WO2003027553A2

WO2003027553A2 - A system for controlling the flow rate of a fluid

Info

Publication number: WO2003027553A2
Application number: PCT/DK2002/000759
Authority: WO
Inventors: Martin Peter Engholm
Original assignee: Rigshospitalet
Priority date: 2001-11-16
Filing date: 2002-11-14
Publication date: 2003-04-03
Also published as: WO2003027553A3; AU2002351716A1

Abstract

The present invention relates to a system that automatically increases or decreases flow in tubes when exposed to temperature variations and to a tube that automatically stops fluid from flowing when exposed to heat. The system comprises a plurality of members at least one of the members being an element arranged inside a tube, thus definig a longitudinally extending flow channel between the element and the tube. The element and the tube have different thermomechanical properties, so that the cross-sectional-area of the flow channel varies when the system is exposed to temperature variations.

Description

A SYSTEM FOR CONTROLLING THE FLOW RATE OF A FLUID

The present invention relates to a system that automatically increases or decreases flow in tubes when exposed to temperature variations and to a tube that automatically stops fluid from flowing when exposed to heat.

Background of the invention

Currently known systems for controlling the flow in tubes comprises components, which are complex in structure and complex to produce. The structure of the flow regulating systems comprises organs for increasing and decreasing flow in the tube by moving a valve. The movement of the valve is controlled by a mechanism that responds to the temperature measured in a specific point. The mechanism is normally a closed-loop control system. The whole system comprises several components of which some are able to move following a predefined path. To have the right operation of the mechanism components must be assembled in a specific order and with accuracy. Assembly of the system is therefor time consuming and complex.

EP 0 334 556 Al describes an invention that cuts off fuel feed to an engine of a vehicle. The fuel is cut off by coating the inside of a fuel tube with a foaming agent which foams inwards when exposed to heat. The fuel flows inside the coated tube.

Description of the invention

It is an object of the invention to provide a simple mechanism with few components that can automatically increase or decrease flow in tubes when exposed to temperature.

It is a further object of the invention that the few components used are cheaply produced from known materials, which needs little processing and assembly.

It is a further object of the invention to provide a mechanism where the measurement of the temperature that regulates the flow is done at any point of the tube.

It is a further object of the invention to provide a mechanism where the mechanism can regulate the flow at any point of the tube.

Definitions and explanations relevant to some of the terms used in the present specification and claims are as follows: "Inflammable fluid " means fluid such as diesel, petrol, gas, kerosine, alcohol or a mix of these. Inflammable fluids are used e.g. for combustion engines, thinner for paint production. Examples are numerous and includes any distilled product of crude oil such as kerosine, gasoline, diesel etc.

"Hydraulic diameter" means the cross-sectional-area of a an member divided by the circumference of the member,

"Hydraulic flow diameter" means the hydraulic diameter of an outer member surrounding an inner member, divided by the hydraulic diameter of the inner member.

Thus, the present invention provides a system for controlling the flow rate of a fluid, comprising a plurality of members: - At least one of the members being an element arranged inside at least one member being a tube, defining at least one longitudinally extending flow channel between a first and a second of the members of the system, the at least one element and at the at least one tube having different thermo mechanical properties, so that the cross-sectional-area of the at least one flow channel varies when the system is exposed to temperature variations.

The system comprises a plurality of members, the members comprising elements and tubes. In a preferred embodiment of the invention the system comprises an element placed inside at least one tube. The element may be a rod placed inside the at least one tube. The rod and the tube are co-extending in the longitudinal direction, thus defining a longitudinal flow channel between the rod and the tube. If the rod is placed inside more tubes a longitudinal flow channel may also be defined between the tubes. Fluid may flow inside at least one flow channel of the system. The fluid may be an inflammable fluid and thus the system may e.g. be used to supply a combustion engine with fuel.

The members of the system have different thermo mechanical properties so that e.g. some members may expand faster than other members when exposed to temperature variations. This principle is used in the invention to regulate flow in the at least one flow channel. The principle could e.g. be used in chemical processes for regulating flow in flow channels.

The members of the system may be placed inside each other without being connected to each other but may also be attached to each other or contain other arrangements that position a first member in relation to a second member. As an example an element placed inside a tube may comprise a spring-arrangement which positions the element in relation to the tube. In an alternative embodiment an element of the system may comprise strips extending e.g. perpendicular from the element. The strips are then integrated in a tube surrounding the element thus positioning the element in relation to the tube.

By using the thermo mechanical properties of the tubes as a means for regulating the flow the system responds to temperature variations at any point at the tubes. This may be used to regulate flow at any point of the tube e.g. by applying frigidity locally so that the flow channel e.g. is narrowed in. In an alternative embodiment of the invention the temperature of the fluid flowing in the flow channel is used to regulate the flow rate. In such an embodiment the temperature of the fluid may e.g. be raised e.g. resulting in an increased flow channel.

The system that automatically increases or decreases flow in flow channels when exposed to temperature variations may be used for fire fighting purposes. In this situation the cross-sectional-area of the at least one flow channel increases when the system is exposed to heat resulting in an increased flow of the fire fighting fluid. This mechanism may be realised by using members with different thermo mechanical properties so that e.g. a tube expands more than the element placed inside it, thus resulting in an increased cross sectional area of the flow channel. As an example this embodiment of the invention may also be used in greenhouses for watering of plants but may also be used for watering animals so that the water supply increases when the temperature is increased. Furthermore the invention may be used for temperature regulating purposes so that the system works as a thermostat. The user of the system may then cover the system with a temperature insulating mechanism resulting in an increased or decreased supply of the heating or cooling fluid flowing in the flow channel.

The system that automatically increases or decreases flow in flow channels when exposed to temperature variations may be used for heating purposes. In this situation the cross- sectional-area of the at least one flow channel increases when the system is exposed to frigidity. The result is an increase in flow of the fluid used to heat an environment such as a room. The fluid can be an inflammable fluid and thus the increased supply results in an increased combustion and generation of heat. This mechanism may be realised by using members with different thermo mechanical properties so that e.g. an element contracts more than the tube it is placed inside when exposed to frigidity, thus resulting in an increased flow channel.

The system that automatically increases or decreases flow in flow channels when exposed to temperature variations may be used for fuel supply purposes. In this situation the cross- sectional-area of the at least one flow channel decreases when the system is exposed to heat so as to reduce fluid flow through said channel. The advantage of a system in this embodiment is that in the case of a fire near the fuel supply system, e.g. connected to a combustion engine, the supply of fuel will be limited and even stopped. In systems where fuel supply is not limited or stopped there is the risk that additional supply of fuel will boost the fire thus increasing the danger and risk of explosions. This mechanism may be realised by using members with different thermo mechanical properties so that e.g. a tube contracts more than an element placed inside the tube when exposed to heat, thus resulting in an decreased cross sectional area of the flow channel.

The system that automatically increases or decreases flow rate in flow channels when exposed to temperature variations may be used for limiting flow in a radiator system such as a radiator system used in connection with an engine. In this situation the cross- sectional-area of the at least one flow channel decreases when the system is exposed to frigidity so as to reduce fluid flow through said channel. By using the mechanism to connect the engine with the radiator it is possible to reduce flow in the radiator until the engine reaches a desired temperature level. This mechanism may be realised by using members with different thermo mechanical properties so that e.g. a tube contracts more than an element placed inside the tube when exposed to frigidity, thus resulting in an decreased flow channel.

Furthermore the system may be used in tube systems carrying a fluid e.g. water which freezes when exposed to temperatures below e.g. 0 degrees Celsius. The advantage of the invention in this embodiment is that the tube system displaces the fluid from areas where the temperature is below the freezing point, thus eliminating damage caused by the low temperature. As an example this could be a burst in a water pipe resulting in water damage when the temperature is high enough to make water flow again.

The members of the system may be made of a material comprising at least one metal and/or at least one alloy such as iron, steel, brass, gold, silver, zinc, aluminium, magnesium, titanium, copper, nickel, lead and/or platinum. Thus the members may e.g. be made of 100% iron but could also be made of a rubber material comprising pieces of iron.

In a preferred embodiment of the invention the cross-sectional-area of a flow channel is reduced when the system is exposed to heat or frigidity so as to prevent fluid from flowing through said channel. As said above the advantage of this embodiment can be that the system can be used for limiting freezing damage or supply of fuel to a combustion engine on fire. Furthermore the system may contain at least one of the tube, which is made of a material that shrinks when exposed to heat. An example of such a material could be Heatshrink™ awaliable from the company Heatshrink.com™. The material shrinks irreversibly when exposed to heat thus tubes made of this material can be used for stopping fuel supply to a burning area e.g. a burning combustion engine. An advantage of this material is that the Heatshrink™ can withstand high temperatures without cracking, thus preventing further leaks.

The material that shrinks may be produced in different embodiments so that it shrinks at different temperatures such as when exposed to temperatures above 80 degrees Celsius, such as above 100 degrees Celsius, such as above 110 degrees Celsius, such as above 120 degrees Celsius, such as above 130 degrees Celsius, such as above 140 degrees Celsius, such as above 150 degrees Celsius, such as above 175 degrees Celsius, such as above 200 degrees Celsius, such as above 225 degrees Celsius, such as above 250 degrees Celsius, such as above 275 degrees Celsius, such as above 300 degrees Celsius, such as above 325 degrees Celsius, such as above 350 degrees Celsius.

Furthermore the flow diameter of the at least one tube made from the material that shrinks when exposed to heat, may shrinks to 90 percent of the of the starting flow diameter of that tube. But could alternatively shrink to 80 percent, or 70 percent, or 60 percent, or 50 percent, or 40 percent, or 30 percent, or 20 percent, or 10 percent.

The hydraulic flow diameter of a flow channel defined by two members of the system, at least one of the members being made of a material that shrinks when exposed to heat, shrinks to between 0% and 100% of the hydraulic flow diameter before the system was exposed to heat, such as 90%, such as 80%, such as 70%, such as 60%, such as 50%, such as 40%, such as 30%, such as 20%, such as 10 %, such as 0%.

The at least one element of the system may be shaped in many different ways such as circular cylindrical shell or, half cylinder shell or, circular cylinder or, semi-cylinder or, elliptical cylinder or, cylinder with a polygonal cross section or, rectangular parallelepiped, spherical shell or, hemispherical shell or, sphere, hemisphere or, conical shell or, half conical shell or, cone or, half cone or, semi-ellipsoid or, elliptic paraboloid or, tetrahedron or, torus or three-dimensional-polygon. But the at least one element could also be formed as a rod having any shape of its cross-sectional-area.

In a preferred embodiment of the invention the members of the system are flexible in the longitudinal direction, thus making it possible to connect e.g. a fuel tank to an engine under circumstances where a direct connection is not possible. As an example this is useful in engine rooms where the architecture is compact thus making it necessary to use flexible elements.

In another embodiment of the invention the elements of the system are stiff in the longitudinal direction, thus making it possible e.g. to use the system as a constructive element capable of transferring forces and torque's. An additional advantage of stiff elements is that they can float in the air and still maintain a predefined shape.

To be able to construct at system where the cross-sectional-area of the at least one flow channel varies when the system is exposed to temperature variations the members of the system may have different thermo mechanical properties. Therefore the members may be made of a material having a thermal conductivity greater than 0,1, such as 0,2, such as 0,3, such as 0,5, such as 0,7, such as 1, such as 3, such as 5, such as 10, such as 13, such as 17, such as 20, such as 25, such as 30, such as 40, such as 50, such as 70, such as 100, such as 125, such as 150, such as 175, such as 200, such as 250, such as 300, such as 350, such as 400, such as 450.

In a preferred embodiment of the system the at least one element is segmented e.g. by comprising a plurality of members interconnected by a wire. The advantage of this embodiment is that it makes the system flexible while it is possible to decrease the flow channel thus limiting or preventing the fluid from flowing.

The system may be adapted for carrying an acid or a base. Thus the system may be used e.g. chemical production or in chemical laboratories. Further more the system may be adapted for carrying inflammable fluids, e.g. making it possible to use the system for supplying an engine with fuel or for fuel supply to heating mechanisms.

The at least one tube of the system may be irradiated, thus making it possible to shape the tube in an unstable geometry. The tube may then return to a stable geometry when exposed to heat, e.g. by shrinking. Furthermore the tube may be made of different materials able to be formed in an unstable geometry when irradiated. Such materials may be polyolefin or, poly-tetra-fluoro-ethylene or, poly-vinylidene-fluoπde or, fluoro-ethylene- propylene or, per-fluor-alkoxy or, ethylene-tetra-fluoro-ethylene-copolymer or, ethylene- chloro-tπ-fluoro-ethylene or, polyvinyl-fluoπde or, any other material being able to be formed to an unstable geometry when irradiated.

In a preferred embodiment the mechanism comprises an element and a tube surrounding the element. Between the tube and the element flows an inflammable fluid. The element is solid and made of a metal or an alloy such as iron, steel, brass, gold, silver, zinc, aluminium, magnesium, titanium, copper, nickel, lead and/or platinum. The tube is made of irradiated polyolefin such as Heatshrink™. The tube is characterised in that it shrinks when exposed to temperatures above 120 degrees Celsius. Depending on the quality of the irradiated polyolefin the tube shrinks so that the radius of the tube is reduced to between 20% and 50% of the radius of the same tube before exposure to heat. The radius of the element is equal to the radius of the tube after exposure to heat. As a result the flow between the two tubes is blocked when the system is exposed to heat, such as flames or radiation heat. Thereby inflammable fluid is not supplied to the fire.

Brief description of the figures

An embodiment of the invention will now be described in detail with reference to the drawings in which:

Fig. 1 shows an element arranged inside a tube,

Fig. 2 shows a segmented element arranged inside a tube,

Fig. 3 shows an element arranged inside a tube that shrinks when exposed to heat,

Fig. 4 shows an element arranged inside a tube which a decreased cross-sectional-area of the flow channel,

Fig. 5 shows an element arranged inside a tube which a increased cross-sectional-area of the flow channel,

Fig. 6 shows a system comprising a fuel tank, a motor and an element arranged inside a tube, and

Fig. 7 shows an experimental set-up used to test the invention.

Detailed description of the figures

Fig. 1 shows a system 12 for controlling the flow rate of a fluid. The system 12 comprising at least one element 11 arranged inside one tube 10, thus defining a longitudinal flow channel between the element 11 and the tube 10. The element 11 may be pulled out of the tube 10 for shortening, so that it is possible to mount the tube 10 to a connecting piece, which, when mounted, is placed partly inside the tube 10. Fig. 2 shows a system 24 for controlling the flow rate of a fluid. The system 24 comprises at least one segmented element 21 comprising a plurality of members 22 interconnected by a wire 23 or pieces of wire 23. The segmented element is arranged inside one tube 20, thus defining a longitudinal flow channel between the segmented element 21 and the tube 20. The system 24 may be produces in endless tubes 20 rolled up on coils. In this case the outside of the tube 20 may have indications of which part of the tube 20 that contains the elements 22 and which parts of the tube 20 that contains the wire 23. The indications makes it possible to cut the tube 20 where wire 23 is placed inside, which makes cutting of the endless tube easier. When the system 24 is cut in smaller pieces the segmented element 21 may be pulled out of the tube 20 for shortening, so that it is possible to mount the tube 20 to a connecting piece, which, when mounted, is placed partly inside the tube 20. The wire 23 may be cut with known wire-cutters, but the segmented element 21 may also be arranged so that it is possible to unhook the wire 23 form the elements 22.

Fig. 3 shows a system 32 for preventing fluid from flowing when exposed to heat 33. The system 32 comprises an element 31 arranged inside a tube 30, thus defining a longitudinal flow channel between the element 31 and the tube 30. When the system is exposed to heat 33 the tube 30 shrinks as shown in reference 30a and thus fluid is prevented from flowing.

Fig. 4 shows a system 42 for controlling the flow rate of a fluid. The system 42 comprising an element 41 arranged inside a tube 40, thus defining a longitudinal flow channel between the element 41 and the tube 40. The system 42 can be configured in two ways. One way is that the flow channel is reduced 40a when the system is exposed to heat. Another way is that the flow channel is reduced 40a when the system is exposed to frigidity.

Fig. 5 shows a system 52 for controlling the flow rate of a fluid. The system 52 comprising an element 51 arranged inside a tube 50, thus defining a longitudinal flow channel between the element 51 and the tube 50. The system 52 can be configured in two ways. One way is that the flow channel is increased 50a when the system is exposed to heat. Another way is that the flow channel is increased 50a when the system is exposed to frigidity.

As shown in Fig. 6, the system 64 for controlling the flow rate of a fluid comprising an element 61 arranged inside a tube 60, thus defining a longitudinal flow channel between the element 61 and the tube 60, can be connected to a fuel tank 63 and an engine 62. If a fire occurs in the engine 62 the supply of fuel is limited or prevented by the system 64, due to a reduced or prevented fuel supply. Fig. 7 shows an experimental set-up 74 used to test the invention. The set-up comprises an element 71 arranged inside a tube 70 thus defining a longitudinal flow channel between the element 71 and the tube 70. The tube is connected to a funnel 72 via a tap 73. During the test of the invention the funnel 72 was loaded with an inflammable fluid. The tap 73 was opened to insure flow of the inflammable fluid. Hereafter the part of the tube 70 surrounding the element 71 was exposed to heat. As a result the tube 70 shrunk a thus the inflammable fluid was prevented from flowing.

Claims

1. A system for controlling the flow rate of a fluid, comprising a plurality of members: At least one of the members being an element arranged inside at least one member

> being a tube, defining at least one longitudinally extending flow channel between a first and a second of the members of the system, the at least one element and at the at least one tube having different thermo mechanical properties, so that the cross-sectional-area of the at least one flow channel varies when the system is exposed to temperature variations.

2. A system according to claim 1, wherein the cross-sectional-area of the at least one flow channel increases when the system is exposed to heat so as to increase fluid flow through said channel(s).

3. A system according to claim 1, wherein the cross-sectional-area of the at least one flow channel increases when the system is exposed to frigidity so as to increase fluid flow through said channel(s).

4. A system according to claim 1, wherein the cross-sectional-area of the at least one flow channel decreases when the system is exposed to heat so as to reduce fluid flow through said channel(s).

5. A system according to claim 1, wherein the cross-sectional-area of the at least one flow channel decreases when the system is exposed to frigidity so as to reduce fluid flow through said channel(s).

6. A system according to claim 4-5, wherein the cross-sectional-area is reduced so as to prevent fluid from flowing through said channel(s).

7. A system according to claim 6, wherein the members are made of a material comprising at least one metal and/or at least one alloy such as iron, steel, brass, gold, silver, zinc, aluminium, magnesium, titanium, copper, nickel, lead and/or platinum.

8. A system according to any of claims 1-7, wherein at least one of the tube is made of a material that shrinks when exposed to heat.

9. A system according to claim 8, wherein the material that shrinks, shrinks when exposed to temperatures above 80 degrees Celsius, such as above 100 degrees Celsius, such as above 110 degrees Celsius, such as above 120 degrees Celsius, such as above 130 degrees Celsius, such as above 140 degrees Celsius, such as above 150 degrees Celsius, such as above 175 degrees Celsius, such as above 200 degrees Celsius, such as above 225 degrees Celsius, such as above 250 degrees Celsius, such as above 275 degrees Celsius, such as above 300 degrees Celsius, such as above 325 degrees Celsius, such as above 350 5 degrees Celsius.

10. A system according to claim 9, wherein the flow diameter of the at least one tube made from the material that shrinks when exposed to heat, shrinks to 90 percent of the of the starting flow diameter of that tube, such as 80 percent, such as 70 percent, such as 60

10 percent, such as 50 percent, such as 40 percent, such as 30 percent, such as 20 percent, such as 10 percent.

11. A system according to clam 10, wherein the hydraulic flow diameter of a flow channel defined by two members of the system, at least one of the members being made of a

15 material that shrinks when exposed to heat, shrinks to between 0% and 100% of the hydraulic flow diameter before the system was exposed to heat, such as 90%, such as 80%, such as 70%, such as 60%, such as 50%, such as 40%, such as 30%, such as 20%, such as 10 %, such as 0%.

20 12. A system according to claim 1-11, wherein the at least one element is a member of the following group of elements; circular cylindrical shell, half cylinder shell, circular cylinder, semi-cylinder, elliptical cylinder, cylinder with a polygonal cross section, rectangular parallelepiped, spherical shell, hemispherical shell, sphere, hemisphere, conical shell, half conical shell, cone, half cone, semi-ellipsoid, elliptic paraboloid, tetrahedron, torus, three-

25 dimensional-polygon and a rod having any shape of its cross-sectional-area.

13. A system according to claim 1-12, wherein the members of the system are flexible in the longitudinal direction.

30 14. A system according to claim 1-13, wherein the members of the system are stiff in the longitudinal direction.

15. A system according to claim 13 or 14, wherein the at least one element are stiff in the radial direction.

35

16. A system according to claim 15, wherein any member of the system is made of a material having a thermal conductivity greater than 0,1, such as 0,2, such as 0,3, such as 0,5, such as 0,7, such as 1, such as 3, such as 5, such as 10, such as 13, such as 17, such as 20, such as 25, such as 30, such as 40, such as 50, such as 70, such as 100, such as 125, such as 150, such as 175, such as 200, such as 250, such as 300, such as 350, such as 400, such as 450.

17. A system according to claim 16, wherein the at least one element is segmented. 5

18. A system according to any of claims 1-17, wherein the at least one of the at least one tube is a tube for carrying a fluid.

19. A system according to claim 18, wherein the tube is adapted for carrying an acid or a 10 base.

20. A system according to claim 19, wherein the tube is adapted for carrying inflammable fluids.

15 21. A system according to claim 20, wherein the tube is irradiated.

22. A system according to claim 21, wherein the tube is made of polyolefin.

23. A system according to claim 21, wherein the tube is made of poly-tetra-fluoro- 20 ethylene

24. A system according to claim 21, wherein the tube is made of poly-vinylidene-fluoπde.

25. A system according to claim 21, wherein the tube is made of fluoro-ethylene- 25 propylene.

26. A system according to claim 21, wherein the tube is made of per-fluor-alkoxy.

27. A system according to claim 21, wherein the tube is made of ethylene-tetra-fluoro- 30 ethylene-copolymer.

28. A system according to claim 21, wherein the tube is made of ethylene-chloro-tπ- fluoro-ethylene.

35 29. A system according to claim 21, wherein the tube is made of polyvinyl-fluoπde.