FI20195350A1 - A heat transfer system - Google Patents

Abstract

An invention relates to a heat transfer system (100, 200) having a flow passage for transferring heat by fluid. Said heat transfer system comprises a first member (110) having a first portion of a flow passage (131) inside thereof, having a first inlet (112) and a first outlet (113), and a variable cross section along it, between said first inlet (112) and first outlet (113); a second member (120) having a second portion of a flow passage (132) inside thereof, having a second inlet (122) and a second outlet (123), and a plurality of lamellas (121) arranged within it, between said second inlet (122) and second outlet (123). The invention relates also to an arrangement having a heat transfer system.

Description

A heat transfer system

Technical field

The present invention relates to a heat transfer system and an arrangement having a heat transfer system.

Background

The general function of a heat transfer system is to transfer heat from one fluid to another. The basic component of a heat transfer system can be viewed as a tube with one fluid running through it and another fluid flowing by on the outside. Such known heat transfer systems may be used in both cooling and heating processes.

One known example of a heat transfer system is a combustion engine in which a circulating fluid flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another know example is the heat sink, which is a passive heat transfer system that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.

Although heat transfer systems may appear structurally simple, the flow of fluid through it and the thermal connection between it and the surrounding fluid create a rather complicated problem.

Summary of the invention oO > An objective of this invention is to provide a heat transfer system by means of x which a heat transfer fluid is effectively transferred. 2

I 30 A further objective of this invention is to provide an arrangement for transferring > heat between a heat transfer system and a heat source. 3 o It is a further object of this invention to provide a modular heat transfer system.

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An object of the invention is further to improve or at least alleviate the disadvantages associated with previously known heat transfer solutions.

Objects of the invention are achieved by a heat transfer system having a flow passage for transferring heat by fluid. Said system comprises: a first member having a first portion of a flow passage inside thereof, having a first inlet and a first outlet, and a variable cross section along it, between said first inlet and first outlet, and a second member having a second portion of a flow passage inside thereof, having a second inlet and a second outlet, and a plurality of lamellas arranged within it, between said second inlet and second outlet.

Objects of the invention are further achieved by an arrangement having a flow passage for transferring heat by fluid. Said heat transfer arrangement comprises a heat source, and a heat transfer system, as presented above, which heat transfer system further comprises a first member having a first portion of a flow passage inside thereof, having a first inlet and a first outlet, and a variable cross section along it, between said first inlet and first outlet, and a second member having a second portion of a flow passage inside thereof, having a second inlet and a second outlet, and a plurality of lamellas arranged within it, between said second inlet and second outlet, wherein said heat source is configured to be in thermal connection with a heat transfer system formed of a first member and a second member.

One advantage of the invention is effective heat transfer compared to known heat transfer systems. A further advantage of the invention is the applicability of the heat transfer system in a wide variety of applications. A further advantage of the o invention is the modularity of the system, which further allows the use of different > heat sinks in the heat transfer system according to the invention. 3

O Preferred embodiments of the invention are presented in the dependent claims.

I 30 > Brief description of the drawings > The invention will now be described in more detail with reference to the preferred

N embodiments and with reference to the accompanying drawings in which:

FIGURE 1a is a side view of a heat transfer system according to an embodiment of the present invention;

FIGURE 1b is a cross-sectional side view of a heat transfer system according to an embodiment of the present invention;

FIGURE 2a is a side view of a first member of a heat transfer system according to an embodiment of the present invention;

FIGURE 2b is a cross-sectional side view of a first member of a heat transfer system according to an embodiment of the present invention;

FIGURE 3a is a side view of a second member of a heat transfer system according to an embodiment of the present invention;

FIGURE 3b is a cross-sectional front view of a second member of a heat transfer system according to an embodiment of the present invention;

FIGURE 4 is a cross-sectional front view of a second member of a heat transfer system according to an alternative embodiment of the present invention;

FIGURE 5a is a side view of a heat transfer system according to an alternative embodiment of the present invention; o FIGURE 5b is a cross-sectional side view of a heat transfer system according to an > alternative embodiment of the present invention. 3 > Detailed description of the embodiments

I 30 > Embodiments of according to an invention are shown in FIGS. 1-5. o FIG. 1a shows a side view of a heat transfer system according to an embodiment of

N the present invention. FIG. 1b shows a cross-sectional side view of a heat transfer system shown in FIG. 1a. A heat transfer system 100 according to embodiment comprises a first member 110, which is a tube of any cross-sectional shape, having a varying cross section along it, and a second member 120, which is another tube of any cross-sectional shape, such as cylindrical or rectangular tube, which said first member 110 and second member 120 are attached to each other, either permanently or detachably, for example by welding. Also, other attachment methods may be used, such as, screws, bolts, nuts, bands, quick coupling means and flanges.

Said heat transfer system 100 is connected to an arrangement having a heat source 300, which may be, for example, an electronic or mechanical device, any process that produces heat, a machine or a system. The heat source 300 may be, for example, a circuit board, a processor, an electromagnetic device, a semiconductor component such as a diode, a light emitting diode or a transistor. The heat source 300 is arranged in thermal connection with a heat transfer system 100 so that the heat produced by a heat source 300 can be transferred from a heat source 300 to a heat transfer system 100 and vice versa from a heat transfer system to a heat source. In a heat transfer system 100, there may be a fastening plate, a heat plate or an element to which said heat source is mounted, through which the heat produced by a heat source is transferred to a heat transfer system.

In a heat transfer system 100, there is an inlet opening 112 at one end of a first member 110 and an outlet opening 123 at one end of a second member 120, as well as walls 119, 129 of the tubes of members 110, 120 extending between said inlet 112 and outlet 123 defining a flow passage 131-132 inside said tubes 110, 120 which flow passage 131-132 guides the fluid flow that enters to said heat transfer o system 100 from an inlet 112 and which is further transferred towards an outlet 123 > through said members 110, 120 at a given flow rate. The purpose of a first member x 110 is to act as a fluid flow regulator, regulating fluid flow through a first portion of

S flow passage 131 of a first member 110, and transferring it to a second portion of

I 30 flow passage 132 of a second member 120. Said first member 110 regulates both > the fluid flow rate and the heat transfer from a second member 120. The purpose of

D a second member 120 is to act as a heat sink, whereby it receives heat from a first 3 member 110 and conducts the received heat away from the system to the

N environment.

FIG. 2a shows a side view of a first member of a heat transfer system according to an embodiment of the present invention. FIG. 2b shows a cross-sectional side view of a first member shown in FIG. 2a. A first member 110 comprises a first portion of a flow passage 131 of heat transfer system, which flow passage is arranged inside a 5 first member. The first portion of the flow passage 131 has a first inlet 112 and a first outlet 113, as well as inner walls 119 extending between said first inlet and first outlet and defining said flow passage 131 having a variable cross section extending along said first portion between said first inlet 112 and first outlet 113.

Said first inlet and first outlet of a first member 110 may be provided with flanges (not shown) having an opening of any shape, such as circular or rectangular but not limited thereto, which is concentric with the flow passage of the first portion. The flanges are preferably arranged in a direction perpendicular to the direction of flow.

The flanges may be further provided with attachment means, such as bolt or nuts.

However, the flanges are not the only option for attachment. Instead of flanges, other types of attaching may also be used, such as, for example, a band, and a compression joint or welding. In FIG. 2b, the flow direction is indicated by arrows from a first inlet 112 to a first outlet 113.

A first member 110 is preferably shaped to have a variable cross section along the length of the flow passage inside thereof. It can be formed from a plurality of discrete portions which together form a single separate part. According to an embodiment, a first member 110 may comprise a conical contracting portion 116, a cylindrical choke portion 117 and a conical expanding portion 118. In addition to portions 116-118, a first member 110 may further comprise an inlet tube portion o 115, as shown in FIGS. 5a and 5b. Said portions 116-118 or 115-118 may be > attached to each other, for example, by welding said portions together. Also, other x attachment methods may also be used, such as, for example, a band, flanges or a

S compression joint. Each portion may have a certain length and a diameter and need

I 30 not necessarily be the same size. In addition, although the foregoing refers to a > conical or cylindrical shape in connection with portions 115-118, the cross-sectional

E shapes of said portions 115-118 may also be of any other shape, for example, o cylindrical, rectangular or polygonal, such as, pentagonal or hexagonal. However,

N the design of said portions 115-118 should follow the instructions given later in the following paragraphs.

A first member 110 may be made of different materials, depending on the purpose of heat transfer application for which it is used. Such materials may be, for example, steel, copper, aluminum, graphite or ceramic material. A first member 110 may also be made as a structure in which it is divided into two or more parts, which can be manufactured separately. Thus, for example, an inlet tube portion 115 and conical contracting portion 116 may form a first separate sub-assembly and a cylindrical choke portion 117 and a conical expanding portion 118 may form a second separate sub-assembly. The sub-assemblies can be attached to each other in the same manner as said portions 115-118, for example, with flanges, bands, compression joints, or welding.

According an embodiment a first member 110 of a heat transfer system may be a

Venturi tube, a tube having a varying diameter. In a heat transfer system with a

Venturi tube, the operation principle is as follows. When the fluid comes in to a heat transfer system via a first inlet 112 of a first member 110 and it reaches a cylindrical choke portion 117 of a first member 110, the cross-sectional area decreases, and the fluid flow is choked and fluid flow reaches speed of very high velocity. When a fluid is in a state of choked flow, a decrease in the downstream pressure environment will not lead to an increase in the flow rate. However, flow rate for a compressible fluid will increase with increased upstream pressure, which will increase the density of the fluid through the constriction. The effect of Venturi, as explained above, is a well-known Bernoulli statutory phenomenon in which the velocity of the flowing fluid increases, and the pressure decreases as fluid passes through a narrowed tube of a cylindrical choke portion 117. Since the volume flow rate of the fluid must remain constant, the flow rate increases as the tube narrows, o as a result of the continuity eguation. When the fluid flow rate increases as the tube > narrows, the fluid-induced pressure is reduced. Thereby, to achieve above Venturi x effect in a first member 110 of a heat transfer system, the diameter d of the

S cylindrical choke portion 117 must be egual to the length of the cylindrical choke

I 30 portion. The angle of a conical contracting portion 116 may therefore be, for > example, in the range of 20-30 degrees but may vary. In addition, the angle of a

E conical expanding portion 118 may be, for example, in the range of 5-15 degrees

O but may vary.

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In addition to a Venturi tube, it is possible to use other solutions in the embodiments. The following are examples of the embodiments for designing a first member 110 as an alternative for a Venturi tube. In the embodiments, said choke portion 117 may be cylindrical preferably having a diameter equal to its length d.

However, as previously stated, the cross-sectional shape of a first portion 110 need not be cylindrical or conical, but other cross-sectional shapes may also be possible.

In addition, in contrast to the Venturi tube, the conical contracting portion and the conical expanding portion may be of equal length and width and of equal diameter.

For example in case of cylindrical shape, if a diameter of a cylindrical choke portion is 100 mm, its length may be 100 mm. The lengths of a conical contracting portion 116 and a conical expanding portion 118 may be of the same length, but may also vary. Also, the angles of a conical contracting portion 116 and a conical expanding portion 118 may vary. For example, if the diameter of the conical contracting portion 116 on the inlet cylinder side is, for example, 160 mm and the diameter of — the cylindrical choke portion is 100 mm, the length of said conical contracting portion may be, for example, 40 mm. For example, if the diameter of the conical expanding portion 118 on the side of a second member 120 is, for example, 160 mm and the diameter of the cylindrical choke portion is 100 mm, the length of said conical expanding portion 118 is, for example, 40 mm.

In the above example, in a heat transfer system, the operation is then as follows. As the fluid enters an inlet 112 in the longitudinal direction of a first member 110 toward a second member 120, the fluid suction is improved when it reaches the narrowed tube portion within a first member. In the narrow center, the speed of fluid increases, whereby the heat transfer system "pumps" heat more efficiently out o of a heat source 300. After a first member, the fluid as it flows towards a second > portion 120 slows down and the temperature drops, whereby heat is transferred x along the lamellae from the inside of the tube of a second member 120 to outside

S of a second member.

I 30 > FIG. 3a shows a side view of a second member of a heat transfer system according

D to an embodiment of the present invention. FIG. 3b shows a cross-sectional front 3 view of a second member shown in FIG. 3a. As mentioned above, said second

NN member 120 act as a heat sink. It comprises a second portion of a flow passage 132 of a heat transfer system inside thereof which is defined by a second inlet 122 and a second outlet 123 and the walls 129 of a second member 120 extending between said second inlet 122 and second outlet 123. Said second inlet and second outlet of a second member 120 may further be provided with flanges having an opening of any shape, such as circular or rectangular but not limited thereto, which is concentric with a flow passage 132 of a second portion. The flanges in a second member 120 are preferably arranged in a direction perpendicular to the flow direction. The flanges of a second portion may further be provided with attachment means at the edges of the flanges. In addition to flanges, also other types of attaching may be used, such as, for example, a band, and a compression joint or welding. In FIG. 3a, the flow direction is indicated by arrows from a second inlet 122 to a second outlet 123.

A second member, a heat sink, may be provided with a plurality of lamellae 121, for example thin plates arranged therein. Said lamellae 121 are arranged on the wall of a second member 120 around it between said second inlet 122 and second outlet 123. Each lamella 121 arranged in a second member 120 may include a specific mechanical structure which may be designed and dimensioned based on the heat transfer application. Said structures of lamellas may include for example, pins, straight lamellas, solid rods, tubes or flame lamellas. The shape of lamellas can be, for example, elliptical, cylindrical, grid-like or square. There may be several ways of producing the lamellae, for example, extrusion, welding, laser welding, soldering, gluing, bonding, die casting, forging, machining and compressing. As materials for lamellas, heat-conducting materials, for example, copper, aluminum, steel, thermally conductive plastic, graphite, tin or some their alloys can be used. o In an embodiment a plurality of lamellas 121 are arranged to extend from the inside > of a flow passage 132 to outside of a flow passage so that at least one portion of x each lamella is in the flow passage 132, and at least one other portion is outside the

S flow passage. In an embodiment, the a plurality of lamellas 121 are arranged in the

I 30 flow passage 132 so that they are spaced apart and are not in contact with each > other in the flow passage, as shown in FIG. 3b. In another embodiment shown in

E Figure 4, a plurality of lamellas 121 are arranged in the flow passage 132 so that

O they are in contact with each other in the flow passage. Each of a plurality of

N lamellae 121 can further extend along the flow passage 132 in the direction of the fluid flow, so that each lamella 121 can be simultaneously in contact with both the fluid to be transferred in a flow passage 132 of a second portion and the environment outside a heat sink. The length of each lamella 121 in the flow direction can be, for example, equal to or less than the length of a flow passage in the flow direction.

The purpose of lamellae 121 is to increase surface area of a heat sink and therefore increase heat transfer efficiency between fluids. When a lamella 121 is exposed to a flowing fluid, which cools or heats it, with the high thermal conductivity of the lamellae, it allows increased heat being conducted from a heat source through said lamellae 121. The use of lamellas also makes it possible to transfer heat at a desired point in a second member. For example, in heat transfer applications where there are other devices in connection with the heat transfer system 100, such as fans that are around a second member 120, it may be advantageous to transfer the heat to the locations where other devices are located to enhance heat transfer from the heat transfer system 100. For example, if a fan or blower is provided outside the heat sink, a second member, said lamellae 121 allow more efficient heat transfer from fluid to the fan flow than without lamellae.

In addition to the foregoing, it may be possible to configure, or manufacture, a plurality of lamellae into different entities, or sub-assemblies, so that it is possible to arrange a plurality of lamella assemblies into the flow passage in a flow direction successively. In addition, the various lamella assemblies may be located at different angles to each other, whereby the flow of fluid encounters them at different points in the flow passage. In FIG. 3b is a cross-sectional view of a second member seen from the front end. In this embodiment, a plurality of lamellae is arranged in a flow o passage so that each lamella is separated from each other whereby said lamellas do > not contact with each other. FIG. 4 shows an alternative embodiment of a second x member 120" in which the lamellae 121’ are connected to each other at their flow

S passage side ends.

I 30 > A second member 120 may be made of different materials, for example steel,

D plastic, ceramic or graphite. It can be made of a material different from that of a 3 plurality of lamellas 121. In addition, it can be made of a material different from

N that of a first member 110. In an embodiment, a second member, a heat sink, is formed of a plurality of concentric tubes arranged in one another. This embodiment is shown in FIG. 4. The shape is designed so that the tubes 133 are concentrically nested, and adjacent tubes may be spaced apart so that there may be a gap or space between them. The nested tubes may be of the same length, or of different lengths. Each tube may have a function. For example, some fluids transferred may require acid-resistant steel, whereby the material of the tube must be selected accordingly, while in some other cases, it may be advantageous to use materials with high thermal conductivity, such as copper or aluminum, for example. Various fluids, such as gas or liquid, or materials, may be provided between adjacent nested tubes of a second member. For example, there may be porous graphite or phase change material between the tubes to improve the heat transfer between the tubes.

For example, when using phase change material, this may be in a stationary or non- stationary state. The space between the two adjacent tubes may be arranged to be closed at the ends of the space between said adjacent tubes, whereby the walls of the adjacent tubes and ends of the tubes limit the closed compartment to the phase change material between the tubes. Alternatively, the ends between adjacent tubes may be open. The inner surface of said tubes and/or the outer surface may also be coated with a coating. For example, the coating may be selected from the group consisting of epoxy, titanium dioxide, Teflon, thermochromic materials, graphite or diamond-like carbon (DLC). In addition to the tube, each of the lamellas can also be coated. The coating may have different purposes. One purpose of the coating material may be to act as a catalyst. Coating can also act as an indicator, such as when using thermochromic materials. The coating may improve fluid flow properties, improve friction properties, wear resistance, and prevent adhesion such as DLC. The coating can also be used to improve the heat transfer of properties such as graphite coating. oO > FIG. 5a shows a side view of a heat transfer system according to an alternative x embodiment of the present invention. FIG. 5b shows a cross-sectional side view of a

S heat transfer system shown in FIG. 5a. If FIGS. 1a and 1b are compared with FIGS.

I 30 5a and 5b, it will be noted that the embodiments shown in FIGS. 5a and 5b have an > elongated inlet tube section 115 at the inlet end of a heat transfer system 200. The

D tube section is designed to direct the fluid to the heat transfer system at the desired 3 angle. The tube may be straight or curved, or bent at certain angle, for example. It

NN can be of any cross-sectional shape. In addition, it can be an integral part of a heat transfer system 200, or a retrofit part.

In addition to the above-mentioned embodiments, both a first member 110 and a second member 120 may also be provided with a plurality of measuring points arranged in their walls, e.g. the measuring points are preferably located in an inlet cylinder, in an additional outlet cylinder or in a cylindrical choke portion. The measurement data collected from the measuring points allow, for example, the implementation of a return control system for control devices connected to the heat transfer system, such as separate fans or control systems.

Even though the invention has been described above with reference to examples according to the accompanying drawings, the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims.

Therefore, all words and expressions should be interpreted broadly, and they are intended to illustrate, not to restrict, the embodiment.

It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways. o

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Claims (15)

Claims

1. A heat transfer system (100, 200) having a flow passage for transferring heat by fluid, characterized in that said heat transfer system comprises: a first member (110) having a first portion of a flow passage (131) inside thereof, having a first inlet (112) and a first outlet (113), and a variable cross section along it, between said first inlet (112) and first outlet (113); a second member (120) having a second portion of a flow passage (132) inside thereof, having a second inlet (122) and a second outlet (123), and a plurality of lamellas (121) arranged within it, between said second inlet (122) and second outlet (123).

2. A heat transfer system (100, 200) according to claim 1, characterized in that a first member (110) comprises an inlet cylinder, a conical contraction portion (116), a cylindrical choke portion (117) and a conical expanding portion (118) connected to each other.

3. A heat transfer system (100, 200) according to claim 1, characterized in that a plurality of lamellas (121) are arranged to extend from the inside of a flow passage (132) to outside of a flow passage.

4. A heat transfer system (100, 200) according to claim 1, characterized in that a plurality of lamellas (121) is arranged in contact with each other within a flow passage. 2

N 5. Aheattransfer system (100, 200) according to claim 1, characterized in that S a plurality of lamellas (121) is made of a material different from that of a second a 30 — member (120). =

> 6. A heat transfer system (100, 200) according to claim 1, characterized in that A a plurality of lamellas (121) are arranged to extend along said second member D (120) between said second inlet (122) and second outlet (123). N 35

7. A heat transfer system (100, 200) according to claim 1, characterized in that a plurality of lamellas (121) is provided with a coating.

8. A heat transfer system (100, 200) according to claim 1, characterized in that a first member (110) is a Venturi tube.

9. A heat transfer system (100, 200) according to claim 1, characterized in that a second member (120) is a heat sink.

10. A heat transfer system (100, 200) according to claim 1, characterized in that a second member is provided with a coating.

11. A heat transfer system (100, 200) according to claim 1, characterized in that a second member is formed of a plurality of concentric tubes arranged in one another.

12. A heat transfer system (100, 200) according to claim 1, characterized in that a second member is provided with a phase change material.

13. A heat transfer system (100, 200) according to claim 1, characterized in that a first member (110) is made of a material different from that of a second member (120).

14. A heat transfer system (100, 200) element according to claim 1, characterized in that a second member (120) is detachably arranged in a first member (110).

15. An arrangement having a flow passage for transferring heat by fluid, characterized in that, the arrangement comprising: © a heat source (300); & 30 S a first member (110) having a first portion of a flow passage (131) inside thereof, 3 having a first inlet and a first outlet, and a variable cross section along it, between z said first inlet and first outlet; a D 2 35 asecond member (120) having a second portion of a flow passage (132) inside 2 thereof, having a second inlet and a second outlet, and a plurality of lamellas N arranged within it, between said second inlet and second outlet.

wherein said heat source (300) is configured to be in thermal connection with a heat transfer system formed of a first member (110) and a second member (120). o O N <+ <Q O 0 I jami a O LO 0 LO o Oo N