JP2002286332A - Vapor compression type heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wasteful heat dissipation and further prevent a liquid-back trouble upon returning to an ordinary operation in a defrosting operation of a heat pump that absorbs heat from fresh air. SOLUTION: A heat absorption heat exchanger 3 for forcing fresh air OA to serve to absorb heat is divided to an air upstream side section 3A and an air downstream side section 3B, and changeover is ensured between an ordinary operation where a refrigerant R is circulated in the order of a compressor 1-a heat dissipation heat exchanger 2-an expansion mechanism 5-a parallel connection circuit or a series connection circuit of the air upstream side section 3A and the air downstream side section 3B-the compressor 1, and a defrosting operation for circulating the refrigerant R in the order of the compressor 1-the air upstream side section 3A of the heat absorption heat exchanger 3-the expansion mechanism 5-heat dissipation heat exchanger 2-the compressor 1 in the state that refrigerant passing through the air downstream side section 3B of the heat absorption heat exchanger 3 is interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor compression heat pump that absorbs heat from outside air, and more specifically, in a normal operation, in the order of a compressor, a heat exchanger for heat dissipation, an expansion mechanism, a heat exchanger for heat absorption, and a compressor. The present invention relates to a vapor compression heat pump in which a circulation operation is performed, and in this normal operation, a heat absorbing heat exchanger acts as an evaporator to absorb heat to outside air.

[0002]

2. Description of the Related Art Conventionally, in this kind of vapor compression heat pump, in a heat absorbing heat exchanger in a state of absorbing heat to the outside air in a normal operation, frost due to moisture in the outside air and adhesion of snow contained in the outside air are accumulated. When the defrosting operation (including snow removal) occurs, the refrigerant is switched by a four-way valve or the like to switch the refrigerant path, and the refrigerant is reversed in the normal operation, which is a compressor-heat absorption heat exchanger-expansion mechanism-heat exchange for heat radiation. In this defrosting operation, the heat exchanger for heat absorption functions as a condenser, and the adhering frost and attached snow in the heat exchanger for heat absorption are removed by the heat generated by the condenser. It was melted and removed.

[0003]

However, conventionally, in this defrosting operation, the amount of heat dissipated without effectively contributing to melting of attached frost and attached snow is large among the heat generated as a condenser of the heat absorbing heat exchanger. However, there has been a problem that this wasteful heat dissipation causes a decrease in energy efficiency and an increase in running cost.

[0004] In this defrosting operation, a large amount of liquid refrigerant condensed by refrigerant cooling by adhering frost or adhering snow and refrigerant cooling by outside air is accumulated in a heat absorbing heat exchanger as a condenser. Thus, when returning to the normal operation in which the heat absorbing heat exchanger functions as an evaporator, there is also a problem that a so-called liquid back trouble in which the compressor sucks the liquid refrigerant easily occurs.

[0005] In view of this situation, the main problems of the present invention are:
By adopting a rational refrigerant circulation mode, the above problem is effectively solved while minimizing the complexity of the refrigerant circuit.

[0006]

Means for Solving the Problems [1] The invention according to claim 1 relates to a vapor compression heat pump. The feature of the invention is that a heat absorbing heat exchanger that acts as an evaporator to absorb heat to outside air is provided in an outside air ventilation passage. Divided into a leeward part located on the leeward side and a leeward part located on the leeward side, the refrigerant is divided into a compressor, a heat exchanger for heat dissipation, an expansion mechanism, and a leeward part and a leeward part of the heat exchanger for heat absorption. The parallel connection circuit or series connection circuit of-normal operation in which the compressor is circulated in the order of the compressor, and in the state where the passage of the refrigerant to the leeward part of the heat-absorbing heat exchanger is shut off, the refrigerant flows upwind of the compressor-heat-absorbing heat exchanger. Part-expansion mechanism-
The point is that it is configured to be able to switch to a defrosting operation that circulates in the order of a heat exchanger for heat radiation and a compressor.

In other words, according to this configuration, in the normal operation, the heat radiating heat exchanger functions as a condenser by the above-described refrigerant circulation, whereas the heat absorbing heat exchanger has a parallel-connected or series-connected windward portion. And the leeward portion function as an evaporator, and both the leeward portion and the leeward portion absorb heat from the outside air (that is, the entire heat-absorbing heat exchanger as in the conventional device). An endothermic effect can be made to the outside air as an evaporator).

[0008] In the defrosting operation, the refrigerant circulates in a state where the passage of the refrigerant to the leeward side of the heat-absorbing heat exchanger is blocked, so that the heat-dissipating heat exchanger functions as an evaporator. Only the windward side of the heat exchanger functions as a condenser, and the heat generated at the windward side (heat generated by the condenser) melts and removes attached frost and attached snow. Since frost and snow deposits mainly occur on the windward side in the direction of outside air ventilation, even if only the windward side of the heat absorbing heat exchanger is used as a condenser to generate heat, the normal frost A sufficient defrosting and snow removing effect can be obtained with respect to snow and snow, and the frost and snow attached to the heat absorbing heat exchanger can be effectively melted and removed.

In the defrosting operation, the passage of the refrigerant to the leeward side of the heat absorbing heat exchanger is shut off. Therefore, as described above, frost and snow deposits mainly occur in the windward side of the heat absorbing heat exchanger. In contrast to the conventional device, the entire heat absorbing heat exchanger functions as a condenser in the defrosting operation as in the conventional device. It is possible to prevent wasteful heat dissipation that does not contribute to melting and removal of attached snow, and even if the liquid refrigerant condensed by refrigerant cooling due to attached frost or attached snow accumulates in the heat absorbing heat exchanger, the accumulation will not occur. Since the heat exchanger for heat absorption is limited to the windward side of the heat exchanger, the accumulation of the liquid refrigerant as the heat exchanger for heat absorption as a whole compared to the conventional device that makes the entire heat exchanger for heat absorption function as a condenser The amount can also be greatly reduced

That is, from the above, according to the above configuration, it is possible to effectively improve the energy efficiency and effectively reduce the running cost as compared with the above-described conventional device.
Further, it is possible to more reliably prevent the liquid back trouble at the time of returning from the defrosting operation to the normal operation.

In the defrosting operation, as another operation mode, the leeward portion of the heat-absorbing heat exchanger functions as an evaporator while the leeward portion of the heat-dissipating heat exchanger and the leeward portion of the heat absorbing heat exchanger are used. There is an operation mode in which both are connected in series and function as a condenser (Japanese Patent Laid-Open No. 4-174).
In this case, in the switching between the normal operation in which both the leeward and leeward portions of the heat absorbing heat exchanger function as an evaporator, the upstream side of the heat absorbing heat exchanger circulates the refrigerant. A special circuit switching configuration to move to a different position on the path is required, which complicates the refrigerant circuit structure.

On the other hand, according to the above configuration, in order to perform the defrosting operation, the heat exchange for heat absorption is different from the basic circuit configuration similar to that of the conventional device in which the circulation direction of the refrigerant is simply opposite to the normal operation. It is only necessary to add a simple structure for blocking the passage of the refrigerant to the leeward side of the vessel, and in this respect, the refrigerant circuit structure is simplified and the apparatus cost is reduced as compared with the above-described alternative operation mode. Thus, the effects described above can be obtained.

In the embodiment of the present invention, the number of heat-radiating heat exchangers in the refrigerant circulation path is not limited to one, and the heat-radiating heat exchanger and the defrosting operation in the normal operation are performed. The heat radiation heat exchanger at the time is not necessarily limited to the same heat exchanger.

In the defrosting operation, a heat absorbing heat exchanger (a heat exchanger functioning as an evaporator in a normal operation) different from the heat absorbing heat exchanger to be subjected to defrosting and snow removal is located in the refrigerant circulation path. A circuit configuration may be used.

[2] The second aspect of the present invention specifies a preferred embodiment for carrying out the first aspect of the present invention. The feature of the second aspect is that a refrigerant is supplied to a compressor-wind absorbing heat exchanger. The configuration is such that a strong defrosting operation that circulates in the order of the parallel connection circuit of the upper part and the leeward part, the expansion mechanism, the heat radiation heat exchanger, and the compressor can be switched.

That is, according to this configuration, even if the above-described defrosting operation in which only the windward side portion of the heat absorbing heat exchanger functions as a condenser is performed, the adhering frost or adhering may occur depending on external air conditions at that time. The snow could not be completely removed by melting, and frost would progress to the leeward side of the heat exchanger for heat absorption, or the frost or the melted water of the snow melted on the windward side would move to the leeward side and re-freeze. When the above-mentioned strong defrosting operation is performed, both the leeward side part and the leeward side part of the heat absorbing heat exchanger function as a condenser. Can be melted and removed. In this regard, while the above-described effects are obtained by the invention according to claim 1, the reliability of protection against frost and snow deposition in the heat absorbing heat exchanger is further enhanced. Can be something.

In order to make both the leeward and leeward portions of the heat absorbing heat exchanger function as condensers in the strong defrosting operation, a parallel connection circuit of the leeward portion and the leeward portion as described above. (Ie, the refrigerant is passed in parallel to the leeward part and the leeward part)
Thereby, the refrigerant distribution amount to the leeward side portion and the leeward side portion is automatically adjusted according to the amount of frost and snow attached to each portion (generally, the leeward side portion is more frost and snowy). Since the amount of adhesion is large and the cooling effect on the refrigerant is large, the refrigerant is biased toward the windward portion), whereby the refrigerant passes in series to the windward portion and the leeward portion. Frost and attached snow can be melted and removed more efficiently, and wasteful heat dissipation that does not contribute to the thawing and removal of attached frost and attached snow can be effectively suppressed even in strong defrosting operation. can do.

[3] The invention according to claim 3 specifies an embodiment suitable for carrying out the invention according to claim 1 or 2, and its characteristic is that the capacity of the windward portion is changed to the leeward side. The point is that it is smaller than the capacity of the part.

In other words, according to this configuration, the capacity of the leeward portion functioning as a condenser during the defrosting operation in the heat absorbing heat exchanger is smaller than the capacity of the leeward portion that blocks the passage of the refrigerant during the defrosting operation. By doing so, it is possible to effectively prevent wasteful heat dissipation and reduce the amount of accumulated liquid refrigerant as described above, thereby preventing the useless heat dissipation and reducing the amount of accumulated liquid refrigerant. It is possible to more effectively achieve an improvement in energy efficiency, a reduction in running cost, and a prevention of a liquid back trouble due to the formation of a liquid.

Since the frost and the adhesion of snow in the heat exchanger for heat absorption mainly occur in the windward part in the direction of the outside air, especially in the part near the windward end, the capacity of the windward part is as described above. Even if is slightly smaller than the capacity of the leeward portion, a sufficient defrosting and snow removing effect can be obtained with respect to normal frost and snow adhesion.

[4] The invention according to claim 4 is the invention according to claims 1 to
3. A preferred embodiment for carrying out the invention according to any one of (3) and (3), characterized in that in the normal operation, the refrigerant passes in series to the leeward part and the leeward part in this order in series. The point is that it is configured to be.

That is, according to this configuration, in the defrosting operation, after the condensed liquid refrigerant accumulated in the leeward side of the heat absorbing heat exchanger is switched to the normal operation, the refrigerant is not passed until the normal operation without the refrigerant. The refrigerant can be sucked into the compressor through the leeward portion which becomes a state functioning as an evaporator with the switching, so that the refrigerant is arranged in parallel with the leeward portion and the leeward portion of the heat absorbing heat exchanger in normal operation. Combined with the above-described reduction in the amount of accumulated liquid refrigerant, liquid back trouble at the time of returning from the defrosting operation to the normal operation can be more effectively prevented as compared with the case of adopting the form of passing through the liquid refrigerant.

[0023]

1 shows a refrigerant circuit of a heat pump, 1 is a compressor, 2 is a heat exchanger for heat dissipation, 3 is a heat exchanger for heat absorption, 4 is a four-way valve, 5 is an expansion mechanism, and 6 is an expansion mechanism. A refrigerant guide circuit in which four check valves 6a to 6d are combined in a bridge circuit shape, and 7 is a liquid receiver. Reference numeral 8 denotes a fan that passes outside air OA as a heat absorption source to the heat supply heat exchanger 3.

As shown in FIG. 4, the heat absorbing heat exchanger 3 is constituted by a fin tube coil having a number of heat transfer fins 9 and 10 penetrating a meandering heat transfer tube 3a. The leeward portion 3A having the rows L1 and L2 and the leeward portion 3B having the three rows of heat transfer tube rows L3 to L5 are divided, and these leeward portions 3A and leeward portions 3B are arranged in this order from the leeward side. They are arranged adjacent to each other in the outside air ventilation path F by the fan 8.

As shown in FIG. 1, the leeward portion 3A and the leeward portion 3B are interposed in the refrigerant circuit in a parallel connection state, and the leeward portion 3B is provided in the refrigerant supply / discharge passage for the leeward portion 3B. A shutoff valve V for shutting off the passage of the refrigerant to 3B is provided.

That is, in this heat pump, the following normal operation, defrosting operation, and strong defrosting operation are selectively performed by switching the four-way valve 4 and the shutoff valve V.

(A) Normal operation With the four-way valve 4 switched to the forward direction and the shut-off valve V opened, as shown in FIG. Device 2-refrigerant guide circuit 6-liquid receiver 7-expansion mechanism 5-refrigerant guide circuit 6-parallel connection circuit of leeward side portion 3A and leeward side portion 3B of heat absorbing heat exchanger 3-four-way valve 4
-Circulate in the order of the compressor 1, whereby both the leeward part 3A and the leeward part 3B of the heat exchanger 3 for heat absorption function as an evaporator, and the leeward part 3A and the leeward part 3B Are made to absorb heat to the ventilated outside air OA by the fan 8, while the heat radiating heat exchanger 2 functions as a condenser to generate high-temperature heat in the heat radiating heat exchanger 2.

(B) Defrosting operation FIG. 2 shows a state in which the four-way valve 4 is switched to the reverse direction, and the shutoff valve V is closed to block the passage of the refrigerant to the leeward side portion 3B of the heat absorbing heat exchanger 3. As shown in FIG.
-Four-way valve 4-Upwind side portion 3A of heat exchanger 3 for heat absorption-Refrigerant guide circuit 6-Receptor 7-Expansion mechanism 5-Refrigerant guide circuit 6-
The heat radiating heat exchanger 2-the four-way valve 4-the compressor 1 are circulated in this order, whereby the heat radiating heat exchanger 2 functions as an evaporator, and the heat radiating heat exchanger 2 becomes a heat application target during normal operation. On the other hand, heat is absorbed, and only the windward portion 3A of the heat absorbing heat exchanger 3 functions as a condenser to generate high-temperature heat in the windward portion 3A.

That is, in normal operation in which the heat absorbing heat exchanger 3 absorbs heat to the outside air OA, frost due to moisture in the outside air and adhesion of snow contained in the outside air due to outside air conditions cause heat absorption heat exchanger 3 ( In particular, the defrosting operation is performed at the wind end portion, and at this time, by performing the defrosting operation, the adhering frost and the adhering snow in the heat absorbing heat exchanger 3 are reduced to the windward portion 3A.
Is melted and removed by the heat generated in step (1), and then returns to normal operation.

(C) Strong defrosting operation With the four-way valve 4 switched to the opposite direction and the shut-off valve V opened, as shown in FIG. Upwind portion 3A and downwind portion 3 of heat exchanger 3
Parallel connection circuit with B-Refrigerant guide circuit 6-Receiver 7-Expansion mechanism 5-Refrigerant guide circuit 6-Heat exchanger for heat radiation 2-Four-way valve 4
-Circulate in the order of the compressor 1, thereby causing the heat-radiating heat exchanger 2 to function as an evaporator, causing the heat-radiating heat exchanger 2 to absorb heat to the heat application target during normal operation.
Both the leeward portion 3A and the leeward portion 3B of the endothermic heat exchanger 3 function as condensers,
High-temperature heat is generated in both A and the leeward portion 3B.

That is, even if the above-mentioned defrosting operation is performed,
Depending on the outside air conditions at that time, the attached frost and attached snow cannot be melted and removed, and the frost will continue to the leeward side of the heat-absorbing heat exchanger. When a situation such as re-icing occurs, the strong defrosting operation is carried out to remove the attached frost and attached snow on the windward side portion 3A and the leeward side portion 3B of the heat exchanger 3 for heat absorption. The heat is removed by the heat generated in the portion 3A and the leeward portion 3B, and then the operation is returned to the normal operation.

The strong defrosting operation is carried out for the purpose of melting and removing adhering frost and adhering snow in the heat absorbing heat exchanger 3 as described above. In some cases, it is performed for the purpose of heating the outside air in the exchanger 3.

[Another Embodiment] Next, another embodiment of the present invention will be listed.

In the above-described embodiment, an example has been shown in which the refrigerant R is passed in parallel to the leeward portion 3A and the leeward portion 3B of the heat absorbing heat exchanger 3 in normal operation. Windward part 3 of the heat exchanger 3 for heat absorption
The refrigerant R may be passed in series to the A and the leeward portion 3B, and when this serial passage is adopted, the refrigerant R is passed from the leeward portion 3A to the leeward portion 3B in this order. By doing so, it is possible to more effectively prevent the liquid back trouble when returning from the defrosting operation to the normal operation.

Upwind part 3A of heat exchanger 3 for heat absorption
The capacity ratio (in other words, the row number ratio of the heat transfer tube rows) between the leeward portion 3B and the leeward portion 3B is not limited to the capacity ratio shown in the above-described embodiment, and various changes are possible. In order to prevent the liquid back trouble at the time of return to the upstream side, it is desirable to make the capacity of the leeward portion 3A smaller than the capacity of the leeward portion 3B.
May be larger than the capacity of the leeward portion 3B.

In the above-described embodiment, when the heat absorbing heat exchanger 3 is constituted by a fin tube coil, the heat transfer fins 9 of the windward portion 3A and the heat transfer fins 10 of the leeward portion 3B are separated. This prevents the heat generated in the leeward portion 3A from being dissipated by the heat transfer to the leeward portion 3B in the defrosting operation, thereby preventing wasteful heat dissipation that does not contribute to melting and removing attached frost and attached snow. The effect was enhanced, but in some cases, the leeward part 3A and the leeward part 3B
In addition, the specific structure and heat exchange type of the heat absorbing heat exchanger 3 divided into the windward portion 3A and the leeward portion 3B may be variously changed. Is possible.

The vapor compression heat pump according to the present invention comprises:
It can be used for various applications in various fields such as air conditioning, snow melting, hot water supply and article heating.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing a refrigerant flow in a normal operation.

FIG. 2 is a refrigerant circuit diagram showing a refrigerant flow in a defrosting operation.

FIG. 3 is a refrigerant circuit diagram showing a refrigerant flow in a strong defrosting operation.

FIG. 4 is a partially cutaway perspective view of a heat exchanger for heat absorption.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Heat exchanger for heat radiation 3 Heat exchanger for heat absorption 3A Upwind part 3B Downwind part 5 Expansion mechanism F Outside air ventilation path OA Outside air R Refrigerant

Claims (4)

[Claims] 1. A heat-absorbing heat exchanger acting as an evaporator for absorbing heat to outside air is divided into a windward portion located on the leeward side and a leeward portion located on the leeward side in the outside air ventilation path, and compresses the refrigerant. Heat exchanger for heat dissipation-Expansion mechanism-Parallel connection circuit or series connection circuit of the leeward and leeward parts of the heat exchanger for heat absorption-Normal operation circulating in the order of the compressor and the heat exchanger for heat absorption Defrosting operation is possible, in which the refrigerant is circulated in the order of compressor-heat absorption heat exchanger upwind-expansion mechanism-radiation heat exchanger-compressor in the state of blocking the passage of refrigerant to the leeward side. A vapor compression heat pump with a simple configuration. 2. Switching between strong defrosting operation in which a refrigerant is circulated in the order of a compressor, a parallel connection circuit of an upwind part and a leeward part of a heat exchanger for heat absorption, an expansion mechanism, a heat exchanger for heat radiation, and a compressor. 2. The vapor compression heat pump according to claim 1, wherein the heat pump is configured to be operable. 3. The vapor compression heat pump according to claim 1, wherein the capacity of the leeward portion is smaller than the capacity of the leeward portion. 4. The vapor compression heat pump according to claim 1, wherein in the normal operation, the refrigerant is passed in series to the leeward portion and the leeward portion in this order. .