JPS5854346B2 - Heat exchanger for refrigerant evaporation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used for a refrigerant evaporation heat exchanger, specifically an outdoor heat exchanger of an air-cooled heat pump type air conditioner, to evaporate the refrigerant by exchanging heat with outdoor air during heating, The present invention also relates to a refrigerant evaporation heat exchanger that evaporates refrigerant by exchanging heat with the air inside a low-temperature freezer.

Generally, this type of heat exchanger frosts when the temperature of the outdoor air or the air inside the refrigerator decreases, and defrosting at the time of frosting involves reversing the flow of the refrigerant and introducing high-temperature gas into the heat exchanger. This is done by flowing refrigerant.

By the way, the cooling pipes of the heat exchanger are usually arranged horizontally and in multiple stages vertically, and are connected to the liquid pipes via a flow divider, and are connected to the gas pipes via a header. is connected to.

Therefore, when acting as an evaporator, the liquid refrigerant is almost equally divided into the cooling pipes forming each pipe line via the flow divider.

On the other hand, during defrost operation, the high-temperature gas refrigerant flows through the ladder into the cooling pipes forming the respective pipes and condenses, but the liquid refrigerant condensed in the lower cooling pipes flows into the upper cooling pipes. Compared to that, it is difficult for the refrigerant to flow out due to the height difference, and it accumulates instead of flowing into the flow divider, making it difficult for the refrigerant to flow to the lower cooling pipe relative to the upper cooling pipe, resulting in uneven flow. There was a problem in that it took time to defrost the frost that had adhered to the cooling pipes, increasing the overall defrosting time.

On the other hand, the fan attached to the heat exchanger is generally installed above the heat exchanger, but for example, if the fan is placed above, the wind speed in the lower cooling pipes is slow due to the wind speed distribution. As a result, heat exchange is poor (easier to frost) compared to higher wind speeds.

Therefore, when the wind speed of the lower cooling pipe is slow, the amount of frost formed in the lower part increases, and this, combined with the above-mentioned causes, requires a longer defrost time and a need to increase the number of defrosts. There is.

The present invention was invented in view of the above-mentioned problems, and its main purpose is to provide an evaporative heat exchanger that can shorten the defrost time by eliminating the formation of liquid pools in the lower cooling pipes during defrosting. Another purpose is to provide an evaporative heat exchanger that can reduce frost formation in the lower cooling pipes even when the wind speed in the lower cooling pipes is slow and the heat exchange in the lower cooling pipes is poor. The point is to provide the following.

That is, the present invention divides the cooling pipe in the stage direction into a plurality of flocks, and connects one end of each upper block, excluding the lowest block, to the diverting side of the flow divider, and the other end to the gas pipe. and the lowest block is connected to the confluence side of the flow divider via a connecting pipe without an expansion mechanism, and the other end is connected to the expansion mechanism via a liquid pipe. In the case of evaporation,
After the liquid refrigerant flows directly into the cooling pipe of the lowest block, it is diverted to the upper block via a flow divider pipe, and during defrosting, the liquid refrigerant condensed in the cooling pipe of the upper block is collected by the flow divider. After that, the entire amount was made to flow into the cooling pipe of the lowest block.

Therefore, when performing the evaporation action, frost formation in the cooling pipes of the lowest block can be reduced, while during defrosting, there is no filtrate pool in the cooling pipes of the lowest block, and heat exchange by the liquid pool is possible. This eliminates the deterioration of the air conditioner and makes it possible to shorten the defrost time.

Embodiments of the heat exchanger of the present invention will be described below based on the drawings.

The drawing shows an outdoor heat exchanger in an air-cooled heat pump type air conditioner, that is, a heat exchanger that exchanges heat with outdoor air and functions as a condenser during cooling and as an evaporator during heating, as shown in Figure 5, which shows the refrigerant piping system. An example of application to a container is shown.

The air conditioner shown in FIG. 5 is an air-cooled heat pump type air conditioner, and includes an indoor heat exchanger 1 that serves as an evaporator during cooling and a condenser during heating, an indoor fan 2, and an expansion mechanism 3 for cooling. An indoor unit (A) in which the expansion mechanism 3 and a reversal valve 4 installed in parallel, a compressor 5, a four-way switching valve 6, the outdoor heat exchanger 7, an outdoor fan 8, a heating expansion mechanism 9, It consists of an outdoor unit (B) in which a reversal valve 10, a liquid receiver 11, and an accumulator 12 are installed in parallel with the expansion mechanism 9. These devices are connected to each other by piping as shown in FIG. By the switching operation, the flow of the refrigerant is made reversible, forming a cooling cycle indicated by a dotted line arrow and a heating cycle indicated by a solid line arrow, and the indoor heat exchanger 1 evaporates or condenses the refrigerant, thereby providing cooling and heating. It is designed to allow you to drive.

The outdoor heat exchanger 7 is formed into a U-shape when viewed from above as shown in FIG.
The cooling pipes 20 constituting the cooling pipes 20 have a U-shaped hairpin shape, are oriented horizontally, are arranged in multiple stages vertically, and are arranged horizontally in two rows.

Therefore, the present invention is applied to the heat exchanger 7 configured as described above, and as shown in FIG. 3, the cooling pipes 20 in the stage direction are divided into a plurality of blocks 21 to 26, and One end side of each cooling pipe 20 in the upper blocks 21 to 25 except for 26 is connected to the diverter side of the flow divider 300 via the branch pipe 31, and the other end is connected to the gas pipe via each branch pipe 32 and the header 40. 15, and one end side of the cooling pipe 20 in the lowest block 26,
The flow divider 30 is connected to the flow divider 30 via a communication pipe 33 that does not have an expansion mechanism.
0 confluence side, and the other end is connected to the liquid pipe 14 of the air conditioner.
It is connected to the heating expansion mechanism 9 via.

Note that the header 40 is connected to the gas pipe 15 of the air conditioner.
That is, it is connected to the gas pipe 15 through which high-pressure gas refrigerant flows during cooling operation, and through which low-pressure gas refrigerant flows during heating operation.

The one shown in the third diagram has the cooling pipe 20 arranged six times in the direction of the stages.
Divided into blocks 21 to 26, the first block 21 at the top
The pipe line uses the two cooling pipes 20, each bent part of which is supported on the right side tube plate 71, the open end is supported on the left side tube plate 72, and one opening of the two cooling pipes 20 is supported. The ends are connected by a diagonal bend pipe 73, and the other open end of the upper cooling pipe 20 is connected to the header 40 via the branch pipe 32, and is connected to the header 40 located lower. cooling pipe 20
is connected to the flow divider 30 via the flow divider pipe 31, and the pipe lines of the second to fifth blocks 22-25 are formed using three cooling pipes 20, and each bent The section is supported on the right side tube plate 71 like the first block, and also connects the open end of the intermediate section of the open ends supported on the left side tube plate 72 to the oblique bend pipe 74 and the vertical direction. bend pipe 75
The upper open end is connected to the header via the branch pipe 32, and the lower open end is connected to the flow divider 30 via the branch pipe 31.

The sixth block 26 at the lowest level has one cooling pipe 2.
0, its bent part is supported on the right tube sheet 71, and the upper open end of the open ends supported on the left tube sheet 72 is connected to the flow divider 300 through the communication pipe 33. The opening end located on the diversion side and lower part is connected to the liquid pipe 14.
is connected to.

In FIG. 3, the diagonal bend pipes 73 and 74 are used because the above-mentioned combinations of cooling pipes 200 are arranged symmetrically in each block, and the cooling pipes 20 are arranged in two rows in the horizontal direction. This is for the purpose of

In FIG. 3, one set in the column direction is omitted in order to make the combination configuration easier to understand.

In addition, in the case of a two-row configuration, the lowest sixth block 26
Because of the array, two cooling pipes 20 are used in total, and as shown in FIG. 4, each of these two cooling pipes 20 has an oblique bend pipe 76.
It is preferable to provide a pipe 77 to connect the open 1'' ends of each pipe, and connect the communication pipe 33 and the liquid pipe 14 to the bend pipe 7677.

Further, the installation position of the flow divider 30 in the height direction is approximately at the same height as the fifth block 25, as shown in FIGS. 1 and 3.

In this way, the liquid refrigerant condensed in the cooling pipes 20 forming the respective pipes of the first to fifth blocks 21 to 25 is smoothly discharged to the flow divider 30 during defrosting.

Note that even if the flow divider 30 is provided above the above example, the condensed liquid refrigerant can theoretically be discharged due to the siphon action in the same way as in the example, but according to experimental results, the flow divider 30 Since this affects the siphon action and slightly obstructs the discharge of the liquid refrigerant from the cooling pipe 20 of the lower block, it is preferable to arrange it as in the embodiment.

In the above configuration, when the four-way switching valve 6 is set to the solid line position as shown in FIG. 5 and heating operation is performed in the heating cycle indicated by the solid line arrow, the liquid refrigerant condensed in the indoor heat exchanger 1 is The liquid refrigerant flows from the liquid pipe 14 to the outdoor heat exchanger 7 through the flow divider 30, but first flows to the cooling pipe 20 of the sixth flock 26 at the lowest position, and After passing through the cooling pipe 20, the flow divider 3
A cooling pipe 20 that separates the water from the cooling pipe 20 through a branch pipe 31 and forms each pipe line of the upper first to fifth blocks 21 to 25.
The gas is collected by the header 40 and returned to the compressor 5 through the gas pipe 15.

Therefore, the liquid refrigerant flowing into the cooling pipe 20 of the sixth block 26 at the lowest level does not pass through the flow divider pipe 30 but flows directly from the liquid pipe 14, so as shown in FIG.
0, and the flow divider 30000 passes through the resistance flow divider pipe 310
From the saturation temperature equivalent to the evaporation pressure of the liquid refrigerant subjected to passage resistance,
The temperature increases by the pressure loss caused by each of the resistors, and the amount of frost formed in the sixth block 26 can be reduced.

Therefore, when the outdoor fan 8 is placed above the outdoor heat exchanger 7 as shown in FIG. Frost formation can be reduced.

On the other hand, as described above (during the heating operation, if the outdoor heat exchanger 7 frosts, the four-way switching valve 6 is switched as shown by the dotted line, the cooling cycle is started, the outdoor fan 8 is stopped, and the outdoor heat exchanger 7 is frosted). Defrosting is carried out by flowing a high-temperature gas refrigerant into the container 7. In this case, the gas refrigerant is
The liquid refrigerant flows from the header 40 through each branch pipe 32 to the cooling pipes 20 forming the pipes of the upper first to fifth blocks 21 to 25, and the liquid refrigerant condensed in each block 21 to 25 flows into each branch pipe. The total amount of liquid refrigerant that is collected in the flow divider 30 via the pipe 31 and then collected in the flow divider 30 is
It flows through the communication pipe 33 to the cooling pipe 20 of the sixth block 26 at the lowest position.

Therefore, during defrosting, the refrigerant always flows through the cooling pipe 20 of the sixth flock 26, so that the heat exchange is not deteriorated due to liquid accumulation, and as a result,
The lowest cooling pipe 2, which was difficult to defrost until now
Defrosting at 0 can also be performed efficiently, and together with the ability to reduce the amount of frost on the sixth flock 26 at the lowest position, the defrosting time can be shortened.

The embodiment described above is applied to the outdoor heat exchanger 7 of a heat pump type air conditioner, but it can also be similarly applied to an evaporator that exchanges heat with indoor air in a low-temperature refrigerator.

As described above (according to the present invention, the lower cooling pipe, which is difficult to defrost, is separated from the upper cooling pipe and connected to the merging side of the flow divider, and during defrosting, the liquid refrigerant condensed in the upper cooling pipe is collected. Since the refrigerant is allowed to flow through the lower cooling pipes, there is no possibility of liquid pooling and the refrigerant always flows, making it possible to defrost in a short time.

Moreover, when performing the evaporation action, the liquid refrigerant is depressurized by the expansion mechanism and then passes through the lower cooling pipe to the flow divider,
Since the flow is divided from the flow divider to the upper cooling pipe, the liquid refrigerant passing through the lower cooling pipe absorbs heat from the outside air and evaporates, but the evaporation temperature is equal to the pressure difference that occurs in the flow divider and flow pipe. The evaporation temperature of the liquid refrigerant passing through the upper cooling pipe can be raised higher than that of the liquid refrigerant, which makes it difficult to form frost. Therefore, the defrosting time can be shortened accordingly.

[Brief explanation of drawings]

Fig. 1 is a front view showing one embodiment of the heat exchanger of the present invention;
The figure is a plan view, Figure 3 is an explanatory diagram schematically showing the main parts,
Fig. 4 is a perspective view of only a part of the lowest block, Fig. 5 is a refrigerant piping system diagram of a heat pump type air conditioner to which the present invention is applied, and Fig. 6 is a Mollier diagram during defrosting. . 9... Expansion mechanism for heating, 14... Liquid pipe, 15...
Gas pipe, 20...Cooling pipe, 21-25...Upper block, 26...Lowest block, 30...Flow divider,
33...Communication pipe.

Claims (1)

[Claims] 1. For refrigerant evaporation, horizontal cooling pipes are arranged in multiple stages in the vertical direction, and the liquid refrigerant flowing through the cooling pipes is evaporated by exchanging heat with air, and during frosting, high-temperature gas refrigerant is flowed to perform defrosting. In the heat exchanger, the cooling pipes in the stage direction are divided into a plurality of blocks, one end of each upper block except the lowest block is used as a flow divider, and the other end is used as a gas pipe. In addition, one end side of the lowest block is connected to the confluence side of the flow divider via a communication pipe having no expansion mechanism, and the other end side is connected to the expansion mechanism via a liquid pipe. A heat exchanger for refrigerant evaporation.