CA2692936A1

CA2692936A1 - Heat exchanger module and heat exchanger system with projecting members

Info

Publication number: CA2692936A1
Application number: CA 2692936
Authority: CA
Inventors: Preben Jensen
Original assignee: Eurotec London Ltd; Preben Jensen
Current assignee: EUROTEC LONDON Ltd
Priority date: 2007-07-06
Filing date: 2008-05-27
Publication date: 2009-01-15
Also published as: EP2165142A1; WO2009007174A1

Abstract

The present invention relates to a heat exchanger module (2) and a heat exchanger system for transfer of heat between different media, in particular a heat exchanger module for preheating materials that are to be employed in a process for biogas production, such as liquid manure, industrial process water, sludge and/or ooze. A heat exchanger module (2) is provided, wherein the heat exchanger module has walls defining flow channels and comprising a first flow channel, the heat exchanger module comprising a first projecting member (40) attached to a wall (32A) and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the first projecting member, and wherein the first projecting member has a curved edge (42) such that dry matter or other objects in the first medium are prevented from being caught by the first projecting member and eventually blocking or narrowing the first flow channel.

Description

HEAT EXCHANGER MODULE AND HEAT EXCHANGER SYSTEM WITH
PROJECTING MEMBERS

The present invention relates to a heat exchanger module and a heat exchanger system for transfer of heat between different media, in particular a heat exchanger module for preheating materials that are to be employed in a process for biogas production, such as liquid manure, industrial process water, sludge and/or ooze.
In many biogas systems the biological material entering the system has a low temperature and requires heating before entering process tanks operating at different temperatures. On the other hand, material from the process tanks may have a high temperature and requires a lowering of the temperature.

Heat exchangers employing a heat transporting medium, such as water, for transfer of heat between two reservoirs by circulating the heat transporting medium in a closed loop submerged in the two reservoirs are known. Such heat exchangers usually have a low efficiency.

Counterflow heat exchangers for liquid manure are often built as tube in tube and require frequent cleaning. Cleaning of these heat exchangers is usually very difficult due to the construction or involves a heavy wear on the material of the heat exchanger when using acid.

Known heat exchangers have tubular flow channels of different cross sections.
For example, WO 2007/059770 describes a heat exchanger module and a heat exchanger system for heat transfer between a first fluid flowing in a first flow channel and a second fluid flowing in a second flow channel. The flow channels have a substantially uniform cross section through the heat exchanger module. Even though the heat exchanger system disclosed in WO 2007/059770 provides an improvement, there is still a need for a more efficient heat exchanger with an improved transfer of heat between the media in the respective flow channels.

It is a problem of known heat exchangers that the heat transfer between media in respective flow channels is low, which reduces the efficiency of the heat exchanger.
Accordingly it is an object of the present invention to provide a heat exchanger with improved heat transfer between two media in a heat exchanger.

It is also an object of the present invention to provide a medium flow having a substantially uniform temperature profile across the flow channel.

Further, it is among the objects of the present invention to provide a heat exchanger that has a high efficiency and that is easy to maintain, e.g. easy to clean.

It is also among the objects of the present invention to provide a heat exchanger capable of providing efficient heat exchange between different media, in particular manure, such as liquid manure, industrial process water, sludge and/or ooze.
Typically, these media are characterized by a large content of dry matter, such as organic material, e.g. straw, faeces and waste, dissolved in a liquid, such as water, urine or the like.

Accordingly, a heat exchanger module is provided, wherein the heat exchanger module has walls defining flow channels and comprising a first flow channel having one or more first sections extending along a first axis and positioned in thermal contact with a second flow channel having one or more second sections extending along the first axis for heat exchange between a first medium flowing in the first flow channel and a second medium flowing in the second flow channel. The heat exchanger module may comprise a first projecting member attached to a wall and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the first projecting member.

Further, a heat exchanger system is provided, comprising one or more heat exchanger modules as described herein. Preferably, the heat exchanger system comprises a first heat exchanger module and a second heat exchanger module that are interconnected to form a first flow channel and a second flow channel, e.g. by one or more module connectors, such as fittings.

The heat exchanger module may comprise a plurality of first projecting members attached to one or more walls and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the plurality of first projecting members. One or more of the first sections, e.g. each of the first sections, of the first flow channel may comprise one or more first projecting members, such as one, two, three, four, five, six, seven, eight, nine, ten or more first projecting members. The number of first projecting members in a first section may be chosen according to the intended use of the heat exchanger module, e.g. properties of the first medium, the length of the first section and/or desired turbulence in the first flow channel.
Furthermore, the heat exchanger module may comprise a second projecting member attached to a wall and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the second projecting member.

Additionally, the heat exchanger module may comprise a plurality of second projecting members attached to one or more walls and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the plurality of second projecting members. One or more of the second sections, e.g. each of the second sections, of the second flow channel may comprise one or more second projecting members, such as one, two, three, four, five, six, seven, eight, nine, ten, or more second projecting members. The number of second projecting members in a second section may be chosen according to the intended use of the heat exchanger module, e.g. properties of the second medium, the length of the second section and/or desired turbulence in the second flow channel.

The projecting members in the flow channels create turbulence in the media flowing in the flow channels. The turbulence causes mixing of the medium leading to a more uniform temperature profile across the flow channel. Thereby improved transfer of heat between the media flowing in the flow channels is obtained compared to a substantially laminar flow. It may be desired to have as low drop of pressure as possible from the inlet to the outlet of the flow channel to reduce the consumption of energy in moving the medium through the flow channel. However a low drop of pressure requires low turbulence in the flow, i.e. a substantially laminar flow.

Surprisingly, the present inventors have found that a considerable improvement in the heat transfer between the media and thus a more efficient heat exchanger can be obtained by employing projecting members in the flow channels. At the same time, a relatively low increase in drop of pressure has been observed. The advantages of the improvement heat transfer exceed the disadvantages of an increased drop of pressure.
Preferably, the heat exchanger module has a body with walls including a first outer wall, a first end wall, and a second end wall. In an embodiment, the heat exchanger module further comprises a second outer wall, a third outer wall, and a fourth outer wall. Further, the heat exchanger module may comprise inner walls forming a plurality of cavities or sections of flow channels in the body of the heat exchanger module.
Preferably, an inner wall forms a common wall between a first section and a second section of the first flow channel and the second flow channel, respectively. A
single wall forming a common wall between different flow channel sections provides efficient heat transfer between the media in the respective flow channels.

Preferably, the walls defining the sections of the flow channels are plane and may be parallel to the first axis. However, the walls may be curved, e.g. to form a flow channel section having a smooth, non-polygonal cross section.

Preferably, the projecting members are formed and/or attached to the walls such as to minimize the risk of catching medium and/or dry matter, such as straw or tissue in slaughterhouse waste. Dry matter or other objects caught by the projecting members may lead to blocking or narrowing of the flow channel, which thus requires cleansing.

Preferably, the first projecting member(s) and/or the second projecting member(s) is/are substantially plane. Plane members are preferred due to the production process;
however one or more of the projecting members may in an embodiment of the present invention have a curved surface to obtain a smoother redirection of the flow.

In a preferred embodiment of present invention, the first projecting member(s) and/or the second projecting member(s) is/are substantially perpendicular to the wall to which it/they are attached, e.g. to reduce the risk of deposition of medium or dry matter, such as straw. However, one or more of the projecting member(s) may be tilted in relation to the wall, e.g. at an angle from about from about 45 to 90 , such as about 65 , about 75 or about 85 .

The first projecting member(s) and/or the second projecting member(s) may form an angle with the first axis, the angle being less than 70 , such as from about 5 to about 60 , preferably from about 15 to about 45 . In a preferred embodiment of the present invention, the first projecting member(s) and/or the second projecting member(s) forms/form an angle with the first axis from about 20 to about 30 .

The projecting members may have a first edge between a first point and a second point, respectively. The projecting members may be attached, e.g. by welding, to a wall of the heat exchanger module along second edges. Preferably, the first edge is formed in such a way that dry matter or other objects in the medium are prevented from being caught by the projecting members and eventually blocking or narrowing the flow channel into which the projecting members projects.

In general, projecting members may be formed such that tangents of the first edge from a first intermediate point to a middle point along the first edge form tangent angles with the first axis, such that dry matter, e.g. straw, flowing along the first axis in the flow channel is not caught by the projecting member. Furthermore, in order to provide a flow channel adapted for flow in both directions along the first axis, projecting members may be formed such that tangents of the first edge from the middle point to a second intermediate point along the first edge form tangent angles with the first axis, such that dry matter, e.g. straw, flowing along the first axis in the flow channel is not caught by the projecting member.

In general, it is important that the first edge at least from a small distance of the first and second points, is not perpendicular to the first axis.

Preferably, the tangent angles with the first axis parallel to the second edge of the projecting member from the first intermediate point to the middle point lie in the range 5 from about -85 to about 85 , preferably in the range from about -75 to about 75 , more preferably in the range from about -60 to about 60 . In a preferred embodiment, the tangent angles with the first axis parallel to the second edge of the projecting member from the first intermediate point to the middle point lie in the range from about -45 to about 45 , such as in the range from about -30 to about 30 .

Preferably, the tangent angles with the first axis parallel to the second edge of the projecting member from the middle point to the second intermediate point lie in the range from about -85 to about 85 , preferably in the range from about -75 to about 75 , more preferably in the range from about -60 to about 60 . In a preferred embodiment, the tangent angles with the first axis parallel to the second edge of the projecting member from the middle point to the second intermediate point lie in the range from about -45 to about 45 , such as in the range from about -30 to about 30 .
Preferably, the tangent angles with the first axis parallel to the second edge of the projecting member from the first point to the first intermediate point lie in the range from about 0 to about 85 , preferably in the range from about 0 to about 60 , more preferably in the range from about 0 to about 45 .

Preferably, the tangent angles with the first axis parallel to the second edge of the projecting member from the second intermediate point to the second point lie in the range from about -85 to about 0 , preferably in the range from about -60 to about 0 , more preferably in the range from about -45 to about 0 .

The first edge may be formed by a number of linear edge portions connected by curved or rounded edge portions.

In general, first edge portions may form angles with the first axis parallel to the second edge of the projecting member in the range from about -75 to about 75 , preferably in the range from about -45 to about 45 .

The first intermediate point on the first edge is close to the first point, e.g. at a distance of about 10 mm or less than 10 mm, such as about 5 mm, 3 mm or 2 mm, from the first point, and the second intermediate point on the first edge is close to the second point, e.g. at a distance of about 10 mm or less than 10 mm, such as about 5 mm, 3 mm or 2 mm, from the second point.

Preferably, the first and second intermediate points coincide with the first and second points, respectively.

The first and/or second projecting member(s) may have a curved edge such that objects, e.g. straw, tissue from slaughterhouse waste or other objects, in the medium passing the projecting member(s) are prevented from being caught by the projecting member(s) and subsequently blocking or narrowing the flow channel.

It is an important advantage of an embodiment of the present invention that the projecting members are smooth such as to prevent deposit of medium or dry matter of the medium.

The first and/or the second projecting member(s) may have any suitable size and shape such that a desired turbulence is created in the medium in the flow channel in question. In an embodiment of the present invention, the projecting members extend about halfway into the flow channel.

In a preferred embodiment of the present invention, the projecting members are semi-oval, e.g. with a length of about 13 cm and a width of about 3.6 cm. Other shapes such as semi-circular, bell-shaped may also be employed. Typically, the projecting members are attached to the walls in such a way that there is a certain distance to neighbouring walls to further reduce the risk of deposit of medium or dry matter of the medium in the flow channel.

In a preferred embodiment, one or more of the projecting members may be formed as a circular segment constituted by the part between a chord (second edge) and an arc (first edge) of a circle, excluding the center of the circle.

In an embodiment, one or more of the projecting members may be formed as a segment constituted by the part between a chord (second edge) and an arc (first edge) of an ellipse, excluding at least one of the foci of the ellipse. Preferably, the chord is parallel to the major axis.

In a preferred embodiment of the present invention, the projecting members have an area less than 100 cm2, such as in the range from about 5 cm2 to about 90 cm2, preferably from about 20 cm2 to about 60 cm2, more preferably about 30 cm2.
Other dimensions and shapes may be contemplated according to dimensions of the flow channels.

It is an important advantage that the heat exchanger module according to the present invention can be operated with lower flow velocities for obtaining the same efficiency compared to heat exchangers without projecting members.

Further, it is an advantage of the heat exchanger module according to the present invention that a increased surface area is provided for each flow channel, leading to improved heat exchange between the first medium in the first flow channel and second medium in the second flow channel.

In a preferred embodiment of the present invention, a first section of the first flow channel abuts at least three second sections of the second flow channel.
Preferably, the first flow channel and the second flow channel have a substantially uniform cross section through the heat exchanger module.

In a preferred embodiment of the heat exchanger module, a second section of the second flow channel abuts at least three first sections of the first flow channel.
Preferably, the walls in the heat exchanger module form a plurality of cavities to form at least two flow channels. For example, first cavities may be connected via first connectors forming a first flow channel and second cavities may be connected via second connectors forming a second flow channel. A cavity may form a section of the first flow channel or the second flow channel. Preferably a section of a flow channel is connected either upstream or downstream to the other sections of the flow channel, i.e.
in series with the other sections. In an embodiment, one or more sections may be connected in parallel.

Preferably, the first flow channel and the second flow channel have common walls to improve heat exchange between media in the respective channels. For example, a first section of the first flow channel may have a common wall with at least three different second sections of the second flow channel, and a second section of the second flow channel may have a common wall with at least three different first sections of the first flow channel.

The heat exchanger module may have a first port and a second port. The first port may form an inlet and/or an outlet at an end of the first flow channel, and the second port may form an inlet and/or outlet at the other end of the first flow channel.

Further, the heat exchanger module may comprise a third port and a fourth port. The third port may form an inlet and/or an outlet for the second flow channel, and the fourth port may form an inlet and/or an outlet for the second flow channel.

The ports may have module connectors, e.g. fittings, for coupling the heat exchanger module to other heat exchanger modules and or external units such as a cleaning system or containers holding first and second media. Preferably, the module connectors when inter-coupling heat exchanger modules have a cross section corresponding to the cross section of the sections of the flow channels, which they communicate or connect.

Preferably, the first sections of the first flow channel are tubular and second sections of the second flow channel are tubular. Preferably, the first sections and the second sections extend along a straight first axis, e.g. having a length from about 0.5 m to about 10 m. In a preferred embodiment of the present invention, the sections have a length of about 3 m.

In an embodiment of the present invention, the walls of the heat exchanger module form a first flow channel with a polygonal cross section. In a preferred embodiment of the present invention, the walls of the heat exchanger module form a first flow channel with first sections having a four-sided cross section.

In an embodiment of the present invention, the walls of the heat exchanger module form a second flow channel with a polygonal cross section. In a preferred embodiment of the present invention, the walls of the heat exchanger module form a second flow channel with second sections having a four-sided cross section.

The sections of the respective flow channels may have a substantially polygonal cross section with side lengths from about 10 mm to about 200 mm, such as from about mm to about 100 mm, e.g. about 50 mm. Preferably, the sections have a four-sided cross section, e.g. a rectangular cross section and/or a square cross section, with side lengths from about 10 mm to about 200, preferably from about 25 mm to about mm, more preferably from about 30 mm to about 60 mm, such as about 40 mm or about 50 mm.

The heat exchanger module may be operated with a medium flow velocity of about 0.6 m/s to about 3 m/s, such as from about 0.8 m/s to about 1.7 m/s, e.g. about 1.2 m/s.
In a preferred embodiment of the present invention, one or more of the sections of the flow channels, preferably all, have a square cross section with a side length from about mm to about 100 mm, such as about 40 mm, about 50 mm, about 60 mm, about 70 mm, or about 80 mm.

In another preferred embodiment of the present invention, the sections of the flow 30 channels have a rectangular cross section, e.g. having the dimensions 30 mm x 40 mm or 40 mm x 50 mm.

Preferably, the first sections and the second sections of the heat exchanger module are alternately arranged in two columns including a first column and a second column such that a first section in the first column abuts two second sections in the first column and one second section in the second column. Thus, a first section in the first column may have a common inner wall with a second section in the first column, a common inner wall with another second section in the first column, and a common inner wall with a second section in the second column. Preferably, each section is delimited by or defined by at least a part of an outer wall.

The heat exchanger module may comprise first connectors. The first connectors may connect first sections to form the first flow channel or at least a part thereof.
Furthermore, the heat exchanger module may comprise second connectors. The second connectors may connect second sections to form the second flow channel or at least a part thereof.

In a preferred embodiment of the present invention, the connectors are welded to the outer walls of the heat exchanger module thereby connecting sections of the respective flow channels through openings in the outer walls. Preferably, the openings in the outer walls are rectangular and/or quadratic having a cross section corresponding to the cross section of the sections for provision of substantially uniform flow channels. In an embodiment, the connectors are secured in threaded engagement with the walls.
In an embodiment of the present invention, the connectors may connect sections of the respective flow channels through openings in the end walls.

Preferably, the first and/or the second connectors have a cross section corresponding to the cross section of the sections which they communicate or connect.
Thereby drop of pressure around the connector may be minimized or substantially avoided.
Thus, the connectors may have a polygonal cross section with a side length from about 30 mm to about 100 mm, such as a square cross section with a side length from about 30 mm to about 100 mm, such as about 40 mm, about 50 mm, about 60 mm, about 70 mm, or about 80 mm.

Preferably, the connectors are positioned near or at the ends of the first and second sections.

Further, the heat exchanger module may have one or more cleaning holes.
Preferably, one or more cleaning holes are provided for each of the cavities forming the sections of the flow channels. In a preferred embodiment, a cleaning hole for each of the cavities forming the sections of the flow channels is provided, e.g. in the first end wall of the heat exchanger module. More preferably, a cleaning hole for each of the cavities forming the sections of the flow channels may further be provided in the second end wall of the heat exchanger module. The one or more cleaning holes may comprise an engagement member, e.g. a threading or a bayonet socket that may be adapted for engagement with a plug member. The one or more cleaning holes provide user access to the different sections of the heat exchanger thereby facilitating manual cleaning or removal of blockages in the flow channel.

5 Further, the heat exchanger module may comprise one or more plug members for sealing the one or more cleaning holes. The one or more plug members comprise an engagement member, e.g. a threading or a bayonet socket, for detachable engagement with the engagement member of a cleaning hole.

It is an important advantage of the present invention that a user has easy access to the 10 different sections of the flow channels for convenient removal of any blockages that may arise during use. The plug members are readily detachable and mountable.
Preferably, the heat exchanger module is made of stainless steel, such as AISI
304 or AISI 316, however any other suitable steel type may be used.

Preferably, the heat exchanger module is made of an acid-resistant steel type.
Hereby cleaning of the heat exchanger with acidic media is rendered possible.

In an embodiment suitable for non-aggressive media, at least a part of the heat exchanger module, e.g. the inner walls and/or the outer walls, may be made of a metal having high thermal conductivity compared to stainless steel, such as black steel, aluminum, or copper. In an embodiment, the walls may be coated with an acid resistant material.

In an embodiment of the present invention, first medium having a first inlet temperature is pumped into the first flow channel through the first port, passes the first flow channel while exchanging heat with medium in the second flow channel, and leaves the first flow channel having a first outlet temperature through the second port. At the same time, a second medium having a second inlet temperature may be pumped into the second flow channel through the third port, passing the second flow channel while exchanging heat with medium in the first flow channel, and leaving the second flow channel having a second outlet temperature through the fourth port.

The heat exchanger module is in particular adapted for heat exchange between manure, e.g. liquid manure; however, the media may be any media, such as manure, e.g. liquid manure, sludge, water or other fluids in liquid and/or gaseous form, oil, natural gas, mixtures thereof, or the like.

It is an important advantage of the present invention that the heat exchanger due to its construction is compact and takes up little space compared to the amount of heat transferred.

It is an important advantage of the present invention that the heat exchanger is able to transfer large amounts of heat between the media in the respective flow channels.

It is a further advantage of the present invention that cleaning of the heat exchanger module is easy and can be performed without destroying, e.g. cutting, the heat exchanger module.

The walls of the heat exchanger module may have a thickness in the range from about 0.5 mm to about 20 mm, preferably from about 1 mm to about 10 mm. In a preferred embodiment of the present invention, the walls of the heat exchanger have a thickness from about 2 mm to about 5 mm, e.g. about 3 mm or about 4 mm. If the thickness of the walls is too small, a high pressure may not be employed, and if the thickness of the walls is too large, the transfer of heat between the first and second flow channel is reduced.

It may be desired to employ a high pressure in the flow channels. If the first pressure in the first flow channel and the second pressure in the second flow channel are substantially the same, or the pressure difference between the first flow channel and the second flow channel is small, e.g. less than 3 bar, the thickness of the inner walls of the heat exchanger module can be small, such as around 1 mm, thereby obtaining improved heat exchange between the media.

The heat exchanger module may further comprise a casing. The casing supports and strengthens the outer walls to increase the possible operating pressures of the heat exchanger module. The heat exchanger module with or without a casing may operate with media at a high pressure, e.g. up to 12 bar or more.

The heat exchanger system according to the present invention may comprise one or more heat exchanger modules as described herein, such as two, three, four, five, ten, twenty, fifty or more heat exchanger modules. In a preferred embodiment, the heat exchanger system comprises a first heat exchanger module and a second heat exchanger module as described herein. Preferably, the heat exchanger system comprises a frame carrying the one or more heat exchanger modules. Further, the heat exchanger system may comprise a plurality, e.g. two three, four or more insulation elements for insulation of the heat exchanger modules. The insulation elements may be attached to the frame, e.g. by one or more hinges and/or adapted to support on the frame.

In the heat exchanger system, one or more ports functioning as inlet/outlet of a flow channel may be provided with fittings, e.g. a T-piece, to allow easy coupling, e.g. via valves, of the flow channel to different medium loops, such as a medium loop with liquid manure and a medium loop with cleaning fluid.

Preferably, the heat exchanger system according to the invention comprises one or more module connectors, such as fittings, that connect ports of the heat exchanger modules according to a desired configuration of the heat exchanger system, e.g.
depending on the number of media to be heat exchanged, number of heat exchanger modules, etc.

Preferably, the module connectors have a cross section corresponding to the cross section of the sections of the heat exchanger modules, which they communicate or connect. Thereby drop of pressure around the module connector may be minimized or substantially avoided. Thus, the module connectors may have a polygonal cross section with a side length from about 30 mm to about 100 mm, such as a square cross section with a side length from about 30 mm to about 100 mm, such as about 40 mm, about 50 mm, about 60 mm, about 70 mm, or about 80 mm.

Preferably, first medium in a first section flows in the opposite direction of the flow of the second medium in two adjacent second sections.

The invention will now be described in further detail with reference to the enclosed drawings, wherein Fig. 1 is a perspective view of an embodiment of a heat exchanger module according to the present invention, Fig. 2 is another perspective view of the embodiment illustrated in Fig. 1, Fig. 3 shows a perspective cross section of the heat exchanger module illustrated in Fig. 1, Fig. 4 is a side view of a side of the heat exchanger module illustrated in Fig. 1, Fig. 5 is a side view of the opposite side of the heat exchanger module illustrated in Fig. 1, Fig. 6 shows the side view of Fig. 5 omitting parts of the heat exchanger module, Fig. 7 schematically illustrates a cross section of the heat exchanger module of Fig. 1 Fig. 8 schematically illustrates a cross section of a heat exchanger module according to the present invention, Fig. 9 schematically illustrates a cross section of a heat exchanger module according to the present invention, Fig. 10 schematically shows a plan view of a wall with projecting members of a heat exchanger module according to the present invention, Fig. 11 is a surface view of an exemplary projecting member, Fig. 12 is a top view of the wall illustrated in Fig. 10, Fig. 13 and Fig. 14 show different views of exemplary projecting members, Fig. 15 schematically shows a plan view of a wall of a heat exchanger module according to the present invention, Fig. 16 schematically illustrates an embodiment of a heat exchanger system according to the invention, Fig. 17 schematically illustrates operation of the heat exchanger system shown in Fig. 10, Fig. 18 schematically illustrates operation of an embodiment of a heat exchanger system according to the present invention, and Fig. 19 is a surface view of an exemplary projecting member.

In the drawings, corresponding parts of the illustrated embodiments have the same reference numerals.

Figs. 1-7 schematically show a preferred embodiment of a heat exchanger module according to the present invention. The heat exchanger module 2 has walls and comprises a first flow channel positioned in thermal contact with a second flow channel for heat exchange between a first medium flowing in the first flow channel and a second medium flowing in the second flow channel. Further, a first section of the first flow channel abuts at least three second sections of the second flow channel, e.g. the first section 6Q abuts the second sections 14C, 14D, and 14N. Further, a second section of the second flow channel abuts at least three first sections of the first flow channel, e.g. the second section 14L abuts the first sections 61, 6J, and 6S.

A first port 4 and a second port 8 in the heat exchanger module function as inlet/outlet to the first flow channel. First sections 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H, 61, 6J, 6K, 6L, 6M, 6N, 60, 6P, 6Q, 6R, 6S, 6T and first connectors 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 101, 10J, 10K, 10L, 10M, 10N, 100, 10P, 10Q, 10R, 10S form the first flow channel. A first connector connects two first sections of the first flow channel, e.g. the first connector 10A connects the first sections 6A and 6B, the first connector connects the first sections 6B and 6C, etc.

The first sections and the second sections are tubular and extend along a straight first axis A and having a length of about 3 m.

A third port 12 and a fourth port 16 function as an inlet/outlet to the second flow channel. Second sections 14A, 14B, 14C, 14D, 14E, 14F, 14G, 14H, 141, 14J, 14K, 14L, 14M, 14N, 140, 14P, 14Q, 14R, 14S, 14T and second connectors 18A, 18B, 18C, 18D, 18E, 18F, 18G, 18H, 181, 18J, 18K, 18L, 18M, 18N, 180, 18P, 18Q, 18R, 18S
form the second flow channel, each second connector connecting two second sections of the second flow channel, e.g. the second connector 18A connects the second sections 14A and 14B, the second connector 18B connects the second sections and 14C, etc.

The heat exchanger module 2 comprises first projecting members attached to the walls of the heat exchanger module extending into the first sections. In the heat exchanger module 2, each first section comprises five first projecting members and each second section comprises five second projecting members. Any suitable number of projections in a section may be employed such as up to and including ten, or more, e.g.
one, two, three, four, five, six, ten or more.

In the illustrated embodiment, the projecting members of a section are attached to the same wall, however in another embodiment of the present invention another configuration may be desired, and thus the projecting members in a section may be attached to different, e.g. neighbouring and/or opposite, walls.

The first flow channel and the second flow channel have a substantially quadratic cross section (about 40 mm X 40 mm) from the first port to the second port and from the third port to the fourth port, respectively.

The ports 4, 8, 12, 16 have fittings 4', 8', 12', 16' for connection to other heat exchanger modules or external units.

The heat exchanger module 2 has a first outer wall 20, a second outer wall 22, a third outer wall 24, a fourth outer wall 26, a first end wall 28, and a second end wall 30.

Further, the heat exchanger module 2 comprises inner walls 32A, 32B forming a plurality of cavities forming sections of the flow channels in the heat exchanger module.
Preferably, the inner walls of the heat exchanger separate two adjacent sections thereby forming a common wall. The outer walls 20, 22, 24, 26 have a thickness of 5 about 2 mm, and the inner walls 32A, 32B have a thickness of about 2 mm. The thickness of the walls may be selected according to desired operating pressure and optimum heat transfer.

The first connectors and the second connectors connect first sections and second sections, respectively, via openings in the outer walls of the heat exchanger module.
10 A plurality of cleaning holes is formed in the first end wall 28, preferably one cleaning hole for each cavity forming a section of a flow channel. In an embodiment according to the present invention, a plurality of cleaning holes are formed in the second end wall 30 (not shown) preferably one cleaning hole for each cavity forming a section of a flow channel. The one or more cleaning holes have a threading for engagement with a 15 corresponding plug member.

The heat exchanger module 2 further comprises a plurality of plug members 34 for sealing the cleaning holes in the end walls. The plug members 34 have a threading for engagement with the engagement member of a cleaning hole. The plug members may be unscrewed, thereby providing user access to the heat exchanger module.

Fig. 7 schematically illustrates a cross section of the heat exchanger module according to the present invention. Inner walls 32A, 32B separate cavities or first sections 6A, 6B,..., 6T forming a part of the first flow channel from cavities or second sections 14A, 14B,..., 14T forming a part of the second flow channel. Each section of the first and second flow channels except the first sections 6A, 6T and the second sections 14J, 14K abuts three different sections of the other flow channel.
The heat exchanger module 2 has twenty first sections 6A, 6B, ..., 6T and twenty second sections 14A, 14B, ..., 14T. The first sections and the second sections are arranged in two columns including a first column comprising ten first sections 6A, 6B, ..., 6J and ten second sections 14K, 14L, .., 14T, and a second column comprising ten first sections 6K, 6L, ..., 6T and ten second sections 14A, 14B, .., 14J. The sections have a square cross section with a side length of 40 mm. In the heat exchanger module 2, the projecting members are attached to the vertical inner walls 32A. In another embodiment, one or more projecting members may be attached to the horizontal inner walls 32B and/or to the outer walls 20, 22, 24, 26. Different projecting members of a section extending into a flow channel may be attached to different walls defining the section.

Fig. 8 schematically illustrates a cross section of another embodiment of the heat exchanger module 102 corresponding to the embodiment of Fig. 1-7 except that the heat exchanger module 102 has fewer first and second sections and accordingly fewer first and second connectors. The heat exchanger module 102 has ten first sections 6A, 6B, ..., 6J and ten second sections 14A, 14B, ..., 14J. The first sections and the second sections are arranged in two columns including a first column comprising five first sections 6A, 6B, ..., 6E and five second sections 14F, 14G, .., 14J, and a second column comprising five first sections 6F, 6G, ..., 6J and five second sections 14A, 14B, .., 14E. The sections have a square cross section with a side length of about 40 mm.
First connectors (not shown) connect the first sections and second connectors connect the second sections to form the first flow channel and the second flow channel, respectively.

Fig. 9 schematically illustrates a cross section of another embodiment of the heat exchanger module 202 corresponding to the embodiment of Fig. 1-7 except that the heat exchanger module 202 has fewer first and second sections and accordingly fewer first and second connectors. The exchanger module 202 has four first sections 6A, 6B, 6C, 6D and four second sections 14A, 14B, 14C, 14D. The first sections and the second sections are arranged in two columns including a first column comprising two first sections 6A, 6B and two second sections 14C, 14D, and a second column comprising two first sections 6C, 6D and two second sections 14A, 14B. The sections have a square cross section with a side length of about 50 mm. First connectors (not shown) connect the first sections and second connectors connect the second sections to form the first flow channel and the second flow channel, respectively.

Fig. 10 shows an embodiment of a vertical inner wall 32A that may form one or more of the vertical inner walls of the heat exchanger modules 2, 102, 202. Five projecting members 40 are attached to one side of the vertical inner wall 32A extending into a section of a flow channel, e.g. into a first section 6C of the first flow channel thereby forming first projecting members. The plane projecting members 40 are perpendicular to the vertical inner wall 32A and each form an angle a with the first axis A.
The angle a may be less than 70 . In the illustrated embodiment, the projecting members form an angle a with the first axis from about 20 to about 30 . On the other side of the vertical inner wall 32A corresponding projecting members are attached and extending into another section of a flow channel, e.g. into the second section 14H in Fig. 7 thereby forming second projecting members. Preferably, a first projecting member and a second projecting member are formed in one piece and mounted, e.g. by welding, in a slit in a wall.

Fig. 11 shows the projecting member 40 in Fig. 10 in surface view. The projecting member 40 has a semi-oval shape with a curved edge 42 and a substantially straight edge 44. The projecting member 40 is attached, e.g. by welding, to a wall of the heat exchanger module along the straight edge 44. The projecting member 40 may form a first projecting member and/or a second projecting member. The width D, is 3.6 cm corresponding to half the width of the flow channels in the heat exchanger module 2, and the length D2 is about 13 cm. D, and D2 may have any suitable size, e.g.
D, may be in the range from about 0.5 cm to about 10 cm and D2 may be in the range from about 2 cm to about 30 cm, depending on the proportions of the flow channel and the media flowing in the flow channel.

The curved first edge 42 between a first point 45a and a second point 45b.The first edge 42 is formed in such a way that dry matter or other objects in the medium are prevented from being caught by the projecting members and eventually blocking or narrowing the flow channel into which the projecting members projects.

The projecting member 40 is formed such that tangents of the first edge 42 from a first intermediate point 47a to a middle point 47b along the first edge form tangent angles R, with the first axis in the range from about 0 to about 45 , such that dry matter, e.g.
straw, flowing along the first axis in the flow channel is not caught by the projecting member. Furthermore, in order to provide a flow channel adapted for flow in both directions along the first axis, the projecting member 40 is formed such that tangents of the first edge 42 from the middle point 47b to a second intermediate point 47c along the first edge 42 form tangent angles P2with the first axis in the range from about -45 to about 0 , such that dry matter, e.g. straw, flowing along the first axis in the flow channel is not caught by the projecting member. In the projecting member 40, the first intermediate point 47a is at a distance from the first point 45a of about 3 mm, and the second intermediate point 47c is at a distance from the second point 47c of about 3 mm.

In general, it is important that the first edge, at least from a small distance of the first and second points, is not perpendicular to the first axis.

Preferably, the tangent angles P from the first intermediate point to the middle point lie in the range from about -85 to about 85 , preferably in the range from about -60 to about 60 , more preferably in the range from about -45 to about 45 .

Preferably, the tangent angles from the middle point to the second intermediate point lie in the range from about -85 to about 85 , preferably in the range from about -60 to about 60 , more preferably in the range from about -45 to about 45 .

Fig. 12 shows a top view of a part of the inner wall 32A of Fig. 10. A first projecting member 40A and a second projecting member 40B are attached to the wall 32A as one member inserted in a slit in the wall 32A.

Fig. 13 shows a vertical inner wall 32A with exemplary projecting members 46, 48, 50 extending perpendicularly from the wall 32A. The projecting members 46, 48, 50 have curved surfaces for mixing medium flowing in the flow channel, which the projecting members 46, 48, 50 extend into. In an embodiment, the projecting members 46, 48, 50 may be plane.

Fig. 14 shows plan surface views of the curved projecting members 46, 48, 50.
In an embodiment of the present invention, the projecting members may be plane. The projecting members 46, 48, 50 have first edges 46a, 48a, 50a, respectively, between a respective first point 45a and second point 45b. The projecting members 46, 48, 50 are attached, e.g. by welding, to a wall of the heat exchanger module along straight second edges 46b, 48b, 50b, respectively.

The first edges 46a, 48a, 50a are formed in such a way that dry matter, e.g.
straw, or other objects in the medium are prevented from being caught by the projecting members 46, 48, 50 and eventually blocking or narrowing the flow channel into which the projecting members 46, 48, 50 projects.

The projecting member 46 is formed such that tangents of the first edge 46a from a first intermediate point 47a to a middle point 47b along the first edge 46a form tangent angles P, with the first axis parallel to the second edge 46b in the range from about 0 to about 75 to avoid blockage or narrowing of the flow channel by dry matter being caught by the projecting member. Further, the projecting member 46 is formed such that tangents of the first edge 46a from the middle point 47b to a second intermediate point 47c along the first edge 46a form tangent angles P2 with the first axis parallel to the second edge 46b in the range from about -75 to about 0 . In the projecting member 46, the first intermediate point 47a is at a distance from the first point 45a of about 2 mm, and the second intermediate point 47c is at a distance from the second point 47c of about 2 mm. The first edge 46a has two curved edge portions 49a, 49b and a substantially straight edge portion 49c.

The projecting member 48 is formed such that tangents of the first edge 48a from a first intermediate point 47a to a middle point 47b along the first edge 48a form tangent angles P, with the first axis parallel to the second edge 48b in the range from about 0 to about 60 to avoid blockage or narrowing of the flow channel by dry matter being caught by the projecting member. Further, the projecting member 48 is formed such that tangents of the first edge 48a from the middle point 47b to a second intermediate point 47c along the first edge 48a form tangent angles P2 with the first axis parallel to the second edge 48b in the range from about -60 to about 0 . In the projecting member 48, the first and second intermediate points 47a, 47b coincide with the first and second points 45a, 45b, respectively.

The projecting member 50 is formed such that tangents of the first edge 50a from a first intermediate point 47a to a middle point 47b along the first edge 50a form tangent angles R, with the first axis parallel to the second edge 50b in the range from about 0 to about 30 to avoid blockage or narrowing of the flow channel by dry matter being caught by the projecting member. Further, the projecting member 48 is formed such that tangents of the first edge 50a from the middle point 47b to a second intermediate point 47c along the first edge 50a form tangent angles P2 with the first axis parallel to the second edge 50b in the range from about -30 to about 0 . In the projecting member 50, the first and second intermediate points 47a, 47b coincide with the first and second points 45a, 45b, respectively. The first edge 50a has three straight edge portions 51 a, 51 b, 51 c connected by curved or rounded edge portions 53a, 53b.

Fig. 15 shows another embodiment of a vertical inner wall 32A with projecting members 40, 52 on both sides of the wall. The angles a, and a2 may be the same or different, e.g. 20 and 30 respectively.

Fig. 16 and Fig. 17 schematically illustrate a heat exchanger system according to the invention. The heat exchanger system 302 comprises a first heat exchanger module 2A
and a second heat exchanger module 2B according to the invention. In the illustrated embodiment heat exchanger modules 2A and 2B correspond to the heat exchanger module 2 schematically illustrated in Figs. 1-7. The heat exchanger system comprises a frame 304 carrying the heat exchanger modules 2A and 2B. Further, the heat exchanger system may comprise a plurality of insulation elements. The heat exchanger system 302 comprises six insulation elements 306, whereof two are not shown.
The insulation elements 306 assist in insulating the heat exchanger system. The insulation elements 306 may be movably attached to the frame 304, e.g. by one or more hinges, for providing easy access to the heat exchanger modules.

The first port 4A of the first heat exchanger module 2A and the first port 4B
of the second heat exchanger module 2B function as an inlet/outlet of a flow channel in the heat exchanger system 302. The second port 8A of the first heat exchanger module 2A
and the second port 8B of the second heat exchanger module 2B are connected by a 5 module connector 308 thereby forming a flow channel 316 from the first port 4A to the first port 4B.

The fourth port 16A of the first heat exchanger module 2A and the fourth port 16B of the second heat exchanger module 2B function as an inlet/outlet of a flow channel in the heat exchanger system 302. The third port 12A of the first heat exchanger module 10 2A and the third port 12B of the second heat exchanger module 2B are connected by a module connector 312 thereby forming a flow channel 318 from the fourth port 16A to the fourth port 16B.

One or more ports functioning as inlet/outlet of a flow channel may be provided with fittings, e.g. a T-piece, to allow easy coupling, e.g. via valves, of the flow channel to 15 different medium loops, such as a medium loop with liquid manure and a medium loop with cleaning fluid.

In the heat exchanger system illustrated in Fig. 16, each of the heat exchanger modules 2A and 2B are provided with a casing 314A and 314B, respectively, for reinforcement of the outer walls of the respective modules.

20 Further, Fig. 17 schematically illustrates a way of operating the heat exchanger system 302. First medium having a temperature TA enters the heat exchanger system at A
through the first port 4A, passes through the heat exchanger system and leaves the system through the first port 4B at B having a temperature TB. Second medium having a temperature Tc enters the heat exchanger system at C through the fourth port 16B, passes through the heat exchanger system and leaves the system through the fourth port 16A at D having a temperature TD. Thereby first medium in a first section flows in the opposite direction of the flow of the second medium in two adjacent second sections.

Fig. 18 illustrates an embodiment 402 of a heat exchanger system according to an alternative embodiment of the present invention. In the heat exchanger system 402, the second port 8A of the first heat exchanger module and the second port 8B of the second heat exchanger module are connected by a module connector or fittings preferably having a cross section corresponding to the sections of the heat exchanger modules, thereby forming a main flow channel 406 from the first port 4A of the first heat exchanger module 2A to the first port 4B of the second heat exchanger module 2B as schematically illustrated in Fig. 12. The third port 12A and the fourth port 16A of the first heat exchanger module form inlets/outlets for a first secondary flow channel 408, and the third port 12B and the fourth port 16B of the second heat exchanger module form inlets/outlets for a second secondary flow channel 410. In this embodiment, a first medium in the main flow channel exchanges heat with a second medium in the first secondary flow channel in the first heat exchanger module and exchanges heat with a third medium in the second secondary flow channel in the second heat exchanger module.

First medium having a temperature TA enters the heat exchanger system 402 at A
through the first port 4A, passes through the heat exchanger system and leaves the system through the first port 4B at B having a temperature TB. Second medium having a temperature Tc enters the heat exchanger system at C through the third port 12A, passes through the heat exchanger system and leaves the system through the fourth port 16A at D having a temperature TD. Third medium having a temperature TF
enters the heat exchanger system at F through the fourth port 16B, passes through the heat exchanger system and leaves the system through the third port 12B at E having a temperature TE.

The number of heat exchanger modules may be decided according to desired amount of heat to be transferred, and the modules may be connected depending on e.g.
number and temperature of media to be heat exchanged, operating pressure, etc.
Fig. 19 illustrates an exemplary projecting member. The projecting member 500 is formed as a circular segment constituted by the part between a chord 502 (second edge) and an arc 504 (first edge) of a circle, excluding the center of the circle. The length of the second edge 502 may be in the range from about 2 cm to about 30 cm, depending on the proportions of the flow channel and the media flowing in the flow channel, e.g. about 13 cm. The width D, may be in the range from about 0.5 cm to about 10 cm, e.g. 3.6 cm corresponding to half the width of the flow channels in the heat exchanger module.

In specific embodiments, the invention relates to the following items:

1. A heat exchanger module having walls defining flow channels and comprising a first flow channel having one or more first sections extending along a first axis and positioned in thermal contact with a second flow channel having one or more second sections extending along the first axis for heat exchange between a first medium flowing in the first flow channel and a second medium flowing in the second flow channel, wherein the heat exchanger module comprises a first projecting member attached to a wall and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the first projecting member.
2. A heat exchanger module according to item 1, wherein the heat exchanger module comprises a plurality of first projecting members attached to one or more walls and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the plurality of first projecting members.

3. A heat exchanger module according to any of items 1-2, wherein the first projecting member(s) is/are substantially plane.

4. A heat exchanger module according to any of the items 1-3, wherein the first projecting member(s) is/are substantially perpendicular to the wall to which it/they are attached.

5. A heat exchanger module according to any of the items 1-4, wherein the first projecting member(s) forms/form an angle with the first axis, the angle being less than 70 , such as from about 5 to about 60 , preferably from about 15 to about 45 .

6. A heat exchanger module according to item 5, wherein the first projecting member(s) forms/form an angle with the first axis from about 20 to about 30 .

7. A heat exchanger module according to any of the items 1-6, wherein the first projecting member(s) has/have a curved edge such that dry matter or other objects in the first medium are prevented from being caught by the first projecting member(s) and eventually blocking or narrowing the first flow channel.

8. A heat exchanger module according to item 7, wherein the first projecting member(s) has/have a semi-oval shape.

9. A heat exchanger module according to any of the items 1-8, wherein the heat exchanger module further comprises a second projecting member attached to a wall and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the second projecting member.

10. A heat exchanger module according to item 9, wherein the heat exchanger module comprises a plurality of second projecting members attached to one or more walls and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the plurality of second projecting members.

11. A heat exchanger module according to any of the items 9-10, wherein the second projecting member(s) is/are substantially plane.

12. A heat exchanger module according to any of the items 9-11, wherein the second projecting member(s) is/are substantially perpendicular to the wall to which it/they are attached.

13. A heat exchanger module according to any of the items 9-12, wherein the second projecting member(s) forms/form an angle with the first axis, the angle being less than 70 , such as from about 5 to about 60 , preferably from about 15 to about 45 .

14. A heat exchanger module according to item 13, wherein the second projecting member(s) forms/form an angle with the first axis from about 20 to about 30 .

15. A heat exchanger module according to any of the items 9-14, wherein the second projecting member(s) has/have a curved edge such that dry matter or other objects in the second medium are prevented from being caught by the second projecting member(s) and eventually blocking or narrowing the second flow channel.

16. A heat exchanger module according to item 15, wherein the second projecting member(s) has/have a semi-oval shape.

17. A heat exchanger module according to any of the items 1-16, wherein the heat exchanger module comprises a plurality of first sections and at least one first connector connecting first sections of the first flow channel.

18. A heat exchanger system comprising one or more heat exchanger modules according to any of the items 1-17.

19. A heat exchanger system according to item 18, wherein the heat exchanger system comprises a first heat exchanger module and a second heat module that are interconnected by one or more module connectors, such as fittings.

Claims

1. A heat exchanger module having walls defining flow channels and comprising a first flow channel having one or more first sections extending along a first axis and positioned in thermal contact with a second flow channel having one or more second sections extending along the first axis for heat exchange between a first medium flowing in the first flow channel and a second medium flowing in the second flow channel, wherein the heat exchanger module comprises a first projecting member attached to a wall and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the first projecting member, and wherein the first projecting member has a curved edge such that dry matter or other objects in the first medium are prevented from being caught by the first projecting member and eventually blocking or narrowing the first flow channel.

2. A heat exchanger module according to claim 1, wherein the heat exchanger module comprises a plurality of first projecting members attached to one or more walls and extending into the first flow channel, such that first medium flowing in the first flow channel is redirected when passing the plurality of first projecting members, and wherein the plurality of first projecting members has a curved edge such that dry matter or other objects in the first medium are prevented from being caught by the first projecting member and eventually blocking or narrowing the first flow channel.

3. A heat exchanger module according to any of claims 1-2, wherein the first projecting member(s) is/are substantially plane.

4. A heat exchanger module according to any of the preceding claims, wherein the first projecting member(s) is/are substantially perpendicular to the wall to which it/they are attached.

5. A heat exchanger module according to any of the preceding claims, wherein the first projecting member(s) forms/form an angle with the first axis, the angle being less than 70°.

6. A heat exchanger module according to any of the preceding claims, wherein the first projecting member(s) has/have a semi-oval shape.

7. A heat exchanger module according to any of the preceding claims, wherein the heat exchanger module further comprises a second projecting member attached to a wall and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the second projecting member.

8. A heat exchanger module according to claim 7, wherein the heat exchanger module comprises a plurality of second projecting members attached to one or more walls and extending into the second flow channel, such that second medium flowing in the second flow channel is redirected when passing the plurality of second projecting members.

9. A heat exchanger module according to any of the claims 7-8, wherein the second projecting member(s) is/are substantially plane.

10. A heat exchanger module according to any of the claims 7-9, wherein the second projecting member(s) is/are substantially perpendicular to the wall to which it/they are attached.

11. A heat exchanger module according to any of the claims 7-10, wherein the second projecting member(s) forms/form an angle with the first axis, the angle being less than 70°.

12. A heat exchanger module according to any of the claims 7-11, wherein the second projecting member(s) has/have a curved edge such that dry matter or other objects in the second medium are prevented from being caught by the second projecting member(s) and eventually blocking or narrowing the second flow channel.

13. A heat exchanger module according to claim 12, wherein the second projecting member(s) has/have a semi-oval shape.

14. A heat exchanger module according to any of the preceding claims, wherein the heat exchanger module comprises a plurality of first sections and at least one first connector connecting first sections of the first flow channel.

15. A heat exchanger system comprising one or more heat exchanger modules according to any of the preceding claims.

16. A heat exchanger system according to claim 15, wherein the heat exchanger system comprises a first heat exchanger module and a second heat module that are interconnected by one or more module connectors, such as fittings.