EP3742070B1

EP3742070B1 - Cyclone heat recovery unit and heat pump system provided with said cyclone heat recovery unit

Info

Publication number: EP3742070B1
Application number: EP19741070.7A
Authority: EP
Inventors: Hiroshi Yamaguchi; Haruhiko Yamasaki; Petter Neksaa; Kazuhiro Hattori; Takeshi Kamimura
Original assignee: Mayekawa Manufacturing Co; Doshisha Co Ltd
Current assignee: Mayekawa Manufacturing Co; Doshisha Co Ltd
Priority date: 2018-01-19
Filing date: 2019-01-18
Publication date: 2023-07-19
Anticipated expiration: 2039-01-18
Also published as: EP3742070A4; EP3742070A1; JP2019124432A; WO2019142919A1; JP6945202B2

Description

TECHNICAL FIELD

The present invention relates to a cyclone heat recovery unit and a cascade heat pump system provided with a cyclone refrigeration device or cyclone heat recovery unit.

BACKGROUND ART

There are some refrigeration devices that uses carbon dioxide (CO₂) as refrigerant in the prior art.
This kind of refrigeration device comprises, for example, a compressor compressing CO₂ to saturation pressure or supercritical pressure at room temperature level, a condenser cooling and condensing the high pressure gas-phase CO₂ from the compressor, a CO₂ expansion device decompressing the condensed CO₂ to a pressure and temperature level below the triple point of CO₂ so as to transfer the condensed CO₂ into solid-gas two-phase CO₂ which is mixture of solid-phase CO₂ (dry ice) and gas-phase CO₂ (carbon dioxide gas), and a CO₂ sublimation means supplying heat due to sublimation of the solid-gas two-phase CO₂ to fluid to be cooled discharged from a cooling load and supplying the sublimated gas phase CO₂ to the compressor (see, for example, Patent Document 1).
The CO₂ sublimation means is a direct contact CO₂ sublimation device (see, Fig. 1 of Patent Document 1) or an indirect contact CO₂ sublimation device (see, Fig. 2 of Patent Document 1).
In the direct contact CO₂ sublimation device, the solid-gas two-phase CO₂ is ejected into the brine stored in a reservoir, and the solid-gas two-phase CO₂ is sublimated by heat of the brine, and the brine is cooled by this sublimation, and the cooled brine exchanges heat with the fluid to be cooled which is discharged from the cooling load.
In the indirect contact CO₂ sublimation device, the fluid to be cooled which is discharged from the cooling load flows into many cooling tubes arranged in parallel while the solid-gas two-phase CO₂ supplied from the CO₂ expansion device flows into a CO₂ passage provided between the cooling tubes, so that the solid-gas two-phase CO₂ is sublimated by heat of the fluid to be cooled in the cooling tubes and the fluid to be cooled is cooled to very low temperature by this sublimation.
However, according to this conventional refrigeration device, when the direct contact CO₂ sublimation device is used, solid-phase CO₂ deposits in the reservoir and accordingly a conduit draining the cooled fluid to be cooled from the reservoir is blocked, or the solid-phase CO₂ adheres to an exhaust nozzle for ejection of the solid-gas two-phase CO₂ into the reservoir and accordingly the exhaust nozzle is blocked, which sometimes hinders the operation of the refrigeration device. Also, when the indirect contact CO₂ sublimation device is used, the solid-phase CO₂ adheres to and deposits in the CO₂ passage and the CO₂ passage is blocked, which sometimes hinders the operation of the refrigeration device.
In addition, this refrigeration device uses the latent heat of the solid-phase CO₂ in the solid-gas two-phase state, but this refrigeration device has a drawback that the cooling capacity thereof is inferior to the case where the heat of sublimation of only the solid-phase CO₂ is used.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

Patent Document 1: JP 2004-308972 A . The following documents are also acknowledged: US 4224801A1 (Tyree, JR. ), which describes a refrigeration apparatus and method of refrigerating material using stored cryogenic refrigeration, and EP 2656741 A2 (Messer ), which describes an apparatus and method for cooling products.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

It is, therefore, an object of the present invention to provide refrigeration device that has a high cooling capacity and can be smoothly and continuously operated.

MEANS FOR SOLVING THE PROBLEMS

In order to achieve this object, the present invention provides a cyclone heat recovery unit according to claim 1, comprising a cyclone refrigeration device comprising: a cylindrical portion vertically extending and closed at a top end thereof; an exhaust pipe whose radius is smaller than the radius of the cylindrical portion connected coaxially to the top end of the cylindrical portion in fluid connection with an interior space of the cylindrical portion and extended upward from the top end of the cylindrical portion; a cooling portion connected to a bottom end of the cylindrical portion and provided with a cavity which communicates with the interior space of the cylindrical portion, the cylindrical portion having a refrigerant inlet at an upper portion of a side wall thereof; a refrigerant inflow pipe connected to the refrigerant inlet at one end thereof and receiving a supply of liquid-phase refrigerant compressed under high pressure at the other end thereof; and a first decompression unit provided in the refrigerant inflow pipe, wherein the liquid-phase refrigerant supplied to the refrigerant inflow pipe is decompressed to form solid-gas two-phase refrigerant by the first decompression unit, and the solid-gas two-phase refrigerant flows downward into the interior space of the cylindrical portion while forming a first vortex flow and separating into solid-phase refrigerant and gas-phase refrigerant, and the solid-phase refrigerant deposits in the cavity on the one hand and the gas-phase refrigerant forms a second vortex flow rising from the bottom of the cavity through an inside space of the first vortex flow to flow out of the exhaust pipe on the other hand, wherein the cyclone refrigeration device further comprises a circulation pipeline for fluid to be cooled extending through the cavity of the cooling portion, both ends of the circulation pipeline being connected to each other outside the cooling portion, the fluid to be cooled from a cooling load flowing in the circulation pipeline, a first heat exchanger provided in a portion of the circulation pipeline for fluid to be cooled which is located within the cavity, and a pump provided in the circulation pipeline for fluid to be cooled outside the cooling portion; a refrigerant circulation pipe connecting an exit of the exhaust pipe of the cyclone refrigeration device and the other end of refrigerant inflow pipe; a first compressor provided in the refrigerant circulation pipe to compress the gas-phase refrigerant exhausted from the exhaust pipe of the cyclone refrigeration device; first and second condensers provided in series downstream of the first compressor in the refrigerant circulation pipe so as to condense the gas-phase refrigerant compressed by the first compressor into the liquid-phase refrigerant; a second heat exchanger provided downstream of the first and second condensers in the refrigerant circulation pipe; a bypass line connecting a downstream side of the second heat exchanger and an upstream side of the first compressor in the refrigerant circulation pipe; a second decompression unit provided in the bypass line; an evaporator provided downstream of the second decompression unit in the bypass line; a first flow controller provided downstream of the connection point with an upstream end of the bypass line in the refrigerant circulation pipe; a second flow controller provided upstream of the second decompression unit in the bypass line; a third flow controller provided upstream of the connection point with a downstream end of the bypass line in the refrigerant circulation pipe; and a fourth flow controller provided downstream of the evaporator in the bypass line.
According to a preferred embodiment of the present invention, the first heat exchanger consists of a container made of heat conductor, the container having a fluid outlet and a fluid inlet and filled with the fluid to be cooled, wherein the circulation pipeline for fluid to be cooled consists of a discharge line for fluid to be cooled connected to the fluid outlet of the container at one end thereof and projecting from the container to the outside of the cooling portion, and a supply line for fluid to be cooled connected to the fluid inlet of the container at one end thereof and projecting from the container to the outside of the cooling portion, wherein the other end of the discharge line for fluid to be cooled and the other end of the supply line for fluid to be cooled are connected to each other through the cooling load, and the pump is provided in the discharge line for fluid to be cooled or the supply line for fluid to be cooled.
According to another preferred embodiment of the present invention, the cyclone refrigeration device further comprises a vortex flow control body arranged across the interior space of the cylindrical portion and the cavity of the cooling portion, the vortex flow control body having a columnar bottom portion, a frustoconical middle portion connecting to a top surface of the bottom portion and tapering upward from the bottom portion, and a columnar top portion connecting to a top surface of the middle portion and extending upward from the middle portion, wherein the vortex flow control body is provided with an axial through hole with circular cross section therein, the second vortex flow flowing into the through hole, the through hole spreading out toward the top surface of the vortex flow control body after tapering upward from the bottom surface of the vortex flow control body, wherein the vortex flow control body is supported coaxially to the cylindrical portion by the cooling portion and/or the cylindrical portion in a manner such that the bottom portion is located within the cavity and the middle portion across the cavity and the interior space and a certain space is formed under the bottom surface of the vortex control body.
According to further embodiment of the present invention, the interior space of the cylindrical portion is tapered downward.
According to further embodiment of the present invention, the refrigerant is carbon dioxide or water or ammonia.
In order to achieve this object, the present invention further provides a cascade heat pump system comprising a low-temperature side cycle and a high-temperature side cycle, wherein the low-temperature side cycle consists of the above cyclone heat recovery unit, and the second heat exchanger of the cyclone heat recovery unit forms a low-temperature side heat exchanger of a cascade heat exchanger.
In the above cascade heat pump system, preferably, the high-temperature side cycle includes a high-temperature side heat exchanger pairing with the second heat exchanger of the cyclone heat recovery unit to form the cascade heat exchanger; a high-temperature side refrigerant circulation pipe extending between an exit and an entrance of the high-temperature side heat exchanger; a second compressor provided downstream of the high-temperature side heat exchanger in the high-temperature side refrigerant circulation pipe; third and fourth condensers provided in series downstream of the second compressor in the high-temperature side refrigerant circulation pipe; and a third decompression unit provided downstream of the third and fourth condensers in the high-temperature side refrigerant circulation pipe.

EFFECT OF THE INVENTION

According to the present invention, the liquid-phase refrigerant condensed under high pressure is decompressed into the solid-gas two-phase refrigerant, and the solid-gas two-phase refrigerant flows downward into the interior space of the cylindrical portion while forming the first vortex flow and separating into the solid-phase refrigerant and the gas-phase refrigerant. The solid-phase refrigerant deposits in the cavity of the cooling portion on the one hand and the gas-phase refrigerant forms a second vortex flow rising from the bottom of the cavity through the inside space of the first vortex flow to flow out through the exhaust pipe on the other hand. Thereby the solid-phase refrigerant is prevented from adhering to and depositing in a refrigerant flow passage to block the refrigerant flow passage during operation of the refrigeration device.
Also, a flow passage for the fluid to be cooled is separated from the solid-phase refrigerant by circulating the fluid to be cooled in the circulation pipeline for fluid to be cooled and exchanging heat between the fluid to be cooled and the solid-phase refrigerant deposited in the cavity, and accordingly, the solid-phase refrigerant is prevented from adhering to and depositing in a flow passage for the fluid to be cooled to block the flow passage for the fluid to be cooled during operation of the refrigeration device.
Thereby the smooth and stable continuous operation of the refrigeration device is achieved.
Furthermore, according to the present invention, only the solid-phase refrigerant separated from the solid-gas two-phase refrigerant exchanges heat with the fluid to be cooled so that all of the sublimation heat of the solid-phase refrigerant is supplied to the fluid to be cooled and can be used to cool the fluid to be cooled. Consequently, the cooling capacity of the refrigeration device is greatly improved, compared with the conventional refrigeration device using the latent heat of the solid-phase refrigerant in the solid-gas two-phase state.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view schematically illustrating a configuration of a cyclone refrigeration device according to an embodiment of the present invention.
Fig. 2 is a view similar to Fig. 1 schematically illustrating a configuration of a cyclone refrigeration device according to another embodiment of the present invention.
Fig. 3 is a view schematically illustrating a configuration of a heat pump system not falling within the scope of the claims into which the cyclone refrigeration device of Fig. 1 as an evaporator is incorporated.
Fig. 4 is a Mollier diagram of the heat pump system of Fig. 3 in which CO₂ as a refrigerant is used.
Fig. 5 is a Mollier diagram of a variation of the heat pump system of Fig. 3 in which the cyclone refrigeration device of Fig. 2 is provided instead of the cyclone refrigeration device of Fig. 1 and CO₂ as a refrigerant is used.
Fig. 6 is a Mollier diagram of a case in which a well-known evaporator is provided instead of the cyclone refrigeration device and CO₂ as a refrigerant is used in the heat pipe system shown in Fig. 3.
Fig. 7 is a view schematically illustrating a configuration of a cyclone heat recovery unit provided with the cyclone refrigeration device shown in Fig. 1.
Fig. 8 is a view schematically illustrating a configuration of a cascade heat pump system into which the cyclone heat recovery unit shown in Fig. 7 is incorporated as a low-temperature side cycle.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the present invention will be explained below with reference to accompanying drawings.
Fig. 1 is a front view schematically illustrating a configuration of a cyclone refrigeration device according to an embodiment of the present invention.
Referring to Fig. 1, the cyclone refrigeration device of the cyclone heat recovery unit of the present invention comprises a cylindrical portion 1 extending vertically, an inner flange 2 provided at a top opening 1a of the cylindrical portion 1, an exhaust pipe 3 whose outer diameter corresponds to an opening diameter of the inner flange connected to the inner flange 2 at one end thereof in a manner such that the exhaust pipe protrudes upward from and coaxially with the top opening 1a of the cylindrical portion 1.
A structure of connecting the cylindrical portion 1 and the exhaust pipe 3 is not limited to this embodiment, and the connection may have any structure as long as the cylindrical portion vertically extends and is closed at a top end thereof and the exhaust pipe whose radius is smaller than the radius of the cylindrical portion is connected coaxially to the top end of the cylindrical portion and extended upward from the top end of the cylindrical portion.
Although, in this embodiment, an interior space 1b of the cylindrical portion 1 is tapered downward (the interior space 1b is formed so that inner diameter thereof gradually decreases downward), the inner diameter of the interior space 1b may be constant.
Also, a cooling portion 4 is connected to a bottom end of the cylindrical portion 1 and provided with a cavity 4a which communicates with the interior space 1b of the cylindrical portion 1.
The cylindrical portion 1 has a refrigerant inlet 1c at an upper portion of a side wall thereof. The refrigerant inlet 1c preferably extends tangentially to a cross section of the cylindrical portion 1.
A refrigerant inflow pipe 5 is connected to the refrigerant inlet 1c of the cylindrical portion 1 at one end 5a thereof. The refrigerant inflow pipe 5 receives supply of liquid-phase refrigerant condensed under high pressure at the other end 5b thereof. An expansion valve (decompression unit) 6 is provided in the refrigerant inflow pipe 5.
In this embodiment, a tank G as a supply source of liquid-phase refrigerant is connected to the other end 5b of the refrigerant inflow pipe 5.
Thus the liquid-phase refrigerant supplied to the refrigerant inflow pipe 5 is decompressed to form solid-gas two-phase refrigerant by the expansion valve 6, and the solid-gas two-phase refrigerant flows into the interior space 1b of the cylindrical portion 1 through the refrigerant inlet 1c and flows downward along an inner wall surface of the interior space 1b to form a first vortex flow.
In this case, the pressure outside the first vortex flow is greater than the pressure inside the first vortex flow, and this pressure difference between the outside and inside of the first vortex flow decreases from top to the bottom of the interior space 1b. Thereby the first vortex flow extends from the refrigerant inlet 1c of the cylindrical portion 1 to the cavity 4a of the cooling portion 4 and is maintained as it is.
The solid-gas two-phase refrigerant is separated from a solid-phase refrigerant S and a gas-phase refrigerant by the formation of the first vortex flow, and the solid-phase refrigerant S is deposited in the cavity 4a. On the other hand, the gas-phase refrigerant reaches the bottom of the cavity 4a, where the pressure difference between the outside and the inside of the first vortex flow is small so that the gas-phase refrigerant forms a second vortex flow rising through an inside space of the first vortex flow descending into the interior space 1b and flows out through the exhaust pipe 3.
In order to achieve this phase change of the refrigerant, it is required that the refrigerant used in the present invention can be maintained at pressure and temperature levels below the triple point thereof inside the refrigeration device. As a refrigerant satisfying this condition, for example, carbon dioxide (CO₂), water, ammonia and so on can be listed.
According to the present invention, the refrigeration device of the cyclone heat recovery unit of the present invention also comprises a circulation pipeline for fluid to be cooled 7 extending through the cavity 4a of the cooling portion 4. Both ends of the circulation pipeline for fluid to be cooled 7 are connected to each other outside the cooling portion 4, and the fluid to be cooled from a cooling load 9 flows in the circulation pipeline for fluid to be cooled 7. A heat exchanger 8 is provided in a portion of the circulation pipeline for fluid to be cooled 7 which is located within the cavity 4. The heat exchanger 8 performs heat exchange between the solid-phase refrigerant deposited in the cavity 4a and the fluid to be cooled.
In this embodiment, the heat exchanger 8 consists of a container made of heat conductor, the container having a fluid outlet 8a and a fluid inlet 8b and filled with the fluid to be cooled.
In this case, antifreeze, ethanol and so on can be used as the fluid to be cooled, and the container (heat exchanger) 8 is preferably made of a metal such as aluminum that has high thermal conductivity and is not easily affected by corrosion by the fluid to be cooled.
The circulation pipeline for fluid to be cooled 7 consists of a discharge line for fluid to be cooled 7a connected to the fluid outlet 8a of the container (heat exchanger) 8 at one end thereof and projecting from the container 8 to the outside of the cooling portion 4 through the cavity 4a, and a supply line for fluid to be cooled 7b connected to the fluid inlet 8b of the container 8 at one end thereof and projecting from the container 8 to the outside of the cooling portion 4 through the cavity 4a.
The other end of the discharge line for fluid to be cooled 7a and the other end of the supply line for fluid to be cooled 7b are connected to each other through the cooling load 9.
According to the present invention, a pump 10 is provided in the discharge line for fluid to be cooled 7a or the supply line for fluid to be cooled 7b. The fluid to be cooled is circulated by the pump 10 in the order of the container (heat exchanger) 8 -> the discharge line for fluid to be cooled 7a -> the cooling load 9 -> the supply line for fluid to be cooled 7b -> the container (heat exchanger) 8.
Thus in the cyclone refrigeration device, liquid-phase refrigerant condensed under high pressure is decompressed to form solid-gas two-phase refrigerant, and the solid-gas two-phase refrigerant flows downward into the interior space 1a of the cylindrical portion 1 while forming the first vortex flow and separating into the solid-phase refrigerant S and the gas-phase refrigerant. The solid-phase refrigerant S deposits in the cavity 4a of the cooling portion 4 on the one hand and the gas-phase refrigerant forms a second vortex flow rising from the bottom of the cavity 4a through the inside space of the first vortex flow to flow out through the exhaust pipe 3 on the other hand.
Then the solid-phase refrigerant S deposited in the cavity 4a is sublimated by the heat of the fluid to be cooled which is filled in the container (heat exchanger) 8, and the sublimation heat is supplied to the fluid to be cooled so that the cooled fluid to be cooled is supplied to the cooling load 9 through the discharge line for fluid to be cooled 7a.
According to this configuration, the descending vortex flow (first vortex flow) of the solid-gas two-phase refrigerant is generated in the interior space 1b of the cylindrical portion 1 so that the solid-gas two-phase refrigerant is separated into the solid-phase refrigerant S and the gas-phase refrigerant. Then the solid-phase refrigerant S deposits in the cavity 4a of the cooling portion 4, while the gas-phase refrigerant flows upward through the inside space of the descending vortex flow (first vortex flow) to flow out through the exhaust pipe 3. Thereby the solid-phase refrigerant S is prevented from adhering to and depositing in a refrigerant flow passage to block the refrigerant flow passage during operation of the refrigeration device.
Furthermore, a flow passage for the fluid to be cooled is separated from the solid-phase refrigerant S by circulating the fluid to be cooled in the circulation pipeline for fluid to be cooled 7 and exchanging heat between the fluid to be cooled and the solid-phase refrigerant S deposited in the cavity 4a, and accordingly, the solid-phase refrigerant S is prevented from adhering to and depositing in a flow passage for the fluid to be cooled to block the flow passage for the fluid to be cooled during operation of the refrigeration device.
Thereby the smooth and stable continuous operation of the refrigeration device is achieved.
In addition, according to the present invention, only the solid-phase refrigerant S separated from the solid-gas two-phase refrigerant exchanges heat with the fluid to be cooled so that all of the sublimation heat of the solid-phase refrigerant S is supplied to the fluid to be cooled and can be used to cool the fluid to be cooled. Consequently, the cooling capacity of the refrigeration device is greatly improved, compared with the conventional refrigeration device using the latent heat of the solid-phase refrigerant in the solid-gas two-phase state.
Fig. 2 is a view similar to Fig. 1 schematically illustrating a configuration of a cyclone refrigeration device of the cyclone heat recovery unit according to another embodiment of the present invention.
The embodiment of Fig. 2 differs from the embodiment of Fig. 1 only in that a structure for controlling the vortex flows is provided over the interior space 1b of the cylindrical portion 1 and the cavity 4a of the cooling portion 4. Therefore, in Fig. 2, the same structural elements as those shown in Fig. 1 are designated by the same reference numerals and the detailed description of them will be omitted in the following.
Referring to Fig. 2, in this embodiment, a vortex control body 11 is arranged across the interior space 1b of the cylindrical portion 1 and the cavity 4b of the cooling portion 4 and extends vertically.
The vortex flow control body 11 has a columnar bottom portion 11a, a frustoconical middle portion 11b connecting to a top surface of the bottom portion 11a and tapering upward from the bottom portion 11a, and a columnar top portion 11c connecting to a top surface of the middle portion 11b and extending upward from the middle portion 11b.
The vortex flow control body 11 is provided with an axial through hole 12 with circular cross section therein, and the second vortex flow flows into the through hole 12.
The through hole 12 tapers upward from a bottom surface 11e of the vortex flow control body 11 and then spreads out toward a top surface 11d of the vortex flow control body 11.
The through hole 12 functions as a diffuser.
The vortex flow control body 11 is supported coaxially to the cylindrical portion 1 by the cooling portion 4 and/or the cylindrical portion 1 through an appropriate support member (not shown) in a manner such that the bottom portion 11a is located within the cavity 4a and the middle portion 11b across the cavity 4a and the cylindrical portion 1 and a certain space is formed under the bottom surface 11e of the vortex control body 11.
The first vortex flow of the solid-gas two-phase refrigerant descending outside of the vortex control body 11 while the second vortex flow of the gas-phase refrigerant separated from the solid-gas two-phase refrigerant passes upward through the through hole 12 of the vortex flow control body 11 and pressurized by the diffuser function of the through hole during passage of the through hole.
According to this embodiment, the vortex flow control body 11 facilitates inward movement of the gas-phase refrigerant in the first vortex flow at the bottom of the interior space 1b and the cavity 4a and makes the second vortex flow of the gas-phase refrigerant more stable and stronger.
Thereby the collection efficiency of the solid-phase refrigerant S is higher than that of the embodiment shown in Fig. 1 and accordingly, the cooling capacity of the refrigeration device is improved.
Fig. 3 is a view schematically illustrating a configuration of a heat pump system, not falling within the scope of the claims, into which the cyclone refrigeration device of Fig. 1 as an evaporator is incorporated. In Fig. 3, the same structural elements as those shown in Fig. 1 are designated by the same reference numerals and the detailed description of them will be omitted in the following.
Referring to Fig. 3, the heat pump system 16 comprises the cyclone refrigeration device shown in Fig. 1, and a refrigerant circulation pipe 15 connecting an exit of the exhaust pipe 3 of the cyclone refrigeration device and the other end 5b of refrigerant inflow pipe 5.
The heat pump system 16 further comprises a compressor 13 provided in the refrigerant circulation pipe 15 to compress the gas-phase refrigerant exhausted from the exhaust pipe 3 of the cyclone refrigeration device, and a condenser 14 arranged downstream of the compressor 13 in the refrigerant circulation pipe 15 to condense the gas-phase refrigerant compressed by the compressor 13 into the liquid-phase refrigerant.
Fig. 4 is a Mollier diagram of the heat pump system 16 when CO₂ is used as a refrigerant.
Next, the operation of the heat pump system 16 will be described with reference to Figs. 3 and 4.
A gas-phase CO₂ taken into the compressor 13 through the refrigerant circulation pipe 15 is compressed by the compressor 13 (D -> A in Fig. 4) to form high-pressure gas-phase CO₂, and the high-pressure gas-phase CO₂ is supplied to the condenser 14 through the refrigerant circulation pipe 15.
After that, in the condenser 14, the gas-phase CO₂ is cooled under high pressure to form a liquid-phase CO₂ (A -> B in Fig. 4), and the high-pressure liquid-phase CO₂ is supplied to the expansion valve 6 through the refrigerant inflow pipe 5.
The high-pressure liquid-phase CO₂ is expanded and decompressed by the expansion valve 6 to form a solid-gas two-phase CO₂ (B -> C in Fig. 4), and the solid-gas two-phase CO₂ flows into the interior space 1b of the cylindrical portion 1 of the evaporator (cyclone refrigeration device) through the refrigerant inlet 1c of the evaporator (cyclone refrigeration device).
The solid-gas two-phase CO₂ forms the first vortex flow descending into the interior space 1b and separates into a solid-phase CO₂ and a gas-phase CO₂ (C -> E (corresponding to a separation process of the solid-phase CO₂ from the solid-gas two-phase CO₂) and C -> D (corresponding to a separation process of the gas-phase CO₂ from the solid-gas two-phase CO₂) in Fig. 4).
The solid-phase CO₂ deposits in the cavity 4a of the cooling portion 4 of the evaporator (cyclone refrigeration device) while the gas-phase CO₂ forms the second vortex flow rising through the inside space of the first vortex flow and is taken from the exhaust pipe 3 into the compressor 13 through the refrigerant circulation pipe 15.
The solid-phase CO₂ deposited in the cavity 4a of the evaporator (cyclone refrigeration device) is sublimated by the heat of the fluid to be cooled (E -> D in Fig. 4), and this sublimation heat is supplied to the fluid to be cooled.
Fig. 6 is a Mollier diagram of a case in which a well-known evaporator is provided instead of the cyclone refrigeration device of the cyclone heat recovery unit of the present invention and CO₂ as a refrigerant is used.
In Fig. 6, D -> A corresponds to a compression process in the compressor 13, A -> B corresponds to a condensation process in the condenser 14, B -> C corresponds to an expansion process in the expansion valve (decompression unit), and C -> D corresponds to an evaporation process in the evaporator.
As is obvious from the comparison between the graph of Fig. 4 and the graph of Fig. 6, according to the heat pump system 16, the enthalpy obtained in the evaporation process in the evaporator (cyclone refrigeration device) is greatly increased compared to the conventional heat pump system.
This is due to the following:
In the conventional heat pump system, the heat exchange is done between a solid-gas two-phase CO₂ and fluid to be cooled so that the fluid to be cooled by the latent heat of the solid-phase CO₂ in the solid-gas two-phase state, and accordingly, heat of sublimation of the solid-phase CO₂ cannot be efficiently used to cool the fluid to be cooled. In contrast, according to the present invention, only the solid-phase CO₂ separated from the solid-gas two-phase CO₂ exchanges heat with the fluid to be cooled so that the heat of sublimation of the solid-phase CO₂ is supplied to the fluid to be cooled, and accordingly, all of the sublimation heat of the solid-phase CO₂ can be used to cool the fluid to be cooled.
Consequently, according to the heat pump system 16, the cooling capacity of the heat pump system is greatly increased.
Fig. 5 is a Mollier diagram of a variation of the heat pump system 16 of Fig. 3 in which the cyclone refrigeration device of Fig. 2 is provided instead of the cyclone refrigeration device of Fig. 1.
In Fig. 5, D -> A corresponds to a compression process in the compressor 13, A -> B corresponds to a condensation process in the condenser 14, B -> C corresponds to an expansion process in the expansion valve (decompression unit) 6, C -> E corresponds to a separation process of the solid-phase refrigerant from the solid-gas two-phase refrigerant S in the evaporator (cyclone refrigeration device), C -> D corresponds to a separation process of the gas-phase refrigerant from the solid-gas two-phase refrigerant in the evaporator (cyclone refrigeration device), and E -> D corresponds to an evaporation process of the solid-phase refrigerant S in the evaporator (cyclone refrigeration device).
As is obvious from the comparison between the graph of Fig. 5 and the graph of Fig. 4, in the embodiment of Fig. 5, the pressure value at the point D is higher than in the embodiment of Fig. 4.
This is due to the diffuser action of the through hole 12 of the vortex flow control body 11.
Thereby the effect that the suction pressure of the compressor 13 rises and the operating efficiency of the compressor 13 improves is obtained.
While a preferred embodiment of a cyclone refrigeration device of the cyclone heat recovery unit of the present invention has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein.
For example, although one compressor is used alone in the compression process of CO₂ (D -> A) in the above embodiment, it is possible to provide a compressor composed of a low pressure compressor and a high pressure compressor which are connected in series, and an inter cooler arranged between the low pressure and high pressure compressors so as to compress CO₂ in two stages.
According to this configuration, a gas-phase CO₂ can be easily compressed to saturation or supercritical pressure.
Also, it is possible in the condensation process (A -> B) of CO₂ in the above embodiment to provide a cascade heat exchanger so as to cool and condense the high-pressure gas-phase CO₂ via the cascade heat exchanger.
According to this configuration, the cooling capacity of the condenser improves so that the high-pressure gas-phase CO₂ can be cooled to lower temperature in one stage.
Fig. 7 is a view schematically illustrating a configuration of a cyclone heat recovery unit provided with the cyclone refrigeration device shown in Fig. 1.
In Fig. 7, the same structural elements as those shown in Fig. 1 are designated by the same reference numerals and the detailed description of them will be omitted in the following.
Referring to Fig. 7, a cyclone heat recovery unit 17 of the present invention comprises the cyclone refrigeration device shown in Fig. 1, and a refrigerant circulation pipe 18 connecting an exit of the exhaust pipe 3 of the cyclone refrigeration device and the other end 5b of refrigerant inflow pipe 5.
A compressor 19 is provided in the refrigerant circulation pipe 18 so as to compress a gas-phase refrigerant exhausted from the exhaust pipe 3 of the cyclone refrigeration device, and first and second condensers 20, 21 are provided in series downstream of the compressor 19 in the refrigerant circulation pipe 18 so as to condense the gas-phase refrigerant compressed by the compressor 18 into a liquid-phase refrigerant.
Further, a heat exchanger 22 is provided downstream of the first and second condensers 20, 21 in the refrigerant circulation pipe 18.
A bypass line 23 is provided in the refrigerant circulation pipe 18 so as to connect a downstream side of the heat exchanger 22 and an upstream side of the compressor 18.
An expansion valve (decompression unit) 24 is provided in the bypass line 23 and an evaporator 25 is provided downstream of the expansion valve 24 in the bypass line 23.
A first flow controller 27 is provided downstream of the connection point 26 with an upstream end of the bypass line 23 in the refrigerant circulation pipe 18, and a second flow controller 28 is provided upstream of the expansion valve 24 in the bypass line 23.
A third flow controller 30a is provided upstream of the connection point 29 with a downstream end of the bypass line 23 in the refrigerant circulation pipe 18, and a fourth flow controller 30b is provided downstream of the evaporator 25 in the bypass line 23.
The third and fourth flow controllers 30a, 30b are primarily intended for pressure control.
That is to say, in this embodiment, when CO₂ is used as a refrigerant, the cyclone refrigeration device operates under the pressure condition below the triple point at which CO2 enters a solid-gas two-phase state while the evaporator 25 operates under the pressure condition above the triple point at which CO₂ enters a gas-liquid two-phase state and therefore, the third and fourth flow controllers 30a, 30b operate in such a way that the above pressure conditions are satisfied.
In this embodiment, the fluid to be cooled which exchanges heat with the solid-phase refrigerant S in the heat exchanger 8 of the cyclone refrigeration device is preferably low-temperature refrigerant (carbon dioxide, ethanol and helium and so on).
A lower temperature cold source can be obtained by using the low temperature refrigerant as fluid to be cooled.
In order to make the cyclone heat recovery unit 17 operate more stably, it is preferable to maintain the pressure in the cyclone refrigeration device at 1 MPa or less. This is easily achieved by sequence control of the compressor 19.
According to this invention, it is possible to divide some of the liquid-phase refrigerant flowing through the refrigerant circulation pipe 18 into the bypass line 23 so as to operate the cyclone refrigeration device and the evaporator 25 at the same time, or it is possible to stop the supply of the liquid-phase refrigerant to the bypass line 23 so as to operate only the cyclone refrigeration device, or it is possible to stop the supply of the liquid-phase refrigerant to the cyclone refrigeration device so as to operate only the evaporator 25.
Thereby the range of temperature of recoverable heat is wider than that of the embodiment shown in Fig. 1.
Fig. 8 is a view schematically illustrating a configuration of a cascade heat pump system into which the cyclone heat recovery unit shown in Fig. 7 is incorporated as a low-temperature side cycle.
In Fig. 8, the same structural elements as those shown in Fig. 7 are designated by the same reference numerals and the detailed description of them will be omitted in the following.
As shown in Fig. 8, a cascade heat pump system 31 comprises a low-temperature side cycle 32 and a high-temperature side cycle 33, and the low-temperature side cycle consists of the cyclone heat recovery unit 17 shown in Fig. 7.
In this case, the heat exchanger 22 of the cyclone heat recovery unit 17 forms a low-temperature side heat exchanger 35 of a cascade heat exchanger 34 of the cascade heat pump system 31.
The high-temperature side cycle 33 includes a high-temperature side heat exchanger 36 pairing with the low-temperature side heat exchanger 35 to form the cascade heat exchanger 34, a high-temperature side refrigerant circulation pipe 37 extending between an exit 36a and an entrance 36b of the high-temperature side heat exchanger 36, a compressor 38 provided downstream of the high-temperature side heat exchanger 36 in the high-temperature side refrigerant circulation pipe 37, third and fourth condensers 39, 40 provided in series downstream of the compressor 38 in the high-temperature side refrigerant circulation pipe 37, and an expansion valve (decompression unit) 41 provided downstream of the third and fourth condensers 39, 40 in the high-temperature side refrigerant circulation pipe 37.

DESCRIPTION OF REFERENCE NUMERALS

1: Cylindrical portion
1a: Top opening
1b: Interior space
1c: Refrigerant inlet
2: Inner flange
3: Exhaust pipe
4: Cooling portion
4a: Cavity
5: Refrigerant inflow pipe
5a: One end
5b: The other end
6: Expansion valve (Decompression unit)
7: Circulation pipeline for liquid to be cooled
7a: Discharge line for fluid to be cooled
7b: Supply line for fluid to be cooled
8: Heat exchanger
8a: Fluid outlet
8b: Fluid inlet
9: Cooling load
10: Pump
11: Vortex flow control body
11a: Bottom portion
11b: Middle portion
11c: Top portion
11d: Top surface
11e: Bottom surface
12: Through hole
13: Compressor
14: Condenser
15: Refrigerant circulation pipe
16: Heat pump system
17: Cyclone heat recovery unit
18: Refrigerant circulation pipe
19: Compressor
20: First condenser
21: Second condenser
22: Heat exchanger
23: Bypass line
24: Expansion valve (Decompression unit)
25: Evaporator
26: Connection point
27: First flow controller
28: Second flow controller
29: Connection point
30a: Third flow controller
30b: Fourth flow controller
31: Cascade heat pump system
32: Low-temperature side cycle
33: High-temperature side cycle
34: Cascade heat exchanger
35: Low-temperature side heat exchanger
36: High-temperature side heat exchanger
36a: Exit
36b: Entrance
37: High-temperature side refrigerant circulation pipe
38: Compressor
39: Third condenser
40: Fourth condenser
41: Expansion valve (decompression unit)
S: Solid-phase refrigerant

Claims

A cyclone heat recovery unit (17) comprising:
a cyclone refrigeration device,

the cyclone refrigeration device comprising

a cylindrical portion (1) vertically extending and closed at a top end thereof,

an exhaust pipe (3) whose radius is smaller than the radius of the cylindrical portion (1) connected coaxially to the top end of the cylindrical portion (1) in fluid connection with an interior space (1b) of the cylindrical portion (1) and extended upward from the top end of the cylindrical portion (1),

a cooling portion (4) connected to a bottom end of the cylindrical portion (1) and provided with a cavity (4a) which communicates with the interior space (1b) of the cylindrical portion (1),

the cylindrical portion (1) having a refrigerant inlet (1c) at an upper portion of a side wall thereof;

a refrigerant inflow pipe (5) connected to the refrigerant inlet (1c) at one end (5a) thereof and receiving a supply of liquid-phase refrigerant compressed under high pressure at the other end thereof, and

a first decompression unit (6) provided in the refrigerant inflow pipe (5),

wherein the liquid-phase refrigerant supplied to the refrigerant inflow pipe (5) is decompressed to form solid-gas two-phase refrigerant by the first decompression unit (6), and the solid-gas two-phase refrigerant flows downward into the interior space (1b) of the cylindrical portion (1) while forming a first vortex flow and separating into solid-phase refrigerant and gas-phase refrigerant, and the solid-phase refrigerant (S) deposits in the cavity (4a) on the one hand and the gas-phase refrigerant forms a second vortex flow rising from the bottom of the cavity (4a) through an inside space of the first vortex flow to flow out of the exhaust pipe (3) on the other hand,

wherein the cyclone refrigeration device further comprises

a circulation pipeline (7) for fluid to be cooled extending through the cavity (4a) of the cooling portion (4), both ends of the circulation pipeline (7) being connected to each other outside the cooling portion (4), the fluid to be cooled from a cooling load (9) flowing in the circulation pipeline (7),

a first heat exchanger (8) provided in a portion of the circulation pipeline (7) for fluid to be cooled which is located within the cavity (4a), and

a pump (10) provided in the circulation pipeline (7) for fluid to be cooled outside the cooling portion (4);

a refrigerant circulation pipe (18) connecting an exit of the exhaust pipe (3) of the cyclone refrigeration device and the other end (5b) of refrigerant inflow pipe (5) ;

a first compressor (19) provided in the refrigerant circulation pipe (18) to compress the gas-phase refrigerant exhausted from the exhaust pipe (3) of the cyclone refrigeration device;

first and second condensers (20, 21) provided in series downstream of the first compressor (19) in the refrigerant circulation pipe (18) so as to condense the gas-phase refrigerant compressed by the first compressor (19) into the liquid-phase refrigerant;

a second heat exchanger (22) provided downstream of the first and second condensers (20, 21) in the refrigerant circulation pipe (18);

a bypass line (23) connecting a downstream side of the second heat exchanger (22) and an upstream side of the first compressor (19) in the refrigerant circulation pipe (18) ;

a second decompression unit (24) provided in the bypass line (23);

an evaporator (25) provided downstream of the second decompression unit (24) in the bypass line (23);

a first flow controller (27) provided downstream of the connection point (26) with an upstream end of the bypass line (23) in the refrigerant circulation pipe (18);

a second flow controller (28) provided upstream of the second decompression unit (24) in the bypass line (23);

a third flow controller (30a) provided upstream of the connection point (29) with a downstream end of the bypass line (23) in the refrigerant circulation pipe (18); and

a fourth flow controller (30b) provided downstream of the evaporator (25) in the bypass line (23).
The cyclone heat recovery unit (17) according to Claim 1, wherein the first heat exchanger (8) consists of a container made of heat conductor, the container (8) having a fluid outlet (8a) and a fluid inlet (8b) and filled with the fluid to be cooled,
wherein the circulation pipeline (7) for fluid to be cooled consists of

a discharge line (7a) for fluid to be cooled connected to the fluid outlet (8a) of the container (8) at one end thereof and projecting from the container (8) to the outside of the cooling portion (4), and

a supply line (7b) for fluid to be cooled connected to the fluid inlet (8b) of the container (8) at one end thereof and projecting from the container (8) to the outside of the cooling portion (4),

wherein the other end of the discharge line (7a) for fluid to be cooled and the other end of the supply line (7b) for fluid to be cooled are connected to each other through the cooling load (9), and the pump (10) is provided in the discharge line (7a) for fluid to be cooled or the supply line (7b) for fluid to be cooled.
The cyclone heat recovery unit (17) according to Claim 1, wherein the cyclone refrigeration device further comprises
a vortex flow control body (11) arranged across the interior space (1b) of the cylindrical portion (1) and the cavity (4a) of the cooling portion (4) and extended vertically, the vortex flow control body (11) having

a columnar bottom portion (11a),

a frustoconical middle portion (11b) connecting to a top surface of the bottom portion (11a) and tapering upward from the bottom portion (11a), and

a columnar top portion (11c) connecting to a top surface of the middle portion (11b) and extending upward from the middle portion (11b),

wherein the vortex flow control body (11) is provided with an axial through hole (12) with circular cross section therein, the second vortex flow flowing into the through hole (12), the through hole spreading out toward the top surface (11d) of the vortex flow control body (11) after tapering upward from the bottom surface (11e) of the vortex flow control body (11),

wherein the vortex flow control body (11) is supported coaxially to the cylindrical portion (1) by the cooling portion (4) and/or the cylindrical portion (1) in a manner such that the bottom portion (11a) is located within the cavity (4a) and the middle portion (11b) is located across the cavity (4a) and the interior space (1b) and a certain space is formed under the bottom surface (11e) of the vortex control body (11).
The cyclone heat recovery unit (17) according to Claim 1, wherein the interior space (1b) of the cylindrical portion (1) is tapered downward.
The cyclone heat recovery unit (17) according to Claim 1, wherein the refrigerant is carbon dioxide or water or ammonia.
A cascade heat pump system (31) comprising a low-temperature side cycle (32) and a high-temperature side cycle (33),
wherein the low-temperature side cycle (32) consists of the cyclone heat recovery unit (17) according to any one of Claims 1 to 5, and the second heat exchanger (22) of the cyclone heat recovery unit (17) forms a low-temperature side heat exchanger (35) of a cascade heat exchanger (34).
The cascade heat pump system (31) according to Claim 6, wherein the high-temperature side cycle (33) includes
a high-temperature side heat exchanger (36) pairing with the second heat exchanger (22) of the cyclone heat recovery unit (17) to form the cascade heat exchanger (34) ;

a high-temperature side refrigerant circulation pipe (37) extending between an exit (36a) and an entrance (36b) of the high-temperature side heat exchanger (36);

a second compressor (38) provided downstream of the high-temperature side heat exchanger (36) in the high-temperature side refrigerant circulation pipe (37);

third and fourth condensers (39, 40) provided in series downstream of the second compressor (38) in the high-temperature side refrigerant circulation pipe (37); and

a third decompression unit (41) provided downstream of the third and fourth condensers (39,40) in the high-temperature side refrigerant circulation pipe (37) .