CA2093767A1 - Double walled heat exchanger - Google Patents
Double walled heat exchangerInfo
- Publication number
- CA2093767A1 CA2093767A1 CA 2093767 CA2093767A CA2093767A1 CA 2093767 A1 CA2093767 A1 CA 2093767A1 CA 2093767 CA2093767 CA 2093767 CA 2093767 A CA2093767 A CA 2093767A CA 2093767 A1 CA2093767 A1 CA 2093767A1
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- Prior art keywords
- pipe
- heat
- fluid
- heat exchanger
- double walled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A heat exchanger has double walls to avoid the risk of contamination between a heat source fluid and a heat sink fluid. The heat exchanger comprises a conductive pipe for passage of a heat source fluid, the conductive pipe having a turbulator therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductive pipe.
A heat exchanger has double walls to avoid the risk of contamination between a heat source fluid and a heat sink fluid. The heat exchanger comprises a conductive pipe for passage of a heat source fluid, the conductive pipe having a turbulator therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductive pipe.
Description
~937~
DOU~L~ WALL~D H~AT EXC~N~ER
The pressnt invention relates to a heat exchanger for a heat source fluid and a heat sink fluid and wherein double walls are provided to avoid the risk of contamination between the two fluids.
Heat exchangers wherein a heat source fluid provides heat to a heat sink fluid are well known. However, for the majority of these heat exchangers, there is only a single wall thickness between the heat source fluid and the heat sink fluid. Thus, if a leak occurs in this wall, then one fluid contaminates the other and in certain instances this is not acceptable.
It is an aim of the present invention to provide a heat exchanger ~or a heat source fluid and a heat sink fluid wherein the heat source fluid is contained within its own conductive container and is surrounded by conductive coils containing the heat sink fluid, tXe conductive container and the conductive coils being in heat transfer relationship. Thus, if either the contain~r for the heat source fluid or the coils for the heat sink ~luid develop a leak, then that leak does not contaminate the other fluid.
The present invention provides a double walled heat exchanger comprising a conductive pipe for passage of a heat source fluid, the conductive pipe having turbulator means therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductivs pipe.
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In drawings which illustrate embodiments of the present invention, :
.
~3~67 Figure 1 is an isometric view showing a double walled heat exchanger according to one embodiment of the present invention, Figure lA is an isometric view showing another embodiment of a double walled heat exchanger, Figure lB is a detailed isometric view showing a further embodiment of the double walled heat exchanger shown in Figure lA, Figures 2, 3 and 4 are partial sectional views showing different types of conductive tubes suitable for the double walled heat exchanger of the present invention, Figure 5 is an isometric view showing a heat exchanger according to another embodiment of the present invention wherein multiple conductive pipes each have separate conductive tubes coiled there around which are in turn connected to adjacent inflow and outflow headers, Figure 5A is an isometric view showing a heat exchanger similar to that shown in Figure 5 but having three tubes coiled together around each pipe, Figure 6 is a sectional view showing a further embodiment of a doubla walled heat exchanger contained within a tank, the heat exchanger having a plurality of conductive pipes each pipe having conductive tubes coiled there around, Figure 7 is a sectional view taken at line 7-7 of Figure 6, _ 3 _ ~937 ~7 Figure 8 is an isometric view showing a heak exchanger according to a further embodiment of th~
present invention, Figure 9 is a sectional view taken at line 9-9 of Figure 8, Figure lO is an elevational view of a double walled heat exchanger accordiny to a still further embodiment o~
the present invention, wherein a conductive tube and a conductive pipe are twisted togetherO
The term "fluid" is used throughout the specification and refers to either liquid or gas.
rrypical examples of fluids, but not limiting, are water, steam, hot gas, hot air, flue gas, and other types of heat exchange liquids~
A heat exchanger lO is shown in Figure 1 having a pipe 12 through which a hot fluid, which is a heat source fluid, flows downwards. Inside the pipe 12 is a turbulator which comprises twisted ribbon 14 extending across the diameter of the inside of pipe 12 and having a series of punched out flaps 16 extending first on one side and then the other side to cause turbulation in the fluid flowing through the pipe 12, this turbulation results in a better transfer of heat between the heat source fluid and the heat sink fluid.
Whereas the twisted ribbon 14 is shown extending across the inside diameter of the pipe 12, in another e~bodiment the ribbon may only extend for khe radius of the pip~. Other configurations of turbulators such as curved fins and the like may be provided, the purpose being to cause turbulation in the fluid which results in an increase in the transfer of heat from the heat source liquid to the surfaces of the pipe 12, and then to the heat sink fluid.
In Figure lA, another embodiment of a turbulator shows a coiled solid rod 17 which, in Figure lA is shown as round and in Figure lB i9 shown as rectangular in cross section, is in contact with the inside of the pipe 12. The coiled rod 17 is placed in position by being wound into a helical spring configuration, inserted into the pipe 12, and then released so that the rod 17 is forced against the inside surface of the pipe 12 for the length of the rod 17 or pipe 12. The rod 17 increases the heat transfer surface area in the pipe 12 contacted by fluid therein to increase heat transfer. A twisted ribbon 14 extends across the inside of the pipe 12, inside the coiled rod 17. The ribbon 14 causes turbulation in the pipe. Figure lA does not show flaps 16 therein, but for certain fluids, the flaps, as shown in Figure 1, are included in the ribbon configuration of Figures lA and lB.
A tube 18 is shown coiled about the pipe 12. The tube 18 is preferably in contact with the pipe 12 foxming a heat transfer relationship between the tube 18 and the pipe 12. Whereas one tube 18 is shown, it will be apparent that two or more tubes 18 may be coiled together about the pipe 12.
The materials of construction require conductive materials. The pipe 12 may be steel, copper, or indeed in some instances, plastic. The tube 18 may be plastic or copper. Other suitable materials may be used which have a high heat transferability and are compatible with the fluids.
Figures 2, 3 and 4 show other embodiments wherein the tube 18 has a different configuration~ In Figure 2 .
_ 5 - 2~ g 37~7 the tube 18 is substantially rectangular~ in Figure 3 the tube 18 is substantially oval and in Figure 4 the tube 18 is substantially D-shaped so that the surface of the tube 18 contacting the pipe 12 is maximized for heat transferO
The purpose is to obtain maximum heat transfer between the tube 18 and the pipe 12, however, t:he tube 18 is not necessarily attached to the pipe 12. In certain circumstances the tube 18 may be soldered or braised to the pipe 12 for the full length of the tube 18~ at points along the tube 18 or at the top and bottom o the tube 18. Maximum heat transfer is obtained between the tube 18 and the pipe 12, but if a leak or split occurs in either the tube 18 or the pipe 12, it does not extend between the two. The fluids in the pipe 12 and the tube 18 do not contaminate each other, and if leaks occur, fluid seeps into the space around the pipes 12 and tubes 18.
If a leak occurs at the bottom of a heat exchanger it can be observed, or in one embodiment an electrical detector is placed to monitor leaks and provide an appropriate warning.
In Figure 5 a large inlet header 22 is shown at the bottom and has T-connections to three pipes 12. The pipes 12 extend to join an outlet header 20 at the top and as can be seen, the heat source fluid flows in at the inlet header 22 at the bottom and out through the outlet header 20 at the top passing through pipes 12. Around each pipe 12 is a tube 18 coiled about the pipe 12 and connected to an inflow header 26 at the top which in turn is connected to an outflow header 24 at the bottom. Each of the tubes 18 is connected to the inflow header 26 at the top and the outflow header 24 at the bottom. Eeat sink fluid flows through the tubes 18 and is heated by the heat source fluid flowing through the pipes 12. The - 6 - 2~3~6~
pipes 12 as illustrated are substantially vertical and the heat sink fluid flows down through the tubes 18.
In one e~oodiment, insulation 28 surrounds the tube 18 coiled about the pipe 12. The insulation 28 contains the heat preventing heat loss in khe heat exchanger.
In Figure 5A, three separate tubes 18A, 18B and 18C
are shown connected to the inflow header 26 and the outflow header 24 and are wrapped side by side around each pipe 12. The dimensions of the tubes 18At 18B and 18C are determined by the flow requirements and heat.in~
requirements.
The Figures show the pipes 12 positioned substantially vertical, however/ in other embodiments the pipes may be in a horizontal plane or at any angle to suit space or other requirements.
In another embodiment, a tank 30 is shown in Figures 6 and 7 having a plurality of vertical pipes 12 which extend from a bottom plate 32 to a top plate 33 within the tank 30 and are contained within a tank wall 31. A
heat source fluid, which is in one embodiment hot water from a hot water boiler (not shown), enters a lower inlet 34 into a space 36 in the tank 30 beneath the lower plate 32, the heat source fluid passes upwards through the pipes 12 into a space 38 in the tank 30 above the top plate 33 and then passes to the upper outlet 40 at the top of the tank 30.
An inflow header 26 for the heat sink fluid, which aga.in is preferably water, connects to a series of inflow ducts 44 as shown in Figure 7 passing through the tank wall 31 and has connections to a plurality of coiled tubes 18 each surrounding a pipe 12. The heat sink fluid in the tubes 18 flows downwards and heat is transferred _ 7 _ ~ ~937~7 to the tubes 18 from the pipes 12. The tubes 18 at the base are connected to outflow ducts 46 which in turn pass out through the tank wall 31 and are connected to an outflow header 24. In this example, the hea sink fluid enters at the top of the tubes 18 and moves downwards whereas the heat source fluid enters at the bottom of the pipes 12 and moves upwards.
In other embodiments, the heat source fluid in the pipes 12 flows in either direction, if the pipes are not vertical then upwards or downwards is not applicable.
The heat sink fluid in the tubes 18 flows in the same direction as the heat source fluid flow or counter to that flow depending upon the heating requirements and other considerations.
~he pipes 12 shown in both Figure 5 and Figure 6 have a turbulator arrangement in the forn. of a ribbon 14 inside to ensure maximum heat transfer occurs between the heat source fluid and the walls of the pipes 12. The tank 30 and pipes 12 are preferably made of mild steel welded together to ensure that no leak occurs into the space around the pipes in the tank 30 from the connection between the pipes 12 and the bottom plate 32 and top plate 33. In the case of a domestic water heater, the tubes 18 may be copper, stainless steel, plastic, or other suitable material, similarly the inflow header 26 and inflow ducts 44 and the outflow header 24 and outflow ducts 46 may also be copper, stainless steel, plastic, or other suitable material. The heat exchanger 10 utilizes a hot water source (not shown) for the heat source fluid, and heats water or other fluid in the tubes 18. No contact can exist between the two fluids as even if a leak occurs in one of the pipes 12 or tubes 18, the fluid escapes into the space around the pipes 12 in the tank 30, and can be allowed to drain to the outside of the tank 30.
- 8 ~ 2~937~7 The space in the tank 30 may be filled with heat insulation material, or contain air, or evacuated to form a vacuum, in which case the heat txansfer relies on the contact between the tubes 18 and the pipes 12. In another embodiment~ a heat transfer medium such as oil may be provided in the space around the pipes 12 in the tank 30 so that there is increased heat: transfer from the pipes 12 not only to the tubes 18 but to the heat transfer medium which in turn assists in heating the tubes 18. The heat transfer medium as stated may be oil, brine or other suitable liquid, however, it is preferable that the heat transfer medium liquid is kept at a lower pressure than the heat source fluid in the pipes 12 or the heat sink fluid in the tubes 18. Thus, if a leak does occur from the heat source fluid supply or the he~t sink 1uid supply, then because the pressure is higher than the heat transfer medium, tken no heat transfer medium enters the pipes 12 or tubes 18.
While not shown, the tank 30 may have heat insulation around it to conserve heat as may the inlet 34 and outlet 40 pipes as well as the inflow header 26 and outflow header 24. In another embodiment, insulation may be placed inside the tank around the coiled tubes 18 as shown in Figure 5 to ensure that the heat transfer between the pipes 12 and the tubes 18 is maximized and heat is not wasted.
Another embodiment of a heat exchanger is shown in Figures 8 and 9 wherein a two stage arrangement is disclosed. The heat source fluid enters inlet header 22 flows through the first set of pipes 12 into an intermediate hea~er 50, which has a U-bend at one end.
The heat source fluid passes around the U-bend and enters the second set of pipes 12 passing into the outlet header 20. The heat sink fluid enters from the inflow header 26 placed along side the outlet header 20, and passes _ 9 ~3~7 through a first set of tubes 18 wrapped around the second set of pipes 12 feeding into a first stage header 52 which is shown having a U-bend at one end turning into a second stage header 54. The heat sink fluid then flows through the second set o tubes 18 wrapped around the first set of pipes 12 and into the outflow header 24 positioned beside the inlet header 22.
The two stage heat exchanger provides a higher temperature and a lower flow rate. In another embodiment, the first stage header 52 and second stage header 54 are not co~mected, providing two single stage heaters. Such an arrangement provides lower temperature but increased flow rate over the two stage heat exchanger.
Figure 10 shows a further embodiment of a heat exchanger wherein a pipe 12 is twis~ed with a tube 18.
The pipe 12 contains heat source fluid and the ~ube 18 the heat sink fluid. The pipes 12 and tube 18 are in contact with each other in heat exchange relationship.
~or purposes of definition the pipe 12 containing heat source fluid is defined as a pipe, but may be a tube of the same type of material as the tube 18 for the heat sink fluids. The pipe 12 and tube 18 may be made of the same material and may have similar diameters or, alternatively may have different diameters. The twisted pipe 12 forms a turbulator and therefore it is not essential to have a twistecl ribbon therein.
Whereas the pipes 12 have been defined as containing heat source fluid, and the tubes 18 as containing heat sink fluid, the heat exchanger is reversible so that heat sink fluid is passed through the pipes 12 and heat source fluid through the tubes 18. The transfer of hea-t is then reversed. This reversal may occur as a permanent 2~37~7 arrangement or may change based on the particular requirement of the heat exchanger.
Various changes may be made to the embodiments shown herein without departing from the scope o:E the present invention which is limited only by the following claims.
DOU~L~ WALL~D H~AT EXC~N~ER
The pressnt invention relates to a heat exchanger for a heat source fluid and a heat sink fluid and wherein double walls are provided to avoid the risk of contamination between the two fluids.
Heat exchangers wherein a heat source fluid provides heat to a heat sink fluid are well known. However, for the majority of these heat exchangers, there is only a single wall thickness between the heat source fluid and the heat sink fluid. Thus, if a leak occurs in this wall, then one fluid contaminates the other and in certain instances this is not acceptable.
It is an aim of the present invention to provide a heat exchanger ~or a heat source fluid and a heat sink fluid wherein the heat source fluid is contained within its own conductive container and is surrounded by conductive coils containing the heat sink fluid, tXe conductive container and the conductive coils being in heat transfer relationship. Thus, if either the contain~r for the heat source fluid or the coils for the heat sink ~luid develop a leak, then that leak does not contaminate the other fluid.
The present invention provides a double walled heat exchanger comprising a conductive pipe for passage of a heat source fluid, the conductive pipe having turbulator means therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductivs pipe.
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In drawings which illustrate embodiments of the present invention, :
.
~3~67 Figure 1 is an isometric view showing a double walled heat exchanger according to one embodiment of the present invention, Figure lA is an isometric view showing another embodiment of a double walled heat exchanger, Figure lB is a detailed isometric view showing a further embodiment of the double walled heat exchanger shown in Figure lA, Figures 2, 3 and 4 are partial sectional views showing different types of conductive tubes suitable for the double walled heat exchanger of the present invention, Figure 5 is an isometric view showing a heat exchanger according to another embodiment of the present invention wherein multiple conductive pipes each have separate conductive tubes coiled there around which are in turn connected to adjacent inflow and outflow headers, Figure 5A is an isometric view showing a heat exchanger similar to that shown in Figure 5 but having three tubes coiled together around each pipe, Figure 6 is a sectional view showing a further embodiment of a doubla walled heat exchanger contained within a tank, the heat exchanger having a plurality of conductive pipes each pipe having conductive tubes coiled there around, Figure 7 is a sectional view taken at line 7-7 of Figure 6, _ 3 _ ~937 ~7 Figure 8 is an isometric view showing a heak exchanger according to a further embodiment of th~
present invention, Figure 9 is a sectional view taken at line 9-9 of Figure 8, Figure lO is an elevational view of a double walled heat exchanger accordiny to a still further embodiment o~
the present invention, wherein a conductive tube and a conductive pipe are twisted togetherO
The term "fluid" is used throughout the specification and refers to either liquid or gas.
rrypical examples of fluids, but not limiting, are water, steam, hot gas, hot air, flue gas, and other types of heat exchange liquids~
A heat exchanger lO is shown in Figure 1 having a pipe 12 through which a hot fluid, which is a heat source fluid, flows downwards. Inside the pipe 12 is a turbulator which comprises twisted ribbon 14 extending across the diameter of the inside of pipe 12 and having a series of punched out flaps 16 extending first on one side and then the other side to cause turbulation in the fluid flowing through the pipe 12, this turbulation results in a better transfer of heat between the heat source fluid and the heat sink fluid.
Whereas the twisted ribbon 14 is shown extending across the inside diameter of the pipe 12, in another e~bodiment the ribbon may only extend for khe radius of the pip~. Other configurations of turbulators such as curved fins and the like may be provided, the purpose being to cause turbulation in the fluid which results in an increase in the transfer of heat from the heat source liquid to the surfaces of the pipe 12, and then to the heat sink fluid.
In Figure lA, another embodiment of a turbulator shows a coiled solid rod 17 which, in Figure lA is shown as round and in Figure lB i9 shown as rectangular in cross section, is in contact with the inside of the pipe 12. The coiled rod 17 is placed in position by being wound into a helical spring configuration, inserted into the pipe 12, and then released so that the rod 17 is forced against the inside surface of the pipe 12 for the length of the rod 17 or pipe 12. The rod 17 increases the heat transfer surface area in the pipe 12 contacted by fluid therein to increase heat transfer. A twisted ribbon 14 extends across the inside of the pipe 12, inside the coiled rod 17. The ribbon 14 causes turbulation in the pipe. Figure lA does not show flaps 16 therein, but for certain fluids, the flaps, as shown in Figure 1, are included in the ribbon configuration of Figures lA and lB.
A tube 18 is shown coiled about the pipe 12. The tube 18 is preferably in contact with the pipe 12 foxming a heat transfer relationship between the tube 18 and the pipe 12. Whereas one tube 18 is shown, it will be apparent that two or more tubes 18 may be coiled together about the pipe 12.
The materials of construction require conductive materials. The pipe 12 may be steel, copper, or indeed in some instances, plastic. The tube 18 may be plastic or copper. Other suitable materials may be used which have a high heat transferability and are compatible with the fluids.
Figures 2, 3 and 4 show other embodiments wherein the tube 18 has a different configuration~ In Figure 2 .
_ 5 - 2~ g 37~7 the tube 18 is substantially rectangular~ in Figure 3 the tube 18 is substantially oval and in Figure 4 the tube 18 is substantially D-shaped so that the surface of the tube 18 contacting the pipe 12 is maximized for heat transferO
The purpose is to obtain maximum heat transfer between the tube 18 and the pipe 12, however, t:he tube 18 is not necessarily attached to the pipe 12. In certain circumstances the tube 18 may be soldered or braised to the pipe 12 for the full length of the tube 18~ at points along the tube 18 or at the top and bottom o the tube 18. Maximum heat transfer is obtained between the tube 18 and the pipe 12, but if a leak or split occurs in either the tube 18 or the pipe 12, it does not extend between the two. The fluids in the pipe 12 and the tube 18 do not contaminate each other, and if leaks occur, fluid seeps into the space around the pipes 12 and tubes 18.
If a leak occurs at the bottom of a heat exchanger it can be observed, or in one embodiment an electrical detector is placed to monitor leaks and provide an appropriate warning.
In Figure 5 a large inlet header 22 is shown at the bottom and has T-connections to three pipes 12. The pipes 12 extend to join an outlet header 20 at the top and as can be seen, the heat source fluid flows in at the inlet header 22 at the bottom and out through the outlet header 20 at the top passing through pipes 12. Around each pipe 12 is a tube 18 coiled about the pipe 12 and connected to an inflow header 26 at the top which in turn is connected to an outflow header 24 at the bottom. Each of the tubes 18 is connected to the inflow header 26 at the top and the outflow header 24 at the bottom. Eeat sink fluid flows through the tubes 18 and is heated by the heat source fluid flowing through the pipes 12. The - 6 - 2~3~6~
pipes 12 as illustrated are substantially vertical and the heat sink fluid flows down through the tubes 18.
In one e~oodiment, insulation 28 surrounds the tube 18 coiled about the pipe 12. The insulation 28 contains the heat preventing heat loss in khe heat exchanger.
In Figure 5A, three separate tubes 18A, 18B and 18C
are shown connected to the inflow header 26 and the outflow header 24 and are wrapped side by side around each pipe 12. The dimensions of the tubes 18At 18B and 18C are determined by the flow requirements and heat.in~
requirements.
The Figures show the pipes 12 positioned substantially vertical, however/ in other embodiments the pipes may be in a horizontal plane or at any angle to suit space or other requirements.
In another embodiment, a tank 30 is shown in Figures 6 and 7 having a plurality of vertical pipes 12 which extend from a bottom plate 32 to a top plate 33 within the tank 30 and are contained within a tank wall 31. A
heat source fluid, which is in one embodiment hot water from a hot water boiler (not shown), enters a lower inlet 34 into a space 36 in the tank 30 beneath the lower plate 32, the heat source fluid passes upwards through the pipes 12 into a space 38 in the tank 30 above the top plate 33 and then passes to the upper outlet 40 at the top of the tank 30.
An inflow header 26 for the heat sink fluid, which aga.in is preferably water, connects to a series of inflow ducts 44 as shown in Figure 7 passing through the tank wall 31 and has connections to a plurality of coiled tubes 18 each surrounding a pipe 12. The heat sink fluid in the tubes 18 flows downwards and heat is transferred _ 7 _ ~ ~937~7 to the tubes 18 from the pipes 12. The tubes 18 at the base are connected to outflow ducts 46 which in turn pass out through the tank wall 31 and are connected to an outflow header 24. In this example, the hea sink fluid enters at the top of the tubes 18 and moves downwards whereas the heat source fluid enters at the bottom of the pipes 12 and moves upwards.
In other embodiments, the heat source fluid in the pipes 12 flows in either direction, if the pipes are not vertical then upwards or downwards is not applicable.
The heat sink fluid in the tubes 18 flows in the same direction as the heat source fluid flow or counter to that flow depending upon the heating requirements and other considerations.
~he pipes 12 shown in both Figure 5 and Figure 6 have a turbulator arrangement in the forn. of a ribbon 14 inside to ensure maximum heat transfer occurs between the heat source fluid and the walls of the pipes 12. The tank 30 and pipes 12 are preferably made of mild steel welded together to ensure that no leak occurs into the space around the pipes in the tank 30 from the connection between the pipes 12 and the bottom plate 32 and top plate 33. In the case of a domestic water heater, the tubes 18 may be copper, stainless steel, plastic, or other suitable material, similarly the inflow header 26 and inflow ducts 44 and the outflow header 24 and outflow ducts 46 may also be copper, stainless steel, plastic, or other suitable material. The heat exchanger 10 utilizes a hot water source (not shown) for the heat source fluid, and heats water or other fluid in the tubes 18. No contact can exist between the two fluids as even if a leak occurs in one of the pipes 12 or tubes 18, the fluid escapes into the space around the pipes 12 in the tank 30, and can be allowed to drain to the outside of the tank 30.
- 8 ~ 2~937~7 The space in the tank 30 may be filled with heat insulation material, or contain air, or evacuated to form a vacuum, in which case the heat txansfer relies on the contact between the tubes 18 and the pipes 12. In another embodiment~ a heat transfer medium such as oil may be provided in the space around the pipes 12 in the tank 30 so that there is increased heat: transfer from the pipes 12 not only to the tubes 18 but to the heat transfer medium which in turn assists in heating the tubes 18. The heat transfer medium as stated may be oil, brine or other suitable liquid, however, it is preferable that the heat transfer medium liquid is kept at a lower pressure than the heat source fluid in the pipes 12 or the heat sink fluid in the tubes 18. Thus, if a leak does occur from the heat source fluid supply or the he~t sink 1uid supply, then because the pressure is higher than the heat transfer medium, tken no heat transfer medium enters the pipes 12 or tubes 18.
While not shown, the tank 30 may have heat insulation around it to conserve heat as may the inlet 34 and outlet 40 pipes as well as the inflow header 26 and outflow header 24. In another embodiment, insulation may be placed inside the tank around the coiled tubes 18 as shown in Figure 5 to ensure that the heat transfer between the pipes 12 and the tubes 18 is maximized and heat is not wasted.
Another embodiment of a heat exchanger is shown in Figures 8 and 9 wherein a two stage arrangement is disclosed. The heat source fluid enters inlet header 22 flows through the first set of pipes 12 into an intermediate hea~er 50, which has a U-bend at one end.
The heat source fluid passes around the U-bend and enters the second set of pipes 12 passing into the outlet header 20. The heat sink fluid enters from the inflow header 26 placed along side the outlet header 20, and passes _ 9 ~3~7 through a first set of tubes 18 wrapped around the second set of pipes 12 feeding into a first stage header 52 which is shown having a U-bend at one end turning into a second stage header 54. The heat sink fluid then flows through the second set o tubes 18 wrapped around the first set of pipes 12 and into the outflow header 24 positioned beside the inlet header 22.
The two stage heat exchanger provides a higher temperature and a lower flow rate. In another embodiment, the first stage header 52 and second stage header 54 are not co~mected, providing two single stage heaters. Such an arrangement provides lower temperature but increased flow rate over the two stage heat exchanger.
Figure 10 shows a further embodiment of a heat exchanger wherein a pipe 12 is twis~ed with a tube 18.
The pipe 12 contains heat source fluid and the ~ube 18 the heat sink fluid. The pipes 12 and tube 18 are in contact with each other in heat exchange relationship.
~or purposes of definition the pipe 12 containing heat source fluid is defined as a pipe, but may be a tube of the same type of material as the tube 18 for the heat sink fluids. The pipe 12 and tube 18 may be made of the same material and may have similar diameters or, alternatively may have different diameters. The twisted pipe 12 forms a turbulator and therefore it is not essential to have a twistecl ribbon therein.
Whereas the pipes 12 have been defined as containing heat source fluid, and the tubes 18 as containing heat sink fluid, the heat exchanger is reversible so that heat sink fluid is passed through the pipes 12 and heat source fluid through the tubes 18. The transfer of hea-t is then reversed. This reversal may occur as a permanent 2~37~7 arrangement or may change based on the particular requirement of the heat exchanger.
Various changes may be made to the embodiments shown herein without departing from the scope o:E the present invention which is limited only by the following claims.
Claims (24)
1. A double walled heat exchanger comprising:
a conductive pipe for passage of a heat source fluid, the conductive pipe having turbulator means therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductive pipe.
a conductive pipe for passage of a heat source fluid, the conductive pipe having turbulator means therein to maximize heat transfer between the heat source fluid and the conductive pipe, and at least one conductive tube coiled around the conductive pipe for passage of a heat sink fluid therethrough, the tube in heat transfer relationship with the conductive pipe.
2. The double walled heat exchanger according to claim 1 wherein the tube is in contact with the pipe.
3. The double walled heat exchanger according to claim 1 wherein the tube cross-section is selected from the group consisting of round, rectangular, oval and D-shaped.
4. The double walled heat exchanger according to claim 1 including a plurality of pipes connected to an inlet header and an outlet header, each of the plurality of pipes having at least one conductive tube coiled there around, each tube having an inflow end connected to an inflow header and an outflow end connected to an outflow header.
5. The double walled heat exchanger according to claim 4 wherein the inlet header for the pipes is positioned adjacent the outflow header for the tubes.
6. The double walled heat exchanger according to claim 4 wherein the pipes are vertical and the outlet header for the pipes is on top.
7. The double walled heat exchanger according to claim 4 wherein the plurality of pipes are arranged within a tank and extend from a bottom plate to a top plate in the tank, a space is provided in the tank below the bottom plate to form the inlet header and a space is provided in the tank above the top plate to form the outlet header, each pipe in the tank having at least one conductive tube wrapped there around, the tubes connected to inflow header means and outflow header means.
8. The double walled heat exchanger according to claim 7 wherein heat source fluid flows upwards in the pipes and heat sink fluid flows downwards in the tubes.
9. The double walled heat exchanger according to claim 7 wherein heat transfer medium is provided in the tank between the top plate and the bottom plate to assist in heat transfer between the pipes and the tubes.
10. The double walled heat exchanger according to claim 1 wherein the turbulator means comprises a twisted ribbon within the pipe.
11. The double walled heat exchanger according to claim 1 wherein the turbulator means comprises a coiled solid rod in a helical spring configuration, pressing against an inside surface of the pipe, and including a twisted ribbon within the coiled solid rod.
12. The double walled heat exchanger according to claim 10 wherein the twisted ribbon has a plurality of slots cut therein with flaps extending outwards from the ribbon to assist in providing a turbulent flow of heat source fluid through the pipe.
13. The double walled heat exchanger according to claim 1 wherein the conductive pipe and the conductive tube are twisted together.
14. The double walled heat exchanger according to claim 4 wherein the heat source fluid flows counter to the heat sink fluid.
15. The double walled heat exchanger according to claim 4 wherein the heat source fluid flows in substantially the same direction as the heat sink fluid.
16. The double walled heat exchanger according to claim 4 wherein two stages of pipes occur between the inlet header and the outlet header, and two stages of tubes occur between an inflow header and an outflow header.
17. The double walled heat exchanger according to claim 1 wherein the conductive pipe is adapted to have a heat sink fluid pass therethrough and the conductive tube has a heat source fluid pass therethrough.
18. A process of transferring heat from a heat source fluid to a heat sink fluid comprising the steps of:
providing a turbulent flow of heat source fluid through a pipe, providing a flow of heat sink fluid through a tube coiled about the pipe and in heat transfer relationship with the heat source fluid in the pipe to thereby heat the heat sink fluid.
providing a turbulent flow of heat source fluid through a pipe, providing a flow of heat sink fluid through a tube coiled about the pipe and in heat transfer relationship with the heat source fluid in the pipe to thereby heat the heat sink fluid.
19. The process of transferring heat from a heat source fluid to a heat sink fluid as claimed in claim 18, including providing the flow of heat source fluid upwards through the pipe, and providing the flow of heat sink fluid downwards through the coils.
20, The process of transferring heat from a heat source fluid to a heat sink fluid according to claim 18 wherein the heat sink fluid flows through the pipe and the heat source fluid flows through the tube.
21. A turbulator for causing turbulation in a fluid to increase heat transfer, comprising:
a pipe for the passage of fluid therethrough, a coiled rod in a helical spring configured in the pipe pressing on an inside surface of the pipe, and a twisted ribbon within the coiled rod in the pipe extending to contact the inside of the coiled rod.
a pipe for the passage of fluid therethrough, a coiled rod in a helical spring configured in the pipe pressing on an inside surface of the pipe, and a twisted ribbon within the coiled rod in the pipe extending to contact the inside of the coiled rod.
22. The turbulator according to claim 21 wherein the coiled rod comprises a solid rod with a round cross section.
23. The turbulator according to claim 21 wherein the coiled rod comprises a solid rod with a rectangular cross section.
24. The turbulator according to claim 21 wherein the twisted ribbon has a plurality of slots cut therein with flaps extending outwards from the ribbon to assist in providing a turbulent flow of fluid through the pipe.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86724792A | 1992-04-10 | 1992-04-10 | |
| US07/867,247 | 1992-04-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2093767A1 true CA2093767A1 (en) | 1993-10-11 |
Family
ID=25349415
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2093767 Abandoned CA2093767A1 (en) | 1992-04-10 | 1993-04-08 | Double walled heat exchanger |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN1083917A (en) |
| CA (1) | CA2093767A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102022933A (en) * | 2010-12-16 | 2011-04-20 | 中国扬子集团滁州扬子空调器有限公司 | Wound pipe heat exchanger |
-
1993
- 1993-04-08 CA CA 2093767 patent/CA2093767A1/en not_active Abandoned
- 1993-04-10 CN CN 93105739 patent/CN1083917A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN1083917A (en) | 1994-03-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |