JPH05203285A - Heat exchanger - Google Patents

Abstract

PURPOSE:To provide a heat exchanger which is equipped with a flow divider which divides the flow of refrigerant in a two phase state (vapor and liquid) in a plurality of refrigerant circuits and capable of heat exchanging with a high efficiency by dividing the refrigerant between the refrigerant circuits equally in terms of a refrigeration cycle of refrigerator or air conditioner. CONSTITUTION:This heat exchanger comprises a cylinder-shaped flow divider 12, a cylinder-shaped flow combiner 13, heat exchanger tubes 14 welded to the flow divider 12 and the low combiner 13 and a large number of fins 15 installed to the heat exchanger tubes. The diameter of the flow divider 12 is designed to exceed the diameter of the flow combiner 13. Therefore, this heat exchanger comprises the flow divider and the flow combiner which are cylinder-shaped and sealed on both ends and the fins installed in great numbers. Since the diameter of the flow divider is larger than that of the flow combiner, refrigerant can be flow-divided between heat exchanger tubes from the flow divider equally so that efficient heat exchange may be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger having a flow divider used as a header pipe in an evaporator such as a refrigerating machine or an air conditioner.

[0002]

2. Description of the Related Art In recent years, in response to a demand for miniaturization and high efficiency of heat exchangers, header pipes and the like have been used in order to cope with a reduction in diameter of round heat transfer tubes and a large number of circuits associated with flat heat transfer tubes. Is used as a shunt (for example, Shoukaisho 63-17368).
No. 9).

An example of the conventional heat exchanger described above will be described below with reference to the drawings. FIG. 7 shows a perspective view of a conventional heat exchanger. In FIG. 7, 1 is a heat exchanger,
A plurality of heat transfer tubes 4 are joined in two rows to the flow distributors 2 and 3 of which the both ends are sealed and have the same diameter, and a large number of fins 5 are arranged in the heat transfer tubes 4. The flow divider 2 has an inlet pipe 6 and an outlet pipe 7.
Is attached, and the flow dividers 2 and 3 are provided with partitions 2a, 2b and 3
a is provided, and the heat transfer tube 4 constitutes a circuit of the refrigerant R.

The operation of the heat exchanger configured as described above when used as an evaporator will be described below with reference to the drawings.

In FIG. 7, the refrigerant R in the gas-liquid two-phase state flowing from the inlet pipe 6 into the compartment 2A of the flow divider 2 is divided into the partition 2a.
The heat is divided into a plurality of lower heat transfer tubes 4 and discharged. The refrigerant R is provided with a large number of fins 5 arranged in the heat transfer tube 4.
Through heat exchange with the air A flowing in from the front surface of the heat exchanger 1, and flows into the compartment 3A of the flow divider 3 while evaporating. The refrigerant R merged in the flow divider 3 flows upward in the flow divider 3 and is distributed to the plurality of heat transfer tubes 4 below the partition 3a and flows out. Similarly, the refrigerant R, which is evaporated while repeating merging and distribution in the flow dividers 2 and 3, becomes dry vapor and merges in the section 2C above the partition 2b flows out from the outlet pipe 7 attached to the flow divider 2. ..

8 and 9 are cross-sectional views of the flow dividers 2 and 3, showing how the refrigerant R flows. The arrows in the drawings show the refrigerant R.
Shows the direction of flow of. The refrigerant R in the two-phase state of gas-liquid 2 that has flowed in from the inlet pipe 6 evaporates in the heat exchanger 1, while the degree of dryness is gradually increased and the diversion is repeated to become dry vapor.
It flows out from the outlet pipe 7.

[0007]

However, in the above-mentioned configuration, as shown in FIGS.
As the dryness increases in the inner sections 2A to 2C and 3A to 3B, the flow mode changes from the froth flow to the annular spray flow. In the vertical upward gas-liquid two-phase flow, a floss flow occurs when the dryness is small, and an annular spray flow occurs when the dryness increases. For example, the vertical upward flow flow pattern diagram shown in Fig. 10 (Mechanical Engineering Handbook)
Basic A5 Fluid Engineering Published by The Japan Society of Mechanical Engineers (1986)
According to A5-Page 153), Freon R22 (pressure 0.7 MPa), which is generally used for refrigerant R, is used for air conditioning.
When the dryness is 0.2, the flow pattern of the refrigerant R becomes a point on the line L1 and when the dryness is 0.6, the flow pattern of the refrigerant R becomes a point on the line L2. Here, the dryness of 0.2 is the state of the refrigerant R at the inlet of the evaporator heat exchanger of a general refrigeration cycle, and the dryness of 0.6 is the state of the intermediate refrigerant until reaching the outlet.

Points P1 and P2 are points when the refrigerant R of each dryness has the same mass flow rate, and even when the refrigerant R has the same mass flow rate, the larger the dryness is, the more likely it is that an annular atomization flow occurs. .. The points P1 and P2 move downward on the lines L1 and L2 as the flow rate of the refrigerant R decreases due to the decrease in the mass flow rate of the refrigerant R, and the apparent flow rates of the gas phase and liquid phase of the refrigerant R decrease. .. Thus, even when the refrigerant R has the same mass flow rate, the sections 3B, 2
In C, an annular spray flow is likely to occur after the refrigerant R merges.

Further, the sections 3B and 2C which have become the annular spray flow.
Then, the refrigerant R sequentially flows out to the heat transfer tube 4 while flowing upward, so that the mass flow rate of the refrigerant R in the flow dividers 2 and 3 decreases,
The apparent flow velocities of the refrigerant R in the gas phase and the liquid phase become slower, as shown in FIG.
At, it will move downwards and eventually move to the froth flow.

When the gas-liquid two-phase flow splits, the fact that the flow mode greatly affects the split flow ratio is, for example, a study on the gas-liquid two-phase flow behavior from the horizontal pipe to the vertical branch pipe (first Report) (1991-5) The 28th Japan Heat Transfer Symposium Proceedings Proceedings, pp. 766 to 768. As shown in Fig. 11, the split ratio of the refrigerant R is greatly different between the annular spray basin and the floss basin. It has been found that the liquid phase of the refrigerant R is more likely to flow out in the floss flow.

From the above, immediately after the refrigerant R has flowed into the heat exchanger 1, and since the degree of dryness is small, the liquid phase of the refrigerant R is different in each of the sections 2A and 3A in which the froth flow is likely to occur in all regions. The flow is evenly distributed to the heat transfer tube 4. However, the sections 2B and 3B into which the refrigerant R flows after being evaporated to some extent in the heat exchanger 1
Then, since the dryness is high, an annular spray flow is likely to occur at first. However, if the refrigerant R flows upward in the compartments 2B and 3B, the refrigerant R sequentially flows out to the heat transfer tube 4, so that the mass flow rate decreases and the refrigerant flows to the floss flow.

Therefore, the liquid phase of the refrigerant R is hard to flow out from the upper part where the lower part, which is the annular spray flow, becomes the floss flow, and almost the gas phase of the refrigerant R flows into the heat transfer tube 4 joined to this part. Therefore, most of the evaporation takes place, and the amount of heat exchange is very small. In addition, the refrigerant R in all the flow dividers 2 and 3
If the diameters of the cylindrical flow distributors 2 and 3 are made sufficiently large in order to make the floss flow, it is necessary to make the diameter very large especially for the flow distributors 2 and 3 near the outlet where the dryness is high. Yes, the volume of the heat exchanger 1 becomes very large due to the portions that do not directly perform heat exchange, that is, the flow distributors 2 and 3, which conflicts with the demand for miniaturization of the heat exchanger 1. It had one problem.

In the heat transfer tube 4 near the outlet of the refrigerant R, the refrigerant has completely evaporated in both the front and rear rows.
There is a second problem that the portion B near the outlet hardly contributes to heat exchange, and in the portion B near the outlet, the air A that is not cooled or dehumidified passes through the heat exchanger 1 and the heat exchange amount decreases. Was.

Therefore, the present invention has a flow divider that evenly distributes the refrigerant to each heat transfer tube when used as an evaporator,
It is an object of the present invention to provide a small-sized heat exchanger capable of efficiently exchanging heat.

[0015]

In order to solve the above-mentioned first problem, a heat exchanger according to the present invention has a tubular flow distributor whose both ends are sealed and a tubular flow distributor whose both ends are sealed. Of the confluencer, a plurality of heat transfer tubes joined to the confluencer and the confluencer at a substantially right angle, and a plurality of fins arranged on the heat transfer tube, the diameter of the confluencer being the confluencer. It has a structure larger than the diameter of.

Further, in order to solve the above-mentioned problems of the first problem and the second problem at the same time, the heat exchanger of the present invention has a tubular flow distributor whose both ends are sealed, and both ends are sealed. A tubular confluencer, a plurality of heat transfer tubes joined to the flow concentrator and the confluencer at substantially right angles, and a plurality of fins arranged on the heat transfer tube, and the diameter of the flow concentrator is It has a structure larger than the diameter of the merger, and the flow divider and the merger are installed in parallel.

Further, in order to solve the above-mentioned problems of the first problem and the second problem at the same time, the heat exchanger of the present invention has a cylindrical shape whose both ends are sealed in order to increase the diameter of the flow distributor. It is composed of a flow distributor, a tubular combiner whose both ends are sealed, the flow distributor, a plurality of heat transfer tubes joined to the combiner at substantially right angles, and a large number of fins arranged on the heat transfer tube. A structure in which the flow distributor and the confluencer are installed in parallel, and the heat transfer tube is eccentrically joined to the cross-section center line of at least one of the tubular flow concentrator or the tubular confluencer. Is to have.

[0018]

According to the present invention, due to the above-mentioned constitution, only the flow diversion by the flow diverter at the inlet portion having the smallest dryness can be achieved. Moreover, in the parallel flow divider and merge device, the diameter of the tubular flow divider is made larger than that of the tubular flow divider, and the diameter of the flow divider is made smaller, thereby increasing the volume of the entire heat exchanger. Without, the flow velocity of the refrigerant in the flow divider becomes slower, and since the refrigerant is before being evaporated in the heat exchanger, the dryness is small,
The gas-liquid two-phase refrigerant becomes a froth flow in almost the entire region of the flow divider. Therefore, the liquid-phase refrigerant flows out almost uniformly to all the heat transfer tubes connected to the flow divider, and the evaporation is similarly performed in all the heat transfer tubes, so that the heat exchange is efficiently performed.

Further, by installing the flow divider and the confluent device in parallel, the fluid passing through the heat exchanger, such as air, will flow in at least two rows on one side of the heat transfer tube and the refrigerant and the heat at the initial stage of evaporation. Since all the fluids are exchanged and are cooled or dehumidified and pass through the heat exchanger, heat exchange is efficiently performed.

By eccentrically joining at least one of the flow divider or the flow confluencer to the heat transfer tube, the diameter of the flow divider can be increased without coming into contact with the flow merger. Therefore, it is possible to reduce the flow velocity of the refrigerant in the flow divider with a small dryness, and since the refrigerant is before evaporating in the heat exchanger, the dryness is small and almost in the entire area of the flow divider.
The gas-liquid two-phase refrigerant becomes a froth flow. Therefore, the liquid refrigerant flows out almost uniformly to all the heat transfer tubes connected to the flow divider, and the evaporation is similarly performed in all the heat transfer tubes. Further, by installing the flow divider and the merger in parallel, the fluid passing through the heat exchanger, such as air, can exchange heat with the refrigerant in the initial stage of evaporation in one row of the heat transfer tubes having at least two rows. Since all the fluid is cooled or dehumidified and passes through the heat exchanger, heat exchange is efficiently performed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a heat exchanger according to an embodiment of the present invention. Reference numeral 11 denotes a heat exchanger, and a plurality of heat transfer tubes 14 are joined in a row to a tubular flow divider 12 whose both ends are sealed. In addition, a plurality of heat transfer tubes 14 are provided in the confluence unit 13 arranged in parallel.
Are joined in one row, the heat transfer tubes 14 are installed in two rows, and a large number of fins 15 are arranged. The heat transfer tube 14 joined to the flow distributor 12 is appropriately connected in a U-shape to form a circuit of the refrigerant R1. An inlet pipe 16 is joined to the flow distributor 12 and an outlet pipe 17 is joined to the combiner 13.

FIG. 2 is a plan view of an essential part of the heat exchanger 11.
Here, when the circular center points of the flow divider 12 and the flow combiner 13 are arranged in parallel, the diameter 12r of the flow divider 12 and the diameter 1 of the flow combiner 13 are equal to each other.
3r is RP × 2 ≧ 1 with respect to the row pitch RP of the heat transfer tubes 14.
It must be 2r + 13r, but by making the diameter 12r of the flow distributor 12 larger than the diameter 13r of the flow combiner 13, it is possible to increase the size of the flow distributor 12 to an appropriate diameter.

The operation of the heat exchanger 11 configured as described above will be described below with reference to FIGS. 1 and 3.

The gas-liquid two-phase refrigerant R1 having a low degree of dryness flows into the flow divider 12 through the inlet pipe 16. While flowing upward in the flow distributor 12, it sequentially flows out to the heat transfer tube 14. Fins 1 arranged in a heat transfer tube 14 that is appropriately connected in a U shape
After evaporating while exchanging heat with the air A1 flowing from the front surface on the side of the flow divider 12 via 5, and becoming dry steam in the heat transfer tube 14 on the rear surface side of the heat exchanger 11, the flow reaches the merger 13 and merges.
It flows out from the outlet pipe 17.

FIG. 2 is a cross-sectional view showing the state of the refrigerant R1 inside the flow divider 12, in which the refrigerant R1 has a small dryness and a diameter 12r is appropriately increased so that the flow velocity is sufficiently small. It becomes the floss style. Thereafter, the refrigerant R1 flows upward into the heat transfer tube 14 as the mass flow rate gradually decreases and the flow velocity decreases as it flows out to the heat transfer tube 14, but the flow mode remains the froth flow.

Therefore, the refrigerant R1 uniformly flows out to each heat transfer tube 14 and evaporates equally in each heat transfer tube 14. The refrigerant R1 split in the flow distributor 12 evaporates in the U-shaped heat transfer tubes 14 without joining again and reaches the flow combiner 13. The ratio of the liquid phase mass flow rate of the refrigerant R1 flowing out from the flow divider 12 at this time is shown by the length of the arrow in FIG.

Further, by installing the flow divider 12 and the flow combiner 13 in parallel, all the air A1 passing through the heat exchanger 11 can be obtained.
In the row of the heat transfer tubes 14 on the upstream side, heat is exchanged with the refrigerant R1 in the initial stage of evaporation, and all the air A1 is cooled and passes through the heat exchanger 11, so that the efficiency is good.

As described above, since all the air A1 is equally cooled and dehumidified on the entire surface of the heat exchanger 11, the heat exchange efficiency is good.

As described above, according to this embodiment, the shunt 1
2, a confluence unit 13, and a large number of fins 15 are provided in a heat transfer tube 14, and the diameter 12r of the flow divider 12 is connected to the confluence unit 1.
By making it thicker than 13r of 3, it is possible to increase the diameter of the flow divider 12 to an appropriate diameter, keep the refrigerant R1 of the gas-liquid two-phase flow in the flow divider 12 as a floss flow, and join the flow divider 12. The heat is uniformly distributed to the heat transfer tube 14, and the flow distributor 12 and the combiner 13 are installed in parallel, so that heat can be efficiently exchanged over the entire surface of the heat exchanger 11.

Another embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows the entire heat exchanger according to another embodiment of the present invention, in which 21 is a heat exchanger, and a plurality of heat transfer tubes 24 are provided in a tubular flow distributor 22 whose both ends are sealed. Joined in rows. Further, a plurality of heat transfer tubes 24 provided with a large number of fins 25 are also joined to the confluence unit 23 arranged in parallel, and the heat transfer tubes 24 are installed in two rows and a large number of fins 25 are provided. The heat transfer tube 24 joined to the flow divider 22 is appropriately U
They are connected in a letter shape and form a circuit of the refrigerant R2. An inlet pipe 26 is joined to the flow distributor 22 and an outlet pipe 27 is joined to the combiner 23.

FIG. 5 is a plan view of an essential part of the heat exchanger 21.
Here, the heat transfer tube 2 is attached to the center line of the cross section of the tubular flow divider 22.
4 are eccentrically joined, and the diameter of the flow divider 22 can be appropriately increased.

The operation of the heat exchanger 21 configured as described above will be described below with reference to FIGS. 4 and 6.

When used as an evaporator, a refrigerant R2 in a gas-liquid two-phase state having a low degree of dryness is introduced from the inlet pipe 26 into the flow divider 2.
Inflow to 2. While flowing upward in the flow divider 22, it sequentially flows out to the heat transfer tube 24. It evaporates while exchanging heat with the air A2 flowing from the front surface on the side of the flow divider 22 through the fins 25 arranged in the heat transfer pipes 24 that are appropriately connected in a U shape,
After becoming dry steam, it reaches the combiner 23, merges, and flows out from the outlet pipe 27.

FIG. 6 is a sectional view showing the state of the refrigerant R2 inside the flow divider 22. At this time, since the refrigerant R2 has a low degree of dryness and a sufficiently low flow velocity, it becomes a froth flow from the beginning. Thereafter, the refrigerant R2 flows upward while the mass flow rate gradually decreases and the flow velocity decreases because the refrigerant R2 flows out to the heat transfer tube 24, but the flow mode remains the froth flow. Therefore, the refrigerant R
The reference numeral 2 equally flows out to each heat transfer tube 24 and evaporates equally in each heat transfer tube 24. The liquid phase mass flow rate of the refrigerant R2 flowing out of the flow divider 22 at this time is shown by the length of the arrow in FIG.

Further, by installing the flow divider 22 and the merger 23 in parallel, the air A2 passing through the heat exchanger 21 exchanges heat with the refrigerant R2 in the initial stage of evaporation in the row of the heat transfer tubes 24 on the upstream side. This means that all the air A2 is cooled and passes through the heat exchanger 21, so that the efficiency is good.

As described above, since all the air A2 is equally cooled and dehumidified on the entire surface of the heat exchanger 21, the heat exchange efficiency is good.

As described above, according to this embodiment, the shunt 2
2 and the confluence | merging machine 23 and the many fins 25 are comprised by the heat-transfer tube 24 arrange | positioned. Eccentrically joined to each other, the diameter of the flow diverter 22 can be made sufficiently large, and the gas-liquid two-phase flow of the refrigerant R2 is maintained as a froth flow in the entire flow diverter 22. The heat is evenly distributed to the joined heat transfer tubes 24, and heat can be efficiently exchanged over the entire surface of the heat exchanger 21.

In this embodiment, the diameter of the flow divider 22 is larger than that of the confluencer 23. However, the diameter may be the same, and it is needless to say that the same effect can be obtained even if the confluencer 23 is eccentric.

[0040]

As described above, the following effects can be obtained with the heat exchanger of the present invention.

The heat exchanger of the present invention has a tubular flow distributor whose both ends are sealed, a tubular flow combiner whose both ends are closed, and the flow distributor and the flow combiner are joined at substantially right angles. It is composed of multiple heat transfer tubes and a large number of fins arranged in the heat transfer tubes, and the diameter of the flow distributor is larger than the diameter of the confluencer, so that the refrigerant is evenly distributed from the flow distributor to each heat transfer tube, and the efficiency is improved. Heat exchange takes place.

Further, a cylindrical flow divider whose both ends are sealed,
It consists of a tubular confluencer with both ends sealed, a plurality of heat transfer tubes joined to the flow concentrator and the confluencer at substantially right angles, and a number of fins arranged on the heat transfer tube. Is larger than the diameter of the confluencer, the shunt and the confluencer are installed in parallel,
Since the heat transfer tube is composed of at least two rows,
The refrigerant is evenly distributed from the flow distributor to the heat transfer tubes, and heat is efficiently exchanged on the entire surface of the heat exchanger.

Further, a cylindrical flow divider whose both ends are sealed,
It is composed of a tubular confluencer with both ends sealed, a plurality of heat transfer tubes in at least two rows joined to the flow distributor and the confluencer at substantially right angles, and a large number of fins arranged in the heat transfer tube. A configuration in which the flow distributor and the merger are installed in parallel, and the heat transfer tubes are eccentrically joined in line with respect to the sectional centerline of at least one of the cylindrical flow distributor and the cylindrical merger. As a result, the refrigerant is evenly distributed from the flow distributor to the heat transfer tubes, and heat is efficiently exchanged on the entire surface of the heat exchanger.

[Brief description of drawings]

FIG. 1 is a perspective view of a heat exchanger according to an embodiment of the present invention.

FIG. 2 is a plan view of an essential part of the heat exchanger of FIG.

FIG. 3 is a cross-sectional view of a main part of the heat exchanger of FIG.

FIG. 4 is a perspective view of a heat exchanger according to another embodiment of the present invention.

5 is a plan view of a main part of the heat exchanger of FIG.

6 is a cross-sectional view of a main part of the heat exchanger of FIG.

FIG. 7 is a perspective view of a conventional heat exchanger.

8 is a cross-sectional view of the main parts of the heat exchanger of FIG.

9 is a cross-sectional view of a main part of the heat exchanger of FIG.

Fig. 10 Flow pattern diagram of vertical upward flow

FIG. 11 is a characteristic diagram showing the relationship between the flow mode and the diversion ratio.

[Explanation of symbols]

 11, 21 Heat exchanger 12, 22 Flow divider 13, 23 Combiner 14, 24 Heat transfer pipe 15, 25 Fin

Claims (3)

[Claims] 1. A tubular flow distributor with both ends sealed, a tubular combiner with both ends sealed, and a plurality of heat transfer tubes joined to the flow distributor and the combiner at substantially right angles. And a plurality of fins arranged in the heat transfer tube, wherein the diameter of the flow distributor is larger than the diameter of the confluencer. 2. The heat transfer tube is composed of at least two rows or more, and a tubular flow distributor whose both ends are sealed and a tubular flow combiner whose both ends are sealed are installed in parallel. The heat exchanger described in. 3. A tubular flow distributor whose both ends are sealed, a tubular combiner whose both ends are sealed, and a plurality of at least two rows which are joined to said flow distributor and said combiner at substantially right angles. Of the heat transfer tube and a large number of fins arranged on the heat transfer tube, the flow distributor and the flow combiner are installed in parallel, and at least the tubular flow divider or the tubular flow combiner. A heat exchanger characterized in that the heat transfer tube is eccentrically joined to one of the center lines of the cross section.