Patent Publication Number: US-10330398-B2

Title: Heat exchanger

Description:
This application claims the benefit of priority to Chinese Patent Application No. 201410068622.8 titled “HEAT EXCHANGER”, filed with the Chinese State Intellectual Property Office on Feb. 27, 2014, the entire disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present application relates to a heat exchanger, which belongs to the field of refrigeration technique, such as air conditioners and etc. 
     BACKGROUND 
     In recent decades, the air-conditioning industry has been developed rapidly, thus a heat exchanger, as one of the main components of the air conditioner, is also required to be improved to optimize the design according to the market requirements. A parallel flow heat exchanger has characteristics, such as a high cooling efficiency, a small size and a light weight, thus can meet the market requirements quite well, and it has been increasingly applied in various kinds of air conditioning systems in recent years. 
     A parallel flow heat exchanger mainly includes micro-channel flat tubes, fins and header pipes. The header pipes are provided at two ends of the micro-channel flat tubes to distribute and collect refrigerant. The corrugated or louvered fins are provided between adjacent micro-channel flat tubes to improve the heat exchange efficiency between the heat exchanger and the air. A baffle is provided inside the header pipe to divide all of the micro-channel flat tubes into a plurality of flow paths, and with reasonable distribution of flat tubes in each flow path, a better heat exchange efficiency may be realized. 
       FIGS. 1 to 4  are schematic views of a heat exchanger to be improved which is known by the inventors, a heat exchanger  100 ′ includes a first header pipe  1 ′, a second header pipe  2 ′, a third header pipe  3 ′, a fourth header pipe  4 ′, a plurality of flat tubes  5 ′, and fins  6 ′ welded between every two adjacent flat tubes  5 ′. The first header pipe  1 ′ includes a first baffle  10 ′ located inside the first header pipe  1 ′ to separate the first header pipe  1 ′ into a first space  11 ′ and a second space  12 ′. The first baffle  10 ′ is an imperforate baffle, thus the first space  11 ′ is not in direct communication with the second space  12 ′. Similarly, the third header pipe  3 ′ includes a second baffle  30 ′ located inside the third header pipe  3 ′ to separate the third header pipe  3 ′ into a third space  31 ′ and a fourth space  32 ′. The second baffle  30 ′ is also an imperforate baffle, thus the third space  31 ′ and the fourth space  32 ′ are not in direct communication with each other. 
     Reference is made to  FIGS. 3 and 4 . Arrows in the figures indicate flow directions of the refrigerant. The flow of the refrigerant in the heat exchanger  100 ′ substantially includes four flow paths. 
     In a first flow path, the refrigerant enters into the first space  11 ′ of the first header pipe  1 ′ from a refrigerant inlet, and due to the separation of the first baffle  10 ′, the refrigerant flows along corresponding flat tubes  5 ′ to the second header pipe  2 ′ in the direction of the downward arrows. 
     In a second flow path, the refrigerant entering into the second header pipe  2 ′ flows along corresponding flat tubes  5 ′ to the second space  12 ′ of the first header pipe  1 ′ in the direction of the upward arrows. 
     In a third flow path, due to the communication between the second space  12 ′ of the first header pipe  1 ′ and the third space  31 ′ of the third header pipe  3 ′, and the separation of the second baffle  30 , the refrigerant passing through the first header pipe  1 ′ flows along corresponding flat tubes  5 ′ to enter into the fourth header pipe  4 ′ in the direction of the downward arrows. 
     In a fourth flow path, the refrigerant entering into the fourth header pipe  4 ′ flows along corresponding flat tubes  5 ′ to the fourth space  32 ′ of the third header pipe  3 ′ in the direction of the upward arrows, and finally is discharged via a refrigerant outlet. 
     Referring to  FIG. 5 , with intensive research and creative efforts, the inventors have found that the first flow path to the fourth flow path have different heat exchange performances, wherein the first flow path, the second flow path, the fourth flow path have a low heat exchange performance while the third flow path have a heat exchange performance much better than that of other flow paths. 
     Therefore, an urgent technical issue to be addressed in this technical field is to improve the heat exchange performance of the heat exchanger on the whole according to heat exchange performances of different flow paths. 
     SUMMARY 
     An object of the present application is to provide a heat exchanger with a better overall heat exchange performance. 
     For realizing the above object, the following technical solutions are provided according to the present application. A heat exchanger includes a first header pipe, a second header pipe, a third header pipe, a fourth header pipe and a plurality of flat tubes, one part of the flat tubes connect the first header pipe to the second header pipe, another part of the flat tubes connect the third header pipe to the fourth header pipe, the first header pipe includes a first space and a second space, wherein a flow path, that the refrigerant flows from the first space of the first header pipe to the second header pipe along corresponding flat tubes, is defined as a first flow path; a flow path, that the refrigerant flows from the second header pipe to the second space of the first header pipe along corresponding flat tubes, is defined as a second flow path; and a flow path, that the refrigerant passing through the second space flows from the third header pipe to the fourth header pipe along corresponding flat tubes, is defined as a third flow path; and wherein the heat exchanger also includes a communicating passage for communicating the first space with the second space, and when the refrigerant flows from the first space of the first header pipe to the second header pipe along the flat tubes, a part of the refrigerant passes through the communicating passage to directly enter into the second space of the first header pipe. 
     For realizing the above object, a heat exchanger is further provided according to the present application, which includes a first header pipe, a second header pipe, a third header pipe, a fourth header pipe and a plurality of flat tubes, one part of the flat tubes connect the first header pipe to the second header pipe, another part of the flat tubes connect the third header pipe to the fourth header pipe, the first header pipe includes a first space and a second space, the first space is in communication with the second header pipe through corresponding flat tubes, the second header pipe is in communication with the second space of the first header pipe through corresponding flat tubes, and the second space is in communication with the third header pipe, and the heat exchanger also includes a communicating passage for communicating the first space with the second space. 
     Compared with the technique to be improved, in the first flow path of the present application, a small part of the refrigerant directly enters into the second space of the first header pipe through the communicating passage, skipping the first flow path and the second flow path, thus the flow quantity of the refrigerant in the first flow path and the second flow path is decreased and the flow resistance is greatly decreased, thus the overall flow resistance of the heat exchanger of the present application may be reduced to some extent. Besides, the flow quantity of the refrigerant in the third flow path is constant, however fluid state parameters may change, and the change of the fluid state parameters may greatly improve the heat exchange capacity of the third flow path, thereby improving the heat exchange performance of the heat exchanger on the whole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a heat exchanger to be improved which is known to the inventors. 
         FIG. 2  is a perspective view of the heat exchanger in  FIG. 1  seen from another angle. 
         FIG. 3  is a schematic view showing a first flow path and a second flow path of the heat exchanger in  FIG. 1 . 
         FIG. 4  is schematic view showing a third flow path and a fourth flow path of the heat exchanger in  FIG. 1 . 
         FIG. 5  is a schematic view showing the analysis of heat exchange capabilities of the first flow path to the fourth flow path of the heat exchanger in  FIG. 1 . 
         FIG. 6  is a perspective schematic view of a heat exchanger according to the present application. 
         FIG. 7  is a perspective schematic view showing a first baffle arranged inside a first header pipe in  FIG. 6 . 
         FIG. 8  is a perspective schematic view showing a second baffle arranged inside a third header pipe in  FIG. 6 . 
         FIG. 9  is a schematic view showing a first flow path and a second flow path of the heat exchanger according to the present application. 
         FIG. 10  is a schematic view showing a third flow path and a fourth flow path of the heat exchanger according to the present application. 
         FIG. 11  is a comparison diagram of the heat exchange efficiencies of the heat exchanger according to the present application and the heat exchanger in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 6 to 10 , a heat exchanger  100  is provided according to the present application, and may be applied in air conditioners, household appliances and other systems requiring the heat exchanger. In an embodiment shown in the figures of the present application, the heat exchanger  100  is a laminated micro-channel heat exchanger. The heat exchanger  100  includes a first header pipe  1 , a second header pipe  2 , a third header pipe  3 , a fourth header pipe  4 , a plurality of flat tubes  5 , and fins  6  welded between every two adjacent flat tubes  5 . One part of the flat tubes  5  connect the first header pipe  1  to the second header pipe  2 , and another part of the flat tubes  5  connect the third header pipe  3  to the header pipe  4 . In an embodiment shown in figures of the present application, each of the flat tubes  5  is a micro-channel flat tube and has two ends respectively inserted into a respective header pipe. 
     Referring to  FIGS. 6 and 9 , the first header pipe  1  includes a first baffle  10  located inside the first header pipe  1  to substantially separate the first header pipe  1  into a first space  11  and a second space  12 . Referring to  FIG. 7 , the first baffle  10  is provided with a plurality of through holes  101 , and these through holes  101  are used as a communicating passage for communicating the first space  11  with the second space  12 . 
     Of course, in other embodiments of the present application, a communicating pipe may also be provided. The communicating pipe is provided with a flow passage pipeline, and the flow passage is used as a communicating passage for communicating the first space  11  with the second space  12 . In this case, the first baffle  10  in  FIG. 9  may be replaced with an imperforate baffle. As shown in  FIGS. 12-15 , the communicating pipes  70 ,  71  are inserted in a baffle  70 , and the flow passages formed in the communicating pipes  70 ,  71  are used as communicating passages for communicating the first space  11  with the second space  12 . As shown in  FIG. 14 , the communicating pipe  71  may be a pipe with two ends extending into the first space and the second space respectively, and as shown in  FIG. 15 , the communicating pipe  72  may be a pipe with two ends extending into the first space  11  and the second space  12  respectively, and one of the two ends has a flange abutting against an end surface of the baffle  70 . 
     In embodiments shown in the figures of the present application, the second header pipe  2  and the fourth header pipe  4  are both a straight-through tube, and are both not provided with any baffle. Of course, a perforated baffle or an imperforate baffle may also be provided inside the second header pipe  2  and the fourth header pipe  4  according to different flow paths. 
     Referring to  FIGS. 6, 8 and 10 , the third header pipe  3  includes a second baffle  30  located inside the third header pipe  3  to separate the third header pipe  3  into a third space  31  and a fourth space  32 . The second baffle  30  is an imperforate baffle without through holes  101 , thus the third space  31  and the fourth space  32  are not in direct communication with each other. Besides, the heat exchanger  100  also includes a refrigerant inlet  13  in communication with the first space  11  and a refrigerant outlet  14  in communication with the fourth space  32 . 
     Referring to  FIG. 6 , in an embodiment shown in the figure of the present application, the first header pipe  1  and the third header pipe  3  are arranged in parallel and adjacent to each other, and the second header pipe  2  and the fourth header pipe  4  are arranged in parallel and adjacent to each other. On the whole, the first header pipe  1  and the third header pipe  3  are located at one side of the heat exchanger  100  (which is an upper side of the figure in this embodiment), and the second header pipe  2  and the fourth header pipe  4  are located at the other side of the heat exchanger  100  (which is a lower side of the figure in this embodiment). 
     Referring to  FIGS. 9 and 10 , arrows in the figures indicate flow directions of the refrigerant. In the embodiment shown in figures of the present application, flow of the refrigerant in the heat exchanger  100  substantially includes four flow paths. 
     In a first flow path, the refrigerant enters into the first space  11  of the first header pipe  1  from the refrigerant inlet  13 , and due to the separation of the first baffle  10 , most of the refrigerant flows along corresponding flat tubes  5  to the second header pipe  2  in the direction indicated by the downward arrows. 
     It should be noted that, in the embodiment shown in the figures of the present application, the first baffle  10  is provided with through holes  101  functioning as the communicating passage, thus a small part of refrigerant passes through the communicating passage in the direction indicated by the rightward arrow and directly enters into the second space  12  of the first header pipe  1 . Of course, in the embodiments using the communicating pipe, a small part of refrigerant may directly enter into the second space  12  along the communicating pipe. 
     In a second flow path, the refrigerant entering into the second header pipe  2  flows along corresponding flat tubes  5  to the second space  12  of the first header pipe  1  in the direction indicated by the upward arrows. 
     In a third flow path, due to the communication between the second space  12  of the first header pipe  1  and the third space  31  of the third header pipe  3 , and the separation of the second baffle  30 , the refrigerant passing through the first header pipe  1  flows along corresponding flat tubes  5  and enters into the fourth header pipe  4  in the direction indicated by the downward arrows. 
     In a fourth flow path, the refrigerant entering into the fourth header pipe  4  flows along corresponding flat tubes  5  to the fourth space  32  of the third header pipe  3  in the direction indicated by the upward arrows, and finally is discharged via the refrigerant outlet  14 . 
     Of course, in other embodiments, the second baffle  30  may not be provided, and the refrigerant outlet  14  is provided on the fourth header pipe  4 . In this case, in the third flow path, the refrigerant flows from the third header pipe  3  to the fourth header pipe  4  and is discharged via the refrigerant outlet  14 , and there is no fourth flow path. 
     It can be appreciated that, in the first flow path of the present application, a small part of the refrigerant directly enters into the second space  12  of the first header pipe  1  through the communicating passage, skipping the first flow path and the second flow path, thus the flow quantity of the refrigerant in the first flow path and the second flow path is decreased and the flow resistance is greatly decreased. However, with a lot of research, experiments and creative efforts, the applicant has found that heat transfer capacities of these two flow paths are mainly limited by air state parameters, therefore the decrease of the flow quantity of the refrigerant did not have a great impact on the heat exchange performance. 
     Besides, the flow quantity of the refrigerant in the third flow path and the fourth flow path is constant, however the fluid state parameters may change, and the flow resistance is increased slightly as the dryness or temperature decreases. With a lot of research, experiments and creative efforts, the applicant has found that heat exchange performance of the third flow path is mainly limited by relevant fluid state parameters of the refrigerant, thus the change of the fluid state parameters may significantly increase the heat exchange capacity of the third flow path as well as the heat exchange capacity of the fourth flow path. It should be noted that, in an embodiment without the fourth flow path, it is only required to consider the improvement of the heat exchange capacity of the third flow path, and there is no need to consider the heat exchange capacity of the fourth flow path. 
     In conclusion, in the present application, by providing the communicating passage, a small part of refrigerant skips the first flow path and the second flow path, and although it appears that the heat exchange performance may be reduced since this part of refrigerant did not participated in heat exchange. Indeed, the experiments show that the heat exchange performance may be reduced slightly, however since the heat exchange capacities of these two flow paths are mainly limited by the air state parameters, the decrease of the flow quantity of the refrigerant did not have a great impact on the heat exchange performance. However, at the same time, since the small part of the refrigerant skips the first flow path and the second flow path, the flow quantity of the refrigerant in the first flow path and the second flow path is decreased, and the flow resistance is greatly reduced. Besides, the above change may change the fluid state parameters of the refrigerant in the third flow path and the fourth flow path, and such change may greatly increase the heat exchange capacity of the third flow path and may also increase the heat exchange capacity of the fourth flow path. That is, the increment of the heat exchange performance in the third flow path and the fourth flow path is greater than the loss of the heat exchange performance in the first flow path and the second flow path, therefore, on the whole, with the design of the present application, the overall heat exchange performance of the heat exchanger  100  can be improved (which can refer to the comparison diagram shown in  FIG. 11 ). Besides, the decrease of the refrigerant in the first flow path and the second flow path is greater than the increase of the refrigerant in the third flow path and the fourth flow path, therefore, the overall flow resistance of the heat exchanger  100  may be decreased to some extent. The heat exchanger can be used as an evaporator in a system or as a cooling device in a system without an evaporator. 
     In the conventional technology, the heat exchange performance is simply equated with the refrigerant participating in the heat exchange, which is not the most scientific view. The present application overcomes this technique prejudice in the conventional technology, and as shown by the results, even though a part of the refrigerant has not participated in the heat exchange of a certain flow path, the heat exchange performance of the heat exchanger can also be improved on the whole. 
     It should be noted that, the above embodiments are only intended for describing the present application, and should not be interpreted as limitation to the technical solutions of the present application. Although the present application is described in detail in conjunction with the above embodiments, it should be understood by the person skilled in the art that, modifications or equivalent substitutions may also be made to the present application by the person skilled in the art; and any technical solutions and improvements thereof without departing from the spirit and scope of the present application fall into the scope of the present application defined by the claims.