JPH0440114Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an outdoor heat exchanger for a heat pump.

(Prior Art) A refrigerant circuit of a conventional heat pump type air conditioner is shown in FIG.

During cooling operation, high-temperature, high-pressure refrigerant gas discharged from the variable capacity compressor 1 passes through the four-way valve 2 and enters the outdoor heat exchanger 3 as shown by the solid arrow, where it is blown by the outdoor fan 4. By exchanging heat with outside air, it condenses and liquefies, becoming a high-temperature, high-pressure liquid refrigerant. Next, this liquid refrigerant is adiabatically expanded by being throttled by the expansion valve 5 and becomes a gas-liquid two-phase at low temperature and low pressure. Next, this refrigerant enters the indoor heat exchanger 6, where it exchanges heat with the indoor air blown by the indoor fan 7, evaporates and becomes a low-temperature, low-pressure gas refrigerant, and the four-way valve 2 is turned into a gas refrigerant. After that, it returns to compressor 1. Note that during this cooling operation, the two-way electromagnetic valve 9 installed in the bypass circuit 8 is closed.

During heating operation, the four-way valve 2 is switched as shown by the broken line, so the refrigerant discharged from the compressor 1 is transferred to the four-way valve 2, indoor heat exchanger 6, expansion valve 5, and outdoor heat as shown by the two-dot chain arrow. Exchanger 3, four-way valve 2
are returned to the compressor 1 in this order, and the electromagnetic two-way valve 9 is closed.

During defrosting operation, the expansion valve 5 and the electromagnetic two-way valve 9 are opened, so most of the refrigerant discharged from the compressor 1 passes through the bypass circuit 8 and the electromagnetic two-way valve 9, as shown by the broken line. Then, it flows into the outdoor heat exchanger 3 and melts the frost adhering to the outdoor heat exchanger 3. A part of the refrigerant passes through the four-way valve 2, the indoor heat exchanger 6, and the expansion valve 5 in this order, joins with most of the previously branched refrigerant, and returns to the compressor 1 via the indoor heat exchanger 3 and the four-way valve 2. . At this time, a portion of the high-temperature, high-pressure refrigerant gas flows through the indoor heat exchanger 6, so that the indoor air temperature does not drop significantly.

FIG. 2 shows the details of the outdoor heat exchanger 3, and the outdoor heat exchanger 3 has heat exchange tubes 3a and 3b divided into two circuits arranged in roughly two rows in the direction of the flow of outside air as indicated by the white arrows. During cooling operation, the refrigerant is divided into two equal parts into the heat exchange tubes 3a and 3b, one of which is rising from the bottom to the top as shown by the solid arrow, and the second is from the primary side (air inflow side). The other side moves from the secondary side to the primary side. During heating operation and defrosting operation, the refrigerant is divided into two equal parts as shown by the two-dot chain line and the broken line arrow, and descends from top to bottom.

(Problems to be solved by the invention) In the conventional heat pump described above, the frequency of the current supplied to the electric motor that drives the compressor during cooling operation is reduced by an inverter, or the hot gas discharged from the compressor is bypassed. If the capacity of the compressor 1 is reduced by increasing the amount, etc.
The amount of refrigerant circulating decreases and the refrigerant is transferred to outdoor heat exchanger 2.
It becomes impossible to raise the heat from the bottom to the top through the heat exchange tubes 3a and 3b. As a result, the liquid refrigerant gradually accumulates in the outdoor heat exchanger 3, and the amount of refrigerant circulation becomes extremely small. If the operation continues as it is, there is a risk that the compressor will burn out due to an increase in the discharge gas temperature.

Further, when the heating operation is performed at a low outside temperature, frost adheres to the outdoor heat exchanger 3, and the amount of frost adhered to the primary side is larger than that of the secondary side. Therefore, during defrosting operation, if the refrigerant gas is divided into two parts and passed through the heat exchange tubes 3a and 3b in equal amounts to the primary side and the secondary side,
There was a problem where the frost on the primary side remained unmelted.

(Means for solving the problem) The present invention was proposed to solve the above problem, and its gist is to arrange heat exchange tubes divided into multiple circuits in multiple rows. In the outdoor heat exchanger for a heat pump, the circuit is formed into an inverted U-shaped path and arranged in multiple stages in the vertical direction, and the refrigerant inlet side of each path during defrosting operation is arranged on the outside air inflow side. The outdoor heat exchanger for heat pumps is characterized by:

(Function) Since the present invention has the above configuration,
During cooling operation, the refrigerant changes phase from gas to liquid through two phases of gas and liquid as it flows through each circuit, but since each circuit forms an inverted U-shaped path, the inverted U-shaped path In the latter half, the dryness of the refrigerant decreases or becomes a liquid phase, and therefore, even if the amount of refrigerant circulation decreases, the refrigerant is discharged by its own weight. During defrosting operation, high-temperature refrigerant gas flows through the first half of the inverted U-shaped path located on the outside air inflow side, that is, the refrigerant inlet side, so that frost can be reliably melted.

(Example) One embodiment of the invention is shown in FIG.

The outdoor heat exchanger 30 has heat exchange tubes 30a and 30b divided into two circuits, each circuit forming an inverted U shape and arranged in two stages in the vertical direction, and each pass during the defrosting operation. The refrigerant inlet side of the refrigerant is located on the outside air inflow side as indicated by the white arrow. The other configurations are the same as the conventional one shown in FIG.

Therefore, during cooling operation, the refrigerant is transferred to the outdoor heat exchanger 3.
During the process of flowing through the heat exchange tubes 30a and 30b, the dryness decreases or becomes a liquid phase in the descending part of the inverted U-shaped path, reducing the capacity of the compressor. Even when the amount of refrigerant circulating is reduced, the refrigerant is discharged under its own weight.

Furthermore, during defrosting operation, high-temperature refrigerant gas is supplied to the refrigerant inlet side of the first half of the inverted U-shaped path located on the outside air inflow side, so that frost can be reliably melted.

In the above embodiment, the heat exchange tube is divided into two circuits, but it may be divided into two or more circuits, in which case each circuit is arranged in multiple stages in the vertical direction.

(Effects of the invention) In this invention, the circuit is arranged vertically in multiple stages as inverted U-shaped paths, and the refrigerant inlet side of each path during defrosting operation is placed on the outside air inflow side. During operation, even if the amount of refrigerant circulation decreases, the refrigerant is discharged from the outdoor heat exchanger due to its own weight, so it is possible to prevent liquid refrigerant from accumulating in the outdoor heat exchanger. Also, during defrosting operation,
Since the high-temperature refrigerant gas flows on the inflow side of the outside air where there is a large amount of frost, it is possible to completely melt the frost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the circuit path of the outdoor heat exchanger according to the present invention, Fig. 2 is an explanatory diagram showing the circuit path of the conventional outdoor heat exchanger, and Fig. 3 is an explanatory diagram showing the circuit path of the conventional outdoor heat exchanger. It is a refrigerant circuit diagram of. Outdoor heat exchanger...30, heat exchange tube...3
0a, 30b.

Claims (1)

[Scope of utility model registration request] In an outdoor heat exchanger for a heat pump, in which heat exchange tubes divided into multiple circuits are arranged in multiple rows, the circuits are arranged in multiple stages in the vertical direction in an inverted U-shaped path, and during defrosting operation. An outdoor heat exchanger for a heat pump, characterized in that the refrigerant inlet side of each path is arranged on the outside air inflow side.