JP2002221374A - Evaporator placed in ventilation trunk, and heat pump apparatus utilizing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the performance of an evaporator placed in a ventilation trunk and used in a heat pump apparatus. SOLUTION: In the evaporator structure, an unevaporated refrigerant R, which has passed through an expansion valve mechanism 6, is conducted in a heat-transfer pipe 11 from its one end. The refrigerant R is allowed to reside in the pipe in a full state. The pipe 11 is placed in a ventilation trunk f of a heat-source air A in a posture, in which heat-transfer fins 12 attached on the pipe periphery are inclined or made vertical. Further preferably, in the evaporator structure, a drain duct 17 provided with an opening/closing valve 18 is connected to the lower end of the heat transfer pipe 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air evaporator for exchanging heat between a refrigerant and a heat source air in a heat pump device, and a heat pump device using the same.

[0002]

2. Description of the Related Art Since a large air volume (that is, gas air having a large specific volume) is to be subjected to heat exchange in an evaporator for air in a heat pump device, generally, as shown in FIG. A fin tube coil type is adopted in which the heat source air A passes through and the refrigerant R passes through the tube, but conventionally, in this type of evaporator for air, the air after passing through the expansion valve mechanism 6 is not used. In the process of passing the evaporating refrigerant R through the tube in the form of mist-like wet vapor, minute droplets of the moist vapor refrigerant R are evaporated by removing vaporization heat from the heat source air A (a so-called dry evaporator).

[0003]

However, in this dry-type evaporator for air, the heat transfer coefficient of the air-side heat transfer surface is limited to a low value because gas air, which has a lower heat transfer than liquid, is subjected to heat exchange. In addition, the heat transfer surface of the refrigerant side heat transfer surface of the refrigerant side is also limited to the gaseous refrigerant (wet vapor refrigerant) for heat exchange with the heat transfer surface of the refrigerant side inside the pipe. In addition, there has been a problem that the heat transfer rate (K value) as a whole is lowered and the evaporator performance (and the heat collection performance of the heat pump device) is lowered.

In general, a dry type evaporator for air generally has a structure in which a large number of heat transfer tubes are arranged in parallel to secure a large heat transfer area, and a refrigerant to be evaporated is distributed to these heat transfer tubes by a distributor. However, it is technically difficult to distribute the gaseous refrigerant evenly to many heat transfer tubes, and there is a considerable difference in the refrigerant flow rate of each heat transfer tube. In the state in which the overall flow rate of the refrigerant is adjusted so that an appropriate refrigerant dryness is obtained at the outlet of the refrigerant, the heat transfer tube having a low refrigerant flow rate has an excessive heat transfer area with respect to the refrigerant flow rate (that is, the unevaporated refrigerant is removed). A part of the heat transfer area is not effectively used to evaporate)
Due to this, there was a problem that the evaporator performance was further reduced.

[0005] In view of this situation, the main problems of the present invention are:
The point is that the above-mentioned problem is effectively solved by adopting a rational structure.

[0006]

Means for Solving the Problems [1] The invention according to claim 1 relates to an evaporator for air, which is characterized by a heat transfer tube for introducing unevaporated refrigerant passing through an expansion valve mechanism from one end side. The point is that the liquid-phase refrigerant stays in a full state in the pipe, and the heat transfer fins on the outer circumference of the pipe are arranged in the inclined posture or the vertical posture so as to be disposed in the ventilation path of the heat source air.

In other words, according to this structure, a large amount of air can be ventilated by passing the heat source air outside the heat transfer tube while allowing the refrigerant to pass through the heat transfer tube as in the conventional case. However, compared to the dry-type evaporator for air as described above in which the gaseous wet vapor refrigerant passes through the pipe, the presence of the liquid-phase refrigerant that remains in the pipe of the heat transfer pipe in a full state causes
Heat transfer coefficient of refrigerant-side heat transfer surface inside tube (heat transfer coefficient to refrigerant)
Can be kept high.

[0008] Further, in order to make the pipe position in which the liquid-phase refrigerant stays in the heat transfer pipe, the heat transfer fins on the outer circumference of the pipe which are necessary for heat exchange of a large air volume gas having poor heat transfer are inclined. By adopting the pipe position that is vertical, it is possible to prevent the heat transfer coefficient of air from decreasing due to the accumulation of condensed water in the heat source air on the heat transfer fins and to prevent early frosting. In comparison with the dry type evaporator for air, the heat transfer coefficient (K value) as a whole can be effectively improved, and the performance of the evaporator can be effectively improved.

In addition, in the case of the full liquid system in which the liquid-phase refrigerant is retained, it is not necessary to increase the degree of superheating of the refrigerant at the outlet of the evaporator. As compared with the case where the same heat source air is subjected to heat exchange in the evaporator for air, the evaporation temperature can be increased, and from this, the effect of suppressing frost can be expected.

Further, when a large number of heat transfer tubes are arranged in parallel and the refrigerant to be evaporated is distributed to the heat transfer tubes, even if the distribution becomes somewhat uneven, the heat transfer tubes are filled in a full state. Due to the presence of the staying liquid phase refrigerant, the heat transfer area of each heat transfer tube can effectively contribute to the evaporation of the unevaporated refrigerant (that is, the removal of vaporized heat from the heat source air). The performance of the evaporator can be effectively improved as compared with the evaporator for air.Furthermore, in the conventional dry-type evaporator for air, the gaseous wet vapor refrigerant is equally distributed to each heat transfer tube as much as possible. This eliminates the need for a distributor having a complicated structure and a high manufacturing precision, which are required for the above-described method, and can reduce the apparatus cost.

In the invention according to the first aspect, the liquid-filled state is a state in which at least a part of the heat transfer tube located in the ventilation path of the heat source air in the longitudinal direction of the tube is completely filled with the staying liquid phase refrigerant. (In other words, the state in which the liquid level of the staying liquid-phase refrigerant extends over the entire cross section of the tube), and it is not always necessary that the inside of the heat transfer tube be filled with the staying liquid-phase refrigerant over the entire length of the heat transfer tube.

[2] The invention according to claim 2 specifies an embodiment suitable for carrying out the invention according to claim 1, and the feature thereof is that a non-evaporated refrigerant is introduced into an upper end portion in a vertical posture. The heat transfer tube on the outward path to which the path is connected, and the heat transfer tube on the return path to which the evaporative refrigerant outlet path is connected in the vertical position at the upper end in a vertical position, with their lower end portions communicating with each other. Is located in the horizontal ventilation path.

In other words, in this configuration, the unevaporated refrigerant is supplied to the heat transfer tube on the outward path from the upper end of the heat transfer tube through the introduction path, so that the heat transfer tubes on the forward path and the return path on the forward path and the return path with the lower ends communicating with each other. In the pipe, a full-stagnation portion of the liquid-phase refrigerant is formed in the same retention form as the so-called water trap in the U-trap, and the refrigerant is heated by the ventilating heat source air outside the pipe, and the return path in the full-stagnation portion is formed. The evaporative refrigerant boiling from the liquid surface on the side of the heat transfer tube is sent to the outlet path.

In other words, according to this configuration, the overall configuration of the evaporator is formed by a so-called U-shaped tube shape in which the forward heat transfer tube and the backward heat transfer tube are placed in a vertical posture and their lower ends communicate with each other. While being compact, a large heat transfer area (in other words, the peripheral area of the liquid-phase refrigerant retaining portion) that effectively contributes to the evaporation of the unevaporated refrigerant can be ensured. Combined with the effects described above,
A more excellent evaporator for air can be obtained which can obtain a large heat collection amount (heat absorption amount) while being compact.

[3] The invention according to claim 3 specifies an embodiment suitable for carrying out the invention according to claim 1 or 2, and the feature of the invention is that a large number of the heat transfer tubes are connected to each other. Are arranged in parallel with a space between them, and the parallel group of heat transfer tubes is arranged in a state of crossing the air passage with respect to the ventilation passage of the heat source air.

That is, according to this configuration, the heat transfer area for the ventilation heat source air can be effectively expanded by the parallel arrangement of a large number of heat transfer tubes as described above, whereby a larger heat absorption (heat absorption) is achieved. Can be obtained efficiently.

By adopting a configuration in which a plurality of the above-described heat transfer tube parallel groups arranged in a state of crossing the air passage are juxtaposed in the direction in which the heat source air is passed, the heat transfer area for the wind heat source air can be expanded more effectively. .

[4] The invention according to claim 4 is the invention according to claims 1 to
A third embodiment of the present invention specifies a preferred embodiment for implementing the invention according to any one of the first to third aspects, and is characterized in that a drainage path including an on-off valve is connected to a lower end portion of the heat transfer tube. .

That is, according to this configuration, when frost due to moisture in the heat source air is generated on the outer surface of the heat transfer tube, which is the air-side heat transfer surface, the liquid refrigerant remaining in the tube is transferred by opening the on-off valve. With the gas discharged from the heat pipe, a hot gas for defrosting (gas-phase refrigerant discharged from the compressor) can be sent into the heat transfer pipe, thereby allowing the liquid-phase refrigerant to stay in the heat transfer pipe. Also, when defrosting is required, defrosting with hot gas can be efficiently performed without hindering the staying liquid phase refrigerant.

[5] The invention according to claim 5 relates to a heat pump apparatus using the evaporator for air according to claim 4,
Its features are: a normal refrigerant circulation that sends the unevaporated refrigerant that has passed through the expansion valve mechanism to the heat transfer tube, and a defrosting refrigerant circulation that sends the refrigerant discharged from the compressor to the expansion valve mechanism through the heat transfer tube. A switching valve for switching a circulation path is provided, the other end of the drain path is connected to a receiver in a refrigerant circuit, and the switching valve is automatically opened when switching from normal refrigerant circulation to defrost refrigerant circulation. That is, a control means is provided.

That is, in this configuration, when frost is formed on the outer surface of the heat transfer tube due to moisture in the heat source air, the refrigerant circulation is switched from the normal refrigerant circulation to the defrosting refrigerant circulation by the switching valve, thereby discharging the compressor. The refrigerant (hot gas) is supplied to the heat transfer tube to perform defrosting. At the time of this switching, the liquid refrigerant remaining in the heat transfer tube passes through the drain passage in the refrigerant circuit by the automatic opening of the on-off valve by the control means. Is discharged to the receiver.
By supplying the refrigerant discharged from the compressor to the heat transfer tubes from which the retained liquid-phase refrigerant has been discharged, efficient defrosting is performed as described above.

That is, according to this configuration, the defrosting can be performed in a state in which the defrosting is reliably performed by the automatic discharge of the staying liquid-phase refrigerant by the automatic opening of the on-off valve as described above. Can be reliably and effectively reduced, and the operation efficiency of the heat pump device can be increased.

When the connection port of the drainage passage to the heat transfer tube is located between the refrigerant inlet and the refrigerant outlet of the evaporator during the circulation of the defrosting refrigerant, the above-mentioned on-off valve is operated when the staying liquid phase refrigerant is completely discharged. If the valve is automatically closed in the evaporator, the compressor discharge refrigerant supplied to the heat transfer tube by the defrosting refrigerant circulation is prevented from leaking to the drainage path by the automatic closing of the on-off valve. Can be surely spread from the refrigerant inlet to the refrigerant outlet, thereby making the defrosting by the refrigerant (hot gas) discharged from the compressor more reliable and efficient.

It is preferable to use a receiver located at the outlet of the condenser in the circulation of the defrosting refrigerant as a receiver to which the staying liquid-phase refrigerant is discharged. An accumulator located in the suction passage of the machine may be used.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a snow melting device using a heat pump, 1 is a heat exchanger for snow melting installed at a snow melting target place such as a road surface, and 2 is an outdoor using external air A (atmospheric air) as a heat source. The heat pump device 2 is an installation package type. The heat pump device 2 includes a compressor 3, a load heat exchanger 4,
The main components are a refrigerant guide circuit 8 in which an air heat exchanger 5, an expansion valve mechanism 6, a four-way valve 7, four check valves 8a to 8d are combined in a bridge circuit, and a receiver 9 (liquid receiver). A refrigerant circuit HP (refrigeration circuit) of a vapor compression type is provided.

The four-way valve 7 switches between the normal refrigerant circulation and the defrosting refrigerant circulation. In the normal refrigerant circulation, as shown in FIG. Heat exchanger 4-refrigerant guide circuit 8-receiver 9-expansion valve mechanism 6-refrigerant guide circuit 8-air heat exchanger 5-four-way valve 7-compressor 3 4
Function as a condenser C, whereas the air heat exchanger 5 functions as an evaporator E (that is, an air evaporator).

In the circulation of the defrosting refrigerant, as shown in FIG. 2, the refrigerant R is conveyed in reverse to the compressor 3-four-way valve 7-air heat exchanger 5-refrigerant guide circuit 8-receiver 9-expansion valve mechanism 6-. The refrigerant is circulated in the order of the refrigerant guide circuit 8-the load heat exchanger 4-the four-way valve 7-the compressor 3, whereby the air heat exchanger 5 functions as the condenser C, whereas the load heat exchanger 4 Function as an evaporator E.

Numeral 10 designates a heat medium L such as brine between the snow melting heat exchanger 1 and the load heat exchanger 4 by the circulation pump P1.
Is a heat medium circulating path for circulating air through the outside air A as heat source air to the air heat exchanger 5.

In other words, in this snow melting apparatus, by circulating the normal refrigerant under the operation of the fan 5a, the air heat exchanger 5 is made to function as an evaporator, and heat is collected from the outside air A by the air heat exchanger 5. The load heat exchanger 4 is caused to function as a condenser, and the heat medium L to be fed to the snow melting heat exchanger 1 is heated by the load heat exchanger 4, thereby melting the snow at the snow melting target portion.

When frost occurs due to moisture in the outside air in the air heat exchanger 5 serving as an evaporator, the refrigerant circulation is switched from the normal refrigerant circulation to the defrosting refrigerant circulation, so that the heat exchange with the load is reduced. The heat exchanger L functions as a condenser while the heat exchanger L functions as a condenser while the heat exchanger L functions as an evaporator to collect heat from the heat medium L. The heat exchanger 5 is defrosted.

As shown in FIGS. 3 and 4, the air heat exchanger 5 which normally functions as an air evaporator in the circulation of the refrigerant includes a parallel group D1 of heat transfer tubes on the outward path and a parallel group D2 of heat transfer tubes on the return path. Are arranged in parallel in a face-to-face state, and the two heat transfer tube parallel groups D1 and D2 are arranged by arranging a large number of straight tubular heat transfer tubes 11 in parallel in a parallel posture in which an interval is provided between adjacent tubes. , Plate-shaped heat transfer fins 1 extending over the parallel heat transfer tubes 11
2 are arranged in the tube core direction and are provided on the outer peripheral surface of the heat transfer tube 11.

The heat transfer tubes 11 in the heat transfer tube parallel group D1 on the outward path and the heat transfer tubes 11 in the heat transfer tube parallel group D2 on the return path are connected to a common intermediate header tube 13 having a position along the heat transfer tube parallel direction. The heat transfer tubes 11 are connected to each other and communicate with each other through the intermediate header tube 13 on one end side (lower end side). On the other hand, the other end (upper end) of each heat transfer tube 11 in the heat transfer tube parallel group D1 on the outward path is parallel to the heat transfer tube parallel direction. Introductory header tube 1 along the posture
4, and the other end (upper end) of each heat transfer tube 11 in the heat transfer tube parallel group D2 on the return path is connected to a lead-out side header tube 15 also in a posture along the heat transfer tube parallel direction.

Then, the air-to-air heat exchanger 5 having this structure is
A state in which both the heat transfer tube parallel groups D1 and D2 cross the ventilation path f of the outside air A in an inclined surface position with the intermediate header tube 13 at the bottom (that is, the heat transfer tubes 11 The heat transfer fins 12 are arranged in an inclined posture (in a state where the heat transfer fins 12 are in an inclined posture). The refrigerant passage for introducing the refrigerant into the air heat exchanger 5) is connected to the introduction-side header pipe 14, and the refrigerant outlet passage 16o to the four-way valve 7 (that is, evaporation in the air heat exchanger 5 in the normal refrigerant circulation). The outlet side header tube 1 is connected to a refrigerant passage through which the refrigerant is discharged from the air heat exchanger 5).
5 is connected.

In other words, with this structure, in the ordinary refrigerant circulation in which the air heat exchanger 5 is used as the evaporator for air, the heat transfer tubes 11 of the parallel group D1 of heat transfer tubes on the outward path are connected to the refrigerant introduction path from their upper ends. In contrast to the supply of the non-evaporated refrigerant R through 16i, the liquid-phase refrigerant R fills up in the forward and backward heat transfer tubes 11 that communicate with each other in the same manner as water sealing in a so-called U trap. The liquid stagnation portion RX is formed, thereby ensuring a high heat transfer coefficient of the heat transfer surface on the refrigerant side of each heat transfer tube 11 (heat transfer coefficient with respect to the refrigerant).

Further, the heat transfer tube 11 is placed in such a position that the liquid refrigerant R full liquid retaining portion RX is formed in the heat transfer tube 11.
When the heat transfer fins 12 are arranged as described above, the heat transfer fins 12 on the outer circumference of the heat transfer tube adopt a pipe posture in which the heat transfer fins 12 are inclined. This prevents the heat transfer coefficient to the air from lowering due to the condensed water pool at 12 and the early frosting of the heat exchanger to the air 5 as an evaporator for the air.

Reference numeral 17 denotes the intermediate header tube 1 of the air heat exchanger 5.
A drain passage 18 extending from the base 3 to the receiver 9 below is an on-off valve interposed in the drain passage 17 and switches the refrigerant circulation from the normal refrigerant circulation to the defrosting refrigerant circulation to provide an air heat exchanger. When defrosting 5 is performed, by opening the on-off valve 18, the liquid-phase refrigerant R staying in the heat transfer tube 11 of the air heat exchanger 5 is transferred to the receiver 9 by gravity through the drainage passage 17. It is designed to discharge quickly.

Reference numeral 19 denotes a controller for controlling the operation of the heat pump device 2. When frost occurs in the air heat exchanger 5, the controller 19 controls the four-way valve 7 based on the detection of frost by the detecting means. Automatic switching from normal refrigerant circulation to defrost refrigerant circulation by switching
At the time of the switching, switching control for automatically opening the on-off valve 18 for a set time is performed.

That is, by temporarily opening the on-off valve 18 at the time of switching from the normal refrigerant circulation to the defrosting refrigerant circulation, the refrigerant stays in the heat transfer tube 11 of the air heat exchanger 5. The liquid refrigerant R, which has been discharged, is quickly discharged to the receiver 9 as described above, and the compressor discharge refrigerant R (hot gas) supplied for defrosting is smoothly introduced into the air heat exchanger 5. From the side of the outlet path 16o to the air heat exchanger 5
The refrigerant discharged to the compressor R is supplied to the outlet-side heat transfer tube 11 which is the outlet side by closing the on-off valve 18 after discharging the retained liquid-phase refrigerant R, so that the compressor Defrosting by the discharged refrigerant R can be performed reliably and efficiently.

[Another Embodiment] Next, another embodiment will be described.

The heat transfer tube 11 for introducing the unevaporated refrigerant that has passed through the expansion valve mechanism from one end side is filled with the liquid-phase refrigerant R in the tube, and the heat transfer fins 12 on the outer periphery of the tube are inclined. Alternatively, the specific structure is not limited to the structure shown in the above-described embodiment, and various changes are possible. Such a structure may be adopted.

As shown in FIGS. 5 and 6, a plurality of heat transfer tubes 1 are provided.
The heat transfer fins 12 are arranged in parallel in an oblique vertical position in which the heat transfer fins 12 are inclined, and the lower ends of these heat transfer tubes 11 are connected to the header pipe 14 on the unevaporated refrigerant introduction side, and the upper ends are connected to the evaporative refrigerant discharge side. And the heat transfer tube parallel group D is arranged in a state of crossing the air passage f with the air passage f of the heat source air A. The heat transfer tubes 11 may be inclined in the direction parallel to the heat transfer tubes 11 instead of the direction inclined to the direction orthogonal to the parallel direction of the heat transfer tubes 11 as shown in FIG. .

As shown in FIG. 7, a plurality of heat transfer tubes 1 attached to the outer periphery of the tube with the heat transfer fins 12 inclined with respect to the tube core.
1 are arranged in parallel in a vertical position, and these heat transfer tubes 11
Is connected to the header pipe 14 on the unevaporated refrigerant introduction side, and the upper end is connected to the header pipe 15 on the evaporative refrigerant outlet side. Make the structure arranged in the state. The heat transfer fins 12 may be inclined in the direction parallel to the heat transfer tubes 11 in the direction parallel to the direction perpendicular to the direction in which the heat transfer tubes 11 are parallel as shown in FIG. Good.

As shown in FIGS. 8 and 9, a plurality of U-shaped heat transfer tubes 11 are arranged in parallel so that the heat transfer fins 12 are in a vertical position or an inclined position. Is connected to the header pipe 14 on the unevaporated refrigerant introduction side, and the other end is connected to the header pipe 15 on the evaporative refrigerant outlet side, and the parallel group D of the U-shaped heat transfer tubes 11 is connected to the ventilation path f of the heat source air A.
To the structure arranged in.

As shown in FIG. 10, a plurality of heat transfer tubes 11 are vertically arranged in parallel in a horizontal position in which the heat transfer fins 12 are in a vertical position, and one end of each of the horizontal heat transfer tubes 11 is connected to the unevaporated refrigerant introduction side. Connected to the vertical attitude header pipe 14, the other end is connected to the vertical attitude header pipe 15 on the evaporative refrigerant outlet side, and the heat transfer tube parallel group D is arranged in the ventilation path f of the heat source air A.

In the above-described embodiment, the refrigerant R is passed through the same expansion valve mechanism 6 in the normal refrigerant circulation and the defrosting refrigerant circulation. A refrigerant circuit structure that allows the refrigerant R to pass through the expansion valve mechanism 6 may be used. In addition, the specific structure of the refrigerant circuit is not limited to the structure described in the above-described embodiment, and various configuration changes are possible.

The heat source air A is not limited to outside air, but may be air discharged from various facilities, air preheated by utilizing solar heat, or indoor air for cooling.

The evaporator for air according to the present invention can be applied to either a heat pump device used for heat application or a heat pump device used for cold application.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus configuration of a snow melting apparatus and a refrigerant flow in a normal refrigerant circulation.

FIG. 2 is a diagram showing a refrigerant flow in a defrosting refrigerant circulation.

FIG. 3 is a side view of an evaporator for air (heat exchanger).

FIG. 4 is a perspective view of an evaporator for air (heat exchanger).

FIG. 5 is a side view showing another embodiment.

FIG. 6 is a perspective view showing another embodiment.

FIG. 7 is a side view showing another alternative embodiment.

FIG. 8 is a side view showing another alternative embodiment.

FIG. 9 is a perspective view showing another alternative embodiment.

FIG. 10 is a perspective view showing another alternative embodiment.

FIG. 11 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 6 expansion valve mechanism 7 switching valve 9 liquid receiver 11 heat transfer pipe 12 heat transfer fin 16i introduction path 16o outlet path 17 drain path 18 on-off valve 19 control means A heat source air D1, D2 heat transfer pipe parallel group f ventilation path R refrigerant

Claims (5)

[Claims] 1. A heat transfer tube for introducing unevaporated refrigerant that has passed through an expansion valve mechanism from one end side, wherein a liquid-phase refrigerant stays in a full state in the tube, and heat transfer fins on the outer periphery of the tube have an inclined posture or An evaporator for air that is arranged in a ventilation path for heat source air in a vertical pipe attitude. 2. The heat transfer tube on the outward path, which has a vertical position and a non-evaporating refrigerant introduction path connected to the upper end at the upper end, and the heat transfer tube on the return path which has a vertical position and a discharge path for the evaporated refrigerant connected to the upper end. The evaporator for air according to claim 1, wherein the lower end and the upper end of the evaporator are arranged in a horizontal ventilation path of the heat source air. 3. A plurality of said heat transfer tubes are arranged in parallel with an interval provided between adjacent ones, and the heat transfer tube parallel group is arranged in a state of crossing the air passage of the heat source air. The evaporator for air according to claim 1 or 2, wherein: 4. The evaporator for air according to claim 1, wherein a drainage passage having an on-off valve is connected to a lower end of the heat transfer tube. 5. A heat pump apparatus using the evaporator for air according to claim 4, wherein a normal refrigerant circulation for sending the unevaporated refrigerant having passed through the expansion valve mechanism to the heat transfer tube, and a refrigerant discharged from the compressor. And a switching valve for switching the circulation path of the refrigerant is provided to the defrosting refrigerant circulation that sends the refrigerant to the expansion valve mechanism through the heat transfer tube. The other end of the drainage path is connected to a receiver in the refrigerant circuit, A heat pump device provided with control means for automatically opening the on-off valve when switching from circulation to defrost refrigerant circulation.