JPS61285388A - Heat exchanger - Google Patents

Abstract

PURPOSE:To permit to reduce pressure drop with good heat transfer efficiency by a method wherein neighboring heat transfer tubes, penetrating plate fins respectively, are constituted positionally to form a substantially regular triangular form and the one side of the triangle is arranged in parallel to the ventilating direction of the heat exchanger in a condenser for a refrigerating device or the like. CONSTITUTION:A multitude of heat transfer bare tubes 2, through which heat medium flow, are arranged in multiple stages and multiple rows so that neighboring three pieces of heat transfer bare tubes A-C are constituted positionally so as to form a substantially regular triangular form and one side of the triangle is arranged in parallel to the ventilating direction (a) of the heat exchanger while a multitude of plate fins 12, through which the heat transfer bare tubes 2 are penetrating, is provided with proper pitches to form the group of heat transfer tubes for the heat exchanger. A cross but 15 is cut at a place of the plate fin 12, which is corresponding to the penetrating hole 14 for the tube 2, and the roots of the triangular sections 13a, which are equally divided into four segments, are bent to form triangular protuberances 13. According to this method, the pressure drop may be reduced extremely without deteriorating heat transfer efficiency in the group of the tubes and miniaturization of a fan or the like may be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a heat exchanger that can extremely reduce the static pressure of a blower without reducing the heat transfer efficiency within the tube group.

"Conventional Technology" Conventionally, in a heat exchanger in which heat transfer bare tubes for passing a heat medium are arranged in multiple stages and in multiple rows, each adjacent heat transfer bare tube, which is a constituent element of various heat transfer tube groups, is arranged in a square shape (substrate 2) Arrange in an array or triangular arrangement (staggered) to form a group of heat transfer tubes, and pass the cooling or cooled gas outside the heat transfer tubes, that is, inside the heat transfer tube group, to exchange heat with the heat medium flowing inside the heat transfer tubes. However, in the case of ventilation perpendicular to a group of heat transfer tubes, A triangular arrangement is often used, in which three adjacent bare heat transfer tubes are arranged in an equilateral triangle or an approximately equilateral triangle, and ventilation is perpendicular to one side of each triangle. Since the gap ST between the heat transfer bare tubes in the row orthogonal to the tube group is small and the flow path area within the tube group is narrow, the wind velocity and mass velocity within the tube group become faster, but conversely, the pressure drop across the tube group increases. However, it did have a major drawback.

"Problems to be Solved by the Invention" By increasing the flow passage area within the tube group in the conventional equilateral triangular or approximate equilateral triangular arrangement (staggered) of heat transfer bare tubes, the wind speed and mass velocity within the tube group are reduced. Nevertheless, the objective is to extremely reduce the pressure drop across the tube group without reducing the heat transfer efficiency within the tube group.

``Means for solving the problem'' The arrangement of the heat transfer bare tubes through which the heat medium of the heat exchanger passes should be changed from the conventionally frequently used equilateral triangular arrangement or approximately equilateral triangular arrangement (staggered) to each adjacent three of the heat transfer bare tubes. The heat transfer bare tubes are arranged in an obtuse isosceles triangle (irregular zigzag), and air is vented by a blower parallel to one side of an equilateral triangle or an approximately equilateral triangle, and perpendicular to the base of the obtuse isosceles triangle. However, in a heat transfer tube formed by penetrating a heat transfer bare tube through a plate fin, a large number of triangular protrusions are formed around the tube hole through which each heat transfer bare tube passes through the plate fin, and a spiral shaped In the heat transfer tube equipped with annular fins, spiral protrusions are formed between the annular fins on the outer surface of the bare heat transfer tube.

"Operation" The heat transfer bare tubes are arranged in a conventional equilateral triangular arrangement or an approximately equilateral triangular arrangement (staggered), and ventilation is carried out perpendicularly to one side of the equilateral triangle or approximate equilateral triangle, to an obtuse isosceles triangular arrangement.
That is, since the irregular staggered pattern is used and ventilation is perpendicular to the base of the obtuse isosceles triangle, the gap S between the heat transfer bare tubes in the row direction perpendicular to the ventilation direction? becomes large and the tube side flow path area can be widened, so that the pressure drop across the tube group, which is proportional to the square of the mass velocity between St', is extremely reduced as ST becomes larger. On the other hand, the tube-side membrane coefficient becomes smaller as the gap SR of the heat transfer bare tube in the step direction parallel to S7 and the ventilation direction becomes larger, but in the present invention, ST is increased and the gaps S and I are made smaller. In addition, in a heat transfer tube in which plate fins are formed on the outer surface of the heat transfer bare tube, a triangular protrusion is formed between each fin, and in a heat transfer tube in which a spiral annular fin is formed on the outer surface of the heat transfer bare tube. In addition, spiral protrusions are formed between the fins on the outer surface of the bare heat transfer tubes, and the shape does not significantly affect the pressure drop in the tube group due to ventilation, so the flow velocity within the tube group can be locally increased. The Reynolds number is increased locally by increasing the speed and generating vortices.
In addition to improving heat transfer within the tube group, that is, on the outer surface of heat transfer bare tubes and on the fin surface, the protrusions on both of the above are directly added as a heat transfer area with high fin efficiency, making it possible to improve heat transfer efficiency. It is.

Embodiments Reference will now be made in detail to the accompanying drawings that illustrate embodiments of the invention.

1 is a main body of the heat exchanger, and 2 is a straight heat transfer bare tube through which a large number of heat mediums are passed.A large number of heat transfer bare tubes 2 are arranged horizontally inside the main body 1, As shown in FIG. 8, a conventional one (staggered) in which three adjacent ABC tubes are arranged in an equilateral triangle shape has a gap S? in the row direction of the heat transfer bare tubes 2 perpendicular to the ventilation direction a? In order to increase this, as shown in Fig. 5, the tube group is arranged by turning the tube group by 90 degrees so that three adjacent ACDs of the heat transfer bare tubes 2 form an obtuse isosceles triangle, that is, in an irregular staggered manner. , both ends of each heat transfer bare tube 2 are connected to tube sheets 3 on both sides of the main body 1,
3 and protrudes through it. 4 is a large number of 180
' At the bend, as shown in FIG. A plurality of upper and lower heat transfer bare tubes 2 in each row constitute independent flow paths. 5 is a heat medium inlet header, 6
is a heat medium outlet header, which connects the protruding ends of the top and bottom heat transfer bare tubes 2 of each row, respectively. The heat medium flows out from the heat medium outlet header 6 through independent flow paths made up of two heat transfer bare tubes 2, respectively. 7 is a blower;
The suction port 9 is installed in the top plate 8 of the main body 1, and the conventional arrangement is from the top plate 8 of the main body 1 in the direction of the bottom frame lO, parallel to the staggered heat transfer bare tube BC, that is, at an irregular staggered obtuse angle. Ventilation is perpendicular to the base CD of the isosceles triangle ACD. Reference numeral 11 denotes a discharge port drilled in the bottom frame 10, which exchanges heat with the heat medium liquid passing through a large number of bare heat transfer tubes 2 with the gas sucked in from the suction port 9, and discharges cooling gas or heated gas. .

Example 1 This example uses plate fin type heat transfer tubes, and the heat transfer bare tubes 2 arranged in an irregular staggered manner are
A large number of plate fins 12 through which each heat transfer bare tube 2 passes are attached at an appropriate pitch P. Reference numeral 13 denotes a triangular projection attached around each heat transfer bare tube 2, and in this embodiment, a tube hole 1 through which each heat transfer bare tube 2 of a large number of plate fins 12 passes.
A cross-shaped cut 15 is made at a location corresponding to 4, and the triangular portion 13a divided into four is bent at the base of the fin 12 of each heat transfer bare tube 2, and a fin 12 is formed between each plate fin 12 and 12. They are formed parallel to each other or at an appropriate angle, and each heat transfer bare tube is designed to measure the area of the tube-side flow passage that is expanded by increasing the gap ST between the heat transfer bare tubes 2 in the direction perpendicular to the ventilation direction a. It shrinks locally around the tube 2, increasing the mass velocity and reducing the equivalent diameter of the heat transfer tube.

Example 2 This example uses annular fins as the heat transfer tube 1, and a strip-shaped fin 16 spirally arranged around the outer circumference of the bare heat transfer tube 2.
a is wound to form an annular fin 16, and the annular fin 16
A large number of heat transfer bare tubes 2 with attached heat transfer tubes 2 are arranged in the above-mentioned irregular staggered pattern.

Reference numeral 16b denotes a spiral projection having a circular cross section in this embodiment, which is wound in a spiral between the band-shaped fins 16a, 16a, and is in contact with the surface of the heat transfer bare tube 2 over the entire circumference similarly to the band-shaped fin 16a. It is an integrated thing. In this case, as the gap S between the heat transfer bare tubes in the direction perpendicular to the ventilation direction a of the irregular zigzag pattern becomes larger, the tube-side flow passage area of each heat transfer bare tube 2 is enlarged.
The spiral protrusion 16b protruding from the surface of the heat transfer bare tube 2 is attached to the triangular protrusion 13 with respect to the extension 17 of the root portion of the annular fin 16 that is created when the band-shaped fin 16a is wound spirally around the fin 16a. This has the same effect as in Example 1, and brings about the same effects as in Example 1.

The present invention has the above configuration, and the heat transfer bare tubes 2 are arranged in an irregular staggered manner in the row direction perpendicular to the ventilation direction a of the instep.
The gap S is seven times that of the conventional staggered equilateral triangular arrangement.For example, if the tube arrangement dimensions of the heat transfer bare tubes 2 of A and B are made as shown in FIG. The passage area is 35% wider than the conventional one, and the flow velocity of the pipe group under the same flow rate is 7.4 m/s for Otsu and 6.7 m/s for A. On the other hand, if the tube-like flow velocity is 4.0.6.0.8.0.10.0 (m
/s) is calculated for a certain gas and temperature, and when these are confirmed through experiments, a graph as shown in Fig. 12 is obtained, and the flow velocity of the tube group under the same flow rate is 6. 7m/s, and Otsu is 7.4m/s, so
According to Figure 12, the extratubular membrane coefficients are 26.5 for the middle and 26.5 for the middle, respectively.
B becomes 24.3 kcal/rrrh"c, which increases by about 13%. Next, calculate the pressure drop in the tube group for A and B when the pressure in the tube group (flow velocity in the tube group) changes in the same way as above. Then, a graph as shown in Fig. 13 is obtained, and the flow velocity of each tube group under the same flow rate is 6.7 m/s.

Since it is 7.4 m/s, the pressure drop within the tube group is 0.9 mm 8q steps, 2.7 mm A47 steps, and the pressure drop in A is reduced to about 1/3 compared to B, but between A and O Since the gap SR between the heat transfer bare tubes 2 in the stages parallel to the ventilation direction is 1:2, the number of stages when the heat transfer bare tubes 2 are arranged as the same heat exchanger is 2:1, and as a result, the tube group The internal pressure drop is reduced by 2/3.

"Effects of the Invention" The present invention arranges a large number of heat transfer bare tubes 2 such that three adjacent heat transfer bare tubes 2 form an equilateral triangle, and one side of the equilateral triangle is perpendicular to the ventilation direction a. The arrangement of the tube group is changed from the staggered arrangement by 90 degrees so that the ventilation is parallel to one side of the equilateral triangle, and the three adjacent bare heat transfer tubes 2 form an obtuse isosceles triangle. Because of the irregular staggered arrangement, the tube side flow path area is 3 times smaller than the conventional arrangement, that is, staggered.
Although it can be made wider by 5% and the flow velocity within the tube group becomes slower, at the same flow velocity within the tube group as in the staggered tube, the outer membrane coefficient is within the range of 4.0 to 10.0 m/s for the applicable intra-tube flow velocity than the conventional one. can be improved by about 13%, and when plate fins 12 are used, the triangular protrusions 13 protruding around each heat transfer bare tube 2, and when annular fins 16 are used, the folds formed at the base of the fins can be improved by about 13%. 17, the expanded tube-side flow path area is locally reduced around each heat-transfer bare tube 2 by the spiral protrusion 16b protruding from the surface of each heat-transfer bare tube 2, and the tube-group flow velocity is reduced. , increase the Reynolds number by generating a vortex flow, increase the mass velocity, and reduce the equivalent diameter of the heat transfer tube to reduce the heat transfer on the two surfaces of the heat transfer bare tube and the 12 and 16 surfaces of the fins. Since it improves heat transfer efficiency, it does not reduce heat transfer efficiency. In addition, since the pressure drop within the tube group is 273 times higher than the conventional staggered arrangement, the power required for the blower 7 can be significantly reduced, and enormous energy savings can be achieved. Furthermore, as described above, in the present invention, the number of stages of heat transfer bare tubes 2 in the direction parallel to the ventilation direction a is approximately twice that of the conventional one, and in order to have the same tube side flow path area as the conventional staggered one, the number of stages of the heat transfer bare tubes 2 in the direction parallel to the ventilation direction a is approximately twice Since the number of rows of heat transfer bare tubes 2 in the direction perpendicular to the 100 mm is reduced, the width of the heat exchanger main body 1 is narrowed, and the installation space of the compartment can be saved.

[Brief explanation of drawings]

The accompanying drawings show embodiments of the present invention, and FIG. 1 is a partially cutaway perspective view of a plate-fin type heat exchanger, and FIG.
The figure is a schematic longitudinal sectional view of the heat exchanger, Figure 3 is a schematic side view as seen from a part of the heat exchanger, and Figure 4 is a dimensional drawing of the tube arrangement. Figures 5 to 8 are from Example 1, and Figure 5 is from A-A in Figure 2.
Figure 6 is an enlarged cross-sectional view of the main part of the line, Figure 6 is a plan view of the main part of Figure 5, Figure 7 is a front view of the main part of the plate fin before the heat transfer bare tube passes through it, and Figure 8 is the conventional plate fin type. FIGS. 9 to 11 are enlarged vertical cross-sectional views of the main parts of the staggered arrangement, and FIG. 9 is an enlarged cross-sectional view of the main parts taken along the line A-A in FIG. The figure is an enlarged cross-sectional view of the main part of the annular fin.
Figure 1 is an enlarged cross-sectional view of the main part of a conventional annular fin arrangement and a staggered arrangement, and Figure 12 shows the outer membrane coefficient of the present invention and the conventional arrangement when the flow velocity in the tube group is changed. Graph showing changes. FIG. 13 is a graph showing changes in pressure drop within the inter-tube group. 1... heat exchanger body, 2- straight heat transfer bare tube, 3-
・One tube plate, 4-180° bend, 5-Heat medium input 16-Heat medium output rohesogoo, 7-Blower, 8...
・Top plate, 9.-Inlet, 10.--Bottom frame, 11.-
-Discharge port, 12--plate fin, 13--triangular projection, 13a-triangular part, 14--tube hole, 15-
Cut, 16... annular fin, 16a-band fin,
16b...Spiral projection, 17-fold, a--ventilation direction.

Claims (1)

[Claims] 1. A large number of heat transfer bare tubes through which a heat medium passes are arranged in multiple stages and in multiple rows so that each three adjacent heat transfer bare tubes constitute an equilateral triangle or an approximately equilateral triangle; A large number of plate fins penetrated by a large number of heat transfer bare tubes are attached to form a heat transfer tube group, and a blower is installed to supply cross-sectional airflow to the heat transfer tube group to ventilate the heat transfer tube group. In a heat exchanger configured to exchange heat between gases, a triangular protrusion is formed around a tube hole through which each heat transfer bare tube passes through a large number of plate fins, and the blower is used to blow each of the three adjacent heat transfer tubes. A heat exchanger characterized in that ventilation is carried out parallel to one side of an equilateral triangle or an approximate equilateral triangle formed by bare thermal tubes. 2. A large number of heat transfer bare tubes through which a heat medium passes are arranged in multiple stages and in multiple rows so that each three adjacent heat transfer bare tubes constitute an equilateral triangle or an approximately equilateral triangle, and the large number of heat transfer bare tubes An annular fin is attached to the outer periphery of the heat transfer tube group in a spiral shape to form a heat transfer tube group, and a blower is installed to supply cross-sectional airflow to the heat transfer tube group to ventilate the heat transfer tube group. In a heat exchanger configured to exchange heat, a spiral protrusion is formed between the annular fins on the outer surface of the heat transfer bare tube, and the air blower is used to form an equilateral triangle formed by each of the three adjacent heat transfer bare tubes. Or a heat exchanger characterized by ventilation parallel to one side of an approximate equilateral triangle.