Fin and tube type heat exchanger

Details Fin and tube type heat exchanger Fin and tube type heat exchanger

2000-08-25

2001-12-04

Lazarus, Ira S. (Department: 3743)

Heat exchange

Radiator core type

Side-by-side tubes traversing fin means

C165S182000

Reexamination Certificate

active

06325140

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fin and tube type heat exchanger, and more particularly, to a fin tube heat exchanger of a compact type, for reducing a production cost, enhancing a heat exchange efficiency compared to a related art heat exchanger, and reducing power consumption of a motor coming from a pressure loss.
2. Background of the Related Art
FIGS. 1 and 2
illustrate fin tube type heat exchangers. The fin tube type heat exchanger is provided with a plurality of fins stacked perpendicular to heat exchange tubes
10
, to enlarge a heat exchange surface for enhancing a heat exchange effect. There are a plurality of coupling holes
21
in a surface of the fin along a long side direction of the cooling fins
20
, through which the heat exchange tubes
10
are passed. The coupling holes are formed in two rows in zigzag in an upper step and in a lower step of the cooling fins. A space between adjacent coupling holes
21
on the same step is opened for an air flow(a short side direction of the cooling fin), and the space has a plurality of projections
22
formed reciprocally in a front and a rear surfaces thereof for guiding the air flow that passes respective cooling fins. Therefore, the refrigerant flowing in from a refrigerant inlet of the heat exchange tubes
10
passes inside of the heat exchange tubes, to cool down the heat exchange tube
10
and drop a temperature of the heat exchange tubes, and, on the same time with this, a heat source (air) provided from outside of the heat exchanger is passed between the cooling fins
20
by rotation of a fan(not shown), so that the air passed between respective cooling fins makes heat exchange with the refrigerant through the heat exchange tubes
10
, the cooling fins
20
and the projections
22
. And, the turbulence caused by the projections
22
as the air hits onto the projections
22
during the air passes through openings of the projections
22
enhances the heat exchange effect.
In the meantime, design criteria of the aforementioned related art heat exchanger are fixed to maximize the heat exchange efficiency. Taking the fact that a thermal resistance on a side external air flows is higher than a thermal resistance inside of the heat exchange tube into account, a difference of the thermal resistances can be reduced by enlarging a heat exchange surface on the side the external air flows. For this, a center distance between adjacent coupling holes
21
on the same row in the cooling fin
20
(called as “step pitch S”) is set in terms of the tube diameter D
0
to be 2.5 D
0
≦S
1
≦3.0 D
0
and a width of the cooling fin
20
(or a distance between adjacent steps when the cooling fin has at least two steps of the coupling holes)(called as “row pitch L
1
, ”) is set in terms of the tube diameter D
0
to be 1.2 D
0
≦L
1
≦1.8 D
0
. Considering that generally used diameters of the tube
10
are 9.52 mm or 7 mm, the heat exchanger with the tube diameter D
0
9.52 mm is designed to have the step pitch S
1
to be within a range of 2.5~2.7 D
0
and the row pitch L
1
to be in a range of 1.8 D
0
. And, the heat exchanger with the tube diameter D
0
7 mm is designed to have the step pitch S
1
to be in a range of 3 D
0
and the row pitch L
1
to be in a range of 1.2 D
0
. As the foregoing configurations of the heat exchanger has small ranges of the step pitches S
1
and the row pitches L
1
, compared to the tube diameters D
0
, an improvement of the heat exchange performance can be achieved when an air flow rate is the same.
However, the small ranges cause a higher pressure loss on the air side. That is, the high air flow speed required for the improvement of the heat exchange performance causes an increased noise, but a configuration of the tubes designed to reduce the noise drops the heat exchange performance. Because a power of a fan motor (not shown) should be increased for obtaining the same air flow rate in a state the pressure loss on the air side is increased, a power consumption can not, but be increased, and damage to the fan motor can be caused.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a fin tube heat exchanger that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a fin tube heat exchanger which has an optimal design that can prevent an air side pressure loss, maintain a hest exchange performance to an appropriate state, reduce a heat exchanger maintenance cost, and save an overall heat exchanger fabrication cost.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the fin tube heat exchanger includes heat exchange tubes each having an inside for flow of fluid therethrough, and sheets of cooling fins stacked at fixed intervals each having the heat exchange tubes passed therethrough in a step pitch L
2
, a direction along an air flow, in a range of 1.8 D
0
≦L
2
≦2.2 D
0
and in a row pitch S
2
, a direction perpendicular to the air flow, in a range of 3.3 D
0
≦S
2
≦4.5 D
0
, where D
0
denotes a diameter of the heat exchange tube, and protection pieces between the tubes opened for the air flow.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.


REFERENCES:
patent: 4723600 (1988-02-01), Yokoyama et al.
patent: 5170842 (1992-12-01), Kato et al.
patent: 5706885 (1998-01-01), Kim
patent: 5975198 (1999-11-01), Kim et al.
patent: 6227289 (2001-05-01), Yokoyama et al.

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