CA2481477C - Loop-type thermosiphon and stirling refrigerator - Google Patents
Loop-type thermosiphon and stirling refrigerator Download PDFInfo
- Publication number
- CA2481477C CA2481477C CA2481477A CA2481477A CA2481477C CA 2481477 C CA2481477 C CA 2481477C CA 2481477 A CA2481477 A CA 2481477A CA 2481477 A CA2481477 A CA 2481477A CA 2481477 C CA2481477 C CA 2481477C
- Authority
- CA
- Canada
- Prior art keywords
- evaporator
- heat
- working fluid
- loop
- temperature
- 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.)
- Expired - Fee Related
Links
- 239000012530 fluid Substances 0.000 claims abstract description 68
- 239000007788 liquid Substances 0.000 claims abstract description 60
- 238000010521 absorption reaction Methods 0.000 claims abstract description 27
- 238000001704 evaporation Methods 0.000 claims abstract description 11
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 238000001816 cooling Methods 0.000 description 15
- 239000003507 refrigerant Substances 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 229910001868 water Inorganic materials 0.000 description 12
- 239000007789 gas Substances 0.000 description 11
- 230000017525 heat dissipation Effects 0.000 description 11
- 230000005484 gravity Effects 0.000 description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 8
- 238000000926 separation method Methods 0.000 description 8
- 230000008020 evaporation Effects 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000011089 carbon dioxide Nutrition 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 230000003389 potentiating effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013526 supercooled liquid Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B25/00—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00
- F25B25/005—Machines, plants or systems, using a combination of modes of operation covered by two or more of the groups F25B1/00 - F25B23/00 using primary and secondary systems
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D11/00—Self-contained movable devices, e.g. domestic refrigerators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0266—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with separate evaporating and condensing chambers connected by at least one conduit; Loop-type heat pipes; with multiple or common evaporating or condensing chambers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B23/00—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect
- F25B23/006—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect boiling cooling systems
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D23/00—General constructional features
- F25D23/003—General constructional features for cooling refrigerating machinery
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Devices That Are Associated With Refrigeration Equipment (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
- Sorption Type Refrigeration Machines (AREA)
Abstract
A loop-type thermosiphon capable of stable operation regardless of fluctuation of heat load and a Stirling refrigerator using the same are provided. The loop-type thermosiphon transferring heat from a high-temperature heat source using a working fluid includes a evaporator having a heat absorption portion and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion, a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator, and a pipe connecting the evaporator and the condenser so as to form a loop. In the loop-type thermosiphon, the working fluid that has passed through the condenser is brought in contact with the heat absorption portion before it is pooled in a liquid pool for the working fluid in the evaporator, so as to exchange heat with the same.
Description
Loop-Type Thermosiphon and Stirling Refrigerator Field of the Invention The present invention relates to a loop-type thermosiphon and a Stirling refrigerator using the same.
Background of the Invention A heat sink, a heat pipe, a thermosiphon, or the like is used for cooling a heat-generating instrument or a thermoelectric cooling device. As for the heat sink, temperature distribution is caused in a base portion thereof provided with a heat source. Accordingly, as the distance from the heat source is increased, the heat sink contributes less to heat dissipation. Meanwhile, the heat pipe or the thermosiphon has high heat transfer capability, and is characterized by small temperature variation even when the heat is transferred to a portion distant from the heat source.
On the other hand, with regard to the heat pipe, vapor and liquid of a working fluid flows in the same pipe. As such, if an amount of heat transfer is large, a greater number of pipes are necessary. For example, if it is assumed that the temperature difference is set to 5 C, a heat pipe having an outer diameter of 15.8mm and a length of 300mm attains an amount of heat transfer of approximately 100W. If the heat should be ultimately emitted to an atmospheric environment, a heat pipe including a condensation portion having a large heat transfer area should be provided in order to exchange heat with air, because the heat transfer coefficient of the air is low. A pipe-shaped thermosiphon in which a liquid returns to an evaporation portion by gravity also has similar characteristics.
Meanwhile, a loop-type thermosiphon is also structured such that the liquid condensed in a condenser returns to an evaporator by gravity. Here, however, not only the shape and the size of the condenser can be designed in accordance with cooling means of the condenser, but also the evaporator can be designed in accordance with the shape and the size of the heat source. Therefore, two pipes, such as, a gas pipe and a liquid pipe connecting the condenser and the evaporator are enough in most cases. Here, it is natural that the condenser has to be located above the evaporator.
In the loop-type thermosiphon, however, circulation flow rate is less likely to be stabilized and the temperature of the heat source tends to fluctuate in many cases, depending on the type of the contained working fluid or heat load fluctuation in a certain range. As is well-known, a CFC (chiorofluorocarbon) and an HCFC-based refrigerant have been used as a working fluid or as a secondary working fluid in cooling equipment. The CFC-based refrigerant, however, is no longer used, and the use of HCFC-based refrigerants are restricted under international treaties for protecting ozone layer. In addition, a newly developed HFC-based refrigerant, though not destroying the ozone layer, is a potent greenhouse substance attaining a global warming coefficient several hundred to several thousand or more times larger than carbon dioxide, and subject to effluent control. Therefore, types of refrigerants that can be selected as a working fluid for the loop-type thermosiphon are limited from the viewpoint of environmental protection. Examples of environmental-friendly and what is called natural refrigerants include medium such as an HC-based refrigerant, ammonia, carbon dioxide, water, and ethanol, and a mixture thereof.
Japanese Patent Laying-Open No. 11-223404 discloses a method of cooling the high-temperature portion of a Stirling cooler with a liquid of a secondary refrigerant by means of a pump.
In the conventional loop-type thermosiphon, however, unstable circulation flow rate of the working fluid has been likely, resulting in fluctuation of the temperature of the heat source. In particular, if the conventional loop-type thermosiphon is operated under a load far from the target load in accordance with design, the temperature of the heat source often fluctuates significantly. If the temperature of the heat source fluctuates significantly, not only with the performance of heat source equipment become unstable, but also the heat source equipment may be damaged.
Here, it is assumed that the loop-type thermosiphon is utilized for cooling the high-temperature portion of a Stirling cooler and the Stirling cooler is mounted on a refrigerator, for example. As is well-known, the heat load of the refrigerator fluctuates depending on the season. When the heat load of the refrigerator fluctuates, the amount of heat dissipation from the high-temperature portion of the Stirling cooler also varies. The loop-type thermosiphon often exhibits unstable operation under fluctuating heat load. Here, if the temperature of the high-temperature portion of the Stirling cooler fluctuates significantly, the influence therefrom is not limited to fluctuation of a COP (Coefficient of Performance) of the Stirling cooler. If the temperature of the high-temperature portion is excessively high, the regenerator of the Stirling cooler may be destroyed.
Summary of the Invention An object of the present invention is to provide a loop-type thermosiphon capable of maintaining a stable temperature of a high-temperature heat source in spite of large fluctuation of heat load and a Stirling refrigerator equipped with the same.
In accordance with an aspect of the present invention, there is provided a loop-type thermosiphon for transferring heat from a cylindrical high-temperature heat source having a cylindrical heat dissipation surface and extending in a horizontal direction using a working fluid, comprising an evaporator having a heat absorption portion attached to the heat dissipation surface of the high-temperature heat source and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion; a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator; and a gas pipe and a liquid pipe connecting the evaporator and the condenser so as to form a loop; wherein an outlet of the liquid pipe is positioned adjacent to a top portion of the heat absorption portion that the working fluid, that has passed through the condenser and has been condensed is dropped, on the top portion of the heat absorption portion.
A loop-type thermosiphon according to the present invention transfers heat from a cylindrical high-temperature heat source using a working fluid. The loop-type thermosiphon includes: an annular evaporator having a heat absorption portion attached to the high-temperature heat source and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion; a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator; and a pipe connecting the evaporator and the condenser so as to form a loop. The working fluid that has passed through the condenser and has been condensed is made to fall on the heat absorption portion.
Background of the Invention A heat sink, a heat pipe, a thermosiphon, or the like is used for cooling a heat-generating instrument or a thermoelectric cooling device. As for the heat sink, temperature distribution is caused in a base portion thereof provided with a heat source. Accordingly, as the distance from the heat source is increased, the heat sink contributes less to heat dissipation. Meanwhile, the heat pipe or the thermosiphon has high heat transfer capability, and is characterized by small temperature variation even when the heat is transferred to a portion distant from the heat source.
On the other hand, with regard to the heat pipe, vapor and liquid of a working fluid flows in the same pipe. As such, if an amount of heat transfer is large, a greater number of pipes are necessary. For example, if it is assumed that the temperature difference is set to 5 C, a heat pipe having an outer diameter of 15.8mm and a length of 300mm attains an amount of heat transfer of approximately 100W. If the heat should be ultimately emitted to an atmospheric environment, a heat pipe including a condensation portion having a large heat transfer area should be provided in order to exchange heat with air, because the heat transfer coefficient of the air is low. A pipe-shaped thermosiphon in which a liquid returns to an evaporation portion by gravity also has similar characteristics.
Meanwhile, a loop-type thermosiphon is also structured such that the liquid condensed in a condenser returns to an evaporator by gravity. Here, however, not only the shape and the size of the condenser can be designed in accordance with cooling means of the condenser, but also the evaporator can be designed in accordance with the shape and the size of the heat source. Therefore, two pipes, such as, a gas pipe and a liquid pipe connecting the condenser and the evaporator are enough in most cases. Here, it is natural that the condenser has to be located above the evaporator.
In the loop-type thermosiphon, however, circulation flow rate is less likely to be stabilized and the temperature of the heat source tends to fluctuate in many cases, depending on the type of the contained working fluid or heat load fluctuation in a certain range. As is well-known, a CFC (chiorofluorocarbon) and an HCFC-based refrigerant have been used as a working fluid or as a secondary working fluid in cooling equipment. The CFC-based refrigerant, however, is no longer used, and the use of HCFC-based refrigerants are restricted under international treaties for protecting ozone layer. In addition, a newly developed HFC-based refrigerant, though not destroying the ozone layer, is a potent greenhouse substance attaining a global warming coefficient several hundred to several thousand or more times larger than carbon dioxide, and subject to effluent control. Therefore, types of refrigerants that can be selected as a working fluid for the loop-type thermosiphon are limited from the viewpoint of environmental protection. Examples of environmental-friendly and what is called natural refrigerants include medium such as an HC-based refrigerant, ammonia, carbon dioxide, water, and ethanol, and a mixture thereof.
Japanese Patent Laying-Open No. 11-223404 discloses a method of cooling the high-temperature portion of a Stirling cooler with a liquid of a secondary refrigerant by means of a pump.
In the conventional loop-type thermosiphon, however, unstable circulation flow rate of the working fluid has been likely, resulting in fluctuation of the temperature of the heat source. In particular, if the conventional loop-type thermosiphon is operated under a load far from the target load in accordance with design, the temperature of the heat source often fluctuates significantly. If the temperature of the heat source fluctuates significantly, not only with the performance of heat source equipment become unstable, but also the heat source equipment may be damaged.
Here, it is assumed that the loop-type thermosiphon is utilized for cooling the high-temperature portion of a Stirling cooler and the Stirling cooler is mounted on a refrigerator, for example. As is well-known, the heat load of the refrigerator fluctuates depending on the season. When the heat load of the refrigerator fluctuates, the amount of heat dissipation from the high-temperature portion of the Stirling cooler also varies. The loop-type thermosiphon often exhibits unstable operation under fluctuating heat load. Here, if the temperature of the high-temperature portion of the Stirling cooler fluctuates significantly, the influence therefrom is not limited to fluctuation of a COP (Coefficient of Performance) of the Stirling cooler. If the temperature of the high-temperature portion is excessively high, the regenerator of the Stirling cooler may be destroyed.
Summary of the Invention An object of the present invention is to provide a loop-type thermosiphon capable of maintaining a stable temperature of a high-temperature heat source in spite of large fluctuation of heat load and a Stirling refrigerator equipped with the same.
In accordance with an aspect of the present invention, there is provided a loop-type thermosiphon for transferring heat from a cylindrical high-temperature heat source having a cylindrical heat dissipation surface and extending in a horizontal direction using a working fluid, comprising an evaporator having a heat absorption portion attached to the heat dissipation surface of the high-temperature heat source and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion; a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator; and a gas pipe and a liquid pipe connecting the evaporator and the condenser so as to form a loop; wherein an outlet of the liquid pipe is positioned adjacent to a top portion of the heat absorption portion that the working fluid, that has passed through the condenser and has been condensed is dropped, on the top portion of the heat absorption portion.
A loop-type thermosiphon according to the present invention transfers heat from a cylindrical high-temperature heat source using a working fluid. The loop-type thermosiphon includes: an annular evaporator having a heat absorption portion attached to the high-temperature heat source and evaporating the working fluid by depriving the high-temperature heat source of heat through the heat absorption portion; a condenser located above the high-temperature heat source and condensing the working fluid that has evaporated in the evaporator; and a pipe connecting the evaporator and the condenser so as to form a loop. The working fluid that has passed through the condenser and has been condensed is made to fall on the heat absorption portion.
According to such an arrangement, the cooled and condensed working fluid is preheated after falling on the heat absorption portion instead of being directly supplied to the liquid pool, and thereafter it is supplied from above by gravity.
Accordingly, a flow is produced in the liquid pool and evaporation of the working fluid as a whole, including the working fluid in the liquid pool, is promoted.
Naturally, evaporation of the working fluid that has been introduced and initially exchanges heat with the heat absorption portion is also promoted in an ensured manner, whereby temperature distribution in the high-temperature heat source can be uniform.
In addition, separation of bubbles adhered to the heat absorption portion or the like can be promoted. Therefore, heat exchange adapted to fluctuation of the heat load can be performed, and the temperature of the high-temperature heat source can be stabilized. In addition, as the high-temperature heat source has a cylindrical shape and the evaporator has an annular shape, an apparatus having a compact structure and ensuring heat exchange efficiency can readily be manufactured.
Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of example, in conjunction with the following drawings, in which:
Fig. 1 illustrates a basic arrangement of a loop-type thermosiphon in a first embodiment of the present invention;
Fig. 2 shows a variation of the loop-type thermosiphon in the first embodiment of the present invention;
Fig. 3 shows a Stirling refrigerator in a second embodiment of the present invention;
Fig. 4 shows stability of a temperature of a heat source when a loop-type thermosiphon in a third embodiment of the present invention is employed;
Fig. 5 shows an arrangement of a general loop-type thermosiphon;
Fig. 6 shows an evaporator in a conventional loop-type thermosiphon; and Fig. 7 shows fluctuation of a temperature of a heat source when the conventional loop-type thermosiphon is used.
Accordingly, a flow is produced in the liquid pool and evaporation of the working fluid as a whole, including the working fluid in the liquid pool, is promoted.
Naturally, evaporation of the working fluid that has been introduced and initially exchanges heat with the heat absorption portion is also promoted in an ensured manner, whereby temperature distribution in the high-temperature heat source can be uniform.
In addition, separation of bubbles adhered to the heat absorption portion or the like can be promoted. Therefore, heat exchange adapted to fluctuation of the heat load can be performed, and the temperature of the high-temperature heat source can be stabilized. In addition, as the high-temperature heat source has a cylindrical shape and the evaporator has an annular shape, an apparatus having a compact structure and ensuring heat exchange efficiency can readily be manufactured.
Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of example, in conjunction with the following drawings, in which:
Fig. 1 illustrates a basic arrangement of a loop-type thermosiphon in a first embodiment of the present invention;
Fig. 2 shows a variation of the loop-type thermosiphon in the first embodiment of the present invention;
Fig. 3 shows a Stirling refrigerator in a second embodiment of the present invention;
Fig. 4 shows stability of a temperature of a heat source when a loop-type thermosiphon in a third embodiment of the present invention is employed;
Fig. 5 shows an arrangement of a general loop-type thermosiphon;
Fig. 6 shows an evaporator in a conventional loop-type thermosiphon; and Fig. 7 shows fluctuation of a temperature of a heat source when the conventional loop-type thermosiphon is used.
Detailed Description of the Invention Shown in Fig. 5, is a conventional loop-type thermosiphon which is structured by connecting an evaporator 101, a condenser 103 and a gas-liquid separation tank 106 using pipes 102, 104. A heat source 105 is cooled in evaporator 101.
Condenser 103 is provided above evaporator 101. The working fluid liquefied in condenser 103 is separated into gas and liquid in the gas-liquid, separation tank 106 provided between the condenser 103 and the evaporator 101. The liquid of the working fluid transverses pipe 104 by gravity, and is introduced in the evaporator 101 at a position in the lower portion of evaporator 101. In addition, the working fluid that has deprived the heat source of heat is vaporized in evaporator 101, and the vapor of the working fluid is introduced into condenser 103 through pipe 102 by a vapor pressure difference between the condenser 103 and the evaporator 101. In most cases, evaporator 101 is designed in accordance with the shape of the heat source.
In Fig. 5, gas-liquid separation tank 106 is not essential.
Fig. 6 shows an evaporator for cooling the heat source of a conventional loop-type thermosiphon having a cylindrical shape. Evaporator 101 has an annular shape in order to cool cylindrical heat source 105. Cylindrical heat source 105 is fitted in a hole of the evaporator 101, so as to be in close contact with a surface of the hole of the evaporator 101. The surface of the hole of the evaporator 101 is provided with an internal fin (not shown) for increasing the evaporation area. Liquid from the condenser runs through pipe 104 and flows into a liquid pool 121 through a lower portion of the evaporator 101, and the vapor exits from an upper portion of the evaporator 101 through pipe 102 and flows to the condenser.
Fig. 7 shows the temperature variation of the heat source variation in an experimental operation of the loop-type thermosiphon employing the evaporator and the pipe arrangement shown in Fig. 6 and containing water as the working fluid. If amount of heat generation from the heat source is not larger than 75% of the designed load, fluctuation in the temperature of the heat source results, as shown in Fig. 7. Improvement was not observed even when a contained amount of the working fluid was changed.
In the following, embodiments of the present invention will be described with reference to the figures.
Condenser 103 is provided above evaporator 101. The working fluid liquefied in condenser 103 is separated into gas and liquid in the gas-liquid, separation tank 106 provided between the condenser 103 and the evaporator 101. The liquid of the working fluid transverses pipe 104 by gravity, and is introduced in the evaporator 101 at a position in the lower portion of evaporator 101. In addition, the working fluid that has deprived the heat source of heat is vaporized in evaporator 101, and the vapor of the working fluid is introduced into condenser 103 through pipe 102 by a vapor pressure difference between the condenser 103 and the evaporator 101. In most cases, evaporator 101 is designed in accordance with the shape of the heat source.
In Fig. 5, gas-liquid separation tank 106 is not essential.
Fig. 6 shows an evaporator for cooling the heat source of a conventional loop-type thermosiphon having a cylindrical shape. Evaporator 101 has an annular shape in order to cool cylindrical heat source 105. Cylindrical heat source 105 is fitted in a hole of the evaporator 101, so as to be in close contact with a surface of the hole of the evaporator 101. The surface of the hole of the evaporator 101 is provided with an internal fin (not shown) for increasing the evaporation area. Liquid from the condenser runs through pipe 104 and flows into a liquid pool 121 through a lower portion of the evaporator 101, and the vapor exits from an upper portion of the evaporator 101 through pipe 102 and flows to the condenser.
Fig. 7 shows the temperature variation of the heat source variation in an experimental operation of the loop-type thermosiphon employing the evaporator and the pipe arrangement shown in Fig. 6 and containing water as the working fluid. If amount of heat generation from the heat source is not larger than 75% of the designed load, fluctuation in the temperature of the heat source results, as shown in Fig. 7. Improvement was not observed even when a contained amount of the working fluid was changed.
In the following, embodiments of the present invention will be described with reference to the figures.
Fig. 1 is a conceptual diagram illustrating the basic arrangement of the loop-type thermosiphon according to a first embodiment of the present invention.
The loop-type thermosiphon shown in Fig. 1 is constituted of an evaporator 1, a condenser 3, a gas pipe 2 extending from evaporator 1 to condenser 3, and a liquid pipe 4 extending from condenser 3 to evaporator 1. In the present embodiment, since the high-temperature heat source 5 to be cooled has a cylindrical heat dissipation surface as shown in Fig. 1, the evaporator has an annular shape with a circular hole having a dimension adapted to the cylindrical heat dissipation surface of the heat source. In addition, the surface of the hole of the evaporator 1 is brought into close contact with the cylindrical heat dissipation surface of heat source 5 in order to reduce thermal contact resistance. Condenser 3 is of a fin-tube type, and cools the working fluid flowing inside the pipe by flowing air around the same.
The pipe 4 of the condenser for flowing the working fluid may be any of a parallel flow type and a serpentine type. The condenser 3 is provided such that an inlet of a gas is located higher than an outlet of a condensed liquid. Gas pipe 2 extending from evaporator 1 to condenser 3 has a larger diameter than liquid pipe 4 extending from the condenser 3 to the evaporator 1. Therefore, gas pipe 2 has a flow resistance smaller than the liquid pipe 4, so as to prevent backflow of the working fluid and hard starting. The diameter of the liquid pipe is determined based on the designed heat load and thermal property of the working fluid. In order to form a thermosiphon, condenser 3 is located above evaporator 1.
In the present embodiment, pure water is contained as the working fluid.
Here, the contained amount is assumed to be the mass of the working fluid which fills 1/3 to 2/3 of the total of a possible volume of liquid pool in the condenser 3 (for example, a header pipe at an outlet of the condenser), the volume of the liquid pipe and the volume of the evaporator, and of which saturated vapor fills a remaining volume at an operating temperature. Such a contained amount allows smooth operation of the working fluid.
As to the operation, as shown in Fig. 1, the water evaporates by depriving high-temperature heat source of heat in evaporator 1. The vapor produced in evaporator 1 runs through gas pipe 2 utilizing a vapor pressure difference caused by the temperature difference between condenser 3 and evaporator I and flows in condenser 3, in which the vapor is deprived of heat by the air outside the pipe and condensed. The liquid condensed in condenser 3 returns to evaporator 1 through liquid pipe 4 by gravity. In this manner, the process circulation of the working fluid, heat absorption in the evaporator, and heat dissipation in the condenser is repeated.
One feature of the embodiment of the present invention resides in introduction of the liquid from the condenser through the upper portion of the evaporator 1 as shown in Fig. 1, instead of introduction through the lower portion thereof (see Fig. 5).
In the arrangement of the conventional loop-type thermosiphon shown in Figs. 4 and 5, a cold liquid is supplied to the lower portion of the evaporator 1.
Accordingly, the temperature gradient in the liquid pooled in the evaporator 1 does not considerably affect the flow, without promoting evaporation. If the evaporator 1 operates under a condition far from the designed heat load, particularly under such a condition as small heat load, bubbles adhered to a heat transfer surface takes longer time to form.
Then, the liquid is further pooled in the evaporator I and the bubbles are less likely to escape. As described above, in the conventional thermosiphon, significant temperature fluctuation results in the heat source due to variation of circulation flow rate of the working fluid or suspension of circulation (see Fig. 7).
In the loop-type thermosiphon according to the embodiment shown in Fig. 1, the liquid from the condenser 3 is introduced through the upper portion of the evaporator 1, so that the supercooled liquid initially falls on the heat absorption portion at a high temperature or on a internal fin (not shown), on which the liquid is preheated. The internal fin is attached to the heat absorption portion and formed inwardly, so that evaporation of the liquid pooled in the evaporator 1 is promoted. In addition, when a colder liquid is introduced from above the liquid level in the evaporator 1, the liquid tends to move downward by gravity due to a difference in density. Then, the liquid in the evaporator 1 is stirred and evaporation is promoted, whereby the bubbles present on the heat transfer surface tend to be separated and destroyed. In this manner, the loop-type thermosiphon according to the present embodiment can achieve a stable temperature of the heat source even under a condition far from the designed heat load.
Though the gas-liquid separation tank is not provided in the loop-type thermosiphon shown in Fig. 1, a gas-liquid separation tank 6 may be provided between the condenser and the evaporator as shown in Fig. 2. It is noted, however, that the inner volume of the gas-liquid separation tank should be regarded as a portion of the liquid pipe in determining the contained amount. Provision of the gas-liquid separation tank may be effective for attaining a stable operation of the loop-type thermosiphon.
Addition of ethanol to the water serving as the working fluid by not larger than 60% can lower a tolerable temperature of an environment during operation or transportation.
Figure 3 is a conceptual diagram of a Stirling refrigerator according to a second embodiment of the present invention, provided with the loop-type thermosiphon. The Stirling refrigerator in Fig. 3 is constituted of a Stirling cooler provided in a refrigerator main body 19, the loop-type thermosiphon attached in order to cool a high-temperature portion of the Stirling cooler, a low-temperature side heat exchange system transferring the cold of a low-temperature portion of the Stirling cooler to the inside of the refrigerator, the refrigerator main body, and the like.
Though the low-temperature side heat exchange system is implemented by the loop-type thermosiphon, it is the loop-type thermosiphon not of interest in the present embodiment.
A Stirling cooler 11 having cylindrical high-temperature and low-temperature portions is arranged on a back surface of the refrigerator 19. Evaporator 1 of the loop-type thermosiphon cooling a high-temperature portion 13 of the Stirling cooler is attached to and brought into close contact with the high-temperature portion of the Stirling cooler. In addition, the condenser 3 is placed on the refrigerator main body 19 and evaporator 1 and condenser 3 are connected to each other by a pipe as shown in Fig. 1, so that the loop-type thermosiphon in the present embodiment is mounted on the Stirling refrigerator. Liquid pipe 4 is inserted in evaporator 1 through its upper portion. As a working fluid, pure water or a mixture of pure water and ethanol is contained.
The low-temperature side heat exchange system supplies the cold of a low-temperature portion 12 of the Stirling cooler to the inside of the refrigerator with a refrigerator cooling apparatus 15 utilizing a secondary refrigerant.
Refrigerator cooling apparatus 15 is provided by a cold-air duct in the refrigerator.
When Stirling cooler 11 operates, the temperature of high-temperature portion 13 of the Stirling cooler is raised. Then, the working fluid is heated and evaporates in evaporator 1 and flows in condenser 3 through gas pipe 2. At the same time, outside air is introduced by the rotation of a fan 7, so that the gas of the working fluid from evaporator 1 is cooled and condensed in condenser 3. The working fluid liquefied in condenser 3 returns to evaporator 1 by gravity through liquid pipe 4 and an introduction pipe 4a. When the liquefied working fluid returns to evaporator 1, the working fluid comes in contact with a heat absorption portion 1 a and/or the internal fin (not shown) of the evaporator 1 so as to exchange heat. In this manner, natural circulation of the working fluid is attained and the heat of Stirling cooler 11 is transferred to the outside air.
The operation of Stirling cooler 11 serves to lower the temperature of low-temperature portion 12, and the secondary refrigerant in the heat exchange system flowing through the low-temperature portion is deprived of heat. On the other hand, the secondary refrigerant in the low-temperature side heat exchange system absorbs heat from the air inside the refrigerator in the refrigerator cooling apparatus by rotation of a cooling fan 16 on which a damper 17 is arranged. In the present embodiment, the secondary refrigerant in the low-temperature side heat exchange system attains natural circulation by gravity. Alternatively, circulation may naturally be attained by circulation means using a pump. As described above, the cold of Stirling cooler 11 is continuously provided to the air inside the refrigerator.
In addition, drain water resulting from defrosting of refrigerator cooling apparatus 15 is discharged from a drain water outlet 18.
Figure 4 shows temperature fluctuation of the high-temperature heat source when a loop-type thermosiphon according to a third embodiment of the present invention is employed. The loop-type thermosiphon in the present embodiment is obtained merely by varying the manner of return of the liquid to the evaporator in the conventional loop-type thermosiphon shown in Fig. 6. In other words, the loop-type thermosiphon is structured such that the condensed working fluid is returned so as to contact the heat absorption portion which is not in contact with the liquid pool, instead of being directly introduced into the liquid pool.
The variation with time of the temperature of the high-temperature heat source shown in Fig. 4 exhibits the effect obtained under the condition of when the heat load is the same as in the conventional loop-type thermosiphon. As compared with the large temperature fluctuation of the heat source in the conventional loop-type thermosiphon shown in Fig. 7, stable temperature transition can be achieved.
The loop-type thermosiphon shown in Fig. 1 is constituted of an evaporator 1, a condenser 3, a gas pipe 2 extending from evaporator 1 to condenser 3, and a liquid pipe 4 extending from condenser 3 to evaporator 1. In the present embodiment, since the high-temperature heat source 5 to be cooled has a cylindrical heat dissipation surface as shown in Fig. 1, the evaporator has an annular shape with a circular hole having a dimension adapted to the cylindrical heat dissipation surface of the heat source. In addition, the surface of the hole of the evaporator 1 is brought into close contact with the cylindrical heat dissipation surface of heat source 5 in order to reduce thermal contact resistance. Condenser 3 is of a fin-tube type, and cools the working fluid flowing inside the pipe by flowing air around the same.
The pipe 4 of the condenser for flowing the working fluid may be any of a parallel flow type and a serpentine type. The condenser 3 is provided such that an inlet of a gas is located higher than an outlet of a condensed liquid. Gas pipe 2 extending from evaporator 1 to condenser 3 has a larger diameter than liquid pipe 4 extending from the condenser 3 to the evaporator 1. Therefore, gas pipe 2 has a flow resistance smaller than the liquid pipe 4, so as to prevent backflow of the working fluid and hard starting. The diameter of the liquid pipe is determined based on the designed heat load and thermal property of the working fluid. In order to form a thermosiphon, condenser 3 is located above evaporator 1.
In the present embodiment, pure water is contained as the working fluid.
Here, the contained amount is assumed to be the mass of the working fluid which fills 1/3 to 2/3 of the total of a possible volume of liquid pool in the condenser 3 (for example, a header pipe at an outlet of the condenser), the volume of the liquid pipe and the volume of the evaporator, and of which saturated vapor fills a remaining volume at an operating temperature. Such a contained amount allows smooth operation of the working fluid.
As to the operation, as shown in Fig. 1, the water evaporates by depriving high-temperature heat source of heat in evaporator 1. The vapor produced in evaporator 1 runs through gas pipe 2 utilizing a vapor pressure difference caused by the temperature difference between condenser 3 and evaporator I and flows in condenser 3, in which the vapor is deprived of heat by the air outside the pipe and condensed. The liquid condensed in condenser 3 returns to evaporator 1 through liquid pipe 4 by gravity. In this manner, the process circulation of the working fluid, heat absorption in the evaporator, and heat dissipation in the condenser is repeated.
One feature of the embodiment of the present invention resides in introduction of the liquid from the condenser through the upper portion of the evaporator 1 as shown in Fig. 1, instead of introduction through the lower portion thereof (see Fig. 5).
In the arrangement of the conventional loop-type thermosiphon shown in Figs. 4 and 5, a cold liquid is supplied to the lower portion of the evaporator 1.
Accordingly, the temperature gradient in the liquid pooled in the evaporator 1 does not considerably affect the flow, without promoting evaporation. If the evaporator 1 operates under a condition far from the designed heat load, particularly under such a condition as small heat load, bubbles adhered to a heat transfer surface takes longer time to form.
Then, the liquid is further pooled in the evaporator I and the bubbles are less likely to escape. As described above, in the conventional thermosiphon, significant temperature fluctuation results in the heat source due to variation of circulation flow rate of the working fluid or suspension of circulation (see Fig. 7).
In the loop-type thermosiphon according to the embodiment shown in Fig. 1, the liquid from the condenser 3 is introduced through the upper portion of the evaporator 1, so that the supercooled liquid initially falls on the heat absorption portion at a high temperature or on a internal fin (not shown), on which the liquid is preheated. The internal fin is attached to the heat absorption portion and formed inwardly, so that evaporation of the liquid pooled in the evaporator 1 is promoted. In addition, when a colder liquid is introduced from above the liquid level in the evaporator 1, the liquid tends to move downward by gravity due to a difference in density. Then, the liquid in the evaporator 1 is stirred and evaporation is promoted, whereby the bubbles present on the heat transfer surface tend to be separated and destroyed. In this manner, the loop-type thermosiphon according to the present embodiment can achieve a stable temperature of the heat source even under a condition far from the designed heat load.
Though the gas-liquid separation tank is not provided in the loop-type thermosiphon shown in Fig. 1, a gas-liquid separation tank 6 may be provided between the condenser and the evaporator as shown in Fig. 2. It is noted, however, that the inner volume of the gas-liquid separation tank should be regarded as a portion of the liquid pipe in determining the contained amount. Provision of the gas-liquid separation tank may be effective for attaining a stable operation of the loop-type thermosiphon.
Addition of ethanol to the water serving as the working fluid by not larger than 60% can lower a tolerable temperature of an environment during operation or transportation.
Figure 3 is a conceptual diagram of a Stirling refrigerator according to a second embodiment of the present invention, provided with the loop-type thermosiphon. The Stirling refrigerator in Fig. 3 is constituted of a Stirling cooler provided in a refrigerator main body 19, the loop-type thermosiphon attached in order to cool a high-temperature portion of the Stirling cooler, a low-temperature side heat exchange system transferring the cold of a low-temperature portion of the Stirling cooler to the inside of the refrigerator, the refrigerator main body, and the like.
Though the low-temperature side heat exchange system is implemented by the loop-type thermosiphon, it is the loop-type thermosiphon not of interest in the present embodiment.
A Stirling cooler 11 having cylindrical high-temperature and low-temperature portions is arranged on a back surface of the refrigerator 19. Evaporator 1 of the loop-type thermosiphon cooling a high-temperature portion 13 of the Stirling cooler is attached to and brought into close contact with the high-temperature portion of the Stirling cooler. In addition, the condenser 3 is placed on the refrigerator main body 19 and evaporator 1 and condenser 3 are connected to each other by a pipe as shown in Fig. 1, so that the loop-type thermosiphon in the present embodiment is mounted on the Stirling refrigerator. Liquid pipe 4 is inserted in evaporator 1 through its upper portion. As a working fluid, pure water or a mixture of pure water and ethanol is contained.
The low-temperature side heat exchange system supplies the cold of a low-temperature portion 12 of the Stirling cooler to the inside of the refrigerator with a refrigerator cooling apparatus 15 utilizing a secondary refrigerant.
Refrigerator cooling apparatus 15 is provided by a cold-air duct in the refrigerator.
When Stirling cooler 11 operates, the temperature of high-temperature portion 13 of the Stirling cooler is raised. Then, the working fluid is heated and evaporates in evaporator 1 and flows in condenser 3 through gas pipe 2. At the same time, outside air is introduced by the rotation of a fan 7, so that the gas of the working fluid from evaporator 1 is cooled and condensed in condenser 3. The working fluid liquefied in condenser 3 returns to evaporator 1 by gravity through liquid pipe 4 and an introduction pipe 4a. When the liquefied working fluid returns to evaporator 1, the working fluid comes in contact with a heat absorption portion 1 a and/or the internal fin (not shown) of the evaporator 1 so as to exchange heat. In this manner, natural circulation of the working fluid is attained and the heat of Stirling cooler 11 is transferred to the outside air.
The operation of Stirling cooler 11 serves to lower the temperature of low-temperature portion 12, and the secondary refrigerant in the heat exchange system flowing through the low-temperature portion is deprived of heat. On the other hand, the secondary refrigerant in the low-temperature side heat exchange system absorbs heat from the air inside the refrigerator in the refrigerator cooling apparatus by rotation of a cooling fan 16 on which a damper 17 is arranged. In the present embodiment, the secondary refrigerant in the low-temperature side heat exchange system attains natural circulation by gravity. Alternatively, circulation may naturally be attained by circulation means using a pump. As described above, the cold of Stirling cooler 11 is continuously provided to the air inside the refrigerator.
In addition, drain water resulting from defrosting of refrigerator cooling apparatus 15 is discharged from a drain water outlet 18.
Figure 4 shows temperature fluctuation of the high-temperature heat source when a loop-type thermosiphon according to a third embodiment of the present invention is employed. The loop-type thermosiphon in the present embodiment is obtained merely by varying the manner of return of the liquid to the evaporator in the conventional loop-type thermosiphon shown in Fig. 6. In other words, the loop-type thermosiphon is structured such that the condensed working fluid is returned so as to contact the heat absorption portion which is not in contact with the liquid pool, instead of being directly introduced into the liquid pool.
The variation with time of the temperature of the high-temperature heat source shown in Fig. 4 exhibits the effect obtained under the condition of when the heat load is the same as in the conventional loop-type thermosiphon. As compared with the large temperature fluctuation of the heat source in the conventional loop-type thermosiphon shown in Fig. 7, stable temperature transition can be achieved.
Examples, including those mentioned in the first to third embodiments of the present invention, will comprehensively be explained, referring to the effects of the loop-type thermosiphon and the refrigerator in each embodiment of the present invention.
In one embodiment of the present invention, a loop-type thermosiphon transferring heat from a high-temperature heat source having a heat dissipation surface includes an evaporator depriving the high-temperature heat source of heat, a condenser arranged above the high-temperature heat source, and a pipe connecting the evaporator and the condenser so as to form a loop. The loop-type thermosiphon contains a working fluid, and drops the liquid of the working fluid from the condenser on a heat absorption portion when it is introduced into the evaporator, in order to exchange heat. Therefore, a loop-type thermosiphon is capable of maintaining a stable temperature for the high-temperature heat source can be provided.
In addition, in one embodiment according to the present invention different from that described above, an internal fin is provided in the heat absorption portion in the evaporator constituting the loop-type thermosiphon. The liquid of the working fluid condensed in the condenser is introduced into the evaporator through the upper portion thereof, in order that the liquid of the working fluid falls on the heat absorption portion or the internal fin in the evaporator. Here, the evaporator may have a box-shape, or may have an annular shape by combining semi-annular portions.
Alternatively, combination of portions of another shape may be employed. The heat absorption portion may be of a cylindrical shape or formed like a hole so as to receive the high-temperature heat source. According to the structure described above, the heat dissipation amount from an upper half of a cylindrical heat dissipation surface of the high-temperature heat source is not as large as that in a lower half thereof.
Therefore, the liquid of the working fluid can be preheated and a uniform and stable temperature of the high-temperature heat source in the evaporator can be achieved.
In an arrangement of a loop-type thermosiphon according to another embodiment of the present invention, flow resistance of the gas pipe guiding vapor produced in the evaporator to the condenser is made smaller than that of the liquid pipe guiding the liquid condensed in the condenser to the evaporator.
According to such an arrangement, backflow of the working fluid and hard starting in the thermosiphon can be prevented.
In one embodiment of the present invention, a loop-type thermosiphon transferring heat from a high-temperature heat source having a heat dissipation surface includes an evaporator depriving the high-temperature heat source of heat, a condenser arranged above the high-temperature heat source, and a pipe connecting the evaporator and the condenser so as to form a loop. The loop-type thermosiphon contains a working fluid, and drops the liquid of the working fluid from the condenser on a heat absorption portion when it is introduced into the evaporator, in order to exchange heat. Therefore, a loop-type thermosiphon is capable of maintaining a stable temperature for the high-temperature heat source can be provided.
In addition, in one embodiment according to the present invention different from that described above, an internal fin is provided in the heat absorption portion in the evaporator constituting the loop-type thermosiphon. The liquid of the working fluid condensed in the condenser is introduced into the evaporator through the upper portion thereof, in order that the liquid of the working fluid falls on the heat absorption portion or the internal fin in the evaporator. Here, the evaporator may have a box-shape, or may have an annular shape by combining semi-annular portions.
Alternatively, combination of portions of another shape may be employed. The heat absorption portion may be of a cylindrical shape or formed like a hole so as to receive the high-temperature heat source. According to the structure described above, the heat dissipation amount from an upper half of a cylindrical heat dissipation surface of the high-temperature heat source is not as large as that in a lower half thereof.
Therefore, the liquid of the working fluid can be preheated and a uniform and stable temperature of the high-temperature heat source in the evaporator can be achieved.
In an arrangement of a loop-type thermosiphon according to another embodiment of the present invention, flow resistance of the gas pipe guiding vapor produced in the evaporator to the condenser is made smaller than that of the liquid pipe guiding the liquid condensed in the condenser to the evaporator.
According to such an arrangement, backflow of the working fluid and hard starting in the thermosiphon can be prevented.
Moreover, in another embodiment of the present invention which is dependent on the amount of heat transferred from the high-temperature heat source, the flow resistance of the pipe is made smaller if the amount of transferred heat is large, and it is made larger if the amount of transferred heat is small. If the diameter of the pipe is determined based on such an arrangement, more stable circulation flow rate of the working fluid can be achieved. Here, a reference value of magnitude corresponding to the amount of transferred heat, for example, may be set to 75% of the designed load. That is, if the amount of heat generation from the heat source is not larger than 75% of the designed load, the flow resistance of the pipe is made larger, and if it exceeds 75%, the flow resistance of the pipe is made smaller. Alternatively, another reference value such as 50% of the designed load may be implemented.
In a loop-type thermosiphon according to another embodiment of the present invention, the contained amount of the working fluid can be set to the mass of the working fluid of which fills 1/3 to 2/3 of the total, possible volume of liquid pool in the condenser at an operating temperature, the volume of the liquid pipe (the pipe) and the volume of the evaporator, and of which saturated vapor fills a remaining volume at the operating temperature. Accordingly, a disadvantage resulting from a contained amount of the working fluid can be eliminated.
A loop-type thermosiphon according to yet another embodiment of the present invention employs a natural refrigerant such as carbonic acid gas, water, hydrocarbon, or the like as the working fluid, and can provide an environmentally-friendly heat exchange process. Particularly when water is employed as the working fluid, a safe loop-type thermosiphon free from toxic or flammable properties can be obtained. Addition of ethanol by not larger than 60% can expand a range of temperature in an environment in which the loop-type thermosiphon employing water as the working fluid can operate.
In a refrigerator equipped with a Stirling cooler employing the loop-type thermosiphon according to any one of the embodiments of the present invention described above, the evaporator of the loop-type thermosiphon described above exchanges heat with the high-temperature portion of the Stirling cooler.
Specifically, both of these components are brought into close contact with each other. In addition, the condenser can be arranged in a position higher than that of the high-temperature portion of the Stirling cooler of the refrigerator. According to such an arrangement, even when the heat load of the Stirling refrigerator is varied, the Stirling cooler can achieve stable operation. In addition, as the working fluid achieves natural circulation by gravity, it is not necessary to provide a pump. Therefore, high reliability and efficiency can be effectively achieved.
The effects in each embodiment of the present invention have been enumerated and explained. In the present invention, however, a loop-type thermosiphon according to an embodiment covering a broadest scope does not have to attain all effects in each embodiment described above. The loop-type thermosiphon in the embodiment covering the broadest scope should only achieve a stable operation adapted to fluctuation of load of the heat source.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Industrial Applicability The loop-type thermosiphon according to the present invention can absorb fluctuation of heat load of the heat source and attain a stable operation.
Therefore, the loop-type thermosiphon described above is used for cooling the high-temperature portion of the Stirling cooler in the refrigerator employing as a cooling apparatus the Stirling cooler, without using CFC and free from greenhouse gas emission. The loop-type thermosiphon is expected to contribute to ensuring stable freezing performance throughout a year.
In a loop-type thermosiphon according to another embodiment of the present invention, the contained amount of the working fluid can be set to the mass of the working fluid of which fills 1/3 to 2/3 of the total, possible volume of liquid pool in the condenser at an operating temperature, the volume of the liquid pipe (the pipe) and the volume of the evaporator, and of which saturated vapor fills a remaining volume at the operating temperature. Accordingly, a disadvantage resulting from a contained amount of the working fluid can be eliminated.
A loop-type thermosiphon according to yet another embodiment of the present invention employs a natural refrigerant such as carbonic acid gas, water, hydrocarbon, or the like as the working fluid, and can provide an environmentally-friendly heat exchange process. Particularly when water is employed as the working fluid, a safe loop-type thermosiphon free from toxic or flammable properties can be obtained. Addition of ethanol by not larger than 60% can expand a range of temperature in an environment in which the loop-type thermosiphon employing water as the working fluid can operate.
In a refrigerator equipped with a Stirling cooler employing the loop-type thermosiphon according to any one of the embodiments of the present invention described above, the evaporator of the loop-type thermosiphon described above exchanges heat with the high-temperature portion of the Stirling cooler.
Specifically, both of these components are brought into close contact with each other. In addition, the condenser can be arranged in a position higher than that of the high-temperature portion of the Stirling cooler of the refrigerator. According to such an arrangement, even when the heat load of the Stirling refrigerator is varied, the Stirling cooler can achieve stable operation. In addition, as the working fluid achieves natural circulation by gravity, it is not necessary to provide a pump. Therefore, high reliability and efficiency can be effectively achieved.
The effects in each embodiment of the present invention have been enumerated and explained. In the present invention, however, a loop-type thermosiphon according to an embodiment covering a broadest scope does not have to attain all effects in each embodiment described above. The loop-type thermosiphon in the embodiment covering the broadest scope should only achieve a stable operation adapted to fluctuation of load of the heat source.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Industrial Applicability The loop-type thermosiphon according to the present invention can absorb fluctuation of heat load of the heat source and attain a stable operation.
Therefore, the loop-type thermosiphon described above is used for cooling the high-temperature portion of the Stirling cooler in the refrigerator employing as a cooling apparatus the Stirling cooler, without using CFC and free from greenhouse gas emission. The loop-type thermosiphon is expected to contribute to ensuring stable freezing performance throughout a year.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A loop-type thermosiphon for transferring heat from a cylindrical high-temperature heat source having a central axis extending in a horizontal direction using a working fluid, comprising:
an annular evaporator having a cylindrical heat absorption portion attached to an outer surface of said high-temperature heat source and for evaporating said working fluid by depriving said high-temperature heat source of heat through the heat absorption portion;
a condenser located above said high-temperature heat source and for condensing the working fluid that has evaporated in said evaporator; and a gas pipe and a liquid pipe connecting said evaporator and said condenser so as to form a loop; wherein an outlet of said liquid pipe is positioned near a top of said heat absorption portion such that said working fluid, that has passed through said condenser and has been condensed, is made to fall on the top of said heat absorption portion.
an annular evaporator having a cylindrical heat absorption portion attached to an outer surface of said high-temperature heat source and for evaporating said working fluid by depriving said high-temperature heat source of heat through the heat absorption portion;
a condenser located above said high-temperature heat source and for condensing the working fluid that has evaporated in said evaporator; and a gas pipe and a liquid pipe connecting said evaporator and said condenser so as to form a loop; wherein an outlet of said liquid pipe is positioned near a top of said heat absorption portion such that said working fluid, that has passed through said condenser and has been condensed, is made to fall on the top of said heat absorption portion.
2. The loop-type thermosiphon according to claim 1, wherein said annular evaporator has an internal fin provided at a heat absorption surface.
3. The loop-type thermosiphon according to claim 1 or 2, wherein a contained amount of the working fluid refers to such a contained amount that 1/3 to 2/3 of a total volume of a possible volume of liquid pool in said condenser at an operation temperature, a volume of the pipe and a volume of the evaporator is filled with a liquid of said working fluid and a remaining volume of said total volume is filled with saturated vapor of said working fluid.
4. A Stirling refrigerator having a Stirling cooler, said Stirling cooler including a loop-type thermosiphon according to any one of claims 1 to 3, wherein said evaporator exchanges heat with a high-temperature portion of said Stirling cooler, and said condenser is located above said high-temperature portion.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002-104896 | 2002-04-08 | ||
| JP2002104896A JP4033699B2 (en) | 2002-04-08 | 2002-04-08 | Loop thermosyphon and Stirling refrigerator |
| PCT/JP2003/004399 WO2003085345A1 (en) | 2002-04-08 | 2003-04-07 | Loop-type thermosiphon and stirling refrigerator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2481477A1 CA2481477A1 (en) | 2003-10-16 |
| CA2481477C true CA2481477C (en) | 2011-12-20 |
Family
ID=28786352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2481477A Expired - Fee Related CA2481477C (en) | 2002-04-08 | 2003-04-07 | Loop-type thermosiphon and stirling refrigerator |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20050172644A1 (en) |
| EP (1) | EP1493983A4 (en) |
| JP (1) | JP4033699B2 (en) |
| KR (1) | KR100691578B1 (en) |
| CN (1) | CN100350211C (en) |
| AU (1) | AU2003236294A1 (en) |
| BR (1) | BR0309143A (en) |
| CA (1) | CA2481477C (en) |
| WO (1) | WO2003085345A1 (en) |
Families Citing this family (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3746496B2 (en) * | 2003-06-23 | 2006-02-15 | シャープ株式会社 | refrigerator |
| WO2005008160A1 (en) | 2003-07-23 | 2005-01-27 | Sharp Kabushiki Kaisha | Loop type thermo syphone, heat radiation system, heat exchange system, and stirling cooling chamber |
| US20070028626A1 (en) * | 2003-09-02 | 2007-02-08 | Sharp Kabushiki Kaisha | Loop type thermo siphon, stirling cooling chamber, and cooling apparatus |
| JP2006084111A (en) * | 2004-09-16 | 2006-03-30 | Sharp Corp | Refrigerator |
| US9074825B2 (en) | 2007-09-28 | 2015-07-07 | Panasonic Intellectual Property Management Co., Ltd. | Heatsink apparatus and electronic device having the same |
| KR100909929B1 (en) * | 2007-10-04 | 2009-07-29 | 순 동 강 | Heat exchanger using natural air-cooled heat pipe |
| FR2922003A1 (en) * | 2007-10-09 | 2009-04-10 | Christian Michel Gillet | Household freezing cabinet/cell for preserving food in building, has climatic cold capturing and storage system exploiting natural thermosiphon fluid circulation phenomenon, and sphere blocking fluid by its expansion under freezing effect |
| US8262263B2 (en) * | 2007-11-16 | 2012-09-11 | Khanh Dinh | High reliability cooling system for LED lamps using dual mode heat transfer loops |
| KR20160027208A (en) | 2010-05-27 | 2016-03-09 | 존슨 컨트롤스 테크놀러지 컴퍼니 | Thermosyphon coolers for cooling systems with cooling towers |
| KR101219359B1 (en) * | 2010-11-26 | 2013-01-21 | 강희주 | heat transfer device |
| US9897365B2 (en) | 2011-12-14 | 2018-02-20 | Lg Electronics Inc. | Refrigerator, thermosyphon, and solenoid valve and method for controlling the same |
| US20130291555A1 (en) | 2012-05-07 | 2013-11-07 | Phononic Devices, Inc. | Thermoelectric refrigeration system control scheme for high efficiency performance |
| WO2013169774A2 (en) | 2012-05-07 | 2013-11-14 | Phononic Devices, Inc. | Thermoelectric heat exchanger component including protective heat spreading lid and optimal thermal interface resistance |
| FR3002028B1 (en) * | 2013-02-14 | 2017-06-02 | Euro Heat Pipes | DEVICE FOR TRANSPORTING HEAT WITH DIPHASIC FLUID |
| DE102014109293B4 (en) * | 2013-07-03 | 2020-02-20 | Thorsten Rapp | Device for heating a degreasing and / or cleaning system |
| US10458683B2 (en) | 2014-07-21 | 2019-10-29 | Phononic, Inc. | Systems and methods for mitigating heat rejection limitations of a thermoelectric module |
| US9593871B2 (en) | 2014-07-21 | 2017-03-14 | Phononic Devices, Inc. | Systems and methods for operating a thermoelectric module to increase efficiency |
| EP3209957B1 (en) * | 2014-10-21 | 2021-04-07 | LG Electronics Inc. | Defrosting device and refrigerator having the same |
| KR101645428B1 (en) * | 2015-04-17 | 2016-08-16 | 한국원자력연구원 | Spray heat exchanger on the saturated steam |
| US20180330933A1 (en) * | 2017-03-29 | 2018-11-15 | Brian Chan | Cooling devices and instruments including them |
| JP6902102B2 (en) * | 2017-07-05 | 2021-07-14 | Ｐｈｃホールディングス株式会社 | Refrigerator |
| US10677369B2 (en) | 2017-08-03 | 2020-06-09 | Fluke Corporation | Temperature calibration system comprising a valve in a closed fluidic system |
| US10591366B2 (en) | 2017-08-03 | 2020-03-17 | Fluke Corporation | Temperature calibration system with separable cooling assembly |
| CN107560227B (en) * | 2017-10-09 | 2019-12-17 | 中国科学院理化技术研究所 | Thermally-driven Stirling heat pump |
| KR102140944B1 (en) * | 2018-06-27 | 2020-08-05 | 한국전력공사 | Energy Storage System with Air conditioner using thermosiphon |
| US11008927B2 (en) | 2019-04-10 | 2021-05-18 | James Moore | Alternative method of heat removal from an internal combustion engine |
| CN112667036A (en) * | 2019-10-16 | 2021-04-16 | 北京百度网讯科技有限公司 | Computer server |
| US11744044B2 (en) | 2020-11-05 | 2023-08-29 | Deeia, Inc. | Loop thermosyphon devices and systems, and related methods |
| KR102393685B1 (en) * | 2021-08-18 | 2022-05-03 | 주식회사 코벡엔지니어링 | High-efficiency heat exchanging system for recycling waste cold/hot heat |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2083611A (en) * | 1931-12-05 | 1937-06-15 | Carrier Corp | Cooling system |
| FR1468770A (en) * | 1965-08-24 | 1967-02-10 | Thomson Houston Comp Francaise | Improvements to liquid supply circuits for vaporized cooled electron tubes |
| US3371298A (en) * | 1966-02-03 | 1968-02-27 | Westinghouse Electric Corp | Cooling system for electrical apparatus |
| US3576903A (en) * | 1968-04-29 | 1971-04-27 | Minnesota Mining & Mfg | Epoxy-terminated adducts of carboxy terminated polyesters and polyepoxides |
| US3756903A (en) * | 1971-06-15 | 1973-09-04 | Wakefield Eng Inc | Closed loop system for maintaining constant temperature |
| US3986550A (en) * | 1973-10-11 | 1976-10-19 | Mitsubishi Denki Kabushiki Kaisha | Heat transferring apparatus |
| US4117525A (en) * | 1977-09-09 | 1978-09-26 | Electric Power Research Institute, Inc. | Overpressure protection for vaporization cooled electrical apparatus |
| US4321421A (en) * | 1979-03-07 | 1982-03-23 | General Electric Company | Vaporization cooled transformer having a high voltage |
| US4280333A (en) * | 1979-03-16 | 1981-07-28 | The United States Of America As Represented By The United States Department Of Energy | Passive environmental temperature control system |
| JP2550770B2 (en) * | 1990-10-11 | 1996-11-06 | 日本電気株式会社 | Electronic component cooling mechanism |
| US5159972A (en) * | 1991-03-21 | 1992-11-03 | Florida Power Corporation | Controllable heat pipes for thermal energy transfer |
| JP2599516Y2 (en) * | 1993-11-08 | 1999-09-13 | 株式会社フジクラ | Geothermal heat source heat pipe snow melting device |
| US5642622A (en) * | 1995-08-17 | 1997-07-01 | Sunpower, Inc. | Refrigerator with interior mounted heat pump |
| GB2317222B (en) * | 1996-09-04 | 1998-11-25 | Babcock & Wilcox Co | Heat pipe heat exchangers for subsea pipelines |
| KR100276076B1 (en) * | 1997-12-17 | 2001-03-02 | 이계철 | Device for controlling instability of flow in loop-type thermosyphon/heat pipe |
| US6761212B2 (en) * | 2000-05-25 | 2004-07-13 | Liebert Corporation | Spiral copper tube and aluminum fin thermosyphon heat exchanger |
| JP2002013885A (en) * | 2000-06-28 | 2002-01-18 | Twinbird Corp | Thermo-siphon for refrigerator |
| JP3625182B2 (en) * | 2000-08-22 | 2005-03-02 | シャープ株式会社 | Stirling refrigerator and Stirling refrigerator |
| CN1232791C (en) * | 2000-08-22 | 2005-12-21 | 夏普公司 | Stirling refrigerator |
-
2002
- 2002-04-08 JP JP2002104896A patent/JP4033699B2/en not_active Expired - Fee Related
-
2003
- 2003-04-07 CN CNB038077752A patent/CN100350211C/en not_active Expired - Fee Related
- 2003-04-07 BR BR0309143-0A patent/BR0309143A/en not_active IP Right Cessation
- 2003-04-07 WO PCT/JP2003/004399 patent/WO2003085345A1/en active Application Filing
- 2003-04-07 US US10/510,502 patent/US20050172644A1/en not_active Abandoned
- 2003-04-07 KR KR1020047015931A patent/KR100691578B1/en not_active IP Right Cessation
- 2003-04-07 AU AU2003236294A patent/AU2003236294A1/en not_active Abandoned
- 2003-04-07 CA CA2481477A patent/CA2481477C/en not_active Expired - Fee Related
- 2003-04-07 EP EP03745945A patent/EP1493983A4/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| KR20040094913A (en) | 2004-11-10 |
| JP4033699B2 (en) | 2008-01-16 |
| EP1493983A1 (en) | 2005-01-05 |
| CN100350211C (en) | 2007-11-21 |
| WO2003085345A1 (en) | 2003-10-16 |
| EP1493983A4 (en) | 2006-06-07 |
| CN1646871A (en) | 2005-07-27 |
| CA2481477A1 (en) | 2003-10-16 |
| US20050172644A1 (en) | 2005-08-11 |
| BR0309143A (en) | 2005-01-11 |
| KR100691578B1 (en) | 2007-03-12 |
| AU2003236294A1 (en) | 2003-10-20 |
| JP2003302178A (en) | 2003-10-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2481477C (en) | Loop-type thermosiphon and stirling refrigerator | |
| US5940270A (en) | Two-phase constant-pressure closed-loop water cooling system for a heat producing device | |
| JP4524289B2 (en) | Cooling system with bubble pump | |
| US8408022B2 (en) | Hybrid cascade vapor compression refrigeration system | |
| RU2005126722A (en) | HYBRID TYPE COOLING UNIT | |
| US8746007B2 (en) | Heat converter for condensation and refrigeration system using the same | |
| US20060185825A1 (en) | Loop type thermo syphone, heat radiation system, heat exchange system, and stirling cooling chamber | |
| US20100018224A1 (en) | Stirling cooler | |
| JP2008096085A (en) | Cooling apparatus | |
| JP4945712B2 (en) | Thermosiphon | |
| JP3906830B2 (en) | Natural circulation cooling device and heat exchange method using natural circulation cooling device | |
| TW514716B (en) | Stirling cooling apparatus, cooler, and refrigerator | |
| US20050016184A1 (en) | Stirling cooling device, cooling chamber, and refrigerator | |
| KR101116138B1 (en) | Cooling system using separated heatpipes | |
| JP2003302117A (en) | Heat radiation system for stirling engine and cooling chamber having the same | |
| JP2007078275A (en) | Heat exchanger for stirling refrigerating machine | |
| KR100609169B1 (en) | Cascade refrigerating cycle | |
| JPH08327181A (en) | Heat exchanger and freezer with heat exchanger | |
| KR200375016Y1 (en) | Vaporizing apparatus of heat pump type air conditioning equipment | |
| JP2003207253A (en) | Refrigerator | |
| JP4001607B2 (en) | Stirling refrigerator | |
| KR200282298Y1 (en) | Heating-exchange type refrigerating device | |
| JP2008057974A (en) | Cooling apparatus | |
| JPH06307725A (en) | Air conditioner | |
| KR20030080535A (en) | Heating-exchange type refrigerating device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20150407 |