Heat exchange – Gradated heat transfer structure
Reexamination Certificate
2000-04-14
2001-09-11
Lazarus, Ira S. (Department: 3743)
Heat exchange
Gradated heat transfer structure
C165S166000, C165S167000
Reexamination Certificate
active
06286588
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an evaporator for evaporating a low temperature fluid through a heat transfer from a high temperature fluid to the low temperature fluid, and especially to an evaporator having a high evaporation efficiency.
2. Description of the Related Art
In general, an evaporator is used in a plant of electric generation by temperature difference, steam power, chemistry, food engineering and the like, a refrigerator and a heat pump. Such an evaporator can make heat exchange between high temperature fluid and low temperature fluid for the purposes of making change of phase of the low temperature fluid from a liquid phase to a gaseous phase. The conventional evaporator may be classified into a shell and tube evaporator, a plate type evaporator, a spiral type evaporator and the like. The plate type evaporator is generally used as an evaporator for evaporating the low temperature fluid through the heat of the high temperature fluid for example in a plant of electric generation by temperature difference. An example of the conventional evaporator is shown in
FIGS. 4 and 5
.
FIG. 4
is an exploded perspective view illustrating essential components of the conventional evaporator.
FIG. 5
is a schematic descriptive view of the conventional evaporator in an assembled condition.
The conventional evaporator
100
as shown in
FIGS. 4 and 5
is provided with plural pairs of heat exchange plates
101
,
102
. In each pair, the heat exchange plate
101
is placed on the other heat exchange plate
102
. Upper and lower guide rods
105
,
106
held between a stationary frame
103
and a support rod
104
support the plural pairs of these heat exchange plates
101
,
102
. The plural pairs of the heat exchange plates
101
,
102
are firmly held between the stationary frame
103
and a movable frame
107
that is mounted on the guide rods
105
,
106
. Two heat exchange passages A, B are formed on the opposite surfaces of each of the heat exchange plates
101
,
102
. A high temperature fluid
108
flows in the heat exchange passage A and a low temperature fluid
109
flows in the other heat exchange passage B so as to make heat exchange.
The above-mentioned heat exchange plates
101
,
102
having a prescribed shape and a surface condition can be obtained by press-forming a plate-shaped material. Openings “a”, “b”, “c” and “d” through which the high temperature fluid
108
or the low temperature fluid
109
can pass, are formed at four corners of each of the heat exchange plates
101
,
102
. Packing members
111
,
112
are placed on the surfaces of the heat exchange plates
101
,
102
, respectively, so as to prevent the heat exchanger fluid
108
and the working fluid
109
from flowing in a mixing condition. The heat exchange plates
101
,
102
have the same shape, but the heat exchange plates
102
is placed upside down relative to the normal placement of the heat exchange plate
101
.
The heat exchange plates
101
,
102
serving as the heat transferring face has a pattern of irregularity (not shown) formed thereon in order to increase the heat transferring area and facilitate the heat transfer from the high temperature fluid
108
to the heat transferring face as well as the heat transfer from the heat transferring face to the low temperature fluid
109
.
However, due to the above-described structure of the conventional evaporator, the inlet portion through which the high temperature fluid
108
flows toward a zone between the heat exchange plates
101
,
102
serving as the heat transfer face is small relative to the size of the plates
101
,
102
so that the high temperature fluid
108
, which is supplied through the inlet portion, has a velocity distribution in the width direction of the plates
101
,
102
. As a result, a uniform flowing condition of the supplied high temperature fluid
108
over the entirety of the heat transferring face cannot be obtained, leading to a non-uniform flowing distribution. Accordingly, a uniform contact condition of the high temperature fluid
108
with the heat transferring face over its entirety cannot also be obtained, causing a problem of low heat transfer efficiency of the high temperature fluid to the heat transferring face although the heat transferring face is relatively large.
SUMMARY OF THE INVENTION
An object of the present invention, which was made to solve the above-described problems is therefore to provide an evaporator in which a heat transferring face has a shape by which a high temperature fluid can come into contact with the entirety of the heat transferring face in a uniform state, and a stable and sufficient heat exchange can be made over the entirety of the heat transferring face to facilitate evaporation of the low temperature fluid, thus improving the heat exchange efficiency.
In order to attain the aforementioned object, an evaporator of the present invention comprises:
at least one heat transferring face formed of a plate-shaped material, change of phase of a low temperature fluid from a liquid phase to a gaseous phase being made by causing a high temperature fluid and the low temperature fluid to flow on opposite surface sides of said heat transferring face, respectively, so that flowing directions of said high and low temperature fluids are perpendicular to each other, to make a heat exchange, wherein:
said heat transferring face comprises a plurality of local heat transferring zones, which are arranged in the flowing direction of said low temperature fluid, said local heat transferring zones having prescribed patterns of irregularity, which are different from each other, and each of said prescribed patterns of irregularity being formed by opposite surfaces of said heat transferring face, which have a common concavo-convex shape to each other and an inverse relationship to each other in concavo-convexities that appear on the opposite surfaces of said heat transferring face, which locate on the high and low temperature fluids sides, respectively; and
the concavo-convexity of the pattern of irregularity in each of said local heat transferring zones has a shape, which permits to impart a large resistance force to said high temperature fluid in a place where the high temperature fluid has a high flowing velocity and a small resistance force thereto in another place where the high temperature fluid has a low flowing velocity, and said high temperature fluid can flow along the heat transferring face in a uniform distribution state in each of the local heat transferring zones.
According to the present invention, by providing the local heat transferring zones on the heat transferring face for the heat exchange, forming the prescribed patterns of irregularity, which are different from each other in the respective local heat transferring zones and imparting resistance corresponding to the flowing velocity of the high temperature fluid to the supplied high temperature fluid by the patterns of irregularity in the respective local heat transferring zones, it is possible to distribute uniformly the supplied high temperature fluid to each of the local heat transferring zones of the heat transferring face. According to the present invention, by providing the local heat transferring zones on the heat transferring face for the heat exchange, forming the prescribed patterns of irregularity, which are different from each other in the respective local heat transferring zones and imparting resistance corresponding to the flowing velocity of the high temperature fluid to the supplied high temperature fluid by the patterns of irregularity in the respective local heat transferring zones, it is possible to uniformly distribute the supplied high temperature fluid to each of the local heat transferring zones of the heat transferring face.
There may be adopted, as the occasion demands, a structure that the pattern of irregularity of one of the local heat transferring zones of said heat transferring face, in which the high temperature fluid has a maximum flowing velocity, is
Lazarus Ira S.
McKinnon Terrell
Rader & Fishman & Grauer, PLLC
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