JP3446260B2 - Refrigerant condenser - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant condenser having a structure in which a pair of headers are connected by a plurality of tubes, and the refrigerant flows in a meandering manner between the headers through the tubes.

[0002]

2. Description of the Related Art Conventionally, as this type of refrigerant condenser,
For example, a multi-flow (MF) type refrigerant condenser (condenser) as shown in FIG. 8 is provided. That is, the pair of headers 1 and 2 are connected by the plurality of tubes 3 each of which is a flat tube. A separator 4 is arranged at a predetermined position in each of the headers 1 and 2 so that the refrigerant flows in a meandering manner between the headers 1 and 2 through the tube 3.

In this case, in order to increase the heat exchange rate, in the method disclosed in Japanese Patent Laid-Open No. 63-161393, the number of times the refrigerant changes its flow direction in the headers 1 and 2 (hereinafter referred to as the number of turns) is 1. The configuration to be set above is described,
Japanese Patent Application Laid-Open No. 63-34466 discloses a configuration in which the number of tubes serving as the refrigerant passages is reduced so that the passage cross-sectional area of the refrigerant passages decreases from the inlet to the outlet.

[0004]

By the way, in the refrigerant condenser constituted by folding the refrigerant passage as in the above-mentioned conventional configuration, the number of turns of the refrigerant passage is increased and the condensing distance is set large to increase the flow velocity of the refrigerant. While the heat exchange rate can be increased by increasing the pressure loss inside the tube, the refrigerant pressure decreases, and the condensing temperature of the refrigerant decreases accordingly. For this reason, when the number of turns of the refrigerant passage is set excessively large, the temperature difference between the outside air temperature and the refrigerant becomes small, which causes a decrease in heat exchange performance.

On the other hand, by reducing the number of turns of the refrigerant passage and setting the condensing distance to be small, the pressure loss in the pipe can be reduced, but the flow velocity of the refrigerant is reduced and the heat transfer coefficient inside the pipe is small. There is a circumstance that the performance deteriorates. From the above, there should be an optimum number of turns of the refrigerant passage for each heat exchanger. However, in the above-mentioned conventional configuration, it is merely suggested that simply increasing the number of turns or decreasing the passage cross-sectional area contributes to the improvement of the heat exchange rate, and it is the most suitable for the heat exchanger. The condensing distance has not been specified, and the original problem of improving the heat exchange rate has not been solved.

The present invention has been made in view of the above circumstances. An object of the present invention is to condense a refrigerant having a structure in which a refrigerant passage is folded, and to design a high heat exchange rate by specifying the condensation distance. To provide a container.

[0007]

In order to achieve the above object, the present invention provides a plurality of laminated tubes, a pair of headers joined to both ends of the tubes, and arranged in the headers. A separator for dividing the tube into a plurality of tube groups, the high temperature and high pressure gaseous refrigerant flowing through the tube group changes its flow direction in the header, and the refrigerant changes its flow direction in the header. When the number of changes is N (integer) and the distance between the pair of headers is W (unit m), the condensation distance L (unit m) of the refrigerant is represented by L = (N + 1) W. When the distance L (unit: m) is a pipe equivalent diameter corresponding to the pipe area of the tube, de (unit: mm), de <
Under 1.15, the technical means of L = 0.4 + 1.18de to 0.7 + 1.18de is adopted.

[0008]

The condensation distance L is L = 0.4 + 1.18de.about.0.
7 + 1.18de (de is the diameter equivalent to the inside of the tube)
When set so that the heat exchange rate will be optimal for the refrigerant condenser, therefore, by setting the number of turns of the refrigerant passage so as to satisfy the above equation, the heat exchange rate is optimized. Can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a refrigerant condenser of an automobile air conditioner will be described below with reference to FIGS. FIG. 2 shows an MF type refrigerant condenser. In FIG. 2, a core 13 is connected between the pair of headers 11 and 12. The core 13 includes corrugated fins 13 between a plurality of flat tubes 13a.
It is formed by welding b. Further, a separator 14 is arranged at a predetermined position inside the headers 11 and 12, and the number of turns of the refrigerant passage can be arbitrarily set depending on the arrangement position of the separator 14 as shown in FIG. That is, when the number of the tubes 13a is 32, all the 32 tubes 13a are unidirectional refrigerant passages in the 0 turn, and in this case, the condensation distance L is W. Here, W is the header 11,
It is the distance between the cores 12 and matches the width of the core 13. Further, in one turn, the tubes 13a can be set in a combination of 16 tubes, 16 tubes, or a combination of 24 tubes, 8 tubes, etc. In this case, the condensation distance L becomes 2W.
In 2 turns, 11 tubes 13a, 11
It is possible to set a combination of ten, ten, or a combination of six, twelve, four, etc. In this case, the condensation distance L is 3 W. The one shown in FIG. 3 is an example of a combination of the tubes 13a, and other combinations can be set arbitrarily.

FIGS. 4 and 5 show the tendency with respect to the number of turns of the refrigerant passage when the core size is set to various dimensions when the tube inner side equivalent diameter de = 0.67 mm. That is, in FIG. 4, the number of tubes 13a is two.
4, core height H is 235.8 mm, core thickness D is 16 mm
In the heat exchanger (see Fig. 2), the core width W is 300 mm.
The performance ratio is shown for 0 turns when the number of turns of the refrigerant passage is set from 1 to 5 and every 100 mm from 100 to 700 mm. FIG. 5 shows a heat exchanger having 40 tubes 13a, a core height H of 387.8 mm, and a core thickness D of 16 mm, and a core width W of 30.
The performance ratio with respect to 0 turns when the number of turns of the refrigerant passage is set from 1 to 6 is shown for every 100 mm from 0 mm to 700 mm. The equivalent diameter de refers to the diameter corresponding to the cross-sectional area of the tube 13a because the passage shape of the tube 13a usually has a cross section as shown in FIGS. 6 (a) and 6 (b). That is, de (equivalent diameter)
= 4 × (cross-sectional area) / (wet edge length)

Here, it is conceivable to combine various numbers of tubes 13a with a plurality of turns, as shown in FIG.
FIG. 5 shows the result of calculation for the one with the highest performance. In other words, the performance of the condenser is determined by the balance between the improvement of the heat transfer coefficient and the pressure loss, and since the two influence each other, it can be derived by formulating the relationship between the two and various heat exchanges. It is possible to obtain the efficiency of the container. As this calculation, detailed heat transfer coefficient characteristics and pressure loss characteristics were obtained by an experiment, and a simulation program was created based on the results and analyzed. As the setting conditions of each parameter at this time, it is assumed that the load is the largest in the refrigeration cycle of the automobile air conditioner, and the air temperature at the condenser inlet is 35 ° C, the condenser inlet pressure is 1.74 MPa, and the condenser inlet pressure is 1.74 MPa. Superheat 20 ° C, subcool 0 ° C at condenser outlet, wind velocity 2m / s at condenser inlet, HFC-134a was used as the refrigerant. As a result of comparing this analysis and the experimental result, the present inventor confirmed that the analytical result and the experimental value are substantially the same when the tube inner side equivalent diameter of the tube 13a is about 0.6 mm to 1.15 mm. In addition, the number of turns (optimum number of turns) having the highest performance shown in FIG. 4 and FIG. 5, even if the fin pitch is different,
Alternatively, it was confirmed that the same result was obtained even if the core thickness D was different.

From the above-mentioned FIGS. 4 and 5, it was found that even if the number of tubes 13a is different, if the core width W is the same, the optimum number of turns is the same. This means that if the core width W is the same, the optimum number of turns is the same regardless of the combination of the numbers of the tubes 13a. In FIG. 7, the above-described calculation is performed for the tubes 13a having different equivalent diameters de inside the tube, and each core width W
This is the result of finding the optimum number of turns for each. In this case, the number of turns actually exists only as an integer, but in order to show a tendency, it is also expressed in a region other than an integer.

Now, in FIG. 7, for example de = 0.6
Focusing on the 7 mm tube 13a, the condensation distance L at the optimum turn is 3 turns when W = 300 mm, so L = (3 (turns) +1) × 300 = 1200 mm,
When W = 400 mm, there are two turns, so L = (2+
1) x 400 = 1200 mm, W = 500 mm, 2 turns, so L = (2 + 1) x 500 = 1500 m
When m and W = 600mm, one turn, so L =
When (1 + 1) × 600 = 1200 mm and W = 700 mm, there is one turn, so L = (1 + 1) × 700 = 14
It will be 00 mm. When the equivalent diameter de of the tube 13a is 0.9 mm, the condensation distance L is 1500 mm when W = 300 mm, 1600 mm when W is 400 mm, W
Is 500 mm when W is 500 mm, 1800 mm when W is 600 mm, and 1400 mm when W is 700 mm.
When the equivalent diameter de of the tube 13a is 1.15 mm, the condensation distance L is 1800 when W = 300 mm.
mm, 2000 mm when W is 400 mm, 2000 mm when W is 500 mm, 1800 mm when W is 600 mm,
When W is 700 mm, it becomes 2100 mm. Usually, the core width of the refrigerant condenser of the vehicle air conditioner is W = 30
Since it is used in the range of 0 mm to 800 mm, from the above calculation results, when the equivalent diameter de of the tube 13a has the same dimension, the core width W is not so much affected and the optimum condensation distance L is constant. It was found to exist within the range of.

Therefore, the equivalent diameter d of the tube 13a
The optimal condensation distance L can be specified for e. FIG. 1 shows the results obtained by changing the equivalent diameter de and determining the existence range of the optimum condensation distance L for the de by the above analysis. When the obtained data is linearly approximated, the optimum condensation distance L is

[0015]

## EQU1 ## It can be set as L = 0.4 + 1.18de to 0.7 + 1.18de. (However, the unit of L is m,
Therefore, if the equivalent diameter de of the tube 13a of the core 13 of the heat exchanger is known, the optimum condensation distance L can be obtained from equation 1, and the number of turns should be adjusted to match this condensation distance. The optimum number of turns (N) can be set by obtaining the following formula.

[0016]

## EQU00002 ## N (number of turns) = L / W-1 Since the number of turns according to the equation 2 needs to be an integer,
It is necessary to round off the obtained number of turns. Recent advances in refrigerant condenser tube manufacturing techniques have made it possible to manufacture tubes with extremely small diameters. When the above formula 1 is applied to such an extremely thin tube, the number of turns is set to 0. For example, FIG. 9 shows a trace obtained by using the above-mentioned simulation program to find the optimum condensation distance at a high idle load and a constant load of 40 km / h for the equivalent diameter de of 0.60 mm or less. The equivalent diameter is 0.18 mm to 0.5 mm when viewed from the line during high idle load.
Since the optimum condensation distance L is 300 mm to 800 mm, the core width W is 300 mm to 80 mm as described above.
At 0 mm, the optimum number of turns is 0.

[0017]

As described above, according to the structure of the present invention, the optimum condensation distance L is determined from the equivalent diameter de of the tube 13a of the core 13 of the heat exchanger, and the condensation distance L is determined.
Since the optimum number of turns of the refrigerant passage is calculated from
A heat exchanger with a high heat exchange rate can be designed, unlike the conventional example which merely suggested that an increase in the number of turns and a decrease in the passage cross-sectional area contribute to the improvement of the heat exchange rate.

[0019]

As is apparent from the above description, according to the heat exchanger of the present invention, the pair of headers are connected by a plurality of tubes, and the refrigerant is meandered between the headers through the tubes. In a heat exchanger configured to flow, the condensation distance that increases the heat exchange rate is obtained from an arithmetic expression, and the number of turns of the refrigerant passage is set based on the arithmetic expression. In the case of the returning structure, the excellent effect that the heat exchange rate can be designed high can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an equivalent diameter of a tube and a condensation distance in an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the configuration of a heat exchanger.

FIG. 3 is a diagram showing the relationship between the number of turns of the refrigerant passage, the combination of tubes, and the condensation distance.

FIG. 4 is a characteristic diagram showing the relationship between the number of turns of the refrigerant passage and the performance ratio with respect to 0 turns.

FIG. 5 is a characteristic diagram showing the relationship between the number of turns of the refrigerant passage and the performance ratio with respect to 0 turns.

FIG. 6 is a cross-sectional view showing a core tube.

FIG. 7 is a characteristic diagram showing the relationship between the core width and the optimum number of turns.

FIG. 8 is a schematic diagram showing a configuration of a heat exchanger in a conventional example.

FIG. 9 is a diagram showing a relationship between a tube equivalent diameter and a condensation distance in a tube having a small equivalent diameter.

[Explanation of symbols]

11,12 header 13 cores 13a tube 14 Separator

Continuation of the front page (56) Reference JP-A-2-85659 (JP, A) JP-A-63-161393 (JP, A) JP-A-63-34466 (JP, A) JP-A-62-175588 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F25B 39/04 F25B 39/00

Claims (2)

(57) [Claims] 1. A stack of a plurality of tubes, a pair of headers joined to both ends of the tubes, a separator disposed in the header and dividing the tubes into a plurality of tube groups, HFC-a high-temperature and high-pressure gas inside the tube group
134a refrigerant flows, this high-temperature high-pressure gaseous refrigerant changes its flow direction in the header, and the number of times the refrigerant changes its flow direction in the header is N (integer), and between the pair of headers. When the distance is W (unit m), the condensation distance L (unit m) of the refrigerant is represented by L = (N + 1) W, and the condensation distance L (unit m) is the conduit area of the tube. In the range of 0.60 <de <1.15 , L = 0.4 + 1.18de to 0.7 + 1.18de when the equivalent diameter in the tube corresponding to is de (unit: mm). Refrigerant condenser for automotive air conditioners. 2. A plurality of stacked tubes, a pair of headers joined to both ends of the tubes, and a plurality of tubes arranged inside the headers.
And a separator for dividing the blanking group, HFC-1 of the tube group has high temperature and high pressure gaseous
34a refrigerant flows, and this high-temperature and high-pressure gaseous refrigerant is
Redirecting its flow in a header, said refrigerant redirecting its flow in said header
Let N be an integer and the distance between the pair of headers
When W (unit: m), the refrigerant condensation distance L (unit:
m) is represented by L = (N + 1) W, and this condensation distance L (unit: m) is the conduit area of the tube.
If the equivalent diameter in the tube corresponding to is de (unit: mm)
In the range of 0.1 <de <0.6, L = 0.187 + 1.56de to 0.05 + 2.5d
e (however, L <= 1) , The refrigerant condenser characterized by the above-mentioned.