Patent Publication Number: US-2021172398-A1

Title: Regenerator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     All related applications are incorporated by reference. The present application is based on, and claims priority from, Taiwan Application Serial Number 108144205, filed on Dec. 4, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The technical field relates to a regenerator, in particular to a high-performance regenerator for Stirling cooler. 
     BACKGROUND 
     Stirling coolers adopts reverse Stirling cycle, which is an enclosed gas cycle. A motor in a Stirling cooler drives a piston to compress and inflate the gas. Besides, a displacer is disposed between the hot end and the cold end of the Stirling cooler to make the gas cyclically flows; in addition, a regenerator disposed inside the Stirling cooler can form a high-temperature end and a low-temperature end. Therefore, the regenerator is an important element of Stirling coolers. The purpose of the regenerator is to store and reuse most of the thermal energy provided by the heat source in order to save energy. The temperature of the gas cannot gradually increase or decrease on a gradient basis without the regenerator, so the Stirling cooler should waste more energy to achieve the desired performance. 
     However, the performance of the currently available regenerators cannot be further improved due to the limits of the structures thereof, so the performance of Stirling coolers also cannot be further enhanced. 
     Therefore, it has become an important issue to provide a regenerator capable of improving the shortcomings of the currently available regenerators. 
     SUMMARY 
     Therefore, it is a primary objective of the present invention to provide a regenerator so as to solve the shortcomings of the currently available regenerators. 
     An embodiment of the disclosure relates to a regenerator, which includes a hollow pipe body, a first mesh portion, a second mesh portion and a third mesh portion. The first mesh portion is disposed inside the hollow pipe body and at the rear portion of the hollow pipe body. The second mesh portion is disposed inside and at the central portion of the hollow pipe body, and connected to the first mesh portion. The third mesh portion is disposed inside and at the front portion of the hollow pipe body, and connected to the second mesh portion. The mesh number of the first mesh portion, the mesh number of the second mesh portion and the mesh number of the third mesh portion are increased from the rear portion to the front portion of the hollow pipe body. 
     In one embodiment, there is a highest common factor M 1  of the mesh number of the first mesh portion, the mesh number of the second mesh portion and the mesh number of the third mesh portion. 
     In one embodiment, the mesh number of the first mesh portion, the mesh number of the second mesh portion and the mesh number of the third mesh portion are increased from the rear portion to the front portion of the hollow pipe body on a basis of an arithmetic sequence E 1 , wherein the common difference of the arithmetic sequence E 1  is the highest common factor M 1 . 
     In one embodiment, the difference between the second mesh portion and the mesh number of the first mesh portion is the highest common factor M 1 , and the difference between the mesh number of the third mesh portion and the mesh number of the second mesh portion is two times the highest common factor M 1 . 
     In one embodiment, the difference between the second mesh portion and the mesh number of the first mesh portion is the is two times the highest common factor M 1 , and the difference between the mesh number of the third mesh portion and the mesh number of the second mesh portion is the highest common factor M 1 . 
     In one embodiment, the length of the first mesh portion, the length of the second mesh portion and the length of the third mesh portion are equal. 
     In one embodiment, there is a highest common factor M 2  of the length of the first mesh portion, the length of the second mesh portion and the length of the third mesh portion. 
     In one embodiment, the length of the first mesh portion, the length of the second mesh portion and the length of the third mesh portion are decreased on a basis of an arithmetic sequence E 2 . 
     In one embodiment, the common difference of the arithmetic sequence E 2  is the highest common factor M 2 . 
     In one embodiment, the length of the first mesh portion is equal to the length of the second mesh portion, and the length of the third mesh portion is the highest common factor M 2 . 
     Another embodiment of the disclosure relates to a regenerator, which includes a hollow pipe body, a first mesh portion, a second mesh portion, a third mesh portion and a fourth mesh portion. The first mesh portion is disposed inside the hollow pipe body and at the rear portion of the hollow pipe body. The second mesh portion is disposed inside and at the central portion of the hollow pipe body, and connected to the first mesh portion. The third mesh portion is disposed inside and at the central portion of the hollow pipe body, and connected to the second mesh portion. The fourth mesh portion is disposed inside and at the front portion of the hollow pipe body, and connected to the third mesh portion. The mesh number of the first mesh portion, the mesh number of the second mesh portion, the mesh number of the third mesh portion and the mesh number of the fourth mesh portion are increased from the rear portion to the front portion of the hollow pipe body. 
     In one embodiment, there is a highest common factor M 3  of the mesh number of the first mesh portion, the mesh number of the second mesh portion, the mesh number of the third mesh portion and the mesh number of the fourth mesh portion. 
     In one embodiment, the mesh number of the first mesh portion, the mesh number of the second mesh portion, the mesh number of the third mesh portion and the mesh number of the fourth mesh portion are increased from the rear portion to the front portion of the hollow pipe body on a basis of an arithmetic sequence E 3 ; the common difference of the arithmetic sequence E 3  is the highest common factor M 3 . 
     In one embodiment, the difference between the second mesh portion and the mesh number of the first mesh portion is the highest common factor M 3 , the difference between the mesh number of the third mesh portion and the mesh number of the second mesh portion is the highest common factor M 3 , and the difference between the mesh number of the fourth mesh portion and the mesh number of the third mesh portion is two times the highest common factor M 3 . 
     In one embodiment, the difference between the second mesh portion and the mesh number of the first mesh portion is the highest common factor M 3 , the difference between the mesh number of the third mesh portion and the mesh number of the second mesh portion is two times the highest common factor M 3 , and the difference between the mesh number of the fourth mesh portion and the mesh number of the third mesh portion is the highest common factor M 3 . 
     In one embodiment, the length of the first mesh portion, the length of the second mesh portion, the length of the third mesh portion and the length of the fourth mesh portion are equal. 
     In one embodiment, wherein there is a highest common factor M 4  of the length of the first mesh portion, the length of the second mesh portion, the length of the third mesh portion and the length of the fourth mesh portion. 
     In one embodiment, the difference between the length of the second mesh portion and the length of the first mesh portion is the highest common factor M 4 , and the length of the second mesh portion, the length of the third mesh portion and the length of the fourth mesh portion are equal. 
     In one embodiment, the length of the second mesh portion and the length of the first mesh portion are equal, the difference between the length of the third mesh portion and the length of the second mesh portion is the highest common factor M 4 , and the difference between the length of the fourth mesh portion and the length of the third mesh portion is the highest common factor M 4 . 
     In one embodiment, the difference between the length of the second mesh portion and the length of the first mesh portion is two times the highest common factor M 4 , the length of the third mesh portion and the length of the second mesh portion are equal, and the difference between the length of the fourth mesh portion and the length of the third mesh portion is the highest common factor M 4 . 
     As described above, the regenerator in accordance with the embodiments of the disclosure has the following advantages: 
     (1) In one embodiment of the disclosure, the regenerator includes multiple mesh portions and these mesh portions have a special gradient mesh structure, which can significantly improve the coefficient of performance (COP) and the maximal flow velocity of the regenerator, so the performance of the regenerator can be enhanced. 
     (2) In one embodiment of the disclosure, the regenerator includes multiple mesh portions and the lengths of the mesh portions are specially designed, which can further improve the coefficient of performance and the maximal flow velocity of the regenerator, so the performance of the regenerator can be further enhanced. 
     (3) In one embodiment of the disclosure, the coefficient of performance and the maximal flow velocity of the regenerator can be dramatically improved, so the performance of the Stirling cooler adopting the regenerator can be also effectively improved. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the disclosure and wherein: 
         FIG. 1  is a stereoscopic view of a regenerator in accordance with a first embodiment of the disclosure. 
         FIG. 2  is a sectional view of the regenerator in accordance with the first embodiment of the disclosure. 
         FIG. 3  is a stereoscopic view of a regenerator in accordance with a second embodiment of the disclosure. 
         FIG. 4  is a sectional view of the regenerator in accordance with the second embodiment of the disclosure. 
         FIG. 5  is a simulation result of maximal flow velocity of a regenerator in accordance with a third embodiment of the disclosure. 
         FIG. 6  is a simulation result of coefficient of performance of the regenerator in accordance with the third embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     Please refer to  FIG. 1  and  FIG. 2 , which are a stereoscopic view and a sectional view of a regenerator in accordance with a first embodiment of the disclosure respectively. As shown in  FIG. 1 , the regenerator  1  includes a hollow pipe body  11 , a first mesh portion  12 - 1 , a second mesh portion  12 - 2  and a third mesh portion  12 - 3 . In the embodiment, the inside diameter of the hollow pipe body  11  is 5 mm and the outside diameter of the hollow pipe body  11  is 6 mm. In another embodiment, the inside diameter and the outside diameter of the hollow pipe body  11  can be designed according to actual requirements. 
     As shown in  FIG. 2 , the first mesh portion  12 - 1  may be disposed inside the hollow pipe body  11  and at the rear portion of the hollow pipe body  11 . 
     The second mesh portion  12 - 2  may be disposed inside the hollow pipe body  11  and at the central portion of the hollow pipe body  11  and connected to the first mesh portion  12 - 1 . 
     The third mesh portion  12 - 3  may be disposed inside the hollow pipe body  11  and at the front portion of the hollow pipe body  11  and connected to the second mesh portion  12 - 2 . 
     More specifically, the mesh number of the first mesh portion  12 - 1 , the mesh number of the second mesh portion  12 - 2  and the mesh number of the third mesh portion  12 - 3  are increased from the rear portion of the hollow pipe body  11  to the front portion thereof. Besides, there is a highest common factor M 1  of the mesh number of the first mesh portion  12 - 1 , the mesh number of the second mesh portion  12 - 2  and the mesh number of the third mesh portion  12 - 3 . In the embodiment, the highest common factor M 1  is 50. In another embodiment, the highest common factor M 1  may be other values (e.g. 25, 100 . . . ). 
     In the embodiment, the mesh number of the first mesh portion  12 - 1 , the mesh number of the second mesh portion  12 - 2  and the mesh number of the third mesh portion  12 - 3  are increased from the rear portion of the hollow pipe body  11  to the front portion of the hollow pipe body  11  on a basis of an arithmetic sequence E 1 ; the common difference of the arithmetic sequence E 1  is the highest common factor M 1 . For example, the mesh number of the first mesh portion  12 - 1  is 200; the mesh number of the second mesh portion  12 - 2  is 250; the mesh number of the third mesh portion  12 - 3  is 300 (the highest common factor M 1  is 50). 
     In another embodiment, the difference between the second mesh portion  12 - 2  and the mesh number of the first mesh portion  12 - 1  is the highest common factor M 1 . The difference between the mesh number of the third mesh portion  12 - 3  and the mesh number of the second mesh portion  12 - 2  is two times the highest common factor M 1 . For instance, the mesh number of the first mesh portion  12 - 1  is 250; the mesh number of the second mesh portion  12 - 2  is 300; the mesh number of the third mesh portion  12 - 3  is 400 (the highest common factor M 1  is 50). 
     In still another embodiment, the difference between the second mesh portion  12 - 2  and the mesh number of the first mesh portion  12 - 1  is two times the highest common factor M 1 . The difference between the mesh number of the third mesh portion  12 - 3  and the mesh number of the second mesh portion  12 - 2  is the highest common factor M 1 . For instance, the mesh number of the first mesh portion  12 - 1  is 300; the mesh number of the second mesh portion  12 - 2  is 400; the mesh number of the third mesh portion  12 - 3  is 450 (the highest common factor M 1  is 50). 
     There is a highest common factor M 2  of the length of the first mesh portion  12 - 1 , the length of the second mesh portion  12 - 2  and the length of the third mesh portion  12 - 3 . In the embodiment, the highest common factor M 2  is 5 mm. In another embodiment, the highest common factor M 2  may be other values (e.g. 10 mm, 15 mm . . . ). 
     In the embodiment, the length of the first mesh portion  12 - 1 , the length of the second mesh portion  12 - 2  and the length of the third mesh portion  12 - 3  are equal. For instance, the length of the first mesh portion  12 - 1 , the length of the second mesh portion  12 - 2  and the length of the third mesh portion  12 - 3  are 15 mm (the highest common factor M 2  is 5 mm). 
     In another embodiment, the length of the first mesh portion  12 - 1 , the length of the second mesh portion  12 - 2  and the length of the third mesh portion  12 - 3  are decreased on a basis of an arithmetic sequence E 2 ; the common difference of the arithmetic sequence E 2  is the highest common factor M 2 . For instance, the length of the first mesh portion  12 - 1  is 20 mm; the length of the second mesh portion  12 - 2  is 15 mm; the length of the third mesh portion  12 - 3  is 10 mm (the highest common factor M 2  is 5 mm). 
     In still another embodiment, the length of the first mesh portion  12 - 1  is equal to the length of the second mesh portion  12 - 2  and the length of the third mesh portion  12 - 3  is the highest common factor M 2 . For example, the length of the first mesh portion  12 - 1  and the length of the second mesh portion  12 - 2  are 20 mm; the length of the third mesh portion  12 - 3  is 5 mm (the highest common factor M 2  is 5 mm). 
     As described above, the regenerator  1  of the embodiment has multiple mesh portions (the first mesh portion  12 - 1 , the second mesh portion  12 - 2  and the third mesh portion  12 - 3 ), and the mesh portions have a special gradient mesh structure; besides, the lengths of the mesh portions are also specially designed. The above special structure designs can considerably increase the coefficient of performance (COP) and the maximal flow velocity of the regenerator  1 , so the performance of the regenerator  1  can be further improved. 
     The embodiment just exemplifies the disclosure and is not intended to limit the scope of the disclosure. Any equivalent modification and variation according to the spirit of the disclosure is to be also included within the scope of the following claims and their equivalents. 
     It is worthy to point out that the performance of the currently available regenerators cannot be further improved due to the limits of the structures thereof, so the performance of Stirling coolers also cannot be further enhanced. On the contrary, according to one embodiment of the disclosure, the regenerator includes multiple mesh portions and these mesh portions have a special gradient mesh structure and the lengths of the mesh portions are also specially designed, which can significantly improve the coefficient of performance (COP) and the maximal flow velocity of the regenerator, so the performance of the regenerator can be enhanced. 
     Besides, according to one embodiment of the disclosure, the coefficient of performance and the maximal flow velocity of the regenerator can be dramatically improved, so the performance of the Stirling cooler adopting the regenerator can be also effectively improved. Therefore, the regenerator in accordance with the disclosure can definitely achieve great technical effects. 
     Please refer to  FIG. 3  and  FIG. 4 , which are a stereoscopic view and a sectional view of a regenerator in accordance with a second embodiment of the disclosure respectively. As shown in  FIG. 3 , the regenerator  2  includes a hollow pipe body  21 , a first mesh portion  22 - 1 , a second mesh portion  22 - 2 , a third mesh portion  22 - 3  and a fourth mesh portion  22 - 4 . In the embodiment, the inside diameter of the hollow pipe body  21  is 5 mm and the outside diameter of the hollow pipe body  21  is 6 mm. 
     As shown in  FIG. 4 , the first mesh portion  22 - 1  may be disposed inside the hollow pipe body  21  and at the rear portion of the hollow pipe body  21 . 
     The second mesh portion  22 - 2  may be disposed inside the hollow pipe body  21  and at the central portion of the hollow pipe body  21  and connected to the first mesh portion  22 - 1 . 
     The third mesh portion  22 - 3  may be disposed inside the hollow pipe body  21  and at the central portion of the hollow pipe body  21  and connected to the second mesh portion  22 - 2 . 
     The fourth mesh portion  22 - 4  may be disposed inside the hollow pipe body  21  and at the front portion of the hollow pipe body  21  and connected to the third mesh portion  22 - 3 . 
     More specifically, the mesh number of the first mesh portion  22 - 1 , the mesh number of the second mesh portion  22 - 2 , the mesh number of the third mesh portion  22 - 3  and the mesh number of the fourth mesh portion  22 - 4  are increased from the rear portion of the hollow pipe body  21  to the front portion thereof. Besides, there is a highest common factor M 3  of the mesh number of the first mesh portion  22 - 1 , the mesh number of the second mesh portion  22 - 2 , the mesh number of the third mesh portion  22 - 3  and the mesh number of the fourth mesh portion  22 - 4 . In the embodiment, the highest common factor M 3  is 50. In another embodiment, the highest common factor M 1  may be other values (e.g. 25, 100 . . . ). 
     In the embodiment, the mesh number of the first mesh portion  22 - 1 , the mesh number of the second mesh portion  22 - 2 , the mesh number of the third mesh portion  22 - 3  and the mesh number of the fourth mesh portion  22 - 4  are increased from the rear portion of the hollow pipe body  21  to the front portion of the hollow pipe body  21  on a basis of an arithmetic sequence E 2 ; the common difference of the arithmetic sequence E 2  is the highest common factor M 3 . For example, the mesh number of the first mesh portion  22 - 1  is 200; the mesh number of the second mesh portion  22 - 2  is 250; the mesh number of the third mesh portion  22 - 3  is 350; the mesh number of the fourth mesh portion  22 - 4  is 400; the highest common factor M 3  is 50. 
     In another embodiment, the difference between the second mesh portion  22 - 2  and the mesh number of the first mesh portion  22 - 1  is the highest common factor M 3 . The difference between the mesh number of the third mesh portion  22 - 3  and the mesh number of the second mesh portion  22 - 2  is the highest common factor M 3 . The difference between the mesh number of the fourth mesh portion  22 - 4  and the mesh number of the third mesh portion  22 - 3  is two times the highest common factor M 3 . For instance, the mesh number of the first mesh portion  22 - 1  is 250; the mesh number of the second mesh portion  22 - 2  is 250; the mesh number of the third mesh portion  22 - 3  is 300; the mesh number of the fourth mesh portion  22 - 4  is 400 (the highest common factor M 1  is 50). 
     In still another embodiment, the difference between the second mesh portion  22 - 2  and the mesh number of the first mesh portion  22 - 1  is the highest common factor M 3 . The difference between the mesh number of the third mesh portion  22 - 3  and the mesh number of the second mesh portion  22 - 2  is two times the highest common factor M 3 . The difference between the mesh number of the fourth mesh portion  22 - 4  and the mesh number of the third mesh portion  22 - 3  is the highest common factor M 3 . For instance, the mesh number of the first mesh portion  22 - 1  is 250; the mesh number of the second mesh portion  22 - 2  is 300; the mesh number of the third mesh portion  22 - 3  is 400; the mesh number of the fourth mesh portion  22 - 4  is 450 (the highest common factor M 3  is 50). 
     There is a highest common factor M 4  of the length of the first mesh portion  22 - 1 , the length of the second mesh portion  22 - 2 , the length of the third mesh portion  22 - 3  and the length of the fourth mesh portion  22 - 4 . In the embodiment, the highest common factor M 4  is 5 mm. In another embodiment, the highest common factor M 4  may be other values (e.g. 10 mm, 15 mm . . . ). 
     In the embodiment, the difference between the length of the second mesh portion  22 - 2  and the length of the first mesh portion  22 - 1  is the highest common factor M 4 , and the length of the second mesh portion  22 - 2 , the length of the third mesh portion  22 - 3  and the length of the fourth mesh portion  22 - 4  are equal. For instance, the length of the first mesh portion  22 - 1  is 15 mm; the length of the second mesh portion  22 - 2 , the length of the third mesh portion  22 - 3  and the length of the fourth mesh portion  22 - 4  are 10 mm (the highest common factor M 4  is 5 mm). 
     In another embodiment, the length of the second mesh portion  22 - 2  is equal to the length of the first mesh portion  22 - 1 . The difference between the length of the third mesh portion  22 - 3  and the length of the second mesh portion  22 - 2  is the highest common factor M 4 . The difference between the length of the fourth mesh portion  22 - 4  and the length of the third mesh portion  22 - 3  is the highest common factor M 4 . For example, the length of the first mesh portion  22 - 1  and the length of the second mesh portion  22 - 2  are 15 mm; the length of the third mesh portion  22 - 3  is 10 mm; the length of the fourth mesh portion  22 - 4  is 5 mm (the highest common factor M 4  is 5 mm). 
     In still another embodiment, the difference between the length of the second mesh portion  22 - 2  and the length of the first mesh portion  22 - 1  is two times the highest common factor M 4 . The length of the third mesh portion  22 - 3  is equal to the length of the second mesh portion  22 - 2 . The difference between the length of the fourth mesh portion  22 - 4  and the length of the third mesh portion  22 - 3  is the highest common factor M 4 . For example, the length of the first mesh portion  22 - 1  is 20 mm; the length of the second mesh portion  22 - 2  and the length of the third mesh portion  22 - 3  are 10 mm; the length of the fourth mesh portion  22 - 4  is 5 mm (the highest common factor M 4  is 5 mm). 
     In still another embodiment, the mesh number of the first mesh portion  22 - 1 , the mesh number of the second mesh portion  22 - 2 , the mesh number of the third mesh portion  22 - 3  and the mesh number of the fourth mesh portion  22 - 4  may be equal. 
     As described above, the regenerator  2  of the embodiment also has multiple mesh portions (the first mesh portion  22 - 1 , the second mesh portion  22 - 2 , the third mesh portion  22 - 3  and the fourth mesh portion  22 - 4 ), and the mesh portions have a special gradient mesh structure; besides, the lengths of the mesh portions are also specially designed. The above special structure designs can considerably increase the coefficient of performance (COP) and the maximal flow velocity of the regenerator  1 , so the performance of the regenerator  1  can be further improved. 
     In still another embodiment, the average size of the meshes in the central part of the first mesh portion  22 - 1  is larger than the average size of the meshes in the peripheral part of the first mesh portion  22 - 1 . For example, the average size of the meshes in the peripheral part of the first mesh portion  22 - 1  is ¾ (or ⅘ ⅚, 6/7) of the average size of the meshes in the central part of the first mesh portion  22 - 1 . The central part is a cylinder at the middle of the first mesh portion  22 - 1  and the circle center of the central part is the center of the first mesh portion  22 - 1 . The peripheral part is a ring-shaped part around the central part; besides, the radius of the central part is a half of the radius of the first mesh portion  22 - 1 . The second mesh portion  22 - 2 , the third mesh portion  22 - 3  and the fourth mesh portion  22 - 4  also have the above structure. Which can effectively improve the performance of the regenerator  2 . 
     The embodiment just exemplifies the disclosure and is not intended to limit the scope of the disclosure. Any equivalent modification and variation according to the spirit of the disclosure is to be also included within the scope of the following claims and their equivalents. 
     Please refer to  FIG. 5  and  FIG. 6 , which are a simulation result of maximal flow velocity and a simulation result of coefficient of performance of a regenerator in accordance with a third embodiment of the disclosure. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Number of 
                   
                   
               
               
                 regener- 
                   
                 Mesh numbers of mesh 
               
               
                 ator 
                 Lengths of mesh portions 
                 portions 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 15 mm, 15 mm, 15 mm 
                 #200, #250, #300 
               
               
                 2 
                 15 mm, 15 mm, 15 mm 
                 #250, #300, #400 
               
               
                 3 
                 15 mm, 15 mm, 15 mm 
                 #300, #400, #450 
               
               
                 4 
                 20 mm, 15 mm, 10 mm 
                 #200, #250, #300 
               
               
                 5 
                 20 mm, 15 mm, 10 mm 
                 #250, #300, #400 
               
               
                 6 
                 20 mm, 15 mm, 10 mm 
                 #300, #400, #450 
               
               
                 7 
                 20 mm, 20 mm, 5 mm  
                 #200, #250, #300 
               
               
                 8 
                 20 mm, 20 mm, 5 mm  
                 #250, #300, #400 
               
               
                 9 
                 20 mm, 20 mm, 5 mm  
                 #300, #400, #450 
               
               
                 10 
                  15 mm, 10 mm, 10 mm, 10 mm 
                 #200, #250, #300, #400 
               
               
                 11 
                  15 mm, 10 mm, 10 mm, 10 mm 
                 #250, #300, #400, #450 
               
               
                 12 
                 15 mm, 15 mm, 10 mm, 5 mm 
                 #200, #250, #300, #400 
               
               
                 13 
                 15 mm, 15 mm, 10 mm, 5 mm 
                 #250, #300, #400, #450 
               
               
                 14 
                 20 mm, 10 mm, 10 mm, 5 mm 
                 #200, #250, #300, #400 
               
               
                 15 
                 20 mm, 10 mm, 10 mm, 5 mm 
                 #250, #300, #400, #450 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 5 , the maximal flow velocity of each regenerator can be greater than 7 m/s, so the flow velocities of these regenerators can conform to actual requirements. 
     As shown in  FIG. 6 , the coefficient of performance of each regenerator can be greater than 0.07, so the performance of these regenerators can be obviously improved, in particular to the regenerators of No. 4-No. 15. 
     To sum up, according to one embodiment of the disclosure, the regenerator includes multiple mesh portions and these mesh portions have a special gradient mesh structure, which can significantly improve the coefficient of performance (COP) and the maximal flow velocity of the regenerator, so the performance of the regenerator can be enhanced. 
     Besides, according to one embodiment of the disclosure, the regenerator includes multiple mesh portions and the lengths of the mesh portions are specially designed, which can further improve the coefficient of performance and the maximal flow velocity of the regenerator, so the performance of the regenerator can be further enhanced. 
     Moreover, according to one embodiment of the disclosure, the coefficient of performance and the maximal flow velocity of the regenerator can be dramatically improved, so the performance of the Stirling cooler adopting the regenerator can be also effectively improved. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.