U.S. patent application number 15/392523 was filed with the patent office on 2018-06-28 for modular shell-and-tube heat exchanger apparatuses and molds and methods for forming such apparatuses.
The applicant listed for this patent is X Development LLC. Invention is credited to Raj Apte, Philippe Larochelle, Martin Schubert.
Application Number | 20180180363 15/392523 |
Document ID | / |
Family ID | 62629590 |
Filed Date | 2018-06-28 |
United States Patent
Application |
20180180363 |
Kind Code |
A1 |
Apte; Raj ; et al. |
June 28, 2018 |
Modular Shell-and-Tube Heat Exchanger Apparatuses and Molds and
Methods for Forming Such Apparatuses
Abstract
Modular tubing apparatuses for use in a shell-and-tube heat
exchanger are described. Multiple apparatuses may be connected in
series to form a high density, small tube diameter, long length
tube apparatus assembly. Casting molds for forming modular tubing
apparatuses are likewise described, including methods for casting
such apparatuses.
Inventors: |
Apte; Raj; (Mountain View,
CA) ; Larochelle; Philippe; (Mountain View, CA)
; Schubert; Martin; (Mountain View, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
X Development LLC |
Mountain View |
CA |
US |
|
|
Family ID: |
62629590 |
Appl. No.: |
15/392523 |
Filed: |
December 28, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22C 9/068 20130101;
F28D 7/16 20130101; F28F 21/081 20130101; F28F 2255/14 20130101;
B22C 9/064 20130101; B22C 9/02 20130101; B22C 9/06 20130101; F28F
9/182 20130101; B22C 9/24 20130101; B22D 25/02 20130101; F28F 9/18
20130101; F28F 9/04 20130101; F28F 2275/04 20130101; F28F 9/0131
20130101; F28F 21/083 20130101; F28D 7/103 20130101 |
International
Class: |
F28F 9/18 20060101
F28F009/18; F28F 9/04 20060101 F28F009/04; F28F 9/013 20060101
F28F009/013 |
Claims
1. A modular tube apparatus for a heat exchanger, the apparatus
comprising: a connecting plate; a plurality of tubes extending from
a bottom surface of the connecting plate, wherein each tube of the
plurality of tubes comprises a distal open end and a hollow portion
extending from the distal open end to the connecting plate; a
plurality of receiving cups, wherein each receiving cup of the
plurality of receiving cups is recessed into a top surface of the
connecting plate to a depth partially through the connecting plate
and disposed opposite a respective tube of the plurality of tubes,
and wherein each receiving cup of the plurality of receiving cups
defines an internal contour that conforms to an outer contour of
the distal open end of the respective tube of the plurality of
tubes; a first plurality of fluid paths inside the connecting
plate, wherein each fluid path of the first plurality of fluid
paths extends from each receiving cup of the plurality of receiving
cups to the hollow portion of each respective tube of the plurality
of tubes; and a second plurality of fluid paths through the
connecting plate, wherein each fluid path of the second plurality
of fluid paths extends from the top surface of the connecting plate
to the bottom surface of the connecting plate.
2. The apparatus of claim 1, wherein the apparatus is formed as a
unitary body.
3. The apparatus of claim 2, wherein the unitary body comprises a
cast material.
4. The apparatus of claim 3, wherein the cast material comprises a
metal.
5. The apparatus of claim 1, wherein each tube of the plurality of
tubes is substantially cylindrical.
6. The apparatus of claim 1, wherein proximate to each receiving
cup of the plurality of receiving cups, the connecting plate is
thicker than the depth of the respective receiving cup.
7. The apparatus of claim 1, wherein a surface of the internal
contour of each receiving cup of the plurality of receiving cups is
configured to form a fluid seal with a surface of the outer contour
of the distal open end of the respective tube of the plurality of
tubes.
8. The apparatus of claim 7, wherein the fluid seal is formed with
a brazing material.
9. The apparatus of claim 7, wherein the internal contour is
substantially cylindrical, wherein the surface of the internal
contour is an internal circumferential surface, wherein the outer
contour is substantially cylindrical, wherein the surface of the
outer contour is an outer circumferential surface, and wherein the
internal circumferential surface is configured to form a fluid seal
with the outer circumferential surface.
10. The apparatus of 1, wherein a ratio of a length of each tube of
the plurality of tubes to an outside width of the distal open end
of each tube of the plurality tubes is at least 50:1.
11. The apparatus of 1, wherein a ratio of a length of each tube of
the plurality of tubes to an outside width of the distal open end
of each tube of the plurality tubes is at least 100:1.
12. The apparatus of claim 1, wherein each tube of the plurality of
tubes is parallel to each other tube of the plurality of tubes.
13. The apparatus of claim 1 further comprising a fillet at the
interface between each tube of the plurality of tubes and the
bottom surface of the connecting plate.
14. The apparatus of claim 1 further comprising a chamfer at the
interface between each tube of the plurality of tubes and the
bottom surface of the connecting plate.
15. A mold assembly comprising: a bottom mold portion comprising: a
bottom block comprising a top surface, and a plurality of cavities
in the bottom block extending downwardly from the top surface to a
first depth; a top mold portion comprising: a top plate positioned
opposite and at a first distance from the top surface of the bottom
block, a first plurality of protrusions extending downwardly from
the top plate to a length less than the first distance, wherein
each protrusion of the first plurality of protrusions is disposed
opposite a respective cavity of the plurality of cavities, and
wherein each protrusion of the first plurality of protrusions
defines an outer contour that conforms to an internal contour at a
base of the respective cavity, a plurality of cores extending
downwardly from each protrusion of the first plurality of
protrusions, wherein each core of the plurality of cores is
disposed within and extends to the first depth of the respective
cavity of the plurality of cavities, and a second plurality of
protrusions extending downwardly from the top plate, wherein each
protrusion of the second plurality of protrusions forms a seal at
the top surface of the bottom block; and a middle mold portion
comprising a wall that forms a seal between the top plate and the
bottom block around the periphery of a void space between the top
plate and the bottom block.
16. The mold assembly of claim 15, wherein each cavity of the
plurality of cavities comprises a locating receptacle at the first
depth, wherein each respective core of the plurality of cores
comprises a locating pin at a bottom end of the core; wherein each
locating receptacle and each respective locating pin are configured
to register the bottom end of each core of the plurality of cores
at a fixed position within the respective cavity.
17. The mold assembly of claim 16, wherein the locating receptacle
comprises a cone, and wherein the locating pin comprises a
cone.
18. The mold assembly of claim 15, wherein each cavity of the
plurality of cavities is substantially cylindrical.
19. The mold assembly of claim 15, wherein each core of the
plurality of cores is substantially cylindrical.
20. The mold assembly of claim 15, wherein each core of the
plurality of cores is parallel to each other core of the plurality
of cores.
21. The mold assembly of claim 15, wherein each cavity of the
plurality of cavities in the bottom block comprises a chamfer at
the top surface of the bottom block.
22. The mold assembly of claim 15, wherein each cavity of the
plurality of cavities in the bottom block comprises a convex fillet
at the top surface of the bottom block.
23. The mold assembly of claim 15, wherein a ratio of the first
depth to a bottom width of each cavity of the plurality of cavities
in the bottom block is at least 50:1.
24. The mold assembly of claim 15, wherein a ratio of the first
depth to a bottom width of each cavity of the plurality of cavities
in the bottom block is at least 100:1
25. The mold assembly of claim 15, wherein the middle mold portion
is integral with the top mold portion.
26. The mold assembly of claim 15, wherein the middle mold portion
is integral with the bottom mold portion.
27. A method of forming a modular tube apparatus comprising the
steps of: providing a bottom mold portion, wherein the bottom mold
portion comprises: a bottom block comprising a top surface, and a
plurality of cavities in the bottom block extending downwardly from
the top surface to a first depth; providing a top mold portion,
wherein the top mold portion comprises: a top plate positioned
opposite and at a first distance from the top surface of the bottom
block, a first plurality of protrusions extending downwardly from
the top plate to a length less than the first distance, wherein
each protrusion of the first plurality of protrusions is disposed
opposite a respective cavity of the plurality of cavities, and
wherein each protrusion of the first plurality of protrusions
defines an outer contour that conforms to an internal contour at a
base of the respective cavity, a plurality of cores extending
downwardly from each protrusion of the first plurality of
protrusions, wherein each core of the plurality of cores is
disposed within and extends to the first depth of the respective
cavity of the plurality of cavities, and a second plurality of
protrusions extending downwardly from the top plate, wherein each
protrusion of the second plurality of protrusions forms a seal at
the top surface of the bottom block; providing a middle mold
portion, wherein the middle mold portion comprises: a wall that
forms a seal between the top plate and the bottom block around the
periphery of a void space between the top plate and the bottom
block; coupling the top mold portion, the middle mold portion, and
the bottom mold portion to form a mold chamber; infiltrating the
mold chamber with a molten material; and decoupling and removing
the top mold portion.
Description
BACKGROUND
[0001] Unless otherwise indicated herein, the materials described
in this section are not prior art to the claims in this application
and are not admitted to be prior art by inclusion in this
section.
[0002] High performance heat exchangers that achieve very low
approach temperatures (for example, effectiveness greater than 99%)
and very low pressure drops (for example, less than 5% or 1%
calculated as (change in pressure)/(inlet pressure) across the heat
exchanger) generally require very small diameter (for example, less
than 10 mm) fluid passages with long lengths (for example, 0.5 m or
1 m or greater). Forming a large quantity of fluid passages (for
example, greater than 100,000) with the above noted dimensions and
then assembling enough of them in parallel to achieve large heat
duties, such as might be used on a grid-scale energy generation or
storage system, represents a significant manufacturing
challenge.
[0003] Conventional methods of constructing shell-and-tube heat
exchangers with long length, small diameter tubes have significant
limitations. To form the tubes, mandrel rod drawing or floating
plug drawing is typically used, but there are limitation such as
manufacturing throughput, the need for intermediate tube diameters
for drawing over the mandrel or plug, and additional secondary
operations, such as mandrel reeling (removal). Finally, a dense
array of individual tubes must then be coupled to an input plenum
and output plenum in a time consuming and sometimes low-reliability
assembly process.
SUMMARY
[0004] Disclosed herein are modular tube apparatuses for
shell-and-tube heat exchangers, and molds and methods for forming
the apparatuses.
[0005] Example apparatuses may include a connecting plate, a
plurality of tubes extending from a bottom surface of the
connecting plate, wherein each tube of the plurality of tubes
comprises a distal open end and a hollow portion extending from the
distal open end to the connecting plate, a plurality of receiving
cups, wherein each receiving cup of the plurality of receiving cups
is recessed into a top surface of the connecting plate to a depth
partially through the connecting plate and disposed opposite a
respective tube of the plurality of tubes, and wherein each
receiving cup of the plurality of receiving cups defines an
internal contour that conforms to an outer contour of the distal
open end of the respective tube of the plurality of tubes, a first
plurality of fluid paths inside the connecting plate, wherein each
fluid path of the first plurality of fluid paths extends from each
receiving cup of the plurality of receiving cups to the hollow
portion of each respective tube of the plurality of tubes, and a
second plurality of fluid paths through the connecting plate,
wherein each fluid path of the second plurality of fluid paths
extends from the top surface of the connecting plate to the bottom
surface of the connecting plate.
[0006] Example mold assemblies may include a bottom mold portion
that may include a bottom block comprising a top surface, and a
plurality of cavities in the bottom block extending downwardly from
the top surface to a first depth. Example mold assemblies may
further include a top mold portion that may include a top plate
positioned opposite and at a first distance from the top surface of
the bottom block, a first plurality of protrusions extending
downwardly from the top plate to a length less than the first
distance, wherein each protrusion of the first plurality of
protrusions is disposed opposite a respective cavity of the
plurality of cavities, and wherein each protrusion of the first
plurality of protrusions defines an outer contour that conforms to
an internal contour at a base of the respective cavity, a plurality
of cores extending downwardly from each protrusion of the first
plurality of protrusions, wherein each core of the plurality of
cores is disposed within and extends to the first depth of the
respective cavity of the plurality of cavities, and a second
plurality of protrusions extending downwardly from the top plate,
wherein each protrusion of the second plurality of protrusions
forms a seal at the top surface of the bottom block. Example mold
assemblies may further include a middle mold portion comprising a
wall that forms a seal between the top plate and the bottom block
around the periphery of a void space between the top plate and the
bottom block.
[0007] Example methods of forming a modular tube apparatus may
include the step of providing a bottom mold portion, wherein the
bottom mold portion includes a bottom block including a top surface
and a plurality of cavities in the bottom block extending
downwardly from the top surface to a first depth. Example methods
of forming a modular tube apparatus may further include the step of
providing a top mold portion, wherein the top mold portion
including a top plate positioned opposite and at a first distance
from the top surface of the bottom block, a first plurality of
protrusions extending downwardly from the top plate to a length
less than the first distance, wherein each protrusion of the first
plurality of protrusions is disposed opposite a respective cavity
of the plurality of cavities, and wherein each protrusion of the
first plurality of protrusions defines an outer contour that
conforms to an internal contour at a base of the respective cavity,
a plurality of cores extending downwardly from each protrusion of
the first plurality of protrusions, wherein each core of the
plurality of cores is disposed within and extends to the first
depth of the respective cavity of the plurality of cavities, and a
second plurality of protrusions extending downwardly from the top
plate, wherein each protrusion of the second plurality of
protrusions forms a seal at the top surface of the bottom block.
Example methods of forming a modular tube apparatus may further
include the step of providing a middle mold portion, wherein the
middle mold portion includes a wall that forms a seal between the
top plate and the bottom block around the periphery of a void space
between the top plate and the bottom block. Example methods of
forming a modular tube apparatus may further include the step of
coupling the top mold portion, the middle mold portion, and the
bottom mold portion to form a mold chamber. Example methods of
forming a modular tube apparatus may further include the step of
infiltrating the mold chamber with a molten material. Example
methods of forming a modular tube apparatus may further include the
step of decoupling and removing the top mold portion.
[0008] These as well as other aspects, advantages, and
alternatives, will become apparent to those of ordinary skill in
the art by reading the following detailed description, with
reference where appropriate to the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIGS. 1A and 1B depict, respectively, a bottom perspective
view and a top perspective view of a modular tube apparatus,
according to an example embodiment.
[0010] FIG. 1C depicts a cross-section view of a modular tube
apparatus, according to an example embodiment.
[0011] FIG. 2A depicts a side perspective view of two modular tube
apparatuses, according to an example embodiment, coupled together
in series.
[0012] FIG. 2B depicts a cross-section view of two modular tube
apparatuses, according to an example embodiment, coupled together
in series.
[0013] FIG. 3 depicts a side perspective view of a top mold portion
of a mold assembly, according to an example embodiment.
[0014] FIG. 4 depicts a perspective view of a middle mold portion
and a bottom mold portion of a mold assembly, according to an
example embodiment.
[0015] FIG. 5 depicts a cross-section view of an assembled mold
assembly with a top mold portion, middle mold portion, and bottom
mold portion, according to an example embodiment.
DETAILED DESCRIPTION
[0016] Example methods and systems are described herein. It should
be understood that the words "example" and "exemplary" are used
herein to mean "serving as an example, instance, or illustration."
Any embodiment or feature described herein as "example,"
"exemplary," or "illustrative" is not necessarily to be construed
as preferred or advantageous over other embodiments or features.
More generally, the embodiments described herein are not meant to
be limiting. It will be readily understood that certain aspects of
the disclosed methods systems and can be arranged and combined in a
wide variety of different configurations, all of which are
contemplated herein.
I. Overview
[0017] Example embodiments herein generally relate to modular tube
portions of shell-and-tube heat exchanger apparatuses, and molds
and methods for forming the modular tube portions. In a preferred
embodiment, a modular tube apparatus for use in a shell-and-tube
heat exchanger may include a connecting plate with an arrangement
of receiving cups on one side and small diameter long tubes on the
other side. The modular apparatus may be configured such that
multiple apparatuses may be connected in series with the tubes of
one apparatus mating to the receiving cups of the next apparatus in
series to form a very long tube assembly with a high-density of
small diameter tubes. This beneficially provides a high heat
transfer design within a shell-and-tube heat exchanger. Preferably,
this type of modular apparatus may be formed as a unitary
homogenous body within a casting mold specifically designed to
allow the formation of a connecting plate with integral long small
diameter tubes. The connecting plate may additionally include one
or more through holes to, for example, allow a thermal fluid to
flow through the apparatus and aid heat transfer with a working
fluid flowing through the tubes.
[0018] FIGS. 1A, 1B, 2A, and 2B are generally illustrative of an
embodiment of the modular tube apparatus. FIGS. 3, 4, and 5 are
generally illustrative of an example casting mold.
II. Modular Tube Apparatuses
[0019] FIGS. 1A and 1B depict a modular tube apparatus 100 for a
heat exchanger, according to an example embodiment. Apparatus 100
may include a connecting plate 102 with an arrangement of receiving
cups 106 recessed into a top surface of the apparatus 100.
Respective small-diameter long-length tubes 104 may extend downward
from the bottom surface of the connecting plate 102. These tubes
104 may be arranged in the regular pattern as shown, or in other
regular or irregular patterns. The plate 102 may be flat as
illustrated or may be non-flat. Preferably, the tubes 104 are
arranged in a parallel configuration with each other. As discussed
with respect to FIG. 2A, the bottom (distal) ends of the tubes 104
are configured to fit into and mate with the receiving cups 106,
such that multiple apparatuses 100 may be stacked in series to form
a long tube assembly with a high-density of tubes for use in a heat
exchanger.
[0020] The apparatus 100 is preferably cast as a metal or metal
matrix composite with a unitary body in a permanent mold. Preferred
metals include, as non-limiting examples, stainless steel alloys
Type 304 or Type 316. The unitary body may be a homogenous
casting.
[0021] For purposes of illustrative clarity only, the apparatus 100
is shown with a five-by-five array of tubes 104 for a total of
twenty-five tubes 104. Preferably for a heat exchanger requiring a
high heat load, such as one is configured for use in a grid scale
energy storage system, a modular tube apparatus, such as apparatus
100, may have on the order of approximately 10.sup.1, 10.sup.2,
10.sup.3, 10.sup.4, 10.sup.5 or more tubes per apparatus. The use
of the five-by-five array is for illustration only and embodiments
including up to and beyond 10.sup.5 tubes per apparatus are within
the scope claimed herein.
[0022] In the illustrated embodiment, the tubes 104 are preferably
formed as substantially cylindrical tubes. Because the apparatus
100 is preferably cast as unitary body in a permanent mold, it may
be necessary to include draft on cast parts that must be removed
from the permanent mold, and/or on permanent mold portions that
must be removed from cast parts. Accordingly, and for purposes
herein, the term "substantially cylindrical" should be understood
to mean cylindrical with a 0.degree. or greater draft angle along
an interior and/or exterior surface that may be in contact with a
mold wall surface. For practical purposes, the tubes 104 may have
an approximately 1.5.degree. draft angle on either or both the
exterior surface and the interior hollow portion. Likewise for the
connecting plate 102. However, depending on the mold constraints,
the draft angle may be less than or greater than 1.5.degree. for
various parts. The wall thickness of tubes 104 that are cast may be
constant or varied along the length of the tube by varying the
draft angle between the mold cavity or a respective core.
Additionally, draft angles may be varied along the length of the
tubes 104. For illustrative clarity only, and not as a limitation,
all draft angles are drawn at 0.degree. in the illustrative
Figures.
[0023] Preferably, each of the tubes 104 may be approximately 10 mm
or less in width or diameter at the distal end with a length of 100
mm, 500 mm, 1000 mm to 2000 mm or longer. Both smaller and larger
diameter tubes 104 are considered and both shorter and longer
lengths are considered as well. Length to diameter ratio (or length
to width ratio if non-cylindrical) may be tuned for desired thermal
transfer properties of the heat exchanger, casting shrinkage and
deformation, practical draft angles, or other considerations. For
illustrative clarity only, the tubes 104 in FIGS. 1A, 1B, and 2A
are shown with a shorter length to diameter ratio than the 50:1.
100:1, and 200:1 ratios described above.
[0024] While cylindrical tubes, and matching cylindrical receiving
cups, are preferred shapes of tubes 104 and receiving cups 106 due
to fluid flow characteristics, mating requirements (including
susceptibility to twist), and heat transfer properties, other
shapes are also considered, so long as the distal end of a tube 104
is configured to mate with a receiving cup 106 to form a fluid
seal. Non-limiting examples include square, hexagonal, or octagonal
tubes. The fluid seal may preferably be formed through the use of a
brazing material at one or more mating surfaces of the tubes 104
and receiving cups 106, but other non-limiting examples may include
compression fitting, locking taper with perpendicular compressive
force, welding, gasketing, or other configurations.
[0025] A fillet or chamfer 104a may be included at the interface of
each tube 104 with the bottom surface of the connecting plate 102.
The fillet or chamfer 104a may provide strength at that
stress-prone area and/or may provide structural material below the
receiving cup, as is evident in the cross-sectional view of FIG.
1C.
[0026] While an internal fluid (e.g., a working fluid) may flow
through the apparatus 100 in enclosed paths through receiving cups
106, internal connecting fluid paths 112 (illustrated in FIG. 1C),
and hollow portions 110 of the tubes 104, an external fluid (e.g.,
a thermal fluid) may flow across the tube 104 exteriors. Tubes 104
may include fins or other heat transfer aids along the exterior of
the tubes 104, including straight fins, helical fins, radial fins,
and dimples or protrusions, to aid heat transfer between a working
fluid and a thermal fluid.
[0027] To enhance and/or allow flow of the external fluid, a second
set of fluid paths 108 may extend completely through the connecting
plate 102 from the top surface to the bottom surface. The fluid
paths 108 may be arranged as shown or in other regular or irregular
patterns. Additional or alternatively shaped fluid paths may be
added via a mold or other means to optimize the flow of the thermal
fluid through the plate 102 to optimize the heat transfer. This may
beneficially provide better flow and/or circulation of the external
fluid; and, in an embodiment where a shell is sealed to the
external periphery of the connecting plate 102, the fluid paths 108
provide a means of fluid flow between apparatuses, such as
apparatus 100, connected in series.
[0028] FIG. 1C illustrates a cross-section view of modular
apparatus 100. A break line illustrates that the length 104L of
tubes 104 is preferably much longer than may be practicably
depicted in the illustration. Preferably, the tubes 104 have a
length 104L to outside width 104d ratio of at least 50:1, 100:1, or
200:1.
[0029] In this illustrated embodiment of modular apparatus 100,
where the tubes 104 are illustrated as substantially cylindrical,
the width 104d of the distal open end of each tube 104 may also be
considered the outer diameter of the tube 104. Similarly, where the
receiving cups 106 are also illustrated as substantially
cylindrical, the bottom width 106d of the receiving cup 106 may be
considered the inside diameter of the bottom of the receiving cup
106. In other non-cylindrical embodiments, the widths 104d and 106d
may be considered the widths of respective opposing surfaces. For
example, for a tube 104 and respective receiving cup 106, each with
a regular polygonal contour, the widths 104d and 106d may be
measured as flat-to-flat, vertex-to-vertex, or flat-to-vertex.
[0030] The distal open end of each tube 104 has an outer contour
that conforms to an internal contour of the respective receiving
cup 106. In the illustrated cylindrical embodiment, the outer
contour of the distal open end of tube is substantially cylindrical
with an outer circumferential surface 116. Similarly, the internal
contour of the respective receiving cup 106 is substantially
cylindrical with an internal circumferential surface 114. The
widths 106d and 104d may be sized such that the internal
circumferential surface 114 may form a fluid seal with a mating
outer circumferential surface 116. Brazing may be used to form the
fluid seal, though other configurations are considered, as
described above.
[0031] Alternatively or additionally, the fluid seal may occur at
another surface along the internal and external contours. For
example, the fluid seal may occur at a mating interface between the
bottom surface of the tube 104 and the annular bottom surface of
the receiving cup 106. Again, brazing may be used to form the seal,
though other configurations are considered.
[0032] As shown in FIG. 1C, each of the receiving cups 106 may be
recessed and extend partially through the connecting plate 102 to a
distance less than the connecting plate's thickness 102L at the
receiving cups. Each receiving cup 106 may be connected to a hollow
portion 110 of the respective tube 104 by a fluid path 112 inside
the connecting plate 102. Preferably each fluid path 112 and hollow
portion 110 of the respective tube 104 create a smooth and straight
fluid path from the receiving cup 106 to the distal open end of the
tube 104.
[0033] FIG. 2A illustrates two modular tube apparatuses 100
connected in series, with tubes 104 seated in respective receiving
cups 106. Multiple modular tube apparatuses 100 may accordingly be
connected in series to create a very long tube assembly for use in
a shell-and-tube heat exchanger. Fluid paths 108 may be present and
allow fluid movement not only across the tubes 104 but also through
the connecting plates 102.
[0034] FIG. 2B illustrates a cross-section view of two modular tube
apparatuses 100 connected in series, with tubes 104 seated in
respective receiving cups 106. Break lines illustrate that the
tubes 104 are longer than may be practicably illustrated. In an
embodiment with substantially cylindrical tubes 104, outside
diameter 104d at the distal open end of each tube 104 may be sized
to create a fluid seal against the inside diameter 106d of
receiving cup 106. Braze or other materials may be used to create
the fluid seal. As shown in FIG. 2B, stacking modular tube
apparatuses 100 in series creates a contiguous fluid path through
the tubes 104, allowing for very long fluid paths in small diameter
tubes.
III. Molds for Modular Tube Apparatuses
[0035] FIG. 3 illustrates an example top mold portion 300 of a mold
assembly 500 (see FIG. 5 for further detail) for casting
embodiments of unitary modular tube apparatuses described herein.
Top mold portion 300 may include a top plate 302 with protrusions
306 extending downward from the top plate 302. The protrusions 302
are short and configured to form receiving cups in a modular tube
apparatus for a heat exchanger, such as, for example, the receiving
cups 106 of the modular tube apparatus 100. As depicted, the
protrusions 306 are substantially cylindrical, but may be any shape
as discussed herein with respect to receiving cups.
[0036] Extending downward from the protrusions 306 are cores 304
with a core body 304a. The cores 304 are configured to form the
hollow portions of tubes in a modular tube apparatus for a heat
exchanger, such as, for example, the hollow portions 110 of tubes
104 in the modular tube apparatus 100, as well as the fluid paths
connecting the receiving cups and tubes, such as fluid paths 112.
As depicted, the cores 304 are substantially cylindrical, but may
be any shape as discussed herein with respect to tubes. Preferably,
the cores 304 are arranged in a parallel configuration with each
other. Each core may further include a locating pin 304b at the
base of the core 304.
[0037] The top mold portion 300 may also include protrusions 308
extending downward from the top plate 302. The protrusions 308 are
configured to form fluid paths through a connecting plate in a
modular tube apparatus for a heat exchanger, such as, for example,
the fluid paths 108 through the connecting plate 102 of the modular
tube apparatus 100. As depicted, the protrusions 308 are
substantially cylindrical, but they may take other forms as
well.
[0038] For purposes of illustrative clarity only, the example mold
portions 300 and 400 illustrated in FIGS. 3, 4, and 5 are shown
with a five-by-five array of cores 304 and receptacles 306 and
matching cavities 404 (see FIG. 4 for further detail), for a total
of twenty-five tube forming mold sections. Preferably for a large
duty heat exchanger, such as one configured for use in a grid scale
energy storage system, the mold for a cast modular tube apparatus
may have on the order of approximately 10.sup.1, 10.sup.2,
10.sup.3, 10.sup.4, 10.sup.5 or more tube forming mold sections per
casting mold. The use of the five-by-five array is for illustration
only and embodiments up to and beyond 10.sup.5 tube forming mold
sections is within the scope of the claims herein.
[0039] FIG. 4 illustrates an example bottom mold portion 400 of a
mold assembly for casting embodiments of unitary modular tube
apparatuses described herein. Bottom mold portion 400 includes a
bottom block 406 and a top surface 402. Extending downward from the
top surface 402 are cavities 404. In conjunction with the top mold
portion 300, the cavities 404 are configured to form tubes in a
modular tube apparatus for a heat exchanger, such as, for example,
the tubes 104 in the modular tube apparatus 100. As depicted, the
cavities 404 are substantially cylindrical, but may be any shape as
discussed herein with respect to tubes. Preferably, the cavities
404 are arranged in a parallel configuration with each other. Each
cavity 404 may further include a locating receptacle 404b at the
bottom of the cavity 404, as illustrated in FIG. 5. Each cavity 404
may have a chamfer 404a, a convex fillet, or other formation
configured to provide strength and/or structural material below a
molded receiving cup.
[0040] FIG. 4 also illustrates an example middle mold portion 450.
Middle mold portion 450 may take the form of a wall that seals
between a component of a top mold portion, for example the top
plate 302 of top mold portion 300, and a component of a bottom mold
portion, for example the top surface 402 of bottom mold portion
400. The middle mold portion 450 may extend around the periphery of
a void space that is used to form a connecting plate, for example
it may extend around the periphery of a void space between a top
plate 102 and a bottom block 406.
[0041] In the example embodiment depicted in FIG. 4 and FIG. 5,
middle mold portion 450 is depicted as a separate mold portion, but
it may also be fixed or unitary with bottom mold portion 400 or
fixed or unitary with top mold portion 300.
[0042] FIG. 5 illustrates an example embodiment of an assembled
mold assembly 500, which may include top mold portion 300, middle
mold portion 450, and bottom mold portion 400. Top plate 302 may be
positioned opposite and at a distance 450L above the top surface of
bottom block 400. The positioning forms a void space 502 which
forms a connecting plate, such as connecting plate 102, where the
distance 450L corresponds to a thickness of the connecting plate,
with accounting for shrinkage and other dimensional considerations
for casting processes. Middle mold portion 450 surrounds the
perimeter and seals the void space 502 for the connecting
plate.
[0043] Within the connecting plate void space 502, protrusions 306
extend downward from the top plate 302 to a depth less than the
distance 450L, so as to form receiving cups in a cast connecting
plate, such as receiving cups 106 in connecting plate 102. The
protrusions 306 are arranged opposite the cavities 404 in the
bottom block 406. The protrusions 306 define an outer contour that
conforms to an internal contour at the base 404c of a respective
cavity 404.
[0044] The cores 304 may extend from the bottom of the protrusions
306 to the bottom of the respective cavities 404, partially
defining void spaces 504 and 506, and forming a fluid path in the
casting from the receiving cups 106, through the connecting plate
102 (e.g., fluid paths 112), and through the tubes 104 (e.g.,
hollow portions 110).
[0045] Each core 304 may include a locating pin 304b that mates
with a locating receptacle 404b at the bottom of the cavity 404 to
register the bottom end of the core 304 at a fixed position within
the cavity. Preferably, the locating pin 304b and locating
receptacle 404b are matching cones, one in positive relief and one
as a cavity. As illustrated, the locating pin 304b in shown in
positive relief and the locating receptacle 404b is shown as a
cavity completely filled by the locating pin 304b.
[0046] As previously described, bottom block 406 may include a
chamfer 404a at each cavity 404 opening at the top surface of the
bottom block. The chamfer 404a partially defines a void space 504
configured to provide strength and/or structural material below the
receiving cup 106 in the cast apparatus.
[0047] Protrusions 308 may also extend downward from top plate 302
all the way through the void space 502 and form a seal with the top
surface 402 of the bottom block 406. In the illustrated embodiment,
the protrusions 308 may extend to and contact a flat top surface
402 of the bottom block 406 to form through-hole fluid paths in a
cast connecting plate, such as fluid paths 108; however, other
configurations are also possible to form through-hole fluid paths
through the connecting plate. For example, top surface 402 may
include slight recesses into which protrusions 308 seat, while
still forming a seal with the top surface 402 around the perimeter
of the protrusions 308.
[0048] Mold assemblies for casting unitary modular tube apparatuses
such as mold assembly 500, are preferably permanent molds, though
portions or sections may be non-permanent (e.g., sand casting). To
the extent that mold assembly 500 includes permanent mold portions,
it may be necessary to include draft on areas that must be
separated from the casting. For practical purposes, draft angles
may be approximately 1.5.degree.. However, depending on the mold
constraints of a particular embodiment, the draft angle may be less
than or greater than 1.5.degree.. Accordingly, and for purposes
herein, the term "substantially cylindrical" should be understood
to mean cylindrical with a 0.degree. or greater draft angle. The
void space 506 width between cores 304 and respective cavities 404
may be constant or varied along the length of the tube by varying
the draft angle of the cavity 404 or core 304. Additionally, draft
angles may be varied along the length of the cavity 404 or core
304.
[0049] Preferably, each of the cavities 404 may have a width or
diameter 404d of approximately 10 mm or smaller in diameter at the
bottom with a length 404L of 100 mm, 500 mm, 1000 mm to 2000 mm or
longer. Both smaller and larger widths/diameters 404d are
considered and both shorter and longer lengths 404L are considered
as well. Length to diameter ratio (or length to width ratio if
non-cylindrical) may be tuned for desired thermal transfer
properties of the heat exchanger, casting shrinkage and
deformation, practical draft angles, or other considerations. For
illustrative clarity only, the cavities 404 and cores 304 in FIGS.
3, 4, and 5 are shown with a shorter length to diameter ratio than
the 50:1. 100:1, and 200:1 ratios described herein. A break line is
used in FIG. 5 to illustrate that the lengths are preferably much
longer than may be practicably depicted in the illustration.
[0050] Cavities 404, cores 304, and matching protrusions 306, are
preferably shaped as substantially cylindrical due to fluid flow
characteristics, mating requirements (including susceptibility to
twist), and heat transfer properties. However, other shapes are
also considered. As long as the distal end of a formed tube may
mate with a formed receiving cup to form a fluid seal, other
configurations are considered, including the non-limiting examples
of square, hexagonal, or octagonal forms.
[0051] In the illustrated embodiment of mold assembly 500, where
the cavities 404 are illustrated as substantially cylindrical, the
width 404d of the bottom end of each cavity 404 may also be
considered the inner diameter of the cavity 404. Similarly, where
the protrusions 306 are also illustrated as substantially
cylindrical, the bottom width 306d of the protrusions 306 may be
considered the outside diameter of the bottom of the protrusions
306. In other non-cylindrical embodiments, the widths 404d and 306d
may be considered the widths of respective opposing surfaces. For
example, regular polygonal contours, the widths 404d and 306d may
be measured as flat-to-flat, vertex-to-vertex, or
flat-to-vertex.
[0052] The mold assembly 500 is preferably constructed as a
reusable permanent mold and of materials sufficient to withstand
repeated high-temperature casting of materials such as metal or
metal matrix composites, including stainless steel alloys Type 304
or Type 316. For example, the mold may be formed as a ceramic mold
using laser-based rapid prototyping, a graphite or graphite/metal
composite mold, or other rapid prototyping formed mold that may
allow the long and thin forms required of the cores and cavities.
For metal casting, and particularly stainless steel casting, the
mold assembly should be capable of withstanding a casting
temperature of approximately 1350.degree. C.
[0053] Various casting methods may be used with the mold assembly
500. For example, centrifugal, spin, vacuum, low-pressure, liquid
metal pumping and high-pressure casting methods may be employed
depending on mold design parameters and desired or acceptable
finish and/or porosity.
[0054] Risers, gates, vents, sprues/ports and runners may be
necessarily and additionally be present in any claimed mold
assembly, including mold assembly 500. Inclusion of some or all of
such casting mold structures is considered, though not shown, and
such casting mold structures may be included in example mold
assembly 500 and other embodiments.
IV. Methods for Casting for Modular Tube Apparatus
[0055] The casting process may be accomplished by providing a mold
assembly according to embodiments described herein, coupling
together the portions of the mold assembly to form a mold chamber,
infiltrating the mold chamber with a molten material, and later
decoupling some or all the mold portions in a manner sufficient to
remove the cast modular tube apparatus.
[0056] As a specific example method to cast an embodiment of the
modular tube apparatus 100 described herein, the following steps
may be accomplished.
[0057] A bottom mold portion may be provided. The bottom mold
portion may include a bottom block with a top surface. A plurality
of cavities in the bottom block may extend downward from the top
surface into the interior of the bottom block.
[0058] A top mold portion may be provided. The top mold portion may
include a top plate positioned opposite and at a first distance
from the top surface of the bottom block. A first plurality of
protrusions may extend downward from the top plate to a length less
than the first distance. Each protrusion of the first plurality may
be disposed opposite a respective cavity of the plurality of
cavities. Each protrusion of the first plurality may define an
outer contour that conforms to an internal contour at a base of the
respective cavity. A plurality of cores may extend downward from
each protrusion of the first plurality. Each core may be disposed
within the respective cavity and form a respective void space in
each cavity. A second plurality of protrusions may extend downward
from the top plate. Each protrusion of the second plurality may
form a seal at the top surface of the bottom block.
[0059] A middle mold portion may be provided. The middle mold
portion may include a wall that forms a seal between the top plate
and the bottom block around the periphery of a void space between
the top plate and the bottom block.
[0060] The top mold portion, middle mold portion, and bottom mold
portion may be coupled together to form a mold chamber. As
non-limiting examples, the portions may be bolted or clamped
together with internal and/or external bolts or clamps.
[0061] The mold chamber may take the negative form of a modular
tube apparatus with or without additional risers, gates, ports, or
structural supports, and the negative form be configured to account
for shrinkage or growth in the casting material. The mold chamber
may be infiltrated with a molten material. Preferably materials
include Type 304 or 316 stainless steel.
[0062] Following a dwell period after infiltration, one more mold
portions mays be decoupled and removed and then the cast modular
tube apparatus removed. In the embodiment illustrated as mold
assembly 500, the top portion 300 with cores 304 may be decoupled
and removed, allowing the modular tube apparatus 100 to be
removed.
V. Conclusion
[0063] The particular arrangements shown in the Figures should not
be viewed as limiting. It should be understood that other
embodiments may include more or less of each element shown in a
given Figure. Further, some of the illustrated elements may be
combined or omitted. Yet further, an exemplary embodiment may
include elements that are not illustrated in the Figures.
[0064] Additionally, while various aspects and embodiments have
been disclosed herein, other aspects and embodiments will be
apparent to those skilled in the art. The various aspects and
embodiments disclosed herein are for purposes of illustration and
are not intended to be limiting, with the true scope and spirit
being indicated by the following claims. Other embodiments may be
utilized, and other changes may be made, without departing from the
spirit or scope of the subject matter presented herein. It will be
readily understood that the aspects of the present disclosure, as
generally described herein, and illustrated in the figures, can be
arranged, substituted, combined, separated, and designed in a wide
variety of different configurations, all of which are contemplated
herein.
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