Heat exchange – Conduit within – or conforming to – panel or wall structure – Means spanning side-by-side tube elements
Reexamination Certificate
1998-07-28
2001-02-27
Flanigan, Allen (Department: 3743)
Heat exchange
Conduit within, or conforming to, panel or wall structure
Means spanning side-by-side tube elements
C165S174000, C062S525000, C062S527000
Reexamination Certificate
active
06192976
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat exchanger used for a refrigeration system, an air conditioner, and so forth, and to a method and an apparatus for fabricating the heat exchanger.
2. Description of the Prior Art
FIG. 64
is a perspective view showing a conventional heat exchanger used for air conditioning disclosed in Japanese Patent Publication (kokai) No. 61-153388, and
FIG. 65
is a sectional view of FIG.
64
. In
FIGS. 64 and 65
, reference numeral
1
means heat transfer tubes, and
2
is small-gage wires connected to the heat transfer tubes
1
so as to serve as a fin. Reference mark A means out-tube operating fluid (such as air), and B is in-tube operating fluid (such as coolant). In the heat exchanger, the small-gage wires
2
thread through the heat transfer tubes
1
disposed in parallel, and mutually intersect. That is, the heat exchanger has a mesh-type structure including the heat transfer tubes
1
serving as the warp, and the small-gage wires
2
serving as the weft.
A description will now be given of the operation. As shown in
FIG. 65
, in the heat exchanger used for air conditioning in the conventional embodiment, when the out-tube fluid A flows between the small-gage wires
2
threading through the heat transfer tubes
1
, the small-gage wires
2
disturb a flow of the out-tube fluid A. That is, as shown by the arrow of
FIG. 65
, the out-tube fluid A flowing directly below the small-gage wire
2
collides with the small-gage wire
2
, and is divided into right and left flows. Besides, there is another flow of the out-tube fluid A upward moving on a surface of the heat transfer tube
1
along the small-gage wire
2
. This results in a long contact time between the out-tube operating fluid A and the heat transfer tubes
1
, that is, a long contact time between the out-tube operating fluid A and the in-tube operating fluid B.
In order to fabricate such a heat exchanger, the small-gage wires
2
may thread through the plurality of heat transfer tubes
1
disposed in parallel with the small-gage wires
2
mutually intersecting. That is, the heat exchanger is assembled to have the mesh-type structure including the heat transfer tubes
1
serving as the warp, and the small-gage wires
2
serving as the weft. Further, after the assembly of the mesh-type structure, contact portions between the heat transfer tubes
1
and the small-gage wires
2
are welded one by one in order to enhance thermal conductivity.
FIG. 66
shows another conventional embodiment, i.e., a plate fin-type heat exchanger used for a room air conditioner and so forth. For assembly of the heat exchanger, instead of the small-gage wires
2
serving as a fin, plate-type fins are mounted at interval of about 1 to 5 mm. Further, a heat transfer tube
1
is inserted into a hole provided in the fin, and after the insertion, fluid is introduced into the heat transfer tube
1
with pressure. Thereby, a diameter of the heat transfer tube
1
is expanded to bring the heat transfer tube
1
into tight contact with the plate fin
102
.
In the plate fin-type heat exchanger, the out-tube operating fluid A can flow along the plate fin without large turbulence, resulting in reduced thermal conductivity.
In recent years, a diameter of the heat transfer tube has been decreased in order to provide a more compact and higher-performance heat exchanger. However, when the narrow heat transfer tube is applied to the heat exchanger (in particular, an evaporator), a higher pressure loss is caused in a coolant flowing in the tube, resulting in a reduced performance of an air conditioner. Hence, in a typical method, the number of path of the heat exchanger is increased to decrease an amount of circulating coolant per path, thereby avoiding the reduction of performance.
Typically, a branch pipe may be used for several paths. For several tens to several hundreds paths, in many cases, an inlet header and an outlet header are mounted, and a plurality of heat transfer tubes are disposed between the headers so as to provide a multi-path heat exchanger (evaporator).
FIG. 67
is a sectional view of a conventional multi-path evaporator disclosed in Japanese Patent Publication (Kokai) No. 6-26737. In the drawing, reference numeral
3
a
means an inlet header, and
3
b
is an outlet header. Reference numeral
45
means inlet coolant piping. The inlet coolant piping is a straight pipe whose length is equal to or less than twenty times a bore diameter of an expansion valve
58
, and an irregular surface
61
is provided in the inlet coolant piping
45
.
FIGS. 68 and 69
are font views of a conventional gas-liquid separating heat exchanger disclosed in Japanese Patent Publication (Kokai) No. 6-117728. In
FIG. 68
, an opening in a lower inlet header
3
a
is coupled with an opening in an upper outlet header
3
b
through a gas-liquid separating cylinder
63
having a predetermined length. Further, reference numeral
2
means a plurality of mesh fins mounted to heat transfer tubes
1
in a direction perpendicular to a heating surface, and
64
is a throttle valve mounted to avoid a counter-flow in the vicinity of a connecting portion of the outlet header
3
b
to the gas-liquid cylinder
63
. A gas-liquid two-phase coolant flows through inlet coolant piping
45
, and is vertically divided into two phases, i.e., an upper gaseous phase and a lower liquid phase, by a difference in gravity therebetween in the gas-liquid separating cylinder
63
. The gas coolant is bypassed through the outlet header
3
b,
and only the liquid coolant is supplied into the heat transfer tubes
1
through the inlet header
3
a.
Thus, the liquid can uniformly be distributed to paths.
As shown in
FIG. 69
, a float pipe
66
vertically passes through the gas-liquid separating cylinder
63
to form a liquid level controller
65
. Further, a cylindrical float
67
is fitted into the float pipe
66
so as to vertically move according to a variation in liquid level of the liquid coolant in a gas-liquid separating chamber. A plurality of openings
68
and
69
are provided in both upper and lower ends of the float pipe
66
. In such a structure, the gas coolant can be bypassed through the openings
68
in the upper end to the outlet header
3
b.
FIG. 70
is a sectional view of a conventional multi-path evaporator disclosed in Japanese Patent Publication (Kokai) No. 6-159983. In the drawing, a plurality of coolant dispersing holes
71
are provided in a peripheral wall of a coolant dispersing tube body
70
, and the coolant dispersing tube body
70
is disposed in an inlet header
3
a.
A liquid coolant introduced into the inlet header
3
a
through the coolant dispersing holes
71
can be distributed to the heat transfer tubes
1
.
FIG. 71
is a front view of a conventional multi-path evaporator disclosed in Japanese Patent Publication (Kokai) No. 6-101935. In the drawing, a plurality of heat transfer tubes
1
are vertically disposed in parallel to each other, and an inlet header
3
a
and an outlet header
3
b
are connected through the heat transfer tubes
1
. Further, an upper portion of the inlet header
3
a
and an upper portion of the outlet header
3
b
are communicated through a gas bypass pipe
72
.
The conventional heat exchanger used for air conditioning has the above structure. In the heat exchanger used for air conditioning, the heat transfer tube itself has a narrow width in the range of 1 to 5 mm. The heat exchanger has greater heat transfer coefficient than that of a heat exchanger used in a conventional room air conditioner. However, for the same front surface area, the heat exchanger has too small heating surface area which is equal to or less than one fifth of a heating surface area of the heat exchanger used in the conventional room air conditioner. Consequently, there is a problem in that a required amount of heat exchange can not be obtained. In order to overcome the problem, it can be considered to use a plurality of rows of heating surfaces. However, when the conventional heat excha
Gotoh Takashi
Ikejima Kaoru
Motizuki Atsushi
Sueto Yuji
Takeshita Michimasa
Burns Doane , Swecker, Mathis LLP
Flanigan Allen
Mitsubishi Denki & Kabushiki Kaisha
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