JP3775302B2 - Heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchanger, and is effective when applied to a heat exchanger that cools air such as an evaporator or a cooler for an air conditioner.
[0002]
[Prior art]
As shown in FIG. 1, a general structure of a heat exchanger that cools air such as an evaporator and a cooler is a wave-like structure joined to a tube 1 through which a cooling medium such as a refrigerant flows and an outer surface of the tube 1. It has a heat exchange core part 3 composed of the fins 2, and the flat part 2 a of the fins 2 has a small temperature boundary layer thickness as shown in FIGS. 2 (a) and 2 (b). In order to promote heat transfer between the air and the fin 2, a louver 2 c is formed by cutting and raising a part of the flat surface portion 2 a into an armor window shape.
[0003]
[Problems to be solved by the invention]
By the way, in recent years, downsizing of the heat exchanger has been eagerly desired, and in order to reduce the size of the heat exchanger without reducing the heat exchange capacity, the heat exchange core portion can be miniaturized by reducing the fin pitch. Therefore, it is necessary to reduce the outer dimension while preventing the heat transfer area with air from decreasing. Then, when the inventors tried to miniaturize the heat exchange core part, the following problems became remarkable.
[0004]
That is, when the air is cooled, condensed water is generated and the condensed water adheres to the surface of the heat exchanger. However, when the fin pitch is sufficiently large, the condensed water attached to the surface of the heat exchanger is caused by surface tension. While it becomes relatively large water droplets and flows downward due to gravity, it is drained, and when the fin pitch decreases and miniaturization proceeds, a space having a size that can form water droplets is secured. Therefore, the condensed water spreads like a film and adheres to the fins due to capillary action.
[0005]
And since this film-like condensed water is hard to flow compared with water-drop-like condensed water, it does not flow downward due to gravity and accumulates so as to spread on the fins 2 as shown in FIG.
[0006]
For this reason, for example, in an air conditioner or the like, when the user increases the air flow rate, the condensed water accumulated so as to spread on the fins 2 flows so as to gather on the leeward side by the wind pressure as shown in FIG. The collected condensed water scatters to the leeward side with the blast air.
[0007]
In addition, as shown in FIG. 7, about 70 to 75% of the total generation amount is generated on the windward side as shown in FIG. 7, and when the air flow rate is small, the condensed water is not drained as described above. Retained. For this reason, when the air flow rate is increased from a small state, a large amount of condensed water collects on the leeward side, so that the problem of scattering of condensed water becomes significant.
[0008]
An object of this invention is to suppress scattering of condensed water, aiming at refinement | miniaturization of a heat exchange core part in view of the said point.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an air cooling heat exchanger in which condensed water is generated by cooling air in the invention according to claim 1 ,
A tube (1) through which air cooling fluid flows ;
Provided on the outer surface of the tube (1), and a fin which is formed in a wave shape having bent portion connecting planar portion adjacent the flat section (2a) and (2a) and (2b) (2),
An armor window-like louver (2c) is formed on the flat surface (2a) ,
The pitch dimension (Fp) of the fin (2) is 3 mm or less,
Furthermore, the louver is a dimension between the tip of the louver (2c) and the tip of the louver (2c) formed in the adjacent flat portion (2a) and the flat portion (2a) where the louver (2c) is formed. The inter-column distance (FLp) is 0.86 mm or more.
[0010]
Thereby, as shown in FIG. 4 to be described later, the condensation of the condensed water can be suppressed while miniaturizing the heat exchange core portion.
[0011]
In the invention described in claim 2, in the heat exchanger according to claim 1, louvers (2c) pitch dimension (Lp) of 0.5mm or more, and wherein the at 1mm or less.
[0012]
Thereby, as shown in FIG. 4 to be described later, the condensation of the condensed water can be suppressed while miniaturizing the heat exchange core portion.
[0014]
According to a third aspect of the present invention, in the heat exchanger according to the first or second aspect, of the outer dimensions of the heat exchanging portion (3) including the tubes (1) and the fins (2), the air flow direction. a parallel portion of the dimension (D) is at 50mm or less, and the height of the fin (2) (h) is characterized by at 7mm or less.
[0015]
Thereby, as shown in FIG. 4 to be described later, the condensation of the condensed water can be suppressed while miniaturizing the heat exchange core portion.
[0017]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the present embodiment, the heat exchanger according to the present invention is applied to an evaporator of a vehicle air conditioner, and the structure thereof is the same as that described in the section “Prior art”.
[0019]
Specifically, as shown in FIG. 1, a tube 1 through which a refrigerant flows, a heat exchange core portion 3 including a wavy fin 2 joined to the outer surface of the tube, and a longitudinal end portion of the tube 1 are provided. And a header tank 4 and the like communicating with each tube 1.
[0020]
The tube 1, the fin 2 and the header tank 4 are all made of an aluminum alloy, and these 1, 2, and 4 are integrated by brazing.
[0021]
Further, as shown in FIG. 2A, the fin 2 has a bent portion 2b that connects the flat portion 2a and the adjacent flat portion 2a, as viewed from the air flow direction, and is formed in a rectangular corrugated shape. As shown in FIG. 2B, an armor window-like louver 2c is integrally formed on the flat surface portion 2a by cutting and raising the flat surface portion 2a.
[0022]
And the evaporator which concerns on this embodiment has the following specifications, It is characterized by the above-mentioned. Incidentally, the numbers in parentheses are specific dimension values employed in the present embodiment.
[0023]
(1) The thickness dimension D of the heat exchange core part 3 is 50 mm or less (38 mm).
(2) The height dimension h of the fin 2 is 7 mm or less (5 mm)
(3) The pitch dimension Fp of the fin 2 is 3 mm or less (2.6 mm).
(4) The pitch dimension Lp of the louver 2c is 0.5 mm or more and 1 mm or less (0.8 mm).
(5) Distance between louver rows FLp is 0.86mm or more (0.86mm)
However, as shown in FIG. 2B, the thickness dimension D of the heat exchange core portion 3 refers to the maximum dimension of the portion parallel to the air flow direction among the external dimensions of the heat exchange core portion 3. As shown in FIG. 2A, the height dimension h of 2 refers to the height difference of the fins 2 formed in a wave shape, that is, the dimension corresponding to the wave amplitude.
[0024]
Further, the pitch dimension Fp of the fin 2 refers to the length of one cycle of the fin 2 formed in a wave shape, that is, the dimension corresponding to the wavelength of the wave, and the pitch dimension Lp of the louver 2c is shown in FIG. As described above, the distance between the upstream end of the air flow and the downstream end of the air flow in one louver 2c is said to be equal to the center-to-center distance between adjacent louvers 2c.
[0025]
The louver row distance FLp is a dimension between the tip of the louver 2c and the tip of the louver 2c formed on the flat surface portion 2a adjacent to the flat surface portion 2a where the louver 2c is formed.
[0026]
In the present embodiment, Fp / 2−Lp × sin (La) is adopted as the louver row distance FLp. La indicates an inclination angle of the louver 2c with respect to the flat surface portion 2a.
[0027]
Next, the function and effect of this embodiment will be described.
[0028]
FIG. 4A shows that the thickness D of the heat exchange core 3 is 38 mm, the core height H when the heat exchange core 3 is viewed from the air flow direction is 211 mm, and the heat exchange core 3 is air. The core width is 280 mm when viewed from the flow direction of the water, and the surface is subjected to deterioration treatment so that the contact angle θ of the condensed water (see FIG. 4B) is 45 ° ± 5 °, and the pitch dimension of the fin 2 It is a test result which shows the relationship between the louver row | line | column distance FLp, the water retention amount hold | maintained at the fin 2, and the scattering start wind speed when Fp is 2.4-3.5 mm.
[0029]
Incidentally, the surface of the heat exchange core part 3 is usually coated with a hydrophilic coating with a resin in order to improve drainage, but the hydrophilicity deteriorates with time, and finally the contact angle θ is increased. It has been empirically found to be about 40 °.
[0030]
As apparent from FIG. 4 (a), when the inter-louver row distance FLp is 0.86 mm or more, the water retention amount is drastically reduced. Therefore, if the inter-louver row distance FLp is 0.86 mm or more, the condensed water is reduced. Scattering can be prevented in advance.
[0031]
In addition, when the distance between the louver rows FLp is 0.86 mm or more, in order for the condensed water to scatter, it is necessary to set the wind speed to 3.5 m / s or more (600 m ³ / h or more in terms of air volume), so the air volume increases. However, practically, the condensed water does not scatter.
[0032]
Note that when the height h of the fin 2, that is, the dimension between the tubes 1 changes, the water retention amount and the absolute value of the splattering start wind speed slightly change. The tendency shown in FIG. 4 is almost the same. Therefore, if the pitch dimension Fp of the fins 2 is 3 mm or less and the louver row distance FLp is 0.86 mm or more, it is possible to prevent the condensed water from splashing.
[0033]
Further, when the pitch dimension Lp of the louvers 2c is reduced, as shown in FIG. 5, the center-to-center distance Lp between adjacent louvers 2c is reduced, so that the amount of condensed water held between the louvers 2c due to surface tension is reduced. Therefore, if the pitch dimension Lp of the louver 2c is 0.5 mm or more and 1 mm or less and the louver row distance FLp is 0.86 mm or more, it is possible to prevent the condensed water from splashing.
[0034]
Moreover, if the thickness dimension D of the heat exchange core part 3 is 50 mm or less, the height dimension h of the fin 2 is 7 mm or less, and the distance between the louver rows FLp is 0.86 mm or more, the heat exchange core part 3 It is possible to prevent the condensate from splashing while exhibiting a heat exchange capability equivalent to that of the heat exchange core part 3 in which the thickness dimension D is 58 mm and the height dimension h of the fin 2 is 10 mm. I have confirmed.
[0035]
As described above, according to the present embodiment, it is possible to prevent the condensate from splashing while reducing the size of the evaporator without causing a decrease in the heat exchange core 3, that is, the heat exchange efficiency. Can do.
[0036]
(Other embodiments)
In the above-described embodiment, the present invention is applied to the evaporator of the vehicle air conditioner. However, the application of the present invention is not limited to this and can be applied to other heat exchangers.
[Brief description of the drawings]
FIG. 1 is a front view of an evaporator according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of fins employed in the evaporator according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram for explaining definitions of terms described in the present specification.
4A is a graph showing the relationship between the distance between the louver rows FLp, the amount of water retained in the fins 2 and the scattering start wind speed, and FIG. 4B is a diagram showing the definition of the contact angle θ.
FIG. 5 is an explanatory diagram for explaining a “problem to be solved by the invention”;
FIG. 6 is an explanatory diagram for explaining “the problem to be solved by the invention”;
FIG. 7 is a graph showing the relationship between the amount of condensed water generated and the dimensions from the front surface of the core.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Tube, 2 ... Fin, 3 ... Heat exchange core part.

Claims (3)

A heat exchanger for air cooling in which condensed water is generated by cooling air,
A tube (1) through which air cooling fluid flows ;
Provided on the outer surface of the tube (1), and a fin which is formed in a wave shape having the planar portion adjacent to the planar portion (2a) (2a) connects the bent portion (2b) (2) ,
An armor window-like louver (2c) is formed on the plane part (2a) ,
The pitch dimension (Fp) of the fin (2) is 3 mm or less,
Furthermore, between the front-end | tip of the said louver (2c), and the front-end | tip of the said louver (2c) formed in the said plane part (2a) adjacent to the said plane part (2a) in which this louver (2c) was formed. A heat exchanger characterized in that a distance between louver rows (FLp) as a dimension is 0.86 mm or more. It said louvers (2c) pitch dimension of (Lp) is 0.5mm or more, the heat exchanger according to claim 1, characterized in that it is 1mm or less. Of the external dimensions of the heat exchanging part (3) including the tube (1) and the fin (2), the dimension (D) of the portion parallel to the air flow direction is 50 mm or less, and the fin ( the heat exchanger according to claim 1 or 2, characterized in that second height dimension of) (h) is 7mm or less.

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