CA2170197A1 - Vacuum chambered heat exchanger - Google Patents
Vacuum chambered heat exchangerInfo
- Publication number
- CA2170197A1 CA2170197A1 CA002170197A CA2170197A CA2170197A1 CA 2170197 A1 CA2170197 A1 CA 2170197A1 CA 002170197 A CA002170197 A CA 002170197A CA 2170197 A CA2170197 A CA 2170197A CA 2170197 A1 CA2170197 A1 CA 2170197A1
- Authority
- CA
- Canada
- Prior art keywords
- tube
- medium
- heat exchanger
- heat
- wall
- 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.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F1/00—Tubular elements; Assemblies of tubular elements
- F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
- F28F1/42—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Geometry (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
A heat exchanger comprising first and second tubes respectively receiving a cold and a hot fluid is disclosed herein. The heat exchanger is enclosed in a vacuum chamber to improve its efficiency.
Description
2 1 7U I ~7 TITLE OF THE lNV~NLlON
VACWM CHAMBERED HEAT EXCHANGER
FIELD OF THE lNV~NllON
The present invention relates to heat exchangers. More particularly, the present invention relates to heat exchangers adapted to heat or to cool flowable or pumpable mediums.
R~C~ROUND OF THE lNV~N-llON
The prior art is replete with heat exchangers consisting of a first tube inserted in a second tube and in which a hot fluid is introduced in the first tube and a cold fluid is introduced in the second tube. The purpose of these heat exchangers is to increase the temperature of the cold fluid of the second tube or to decrease the temperature of the hot fluid of the first tube. However, in both cases, the physical effect is a transfer of heat from the hot .
fluid to the cold fluid to cool the hot fluid and to heat the cool fluid.
For example, U.S. Patent N 4,554,969 issued on November 26, 1985 to Carnavos describes a coaxial finned tube heat exchanger having an inner tube and an outer tube.
U.S. Patent N4,893,670 issued on January 16, 1990 to Joshi et al. describes a heat exchanger combining an oil cooler and a radiator hose. This heat exchanger comprises two generally concentric hoses provided with internal deflectable vanes. In this case, the hot fluid (the oil) is supplied to the external hose while the cold fluid (the engine coolant) is supplied to the internal hose.
A drawback of the above discussed heat exchangers is their relatively poor efficiency when the amount of heat to be recuperated from a hot fluid and transferred to a cold fluid is substantial.
Indeed, the fluid introduced in the outer tube of conventional heat exchangers has intimate contact with the air surrounding this outer tube. Since this air is usually at a lower temperature with respect to the temperature of the fluid introduced in the outer tube, part of the heat of this fluid is transferred to the air, therefore reducing the overall efficiency of the 21 701 ~7 heat exchanger. The efficiency of conventional heat exchangers therefore decreases with the increase of the temperature of the fluid of the outer tube.
OBJECTS OF THE lNV~;N-l lON
An object of the present invention is therefore to provide an improved efficiency heat exchanger.
Another object of the invention is to provide a heat exchanger at least partially enclosed in a vacuum chamber to thereby insulate the heat exchanger from the external environment.
SU~ARY OF THE lNv~ LloN
More specifically, in accordance with the present invention, there is provided a heat exchanger for exchanging heat between a first and second medium having respective flow rates; the heat exchanger comprises:
a) a first tube for receiving the first medium, the first tube having first and second ends 2] 701 ~7 respectively providing first medium inlet and first medium outlet, the first tube also having an outer wall;
b) a second tube for receiving the second medium, the second tube having first and second ends respectively providing second medium inlet and second medium outlet, the second tube also having an inner wall; the second tube being in close contact with the first tube to enable heat exchange between the first 0 medium and the second medium; and c) a vacuum chamber enclosing at least a portion of the first and second tubes;
whereby, the exchange of heat between the first and second mediums is improved by a vacuum provided in the vacuum chamber, thereby increasing the efficiency of the heat exchanger.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.
21 701 ~7 BRIEF DESCRIPTION OF THE DRAWINGS
In the appended drawings:
Figure 1 illustrates a side elevational view, partially in section, of a heat exchanger according to a first embodiment of the present invention;
Figure 2 is a sectional view taken along line 2-2 of Figure 1;
Figure 3 is a sectional view taken along line 3-3 of Figure 2; and Figure 4 illustrates a side elevational view, partially in section, of a heat exchanger according to a second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It is to be noted that the terms "hot" and "cold" are relative and used herein to generally 2170~q7 describe the temperature of the fluids. More specifically, the term "hot fluid" means than the fluid is at a higher temperature than the "cold fluid", and vice-versa. Furthermore, the term "fluid"
is used herein to describe any gaseous, liquid or semi-liquid flowable and pumpable mediums.
It has been found that by enclosing a heat exchanger in an enclosure held under a partial vacuum (this enclosure will hereinafter be referred to as the vacuum chamber), it is possible to increase the overall efficiency of the heat exchanger.
Two physical properties may be considered to explain the increase in efficiency of a heat exchanger enclosed in a vacuum chamber. First, the vacuum chamber insulates the heat exchanger from the external environment, which ensures that no heat is ~lost" to the ambient air. Second, since the boiling point of the fluids in the heat exchanger is reduced by the reduction of air pressure, it is believed that the transfer of heat is eased.
Turning now to Figures 1-3 of the appended drawings, a heat exchanger 10 according to a first embodiment of the present invention will be described.
2 1 70 1 q7 The heat exchanger 10 includes an enclosure 12 defining a chamber 14, an outer tube 16, an inner tube 18, an air outlet 20 and an air pressure meter 22.
As illustrated in Figure 1, the inner tube 18 is inserted in the outer tube 16 and these tubes describe a multiple "Sn shape. Of course, this multiple "S" shape is intended to reduce the space required for the heat exchanger 10 and to slow the flows of fluid therein to thereby increase the residence time of the fluids in the outer and inner tubes 16 and 18.
The outer tube 16 includes a fluid inlet 24 and a fluid outlet 26 having a cross sectional area larger than the fluid inlet 24 as explained hereinafter.
The inner tube 18 includes a fluid inlet 28 and a fluid outlet 30.
The inner tube 18 has a first angled portion 34 near the outlet 32 and enters the outer 25 tube 16 through an aperture 36 provided near the inlet 24.
Similarly, the inner tube 18 has a second angled portion 38 near the inlet 30 and enters the outer tube 16 through an aperture 40 provided near the outlet 24.
Therefore, a significant portion of the inner tube 18 is enclosed in the outer tube 16.
A source of hot fluid (not shown) may be connected between the inlet 30 and the outlet 32 of the inner tube 18 therefore to supply the heat exchanger 10 with hot fluid (see arrows 42 and 44).
Similarly, a source of cold fluid (not shown) may be connected between the inlet 24 and the outlet 26 of 15 the outer tube 16 therefore to supply the heat exchanger 10 with cold fluid (see arrows 46 and 48) .
Heat will therefore be transferred from the hot fluid to the cold fluid, thereby cooling said 20 hot fluid and heating said cold fluid.
Turning to Figure 2, the inner tube 18 also includes a plurality of wings 50 mounted on its outer wall. These wings define an acute angle with 25 respect to the direction of the flow of the cold fluid (see arrow 52), thereby decreasing the flow rate of the cold fluid. This characteristic has a direct effect on the period of residence of the cold fluid in the heat exchanger 10 since the decrease of the flow rate increases the period of residence of the cold fluid in the outer tube 16, thereby improving the heat transfer between the hot and cold fluids by keeping them in contact a longer period.
As illustrated in Figure 3, the wings 50 are circumferentially disposed around said inner tube 18 while providing gaps 54. Of course, the wings 50 could be replaced by other types of flow decreasing members such as fins, ribs, or the like. It has however been found that wings 50 having an acute angle with respect to the direction of flow of the cold fluid operate in a satisfactory manner.
As will be easily understood to one of ordinary skills in the art, since the flow rate of the cold fluid is decreased by the wings 50, the area of the outlet 26 of the cold fluid must be increased since the flow of cold fluid entering through the inlet 24 and the flow of cold fluid exiting through the outlet 26 is identical and that the flow rate is decreased.
The enclosure 12 is substantially airtight to enable the creation of a partial vacuum in the chamber 14. The air outlet 20 may be connected to a vacuum pump (not shown) to thereby draw the air ~ 21 701 97 present in the enclosure. The meter 22 indicates the air pressure level in the chamber 14. A valve (not shown) may be provided to close the air outlet 20 when a predetermined vacuum level is reached.
The operation of the heat exchanger 10 will be described by the way of the following non limitative example of installation of a heat exchanger in an industrial facility.
A heat exchanger similar to the heat exchanger 10 has been installed in an industrial abattoir requiring a substantial amount of hot water and having a plurality of freezers using conventional refrigeration systems. The purpose of this installation was to use the excess heat generated by the refrigeration systems to efficiently heat the water to a sufficient temperature so as to eliminate the need for conventional electrical heating elements in the water heaters.
As will be evident to one of ordinary skills in the art of refrigerating systems, the compressor used to refrigerate a freezer, or the like, generally use a radiator to cool the gases having absorbed heat in the freezer.
To use a portion of this heat present in the hot gases of the refrigeration system, the inner tube 18 of the heat exchanger 10 has been inserted in parallel with the above mentioned radiator to thereby receive a predetermined and variable portion of the hot gases exiting the compressor. These hot gases enter the inner tube 18 through the hot fluid inlet 30 and exit the inner tube 18 through the hot fluid outlet 32.
As will be obvious to one of ordinary skills in the art, sufficient heat must remain in the hot gases returning to the refrigeration system for adequate operation of the refrigeration system. It is therefore advantageous to supply only a portion of the hot gases to the inner tube 18 of the heat exchanger 10 .
As previously mentioned industrial abattoirs use a substantial quantity of hot water and are therefore provided with industrial water heaters having a hot water reservoir.
To supply the water from the reservoir to the outer tube 16 of the heat exchanger 10, a pump, having an inlet connected to the reservoir, has an outlet connected to the inlet 24 of the outer tube 16.
The outlet 26 of the outer tube 16 is connected to the reservoir to thereby discharge the water back into it.
A relative vacuum level of about 760 mm of mercury is obtained in the vacuum chamber 14 by drawing the air from the chamber 14 through the air outlet 20 with a vacuum pump (not shown). After the above mentioned vacuum level is reached, a valve (not shown) may be closed to seal the air outlet 20 and the vacuum pump removed from the air outlet 20.
The water pumped through the outer tube 16 is therefore heated by the hot gases of the refrigeration system.
Of course, the temperature difference between the water at the inlet 24 of the outer tube 16 and the water at the outlet 26 of the inner tube 16 depends on many factors. The length of the inner and outer tubes 16 and 18, the temperature of the hot gases and the initial temperature of the water in the reservoir are factors that affect the above mentioned temperature difference.
It is to be noted that, since the same water may be cycled in the heat exchanger, obtaining a temperature of the water in the reservoir that is 2 1 70 1 q7 similar to the temperature obtained with conventional electrical heating elements is possible.
It is believed that, since the temperature of the water entering the heat exchanger 10 through the inlet 24 increases with time (if no water is retrieved from the reservoir), the vacuum chamber 14 increases the efficiency of the heat exchanger since there is no heat loss to the ambient air and the boiling point of water is decreased.
Turning now to Figure 4 of the appended drawings, a heat exchanger 100 according to a second preferred embodiment of the present invention will be described.
A major difference between the heat exchanger 100 and the heat exchanger 10 of Figures 1-3 is that the inner tube 18 exits the outer tube 16 at each curve of the multiple "S" shape of the outer tube 16.
As illustrated in this figure, assembling the heat exchanger 100 by using conventional elbows 102 and modified elbows 104 is possible. The elbows 104 are provided with an aperture 106 to allow the inner tube 18 to exit through the elbows 104. Of -course, leaks are prevented by soldering the inner tube 18 to the aperture 106 (see 108).
This characteristic presents a major advantage for the construction of the heat exchanger 100 since it is not required to bend two concentric tubes simultaneously, which may require specialized tools and/or machinery. It is therefore possible to assemble the heat exchanger 100 with simple conventional tools.
The other characteristics of the heat exchanger 100 are similar to the characteristics of the heat exchanger 10.
As will be apparent to one of ordinary skills in the art, the flow of the cold and hot fluids in the inner and outer tubes could be in the same direction.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.
VACWM CHAMBERED HEAT EXCHANGER
FIELD OF THE lNV~NllON
The present invention relates to heat exchangers. More particularly, the present invention relates to heat exchangers adapted to heat or to cool flowable or pumpable mediums.
R~C~ROUND OF THE lNV~N-llON
The prior art is replete with heat exchangers consisting of a first tube inserted in a second tube and in which a hot fluid is introduced in the first tube and a cold fluid is introduced in the second tube. The purpose of these heat exchangers is to increase the temperature of the cold fluid of the second tube or to decrease the temperature of the hot fluid of the first tube. However, in both cases, the physical effect is a transfer of heat from the hot .
fluid to the cold fluid to cool the hot fluid and to heat the cool fluid.
For example, U.S. Patent N 4,554,969 issued on November 26, 1985 to Carnavos describes a coaxial finned tube heat exchanger having an inner tube and an outer tube.
U.S. Patent N4,893,670 issued on January 16, 1990 to Joshi et al. describes a heat exchanger combining an oil cooler and a radiator hose. This heat exchanger comprises two generally concentric hoses provided with internal deflectable vanes. In this case, the hot fluid (the oil) is supplied to the external hose while the cold fluid (the engine coolant) is supplied to the internal hose.
A drawback of the above discussed heat exchangers is their relatively poor efficiency when the amount of heat to be recuperated from a hot fluid and transferred to a cold fluid is substantial.
Indeed, the fluid introduced in the outer tube of conventional heat exchangers has intimate contact with the air surrounding this outer tube. Since this air is usually at a lower temperature with respect to the temperature of the fluid introduced in the outer tube, part of the heat of this fluid is transferred to the air, therefore reducing the overall efficiency of the 21 701 ~7 heat exchanger. The efficiency of conventional heat exchangers therefore decreases with the increase of the temperature of the fluid of the outer tube.
OBJECTS OF THE lNV~;N-l lON
An object of the present invention is therefore to provide an improved efficiency heat exchanger.
Another object of the invention is to provide a heat exchanger at least partially enclosed in a vacuum chamber to thereby insulate the heat exchanger from the external environment.
SU~ARY OF THE lNv~ LloN
More specifically, in accordance with the present invention, there is provided a heat exchanger for exchanging heat between a first and second medium having respective flow rates; the heat exchanger comprises:
a) a first tube for receiving the first medium, the first tube having first and second ends 2] 701 ~7 respectively providing first medium inlet and first medium outlet, the first tube also having an outer wall;
b) a second tube for receiving the second medium, the second tube having first and second ends respectively providing second medium inlet and second medium outlet, the second tube also having an inner wall; the second tube being in close contact with the first tube to enable heat exchange between the first 0 medium and the second medium; and c) a vacuum chamber enclosing at least a portion of the first and second tubes;
whereby, the exchange of heat between the first and second mediums is improved by a vacuum provided in the vacuum chamber, thereby increasing the efficiency of the heat exchanger.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.
21 701 ~7 BRIEF DESCRIPTION OF THE DRAWINGS
In the appended drawings:
Figure 1 illustrates a side elevational view, partially in section, of a heat exchanger according to a first embodiment of the present invention;
Figure 2 is a sectional view taken along line 2-2 of Figure 1;
Figure 3 is a sectional view taken along line 3-3 of Figure 2; and Figure 4 illustrates a side elevational view, partially in section, of a heat exchanger according to a second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It is to be noted that the terms "hot" and "cold" are relative and used herein to generally 2170~q7 describe the temperature of the fluids. More specifically, the term "hot fluid" means than the fluid is at a higher temperature than the "cold fluid", and vice-versa. Furthermore, the term "fluid"
is used herein to describe any gaseous, liquid or semi-liquid flowable and pumpable mediums.
It has been found that by enclosing a heat exchanger in an enclosure held under a partial vacuum (this enclosure will hereinafter be referred to as the vacuum chamber), it is possible to increase the overall efficiency of the heat exchanger.
Two physical properties may be considered to explain the increase in efficiency of a heat exchanger enclosed in a vacuum chamber. First, the vacuum chamber insulates the heat exchanger from the external environment, which ensures that no heat is ~lost" to the ambient air. Second, since the boiling point of the fluids in the heat exchanger is reduced by the reduction of air pressure, it is believed that the transfer of heat is eased.
Turning now to Figures 1-3 of the appended drawings, a heat exchanger 10 according to a first embodiment of the present invention will be described.
2 1 70 1 q7 The heat exchanger 10 includes an enclosure 12 defining a chamber 14, an outer tube 16, an inner tube 18, an air outlet 20 and an air pressure meter 22.
As illustrated in Figure 1, the inner tube 18 is inserted in the outer tube 16 and these tubes describe a multiple "Sn shape. Of course, this multiple "S" shape is intended to reduce the space required for the heat exchanger 10 and to slow the flows of fluid therein to thereby increase the residence time of the fluids in the outer and inner tubes 16 and 18.
The outer tube 16 includes a fluid inlet 24 and a fluid outlet 26 having a cross sectional area larger than the fluid inlet 24 as explained hereinafter.
The inner tube 18 includes a fluid inlet 28 and a fluid outlet 30.
The inner tube 18 has a first angled portion 34 near the outlet 32 and enters the outer 25 tube 16 through an aperture 36 provided near the inlet 24.
Similarly, the inner tube 18 has a second angled portion 38 near the inlet 30 and enters the outer tube 16 through an aperture 40 provided near the outlet 24.
Therefore, a significant portion of the inner tube 18 is enclosed in the outer tube 16.
A source of hot fluid (not shown) may be connected between the inlet 30 and the outlet 32 of the inner tube 18 therefore to supply the heat exchanger 10 with hot fluid (see arrows 42 and 44).
Similarly, a source of cold fluid (not shown) may be connected between the inlet 24 and the outlet 26 of 15 the outer tube 16 therefore to supply the heat exchanger 10 with cold fluid (see arrows 46 and 48) .
Heat will therefore be transferred from the hot fluid to the cold fluid, thereby cooling said 20 hot fluid and heating said cold fluid.
Turning to Figure 2, the inner tube 18 also includes a plurality of wings 50 mounted on its outer wall. These wings define an acute angle with 25 respect to the direction of the flow of the cold fluid (see arrow 52), thereby decreasing the flow rate of the cold fluid. This characteristic has a direct effect on the period of residence of the cold fluid in the heat exchanger 10 since the decrease of the flow rate increases the period of residence of the cold fluid in the outer tube 16, thereby improving the heat transfer between the hot and cold fluids by keeping them in contact a longer period.
As illustrated in Figure 3, the wings 50 are circumferentially disposed around said inner tube 18 while providing gaps 54. Of course, the wings 50 could be replaced by other types of flow decreasing members such as fins, ribs, or the like. It has however been found that wings 50 having an acute angle with respect to the direction of flow of the cold fluid operate in a satisfactory manner.
As will be easily understood to one of ordinary skills in the art, since the flow rate of the cold fluid is decreased by the wings 50, the area of the outlet 26 of the cold fluid must be increased since the flow of cold fluid entering through the inlet 24 and the flow of cold fluid exiting through the outlet 26 is identical and that the flow rate is decreased.
The enclosure 12 is substantially airtight to enable the creation of a partial vacuum in the chamber 14. The air outlet 20 may be connected to a vacuum pump (not shown) to thereby draw the air ~ 21 701 97 present in the enclosure. The meter 22 indicates the air pressure level in the chamber 14. A valve (not shown) may be provided to close the air outlet 20 when a predetermined vacuum level is reached.
The operation of the heat exchanger 10 will be described by the way of the following non limitative example of installation of a heat exchanger in an industrial facility.
A heat exchanger similar to the heat exchanger 10 has been installed in an industrial abattoir requiring a substantial amount of hot water and having a plurality of freezers using conventional refrigeration systems. The purpose of this installation was to use the excess heat generated by the refrigeration systems to efficiently heat the water to a sufficient temperature so as to eliminate the need for conventional electrical heating elements in the water heaters.
As will be evident to one of ordinary skills in the art of refrigerating systems, the compressor used to refrigerate a freezer, or the like, generally use a radiator to cool the gases having absorbed heat in the freezer.
To use a portion of this heat present in the hot gases of the refrigeration system, the inner tube 18 of the heat exchanger 10 has been inserted in parallel with the above mentioned radiator to thereby receive a predetermined and variable portion of the hot gases exiting the compressor. These hot gases enter the inner tube 18 through the hot fluid inlet 30 and exit the inner tube 18 through the hot fluid outlet 32.
As will be obvious to one of ordinary skills in the art, sufficient heat must remain in the hot gases returning to the refrigeration system for adequate operation of the refrigeration system. It is therefore advantageous to supply only a portion of the hot gases to the inner tube 18 of the heat exchanger 10 .
As previously mentioned industrial abattoirs use a substantial quantity of hot water and are therefore provided with industrial water heaters having a hot water reservoir.
To supply the water from the reservoir to the outer tube 16 of the heat exchanger 10, a pump, having an inlet connected to the reservoir, has an outlet connected to the inlet 24 of the outer tube 16.
The outlet 26 of the outer tube 16 is connected to the reservoir to thereby discharge the water back into it.
A relative vacuum level of about 760 mm of mercury is obtained in the vacuum chamber 14 by drawing the air from the chamber 14 through the air outlet 20 with a vacuum pump (not shown). After the above mentioned vacuum level is reached, a valve (not shown) may be closed to seal the air outlet 20 and the vacuum pump removed from the air outlet 20.
The water pumped through the outer tube 16 is therefore heated by the hot gases of the refrigeration system.
Of course, the temperature difference between the water at the inlet 24 of the outer tube 16 and the water at the outlet 26 of the inner tube 16 depends on many factors. The length of the inner and outer tubes 16 and 18, the temperature of the hot gases and the initial temperature of the water in the reservoir are factors that affect the above mentioned temperature difference.
It is to be noted that, since the same water may be cycled in the heat exchanger, obtaining a temperature of the water in the reservoir that is 2 1 70 1 q7 similar to the temperature obtained with conventional electrical heating elements is possible.
It is believed that, since the temperature of the water entering the heat exchanger 10 through the inlet 24 increases with time (if no water is retrieved from the reservoir), the vacuum chamber 14 increases the efficiency of the heat exchanger since there is no heat loss to the ambient air and the boiling point of water is decreased.
Turning now to Figure 4 of the appended drawings, a heat exchanger 100 according to a second preferred embodiment of the present invention will be described.
A major difference between the heat exchanger 100 and the heat exchanger 10 of Figures 1-3 is that the inner tube 18 exits the outer tube 16 at each curve of the multiple "S" shape of the outer tube 16.
As illustrated in this figure, assembling the heat exchanger 100 by using conventional elbows 102 and modified elbows 104 is possible. The elbows 104 are provided with an aperture 106 to allow the inner tube 18 to exit through the elbows 104. Of -course, leaks are prevented by soldering the inner tube 18 to the aperture 106 (see 108).
This characteristic presents a major advantage for the construction of the heat exchanger 100 since it is not required to bend two concentric tubes simultaneously, which may require specialized tools and/or machinery. It is therefore possible to assemble the heat exchanger 100 with simple conventional tools.
The other characteristics of the heat exchanger 100 are similar to the characteristics of the heat exchanger 10.
As will be apparent to one of ordinary skills in the art, the flow of the cold and hot fluids in the inner and outer tubes could be in the same direction.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit and nature of the subject invention as defined in the appended claims.
Claims (20)
1 . A heat exchanger for exchanging heat between a first and second medium having respective flow rates, said heat exchanger comprising:
a) a first tube for receiving said first medium, said first tube having first and second ends respectively providing first medium inlet and first medium outlet, said first tube having an outer wall;
b) a second tube for receiving said second medium, said second tube having first and second ends respectively providing second medium inlet and second medium outlet, said second tube having an inner wall;
said second tube being in close contact with said first tube to enable heat exchange between said first medium and said second medium; and c) a vacuum chamber enclosing at least a portion of said first and second tubes;
whereby said exchange of heat between said first and second mediums is augmented by a vacuum provided in said vacuum chamber, to thereby increase the efficiency of said heat exchanger.
a) a first tube for receiving said first medium, said first tube having first and second ends respectively providing first medium inlet and first medium outlet, said first tube having an outer wall;
b) a second tube for receiving said second medium, said second tube having first and second ends respectively providing second medium inlet and second medium outlet, said second tube having an inner wall;
said second tube being in close contact with said first tube to enable heat exchange between said first medium and said second medium; and c) a vacuum chamber enclosing at least a portion of said first and second tubes;
whereby said exchange of heat between said first and second mediums is augmented by a vacuum provided in said vacuum chamber, to thereby increase the efficiency of said heat exchanger.
2. The heat exchanger of claim 1, wherein at least a portion of said first tube is housed inside said second tube.
3. The heat exchanger of claim 2, further comprising flow rate decreasing means mounted to one of said first and second tubes for decreasing the flow rate of said second medium to thereby increase a residence period of said second medium in said second tube and augment the efficiency of said heat exchanger.
4. The heat exchanger of claim 3, wherein said flow rate decreasing means include wing members mounted to at least one of said outer wall of said first tube and inner wall of said second tube.
5. The heat exchanger of claim 4, wherein said wing members are mounted at an acute angle with respect to a direction of flow of said second medium in said second tube.
6. The heat exchanger of claim 2, wherein said first and second tubes are concentric.
7. The heat exchanger of claim 1, wherein said first medium flows in said first tube in a direction which is opposite to that of said second medium in said second tube.
8. The heat exchanger of claim 2, wherein said second tube defines at least one S shape, thereby minimizing the space taken by said second tube and increasing the residence time of said first and second medium inside said first and second tubes.
9. The heat exchanger of claim 1, wherein said first and second mediums are selected from the group consisting of a gas, a liquid and a semi-solid flowable medium.
10. The heat exchanger of claim 5, wherein said first medium comprises a hot gas and said second medium comprises a cold liquid.
11. The heat exchanger of claim 3, wherein said second medium outlet has a cross sectional area substantially larger than a cross sectional area of said second medium inlet.
12. The heat exchanger of claim 1, wherein a relative vacuum level of approximately 760 mm of mercury is provided in said vacuum chamber.
13. A heat exchanger for exchanging heat between a first and second medium comprising:
a) a first tube for receiving said first medium, said first tube having first and second ends respectively providing first medium inlet and first medium outlet, said first tube having an outer wall;
b) a second tube for receiving said second medium, said second tube having first and second ends respectively providing second medium inlet and second medium outlet, said second tube having an inner wall;
said second tube being housed inside said first tube, thereby enabling heat exchange between said first medium and said second medium; and c) a vacuum chamber enclosing at least a portion of said first and second tubes;
whereby said exchange of heat between said first and second mediums is augmented by a vacuum provided in said vacuum chamber to thereby increase the efficiency of said heat exchanger.
a) a first tube for receiving said first medium, said first tube having first and second ends respectively providing first medium inlet and first medium outlet, said first tube having an outer wall;
b) a second tube for receiving said second medium, said second tube having first and second ends respectively providing second medium inlet and second medium outlet, said second tube having an inner wall;
said second tube being housed inside said first tube, thereby enabling heat exchange between said first medium and said second medium; and c) a vacuum chamber enclosing at least a portion of said first and second tubes;
whereby said exchange of heat between said first and second mediums is augmented by a vacuum provided in said vacuum chamber to thereby increase the efficiency of said heat exchanger.
14. The heat exchanger of claim 13, wherein said first medium flows inside said first tube in one direction and said second medium flows inside said second tube in an opposite direction relative to said direction of said first medium.
15. The heat exchanger of claim 14, wherein at least one of said outer wall of said first tube and said inner wall of said second tube is provided with wing members, said wing members being at an acute angle relative to said direction of flow of said second medium, thereby increasing a residence period of said second medium in said second tube and increasing the efficiency of said heat exchanger.
16. The heat exchanger of claim 13, wherein, said first and second mediums are selected from the group consisting of a gas, a liquid and a semi-solid flowable medium.
17. The heat exchanger of claim 15, wherein said second medium outlet has a cross sectional area substantially larger than that of said second medium inlet.
18. The heat exchanger of claim 16, wherein said first medium comprises a relatively hot gas and said second medium comprises a relatively cold liquid.
19. The heat exchanger of claim 18, wherein said first and second tube define at least one S shape, thereby minimizing the space taken by said second tube and increasing the residence time of said hot gas and said cold liquid in said first and second tubes, respectively.
20. The heat exchanger of claim 19, wherein said first tube includes a plurality of first elbows forming said at least on S shape of said first tube and wherein said second tube includes a plurality of second elbows forming said at least on S shape of said second tube; said second elbows defining an aperture adapted to allow passage of said first tube therethrough.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002170197A CA2170197A1 (en) | 1996-02-23 | 1996-02-23 | Vacuum chambered heat exchanger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002170197A CA2170197A1 (en) | 1996-02-23 | 1996-02-23 | Vacuum chambered heat exchanger |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2170197A1 true CA2170197A1 (en) | 1997-08-24 |
Family
ID=4157623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002170197A Abandoned CA2170197A1 (en) | 1996-02-23 | 1996-02-23 | Vacuum chambered heat exchanger |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2170197A1 (en) |
-
1996
- 1996-02-23 CA CA002170197A patent/CA2170197A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |