The present invention relates to a heat exchanger and an air conditioner provided with this heat exchanger.
A prior-art heat exchanger constituting an air conditioner includes a heat exchanger called fin-tube heat exchanger. This heat exchanger is constituted by plate-like fins arranged with a certain interval and through which gas (air) flows and a flat-shaped heat transfer pipe inserted orthogonally into the plate-like fins and through which a refrigerant flows, and a plurality of protruding strips are provided in the axial direction on an inner face of the heat transfer pipe (See Patent Document 1, for example). Also, a heat exchanger having a flat-shaped heat transfer pipe in a multi-hole structure or a heat exchanger having a plurality of slits provided in a plate-like fin by cutting are included. The slit group is provided so that a side end portion of the slit opposes a flow direction of air, and it is described that by thinning a speed boundary layer and a temperature boundary layer of the air flow at the side end portion of the slit, heat transfer is promoted and heat exchange capacity is increased (See Patent Document 2, for example).
In the heat exchanger of Patent Document 1, since the heat transfer pipe is formed in a flat elliptic shape having a single through hole through which a refrigerant flows, the heat transfer pipe is expanded and deformed by a pressure inside the heat transfer pipe during an operation of a refrigerating system, there is a problem that close contact between the heat transfer pipe and the plate-like fin is deteriorated.
With the purpose of improving performance of the heat exchanger, the heat transfer pipe can be made into a multi-hole structure and its size and diameter can be reduced as in Patent Document 2. However, by reducing the size and diameter of the heat transfer pipe, heat transfer rate in the pipe is increased while pressure loss is increased, and they need to be optimized. Also, the heat transfer pipe whose size and diameter are reduced is advantageous in heat transfer performance, but there is a problem that a cost for assembling or the like is increased since manufacture of the heat transfer pipe and mounting between the heat transfer pipe and the plate-like fin are carried out by brazing.
The present invention was made in order to solve the above problems and has an object to provide a heat exchanger and an air conditioner provided with this heat exchanger in which ventilation resistance is reduced and heat exchange capacity is increased by using a heat transfer pipe in which deformation of the heat transfer pipe caused by a pressure inside the heat transfer pipe does not occur even if the heat transfer pipe is made flat, close contact with the plate-like fin is favorable, assembling performance is good, and heat transfer performance is excellent.
A heat exchanger according to the present invention is provided with a plurality of plate-like fins arranged in parallel with a predetermined interval and a plurality of flat-shaped heat transfer pipes inserted in a direction orthogonal to the plate-like fins and through which a refrigerant flows, and the heat transfer pipe has an outside shape with a flat outer face arranged along an air flow direction and a section substantially in an oval shape and first and second refrigerant flow passages made of two symmetric and substantially D-shaped through holes having a bulkhead between the two passages inside, which is bonded to the plate-like fin by expanding diameters of the first and second refrigerant flow passages by a pipe-expanding burette ball.
According to the present invention, since the bulkhead partitioning the two refrigerant flow passages are provided inside the flat-shaped heat transfer pipe, deformation of the heat transfer pipe is not caused by a pressure inside the heat transfer pipe even if the heat transfer pipe is made flat, and a heat transfer pipe in which close contact with the plate-like fin is favorable, assembling performance is good and heat transfer performance is excellent can be obtained. Also, by using the flat-shaped heat transfer pipe with excellent heat transfer performance with reduced size and diameter, such a heat exchanger can be obtained in which ventilation resistance is reduced and heat exchange capacity is increased.
Embodiments of the present invention will be described below referring to the attached drawings.
The heat transfer pipe 3 is formed such that, as shown in
A radius r after diameter expansion (which will be described later) of the first, second refrigerant flow passages 31a, 31b made of such substantially D-shaped through holes is 1 to 3 mm. That is because if the radius r is less than 1 mm, an increase amount of pressure loss becomes larger than an increase amount of heat transfer rate, which results in lowered heat exchange performance. On the other hand, if the radius r exceeds 3 mm, not only that an inter-pipe refrigerant flow velocity is slowed and the heat exchange performance is lowered but that a height (thickness) H and a width W of the flat-shaped heat transfer pipe 3 are increased and the pressure loss of the air flow is increased. Thus, the radius r after the diameter expansion of the first, second refrigerant flow passages 31a, 31b is set at 1 to 3 mm (the same applies to the radius r of the refrigerant flow passage in the other embodiments).
Subsequently, an example of a diameter expansion procedure of the first, second refrigerant flow passages 31a, 31b of the above flat-shaped heat transfer pipe 3 and a mounting procedure to a mounting hole (long hole) 22 provided in the plate-like fin 2 will be described.
As shown in
In this case, a thickness t2 of the bulkhead 32 of the first, second refrigerant flow passages 31a, 31b is preferably formed thicker about 1.5 times a thickness t1 of the first, second refrigerant flow passages 31a, 31b. As a result, pressure capacity of the flat-shaped heat transfer pipe 3 can be increased.
As mentioned above, according to the heat transfer pipe of this embodiment, since the pressure capacity of the flat-shaped heat transfer pipe 3 can be maintained by the bulkhead 32 provided between the first, second flow passages 31a, 31b, the flat-shaped heat transfer pipe 3 is not deformed by the pressure inside the heat transfer pipe and the close contact with the plate-like fin 2 can be kept favorable. Thus, the heat transfer pipe with excellent heat transfer performance can be obtained. Also, since the flat-shaped heat transfer pipe 3 is bonded to the plate-like fin 2 by pipe expansion, assembling is far easier than brazing. Therefore, a manufacturing cost can be lowered. Moreover, an interval between the plate-like fins 2 can be kept constant by the fin collar portion 21 in the same direction and close contact between the flat-shaped heat transfer pipe 3 and the plate-like fin 2 is favorable, the heat exchanger in which the ventilation resistance is reduced and heat exchange capacity can be increased can be obtained even if the heat transfer pipe is made flat and the size and diameter are reduced.
The above flat-shaped heat transfer pipe 3 is inserted into the mounting hole 22 of the plate-like fin 2 according to the above-mentioned procedure and fixed to the plate-like fin 2 by expanding the diameters of the first, second refrigerant flow passages 31a, 31b through each protruding strip 33 using the pipe-expanding burette balls 100 having the same sectional shape (substantially D-shape) as above.
As shown in
In other words, the first, second refrigerant flow passages 31a, 31b on which the plurality of protruding strips 33, 34 are provided are constituted so that a distance from predetermined points at the center parts of the refrigerant flow passages in the section (O1, O2 in
This flat-shaped heat transfer pipe 3 is inserted into the mounting hole 22 of the plate-like fin 2 as shown in
This flat-shaped heat transfer 3 is inserted into the mounting hole 21 of the plate-like fin 2 according to the above-mentioned procedure and fixed to the plate-like fin 2 by expanding the diameter of the first refrigerant flow passage 31a using the pipe-expanding burette ball 41 having a substantially D-shaped section and by expanding the diameter of the second refrigerant flow passage 31b using the pipe-expanding burette ball 41 having a circular section. In this case, the height h (protruding length) of the protruding strip 33 is preferably approximately 0.1 to 0.3 mm. The sectional shape of the protruding strip 33 is not limited to a square, but any appropriate sectional shape such as triangle, trapezoid, semicircle and the like can be employed.
According to this embodiment, the first embodiment and the third embodiment are applied in combination to the first, second refrigerant flow passages 31a, 31b, and the effect substantially similar to these embodiments can be obtained. That is, the flat-shaped heat transfer pipe 3 is not deformed by the pressure inside the heat transfer pipe, and close contact with the plate-like fin 2 can be maintained favorable. Thus, the heat transfer pipe having excellent heat transfer performance can be obtained. Also, since the flat-shaped heat transfer pipe 3 is bonded to the plate-like fin 2 by pipe expansion, assembling is far easier than brazing. Therefore, a manufacturing cost can be reduced. Moreover, since each of the plate-like fins 2 can be maintained with a constant interval by the fin collar portion 21 in the same direction and close contact between the flat-shaped heat transfer pipe 3 and the plate-like fin 2 is favorable, even if the heat transfer pipe is made flat or reduced in size and diameter, a heat exchanger in which ventilation resistance is reduced and heat exchange capacity can be increased can be obtained.
Also, if the plurality of protruding strips 33, 34 are provided on the inner wall face of the refrigerant flow passage 31b, either of the refrigerant flow passages, a contact area with the refrigerant is increased, and since the height h of the protruding strip 33 is set at approximately 0.1 to 0.3 mm, a pressure inside the flow passage is not increased but the heat transfer performance can be further improved.
First,
Subsequently a flow of refrigerant of the prior-art fin-tube heat exchanger 50 will be described. The refrigerant enters from an inlet pipe 52, flows out from “a” on the front face side to “b” on the back face side, flows in from “c” through the hairpin pipe 51 and flows out to “d” on the front face side, passes through the return bend pipe 5 on the front face side, and flows into the hairpin pipe 51 in the subsequent stage from “e”. As mentioned above, the refrigerant fluidizes downward through the heat transfer pipe as a→b→c→d→e→f→g→ . . . , and the refrigerant finally flows out of a flow-out pipe 53 on the lower stage. During that period, heat exchange is performed with air passing between the plate-like fins 2.
On the other hand, with regard to the heat exchanger 1 of this embodiment, as shown in
In the heat exchanger 1 of this embodiment, the refrigerant separately flows into the first, second refrigerant flow passages 31a, 31b of the heat transfer pipe 3 on the first stage, respectively, at the same time. The refrigerant flowing into the first refrigerant flow passage 31a of the heat transfer pipe 3 on the first stage flows out of the first refrigerant flow passage 31a of the heat transfer pipe 3 on the second stage through the hairpin pipe 30 and flows into the second refrigerant flow passage 31b of the heat transfer pipe 3 on the third stage further through the return bend pipe 5a. On the other hand, the refrigerant flowing into the second refrigerant flow passage 31b of the heat transfer pipe 3 on the first stage flows out of the second refrigerant flow passage 31b of the heat transfer pipe 3 on the second stage through the hairpin pipe 30 and flows into the first refrigerant flow passage 31a of the heat transfer pipe 3 on the third stage further through the return bend pipe 5b.
Therefore, according to the heat exchanger 1 of this embodiment, since the refrigerant fluidizes alternately in a cross state by the return bend pipes 5a, 5b, the heat exchange capacity on the upwind side and the heat exchange capacity on the downwind side can be well-balanced, and a heat exchanger with high efficiency can be obtained.
As a result, a mass ratio of a gas phase and a liquid phase becomes the same at outlet sides of the plurality of refrigerant circuits of the heat transfer pipe and it enters the refrigerant inlet portion of the heat transfer pipe on the subsequent stage, the heat exchange capacity on the upwind side and the heat exchange capacity on the downwind side can be well-balanced, and a heat exchanger with high efficiency can be obtained.
Also, the heat exchanger 1 constituted by using the flat-shaped heat transfer pipe 3 of each of the above embodiments can be used, in a refrigerating cycle circuit constituted by sequentially connecting compressor, condenser, throttle device, evaporator by piping, as the condenser or evaporator using a HC single refrigerant of a mixed refrigerant containing HC or a refrigerant of any of R32, R410A, R407C, carbon dioxide and the like as an operating fluid.
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Number | Date | Country | |
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20150033789 A1 | Feb 2015 | US |
Number | Date | Country | |
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Parent | 12994193 | US | |
Child | 14515994 | US |