Heat exchanger

Heat exchanger comprising at least one pipe bundle (5, 27, 31) for a first fluid, a jacket (1, 17) surrounding said pipe bundle (5, 27, 31), closed at each end by end pieces (2, 23, 24) through which the pipes (5, 27, 31) extend, and with at least one entrance (3, 29, 33) and one exit (4, 30, 32) for a second fluid, with baffle walls (6, 39) between the entrance and exit, perpendicular to the pipes (5, 27, 31), for reversing the direction of flow of the second fluid, whereby said baffle walls leave a passage (10) for said second fluid alternately on one side and the other of the jacket (1, 17), characterised in that the baffle walls (6, 39) are formed by at least one baffle plate (7, 28, 34) and at least one wall (8, 37, 38) extending over part of the inner circumference of the jacket (1, 17) and pointing inwards, to which is connected the outer edge of the baffle plate (7, 28, 34), so that where there is no wall (8, 37, 38), the passage (10) for the second fluid remains open.

The invention concerns a heat exchanger which comprises at least one bundle 
of pipes for a first fluid, a jacket surrounding said pipes, closed at 
either end by end pieces through which the pipes extend and having at 
least one entrance and exit for a second fluid, and baffle walls between 
the entrance and exit, perpendicular to the pipes, to reverse the flow of 
the second fluid, said baffle walls having a free passage for said second 
fluid alternately at one side and the other of the jacket. 
DISCUSSION OF THE PRIOR ART 
In known heat exchangers of this type with a cylindrical jacket, the 
baffles consist of baffle plates in the form of a circle cut off at one 
side, with a diameter equal to the inside diameter of the jacket. Said 
baffle plates are mounted in the jacket such that they leave open 
successive passages for the second fluid perpendicularly opposite each 
other. In such heat exchangers the flow of the second fluid is partially 
perpendicular but partially also parallel to the bundle, which limits the 
heat transfer. 
Further, said known heat exchangers contain dead corners, and furthermore 
dead spaces can form between the final baffles and the end plates if the 
bundle is incorrectly positioned, in which the second fluid is more or 
less stationary, leading to accumulation of sediment and locally high 
temperatures, resulting in lower heat transfer as well as corrosion. Also 
in the case of said known heat exchangers, it is difficult for the baffles 
next to the passage to be connected in a leakproof manner to the jacket. 
Leaks between the jacket and the edge of the baffle also reduce the 
cooling power. 
Said known heat exchangers are also difficult to adjust, for example to 
obtain a higher speed of the second fluid. They are calculated to work in 
an optimum manner at a certain temperature and flow rate of the fluid. A 
large reduction in the flow rate of the second fluid reduces the heat 
exchanging capacity, due to the lower speed of said second fluid, and due 
to a lower temperature difference between the fluids. 
SUMMARY OF THE INVENTION 
The present invention has as its aim to avoid these disadvantages and to 
provide a heat exchanger which is relatively cheap but which nevertheless 
offers excellent heat transfer, without dead corners, and which in one 
embodiment can also be adjusted in an economical manner as regards the 
flow of the second fluid and so as to offer the possibility of mounting 
several pipe bundles for the first fluid in the same jacket. 
This aim is achieved according to the invention in that the baffles are 
formed by at least one baffle plate and at least one wall stretching over 
part of the inside circumference of the jacket and facing towards the 
inside, to which the outside edge of the baffle plate is connected, so 
that the passage for the second fluid remains where there is no wall. 
The walls standing on the jacket can form a single piece with the jacket or 
can be loose walls, or a number of the walls can be fixed and a number 
loose. 
By using loose walls it is easy to adjust the flow of the second fluid by 
removing or adding walls. 
In a preferred embodiment of the invention, the heat exchanger has at least 
one transverse partition between successive baffle walls and/or an outer 
baffle wall and an end piece, perpendicular to the pipes, where said 
partition lies at a distance from the inside of the jacket over part of 
its outer edge. 
As a result of this transverse partition, the flow of the second fluid is 
not reversed but is divided into parallel, smaller flows, so that a more 
transverse flow of said fluid over the pipes is obtained, and thus even 
better heat transfer. By placing loose walls on the jacket around the 
transverse partitions, extra baffle walls can easily be formed, with the 
transverse partitions becoming baffle walls. Conversely, by removing a 
loose wall around a baffle plate, the baffle wall can be made to 
disappear, with the baffle plate still functioning as transverse 
partition. 
Said transverse partition can have the same size and shape as the baffle 
plates, only it is not connected to a wall on the inside of the jacket. 
In an advantageous embodiment of the invention, there is a seal between a 
wall on the inside of the jacket and the outside of a baffle plate. 
In this embodiment in particular, leak flows between the baffle plate and 
the wall are avoided, and the full flow of the second fluid has to flow 
through the passage formed by the interruption in the wall. 
In the normal embodiment of the invention, the jacket is partly cylindrical 
and the baffle plates are round, with a diameter that fits in the inner 
diameter of the jacket. The jacket widens at opposite sides to form 
channels in which the flow of the second fluid is redirected. 
In this case the heat exchanger normally comprises only one pipe bundle for 
the first fluid. 
The heat exchanger can also comprise more than one pipe bundle, with the 
bundles parallel to each other and surrounded by one jacket, whereby one 
of the pipe bundles is longer than the other, and the baffle walls extend 
over the various bundles where they lie next to each other. 
In this embodiment, the baffle walls which extend over several pipe bundles 
are advantageously formed by a baffle plate on each of the bundles and at 
least a wall on the inside of the jacket which shuts off the opening 
between the two baffle plates and which shuts off the opening between each 
of the baffle plates and the inside of the jacket, with the exception of 
the passage. 
In this case the heat exchanger can have a cylindrical section of jacket 
for each pipe bundle, so that the inside spaces of adjacent jacket 
sections communicate with each other via a passage, and each baffle wall 
which extends over neighbouring bundles comprises a round baffle plate on 
each bundle, a wall on each of the wall sections which connects to the 
corresponding baffle plate and a wall situated in the passage and 
connecting to the neighbouring baffle plates. 
In a particular embodiment of the invention, at least one of the passages 
between the baffle walls and the jacket, where said passages are formed by 
the interruptions in the walls on the inside of the jacket, is closed off 
by a wall standing on said inside with a calibrated passage. 
In addition to the entrance and exit near its ends, the jacket can also 
have a second entrance and exit, in which case there is a baffle wall 
between said second entrance and exit, with a wall with a calibrated 
passage mounted in the passage of said baffle wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The heat exchanger shown in FIGS. 1 and 2 essentially comprises a jacket 1 
both of whose ends are closed by an end piece 2 and which near one end has 
an entrance 3 and near the other end an exit 4, together with a pipe 
bundle 5 for a first or primary fluid, extending parallel to the 
longitudinal direction of the jacket 1 and whose ends extend through the 
end pieces 2, and a number of baffle walls 6 mounted perpendicular to the 
pipes 5 inside the jacket 1. 
This jacket 1 is mostly cylindrical, but widens at two points diametrically 
opposite each other so as to form channels 48 through which the fluid can 
flow. 
Characteristic of the invention is the fact that said baffle walls 6 are 
formed by a round baffle plate 7 through which the pipes 5 extend and 
whose diameter is slightly smaller than the inside diameter of the jacket 
1, and by a wall 8 projecting inwards, standing on the inside wall of the 
jacket 1, in one of the channels 48, where said wall 8 fits against the 
outside edge of the baffle plate 7 through the intermediary of a seal 9, 
thus closing off channel 48. The seal 9 surrounds the baffle plate 7 and 
also forms a seal between the baffle plate 7 and the inside of the 
cylindrical part of the jacket 1. 
The wall 8 extends over only part of an inside circumference of the jacket 
1, so as to close off one single channel 48, so that on one side of the 
jacket 1, namely at the other channel 48, a passage 10 remains open. 
The successive walls 8 are placed so that said passages 10 stand at the 
location of the baffle walls 6 alternately at one side of the jacket 1 in 
one channel 48 and at the opposite side in the other channel 48, so that 
the second fluid, which enters the space between the pipes 5 and the 
jacket 1 via the entrance 3, is forced to flow in a zig-zag towards the 
exit 4. The direction of flow of the second fluid is indicated in FIG. 1 
by the arrows 11. 
Between successive baffle walls 6 and between the outer baffle walls 6 and 
the end pieces 2 are mounted each time two round, transverse partitions 12 
with the same diameter as the baffle plates 7. There is an open space 
around the whole circumference of these transverse partitions 12. In 
contrast to the baffle walls 6 the transverse partitions 12 do not change 
the direction of flow of said fluid, but divide it into three parallel, 
smaller flows. 
The exact positioning of the pipe bundle 5 with respect to the baffle 
plates 7 and the transverse partitions 12, so that the baffle plates 7 fit 
against the walls 8, is ensured not only by the end pieces 2 but also by a 
number of bars 13 parallel to the pipes 5, said bars 13 running through 
recesses in the baffle plates 7 and in the transverse partitions 12 and 
being attached at their ends in the end pieces 2. 
In order to assemble the pipe bundle 5 in the jacket 1, with the baffle 
plates 7 and transverse partitions 12 attached, one of the end pieces 2 is 
formed by an inner, round part 14 with the same diameter as the baffle 
plates 7 and an annular outer part 15 which can be fitted round the part 
14. The one-piece end piece 2 and the part 14 of the two-piece end piece 2 
are attached to the pipe bundle 5. The pipe bundle 5 is slid forward 
through the jacket 1 together with the part 14 until the one-part end 
piece 2 fits against the jacket 1, whereupon the annular part 15 is 
attached round the part 14 and fitted against the other end of the jacket 
1. 
The heat exchanger can be used as a cooler, whereby the first or primary 
fluid, usually a gas, flows through the pipes 5. The second fluid is then 
a coolant, usually water, which flows from the entrance 3 to the exit 
according to the arrows 11. Due to the presence of the baffle plates 7 and 
additionally the transverse partitions 12, the direction of flow of the 
cooling fluid is practically perpendicular to the pipes 5 at every point, 
thus obtaining excellent heat transfer. The cooling fluid does not stand 
stationary at any point, and dead corners are avoided. An even flow of 
cooling fluid is obtained. The sealing between the baffle plates 7 and the 
walls 8 or the cylindrical part of the jacket 1 is ensured, so that the 
cooling fluid can only flow through the passages 10. 
The number of walls 8 and thus the number of baffle walls 6 can be adjusted 
according to the flow rates of the fluids and the required heat transfer. 
Thus a wall 8 can be placed at the point of two transverse partitions 12 
between two neighbouring baffle walls 6 as shown by the dotted line in 
FIG. 1. In this way, these transverse partitions 12 form baffle plates 7 
which together with the walls 8 form baffle walls 6. Adding or even 
possibly removing walls 8 in this way can be done when manufacturing the 
jacket 1, in which case said walls 8 can be fixed and thus form a single 
part with the jacket 1. However, it is easier if all or at least a number 
of said walls 8 are loose walls which can be fitted on the inside of the 
jacket 1 before the pipe bundle 7 is inserted. For this purpose, said 
jacket 1 is provided on the inside with grooves 16 in the channels 48, for 
positioning said loose walls 8. 
In this way, it is possible to ensure that there are sufficient baffle 
walls 6 in the jacket 1 to give sufficient speed to the cooling fluid even 
at minimum flow rate of said cooling fluid. The path of the cooling fluid 
over the pipe bundles 7 can be controlled and thus the heat transfer 
adjusted by means of standardised elements, namely walls 8 in combination 
with round plates which are attached to the pipe bundle 5 and form baffle 
plates 7 or transverse partitions 12 as required. 
Not only can the flow of the secondary or second fluid within the jacket 1 
be adjusted, but also two heat exchangers, each with their own pipe bundle 
5 can easily be combined to form a single heat exchanger as shown in FIGS. 
3 and 4. 
In this embodiment, the heat exchanger comprises a jacket 17 consisting of 
a top, partly cylindrical jacket part 18 with a longitudinal opening 19 
underneath extending over part of its length, a bottom, partly cylindrical 
jacket part 20 located below said opening 19, with its longitudinal axis 
parallel to the longitudinal axis of the jacket part 18, and with a 
longitudinal opening 21 above, the same size as the opening 19 and exactly 
opposite to it, and a connecting part 22 fitted to the jacket parts 18 and 
20 and forming a passage between the inside spaces of the jacket parts 18 
and 20. The jacket part 18 widens above so as to form a channel 48, while 
the jacket part 18 similarly widens below so as to form a channel 48. 
At one end, the jacket parts 18 and 20 are closed off by their end piece 
23, while the other end of the jacket parts 18 and 20 are closed off by a 
two-part end piece 24 consisting of a round inner part 25 and an annular 
part 26 fitted round the part 25. 
The bottom jacket part 20 and the connection 22 have the same length, which 
as shown--but not necessarily--is smaller than the length of the jacket 
part 18. 
In the jacket part 18 there is a pipe bundle 27. The pipes 27 are held by 
their ends in the end piece 23 and the part 25 of the end piece 24. 
Mounted perpendicularly on the pipes 27 are baffle plates 28 whose 
diameter fits in the diameter of the wall part 18. 
Near each of the ends, the jacket part 18 has an entrance 29 and exit 30 
respectively, for the second fluid, for example a coolant. 
In the bottom jacket part 20 there is a pipe bundle 31 arranged in a 
similar manner, with the ends of the pipes held in the corresponding end 
piece 23 and the part 25 of the corresponding end piece 24. 
Approximately in the middle between its ends, the jacket part 20 has an 
extra exit 32 and next to it an extra entrance 33. 
Round baffle plates 34 are also fitted on the pipes 31 in the jacket part 
20, whereby the diameter of said baffle plates 34 fits in the inside 
diameter of said jacket part 20. 
In the connection 22 are a number of walls 35 perpendicular to the 
longitudinal axes of the jacket parts 18 and 20, connecting through the 
intermediary of a seal 36 to a baffle plate 28 in the top jacket part and 
a baffle plate 34 in the bottom jacket part 20. 
Each of the walls 35, together with the baffle plates 28 and 34 connecting 
to it, or with a wall 37 standing in the channel 48 of the top jacket part 
18, or a wall 38 standing in the channel 48 of the bottom jacket part 20, 
forms a complete baffle wall 39. The walls 37 and 38 which fit on the 
baffle plate 28 and the baffle plate 34 respectively through the 
intermediary of the seal 36, are located so that neighbouring baffle walls 
39 form a passage 10 for the second fluid or coolant alternately on one 
side and the opposite side of the jacket 17. 
Also in this embodiment, the walls 37 and 38 can either be fixed or loose. 
The path covered by the second fluid can therefore be adjusted by adding 
or removing loose walls. This path is shown in FIG. 3 by arrows 11. 
One of the baffle walls 39 is located between the exit 32 and the entrance 
33 with its passage 10 at the side of said entrance and exit. A pipe 40 
connects to the exit 32, connecting via a circuit 41 back to the entrance 
33. In the passage 10 between said baffle wall 39 and the inner wall of 
the jacket part 20 is a wall 42 with a calibrated passage 43 in a similar 
manner to a wall 37 or 38 loose-mounted on the inside of the jacket part 
20. As a result, part of the second fluid flows not through the pipe 40 
but via the passage 43, thus enabling the pressure drop in the circuit 41 
to be reduced. 
A supply pipe 44 with a valve 45 connects to the entrance 29, while a 
discharge pipe 46 with a temperature gauge 47 connects to the exit 30. The 
flow rate of the second fluid can be adjusted by means of the valve 45 
according to the temperature measured by the gauge 47. Where the pipe 
bundle 31 is situated next to the pipe bundle 27, the second fluid is 
forced by the baffle walls 29 to flow perpendicularly over the two pipe 
bundles. Where there are no pipes 31 next to the pipes 27, said fluid 
flows in a zig-zag inside the jacket part 18 between baffle walls 39 
formed by a baffle plate 28 and a wall 37 mounted on the inside of the 
jacket part 18 and connected to the baffle plate 28 by means of a seal 36. 
The walls 37 and 38 can either be fixed or loose. The same applies to the 
walls 35. In this embodiment, transverse partitions can also be mounted 
between neighbouring baffle walls 39. In the case where two pipe bundles 
are situated next to each other, a transverse partition can be mounted on 
each of the bundles, and these transverse partitions can be connected to 
each other by means of a wall. 
The heat exchangers described above offer very good heat transfer in an 
economical manner, while offering extensive possibilities for 
modifications using standard components, for example to have several pipe 
bundles. 
The present invention is in no way limited to the embodiments described 
above and shown in the drawings; on the contrary, such a heat exchanger 
can be made in different variants while still remaining within the scope 
of the invention.