached snow.
However, if the defrost operation is frequently executed, that is, if the execution interval of the defrost operation is shortened, the efficiency of the heating operation is lowered.
Therefore, the refrigeration apparatus for land transportation described in Patent Document 1 has a structure that prevents the execution interval of the defrost operation from being shortened in the heating mode operation in the traveling of the refrigeration vehicle during snowfall.
Specifically, the duct for guiding the exhaust air of the engine of the refrigeration vehicle to the suction side of the external heat exchanger, the opening / closing means for the air passage in the duct, and the suction side so as to cover the external heat exchanger And a panel disposed in front.

  For example, the panel 27 prevents snow from directly blowing into the external heat exchanger. Thereby, snow accretion is suppressed and the function as a heat exchanger is maintained, so that it is not necessary to shorten the defrosting operation interval.

JP 2010-255909 A

However, in the refrigeration apparatus described in Patent Document 1, since the panel is arranged in front of the suction side so as to cover the external heat exchanger, the traveling wind during traveling of the refrigerator car is blocked by the panel. It does not hit the external heat exchanger directly.
Therefore, in the cooling operation in which the external heat exchanger acts as a condenser, there may be a case where a sufficient air volume is not ensured.
If a sufficient air volume is not ensured, there is a problem that the refrigerant is not sufficiently condensed and the cooling capacity is lowered.
Therefore, it is desired that the required defrosting operation interval can be extended without reducing the cooling capacity for the heat exchanger and the refrigeration apparatus for the refrigeration apparatus.

  Therefore, the problem to be solved by the present invention is to provide a heat exchanger for a refrigeration apparatus that can lengthen the execution interval of a necessary defrost operation without reducing the cooling capacity.

In order to solve the above problems, the present invention has the following configuration.
1) The external heat exchange of the refrigeration apparatus which includes a refrigerant circuit including an internal heat exchanger and an external heat exchanger and can selectively perform a cooling operation for cooling the internal space and a heating operation for heating. A fin-and-tube type heat exchanger for refrigeration equipment used as a storage device,
A first heat exchanger having a first refrigerant piping path;
A second heat exchanger having a second refrigerant piping path connected in series to the first refrigerant piping path and arranged in parallel to the first heat exchanger;
A plurality of fins provided across both the piping of the first refrigerant piping path and the piping of the second refrigerant piping path;
A blower for blowing air to the first heat exchanger and the second heat exchanger;
With
The piping of the first refrigerant piping path and the piping of the second refrigerant piping path are connected so as to orthogonally pass through the plurality of fins,
The first refrigerant piping path has a plurality of paths with a number of passes Na (Na: integer of 2 or more), and the second refrigerant piping path has a plurality of paths with a number of paths Nb (Nb: integer of 3 or more). The number of passes Na and the number of passes Nb satisfy 2 ≦ Na <Nb,
In the ventilation by the blower, the first heat exchanger is arranged on the upstream side, and the second heat exchanger is arranged on the downstream side,
Each of the plurality of paths of the first refrigerant piping path is disposed as a substantially independent region on the air suction surface of the first heat exchanger,
Each of the plurality of paths of the second refrigerant piping path is disposed as a substantially independent region on the suction surface of the air blowing in the second heat exchanger,
In the cooling operation, after the gaseous refrigerant is condensed in the second heat exchanger, the non-condensed gaseous refrigerant is condensed in the second heat exchanger in the first heat exchanger. And the speed of the condensed refrigerant flowing through the pipe of the first refrigerant piping path is made larger than the speed of the condensed refrigerant flowing through the pipe of the second refrigerant piping path, It functions to increase the degree of supercooling of the condensed refrigerant flowing through the pipe ,
Wherein in the heating operation, the refrigerant liquid, said with Ru said evaporated in the second heat exchanger is made to function as an evaporator after increasing the degree of supercooling in the first heat exchanger, the first The heat released from the liquid refrigerant in the heat exchanger is transmitted to the second heat exchanger via the plurality of fins to promote the evaporation of the liquid refrigerant in the second heat exchanger. Is a heat exchanger for a refrigeration apparatus.
2) The refrigeration apparatus according to 1), wherein in the blowing direction of the blower, the first refrigerant piping path has one row and the second refrigerant piping path has a plurality of rows. Heat exchanger.
3) Functions only in the heating operation in which the refrigerant flows from the first refrigerant piping path to the second refrigerant piping path between the first refrigerant piping path and the second refrigerant piping path. The heat exchanger for a refrigeration apparatus according to 1) or 2), further comprising an expansion valve.

  According to the present invention, it is possible to increase the execution interval of the necessary defrost operation without reducing the cooling capacity.

It is a refrigerant circuit diagram of the external heat exchanger 3 which is an Example of the heat exchanger for freezing apparatuses of this invention, and the freezing apparatus 51 using the same. It is a figure for demonstrating the control system of the freezing apparatus 51. FIG. FIG. 6 is a diagram for explaining control modes of the four-way valve 2, the electromagnetic valve 11, and the electromagnetic valve 13 in the refrigeration apparatus 51. It is a typical sectional view for explaining outside heat exchanger 3 in refrigeration equipment 51. It is a 1st perspective view for demonstrating the heat exchanger 3 outside a store | warehouse | chamber. It is a 2nd perspective view for demonstrating the heat exchanger 3 outside a store | warehouse | chamber. It is a figure for demonstrating the path | pass in the heat exchanger 3 outside a store | warehouse | chamber. It is a side view for demonstrating the refrigerator car C which is the example of mounting of the freezing apparatus 51. FIG. 4 is a refrigerant circuit diagram for explaining a cooling operation of the refrigeration apparatus 51. FIG. 4 is a refrigerant circuit diagram for explaining a heating operation of the refrigeration apparatus 51. FIG. It is a table | surface for demonstrating the control which the control part 31 in the freezing apparatus 51 performs. It is a partial refrigerant circuit diagram for demonstrating the principal part of the refrigerant circuit in 51 A of refrigeration apparatuses which are the modifications 1. FIG. It is a partial refrigerant circuit diagram for demonstrating the principal part of the refrigerant circuit in the freezing apparatus 51B which is the modification 2. As shown in FIG. FIG. 12 is a refrigerant circuit diagram in a refrigeration apparatus 57 that is Modification 3. It is a figure for demonstrating the control system of the freezing apparatus 57. FIG. 4 is a refrigerant circuit diagram for explaining a cooling operation of the refrigeration apparatus 57. FIG. 6 is a refrigerant circuit diagram for explaining a heating operation of the refrigeration apparatus 57. FIG. It is a table | surface for demonstrating the control which the control part 31 in the freezing apparatus 57 performs. It is a figure for demonstrating the parallel circuit LP1a of the modification 4.

  A heat exchanger for a refrigeration apparatus according to an embodiment of the present invention includes an external heat exchanger 3 of an example, a refrigeration apparatus 51 using the heat exchanger 3 and modifications thereof, and FIGS. The description will be given with reference.

<Example>

The configuration of the refrigeration apparatus 51 is shown in FIG. 1 which is the refrigerant circuit diagram and FIG. 2 which shows the control system.
That is, the refrigerant circuit of the refrigeration apparatus 51 includes a compressor 1, a four-way valve 2, a fan FM1 that is a fan driven by a motor, an external heat exchanger 3, a liquid receiver 4, and a fan FM2 that is a fan driven by a motor. The internal heat exchanger 5, the accumulator 6, the electromagnetic valve 11, and the electromagnetic valve 13 are configured.

The operation of the compressor 1, the four-way valve 2, the fan FM1, the fan FM2, the electromagnetic valve 11, and the electromagnetic valve 13 in the refrigerant circuit is controlled by the control unit 31.
An instruction regarding driving from the user is transmitted to the control unit 31 via the input unit 32.

The external heat exchanger 3 and the internal heat exchanger 5 are of a so-called fin and tube type. The external heat exchanger 3 includes a first external heat exchanger 3A, a second external heat exchanger 3B, a first external heat exchanger 3A, and a second external heat exchanger 3B as a refrigerant circuit. And a circuit connected in series (parallel circuit LP1).
The first external heat exchanger 3A has a refrigerant piping path 3LA (see FIGS. 4 and 7) that connects the port 3Aa and the port 3Ab. In addition, the second external heat exchanger 3B includes a refrigerant piping path 3LB (see FIGS. 4 and 7) that connects the port 3Ba and the port 3Bb. Details of the external heat exchanger 3 will be described later.

The refrigerant circuit of the refrigeration apparatus 51 will be described in detail.
The compressor 1 and the port 2a of the four-way valve 2 are connected by a piping path 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 path 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 a parallel circuit LP1.

The parallel circuit LP1 has a piping path L3 and a piping path L4.
The piping path L3 is connected in series to the expansion valve 7 and the first external heat exchanger 3A side with respect to the expansion valve 7, and flows from the first external heat exchanger 3A toward the second external heat exchanger 3B. And a check valve 8 that permits only the above.
A check valve 9 that allows only the flow from the second external heat exchanger 3B to the first external heat exchanger 3A is disposed in the piping path L4.

The port 3Aa of the first external heat exchanger 3A and the liquid receiver 4 are connected by a piping path L5.
The piping path L5 is provided with a branch portion D1 and a branch portion D2 on the way. Between the branch part D1 and the branch part D2, a check valve 10 that allows only a flow from the first external heat exchanger 3A to the liquid receiver 4 is disposed.

The liquid receiver 4 and the internal heat exchanger 5 are connected via a parallel circuit LP2. The parallel circuit LP2 has a piping path L6 and a piping path L7.
In the piping path L6, an electromagnetic valve 11 and an expansion valve 12 connected in series to the internal heat exchanger 5 side with respect to the electromagnetic valve 11 are disposed.
An electromagnetic valve 13 is disposed in the piping path L7.

  The internal heat exchanger 5 and the port 2d of the four-way valve 2 are connected by a piping path L8. The piping path L8 is provided with a branch portion D3 and a branch portion D4 on the way. Between the branch part D3 and the branch part D4, a check valve 14 that allows only the flow from the internal heat exchanger 5 toward the four-way valve 2 is disposed.

The branch part D3 in the pipe route L8 and the branch part D1 in the pipe route L5 are connected by a pipe route L9. A check valve 15 that allows only a flow from the branching portion D3 to the branching portion D1 is disposed in the piping path L9.
The branch part D4 in the pipe route L8 and the branch part D2 in the pipe route L5 are connected by a pipe route L10. A check valve 16 that allows only a flow from the branching part D4 to the branching part D2 is disposed in the piping path L10.
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 a flow direction restricting portion RK.
The flow direction regulating unit RK regulates the flow direction of the refrigerant that enters and exits the port 3Aa of the external heat exchanger 3 according to the flow path selection accompanying the switching of the four-way valve 2. Details will be described later.

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

For this refrigerant circuit, the control unit 31 selectively controls the operation of the four-way valve 2 so as to be in either mode A or mode B.
Specifically, with reference to FIG. 3, mode A is a mode in which the port 2a and the port 2b are connected, and the port 2c and the port 2d are connected.
Mode B is a mode in which the port 2a and the port 2d are connected, and the port 2b and the port 2c are connected.
In mode A, the flow path RA is selected by the four-way valve 2 as the path through which the refrigerant flows (see the thick line path in FIG. 9). Further, in mode B, the flow path RB is selected (see the bold line path 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.
Moreover, the control part 31 controls the solenoid valve 11 and the solenoid valve 13 to open alternately. This control is executed in conjunction with the operation of the four-way valve 2.
Specifically, as shown in FIG. 3, in mode A, the electromagnetic valve 11 is opened and the electromagnetic valve 13 is closed. In mode B, the solenoid valve 11 is closed and the solenoid valve 13 is opened.

Next, the detail of the external heat exchanger 3 is demonstrated with reference to FIGS.
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 as viewed from the diagonally lower left, and FIG. 6 is an external perspective view of the external heat exchanger 3 as viewed from diagonally downward to the right. FIG. 7 is a view for explaining paths inside the external heat exchanger 3 (refrigerant piping paths 3LA, 3LB).
Each of the up, down, left, and right and front directions shown in FIGS. 4 to 6 is a direction set for convenience of understanding and does not limit the installation posture or the like.

The external heat exchanger 3 is configured as a fin-and-tube type as described above.
As shown in FIG. 4, the tube 3c as a tube has four rows in the front-rear direction and 14 rows in the vertical direction in the cross section. That is, if M rows and N stages of fin and tube are used, M = 4 and N = 14.
Each tube 3c is disposed so as to be folded at both the left and right ends so as to be connected as shown by the thick line in FIG.

Of the four rows, one row on the foremost 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 14 rows and 1 row, and the second external heat exchanger 3B has 14 rows and 3 rows.
Here, one row or a plurality of rows connected in series is referred to as a piping row group G. The case of one row is also referred to as a “pipe row group” for convenience.
Accordingly, the first external heat exchanger 3A has one line of piping rows GA with M = 1, and the second external heat exchanger 3B has three rows of pipe rows GB with M = 3. .
Further, in the first external heat exchanger 3A, the upper seven stages of the pipes 3cA constitute one refrigerant piping path to form a path P1, and the lower seven stages of the pipe 3cA constitute one refrigerant piping path. Path P2.
In the second external heat exchanger 3B, a total of 14 pipes 3cB in each of the upper five rows or the four rows are formed as one refrigerant piping path to form a path P3, and each row 5 in the center portion. A total of 14 pipes 3cB in 14 stages or 4 stages constitute one refrigerant piping path to form a path P4, and a total of 14 pipes 3cB in a total of 14 stages in 5 or 4 stages on the lower side The path P5 is configured as a refrigerant piping path.
Therefore, as shown in FIG. 4, in the first external heat exchanger 3A, a pipe line group GA1 and a pipe line group GA2 are provided corresponding to the path P1 and the path P2, respectively. Further, in the second external heat exchanger 3B, pipe line groups GB3 to GB5 are provided corresponding to the paths P3 to P5, respectively.

The number of passes Na of the first external heat exchanger 3A is an integer of 2 or more and the number of passes 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 apparatus 51 satisfies this relationship, and as described above, the number of passes Na of the first external heat exchanger 3A is 2, and the number of passes of the second external heat exchanger 3B. Nb 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 is branched and 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.
Further, as shown in FIG. 4, the path P <b> 1 and the path P <b> 2 are arranged so as to be substantially independent areas on the suction surface without overlapping each other in the blowing direction (front-rear direction).

In the second external heat exchanger 3B, the port 3Ba is branched into three and connected to one ends of the paths P3 to P5, respectively. The port 3Bb is branched into three and connected to the other ends of the paths P3 to P4.
That is, as shown in FIG. 7, paths P3 to P5 are connected in parallel between the port 3Ba and the port 3Bb.
As shown in FIG. 4, the paths P <b> 3 to P <b> 5 do not substantially overlap each other in the air blowing direction (front-rear direction) and are substantially independent regions on one side of the suction side (hereinafter also referred to as “suction surface”). Has been placed.

In the first external heat exchanger 3A, the smaller the number of passes Na, the larger the area occupied by one pass on the suction surface, and thus the surface temperature unevenness of the first external heat exchanger 3A is likely to be noticeable.
Therefore, if the number of passes Na is increased, the area occupied by one pass on the suction surface is reduced, and the surface temperature unevenness is suppressed as a whole.
That is, increasing the number of passes Na is preferable from the viewpoint of suppressing surface temperature unevenness.
On the other hand, when a plurality of passes are provided, the flow rate of the refrigerant passing through the passes decreases as the number of passes Na increases.
Therefore, in the design, the number of passes Na is set so that the heat exchange function can be satisfactorily performed in consideration of the degree of unevenness of the surface temperature and the flow rate of the refrigerant.
For example, the number of passes Na of the first external heat exchanger 3A may be set to the same number (Na = Nb) as the number of passes Nb of the second external heat exchanger 3B acting as an evaporator in the heating operation described later. More preferably, the following is set (Na <Nb).

  The number of passes Nb of the second external heat exchanger 3B is such that the length of the pipe between the port 3Ba and the port 3Bb, the flow area of the pipe ( It is set as appropriate in consideration of the pipe inner diameter), the speed of the refrigerant flowing in the pipe, and the like.

As shown in FIGS. 5 and 6, each of the plurality of fins 3 f is provided across the first external heat exchanger 3 </ b> A and the second external heat exchanger 3 </ b> B.
Specifically, the plurality of fins 3f are arranged close to each other in parallel and close to each other. And pipe 3cA (refer to Drawing 4) which is piping of the refrigerant piping path of the 1st outside heat exchanger 3A and pipe 3cB (refer to Drawing 4) which is piping of the refrigerant piping path of the 2nd outside heat exchanger 3B ) Are connected to the plurality of fins 3f so as to penetrate perpendicularly.
Therefore, heat transfer is performed between the first external heat exchanger 3A and the second external heat exchanger 3B via the fins 3f.

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

The refrigeration apparatus 51 described in detail above can be applied to various facilities and apparatuses. For example, it is mounted on the refrigerator car C.
FIG. 8 is a side view showing an example of mounting on the refrigerator car C, and a part thereof is a cut surface.

The internal heat exchanger 5 is disposed in an internal space CV of a container C1 (hereinafter also simply referred to as a storage C1) that is a storage to be maintained at a constant temperature in the refrigerator car C, and performs heat exchange with air in the internal space CV.
An external heat exchanger 3 is disposed outside the container C1 (for example, above the driver's seat), and exchanges heat with the outside air.
Other members are installed outside the container C1, and the installation position is not limited.
For example, the compressor 1 and the accumulator 6 are accommodated in the housing S and installed below the vehicle body. The control unit 31 and the input unit 32 are installed around the driver's seat. In particular, the input unit 32 is disposed in a place where the driver can easily operate.
The power source of the compressor 1 is, for example, a battery or an engine (not shown) of the refrigerator car C.

Next, the operation of the refrigeration apparatus 51 will be described with reference mainly to FIGS. 3 and 7 and FIGS.
The refrigeration apparatus 51 operates in a plurality of modes, that is, cooling operation, heating operation, and external heat exchange in order to keep the temperature in the storage C1 constant based on an instruction from the user via the input unit 32. The defrost operation of the unit 3 and the defrost operation of the internal heat exchanger 5 are selectively executed.

First, the cooling operation and the heating operation will be described.
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 circuit of FIG. 9 and FIG. 10, the piping part where the refrigerant flows is indicated by a thick line, and the flow direction of the refrigerant is indicated by a thick arrow.

(Cooling operation)
As shown in FIG. 11, in the cooling operation, the control unit 31 sets the four-way valve 2 to mode A, the electromagnetic valve 11 to an open state, the electromagnetic valve 13 to a closed state, and the fans FM1 and FM2 to an operating state.
The air blowing directions by the fans FM1 and FM2 in this cooling operation are indicated by arrows DR1 and DR2 in FIG. 9, respectively.

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

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.
In this state, in the external heat exchanger 3, the second external heat exchanger 3B and the first external heat exchanger 3A function integrally as a condenser. That is, the gas refrigerant dissipates heat to the outside air and condenses, and flows into the piping path L5 from the port 3Aa as a high-pressure liquid refrigerant.
Specifically, the refrigerant is all in the gas phase at the port 3Ba serving as the inlet of the second external heat exchanger 3B. As the gas-phase refrigerant flows in the second external heat exchanger 3B, it is heat-exchanged with the outside air to partially condense (liquefy), and the ratio of the liquid refrigerant to the gas refrigerant increases.
Thereby, in port 3Bb used as the exit of 2nd external heat exchanger 3B, most refrigerant | coolants become a gas-liquid mixed refrigerant | coolant of a liquid refrigerant. Here, the ratio of the liquid refrigerant varies depending on the operating conditions.

  Next, the gas-liquid mixed refrigerant that has flowed out of the port 3Bb flows into the first external heat exchanger 3A from the port 3Ab. In the first external heat exchanger 3A, heat is continuously exchanged between the refrigerant and the outside air, and in the port 3Aa serving as the outlet, the refrigerant is almost entirely in a liquid phase at a high pressure.

The volume of the refrigerant decreases due to the phase change of the refrigerant from the gas phase to the liquid phase in the external heat exchanger 3.
In the external heat exchanger 3, the number of passes Na of the first external heat exchanger 3 </ b> A through which the refrigerant whose liquid phase ratio has increased due to volume reduction flows is used as the second external heat through which the refrigerant having a high gas phase ratio flows. The number is less than the number of passes Nb of the exchanger 3B. As a result, the refrigerant flowing in the first external heat exchanger 3A has a higher flow velocity than that when the second external heat exchanger 3B flows as a liquid refrigerant, and the degree of supercooling of the refrigerant is also increased.

The high-pressure liquid refrigerant flowing into the piping path L5 passes through the check valve 10 and enters the liquid receiver 4.
In the liquid receiver 4, an excessive amount of liquid refrigerant corresponding to the operating environment stays.
For example, when the heat load in the storage C <b> 1 is small, the amount of circulating refrigerant is small, and a large amount of liquid refrigerant accumulates in the liquid receiver 4. On the other hand, when the heat load in the storage C1 is large, a large amount of circulating refrigerant is required, so that the amount of liquid refrigerant that accumulates in the liquid receiver 4 decreases.
The liquid receiver 4 has a structure in which the liquid refrigerant flows out when the liquid refrigerant is accumulated.

The liquid refrigerant flowing out of the liquid receiver 4 flows into the piping path L6 because the electromagnetic valve 13 is closed and the electromagnetic valve 11 is opened under the control of the control unit 31.
That is, the liquid refrigerant that has flowed into the piping path L6 passes through the electromagnetic valve 11 and enters the expansion valve 12.
In the expansion valve 12, the liquid refrigerant is expanded. As a result, the liquid refrigerant is a gas-liquid mixed refrigerant in which the pressure and temperature are reduced and vaporization is promoted, and the gas phase and the liquid phase are mixed.
The gas-liquid mixed refrigerant that has flowed 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 internal storage C1 to flow in the direction of the arrow DR2 in FIG.
In this state, the gas-liquid mixed refrigerant exchanges heat with the air in the store C1, and takes heat from the air in the store C1 to completely vaporize to become a gas refrigerant. That is, the internal heat exchanger 5 functions as an evaporator and the inside of the storage C1 is cooled.

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

(Heating operation)
As shown in FIG. 11, in the heating operation, the control unit 31 sets the four-way valve 2 to mode B, the electromagnetic valve 11 to the closed state, the electromagnetic valve 13 to the open state, and the fans FM1 and FM2 to the operating state. .
The blowing direction by the fans FM1 and FM2 in this heating operation is the same constant direction as that in the cooling operation, and is indicated by arrows DR3 and DR4 in FIG. 10, respectively.

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

In the liquid receiver 4, the gas refrigerant pushes out the liquid refrigerant accumulated in the previous cooling operation, and soon fills the liquid receiver 4.
Therefore, the gas refrigerant flows out from the liquid receiver 4 next to the stored liquid refrigerant. The gas refrigerant flowing out of the liquid receiver 4 flows into the piping path L7 because the electromagnetic valve 13 is open and the electromagnetic valve 11 is closed under the control of the control unit 31, and then the internal heat exchanger. 5 flows into.

In the internal heat exchanger 5, the fan FM2 is in an operating state under the control of the control unit 31 as described above, and the air in the internal chamber C1 flows in the direction of the arrow DR4 in FIG.
In this state, the gas refrigerant exchanges heat with the air in the store C1, releases heat to the air in the store C1, condenses, and becomes a generally high-pressure liquid refrigerant. Therefore, the inside of the warehouse C1 is heated.

The refrigerant flowing out of the internal heat exchanger 5 includes a liquid refrigerant and an amount of gas refrigerant corresponding to the operating environment such as a heat load in the storage C1.
The gas-liquid mixed refrigerant including the liquid refrigerant and the gas refrigerant flows into the pipe path L9 because the pressure in the branch portion D3 is lower than that in the branch portion D4. And it flows in into the 1st outside heat exchanger 3A of the outside heat exchanger 3 from port 3Aa through the non-return valve 15.

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 is flowing in the direction of the arrow DR3 in FIG. Therefore, 3 A of 1st external heat exchangers are located in the upstream of the flow of external air with respect to the 2nd external heat exchanger 3B.
In this state, in the first external heat exchanger 3A, the liquid refrigerant is cooled and the temperature is lowered. That is, the first external heat exchanger 3A functions as a supercooling heat exchanger for the liquid refrigerant.
The gas refrigerant that has flowed into the first external heat exchanger 3A together with the liquid refrigerant also becomes almost all liquid refrigerant by this cooling.

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

  The refrigeration apparatus 51 has the following effects in this heating operation.

  Switching between the cooling operation and the heating operation is performed using a four-way valve. In the heating operation, not only the heat energy obtained by the operation of the compressor but also the heat energy obtained from the outside air by the external heat exchanger. Heating is performed. Therefore, a high heating capability can be obtained.

  Switching between the cooling operation and the heating operation is performed only by switching between the four-way valve and the electromagnetic valve, and control based on the measurement result of the pressure sensor or the like is not necessary. Accordingly, the control of the driving operation is simple.

In the second external heat exchanger 3B, the gas-liquid mixed refrigerant exchanges heat to take 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, a part of the heat released from the liquid refrigerant in the first external heat exchanger 3A is transferred to the second external heat exchanger through the fins 3f, and the phase change in the second external heat exchanger It is used as the heat of evaporation.
Thereby, since the evaporation of the liquid refrigerant in the second external heat exchanger is promoted, the so-called liquid back phenomenon in which the liquid refrigerant is sucked into the compressor can be prevented.

Further, even when the driving environment is traveling in a cold region, for example, when snow has landed on the fins 3f due to snowfall, the snow adhering to the fins 3f is not removed from the first external heat exchanger when the fins 3f are heated. It melts because it is warmed by the heat released by heat exchange.
In addition, the portion on the second external heat exchanger 3B side of each of the plurality of fins 3f is warmed by the outside air heated by heat exchange in the first external heat exchanger 3A flowing downstream. The heat given to the fins 3f by heat exchange in the first external heat exchanger 3A is also warmed by transferring it to the downstream side of the fins 3f.
From these, since the whole fin 3f is heated efficiently, accumulation of snow and frost formation on the fin 3f are extremely effectively prevented.
Therefore, the refrigeration apparatus 51 has a long execution interval of the defrost operation, and the operation efficiency is improved.

In this heating operation, the liquid refrigerant does not stay in the liquid receiver 4. On the other hand, the refrigerant circulation amount required for the refrigerant circuit changes according to the operating environment including the heat load in the warehouse C1.
Therefore, in the refrigeration apparatus 51, in the first external heat exchanger 3A, an amount of gas refrigerant corresponding to the operating environment is present together with the liquid refrigerant.
In other words, the first external heat exchanger 3A adjusts and secures the excess liquid refrigerant so that the optimum refrigerant amount circulates in the refrigerant circuit in the refrigerant circuit instead of the liquid receiver 4 in the heating operation. It is supposed to be.
Thereby, the pressure on the high pressure side of the refrigerant circuit can be maintained at a high value.
Therefore, the refrigerant condensing temperature in the internal heat exchanger 5 is increased, and the heating capability is improved.

In the refrigeration apparatus 51, the direction of the refrigerant flowing in the internal heat exchanger 5 is the same in the cooling operation and the heating operation, for example, by using the flow direction regulating unit RK. In addition, the airflow direction generated by the operation of the fan FM2 is the same in the cooling operation and the heating operation.
Moreover, as FIG.9 and FIG.10 shows, the flow direction of the refrigerant | coolant in the in-compartment heat exchanger 5 goes from a downstream side to an upstream side so as to oppose the ventilation direction (arrows DR2, DR4) (inflow from the downstream side). And outflow from the upstream side).
As a result, there is no significant difference between the heat exchange efficiency during the cooling operation and the heat exchange efficiency during the heating operation. Thereby, heat exchange efficiency further improves.

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 liquid receiver 4 during the heating operation, the liquid refrigerant that has accumulated in the liquid receiver 4 during the cooling operation is stored in the first external heat exchanger 3A during the heating operation. The amount is adjusted and secured.
Specifically, the secured amount of liquid refrigerant in the first external heat exchanger 3A is adjusted by changing the vaporization amount of liquid refrigerant (the amount of gas refrigerant).
Regarding the adjustment function of the amount of liquid refrigerant in the first external heat exchanger 3A, the capacity Qa of the liquid refrigerant in the first external heat exchanger 3A is determined from the capacity Qb of the liquid refrigerant in the receiver 4 by experiments. It was concluded that it is desirable to set a value that does not exceed (ie, Qa ≦ Qb).
The adjustment setting of the capacity Qa is performed by, for example, increasing or decreasing the number of rows of the tubes 3c in the first external heat exchanger 3A.
That is, it is assumed that the first external heat exchanger 3A having M rows and N stages has a fixed structure with a predetermined capacity in one row, and M fixed structures are arranged in parallel along the delivery direction of the fan FM1.
At this time, it is desirable that the value of M be the maximum value in a range where the capacity of the first external heat exchanger 3 </ b> A does not exceed the capacity of the liquid receiver 4.

  Next, the defrost operation will be described.

(Defrost operation of internal heat exchanger 5)
When the cooling operation is performed for a long time, moisture contained in the air in the warehouse C1 may freeze and adhere to the fins of the internal heat exchanger 5 as frost. Since the frost formation on the fins hinders heat exchange, the defrost operation of the internal heat exchanger 5 is executed to defrost.
As shown in FIG. 11, the defrost operation is an operation that is different from the heating operation only in stopping the fan FM1 and the fan FM2.

(Defrost operation of external heat exchanger 3)
When the heating operation is performed for a long time, moisture contained in the outside air may freeze and adhere as frost to the fins 3f of the external heat exchanger 3.
In the refrigeration apparatus 51, as described above, accumulation of snow and frost formation on the fins 3f of the external heat exchanger 3 are extremely difficult to occur. However, when the refrigeration vehicle C is run during snowfall, if the snowfall amount is extremely large, clogging occurs between adjacent fins 3f on the windward side of the external heat exchanger 3 (on the first external heat exchanger 3A side). There is also a possibility.
In such a case, since heat exchange is hindered, the defrost operation of the external heat exchanger 3 is performed, and snow melting and defrosting are performed on the fins 3f.
As shown in FIG. 11, the defrost operation is an operation that is different from the cooling operation only in stopping the fan FM1 and the fan FM2.

Specific specifications of the external heat exchanger 3 are set as follows, for example.
Thickness Ea in the front-rear direction of the first external heat exchanger 3A (see FIG. 5): 19.05 mm
Thickness Eb in the front-rear direction of the second external heat exchanger 3B (see FIG. 5): 57.15 mm
Total thickness in the front-rear direction (Ea + Eb): 76.20 mm
Height Ec in the vertical direction (see FIG. 5): 355.6 mm
Effective width in the left-right direction (width of the part through which the wind passes) Ed (see FIG. 5): 1050 mm
Refrigerant piping diameter (outer diameter): φ9.53mm
Refrigerant piping pitch Ee (see FIG. 4): 25.4 mm

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

[During heating operation (external heat exchanger 3 functions at least as an evaporator)]
Endotherm: 2.5kW
Refrigerant flow rate in refrigerant piping: approx. 2.10 kg / min
Flow rate of refrigerant in piping of first external heat exchanger 3A: 0.260 m / s (liquid phase state)
Flow rate of refrigerant in piping of second external heat exchanger 3B: 6.45 m / s (gas phase state)
0.173 m / s (liquid phase state)
Refrigerant temperature at the inlet of the first external heat exchanger 3A: 20 ° C
Refrigerant temperature at the outlet of the first external heat exchanger 3A: 5 ° C

Other specifications of the heat exchanger 3 are set so that the heat radiation amount (4.8 kW in the above example) can be obtained particularly in the cooling operation.
As an example of the setting procedure, first, since the second external heat exchanger 3B functions as a condenser during the cooling operation and functions as an evaporator during the heating operation, the specifications during the cooling operation and the heating operation 3 rows (4 rows for the condenser) and 14 stages and 3 passes are set (step “I”).
Next, for example, Na <Nb, which is a more preferable pass number condition, is adopted, and the pass of the first external heat exchanger 3A is set to 2. Furthermore, M, which is the number of rows, is set to 1 calculated as the maximum value in a range where the capacity of the first external heat exchanger 3A does not exceed the capacity of the liquid receiver 4.
In such a procedure, the specification is set, for example, as one row and 14 stages and two passes (step “b”).

As described above, when the external heat exchanger 3 is snowed on the fins 3f of the first external heat exchanger 3A, the snow can be melted by a heating operation.
The first external heat exchanger 3A has only to release a quantity of heat sufficient to melt snow, and the quantity of heat beyond that is wasted simply by heating the melted water.
Moreover, since snow accumulates over the whole suction surface of the 1st external heat exchanger 3A, it is desired not to melt locally but to disperse the melting region as much as possible over the entire suction surface.
As shown in the specification examples, the refrigerant temperature difference between the inlet and the outlet in the first external heat exchanger 3A is, for example, 15 ° C. (deg).
For example, if the number of passes Na is 1, the inlet is on the upper side and the outlet is on the lower side, the upper side simply has the highest temperature and the lower side has the lowest temperature, and a gentle temperature gradient occurs in the vertical direction.
Therefore, when a melting region and a non-melting region are generated, it is generated by being divided in the vertical direction.

On the other hand, the number of passes Na is set to 2, for example, as in the embodiment, and the area substantially occupied by each pass on the suction surface is provided separately on the upper side and the lower side. Furthermore, it is preferable to provide an inlet for one path on the upper side, an outlet for the other path on the lower side, and arrange an outlet for the upper path and a lower inlet on the central portion in the vertical direction.
In this case, since the temperature gradient in the vertical direction of the suction surface is high-low high-low from the upper side, when there is a melting region and a non-melting region, melting-non-melting-melting-non-melting, Appears twice alternately. Therefore, the melting region is preferably dispersed.
This dispersion is preferable because the larger the number of passes Na, the finer the spread.
Further, the higher the number of passes Na, the higher the temperature range, and the more the range is dispersed. Therefore, it is preferable because useless heat release for heating the melted water is suppressed.
Thereby, the number of passes Na is preferably 2 or more.

  The external heat exchanger 3 and the refrigeration apparatus 51 of the embodiment are not limited to the above-described configuration, and may be modified in a range not departing from the gist of the present invention.

<Modification 1>
In Modification 1, in the refrigerant circuit of the refrigeration apparatus 51, a gas-liquid heat exchanger 17 that performs heat exchange is provided between the upstream piping path L6 and the downstream piping path L8 of the internal heat exchanger 5. Example (refrigeration apparatus 51A) (see FIG. 12). FIG. 12 is a partial circuit diagram mainly showing a portion different from the refrigerant circuit (see FIG. 1) of the refrigeration apparatus 51 in the refrigerant circuit of the refrigeration apparatus 51A.
The gas-liquid heat exchanger 17 is connected between the solenoid valve 11 and the expansion valve 12 with respect to the piping path L6. Moreover, it connects between the internal heat exchanger 5 and the branch part D3 with respect to the piping path | route L8.

In the cooling operation in the refrigeration apparatus 51A, the refrigerant flows in the direction of the arrow through the pipe portion indicated by the thick line shown in FIG.
The liquid refrigerant entering the expansion valve 12 in the cooling operation is cooled by exchanging heat with the gas refrigerant flowing out of the internal heat exchanger 5 in the gas-liquid heat exchanger 17 immediately before it, and the degree of supercooling increases.
Thereby, since the amount of heat taken from the air in the store C1 by heat exchange in the store heat exchanger 5 increases, the ability to cool the store C1 is improved.
Moreover, since the evaporation of the liquid refrigerant in the internal heat exchanger 5 is further promoted, the occurrence of the liquid back phenomenon with respect to the compressor 1 can be prevented.

  On the other hand, in the heating operation, since the liquid refrigerant does not flow through the piping path L6 but flows through the piping path L7, the gas-liquid heat exchanger 17 does not act.

<Modification 2>
Modification 2 is an example in which a plurality of internal heat exchangers are provided for the refrigeration apparatus 51 (refrigeration apparatus 51B). Here, the example provided with the two internal heat exchangers 25A and 25B is demonstrated with reference to FIG. FIG. 13 is a partial circuit diagram mainly showing a different portion of the refrigerant circuit of the refrigeration apparatus 51B from the refrigerant circuit of the refrigeration apparatus 51 (see FIG. 1).

As shown in FIG. 13, in the refrigeration apparatus 51B, the internal heat exchanger 25A including the fan FM25A and the internal heat exchanger 25B including the fan FM25B are arranged in parallel between the liquid receiver 4 and the branch portion D3. It is connected to the.
An 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 side of the expansion valves 22 </ b> A and 22 </ b> B has a single path and is connected to the liquid receiver 4 via the electromagnetic valve 23.
An electromagnetic valve 21A is provided between the heat exchanger 25A and the expansion valve 22A and between the liquid receiver 4.
An electromagnetic valve 21B is provided between the heat exchanger 25B and the expansion valve 22B and between the liquid receiver 4.
On the downstream side of the expansion valves 22A and 22B, the paths are combined into one and connected to the branch portion D3.
The operation of the fan FM25A, the fan FM25B, and the solenoid valve 21A and the solenoid valve 21B is controlled by the control unit 31.

This refrigeration apparatus 51B is mounted, for example, in a refrigeration vehicle including a plurality of warehouses that should be maintained at a constant temperature.
The internal heat exchanger 25 </ b> A and the internal heat exchanger 25 </ b> B are installed so as to cool and warm the interiors of different storages.

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

  According to the second modification, cooling or heating of a plurality of warehouses can be performed independently by combining the open state and the closed state of each electromagnetic valve 21A, 21B, 23. For example, it is possible to cool only a specific unit or a plurality of specific units, or cool all units.

  Modification 1 and Modification 2 can be combined as appropriate.

  Although the flow direction restricting unit RK is not limited to one configured using a plurality of check valves, the flow direction restricting unit RK can be configured at a low cost by using check valves.

<Modification 3>
The modified example 3 is a refrigeration apparatus 57 in which the refrigeration apparatus 51 includes a refrigerant circuit that enables a cooling operation and a heating operation without the flow direction restricting unit RK.
The configuration of the refrigeration apparatus 57 is shown in FIG. 14 which is the refrigerant circuit diagram and FIG. 15 which shows the control system.
That is, the refrigerant circuit of the refrigeration apparatus 57 deletes the flow direction restricting unit RK from the refrigerant circuit of the refrigeration apparatus 51, and the parallel circuit LP2, the solenoid valve 11 and the solenoid valve 13, and the check valve 71 and the check valve, respectively. The parallel circuit LP72 is used instead of the valve 73. The other configuration is the same.

Since this configuration does not include the flow direction restricting unit RK, the direction of the refrigerant flowing in the internal heat exchanger 5 is reversed between the cooling operation and the heating operation.
That is, in the parallel circuit LP72, when the refrigerant flows from the liquid receiver 4 into the internal heat exchanger 5, it flows through the piping path L76, and when the refrigerant flows from the internal heat exchanger 5 to the liquid receiver 4. Is configured to flow through the piping path L77.

The cooling operation and heating operation of the refrigeration apparatus 57 will be described with reference mainly to FIGS.
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, similarly to FIGS. 9 and 10, the piping portion through which the refrigerant flows is indicated by a thick line, and the flow direction of the refrigerant is indicated by an arrow along the piping.

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

The refrigerant that has flowed into the pipe path L5 is at a high pressure and almost all is in a liquid phase.
This liquid refrigerant flows into the parallel circuit LP72 through the liquid receiver 4.
In the parallel circuit LP 72, the liquid refrigerant is allowed only to flow into the piping path L 76 by the check valve 71 and enters the expansion valve 72.
In the expansion valve 72, the liquid refrigerant is expanded. As a result, the liquid refrigerant is a gas-liquid mixed refrigerant in which the pressure and temperature are reduced and vaporization is promoted, and the gas phase and the liquid phase are mixed.
The gas-liquid mixed refrigerant flowing out from 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 internal storage C1 to flow in the direction of the arrow DR72 in FIG.
In this state, the gas-liquid mixed refrigerant exchanges heat with the air in the store C1, and takes heat from the air in the store C1 to completely vaporize to become a gas refrigerant. That is, the internal heat exchanger 5 functions as an evaporator and the inside of the storage C1 is cooled.

The gas refrigerant that has flowed out of the internal heat exchanger 5 flows into the piping path L8.
In the refrigeration apparatus 57, the piping path L8 connects the internal heat exchanger 5 and the port 2d of the four-way valve 2 without branching. Therefore, the gas refrigerant returns from the port 2d of the four-way valve 2 in the mode A to the port 2c, and further to the suction port of the compressor 1 through the accumulator 6.

(Heating operation)
As shown in the table of FIG. 18, in the heating operation of the refrigerator 57, the control unit 31 sets the four-way valve 2 to the mode B and the fans FM1 and FM2 to the operating state.
The blowing direction by the fans FM1 and FM2 in the heating operation is the same constant direction as that in the cooling operation, and is indicated by arrows DR73 and DR74 in FIG. 17, respectively.

As shown in FIG. 17, the high-pressure gas refrigerant discharged from the discharge port of the compressor 1 passes through the port 2a from the port 2a of the four-way valve 2 in the mode B through the port 2d as shown in FIG. Flow into.
In the refrigeration apparatus 57, as described above, the piping path L8 connects the port 2d of the four-way valve 2 and the internal heat exchanger 5 without branching.
Therefore, the gas refrigerant flows into the internal heat exchanger 5 in the direction opposite to that during the cooling operation.

In the internal heat exchanger 5, the fan FM2 is in an operating state under the control of the control unit 31 as described above, and the air in the internal chamber C1 flows in the direction of the arrow DR74 in FIG.
In this state, the gas refrigerant exchanges heat with the air in the store C1, releases heat to the air in the store C1, condenses, and becomes a generally high-pressure liquid refrigerant. Therefore, the inside of the warehouse C1 is heated.

  The liquid refrigerant that has flowed out of the internal heat exchanger 5 passes through the piping path L77 having the check valve 73 of the parallel circuit LP72 and the liquid receiver 4, and then the first external heat of the external heat exchanger 3 by the piping path L5. It flows into the exchanger 3A 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 DR73 in FIG. Therefore, 3 A of 1st external heat exchangers are located in the upstream of the flow of external air with respect to the 2nd external heat exchanger 3B.
In this state, in the first external heat exchanger 3A, the liquid refrigerant is cooled and the temperature is lowered. That is, the first external heat exchanger 3A functions as a supercooling heat exchanger for the liquid refrigerant.
The gas refrigerant that has flowed into the first external heat exchanger 3A together with the liquid refrigerant also becomes almost all liquid refrigerant by this cooling.

The supercooled liquid refrigerant flows out from the port 3Ab of the first external heat exchanger 3A and flows into the piping path L3.
In the piping path L3, the liquid refrigerant passes through the check valve 8 and enters the expansion valve 7.
In the expansion valve 7, the liquid refrigerant is expanded. As a result, the liquid refrigerant is a gas-liquid mixed refrigerant in which the pressure and temperature are reduced and vaporization is promoted, and the gas phase and the liquid phase are mixed.
The gas-liquid mixed refrigerant that has flowed 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 from the port 3Bb takes heat from the outside air by heat exchange with the outside air and evaporates to become a gas refrigerant and flows from the port 3Ba into the piping path L2. . That is, the second external heat exchanger 3B functions as an evaporator.
The gas refrigerant that has flowed into the piping path L2 passes from the port 2b of the four-way valve 2 in the mode B to the port 2c, returns to the suction port of the compressor 1 through the accumulator 6.

  Next, the defrosting operation of the refrigeration apparatus 57 will be described.

(Defrost operation of internal heat exchanger 5)
Also in the refrigeration apparatus 57, when the cooling operation is performed for a long time, moisture contained in the air in the warehouse C1 may freeze and adhere as frost to the fins of the internal heat exchanger 5. Since the frost formation on the fins hinders heat exchange, the defrost operation of the internal heat exchanger 5 is executed to defrost.
As shown in the table of FIG. 18, this defrost operation is an operation that is different from the heating operation only in stopping the fan FM1 and the fan FM2.

(Defrost operation of external heat exchanger 3)
Also in the refrigeration apparatus 57, when the heating operation is performed for a long time, moisture contained in the outside air may freeze and adhere as frost to the fins 3f of the external heat exchanger 3.
In the refrigeration apparatus 57, the operation of the external heat exchanger 3 is the same as that of the refrigeration apparatus 51. Therefore, accumulation of snow and frost formation on the fins 3f of the external heat exchanger 3 are extremely difficult to occur.
However, when the refrigeration vehicle C is run during snowfall, if the snowfall amount is extremely large, clogging occurs between adjacent fins 3f on the windward side of the external heat exchanger 3 (on the first external heat exchanger 3A side). There is also a possibility.
In such a case, the heat exchange is hindered so that the heat exchanger does not function, so that the defrost operation of the external heat exchanger 3 is executed to perform snow melting and defrosting on the fins 3f.
As shown in the table of FIG. 18, the defrost operation is an operation that is different from the cooling operation only in stopping the fan FM1 and the fan FM2.

  The refrigeration apparatus 57 can obtain the following effects particularly in the heating operation.

In the second external heat exchanger 3B, the gas-liquid mixed refrigerant exchanges heat to take 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, a part of the heat released from the liquid refrigerant in the first external heat exchanger 3A is transferred to the second external heat exchanger 3B through the fins 3f, and in the second external heat exchanger 3B. Used as heat of evaporation in phase change.
Thereby, since evaporation of the liquid refrigerant in the second external heat exchanger 3B is promoted, the so-called liquid back phenomenon in which the liquid refrigerant is sucked into the compressor 1 can be prevented.

Further, even when the driving environment is traveling in a cold region, for example, even if snow falls on the fins 3f due to snowfall, the snow adhering to the fins 3f is transferred to the first external heat exchanger 3A by the heating operation of the fins 3f. It melts because it is warmed by the heat released by heat exchange.
In addition, the portion on the second external heat exchanger 3B side of each of the plurality of fins 3f is warmed by the outside air heated by heat exchange in the first external heat exchanger 3A flowing downstream. The heat given to the fins 3f by heat exchange in the first external heat exchanger 3A is also warmed by transferring it to the downstream side of the fins 3f.
From these, since the whole fin 3f is heated efficiently, accumulation of snow and frost formation on the fin 3f are extremely effectively prevented.
Therefore, the refrigeration apparatus 57 has a long execution interval of the defrost operation, and the operation efficiency is improved.

In addition, the first external heat exchanger 3A has a plurality of paths P1 and P2, and each path is a substantially independent region on the suction surface without substantially overlapping in the blowing direction (front-rear direction). Has been placed.
Thereby, since unevenness of the surface temperature of the suction surface is suppressed, the snow adhering to the fin 3f melts without unevenness.

<Modification 4>
The parallel circuit LP1 (see FIGS. 1, 4, 9, and 10) that connects the port 3Ab of the first external heat exchanger 3A and the port 3Bb of the second external heat exchanger 3B is modified. As an example 4, a parallel circuit LP1a without the check valve 8 may be replaced.
FIG. 19 shows the parallel circuit LP1a.

<Other variations>
At least one of the external heat exchanger 3 and the internal heat exchanger 5 is not limited to the above-described fin-and-tube type. For example, a serpentine type or a parallel flow type may be used, and even in this case, the same effect can be obtained.
The case where the external heat exchanger 3 is not a fin and tube type will be described in detail.
First, two serpentine type or parallel flow type heat exchangers are prepared and arranged in parallel in the front-rear direction. And each refrigerant | coolant piping is connected so that one side may function as 3A of 1st external heat exchangers, and the other may function as 2nd external heat exchanger 3B. Furthermore, a plurality of heat exchange fins are attached so as to straddle the refrigerant pipes of the two heat exchangers, and both are integrated.

You may implement the Example mentioned above and each modification in combination as much as possible.
For example, the gas-liquid heat exchanger 17 may be applied to the refrigeration apparatus 57 by combining the first modification and the third modification.
In this case, the portion of the refrigerant circuit shown in FIG. 12 is obtained by replacing the solenoid valve 11 with the check valve 71 and replacing the solenoid valve 13 with the check valve 73.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve, 2a-2d Port 3 External heat exchanger 3A 1st external heat exchanger, 3Aa, 3Ab port 3B 2nd external heat exchanger, 3Ba, 3Bb port 3c pipe | tube, 3f fin 3LA, 3LB Refrigerant piping path 4 Receiving device 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 units 51, 51A, 51B, 57 Refrigeration device C Freezer, C1 warehouse (container), CV internal space D1-D4 Branch G, GA1, GA2, GB3 to GB5 Piping line group FM1, FM2, FM25A, FM25B Fan (blower)
LP1, LP2, LP72, LP1a Parallel circuits L1 to L11, 3LA, 3LB, L76, L77 Piping path Na, Nb Number of paths, P1 to P5 Path Qa, Qb Capacity RA, RB Flow path, RK Flow direction regulating part S Container

Claims (3)

As the external heat exchanger of the refrigeration apparatus having a refrigerant circuit including an internal heat exchanger and an external heat exchanger and capable of selectively performing a cooling operation for cooling the internal space and a heating operation for heating the internal space A heat exchanger for a fin-and-tube refrigeration system used,
A first heat exchanger having a first refrigerant piping path;
A second heat exchanger having a second refrigerant piping path connected in series to the first refrigerant piping path and arranged in parallel to the first heat exchanger;
A plurality of fins provided across both the piping of the first refrigerant piping path and the piping of the second refrigerant piping path;
A blower for blowing air to the first heat exchanger and the second heat exchanger;
With
The piping of the first refrigerant piping path and the piping of the second refrigerant piping path are connected so as to orthogonally pass through the plurality of fins,
The first refrigerant piping path has a plurality of paths with a number of passes Na (Na: integer of 2 or more), and the second refrigerant piping path has a plurality of paths with a number of paths Nb (Nb: integer of 3 or more). The number of passes Na and the number of passes Nb satisfy 2 ≦ Na <Nb,
In the ventilation by the blower, the first heat exchanger is arranged on the upstream side, and the second heat exchanger is arranged on the downstream side,
Each of the plurality of paths of the first refrigerant piping path is disposed as a substantially independent region on the air suction surface of the first heat exchanger,
Each of the plurality of paths of the second refrigerant piping path is disposed as a substantially independent region on the suction surface of the air blowing in the second heat exchanger,
In the cooling operation, after the gaseous refrigerant is condensed in the second heat exchanger, the non-condensed gaseous refrigerant is condensed in the second heat exchanger in the first heat exchanger. And the speed of the condensed refrigerant flowing through the pipe of the first refrigerant piping path is made larger than the speed of the condensed refrigerant flowing through the pipe of the second refrigerant piping path, It functions to increase the degree of supercooling of the condensed refrigerant flowing through the pipe ,
Wherein in the heating operation, the refrigerant liquid, said with Ru said evaporated in the second heat exchanger is made to function as an evaporator after increasing the degree of supercooling in the first heat exchanger, the first Heat released from the liquid refrigerant in the heat exchanger is transmitted to the second heat exchanger via the plurality of fins to promote evaporation of the liquid refrigerant in the second heat exchanger. A heat exchanger for a refrigeration apparatus.   2. The heat for a refrigeration apparatus according to claim 1, wherein in the blowing direction of the blower, the first refrigerant piping path is configured in one row and the second refrigerant piping path is configured in a plurality of rows. Exchanger.   An expansion valve that functions only in the heating operation in which the refrigerant flows from the first refrigerant piping path to the second refrigerant piping path between the first refrigerant piping path and the second refrigerant piping path. The heat exchanger for a refrigeration apparatus according to claim 1 or 2, characterized by comprising:

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