JP2001041671A - Heat exchanger for air conditioning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain conditions for optimizing a heat transfer of a heat exchanger for air conditioning having a specific dimension of a diameter of a tube by specifying an outer diameter, first pitch and second pitch of the tube. SOLUTION: A tube 1 having an outer diameter of 6 mm is first used, and is finished to the tube 1 having an outer diameter of a finished dimension of 6.3 mm. Then, plate fins 2 are alternately disposed. Various types of the fins 2 having a first pitch L1 in each row of a longitudinal direction of the fins 2 are prepared, and air side heat transfer performances at the pitch L1 of the fins 2 are measured. Then, the first pitch indicating a maximum value of the transfer performance at that time is fixed to the L1. Then, a second pitch L2 in a width direction of the fins 2 is variably changed this time, and the respective heat transfer performances of the fins 2 are obtained by an experiment. As a result, the performance is the maximum at the first pitch L1 between 2.50D to 3.20D, and becomes good at the second pitch L2 between 1.85D to 4.25D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate fin type air conditioner heat exchanger, in which louvers and slit fins are mainly disposed in an indoor unit, and corrugated (corrugated) fins are disposed in an outdoor unit. .

[0002]

2. Description of the Related Art A plate fin of a heat exchanger for air conditioning has an elongated flat rectangular shape, and a large number of tube insertion holes are arranged at positions matching each other in a staggered manner so as to be spaced apart from each other in the width direction and the longitudinal direction. A louver or a slit is formed between the holes, or bent into a mountain shape. And many plate fins are arranged parallel to each other with a small gap,
Tubes having a circular cross section are inserted through the respective tube insertion holes. The gas-liquid two-phase refrigerant is circulated in the tube, and the fan circulates air on the outer surface of the tube and on the fin side in the width direction of the fin. Such a conventional plate-fin type air conditioning heat exchanger generally has a tube diameter of about 10 mm.

[0003]

The outer diameter of the tube is made smaller, a plurality of rows of refrigerant flow paths are arranged in parallel, and the refrigerant flows through each tube row through distribution pipes to improve heat transfer efficiency. At the same time, it is required to reduce the length of the fins in the width direction to make the indoor air-conditioning heat exchanger compact. Since the outer diameter of the tube of the conventional air-conditioning heat exchanger was relatively large, the optimal design conditions for the narrow plate fin having a small tube diameter were unknown. Therefore, an object of the present invention is to experimentally determine the optimum conditions of a heat exchanger for air conditioning having a tube diameter of about 6 mm, which is extremely small as compared with the conventional one.

[0004]

According to the first aspect of the present invention, a plurality of tube insertion holes are arranged at regular intervals of a first pitch L1 at positions aligned with each other and spaced apart in the longitudinal direction. A plurality of elongated plate fins arranged in a staggered plurality of rows at regular intervals of a second pitch L2 spaced apart in the width direction and shifted by a half pitch in the longitudinal direction with respect to an adjacent row; Fins are arranged in parallel with each other with a small gap, a tube having a circular cross section is inserted into the tube insertion hole, and an air flow flows in the width direction of the plate fin, and a critical temperature is set in the tube.
In an air conditioner heat exchanger through which a refrigerant of 90 ° C or lower flows,
The outer diameter D of the tube is 5 mm to 7 mm, the first pitch L1 is 2.50 D to 3.20 D, and the second pitch L
2 is an air conditioner heat exchanger characterized by having a diameter of 1.85D to 4.25D.

According to a second aspect of the present invention, in the first aspect, two or three rows of tube insertion holes are formed in the width direction of the plate fin, and a refrigerant is arranged in parallel for each tube row. Refrigerant piping is connected to the inlet side of each tube row via a branch portion so as to circulate, and a large number of louvers or slit cut-and-raised portions are formed on the surface of the plate fin in parallel with the longitudinal direction, or have a width. The fins are bent in a wave shape in which the wave travels in the direction, the distance d between adjacent plate fins is in the range of 1.0 mm to 1.5 mm, and the cut-and-raised height of the louver or slit is in the range of 0.4 mm to 0.9 mm. There is a heat exchanger for air conditioning.

According to a third aspect of the present invention, in the second aspect, the cut-and-raised pitch of the slit is 1.0 mm to 2.5 mm.
mm is the heat exchanger for air conditioning. A fourth aspect of the present invention is the air conditioner heat exchanger according to the second aspect, wherein the cut-and-raised pitch of the louver is 2.0 mm to 5.0 mm. According to a fifth aspect of the present invention, in the second aspect, the wave of the waveform is generated for every unit tube row in the width direction of the plate fin.
This is an air-conditioning heat exchanger formed with four to four bends.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a main part of an air conditioner heat exchanger according to the present invention, and FIG. 2 is a schematic sectional view taken along the line II-II of FIG. This heat exchanger for air conditioning has a large number of plate fins 2.
And a large number of tubes 1 respectively inserted into the tube insertion holes. In this example, the tubes are staggered in two rows. A large number of slits 3 cut and raised in a trapezoidal shape are arranged between the tubes. The tubes 1 in each row are bent in a U-shape, and both straight portions are inserted into the tube insertion holes of the plate fins 2. Next, the tube is expanded by inserting a spreading jig into the tube, and the space between the outer surface of the tube 1 and the tube insertion hole of the plate fin 2 is pressed and fixed. Then, the U-shaped tubes are joined to each other with a U-bend fitting for each row to form a meandering refrigerant flow path. In this example, the refrigerant supply pipes are connected to the refrigerant flow paths in each of the two rows. A forked distribution pipe is attached to an end of the pipe, and the forked side is connected to a flow path for each row to form two refrigerant flow paths. Then, a junction pipe is connected at the final end of the flow path, which is connected to one outlet pipe.

In the air conditioner heat exchanger of the present invention, the tube 1 having an outer diameter of 6 mm is used first, so that the outer diameter of the finished dimension by the expansion is 6.3 mm. The distance d (FIG. 2) between the plate fins 2 is 1.25 mm, and the height of the trapezoidal slit 3 is 0.42 mm.
0.83 mm, and they were alternately arranged as shown in FIG. In addition, in each row of the plate fins 2 in the longitudinal direction, various ones having the first pitch L1 were prepared, and the air-side heat transfer performance at each first pitch L1 was measured. Next, L1 is fixed to the first pitch indicating the maximum value of the transmission performance at that time,
This time, the second pitch L in the width direction of the plate fin 2
2 were variously changed, and the heat transfer performance of each was determined by experiments. FIG. 5 shows a heat transfer characteristic curve with respect to L1, which is a heat transfer tube having an outer diameter D of 6.3 mm. The heat transfer tubes are arranged in two rows in the width direction in a staggered manner. Are formed. The horizontal axis represents the length of the first pitch L1 in the longitudinal direction, and the vertical axis represents HA.
/ ΔPa. Here, H is the air-side heat transfer coefficient (W / m ² K), and A is the air-side heat transfer area (m ² ).
And ΔPa is the air-side pressure loss. As a result, the heat transfer performance was such that the first pitch L1 in FIG.
D is the largest.

Therefore, the first pitch L1 showing the maximum value at that time was fixed at 2.86D, and then the second pitch L2 in the width direction of each tube row was changed. FIG. 6 shows the experimental results. As a result, the second pitch L2 is 1.85D to 4.25D.
And the heat transfer performance is good, and the maximum value is around the 3D at the second pitch L2. Specific numerical values are as follows. At D = 6.3 mm, L1 = 18 mm and L2 = 17 mm, ΔPa = 83 HA = 100 and HA / ΔPa = 1.20. 5 and 6, the outer diameter D of the tube 1 is
6.3mm, then 5.3mm and 6.8mm
Experiments were also performed with the above, but almost the same results were obtained. Therefore,
In the case where the outer diameter is in the range of 5 mm to 7 mm, a conclusion is obtained that the good part of the experimental results of FIGS. 5 and 6 can be adopted. In the above example, the plate fin having the slits 3 formed on the surface is used. However, the plate fin may be cut and raised in a louver shape, or may be formed by bending the plate fin surface in a triangular wave shape. And similar results were obtained. In the case of a slit, the cut-and-raised height was in the range of 0.4 mm to 0.9 mm, and the pitch was 1.0 mm to 2.5 mm. The experiment was conducted with the cut-and-raised height of the louver in the range of 0.4 mm to 0.9 mm. The cut-and-raised pitch of the louver was 2.0 mm to 5.0 mm. The distance d between adjacent plate fins is 1.0 mm to 1.5 mm.
Perform within the range. And in the case of bending into a waveform, the one formed in two peaks per one tube row as shown in FIG.
An experiment was conducted with a bent portion formed by four peaks as shown in FIG. As a result, there was no significant difference between the experimental values.

Next, in the above-mentioned example, the case where the plate fins have two rows has been described. However, an experiment was conducted by preparing a plate fin 2 in which the width of the plate fins 2 was increased by 1.5 times to form a three-row staggered pattern. The result was almost the same as above.

[0011]

The present invention relates to a plate fin type air conditioner heat exchanger, wherein the outer diameter D of a tube inserted into the plate fin is in the range of 5 mm to 7 mm.
The first pitch L1 in the longitudinal direction of the fin is 2.50D to 3.
20D, and the second pitch L2 of each row in the width direction of the fin is formed between 1.85D and 4.25D, so that the heat transfer performance on the air side can be maximized. In addition, in the case where the tubes are arranged in a small number of two or three rows in the width direction of the plate fin, it is possible to provide a high-performance air-conditioning heat exchanger in a small space by using tubes having a relatively small diameter.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of an air-conditioning heat exchanger according to the present invention.

FIG. 2 is a schematic sectional view taken along the line II-II in FIG.

FIG. 3 is a cross-sectional view showing a bent shape of another plate fin 2 of the air-conditioning heat exchanger of the present invention.

FIG. 4 is a cross-sectional view showing a bent shape of still another plate fin of the air-conditioning heat exchanger of the present invention.

FIG. 5 is a curve showing the heat transfer performance on the air side of the air-conditioning heat exchanger of the present invention, in which the horizontal axis represents the first pitch L1 / D in the longitudinal direction of the plate fin.

FIG. 6 is a characteristic curve of the air-conditioning heat exchanger, in which a horizontal axis represents a second pitch L2 / D in a width direction of the plate fin.

FIG. 7 is an enlarged cross-sectional view showing still another plate fin of the air-conditioning heat exchanger of the present invention, in which a louver is cut and raised.

[Explanation of symbols] 1 tube 2 plate fin 3 slit

Claims (5)

[Claims] 1. A large number of tube insertion holes are arranged at positions aligned with each other at regular intervals of a first pitch L1 apart from each other in the longitudinal direction, and at regular intervals of a second pitch L2 at intervals in the width direction. And, having a large number of elongated plate fins arranged in a staggered plurality of rows displaced by a half pitch in the longitudinal direction with respect to the adjacent row, the plate fins are arranged in parallel with each other with a small gap, A tube having a circular cross section is inserted through the tube insertion hole, an airflow flows in the width direction of the plate fin, and a refrigerant having a critical temperature of 90 ° C. or less flows through the tube. The air conditioner according to claim 1, wherein the outer diameter D of the tube is 5 mm to 7 mm, the first pitch L1 is 2.50 D to 3.20 D, and the second pitch L2 is 1.85 D to 4.25 D. For heat exchanger. 2. The tube row according to claim 1, wherein two or three rows of tube insertion holes are formed in the width direction of the plate fins, and the refrigerant flows in parallel in each tube row. Refrigerant piping is connected to the inlet side of the plate via a branch portion, and a large number of louvers or slit cut-and-raised portions are formed parallel to the longitudinal direction on the surface of the plate fin, or a waveform in which a wave travels in the width direction. The distance d between the adjacent plate fins is in the range of 1.0 mm to 1.5 mm, and the cut-and-raised height of the louver or slit is 0.4 mm to
Heat exchanger for air conditioning in the range of 0.9mm. 3. The air-conditioning heat exchanger according to claim 2, wherein the cut-and-raised pitch of the slit is 1.0 mm to 2.5 mm. 4. The air-conditioning heat exchanger according to claim 2, wherein the pitch of the louvers is 2.0 mm to 5.0 mm. 5. The air-conditioning heat exchanger according to claim 2, wherein the wave of the waveform is formed by bending two to four peaks in each unit tube row in the width direction of the plate fin.