JPH0686993B2 - Heat exchanger with fins - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an outdoor finned heat exchanger of a heat pump type air conditioner using air as a heat source.

2. Description of the Related Art In the heating operation of a heat pump type air conditioner that uses air as a heat source, the outdoor heat exchanger functions as an evaporator, and when the ambient air temperature decreases, the evaporation temperature becomes 0 ° C. or less, and water vapor in the air becomes frost. Adheres to form a frost layer. Defrosting is necessary because the amount of air passing through the frost layer and the amount of heat exchange due to the adiabatic effect significantly decrease.

Therefore, the conventional outdoor heat exchanger is, as shown in FIG.
A tube group 2 which is installed horizontally and through which a refrigerant flows, and a tube group 2 which is vertically inserted into the tube group 2 at regular intervals and air is drawn between them by an arrow 1
Consists fin group 4, 5 flowing in the direction, the fin spacing S ₁ of fin group 4 of the air inlet side and that of fin group of the outlet-side
_They were arranged more sparsely (S ₁ > S ₂ ) than S ₂ .

Problems to be Solved by the Invention Due to such a configuration, it was expected that the operating time until the fins on the air inflow side where the amount of frost is the largest is blocked by the frost layer is lengthened. The driving time is not too long. The reason is considered as follows. In practice,
When determining the fin spacing between the fin groups 4 and 5 and S ₁ and S ₂ , in order to secure the heat exchange amount of the entire heat exchanger, the total number of fins of the fin groups 4 and 5 is set, that is, all fins. The surface area cannot be reduced so much. Therefore, if S ₁ is increased, S ₂ needs to be very small. However, in this case, the fin group 5 is closed earlier by the frost layer (this state is shown in FIG. 3. 3 is the frost layer), and the operation time is longer than that with a constant fin interval. On the contrary, it has no superiority. For this reason, it is necessary to set the fin interval such that the fin group 4 and the fin group 5 are blocked by the frost layer almost at the same time without increasing the difference between S ₁ and S ₂ so much. However, with such a fin spacing setting,
S ₁ cannot be increased so much, and the advantage is not so great compared to the case where the fin spacing is constant.

In view of the above problems, the present invention does not increase the difference in the fin spacing between the air inflow side fin group with a narrow fin spacing and the air outflow side fin group with a narrow fin spacing without increasing the frost of the fin group. It provides a means to slow down layer blockage.

Means for Solving the Problems In order to solve the above problems, the present invention comprises a group of tubes through which a refrigerant flows, and a group of fins inserted into the group of tubes and through which air flows, The fin groups of each row are independent from each other in the direction of air flow, and the fin intervals of the fin groups of each row are sequentially arranged from the air inflow side to the outflow side in a sparse to dense manner, and the air inflow side rows of the fin group are arranged. The surface of the fins is made water repellent, and the surfaces of the fins in the other rows are made hydrophilic.

Effect According to the research conducted by the inventors, when the water-repellent surface becomes 0 ° C. or less and moisture in the air adheres, it does not suddenly frost even when the surface temperature is considerably low, and once adheres as condensed water to form droplets. It is retained for a long time as a liquid liquid. afterwards,
Water freezes, frost adheres to it, and frost forms. For this reason, by making the fin surface of the air inflow side fin group water-repellent, concentrated moisture in the air adheres to the fin surface as liquid moisture having a density several times higher than that of frost. This moisture eventually freezes, and then the concentrated moisture in the air adheres as frost on the frozen water, but until then, a large air passage between adjacent fins is secured.
As a result, by making the surface of the fin group on the air inflow side water-repellent, it is possible to cause the frost layer to close the fin group on the air inflow side without making the fin interval so large. On the other hand, since the air outflow side fin group can secure the entire fin surface area without reducing the fin interval so much, it is possible to delay the blockage due to the frost layer in the air outflow side fin group, and the heat exchanger as a whole, Blockage due to the frost layer can be delayed.

Example A heat exchanger with fins according to an example of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 11 is an air inflow direction, 12 is a tube group, 13 is a frost layer, 13 'is condensed water (liquid), and 14 and 15 are independent fin groups. The surface of the fin group 14 is water-repellent, and the surface of the fin group 15 is hydrophilic.

The operation of the finned heat exchanger configured as described above will be described below with reference to FIG.

The air flowing into the fin group 14 is cooled and condensed on the fin surface, but since the fin surface is water-repellent, even if the fin surface temperature is 0 ° C. or less, the fin surface does not freeze,
It is retained by liquid moisture. Compared to the frost layer, the liquid water content is
The density is several times higher, and the fin group 14 does not easily close. On the other hand, the air flowing out from the fin group 14 flows into the fin group 15. Since the fin surface of the fin group 15 is hydrophilic, moisture in the air immediately frosts and a frost layer develops when the fin surface temperature is 0 ° C or lower. However, the air flowing into the fin group 15 has already been dehumidified considerably by the fin group 14, and the fin interval of the fin group 15 is relatively large, so that the fin group 15 is blocked by the frost layer. It takes time. For this reason, the time taken to block the frost layer in the heat exchanger as a whole is significantly extended.

On the other hand, under operating conditions where the fin surface temperature is 0 ° C or higher, condensed water (liquid) adheres to the fin surfaces of both fin groups 14 and 15, but in the fin group 14, since the fin interval is large, Water does not bridge between the fins, which does not cause an increase in ventilation resistance. Further, although the fin spacing of the fin group 15 is small, moisture does not bridge because the fin surface is hydrophilic.

As described above, according to this embodiment, the fin group on the air inflow side
Delaying the closing of the fin group by the frost layer by increasing the fin interval of 14 and making the fin surface water repellent, reducing the fin interval of the air outflow side fin group 15 and making the fin surface hydrophilic. You can

EFFECTS OF THE INVENTION As described above, the present invention includes a tube group in which a refrigerant flows inside and a fin group inserted in this tube group and in which air flows, and the fin groups are provided with respect to the flow direction of air. The fins of each fin group of each row are arranged in order from the air inflow side to the outflow side in a sparse to dense manner, and the fin surface of the air inflow side row of the fin group is water repellent, etc. By making the fin surface of the row of (3) hydrophilic, the blockage of the fin group by the frost layer can be delayed.

[Brief description of drawings]

1 is a perspective view of a finned heat exchanger according to an embodiment of the present invention, FIG. 2 is a partial plan view of FIG. 1 during frost formation, and FIG. 3 is a conventional finned heat exchanger frost formation. It is a partial top view at the time. 12 …… Tube group, 13 …… Frost layer, 13 ′ …… Condensed water (liquid), 14
...... Air inlet side fin group, 15 ...... Air outlet side fin group.

Claims (1)

[Claims] 1. A group of tubes in which a refrigerant flows, and a group of fins inserted into the group of tubes and in which air flows between the groups of tubes, wherein the groups of fins are independent of each other in the direction of air flow. , The fin intervals of the fin groups in each row are sequentially arranged from the air inflow side to the outflow side in a sparse to dense manner, and the fin surfaces of the air inflow side rows of the fin groups are water repellent, and the fin surfaces of other rows Heat exchanger with fins that is hydrophilic.