Patent Publication Number: US-10317147-B2

Title: Tank and heat exchanger

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase Application under 35 U.S.C. 371 of International Application No. PCT/JP2016/001579 filed on Mar. 18, 2016 and published in Japanese as WO 2016/152127 A1 on Sep. 29, 2016. This application is based on and claims the benefit of priority from Japanese Patent Application No. 2015-057470 filed on Mar. 20, 2015 and Japanese Patent Application No. 2016-051175 filed on Mar. 15, 2016, The entire disclosures of all of the above applications are incorporated herein by reference. 
     Technical Field 
     The present disclosure relates to a tank in which a fluid flows and a heat exchanger having the tank. 
     Background Art 
     Conventionally, a refrigeration cycle using carbon dioxide as refrigerant is known. The refrigeration cycle has a refrigerant radiator (i.e., a heat exchanger for radiating heat). Since a pressure in the refrigeration cycle becomes high, components configuring the refrigerant radiator are required to have pressure resistance. Especially, a tank is required to have higher pressure resistance since the tank has the largest passage sectional area in the refrigerant radiator, as described in Patent Literature 1. 
     Then, a heat exchanger having a tank that is configured by three members of a tank body, a plate, and an intermediate plate is disclosed (e.g., refer to Patent Literature 2). The refrigerant flows in the tank body. The plate is connected with tubes. The intermediate plate has a plate shape and is arranged between the tank body and the plate. According to the above-described configuration having the three members, a junction area between each of the three members can be secured easily, and thereby the tank can have greater pressure resistance as a whole. 
     PRIOR ART LITERATURES 
     Patent Literature 
     Patent Literature 1: JP 2003-314987 A 
     Patent Literature 2: JP 2007-278556 A 
     SUMMARY OF INVENTION 
     According to studies conducted by the inventors of the present disclosure, the tank body of the tank disclosed in Patent Literature 1 may be made by pressing. In this case, a shear drop having an arc shape in cross section is formed in a corner of the junction area between the tank body and the intermediate plate. The sear drop of the tank body is stressed intensively when an inner pressure of the tank increases, and thereby the pressure resistance of the tank may deteriorate. 
     Accordingly, it is required to suppress the sear drop to reduce the stress applied to the sear drop intensively. For example, the shape of the corner of the junction area in cross section is necessary to be a square shape substantially. However, the pressing is required to be performed repeatedly so as to prevent the sear drop from being formed in the pressing. As a result, a quantity of machining processes increases, and thereby productivity may deteriorate. 
     The present disclosure addresses the above-described issues, and it is an objective of the present disclosure to provide a tank that can have pressure resistance certainly while improving productivity. 
     It is another objective to provide a heat exchanger having the tank that can have pressure resistance certainly while improving productivity. 
     According to a first aspect of the present disclosure, a tank has a passage in which a fluid flows. The passage and insides of tubes in which the fluid flows communicate with each other. The tubes are stacked in a stacking direction. 
     The tank has a tank body, a plate, and an intermediate plate. The tank body defines the passage therein. The tubes are attached to the plate. The intermediate plate has a plate shape and is arranged between the tank body and the plate. Each of the tubes has a longitudinal end in a longitudinal direction of the tubes. The longitudinal end connects to the passage through a communicating portion that is located between the passage and the longitudinal end. The passage has a round part having a round shape in cross section when viewed in the stacking direction. The round part includes at least a top located away from the tubes. The tank body has a space defining part and a tank junction part. The space defining part defines the passage. The tank junction part has a plate shape and is attached to the intermediate plate. 
     The longitudinal direction and the stacking direction of the tubes are perpendicular to a width direction. The space defining part has two end parts facing each other in the width direction. The two end parts connect to two of the tank junction part respectively. The space defining part has an inner wall surface on a side adjacent to the passage. The inner wall surface has a top located furthermost from the tubes in the inner wall surface. The tank body has a junction area in which the space defining part connects to the tank junction part. The junction area has a junction edge located closest to the tubes in the junction area when viewed in the stacking direction. The tank body has a shape satisfying expressions given by D 1 &gt;D 2  and D 2 ×L≥A 1 . D 1  represents a diameter of an inscribed circle including the top of the space defining part of the tank body when viewed in the stacking direction. D 2  represents a distance between the two junction edges facing each other in the width direction in the tank body when viewed in the stacking direction. L represents a length of the passage in the stacking direction. A 1  represents a total area of passage sectional areas of the tubes. 
     As described above, the tank body has a shape satisfying the expressions given by D 1 &gt;D 2  and D 2 ×L≥A 1 . Accordingly, it can suppress that stress is intensively applied to the junction part in which the space defining part connects to the tank junction part, i.e., to a corner of a junction part in which the tank body is attached to the intermediate part. In addition, a pressing process is not necessary to provide the junction area in which the space defining part connects to the tank junction part to have a square shape, thereby a quantity of machining processes can be reduced. Therefore, the tank can have high pressure resistance certainly while productivity is improved. 
     According to a second aspect of the present disclosure, a tank has a passage in which a fluid flows. The passage and insides of tubes in which the fluid flows communicate with each other. The tubes are stacked in a stacking direction. 
     The tank has a tank body, a plate, and an intermediate plate. The tank body defines the passage therein. The tubes are attached to the plate. The intermediate plate has a plate shape and is arranged between the tank body and the plate. Each of the tubes has a longitudinal end in a longitudinal direction of the tubes. The longitudinal end connects to the passage through a communicating portion that is located between the passage and the longitudinal end. The passage has a round part having a round shape in cross section when viewed in the stacking direction. The round part includes at least a top located away from the tubes. The tank body has a space defining part and a tank junction part. The space defining part defines the passage. The tank junction part has a plate shape and is attached to the intermediate plate. 
     The longitudinal direction and the stacking direction of the tubes are perpendicular to a width direction. The space defining part has two end parts facing each other in the width direction. The two end parts connect to two of the tank junction part respectively. The tank body has a junction end surface that has an arc shape protruding toward the passage when viewed in the stacking direction. The junction end surface is located adjacent to the passage and included in a junction area in which the space defining part connects to the tank junction part. The intermediate plate has a part corresponding to the junction end surface. The part is provided with a receiving surface that has an arc shape fitting the arc shape of the junction end surface. The receiving surface is attached to the junction end surface. 
     According to the second aspect, an inner wall surface of the tank body smoothly joins an inner side of the intermediate plate in a manner that the intermediate plate has a receiving surface that has the arc shape fitting the arc shape of the junction end surface. Accordingly, it can suppress that stress is intensively applied to the junction part in which the space defining part connects to the tank junction part, i.e., to a corner of a junction part in which the tank body is attached to the intermediate part. In addition, a pressing process is not necessary to provide the junction area in which the space defining part connects to the tank junction part to have a square shape, thereby a quantity of machining processes can be reduced. Therefore, the tank can have high pressure resistance certainly while productivity is improved. 
     According to a third aspect of the present disclosure, a heat exchanger has tubes, a pair of tanks, an inlet, and an outlet. The tubes are stacked in a stacking direction and define conduits in which a fluid flows respectively. Each of the tubes therein defines a passage in which a fluid flows. The pair of tanks extends in the stacking direction. The tubes connect the pair of tanks to each other. The inlet guides the fluid to flow into at least one tank of the pair of tanks. The outlet guides the fluid to flow out of the one tank. 
     Each of the pair of tanks has a plate, a tank body, and an intermediate plate. One longitudinal ends of the tubes are attached to the plate. The tank body is attached to the plate and has a passage extending in the stacking direction. The intermediate plate has a plate shape and is arranged between the tank body and the plate. 
     The tank body has a space defining part, a tank junction part, and an opening. The space defining part defines the passage such that at least a part of the passage has a round shape in cross section when viewed in the stacking direction. The tank junction part is attached to the intermediate plate. The tank junction part extends in a width direction perpendicular to both the stacking direction and a longitudinal direction of the tubes when viewed in the stacking direction. The space defining part has two end parts facing each other in the width direction. The two end parts connect to two of the tank junction parts respectively. The opening is defined between the two of the tank junction parts in the width direction. Insides of the tubes and the passage communicate with each other through the opening. At least the one tank has a tank inlet part that distributes the fluid, flowing from the inlet, to the plurality of tubes. 
     The tank body has a shape satisfying expressions given by: D 1 &gt;D 2  and D 2 ×L≥A×n. D 1  represents a diameter of a largest inscribed circle in cross sections of the passage when viewed in the stacking direction. D 2  represents a width of the opening in the width direction. L represents a length of the tank inlet part in the passage in the stacking direction. A represents a passage sectional area of each of the tubes connecting to the tank inlet part. The n represents a quantity of the tubes connecting to the tank inlet part. 
     According to the third aspect, it can be provide the heat exchanger that has the tank having high pressure resistance certainly while productivity is improved. 
     According to a fourth aspect of the present disclosure, a heat exchanger has tubes and a pair of tanks. The tubes are stacked in a stacking direction and define conduits in which a fluid flows respectively. Each of the pair of tanks extends in the stacking direction. The tubes connect the pair of tanks to each other. 
     Each of the pair of tanks has a plate, a tank body, and an intermediate plate. One longitudinal ends of the tubes are attached to the plate. The tank body is attached to the plate and has a passage extending in the stacking direction. The intermediate plate has a plate shape and is arranged between the tank body and the plate. 
     The tank body has a space defining part, a tank junction part, and an opening. The space defining part defines the passage such that at least a part of the passage has a round shape in cross section when viewed in the stacking direction. The tank junction part is attached to the intermediate plate. The tank junction part extends in a width direction perpendicular to both the stacking direction and a longitudinal direction of the tubes when viewed in the stacking direction. The space defining part has two end parts facing each other in the width direction. The two end parts connecting to two of the tank junction parts respectively. The opening is defined between the two of the tank junction parts in the width direction. Insides of the tubes and the passage communicate with each other through the opening. The intermediate plate has a plate hole through which the tubes and the passage communicate with each other. 
     The tank body has a shape satisfying expressions given by: D 1 &gt;D 2  and D 2 ×t 1 ≥A×n. D 1  represents a diameter of a largest inscribed circle in cross sections of the passage when viewed in the stacking direction. D 2  represents a width of the opening in the width direction. t 1  represents a thickness dimension of the plate hole in the stacking direction. A represents a passage sectional area of each of the tubes connecting to the tank inlet part. 
     Therefore, a heat exchanger that has the tank having high pressure resistance certainly while productivity is improved can be provided. 
     According to a fifth aspect of the present disclosure, a heat exchanger has tubes and a pair of tanks. The tubes are stacked in a stacking direction and define conduits in which a fluid flows respectively. The pair of tanks extends in the stacking direction. The tubes connect the pair of tanks to each other. 
     Each of the pair of tanks has a plate, a tank body, and an intermediate plate. One longitudinal ends of the tubes are attached to the plate. The tank body is attached to the plate and has a passage extending in the stacking direction. The intermediate plate has a plate shape and is arranged between the tank body and the plate. 
     The tank body has a space defining part and a tank junction part. The space defining part defines the passage such that at least a part of the passage has a round shape in cross section when viewed in the stacking direction. The tank junction part is attached to the intermediate plate. The tank junction part extends in a width direction perpendicular to both the stacking direction and a longitudinal direction of the tubes when viewed in the stacking direction. The space defining part has two end parts facing each other in the width direction. The two end parts connect to two of the tank junction parts respectively. 
     The tank body has a junction end surface that has an arc shape protruding toward the passage when viewed in the stacking direction. The junction end surface is located adjacent to the passage and included in a junction area in which the space defining part connects to the tank junction part. The intermediate plate has a part corresponding to the junction end surface. The part is provided with a receiving surface that has an arc shape fitting the arc shape of the junction end surface. The receiving surface is attached to the junction end surface. 
     According to the fifth aspect, a heat exchanger that has the tank having high pressure resistance certainly while productivity is improved can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. 
         FIG. 1  is a front view illustrating a refrigerant radiator according to a first embodiment. 
         FIG. 2  is a cross-sectional view illustrating tubes taken along a line perpendicular to a longitudinal direction of the tubes according to the first embodiment. 
         FIG. 3  is a cross-sectional view taken along a line III-III shown in  FIG. 1 . 
         FIG. 4  is a cross-sectional view taken along a line IV-IV shown in  FIG. 3 . 
         FIG. 5  is an exploded perspective view illustrating one of the tubes and a header tank according to the first embodiment. 
         FIG. 6  is a cross-sectional view illustrating a tank body when viewed in a tube stacking direction, according to the first embodiment. 
         FIG. 7  is an exploded cross-sectional view illustrating a tank body and an intermediate plate when viewed in the tube stacking direction, according to a second embodiment. 
         FIG. 8  is an exploded cross-sectional view illustrating a tank body and an intermediate plate when viewed in the tube stacking direction, according to a third embodiment. 
         FIG. 9  is a cross-sectional view illustrating a header tank according to a fourth embodiment. 
         FIG. 10  is an exploded cross-sectional view illustrating a tank body and an intermediate plate when viewed in the tube stacking direction, according to a fifth embodiment. 
         FIG. 11  is a cross-sectional view illustrating one of tubes and a header tank when viewed in the tube stacking direction, according to a modification. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will be described hereafter referring to drawings. In the embodiments, a part that corresponds to or equivalents to a matter described in a preceding embodiment may be assigned with the same reference number, and a redundant description may be omitted. When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination. 
     (First Embodiment) 
     A first embodiment will be described hereafter referring to  FIG. 1  through  FIG. 6 . According to the present embodiment, a tank of the present disclosure is applied to a header tank of a refrigerant radiator that is disposed in a supercritical refrigeration cycle using carbon dioxide (CO 2 ) as refrigerant. The supercritical refrigeration cycle is a refrigeration cycle that may use, other than carbon dioxide, ethylene, ethane, nitric oxide etc. as the refrigerant. A pressure on a high-pressure side in the supercritical refrigeration cycle exceeds a critical pressure of the refrigerant. 
     As shown in  FIG. 1 , a refrigerant radiator  100  is a heat exchanger that performs a heat exchange between the refrigerant flowing in tubes  110  and air flowing outside the tubes  110 . According to the present embodiment, the refrigerant corresponds to a fluid, and the air corresponds to another fluid. 
     The refrigerant radiator  100  has a core  101  and a pair of header tanks  140 . Each member configuring the core  101  and the pair of header tanks  140  is made of aluminum or an aluminum alloy. The members configuring the core  101  and the pair of header tanks  140  are assembled by a method such as fitting and a fixing using a jig and are joined together by brazing. A brazing material is applied to surfaces of the members as required in advance. 
     The core  101  has the tubes  110  and fins  120 . The tubes have a flat shape in cross section and define conduits in which refrigerant flows respectively. The fins  120  have a corrugated shape. The tubes  110  and the fins  120  are stacked alternately with each other. 
     A longitudinal direction of the tubes  110  will be referred to as a tube longitudinal direction hereafter. A stacking direction in which the tubes  110  and the fins  120  are stacked will be referred to as a tube stacking direction. A direction perpendicular to both the tube longitudinal direction and the tube stacking direction will be referred to as a width direction. 
     Each of the tubes  110  has conduits  110   a  therein. The conduits  110   a  are arranged in a longitudinal direction of the flat shape of the tubes  110 . Specifically, as shown in  FIG. 2 , a quantity of the conduits  110   a  provided in each of the tubes  110  is nine, and the conduits  110   a  has a circular shape in cross section. Accordingly, a passage sectional area A of each of the tubes  110  is equal to a total area of passage sectional areas of the conduits  110   a.  That is, when each of the tubes  110  has a single conduit, the passage sectional area A of each of the tubes  110  is equal to a passage sectional area of the single conduit. The tubes  110  are formed by extrusion molding. 
     As shown in  FIG. 1 , the core  101  has two edges facing each other in the tube stacking direction, and a side plate  130  is attached to each of the two edges. The side plate  130  reinforces the core  101 . The side plate  130  extends parallel to the tube longitudinal direction and has two end parts in the tube longitudinal direction. The two end parts are attached to the header tanks  140  respectively. 
     The header tanks  140  are located on both sides of the tubes  110  in the tube longitudinal direction respectively, and extend in a direction (i.e., the tube stacking direction) perpendicular to the tube longitudinal direction. The header tanks  140  communicate with the tubes  110 . According to the present embodiment, the header tanks  140  are located on horizontal sides of the tubes  110  facing each other in horizontal direction, and extend in vertical direction to communicate with the tubes  110 . 
     More specifically, each of the header tanks  140  has a passage  151  therein. The header tanks  140  and the tubes  110  are coupled with each other by brazing such that an inside of the passage  151  and insides of the tubes  110  communicate with each other. Each of the header tanks  140  has longitudinal ends (i.e., ends in the tube stacking direction), and an end cap  180  is attached to each of the longitudinal ends by brazing. The end cap  180  seals an opening of the passage  151  provided in the header tanks  140 . 
     One header tank  140  of the pair of header tanks  140  has a separator  141 . The separator  141  is located in the one header tank  140  and partitions the passage  151 . The separator  141  is attached to the one header tank  140  by brazing. The one header tank  140  is located on a left side on a condition of being illustrated in  FIG. 1 . The one header tank  140  has an inlet joint  191 . The inlet joint  191  is located above the separator  141  and attached to the one header tank  140  by brazing. The inlet joint  191  provides an inlet, and the refrigerant flows into the passage  151  from the inlet. The one header tank  140  further has an outlet joint  192 . The outlet joint  192  is located below the separator  141  and attached to the one header tank  140  by brazing. The outlet joint  192  provides an outlet, and the refrigerant flows out of the passage  151  from the outlet. 
     A configuration of the header tanks  140  of the present embodiment will be described in detail hereafter. As shown in  FIG. 3 ,  FIG. 4 , and  FIG. 5 , each of the header tanks  140  has a tank body  150 , a plate  160 , and an intermediate plate  170 . The tank body defines the passage  151 , in which the refrigerant flows, therein. The tubes  110  are attached to the plate  160 . The intermediate plate  170  has a plate shape and is arranged between the tank body  150  and the plate  160 . 
     The tank body  150  has a space defining part  152  and a tank junction part  153 . The space defining part  152  defines the passage  151 . The tank junction part  153  is attached to the plate  160  and the intermediate plate  170 . 
     As shown in  FIG. 3  and  FIG. 4 , the space defining part  152  has a substantially arc shape in cross section when viewed in the tube stacking direction. That is, the space defining part  152  is provided such that at least a part of an inner wall surface of the space defining part  152  has substantially arc shape. The inner wall surface is, i.e., a surface adjacent to the passage  151 . Accordingly, the passage  151  has a round part that has a round shape and includes a top  154  located furthermost from the tubes  110 , in cross section of the passage  151  viewed in the tube stacking direction. 
     The space defining part  152  has an opening  155  on a side adjacent to the tubes  110  (i.e., a side adjacent to the intermediate plate  170 ). One longitudinal ends of the tubes  110  in the longitudinal direction and the passage  151  communicate with each other through the opening  155 . The one longitudinal ends of the tubes  110  will be referred to as tube ends  111  hereafter. 
     The space defining part  152  has two ends facing each other in the width direction. The tank junction part  153  has a plate shape and connects the two ends to each other. In other words, the space defining part  152  has one end and an other end facing each other in the width direction, and the tank junction part  153  connects to each of the one end and the other end. As a result, the opening  155  is located between two of the tank junction part  153  when viewed in the tube stacking direction. The space defining part  152  and the tank junction part  153  are provided integrally with each other. 
     The tank body  150  having the above-described space defining part  152  and the tank junction part  153  is provided by pressing a flat plate that is cladded with (i.e., coated with) a brazing material in advance. The brazing material covers a surface of the flat plate on the side adjacent to the tubes  110 . The brazing material may cover the one surface and another surface of the flat plate facing the one surface. 
     The plate  160  has a substantially U-shape. Specifically, the plate  160  has two bent portions extending in one direction when viewed in the tube stacking direction. More specifically, the plate  160  has a flat part  161  and ribs  162 . The flat part  161  has a rectangular flat shape and has two ends facing each other in the width direction. The ribs  162  connect to the two ends of the flat part  161  respectively. The flat part  161  and the ribs  162  are provided integrally with each other. 
     The flat part  161  of the plate  160  is provided with a tube insert hole  163  to which the tube end  111  is inserted. The plate  160  is provided by pressing a flat plate that is cladded with a brazing material on both of a top side and a bottom side facing each other. 
     The intermediate plate  170  has a rectangular flat shape. The intermediate plate  170  has a part corresponding to the tube end  111 , and the part is provided with a plate hole  171  passing through the intermediate plate  170  in a thickness direction of the intermediate plate  170 . As shown in  FIG. 5 , the plate hole  171  has a longitudinal end part provided with a stepped portion  172 . The stepped portion  172  is provided as a position setting portion that sets a position of the tube end  111  in the thickness direction. 
     A thickness dimension t 1  of the plate hole  171  in the thickness direction is larger than a thickness dimension t 2  of the each tube  110  in the thickness direction. The dimension t 1  is, i.e., a length of the plate hole  171  in the tube stacking direction. The thickness dimension t 2  is, i.e., a dimension of each tube  110  in a transverse direction in the flat cross-sectional shape or a length of each tube  110  in the tube stacking direction. According to the present embodiment, the thickness dimension t 1  is about twice as large as of the thickness dimension t 2 . The intermediate plate  170  is different from the tank body  150  and the plate  160  in a point that the intermediate plate  170  is configured by a bare member of which surface is not cladded. 
     The tank body  150 , the intermediate plate  170 , plate  160 , and the tubes  110  having the above-described configurations are assembled as shown in  FIG. 3  and  FIG. 4 . A location of an edge  112  of the tube end  111  is set to be located in an area outside the passage  151  by the stepped portion  172  of the plate hole  171  provided in the intermediate plate  170 . The tube end  111  is located inside the plate hole  171 . 
     The opening  155  of the tank body  150  and the plate hole  171  of the intermediate hole  170  provide a communicating portion through which the tube end  111  connects to the passage  151 . The members  150 ,  170 ,  160 ,  110  are brazed integrally by a brazing material applied to the tank body  150  and the plate  160 . 
     The tank body  150  of the present embodiment will be described in detail hereafter referring to  FIG. 6 . The tank body  150  has a surface adjacent to the passage  151  defining a junction area in which the space defining part  152  connects to the tank junction part  153 . The surface will be referred to as a junction end surface  156 . 
     The junction end surface  156  inclines from an inside to an outside in the width direction (i.e., from an inside to an outside of a paper showing  FIG. 6 ) as being distanced away from the tube  110  in the tube longitudinal direction (from a lower side to an upper side of the paper showing  FIG. 6 ). According to the present embodiment, the junction end surface  156  has an arc shape that is recessed toward the outside in the width direction. More specifically, the junction end surface  156  is located on a circle defined by the inner wall surface of the space defining part  152  having the substantially arc shape. Therefore, the junction end surface  156  and the inner wall surface (i.e., an arc surface) connect to each other smoothly. 
     The inner wall surface of the space defining part  152  included in the tank body  150  has a top  157  located furthermost from the tube end  111 . The tank body  150  has the junction area in which the space defining part  152  connects to the tank junction part  153 . The junction area has a junction edge  158  located closest to the tube end  111  when viewed in the tube stacking direction. Since the junction end surface  156  has the arc shape, the junction end surface  156  has one edge and an other edge facing each other in the width direction. According to the present embodiment, each of the one edge and the other edge has the junction edge  158 . 
     Here, D 1  represents a diameter of an inscribed circle (shown by a dashed line in  FIG. 6 ) including the top  157  of the space defining part  152  when viewed in the stacking direction. In other words, D 1  represents a diameter of an inscribed circle having the largest diameter in the passage  151  when viewed in the tube stacking direction. 
     D 2  represents a distance between the two junction edges  158  of the tank body  150  facing each other in the width direction when viewed in the stacking direction. That is, D 2  represents a distance between the junction edge  158  provided in the one edge and the junction edge  158  provided in the other edge in the width direction. In other words, D 2  represents a width of the opening  155 . 
     L represents a length of the passage  151  in the stacking direction. Specifically, the header tank  140  has a tank inlet part  140   a  that distributes the fluid, flowing from the inlet joint  191 , to the tubes  110 . According to the present embodiment, the tank inlet part  140   a  is a part of the one header tank  140  and is located above the separator  141 . As shown in  FIG. 1 , the length L is, i.e., a length of the tank inlet part  140   a  in the passage  151  in the tube stacking direction. 
     A 1  represents a total area of passage sectional areas of the tubes  110 . Specifically, a passage sectional area A of each of the tubes  110  multiplied by a quantity n of the tubes  110  attached to the tank inlet part  140   a  equals the total area A 1  of the passage sectional areas (i.e., A×n=A 1 ). The tank body  150  of the present embodiment has a shape satisfying expressions of D 1 &gt;D 2  and D 2 ×L≥A 1  (i.e., D 2 ×L≥A×n). 
     As described above, the tank body  150  is configured to satisfy the expression of D 1 &gt;D 2 . 
     Accordingly, it can suppress that a sear drop is formed in a corner of a junction area in which the space defining part  152  and the tank junction part  153  connect to each other, i.e., in which the tank body  150  is attached to the intermediate plate  170 . Therefore, it can suppress that stress is applied to the sear drop intensively even when a pressure inside the header tank  140  increases. 
     In addition, the pressing is not required to be performed repeatedly so as to provide the junction area, in which the space defining part  152  connects to the tank junction part  153 , to be a square shape when providing the tank body  150  by pressing. Accordingly, a deterioration of the productivity can be suppressed. Therefore, the header tank  140  of the present embodiment can certainly have high pressure resistance while productivity is improved. 
     Moreover, a pressure inside the tank body  150  applies a stress to the junction edge  158  in a direction in which the junction edge  158  is pressed against intermediate plate  170  by configuring the tank body  150  to satisfy the expression of D 1 &gt;D 2 . The direction in which junction edge  158  is pressed against the intermediate plate  170  is, i.e., a radial outward direction of the inscribed circle of the passage  151  shown by the dashed line in  FIG. 6 . As a result, the tank body  150  and the intermediate plate  170  can be prevented from being separated from each other even when the brazing between the tank body  150  and the intermediate plate  170  is insufficient. Therefore, the pressure resistance can be secured certainly. 
     Here, an opening area of the opening  155  of the tank body  150  becomes small when the distance (D 2 ) between the junction edges  158 , adjacent to each other in the width direction when viewing the tank body  150  in the tube stacking direction, is set too small. In this case, a pressure loss of the fluid flowing in or flowing out of the passage  151  may increase. 
     According to the present embodiment, the tank body  150  has a shape satisfying an expression of D 2 ×L≥A 1 . As a result, the opening area (D 2 ×L) of the opening  155 , which is an inlet/outlet of the tank body  150  with respect to the passage  151 , can be larger than or equal to the total area (A 1 ) of the passage sectional areas of the tubes  110 . Therefore, an increase of the pressure loss of the fluid flowing in or flowing out of the passage  151  can be suppressed. 
     (Second Embodiment) 
     A second embodiment will be described hereafter referring to  FIG. 7 . The second embodiment is different from the above-described first embodiment in configurations of the tank body  150  and the intermediate plate  170 . 
     As shown in  FIG. 7 , the space defining part  152  of the tank body  150  has substantially a U-shape in a cross section when viewed in the tube stacking direction. The junction end surface  156  of the tank body  150  has an arc shape protruding toward the passage  151 . 
     The intermediate plate  170  has the part corresponding to the junction end surface  156 . The part is provided with a protruding portion  173  that protrudes toward the tank body  150  (i.e., upward in a paper showing  FIG. 7 ). The protruding portion  173  has substantially a triangular shape in a cross section when viewed in the tube stacking direction. The protruding portion  173  has a receiving surface  174  and a vertical surface  175 . The receiving surface  174  is attached to the junction end surface  156  of the tank body  150 . The receiving surface  175  is perpendicular to the width direction. 
     The receiving surface  174  has an arc shape fitting the arc shape of the junction end surface  156 . That is, the receiving surface  174  has the same arc shape as that of the junction end surface  156 . 
     The vertical surface  175  connects to an edge of the receiving surface  174  on a side adjacent to the tank body  150 . The vertical surface  175  connects to the inner wall surface of the space defining part  152  smoothly. That is, the vertical surface  175  and the inner wall surface of the space defining part  152  provide a seamless single flat surface. In other words, the vertical surface  175  and the inner wall surface of the space defining part  152  connect to each other without providing any step. 
     As described above, the protruding portion  173  of the intermediate plate  170  is provided with the receiving surface  174  having the arc shape fitting the arc shape of the junction end surface  156  of the tank body  150 . Accordingly, the inner wall surface of the tank body  150  and an inner wall surface of the intermediate plate  170  can connect to each other smoothly. 
     Accordingly, it can suppress that an insufficient junction part is formed in the junction part in which the space defining part  152  connects to the tank junction part  153 , i.e., in a corner of a junction part in which the tank body  150  is attached to the intermediate part  170 . Therefore, it can suppress that stress is intensively applied to the corner of the junction part in which the tank body  150  is attached to the intermediate part  170  when the pressure inside the header tank  140  increases. 
     In addition, the pressing process is not necessary to provide the junction area in which the space defining part  152  connects to the tank junction part  153  to have a square shape, thereby a quantity of machining processes can be reduced. Therefore, the header tank  140  of the present embodiment can certainly have high pressure resistance while productivity is improved. 
     (Third Embodiment) 
     A third embodiment will be described hereafter referring to  FIG. 8 . The third embodiment is different from the second embodiment in a configuration of the intermediate plate  170 . 
     As shown in  FIG. 8 , the intermediate plate  170  of the present embodiment has an intermediate junction part  176  and a protruding part  177 . The intermediate junction part  176  is attached to the tank junction part  153  of the tank body  150 . The protruding part  177  is located closer to the top  154  of the tank body  150  as compared to the intermediate junction part  176 . The intermediate junction part  176  and the protruding part  177  have a plate shape extending in a direction perpendicular to the tube stacking direction. The intermediate junction part  176  is provided integrally with the protruding part  177 . 
     The protruding part  177  has the plate hole  171 . That is, the protruding part  177  is provided with a communicating portion through which the tube end  111  connects to the passage  151 . 
     The protruding part  177  has two edges facing each other in the width direction, and two of the intermediate junction parts  176  connect to the two edges of the protruding part  177  respectively. The intermediate junction part  176  and the protruding part  177  connect to each other in a junction. A surface of the junction adjacent to the tank body  150  is attached to the junction end surface  156 . Accordingly, the surface of the junction in which the intermediate junction part  176  and the protruding part  177  connect to each other configures the receiving surface  174  that is attached to the junction end surface  156  of the tank body  150 . 
     As described above, according to the present embodiment, the intermediate junction part  176  and the protruding part  177  connect to each other in the junction. The junction has the receiving surface  174  having the arc shape fitting the arc shape of the junction end surface  156  of the tank body  150 . As a result, the inner wall surface of the tank body  150  and the inner wall surface of the intermediate plate  170  can connect to each other smoothly, thereby the same effects as the second embodiment can be obtained. 
     (Fourth Embodiment) 
     According to the present embodiment, a distance D 2  between the junction edges  158  of the tank body  150  in the width direction, a thickness dimension t 1  of the plate hole  171 , and the passage sectional area A of each of the tubes  110  are defined as shown in  FIG. 9 .  FIG. 9  illustrates a diagram corresponding to a cross sectional view taken along a line IX-IX shown in  FIG. 3  regarding the first embodiment. 
     Specifically, the header tank  140  of the present embodiment has a shape satisfying an expression of D 2 ×t 1 ≥A. That is, the header tank  140  of the present embodiment has the shape satisfying expressions of D 1 &gt;D 2 , D 2 ×L≥A×n, and D 2 ×t 1 ≥A. Other configurations of the refrigerant radiator  100  are the same as the first embodiment. 
     Therefore, according to the header tank  140  and the refrigerant radiator  100  of the present embodiment, the same effects as the first embodiment can be obtained. 
     The communicating part  155 ,  171  has a part to which one tube  110  is connected. An opening area (expressed by D 2 ×t 1 ) of the part can be set larger than the passage sectional area A of each of the tubes  110 . As a result, an increase of a pressure loss caused when the refrigerant flows into the passage  151  from the tubes  110  can be suppressed more effectively. Alternatively, an increase of a pressure loss caused when the refrigerant flows into the tubes  110  from the passage  151  can be suppressed more effectively. 
     (Fifth Embodiment) 
     The present embodiment is different from the third embodiment in a configuration of the intermediate plate  170  in the header tank  140 . 
     Specifically, according to the present embodiment, the protruding part  177  of the intermediate plate  170  protrudes toward the passage  151  over the end of the receiving surface  174  adjacent to the passage  151  as shown in  FIG. 10 . The protruding part  177  has side surfaces facing each other in the width direction, and the side surfaces has flat surfaces  174   a  respectively. The flat surfaces  174   a  are attached to the inner wall surface of the space defining part  152  by brazing.  FIG. 10  illustrates a cross-sectional view corresponding to the cross-sectional view in  FIG. 8  regarding the third embodiment. 
     The flat surfaces  174   a  expand parallel to the tube stacking direction and the tube longitudinal direction. The inner surface of the space defining part  152  has flat surfaces  156   a  to which the flat surfaces  174   a  are attached respectively. Other configurations of the refrigerant radiator  100  are the same as the first embodiment. 
     Therefore, according to the header tank  140  and the refrigerant radiator  100  of the present embodiment, the same effects as the third embodiment can be obtained. 
     Moreover, the flat surfaces  174   a  of the protruding part  177  are attached to the inner wall surface of the space defining part  152 , in addition to the attachment between the tank junction part  153  of the tank body  150  and the intermediate junction part  176  of the intermediate plate  170 . The junctions can cover the junction end surface  156  in which the sear drop is easily formed by the pressing. As a result, stress can be prevented, more effectively, from being applied intensively to the corner of the junction area in which the tank body  150  is attached to the intermediate plate  170  when the pressure inside the header tank  140  increases. 
     (Modifications) 
     It should be understood that the present disclosure is not limited to the above-described embodiments and intended to cover various modification within a scope of the present disclosure, for example, as described hereafter. It should be understood that structures described in the above-described embodiments are preferred structures, and the present disclosure is not limited to have the preferred structures. The scope of the present disclosure includes all modifications that are equivalent to descriptions of the present disclosure or that are made within the scope of the present disclosure. 
     (1) According to the above-described embodiments, three components (the tank body  150 , the plate  160 , and the intermediate plate  170 ) configuring the header tank  140  are assembled (fixed temporary) by a method such as fitting or fixing using a jig, and then joined together by brazing. However, a method for joining the three components  150 ,  160 , and  170  are not limited to the above-described example. 
     For example, as shown in  FIG. 11 , the ribs  162  of the plate  160  may have clicks  164  as a swaging part. In this case, the three components  150 ,  160 ,  170  are deformed plastically and fixed temporary by the clicks  164 , and then joined together by brazing. 
     (2) According to the above-described first embodiment, the tank body  150  is formed by pressing. However, the tank body  150  may be formed by extrusion molding. 
     (3) According to the above-described embodiment, single passage  151  of the header tank  140  is provided, and any other passage  151  is arranged adjacent to the single passage  151  in the width direction. However, more than one of the passage  151  may be arranged in the width direction similar to the tubes  110 . 
     (4) According to the above-described embodiments, the tank of the present disclosure is applied to the refrigerant radiator  100  disposed in the supercritical refrigeration cycle. However, the tank of the present disclosure may be applied to an evaporator that evaporates the refrigerant. Alternatively, the tank of the present disclosure may be applied to a heat exchanger for a vehicle engine etc. Furthermore, the refrigerant cycle is not limited to the supercritical refrigeration cycle using carbon dioxide as the refrigerant, and may be a normal refrigeration cycle. The tank of the present disclosure may be applied to a device other than the heat exchanger. 
     (5) According to the above-described embodiments, both the inlet joint  191  and the outlet join  192  are attached to the one header tank  140 . However, the inlet joint  191  may be attached to the one header tank  140 , and the outlet joint  192  may be attached to the other header tank  140 . That is, the inlet joint  191  and the outlet join  192  may be attached to different header tanks  140  respectively.