Heat exchange – With first fluid holder or collector open to second fluid – Trickler
Reexamination Certificate
2001-04-13
2004-01-27
Flanigan, Allen (Department: 3743)
Heat exchange
With first fluid holder or collector open to second fluid
Trickler
C165S167000
Reexamination Certificate
active
06681844
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a plate type heat exchanger, and more particularly to a plate type heat exchanger for exchanging heat between two fluids flowing alternately through adjacent fluid passages between piled plates, which is suitable for such cases where at least one of the fluids flows as a liquid film on a surface of the plate, or is a low-pressure vapor, as an evaporator in a refrigerating machine, or an evaporator or a low-temperature regenerator in an absorption refrigerating machine.
BACKGROUND ART
A conventional plate type heat exchanger is of a small size for a heat load, and can cope with an increased heat load by increasing the number of piled plates having the same shape, so that the plate type heat exchanger is frequently used as a heat exchanger.
The conventional plate type heat exchanger is shown in FIG.
16
. As shown in
FIG. 16
, two plates
1
,
1
′ having opening portions
5
,
6
at both ends thereof are piled on each other so as to form a space R
1
therebetween, and peripheral portions of the plates are sealed to form a heat exchange element
2
. The heat exchange elements
2
are piled on and bonded to each other in such a state that the opening portions
5
,
6
communicate with each other, thereby forming a heat exchange structure. This heat exchange structure is housed in a shell, and fluids flow inside and outside the heat exchange elements
2
so as to exchange heat with each other. A corrugated or fin-shaped plate
42
is mounted within the space R
1
in the heat exchange element
2
to increase the strength of the plates and promote heat exchange by turbulence of a flow. The upper and lower opening portions
5
,
6
are projected in a cylindrical form so as to be fitted to each other.
In this type of heat exchanger, an inlet and an outlet for a first fluid passing through the shell are connected to the opening portions
5
,
6
. The first fluid flows in parallel through the respective heat exchange elements
2
as indicated by arrows. On the other hand, a second fluid flows from an inlet and an outlet for the second fluid, which are provided in the shell, into a space R
2
formed outside the heat exchange elements
2
. The outside space R
2
can be made wider than the inside space R
1
. Therefore, when a fluid involving a phase change is used as the second fluid, the heat exchanger can cope with a volume change in accordance with the phase change. Further, the inlet and outlet for the outside space R
2
can be made larger than the inlet and outlet for R
1
. Therefore, the heat exchanger can cope with a fluid that is a low-pressure vapor having a large specific volume. The outside space R
2
can be made wider than the inside space R
1
depending upon the shapes of projections and depressions of the plates, so that the heat exchanger can cope with even a lower-pressure vapor.
To manufacture such a heat exchanger, the turbulence plate.
42
is mounted and positioned on the upper plate
1
. Then, the lower plate
1
′ is placed on the turbulence plate
42
, and the peripheral portion of the lower plate
1
′ is folded to be bonded to the upper plate
1
, for thereby forming the heat exchange element
2
. Next, the adjacent heat exchange elements
2
are connected to each other so that cylindrical communicating portions
7
are fitted to each other, for thereby assembling a heat exchange structure. The resulting heat exchange structure is incorporated into a shell
9
.
Such a conventional plate type heat exchanger requires three components for constituting the heat exchange element
2
, and thus involves problems that manufacture and management of the components are burdensome and costly.
FIG. 17
is an exploded perspective view of a plate type heat exchanger in which a plurality of heat exchange elements
2
are piled on each other and housed within a shell
9
.
With a plate type heat exchanger having a structure shown in
FIG. 17
, when the number of the heat exchange elements
2
is increased, heat exchange capacity can be improved. Further, a liquid having a large specific volume, such as a vapor or a vapor-liquid two phase fluid, can be used as an external fluid. In
FIG. 17
, the reference numeral
3
denotes an opening portion constituting an introduction passage for an external fluid, the reference numeral
4
an opening portion constituting a discharge passage for the external fluid, the reference numeral
5
an opening portion constituting an introduction passage (supply passage) for an internal fluid, the reference numeral
6
an opening portion constituting a discharge passage (supply passage) for the internal fluid, and the reference numeral
7
a cylindrical communicating portion.
It has been known that when the plate type heat exchanger having the structure shown in
FIG. 17
is used in an absorber or an evaporator of an absorption refrigerating machine, for example, the refrigerating machine can be downsized.
In these heat exchangers, since an internal fluid is generally supplied to a plurality of plates, as shown in
FIG. 17
, the heat exchanger is used in such a state that an inlet and outlet of the heat exchanger and an inlet and outlet (ports) of the plates are connected to each other, and the ports of the plates are connected to each other, via supply passages such as supply pipes, discharge pipes, and communication pipes for a working fluid. In many cases, the supply passages are provided on heat transfer surfaces of the plates because of productivity in such a manner that the supply passages are faced to and communicate with each other when the plates are piled on each other.
In this case, when the flow rate of the internal fluid is increased, it is necessary to thicken the supply passages
5
,
6
. Therefore, the supply passages provided on the heat transfer surfaces occupy the heat transfer area, and simultaneously prevent a flow of the external fluid.
Particularly, as shown in
FIG. 18
, in such cases where the external fluid flows as a liquid film for performing heat exchange, as an absorber or an evaporator in an absorption refrigerating machine, if wide supply passages are provided, then it is difficult to supply the fluid to entire regions below the supply passages and hence the regions are not effectively used as the heat transfer surface in many cases. In
FIG. 18
, a hatched area represents regions of the flow of the fluid, and portions a below the supply passage
5
,
6
without hatching represent regions of no fluid flowing.
Generally, in the plates, there is provided a fluid distribution portion having radial passages for uniformly distributing the fluid supplied from the ports to the plates. As the supply passage becomes wider, the fluid distribution portion becomes more complicated and larger, so that the fluid distribution portion occupys a larger area of the heat transfer surface.
Even if supply passages having an elliptic or rectangular shape are used to solve the above drawbacks, such supply passages increase cost and make productivity worse. Besides, a flow in a direction of the minor axis of the shape of the supply passage is worsened, although a flow in a direction of the major axis can be improved. This is not a solution to the problems.
DISCLOSURE OF INVENTION
The present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a plate type heat exchanger having a highly efficient function of heat exchange, which requires a small number of components and can reduce cost of production and assembly.
It is another object of the present invention to provide a plate type heat exchanger having a highly efficient function of heat exchange, which can be manufactured by a small man-hour and is likely not to prevent a flow of a working fluid even at a high flow rate.
To attain the above objects, according to a first aspect of the present invention, there is provided a plate type heat exchanger having a heat exchange element composed of two plates for exchanging heat between a fluid flowing inside the heat exchan
Inoue Naoyuki
Irie Tomoyoshi
Matsubara Toshio
Suzuki Akiyoshi
Uchimura Tomoyuki
Ebara Corporation
Flanigan Allen
Westerman Hattori Daniels & Adrian LLP
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