Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVEMENTS IN OR RELATING TO FLUID HANDLING APPARATUS
_
Field of the Invention
This invention is concerned with improvements in or
relating to fluid handling apparatus, such as heat exchanger
apparatus and fluid reactor apparatus.
Review of the Prior Art
It is of course a constant aim in all fields of
manufacture to lower costs both of the apparatus itself and of
its cost of operation and maintenance. In the case of heat
exchange apparatus there is therefore a constant endeavour to
improve efficiency, so that the cost of operation is reduced
directly and so that the apparatus is smaller in size, which in
itself is usually a desirable characteristic, such size
reduction resulting in a requirement for less material in its
fabrication. This reduction in material requirement is
especially important in apparatus employed with corrosive fluids
and in difficult environments when expensive corrosion-resistant
materials must be used. It is also an endeavour to provide as
great a freedom as possible from fouling, together with ease of
assembly and disassembly, so as to give accompanying consequent
economy in maintenance. There are similar advantages to be
obtained in the case of fluid reaction apparatus, resulting from
increases in efficiency of the fluid mixing and efficiency of
contact with catalytic material, and also in the case of fluid
reaction apparatus that has heat exchange capability to take
account of the exothermic or endothermic nature of the reactions
involved.
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An improved heat exchange process and apparatus are
disclosed in my European Patent Application Serial No.
81104809.9 (Publication No. 0 042 613) published 30th December
1981. In this process and apparatus the fluid flow takes the
form of a non-turbulent boundary layer or layers immediately
adjacent to the heat transfer surface and a non-turbulent core
layer interfacing with the boundary layer or layers. An
interrupter structure is provided within the flow passage to
interrupt in as non-turbulent a manner as possible the said
boundary layer or layers at a plurality of spaced interruption
spots, whereby parts of the interrupted boundary layer separate
from the heat transfer surface and mix with the core layer to
effect heat transfer between the surface and the core layer.
This structure consists of densely-packed convex sphere segments
each arranged with a part of its convex surface touching or
almost touching the heat transfer surface. Such a structure
provides a very high coefficient of heat transfer without a
disproportionate increase in the pumping power required to move
the fluid through the apparatus,
Definition of the Invention
It is an object of the invention to provide a new fluid
boundary layer interrupter structure for fluid handling
apparatus.
In accordance with the present invention there is
provided in a fluid handling apparatus an interrupter structure
; adapted for pointwise interruption of the boundary layer of a
fluid flow at an apparatus surface or surfaces of the apparatus
immediately adjacent to the interrupter structure, the said
structure comprising:
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a multiplicity of interrupter elements disposed
longitudinally relative to one another in the direction of f low
of the fluid,
each interrupter element comprising a common core and
at least three blade-like members extending mutually outwardly
from the common core so as to separately touch or nearly touch
the said apparatus surface or surfaces adjacent to the
respective element, each blade-like member being of at least
approximately spherical segment profile in side elevation so
that the portion thereof most closely adjacent to the respective
apparatus surface protrudes in~o the said fluid flow boundary
layer for effective pointwise interruption in a zone thereof;
each element thereby providing a number of adjacent
pointwise boundary layer interruption zones corresponding to the
number of blade-like members thereof.
Also in accordance with the invention there is provided
in a fluid handling apparatus an interrupter structure adapted
~or pointwise interruption of the boundary layer of a fluid flow
over a surface or surfaces of the apparatus immediately adjacent
to the structure, the structure coMprising:
a multiplicity of closely spaced interrupter elements
extending longitudinally relative to one another in the
direction of the said fluid flow;
2S each interrupter element comprising a common core of
small dia~eter relative to the overall diameter of the
respective element and from three to ten blade-like members
extending radially outwards from the common core, so as to
separately touch or nearly touch the said apparatus surface or
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surfaces adjacent to the respective element;
each blade-like member being of at least approximately
spherical segment profile in side elevation, so that the portion
thereof most closely ad~acent to the respective apparatus
surface protrudes into the fluid flow boundary layer for
corresponding pointwise interruption in a zone thereof;
each element thereby providing a number of adjacent
pointwise boundary layer interruption zones corresponding to the
number of blade-like members thereof.
Also in accordance with the invention there is provided
in a fluid handling apparatus an interrupter structure providing
multiple interruptions of the ~oundary layer of a fluid flow
over a surface or surfaces of the apparatus immediately adjacent
to the structure, the structure comprising:
a multiplicity of individual interrupter elements
disposed sequentially at predetermined distances so as not to be
contiguous and extending longitudinally relative to one another
in the direction of the said fluid flow;
each interrupter element comprising a common core of
small diameter relative to the overall diameter of the
respective element and at least three elongated blade-like
members extending outwards from the common core, so as to
separately touch or nearly touch the said apparatus surface or
surfaces adjacent to the respective element
each blade-like member in side elevation being radially
; outwardly tapered to a tip which touches or nearly touches the
respective surface, and so that the tip protrudes into the
respective zone of the fluid flow boundary layer for
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corresponding interruption thereof.
Also in accordance with the invention there is provided
in a fluid handling apparatus an interrupter structure providing
multiple interruptions of the boundary layer of a fluid flow
over a surface or surfaces of the apparatus immediately adjacent
to the structure, the structure comprising:
a multiplicity of individual interrupter elements
disposed sequentially at predetermined distances so as not to be
contiguous and extending longitudinally relative to one another
in the direction of the said fluid flow;
each interrupter element comprising a common core of
small diameter relative to the overall diameter of the
respective element and at least three elongated blade-like
members extending outwards from the common core, so as to
separately touch or nearly touch the said apparatus surface or
surfaces adjacent to the respective element
each blade-like member in side elevation being radially
outwardly tapered to a tip which touches or nearly touches the
respective surface, and so that the tip protrudes into the
respective æone of the fluid flow boundary layer for
corresponding interruption thereof;
each element thereby providing a number of adjacent
boundary layer interruptions in respective zones of the boundary
layer corresponding to the number of blade-like members thereof;
the said multiplicity of successive elements providing
within each element between the blade-like members a volume of
increased fluid velocity and between immediately successive
elements a volume of decreased fluid velocity so as to provide a
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correspondin~ multiplicity of changes in fluid velocity,
the said multiplicity of successive elements each
providing greater friction drag adjacent to its core than to its
tip portion such as to produce a corresponding multiplicity of
changes in fluid flow direction through the structure,
the said multiplicity of successive changes in fluid
velocity and flow direction promoting fluid mixing between the
separated fluid boundary layer and the corresponding fluid core.
Also in accordance with the invention there is provided
an interrupter structure for use in a fluid handling apparatus
and adapted for pointwise interruption of the boundary layer of
a fluid flow at an apparatus surface or surfaces of the
apparatus immediately adjacent to the interrupter structure, the
said structure comprising:
a multiplicity of interrupter elements disposed
longitudinally relative to one another,
each interrupter element comprising a common core and
at least three blade-like members extending mutually outwardly
from the common core so as to be able to separately touch or
nearly touch the said apparatus surface or surfaces adjacent to
the respective element, each blade-like member being of at least
approximately spherical segment profile in side elevation so
that the portion thereof most closely adjacent to the respective
ap~aratus surface will protrude into the said fluid flow
boundary layer for effective pointwise interruption in a zone
thereof;
each element thereby providing a number of adjacent
pointwise boundary layer interruption zones corresponding to the
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number of blade-like members thereof.
Also in accordance with the invention there is provided
an interrupter structure for use in a fluid handling apparatus
and adapted for pointwise interruption of the boundary layer of
a fluid flow over a surface or surfaces of the apparatus
immediately adjacent to the structure, the structure comprising:
a multiplicity of closely spaced interrupter elements
extending longitudinally relative to one another;
each interrupter element comprising a common core of
small diameter relative to the overall diameter of the
respective element and from three to ten blade-like members
extending radially outwards from the common core, so as to be
able to separately touch or nearly touch the said apparatus
surface or surfaces adjacent to the respective element;
lS each blade-like member being of at least approximately
spherical segment profile in side elevation, so that the portion
thereof most closely adjacent to the respective apparatus
¦ surface will protrude into the fluid flow boundary layer for
corresponding pointwise interruption in a zone thereof;
each element thereby providing a number of adjacent
pointwise boundary layer interruption zones corresponding to the
number of blade-like members thereof.
Also in accordance with the invention there is provided
an interrupter structure for use in a fluid handling apparatus
and providing multiple interruptions of the boundary layer of a
fluid flow over a surface or surfaces of the apparatus
immediately adjacent to the structure, the structure comprising:
a multiplicity of individual interrupter elements
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disposed sequentially at predetermined distances so as not to be
contiguous and extending longitudinally relative to one another;
each interrupter element comprising a common core of
small diameter relative to the overall diameter of the
respective element and at least three elongated blade-like
members extending outwards from the common core, s~ as to be
able to separately touch or nearly touch the said apparatus
surface or surfaces adjacent to the respective element
each blade-like member in side elevation being radially
outwardly tapered to a tip which will touch or nearly touch the
respective surface, and so that the tip will protrude into the
respective zone of the fluid flow boundary layer for
corresponding interruption thereof.
Also in accordance with the invention there is provided
an interrupter structure for use in a fluid handling apparatus
and providing multiple interruptions of the boundary layer of a
fluid flow over a surface or surfaces of the apparatus
immediately adjacent to the structure, the structure comprising:
a multiplicity of individual interrupter elements
disposed sequentially at predetermined distances so as not to be
contiguous and extending longitudinally relative to one another
in the direction of the said fluid flow;
each interrupter element comprising a common core of
small diameter relative to the overall diameter of the
~5 respective element and at least three elongated blade-like
members extending outwards from the common core, so as to be
able to separately touch or nearly touch the said apparatus
surface or surfaces adjacent to the respective element
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each blade-like member in side elevation being radially
outwardly tapered to a tip which will touch or nearly touch the
respective surface, and so that the tip will protrude into the
respective zone of the fluid flow boundary layer for
S corresponding interruption thereof;
each element thereby providing a number of adjacent
boundary layer interruptions in respective zones of the boundary
layer corresponding to the number of blade-like members thereof;
the said multiplicity of successive elements providing
within each element between the blade-like members a volume of
increased fluid velocity and between immediately successive
elements a volume of decreased fluid velocity so as to provide a
corresponding multiplicity of changes in fluid velocity in fluid
passing therethrough,
the said multiplicity of successive elements each
providing greater friction drag adjacent to its core than to its
tip portion such as to produce a corresponding multiplicity of
changes in fluid flow direction through the structure,
the said multiplicity of successive changes in fluid
velocity and flow direction promoting fluid mixing between the
separated fluid boundary layer and the corresponding fluid core.
Also preferably the spacing between immediately
successive interrupter elements is such as to produce wake
interference flow in the fluid.
The fluid handling apparatus may comprise heat exchange
apparatus in which the interrupter elements are disposed
adjacent the surface of a wall through which heat exchange takes
place.
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The fluid handling apparatus may comprise a fluid
reactor in which the interrupter structure is coated with a
material exhibiting reactive and/or catalytic properties toward
the fluid.
Description of the Drawinqs
Fluid handling apparatus constituting preferred
embodiments of the invention will now be described, by way of
example, with reference to the accompanying diagrammatic
drawings, wherein:
FIGURE 1 is a longitudinal section through a heat
exchanger embodying the invention, taken on the line 1-1 of
Figure 2, parts only of some of the tube thereof being shown
broken away and parts of structures being shown in phantom to
avoid excessive detail;
FIGURE 2 is a part transverse section through the
apparatus of Figure 1, taken on the line 2-2 of Figure 1, only
the lower right quadrant being shown in full to avoid excessive
detail;
FIGURE 3 is a transverse cross-section to an enlarged
scale of an interrupter element of the apparatus of Figures 1
and 2;
FIGURES 4a, 4b and 4c are respective side elevations to
an enlarged scale, and showing interrupter elements of different
profiles;
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FIGURE 5 is a longitudinal cross-section through a
single tube illu~trating the fluid flow therethrough past an
interrupter element; and
FIGURE 6 is a plot of ranking of different heat
s exchanger surfaces, including a surface/structure combination of
the invention.
DescriPtion of the Preferred Embodiments
The heat exchanger of Figures 1 and 2 is of
shell-and-tube type comprising a central shell member lO having
inlet 12 and outlet 14 for the fluid that is to pass in the
shell around the outside of the tubes. The two ends of the
shell member 10 are closed by two respective tube sheet
assemblies, each consisting of two spaced tube sheets 16 and 18
through which pass the ends of a plurality of parallel tubes 20
so as to be supported by the tube sheets. The joints between
the tubes and the apertures in the tube sheets through which
they pass, and also the joints between the tube sheet assemblies
and the adjacent shell members, are sealed by specially shaped
unitary gaskets 22 and 24. Any of the two fluids that leak
through the gaskets enters the space between the tube sheets and
can be vented to atmosphere without cross-contamination of the
fluids.
Two subsidiary like end members 26 and 28 are mounted
on the respective ends of the central shell member 10 abutting
the respective tube sheet assemblies to form respective plenums
for the fluid that enters and discharges from the interiors of
the tubes 20, and are provided respectively with inlet 30 and
outlet 32 for such fluid. The ends of the shell end members 26
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and 28 are closed by respective end plates 34 held to the
members by respective encircling removable split rings 36 and
tensioned band clamps 38. The tube sheet assemblies and the
subsidiary members are held assembled with the central shell 10
in similar manner by means of encircling split rings 40 and
tensioned band clamps 42, the split rings having radially
inwardly extending projections that engage in respective
circumferenctial grooves in the shell members.
Each tube 20 has mounted therein a respective fluid
flow interrupter structure 44 of the invention comprising a
multiplicity of longitudinally spaced interrupter elements 46,
which in this embodiment are mounted longitudinally spaced from
one another along the length of the tube on an elongated axial
core element rod 48 of small diameter relative to the overall
diameter of the elements. The ends of this rod are free of the
interrupter elements and extend out of the tubes 20 through the
reæpective plenums into contact with the adjacent faces of the
removable end plates 34, so that the interrupter structures are
maintained in fixed longitudinal positions in the tubes.
As is seen most clearly in Figures 2 and 3, each
interrupter element 46 consists of a plurality of equal length
blade like members 50 extending mutually radially outwards from
the core rod 48 until they touch, or at least almost touch, the
inside cylindrical wall of the respective tube. As is seen most
clearly in Figures 1, 4, and 5 each blade like member is of
convex curvilinear profile as seen in side elevation, so that it
has only effectively a point 52 of its circumference in contact
with the tube inner wall, or immediately adjacent thereto.
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It is known to those skilled in the art that a fluid
flowing within a passage, such as a tube 20, has a very thin
virtually stationary boundary layer at the tube inner wall which
insulates the wall surface from the main body of the fluid
flowing in a core layer int4rfacing with the boundary layer, the
boundary layer therefore reducing the heat transfer between the
tube inner surface and the core layer. It is also known that an
unobstructed boundary layer increases progressively in thickness
in the direction of fluid flow, which will increase its
insulating effect. Proposals have therefore been made hitherto
to disrupt such boundary layers by roughening or ridging the
surfaces over which they flow, but such proposals have the
effect of also increasing to a disp~oportionately greater extent
the pumping power re~uired to move the fluid through the passage
because of the turbulence that is generataed in the fluid.
In apparatus of the invention the boundary layer at the
tube inner faces is interrupted in a ~spot-wise~ manner at
circumferentially and longitudinally spaced spots by means of
the fluid flow interrupter structure of the invention, while
maintaining a non-turbulent fluid flow in the main body of the
fluid constituted by the core layer. In tbe apparatus of the
invention not only are the heat transfer surfaces not roughened,
etc., but on the contrary they are made as smooth as is
economically possible, to the extent that in some embodiments
both the inner and the outer surfaces of the tubes 20 may be
polished to the desired degree of smoothness. It will be seen
that the blade-like members of each element intercept the
boundary layer at a number of circumferentially-spaced spots
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surrounding the element corresponding to the number of members,
and this occurs for each element of the structure along its
length. The disruption of the boundary layer at the multitude
of longitudinally and circumferentially spaced spots ensures
that it stays thin, while the manner of its disruption ensures
that turbulence is avoided that would cause unduly high friction
drag.
It will be noted that the blade-like members of the
interrupter elements are relatively thick at their root
connections with the axial core rod and taper smoothly and
progressively radially outwa~ds until they terminate in a thin
but smoothly rounded tip at or very closely adjacent to the tube
inner surface. It will be understood by those skilled in the
art that, because of usual manufacturing tolerances in the
manufacture of the tubes and the interrupter structures, and
also because of the need to be able easily to insert the
structures into and remove them from the tubes, there may not
always be positive contact at a particular interruption spot
between the blade member and the tube interior wall, but the
required effect will be obtained as long as the blade edge
intrudes into the boundary layer. In a typical example of a
small heat exchanger e.g. of capacity 20 litres/minute, and in
which the tubes are of 1.25 cm internal diameter the tolerance
required in the manufacture of the tube and interrupter
structure is 0.5 mm to 1.0 mm, which is readily realisable.
At the radially inner part of each interrupter element,
i.e. where the roots of the blades meet the core rod, there is a
maximum of the ratio of blade surface area relative to the path
cross-sectional area for fluid flow through the element, so that
the friction drag is at a maximum. On the other hand, at the
radially outer parts of the element blades the amount of blade
material has become substantially zero, so that the friction
drag is reduced in relation to the crcss sectional area.
Because of these differentials in friction and cross sectional
area a change of momentum is produced in the fluid as it passes
through the element that induces the development of smooth, non
turbulent vortices producing rapid and effective mixing of the
separated boundary layer and its adjacent core layer for
increase in heat exchange efficiency. There is also highly
effective contact of the fluid with the surface of the
interrupter element and with any material such as a catalytic
material thereon. The fluid in these momentum induced vortices
moves from element to element longitudinally of the structure,
and the spacing between the elements can be made such that what
is known as wake interference flow is established by the
coincidence between a vortex upstream of an interruption point
with a vortex downstream of a subsequent interruption point;
such wake interference flow is believed to provide the highest
mixing and heat transfer efficiency with lowest required pumping
power.
Another of the results of this particular blade
configuration is that the fluid flow is predominantly in the
radially outer portion of the tube interior with increased fluid
velocities particularly at the tube inner wall surface. This
type of flow has a number of beneficial effects on the heat
transfer efficiency, in that the rate of heat transfer is
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fundamentally increased because of the rapid flow past the heat
transfer surface, while the boundary layer is kept thin and more
easily disrupted by the shearing effect of the high velocity
fluid.
The general direction of flow of the fluid in a tube is
indicated in Figure 5 by arrows 54 and it will be seen that the
flow interrupter structure causes the production of flow eddies
of shape and rotational frequency that, as described above,
depend upon the ~eometry of the structure. Wake eddies will be
produced around the spots 52 of interruption downstream of the
flow, while advance eddies will be produced upstream of the
flow. If the spacing of the interruption spots 52 is made such
that the advance and wake eddies of immediately successive spots
coincide, then the desired wake interference flow is obtained
with its very efficient non turbulent mixing between the
interrupted boundary layers and the adjacent core layer. A
turbulent flow may be distinguished from a vortex or eddy in
that the former is irregular and there is no observable pattern
as with a vortex. Vortices, eddies and swirls therefore do not
constitute turbulence. The conditions for maintenance of non
turbulent flow with a particular structure can be observed for
example by providing suitable windows in an experimental
structure and adding visible fluids to the fluid flow if
required.
The interrupter structure may readily be produced
relatively inexpensively as a cast or moulded integral element
of required diame~er, element spacing and element free end
length. A variety of different materials can be used, such as
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metals, non-metallic materials such as plastics materials, and
refractory materials such as alumina and cements. Because of
its relatively large surface area and its efficient surface
contact with the mixing flowing fluid the interruption structure
is particularly suited as a support for material with which the
fluid is to be contacted, such as a catalytic material. In
other embodiments comprising reactor apparatus the interrupter
structure itself can be made of the contact and/or catalytic
material, and alumina is a specific example of such a material
10 having this dual property.
The nu~ber of the blade l~ke members to be provided
with each interrupter element is a matter of design for each
heat exchanger. A practical minimum is three, while for small
exchangers (e.g. using tubes of 1.25 cm and less) more than ten
15 would usually result in too great a loss of flow capacity.
Figure 4a shows in side elevation part of a structure
in which the profile of the element is spherical; the profile
is of course a circle. Other profiles can be used and should be
such as to present smoothly contoured edges to the fluid flow,
20 so as to reduce friction losses to a minimum and also to ensure
the maintenance of non turbulent flow. Figure 4b shows for
example elements of an ellipsoidal profile, while Figure 4c
shows elements of an egg or drop shaped profile.; in the latter
two profiles the edge of largest radius faces upstream.
Special situations arise for example when the fluid is
very viscous, such as a viscous oil that is to be heated. Such
a fluid is usually of low thermal conductivity and a thermal
boundary layer will be established immediately adjacent ~o the
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heat transfer surface that is much thinner than the flow
boundary layer. The interrupting structure must be arranged to
interrupt this thinner thermal boundary layer irrespective of
the thickness of the flow boundary layer. The principal factor
in the determination of the thickness of the thermal boundary
layer is the Prandtl number, which is high when the viscosity is
high and the thermal conductivity is low.
One of the principal parameters to be considered in
determining whether a particular fluid flow will be non
turbulent is the Reynolds number which is obtained by the
relation:
R = Fluid Maæs Velocity x Passage_Equivalent Diameter
Classically it was believed that with a Reynolds number
less than about 4,000 the flow must be non turbulent, while if
it was greater than about 6,00G it would become turbulent. An
indication that the flow will be non-turbulent is to plot a
fri~tion-factor curve, beginning at low Reynolds numbers, say
R=100, which will show an abrupt change in slope at the onset of
turbulence. The existence of a friction-factor curve of
constant slope can therefore be an indication that essentially
non-turbulent flow is occuring.
The evaluation of the performance of heat exchanger
surfaces is a difficult subject because of the large number of
¦ variables involved, but one method that has gained acceptance is
described in the Transactions of the Society of Mechanical
Engineers, Vol. 100, August 1978 in a paper by J.G. Soland,
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W.M. Mack, Jr. and W.M. Rohsenow entitled ~Performance Ranking
of Plate-Fin Heat Exchanger Surfaces~. This method involves the
plotting of the number of heat transfer units (NTU) per unit
volume of the heat exchanger core (V), against the pumping power
(E) required to move the fluid through the core per unit volume
of the heat exchanger core (V).
Figure 7 is a plot of the ranking of surfaces in
accordance with this method, comparing surfaces provided with an
interrupter structure of the invention with a surface
constituted by a tube of 1.2 cm diameter and a plate heat
exchanger of 0.5 cm plate pitch. Thus the vertical plot
indicates the number of heat transfer units (NTU) per unit
volume of the heat exchanger core (V), while the horizontal plot
indicates the pumping power (E) required to move the fluid
through the core per unit volume of the heat exchanger core (V).
The test fluid was water and the lowest line A is for
heat transfer in a plain tube of 1.2 cm diameter, using data
obtained from the above-mentioned paper of Soland, Mack and
Rohsenow. The line B is for an ~APV~ plate heat exchanger of
0.5 cm plate pitch, using data obtained from the ~APV Heat
Transfer Handbook, 2nd Edition, published by APV Inc. of
Tonawanda, New York, U.S.A.~. ~t will be seen that line B
represents an improvement of 28% in performance over line A. A
lower line C plots the performance of a shell and tube heat
exchanger of the invention employing seven tubes of 1.25 cm
diameter and equipped internally with radially bladed
interrupter structures and externally with sphere rods on the
shell side with a sphere diameter of 1 cm. The higher line D
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plots the maximum performance so far obtained with a heat
exchanger of the invention. It will be seen that line C
represents an improvement of respectively 250~ and 200g of lines
A and B, while line D represents an improvement of respectively
515% and 400~.
The embodiment of Figures 1 to 3 employs a different
form of interrupter structure in the fluid path constituted by
the space between the shell interior and the tube exteriors,
although the above described bladed structure can of course be
used. This different structure also consists of a core rod 54,
but the longitudinally spaced interrupter elements consist of
solid spheres 56 mounted on the rod at the spacing required to
provide wake interference fluid flow. These sphere carrying
rods, for convenience called sphere rods, are disposed around
the tube exteriors with their longitudinal axes parallel to the
tube axes and with their spherical surfaces in psint contact
with the adjacent tube surfaces; at some locations the spheres
may also touch one another. The spheres have the same effect of
point interruption of the boundary layers and production of
mixing vortices that increase the heat transfer from the
exterior tube surfaces to the fluid. It will be noted that the
ends of the sphere rod cores are free of spheres and are in end
engagement with the tube sheets 16, so that they can be located
accurately longitudinally by changing the length of the sphere
free ends the spheres of one rod can therefore be arranged to be
opposite to the spaces between the spheres on the lmmediately
adjacent rods to ensure the maximum fluid flow capacity in the
path, and minimize the pressure drop of the fluid through the
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shell. The rod ends are also made free of spheres to provide
fluid flow plenum spaces of adequate flow capacity in the shell
adjacent the inlet and outlet to the shell. The radially outer
sides of the radially outermost sphere rods are surrounded by a
f iller material 58 to block the non heat exchanging flow of
fluid that would otherwise take place between the inner wall of
the shell and the adjacent outer parts of the tube walls.
It will be seen that the entire heat exchanger is
readily disassembled by removal of the encircling band clamps 38
and 42 and split rings 36 and 40, when the tube sheet assemblies
can be removed and the interrupter assemblies of both types slid
out from inside and between the tubes for replacement or
cleaning, as may be required. It will be seen that this
disassembly and subsequent reassembly can be effected extremely
lS rapidly by unskilled labour using simple tools. The resulting
separate parts can easily be cleaned with simple apparatus.
. .
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