Refrigerant evaporator with condensed water drain structure

Details Refrigerant evaporator with condensed water drain structure Refrigerant evaporator with condensed water drain structure

1999-12-09

2001-10-30

Bennett, Henry (Department: 3744)

Refrigeration

With means preventing or handling atmospheric condensate...

Retainer or flow director for atmospheric condensate

C062S515000

Reexamination Certificate

active

06308527

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Application No. 10-351513, filed on Dec. 10, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a refrigerant evaporator with a drain structure, particularly suitable for an automotive air conditioner.
2. Description of the Related Art
As shown in
FIG. 11
, a refrigerant evaporator has plural tubes
2
and corrugated fins
5
respectively disposed between two adjacent tubes
2
and joined thereto. Each of the tubes
2
is composed of two aluminum thin plates
4
, which are joined to each other to form a passage therebetween. Each of the corrugated fins
5
is formed from a corrugated aluminum thin plate, and has louvers, which are cut and bent-up from the plate with a specific angle. The louvers improves a thermal conductive efficiency of the fin
5
. Meandering inner fins
42
,
43
are disposed in and joined to the tubes
2
to improve a thermal conductive efficiency at a refrigerant side.
In the refrigerant evaporator, a central drain groove
10
and a downstream side drain groove
11
are provided at the central portion and a downstream end portion of the tube
2
in an air flow direction A to improve a condensed water draining performance. JP-Y2-4-22225 proposes a similar structure of the evaporator. However, this drain structure is insufficient to drain condensed water from the evaporator. Especially, referring to
FIG. 12
, condensed water produced at the air upstream side fin and flowing on inner surface angular portions
5
c
of bent portions
5
b
of the fin
5
is difficult to be drained and may clog root portions of the louvers
5
a.
FIGS. 14A and 14B
show an experimental result revealing the problem described above. Experimental conditions were 2.0 m/s in flow rate V of air flowing into a core part
3
of the evaporator, 30° C. in temperature of the air, 60% in relative humidity RH of the air, and 4 mm in fin pitch fp of the corrugated fin
5
.
FIG. 14A
shows air flow paths at a dry state where no condensed water is produced on the surface of the corrugated fin
5
, and at a wet state where condensed water is produced on the corrugated fin
5
to clog the louvers
5
a.
At the dry state, since the louvers
5
a
are not clogged with condensed water, air can pass through the louvers
5
a
to the downstream side end. As opposed to this, at the wet state, air cannot pass through the louvers
5
a
provided between a middle portion to the downstream side end of the fin, because condensed water clogs the louvers
5
a.
As a result, as shown in
FIG. 14B
, an air side heat conductivity at the wet state is decreased by approximately 15% as compared to that at the dry state.
On the other hand, recently, a size reduction is required to an automotive air conditioner so that a space for installing the air conditioner in a vehicle compartment is reduced. Therefore, the refrigerant evaporator is also required to be size-reduced especially in the air flow direction A. To comply with this requirement, the refrigerant evaporator must be improved to have higher capacity. Generally, increasing an air side thermal conductivity largely improves the evaporator capacity, and the air side thermal conductivity is increased by decreasing the fin pitch. Decreased fin pitch increases a thermal conductive area. When the fin pitch is decreased, however, water holding capacity of the fin is increased to facilitate the clogging of the louvers by condensed water, resulting in deterioration of fin thermal conductivity.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem. An object of the present invention is to improve drain performance of condensed water and to improve fin thermal conductivity in an evaporator.
According to the present invention, a refrigerant evaporator has a tube defining a passage in which refrigerant flows and having an outer wall with a drain groove for guiding condensed water downward, and a corrugated fin having plural louvers for increasing a contact area with air flowing in an air flow direction and joined to the outer wall of the tube. The corrugated fin has a first fin and a second fin, which are divided by a gap portion facing the drain groove.
The gap portion intercepts flow of condensed water from the first fin, which is disposed at an air upstream side of the second fin in the air flow direction, so that condensed water can be smoothly discharged through the drain groove. Because condensed water produced at the first fin does not flow into the second fin, louver opening portions of the second fin are not clogged with condensed water from the first fin, thereby preventing deterioration of fin thermal conductivity.
The gap portion is required only to intercept the flow of condensed water. That is, the gap portion is not required to form a passage for condensed water. Therefore, a width of the gap portion can be made much smaller than that of the drain groove not to largely decrease a fin thermal conductive area. The first fin and the second fin may be connected with each other via a connecting member crossing the gap portion.


REFERENCES:
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patent: 4621685 (1986-11-01), Nozawa
patent: 5620046 (1997-04-01), Waldhelm et al.
patent: 5669439 (1997-09-01), Hasegawa et al.
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patent: A-9-170850 (1997-06-01), None

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