Patent Application
20130305742
1. Field of the Invention
The present invention relates to a refrigeration method and apparatus in the field of refrigeration and cryogenic engineering, and especially to a refrigeration method and apparatus combining magnetic refrigeration and gas-based regenerative refrigeration. Namely, the present invention realizes efficient composite refrigeration of magnetic refrigeration and gas-based regenerative refrigeration by replacing part of or all of the conventional regenerator fillers in a gas-based regenerative refrigerator with the magnetic refrigeration materials, disposing the magnetic regenerators formed in such way in a magnetic field with controllable and changeable field strength and performing effective coupling between the working sequence of the gas-based regenerative refrigerator and the magnetic field changing sequence.
2. Description of the Related Art
In terms of basic principle, magnetic refrigeration and gas-based regenerative refrigeration are two different refrigeration technologies respectively.
Magnetic refrigeration technology implements refrigeration based on the physical phenomenon that heat is released by the magnetic material to the outside during the magnetization and is absorbed by the magnetic material from the outside during demagnetization. The study on magnetic refrigeration dates back to about 120 years ago. In 1881, Warburg first observed the heating effect of the metal iron in an applied magnetic field. In 1895, P. Langeviz discovered the magnetocaloric effect. Two scientists, Debye (in 1926) and Giaugue (in 1927), concluded that refrigeration can be realized by adiabatic demagnetization. After that, due to the significant progress on the magnetic refrigeration materials (magnetocaloric materials) of paramagnetic salts, the adiabatic demagnetization refrigeration technology developed rapidly in the ultra-low temperature range (˜10−6K) and low temperature range (below 15 K) after 1933. The discovery of Gd magnetocaloric effect and first realization of room temperature magnetic refrigeration by Brown in 1976 inspired people's interest in the room temperature magnetic refrigeration. Theoretically, magnetic refrigeration could be applied to any temperature range, but due to the limitation of magnetic refrigeration materials magnet technology and engineering technologies, the overall progress on the room temperature magnetic refrigeration is relatively slow. With the proposing of Active Magnetic Regenerator (AMR) and the progresses on room temperature magnetic refrigeration materials and systems by AMES national laboratory and Astronautics Corporation of America in the late 1990s, the magnetic refrigeration technology again attracts extensive attention.
Gas-based regenerative refrigeration is based on compression and expansion of working fluid under oscillating flow conditions, and is mainly used to obtain small or medium scale refrigerating capacity at low temperatures. Ever since Stirling cycle was put forward in 1816, after long-term development, the gas-based regenerative refrigeration have been developed into various forms of refrigerator such as Stirling refrigerator, Vuilleumier (VM) refrigerator, Gifford-McMahon (G-M) refrigerator, Solvay refrigerator, pulse tube (ST) refrigerator and thermoacoustic refrigerator. Although these refrigerators vary in the specific structure, all of them could be viewed as including three major parts: a pressure wave generator, regenerator and phase difference adjusting mechanism for adjusting phase difference between the pressure wave and mass flow rate (as shown
The magnetic refrigeration generally is based on the following three technologies: the magnetic refrigeration materials, magnets and the thermal engineering system. Advances in the magnetic refrigeration materials have been impressive. However, due to limited heat transfer coefficient and relatively small magnetocaloric temperature change (especially with less strong magnets), the temperature difference between heat transfer fluid and materials imposes strong adverse influence on the practical thermodynamic efficiency of the magnetic refrigerator. For this reason, the practical thermodynamic efficiency of the magnetic refrigerator is still very low although the intrinsic thermodynamic efficiency of the magnetic refrigeration is very high. In addition, the magnetic refrigerator often requires a complicated driving mechanism due to requirement of both high intensity changing magnetic field and heat transfer fluid with changing flow direction.
S. Jeong et al. in 1994 (Adv. Cryo. Engi. 39B) reported a magnetic refrigeration experimental system based on Stirling cycle. The concept of combining magnetic refrigeration and Stirling cycle was mentioned in the report. However, it is found after careful analysis of the report that the system is just an AMR magnetic refrigeration system based on Stirling thermodynamic cycle without real combination of magnetic refrigeration and gas-based regenerative refrigeration, let alone mentioning the use of permanent magnets of low energy consumption which can generate periodically-changing high intensity magnetic field conveniently.
G. F. Nellis et al. in 1998 (Adv. Cryo. Engi. 43) reported a magnetic refrigeration experimental system based on G-M cycle. The concept of combining magnetic refrigeration and G-M cycle was mentioned in the report. However, it is found after careful analysis of the report that the system is just an AMR magnetic refrigeration system based on G-M thermodynamic cycle, without real combination of magnetic refrigeration and gas-based regenerative refrigeration, let alone mentioning the use of permanent magnets of low energy consumption which can generate periodically-changing high intensity magnetic field conveniently.
Robert Schauwecker et al. proposed “a hybrid heat pump/refrigerator with magnetic cooling stage” (US 2007/0186560 A1). Although the “hybrid” of “gas refrigerator” and “magnetic refrigeration” is mentioned in the patent, the “gas refrigerator” and “magnetic refrigeration” are independent processes in the cycle and are only continuous in time. Actually, what the patent have achieved is only an “internal cascade” of “gas refrigerator” and “magnetic refrigeration”, instead of a real combination of gas-based regenerative refrigeration and magnetic refrigeration. In addition, the patent mentions several methods for changing magnetic field at the locations of magnetocaloric materials. Although the implementation methods are not described in detail, it can be obtained from the analysis of the description that there are many technical difficulties in implementing the methods (either requiring a complicated magnet and driving mechanism, or causing huge energy consumption). Thus, the methods cannot meet practical requirements.
This present invention aims to provide a refrigeration method and apparatus combining magnetic refrigeration and gas-based regenerative refrigeration. Namely, The present invention realizes efficient combination of magnetic refrigeration and gas-based regenerative refrigeration by replacing part of or all of the conventional regenerator fillers in a gas-based regenerative refrigerator with appropriate magnetic refrigeration materials, disposing the magnetic regenerators formed in such way in a magnetic field with controllable and changeable field strength and performing effective coupling between the working sequence of the gas-based regenerative refrigerator and magnetic field changing sequence.
The technical solutions of the present invention are as follows.
The present invention provides a refrigeration method combining magnetic refrigeration and gas-based regenerative refrigeration, which includes: replacing part of or all of regenerators in a gas-based regenerative refrigerator with magnetic regenerators, wherein part of or all of fillers in the magnetic regenerators are magnetic refrigeration materials to form magnetic regenerators with the same operating temperature ranges as that of the corresponding regenerators in the gas-based regenerative refrigerator; disposing the magnetic regenerators respectively in magnet assemblies for generating controllable and periodically-changing field strength, and performing coupling control on working sequence of the gas-based regenerative refrigerator and magnetic field changing sequence of the magnet assemblies for generating controllable and changeable field strength, to realize combination of magnetic refrigeration and gas-based regenerative refrigeration.
The present invention further provides a refrigeration apparatus combining magnetic refrigeration and gas-based regenerative refrigeration, which includes: a pressure wave generator 1, m regenerators, m phase difference adjusting mechanism, j magnet assemblies for generating controllable and changeable field strength and a coupling control system 5 for performing coupling control on working sequence of a gas-based regenerative refrigerator and magnetic field changing sequence,. wherein m is an integer between 1 and 5, and j<=m; part of or all of the m regenerators are magnetic regenerators; and part of or all of fillers in the magnetic regenerators are magnetic refrigeration materials; magnetic refrigeration temperature ranges of the magnetic refrigeration materials in the magnetic regenerators are the same as the corresponding temperature ranges of locations of the magnetic regenerators in the gas-based regenerative refrigerator;
The above components are connected in the following manner: the pressure wave generator 1 is connected via a fluid flow pipe with one end of a first stage gas-based regenerative refrigerator consisting of a first stage regenerator 21 and a first stage phase difference adjusting mechanism 31 for adjusting phase difference between pressure wave and mass flow rate; and the other end of the first stage gas-based regenerative refrigerator is connected with one end of a lower stage gas-based regenerative refrigerator via a fluid flow pipe, and so on until the last stage; the magnetic regenerators are respectively disposed in the corresponding magnet assemblies for generating controllable and periodically-changing field strength; and the coupling control system 5 for performing coupling control on working sequence of the gas-based regenerative refrigerator and magnetic field changing sequence is respectively connected with the pressure wave generator, phase difference adjusting mechanism and magnet assemblies for generating controllable and changeable field strength via a signal transmission cable and/or pipe and/or mechanical device;
input signals of the coupling control system 5 are characteristic parameters of the working sequence of the pressure wave generator 1 and/or characteristic parameters of the working sequence of respective phase difference adjusting mechanisms; and output signals of the coupling control system 5 are signals for controlling the magnet assemblies for generating controllable and changeable field strength.
The gas-based regenerative refrigerator is a Stirling refrigerator, Vuilleumier (VM) refrigerator, Gifford-McMahon (G-M) refrigerator, Solvay (SV) refrigerator, pulse tube refrigerator or thermoacoustic refrigerator.
The magnet assemblies generate controllable and changeable field strength based on superimposition of magnetic vectors through relative movement of two permanent magnets.
The refrigeration apparatus is a combined composite refrigeration system of magnetic refrigeration and gas-based regenerative refrigeration, which is formed by combining i identical refrigeration apparatuses combining magnetic refrigeration and gas-based regenerative refrigeration according to working sequence phase angle differences θ; wherein the working sequence phase angle differences θ are identical and equal to 360°/i or different from each other.
Through analysis, it can be obtained that, if a high intensity magnetic field of low energy consumption can be obtained, efficient combination of magnetic refrigeration and gas-based regenerative refrigeration can be completely realized in theory by replacing conventional regenerator fillers in a gas-based regenerative refrigerator with appropriate magnetic refrigeration materials, disposing the magnetic regenerators formed in such way in a magnetic field with controllable and changeable field strength and performing effective coupling between working sequence of the gas-based regenerative refrigerator and magnetic field changing sequence. From the perspective of thermodynamics, the above combination can completely blend the magnetic refrigeration and gas-based regenerative refrigeration in the whole cycle by the magnetic regenerators, and it is difficult to distinguish the magnetic refrigeration process from the gas-based regenerative refrigeration process. This combination not only can solve the problem of low efficiency of the pure magnetic refrigerator (the intrinsic efficiency of the combination is higher than that of the two independent refrigeration methods), but also can solve the problem of requiring a complicated heat transfer fluid driving mechanism in the pure magnetic refrigerator by sharing the working fluid between the gas-based regenerative refrigeration and magnetic refrigeration. In addition, due to the progresses on permanent magnet technology providing changeable magnetic fields, the high intensity magnetic field of low energy consumption which can be conveniently and periodically changed is no longer a technical bottleneck, which make it more feasible to implement the combination of gas-based regenerative refrigeration and magnetic refrigeration technically.
For a single magnet, to realize the change of magnetic field strength, it is usually required to input energy when the magnetic field strength is increased and release energy when the magnetic field strength is decreased, although this process is reversible, it is difficult to completely store and release the energy of this process technically, however this problem can be solved in the following way: combining multiple identical refrigeration apparatuses combining magnetic refrigeration and gas-based regenerative refrigeration according to certain working sequence phase angle difference to form a combined composite refrigeration system of magnetic refrigeration and gas-based regenerative refrigeration, in this way, energy storage/release between different magnet assembles for generating controllable and changeable field strength can be realized through working sequence differences of different magnet assembles in energy storage/release processes, thereby further increasing the composite refrigeration efficiency of the refrigeration apparatus of the present invention.
The refrigeration apparatus and method combining magnetic refrigeration and gas-based regenerative refrigeration of the present invention have the following advantages:
magnetic refrigeration and gas-based regenerative refrigeration are two different refrigeration methods, although both have high intrinsic thermodynamic efficiency, there are corresponding technical problems with both refrigeration methods. Especially, limited by the characteristics of the existing materials and requirement of the complicated heat transfer fluid driving mechanism, the actual efficiency of the magnetic refrigeration is still low and the mechanism is complicated. Through the present invention, the following advantages are obtained:
1. the present invention can solve the problem of low actual efficiency of the pure magnetic refrigerator, thereby improving the refrigeration efficiency significantly;
2. the present invention can solve the problem of requiring a complicated heat transfer fluid driving mechanism in the pure magnetic refrigerator by sharing the working fluid between gas-based regenerative refrigeration and magnetic refrigeration;
3. a novel refrigeration method with high intrinsic thermodynamic efficiency can be achieved by replacing the conventional regenerator fillers with magnetic refrigeration materials, the intrinsic efficiency of the novel refrigeration method is higher than that of the pure magnetic refrigeration method and the pure gas-based regenerative refrigeration method without an obvious increase of complexity of the whole system.
The present invention will be further illustrated in combination with accompanying drawings and embodiments.
The gas-based regenerative refrigerator may be Stirling refrigerator, VM refrigerator, G-M refrigerator, SV refrigerator, pulse tube refrigerator or thermoacoustic refrigerator.
Part of or all of m regenerators are magnetic regenerators filled with magnetic refrigeration materials. The magnetic refrigeration temperature ranges of the magnetic refrigeration materials in the magnetic regenerators are the same as the corresponding temperature ranges of locations of the magnetic regenerators in the gas-based regenerative refrigerator.
The magnetic regenerators are respectively disposed in the magnet assemblies for generating controllable and periodically-changing field strength, and the magnet assemblies generate controllable and changeable field strength based on the superimposition of magnetic vectors through relative movement of two permanent magnets. The input signals of the coupling control system 5 are characteristic parameters of the working sequence of the pressure wave generator 1 and/or characteristic parameters of the working sequence of part/all of the phase difference adjusting mechanisms 3, and the output signals of the coupling control system 5 are signals for controlling the change of magnetic field of the magnet assemblies for generating controllable and changeable field strength.
Embodiment 1: a refrigeration system combining magnetic refrigeration and 5-stage gas-based Stirling refrigeration with a refrigeration temperature of 5K and an ambient temperature of 300K
For each regenerator, 10 magnetic refrigeration materials with Curie temperatures or equivalent Curie temperatures ranging from 300K to 5K (the interval between respective Curie temperatures or equivalent Curie temperatures is about 6K) are selected, and the permanent magnet assembly 4 for generating controllable and changeable magnetic field strength is a permanent magnet assembly for generating periodically-changing magnetic field strength, which consists of two permanent magnets arranged co-axially and rotating relatively (as shown in
Each magnetic regenerator is formed by filling 10 magnetic refrigeration materials into the magnetic regenerator in a descending order according to the Curie temperatures or equivalent Curie temperatures of the 10 magnetic materials, and has the same operating temperature range as that of the corresponding regenerator in the gas-based regenerative refrigerator; the input signals of the sequence coupling controller 5 are the movement signals of the compression piston in the pressure wave generator (compression chamber) 1; the output signals of the sequence coupling controller 5 are relative movement signals for controlling the change of magnetic field of the permanent magnet assemblies for generating controllable and changeable field strength; and the flow of the working fluid in the composite refrigeration system is basically the same as that of conventional 5-stage gas-based Stirling refrigeration. This embodiment realizes the combination of magnetic refrigeration and 5-stage gas-based regenerative refrigeration by introducing the magnetic regenerators, permanent magnet assemblies for generating controllable and changeable field strength and the sequence coupling controller 5; the composite refrigeration system formed in such way can at least double the refrigeration capacity at 5K with nearly no increase on energy consumption.
Embodiment 2: a refrigeration system combining magnetic refrigeration and 5-stage gas-based Stirling refrigeration with a refrigeration temperature of 5K and an ambient temperature of 300K
6 magnetic refrigeration materials with Curie temperatures or equivalent Curie temperatures ranging from about 30K to about 5K (the interval between respective Curie temperatures or equivalent Curie temperatures is about 5K) are selected, and the magnet assembly 4 for generating controllable and changeable field strength is a permanent magnet assembly for generating periodically-changing field strength, which consists of two permanent magnets arranged co-axially and rotating relatively, as shown in
The magnetic regenerator 2m is formed by filling 6 magnetic refrigeration materials into the magnetic regenerator in a descending order according to the Curie temperatures or equivalent Curie temperatures of these magnetic refrigeration materials, and has the same operating temperature range as that of the corresponding regenerator in the gas-based regenerative refrigerator; the input signals of the sequence coupling controller 5 are the movement signals of the compression piston in the compression chamber or movement signals of the displacer; and the output signals of the sequence coupling controller 5 are relative movement signals for controlling the change of magnetic field of the permanent magnet assembly; and the flow of the working fluid in the composite refrigeration system is basically the same as that of conventional 5-stage gas-based Stirling refrigeration. This embodiment realizes the combination of 1-stage magnetic refrigeration and 5-stage gas-based regenerative refrigeration by introducing a magnetic regenerators 2n, in the last stage, the permanent magnet assembly for generating controllable and changeable field strength and the sequence coupling controller 5; the composite refrigeration system formed in such way can at least generate double refrigeration capacity at 5K with nearly no increase on energy consumption.
Embodiment 3: a refrigeration system combining magnetic refrigeration and single stage gas-based Stirling refrigeration with a refrigeration temperature of 5° C. and an ambient temperature of 30° C.
The single material of LaFeSiH based system is used as the magnetic refrigeration material, and the magnet assembly is a permanent magnet assembly for generating periodically-changing field strength, which consists of two permanent magnets arranged co-axially and rotating relatively, as shown in
The percentage of H in the LaFeSiH is changed to obtain 20 magnetic refrigeration materials with different Curie temperatures. The magnetic regenerator 2 is formed by filling these magnetic refrigeration materials in a descending order according to the Curie temperatures of these magnetic materials, and the operating temperature range of the magnetic regenerator is the same as that of the corresponding regenerator in the gas-based regenerative refrigerator; the input signals of the sequence coupling controller 5 are the movement signals of the pistons in the compression chamber and expansion chamber; the output signals of the sequence coupling controller 5 are relative movement signals for controlling change of magnetic field of the magnet assembly, wherein the input and output are coupled respectively by a simple mechanical device; and the flow of the working fluid in the composite refrigeration system is basically the same as that of the conventional single stage gas-based Stirling refrigeration. This embodiment realizes the combination of magnetic refrigeration and gas-based regenerative refrigeration by introducing the magnetic regenerator, permanent magnet assembly for generating controllable and changeable field strength and the sequence coupling controller. The refrigeration efficiency at 5° C. of the refrigeration system in this embodiment could be at least 20% higher than that of the conventional single stage gas-based Stirling refrigeration.
Embodiment 4: a refrigeration system combining magnetic refrigeration and 2-stage gas-based G-M refrigerator with a refrigeration temperature of 4.2K and an ambient temperature of 300K
8 different magnetic refrigeration materials with Curie temperatures or equivalent Curie temperatures ranging from 40K to 3K (the interval between respective Curie temperatures or equivalent Curie temperatures is about 5K), and the magnet assembly is a permanent magnet assembly for generating periodically-changing field strength, which consists of two permanent magnets arranged co-axially and rotating relatively, as shown in
The magnetic regenerator 22 is formed by filling 8 magnetic refrigeration materials into the magnetic regenerator in a descending order according to the Curie temperatures or equivalent Curie temperatures of these magnetic refrigeration materials, and has the same operating temperature range as that of the corresponding regenerator in the gas-based regenerative refrigerator; the input signals of the sequence coupling controller 5 are the movement signals of the displacer; and the output signals of the sequence coupling controller 5 are relative movement signals for controlling the change of magnetic field of the permanent magnet assembly 4 for generating controllable and changeable field strength; and the flow of the working fluid in the composite refrigeration system is basically the same as that of conventional 2-stage gas-based G-M refrigeration. This embodiment realizes the combination of magnetic refrigeration and gas-based regenerative refrigeration by introducing the magnetic regenerator, permanent magnet assembly for generating controllable and changeable field strength and the sequence coupling controller; and the composite refrigeration system formed in such way can at least generate double refrigeration capacity at 4.2K with nearly no increase on energy consumption.
The above gas-based regenerative refrigerator is described as a system including three components (namely pressure wave generator, regenerator and phase difference adjusting mechanism). Actually, the above gas-based regenerative refrigerator can also be in the following forms:
1. the pressure wave generator may be in a variety of forms, such as 1) a valveless compressor including a cylinder, piston and driving mechanism (such as Stirling type and Stirling-pulse tube type); 2) a compressor and a gas distributing valve(s) (such as G-M type, G-M-pulse tube type and SV type); 3) a thermal compressor (such as VM type and various types of thermoacoustic refrigerators);
2. the regenerator and the phase difference adjusting mechanism may be independent of each other, or combined partially or completely; although the above embodiments lists some magnetic refrigeration materials, it does not constitute any limitation to the available magnetic refrigeration materials of the present invention, the present invention does not limit and it is unnecessary to limit the type and shape of the magnetic refrigeration material of the magnetic regenerator in any way. In fact, for a specific composite refrigeration system, many materials can be selected as the magnetic refrigeration material. Those skilled in the art will appreciate and admit that different structures and combination forms of the practical refrigerators and the refrigerators of different materials shall be within the fundamental idea of the present invention, without limiting the spirit of the present invention and scopes of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010622884.6 | Dec 2010 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2011/001772 | 10/24/2011 | WO | 00 | 8/8/2013 |
