TUBE SHELL HEAT EXCHANGER WITH BAFFLES AND SERPENTINE TUBING

ECHANGEUR DE CHALEUR A SERPENTIN ET CHICANES

English Abstract

Tube and Shell Heat Exchanger with
Baffles and Serpentine Tubing
Abstract
A tube and shell heat exchanger is provided having counter flow
heat transfer. A shell assembly has a series of baffles located
therein. A cover assembly having cover baffles is mounted to the
shell assembly for coacting with the baffles of the shell to
provide a serpentine flow path through the heat exchanger. A
serpentine shaped tube is placed within the heat exchanger such
that the baffles form a counter flow path for fluid flowing within
the shell and the tube forms a fluid flow path for heat transfer
media flowing through the tubes.

Claims

-7-
The embodiments of the invention on which an exclusive property or
privilege is claimed are defined as follows:
1. A heat exchanger for transferring heat energy between the
first fluid and the second fluid which comprises a shell assembly
including a casing forming an open ended enclosure and a plurality
of shell baffles defining a series of zones within the enclosure,
a cover assembly adapted to cover the opening in the casing, said
cover assembly having a series of cover baffles which extend
between the shell baffles dividing each zone of the enclosure into
two regions and having means to supply the second fluid to the
enclosure, and a serpentine shaped tube having the first fluid
flowing therethrough located within the enclosure said tube
extending into each zone of the enclosure and having a portion
thereof located within each region of each zone such that heat
energy may be transferred between the first fluid and the second
fluid.
2. The apparatus as set forth in claim 1 wherein the cover
baffles extending from the cover into the zones of the enclosure
terminate prior to the end of the zone such that there is a space
within the enclosure between the end of the cover baffle and the
casing, and wherein the shell baffles extending from the casing
terminate prior to the cover such that there is a space within the
enclosure between the cover assembly and the end of the shell
baffles.
3. The apparatus as set forth in claim 2 wherein the serpentine
shaped tube comprises hairpin portions each having two legs joined
by a connecting portion extending into each zone of the enclosure,
said hairpin portions having a cover baffle extending between the
legs of the hairpin portions such that one leg of the hairpin
portion is within each region of the zone and wherein the
connecting portion of the hairpin portion is located in the space
between the end of the cover baffle and the casing.

-8-
4. The apparatus as set forth in claim 3 wherein the serpentine
shaped tube further comprises return bend portions connecting
adjacent hairpin portions, the return bend portions being located
between the end of the shell baffles and the cover plate to
connect hairpin portions of the adjacent zones.
5. The apparatus as set forth in claim 4 wherein the first fluid
flows through the tube and the second fluid flows through the
casing in the flow path defined by the cover baffles and shell
baffles, said flow path being the same path defined by the tube.
6. The apparatus as set forth in claim 5 wherein the first fluid
flowing through the tube is connected to flow in an opposite
direction from the second fluid flowing through the casing.
7. A heat exchanger for transferring heat energy between a first
liquid and a second fluid which comprises a shell assembly having
a casing defining an open ended enclosure and a series of shell
baffles dividing the casing into a plurality of zones, said zones
extending from one end of the casing to a termination point spaced
from the open end of the enclosure, a cover assembly for closing
the enclosure by covering the opening with a cover plate, said
assembly having a series of cover baffles extending from the cover
plate, one into each zone of the enclosure, the cover baffles
having a termination point spaced from the end of the casing from
which the shell baffles commence such that the combination of
baffles provides a serpentine flow path through the enclosure,
said cover assembly further including means for supplying fluid to
the fluid flow path of the enclosure; and a tube assembly in a
serpentine configuration mounted within the flow path of the
enclosure such that heat energy may be transferred between the
fluid flowing through the tube and liquid flowing along the flow
path.

-9-
8. The apparatus as set forth in claim 7 wherein the shell
baffles are spaced from each other and are located in planes
substantially parallel with each other, wherein the cover baffles
are spaced from each other and located in planes substantially
parallel with the planes of the shell baffles and wherein the
cover baffles are located approximately midway between adjacent
shell baffles to divide each zone into two approximately equal
regions.
9. The apparatus as set forth in claim 8 wherein the tube
assembly comprises a series of hairpin portions connected by
return bend portions, one hairpin portion being located in each
zone and the return bend portions connecting adjacent hairpin
portions.
10. The apparatus as set forth in claim 9 wherein each hairpin
portion of the tube has two leg portions and a connecting portion,
one leg portion located in each region of the zone.

Description

3~6
--1--
Tube and Shell Heat Exchanger with
Baffles and Serpentine Tubing
The present invention relates to a tube and shell heat exchanger.
More specifically, the present invention relates to an improved
tube and shell heat exchanger having two sets of baffles and
serpentine tubing for achieving a counter flow heat exchange
relationship.
A typical tube and shell heat exchanger has a series of tubes
throu~h which a heat transfer media flows and a shell containing
both the tubes and a second heat transfer media in heat transfer
relation with the first heat transfer media. A series of baffles
and/or combination tub~ supports and baffles axe often provided
for directing the ~low of the second heat transfer media within
the shell in various directions in relation to the flow of heat
transfer media through the tubes.
Many tube and shell heat exchangers provide for cross flow baffles
such that the fluid flowing through the shell is directed
perpendicular to the tubes therein.
Another type of tube and shell heat exchanger is a tube in tube
heat exchanger having two coaxial tubes of different dia~eter, one
located within the other. ~he first heat transfer media flows in
the internal tube and the second heat transfer media flows within
: i ,
'

3~
the larger tube such that the two heat transfer media flow in
opposite directions and heat energy is transferred between them
through the inner tube.
The present invention concerns a tube and shell structure for
accomplishing with a tube and shell heat exchanger the same
counter flow relationship as a tube in tube heat exchanger. A
series of baffles located in a casing coact with a series of
baffles secured to the cover such that a serpentine tube may be
arranged within the heat exchanger. Flow through the tube is in a
direction opposite to the flow through the shell such that a
counter flow heat exchanger is provided.
The invention includes a casing or shell with a number of spaced
parallel shell baffles. A serpentine tube is inserted within the
shell such that a loop of the tubing extends between adjacent
shell baffles~ A cover having a series of cover baffles is then
inserted such that the cover baffles extend between the legs of
each loop such that when assembled there is provided a serpentine
tube and a serpentine path for fluid flowing in heat transfer
relations with the tube by the combination of baffles from the
shell and the cover.
This invention will now be described by way of example, with
reference to the accompanying drawings in which Figure 1 is a view
of the assembled heat exchanger with a portion of the casing
removed to expose the two sets of baffles and the tubing.
~igure 2 is a perspective view of the cover assembly of the heat
exchanger.
~igure 3 is a perspective view of ~he tube assembly of the heat
exchanger.

~ ~$~36
3-
Figure 4 is a perspective view of the shell assembly of the heat
exchanger.
The embodiment of the invention described below is for use as a
S chiller in a vapor compression refrigeration circuit and as such
is used to cool a liquid for circulation to an enclosure to be
conditioned. It is to be understood that this heat exchanger
finds like applicability in other applications such as a condenser
and that it is not limited in scope to this particular use.
Referring first to Figures 2, 3 and 4, perspective views of the
three assemblies of the heat exchanger, it can be seen that these
three principle components are assembled to comprise the heat
exchanger.
In Figure 4 there is shown the shell assembly 20 having a casing
22 with an opening 25 at one end. Mounted within shell assembly
20 are shell baffles 24 spaced from each other and located in
parallel planes. The shell baffles 24 divide the shell into a
plurality of zones 70. Each zone 70 is the space between adjacent
shell baffles. It can also be seen in Figure 4 that the shell
baffles extend from one end of the casing to a termination point
which is spaced from the opening of the casing.
In Figure 3, tube assembly 38 is shown wherein serpentine tubes 30
are manifolded to comprise the heat exchanger. Inlet tube 31 is
connected to distributor 33, which distributes refrigerant to four
capillary tubes 35 9 one capillary tube being connected to each
serpentine tube 30. The tube is arranged in a serpentine
co~figuration and connects to tube collectors 37. Refrigerant
flow is then merged into collector 36 which results in a single
refrigerant flow out of the heat e~changer through outlet 32.
The serpentine arrangement of this heat exchanger may be viewed as
comprising hairpin sections 51 and return bend portions 55. The
. ~

--4--
hairpin portion of tube 30 is that portion within the dotted line
designated 51 and having leg portions 53 and connecting portion 54
connecting the two leg portions to each other. Additionally shown
within a separate dotted line is return bend portion 55 which
connects the legs oE the adjacent hairpin portions. Consequently,
it may be thought of that the entire serpentine arrangement
consists of a series of hairpins and return bends connected to
each other. Of course it is understood that this may be but a
single piece of tubing bent to this particular configuration.
Cover assembly 40 may be seen in Figure 2. Cover plate 42 is
adapted to fit over opening 25 of the shell assembly to form a
fluid tight container therewith. Cover plate 42 has openings 45
therein through which inlet tube 31 and outlet tube 32 extend.
Additionally, cover plate 42 has openings 46 and 47 through which
the water or other fluid to be chilled may circulate through the
heat exchanger. Cover baffles 44 are shown extending from the
cover inwardly, said baffles terminating prior to reaching the far
side of the casing.
Referrin8 now to Figure 1 there may be seen an assembled view of
the heat exchanger. Therein it will be seen the corresponding
relationship of baffles 44A through 44F extending from the cover
and baffles 24A through 24~ extending from the casing. As can be
seen in Figure 1, the baffles 24A through 24E divide the heat
exchanger into six zones 70. Additionally? baffles 44A through
44F divide each of the zones 70 into two regions. Hence it can be
seen that the serpentine tubing as arranged has a hairpin 51
located within each zone and a leg portion of each hairpin locatPd
within a region of each zone.
Connecting portion 54 of hairpin 51 secures the two leg portions
of the hairpin and extends in the space between the end of the
cover baffles 44 and casing 22. Likewise return bend portion 55

2~`3~
connects adjacent hairpins and extends through the space between
the ends of shell bafEles 2~ and cover plate 42.
It can be seen in Figure 1 that refrigerant enters the heat
exchanger through inlet tube 31, flows through the distributor and
the capillary tubes into tubes 30 and then follows the serpentine
configuration through the heat exchanger until it exits the heat
exchanger at outlet 32. Conversely, water or other liquid enters
through inlet ~6 and flows along the path created by the baffles.
The water flows, as seen in Figure 1, from left to right along the
bottom of the heat exchanger around the end of cover baffle 44F
and from right to left around the end of shell baffle 24E and from
left to right across the heat exchanger and around the end of
cover baffle 44E, from right to left across the heat exchanger and
around the end of cover baffle 24D, from left to right across the
heat exchanger and around the end of cover baffle 44D and from
right to left across the heat exchanger and around the end of
shell baffle 24C and so on back and forth across the heat
exchanger until it flows from right to left across the top of the
heat exchanger and out outlet 47. It can thus be seen that the
heat exchanger has been provided where the water or other liquid
to be cooled flowing therethrough is in complete counter current
flow to the refrigerant flowing through the tube.
It is to be understood that this small and efficient heat
exchanger may be manufactured from a variety of material including
plastic. Copper tube may be well adapted to be utilized with a
plastic casing and cover and plastic baffles to provide for a
safe, economical, reliable and highly efficient compact heat
exchanger.
The assembly of the heat exchanger is accomplished by inserting
the tube assembly 38 into shell assembly 20 and then inserting
cover assembly 40 into shell assembly 20 with the cover baffles
extending bet~een the hairpins of the tube assembly to form the

3~
--6--
heat exchanger assembly. Appropriate sealing means may be used to
provide a secure fit between the cover assembly and the shell
assembly. Appropriate connections may be made at outlets 46 and
47 to provide for water flow therethrough as well as refrigerant
connections with the refrigerant tubing.
The refrigerant tubing as shown may be the evaporator of a
refrigeration circuit wherein refrigerant undergoes a pressure
drop through the capillary tubes and changes state from a liquid
to a gas absorbing heat energy from the water to be cooled in the
heat exchanger. However, the application of this heat exchanger
as the evaporator or chiller of a refrigeration circuit or even to
a heat exchanger having refrigerant and water is not considered a
limitation of the present invention. Any heat transfer between
two media may be accomplished USillg this heat exchanger.
The invention has been described in detail with particular
reference to a preferred embodiment thereof but will be understood
that variations and modifications can be effected within the
spirit and scope of the invention.
~s .