JP4998163B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a so-called dogbone type fin-and-tube heat exchanger used as a cooler (evaporator) in a household or commercial refrigerator, a showcase or the like.

  Conventionally, this type of heat exchanger is arranged in a plurality of rows and stages, and is composed of a heat transfer tube in which a refrigerant flows and a plurality of fins in which the heat transfer tube is inserted and air flows between them. ing. The heat transfer tubes are connected to each other to form a refrigerant flow path of at least one circuit. Generally, a pipe heater fitting notch is formed on the end face of the fin, and a defrosting pipe heater is provided. It arrange | positions at the heat exchanger lower surface (for example, refer patent document 1).

  FIG. 6 shows a cross section of the heat exchanger described in Patent Document 1. As shown in FIG. 6, the heat exchanger is composed of a plurality of rows and stages of heat transfer tubes 21 and a plurality of fins 22 into which the heat transfer tubes 21 are inserted, and the heat transfer tubes 21 meander. The refrigerant flow path is configured. A notch for fitting a pipe heater is formed on the end face of the fin 22, and a pipe heater for defrosting that is bent in a meandering manner so that the straight pipe portion and the curved pipe portion are continuous in this notch. 23 is attached. As a result, the heat exchanger has a configuration in which the defrosting pipe heater 23 is arranged on the lower surface.

  The operation of the heat exchanger configured as described above will be described below.

  First, the refrigerant flows through the configured refrigerant flow path and evaporates in the flow path, thereby removing heat and cooling the heat exchanger. When air is circulated by a fan or the like, the airflow passes through the surface of the fin 22 as indicated by an arrow, and the temperature becomes low, for example, flows into the refrigerator, thereby cooling the interior of the refrigerator or the like.

  As time elapses, frost adheres to the heat exchanger. However, the pipe heater 23 is periodically energized to heat, and a heat conduction path is generated as indicated by an arrow to melt the attached frost.

  Usually, a temperature detection sensor is disposed in the vicinity of the upper surface of the heat exchanger, detects that a certain temperature has been reached, and the defrosting ends by stopping energization of the pipe heater 23.

  In addition, since this kind of heat exchanger comprises the refrigerant | coolant flow path by connecting the heat exchanger tube 21, since there are many joining locations, the possibility of the refrigerant | coolant leak by poor joining is not zero. If the heat transfer tube is copper and a copper alloy, joining is relatively easy. However, if the heat transfer tube 21 is aluminum or an aluminum alloy, it is not suitable because of difficulty in joining.

Therefore, it is common to use relatively expensive copper and copper alloys, except when using a hydrocarbon-based refrigerant, or when not paying much attention to reliability or cost rationalization.
Japanese Patent Application Laid-Open No. 2004-3395

  However, since the refrigerant flow path is configured by connecting the heat transfer tubes 21 in the above-described conventional configuration, since there are many joint portions, there is a high possibility of refrigerant leakage due to poor bonding. Since copper and copper alloys, which are relatively easy to join, must be used, there are problems in terms of reliability and cost.

  Therefore, one pipe body is bent in a plurality of rows and steps, and a meandering refrigerant tube in which the straight pipe portion and the curved pipe portion are continuous is formed into a dogbone-shaped long hole provided in the plate fin. By using a heat exchanger configured to be inserted and penetrated, the number of joints in the refrigerant flow path can be reduced, and a heat exchanger that ensures reliability by eliminating the possibility of refrigerant leakage due to poor joining as much as possible It has been known.

  In addition, a heat exchanger has been developed in which a serpentine-like refrigerant tube formed by continuously bending an aluminum refrigerant tube that is difficult to join is applied to such a heat exchanger.

  FIG. 7 shows a cross-sectional structure of the heat exchanger having such a configuration.

  However, when the serpentine tube 31 is formed by continuously bending the refrigerant tube, it is necessary to process a plurality of long holes 33 in the plate fin 32 as shown in FIG.

  When such a long hole 33 is formed, the heat transfer path becomes a detour path that is bent with the straight path due to the space associated with the formation of the long hole. As a result, the amount of heat transfer by the straight path increases, and the defrosting pipe heater 34 is formed. The heat conduction from the heat sink is not uniform throughout the fins, creating places that are difficult to be defrosted, creating defrost spots, and defrosting more than necessary to eliminate the defrost spots. It had the subject that defrosting did not go well, such as setting operating time long.

  More specifically, the frost adhering to the heat exchanger falls to a drain pan (not shown) when melted to some extent, and the frost on the drain pan is (substantially) completely melted by the radiant heat of the defrosting pipe heater 34. Control that completes defrosting is common.

  In the case of the configuration shown in FIG. 7, the frost around the long hole 33 falls almost without melting. In addition, some of them may be caught in the lower serpentine tube 31 and remain in the heat exchanger. Even if some frost remains in the heat exchanger, the heat exchanger ventilation conditions are improved, so the temperature of the heat exchanger rises faster, and the sensor ( (Not shown) may detect the temperature, and may recognize the end of defrosting and end the defrosting operation.

  Therefore, although the frost remains in the drain pan or the heat exchanger, the defrosting end time becomes faster, and when the cooling operation is restarted in that state, the drain frost or the remaining frost grows greatly, There was also a risk of poor cooling.

  The present invention solves the above-described conventional problems, and provides a heat exchanger that is composed of a serpentine-like continuous refrigerant tube that is inexpensive in terms of reliability and cost, and that can achieve a uniform temperature for defrosting. The purpose is to do.

  In order to solve the above-described conventional problems, the heat exchanger according to the present invention is bent in a meandering manner at a predetermined pitch so that a plurality of rows and stages are continuously formed in the straight pipe portion and the curved pipe portion. In a heat exchanger in which a refrigerant tube is passed through a long hole provided in a plate fin, the heat exchanger is arranged so that the long diameter of the long hole is in a horizontal direction, and a defrosting heater is further provided on the lower surface of the heat exchanger. Further, linear heat shield holes extending intermittently at predetermined intervals and extending in the horizontal direction are provided between the long holes arranged in the row direction of the plate fins.

  As a result, it is possible to apply a refrigerant tube in the form of a serpentine tube by continuously bending an aluminum tube body that is difficult to join, ensuring superiority in terms of reliability and cost. By performing so-called perforate processing in which cut portions are intermittently arranged, the temperature of the defrost can be equalized.

  The heat exchanger of the present invention does not impair the reliability, cost, etc. of the heat exchanger as a serpentine refrigerant tube, and is stable without defrosting spots by using perforated plate fins. Can be defrosted.

According to the first aspect of the present invention, there is provided a refrigerant tube bent in a meandering manner at a predetermined pitch so that a plurality of rows and steps are continuously formed in a straight pipe portion and a curved pipe portion, and a length of a dogbone shape. A heat exchanger having a plurality of plate fins provided on a plate surface, a plurality of the plate fins arranged with a space between each other, and the refrigerant tube passing through the long hole, provided on the plate fin. Further, a defrosting heater is disposed on the lower surface of the heat exchanger, and a predetermined interval is provided between the long holes arranged in the row direction of the plate fins. A linear heat shield hole extending intermittently every time and extending in the horizontal direction is provided , and the heat shield hole extends below the straight pipe portion of the refrigerant tube and has a predetermined dimension in the left-right direction around the straight pipe portion. And a substantially central position between adjacent heat shield holes and A non-heat shielding part that is not processed so as to allow heat conduction is provided at a substantially central position of the long hole, the long hole, the heat shielding hole, the non-heat shielding part, The positional relationship of the defrosting heater is such that the defrosting heater is disposed so as to overlap the central part of the long diameter of the long hole and the non-heat shielding part on the projection surface from above .

  By adopting such a configuration, in the process in which heat from the defrosting heater is transmitted radially upward of the heat exchanger, heat is transferred so as to deviate from the linear heat transfer path and the linear heat transfer path. As a result, a bypass path is formed, and heat is quickly transferred to the upper end of the heat exchanger, and a heat transfer path is formed so as to wrap the elongated hole. It is possible to prevent the inside of the heat exchanger from becoming non-uniform so that the surrounding frost is not easily melted and the other portions are easily melted, and to equalize the temperature. Therefore, the heat exchanger excellent in defrosting efficiency can be obtained by comprising the serpentine refrigerant tube and the perforated plate fin.

  The invention according to claim 2 is the invention according to claim 1, wherein the total length of the heat shield holes in the step direction is set longer than the total length of the mutual interval between the heat shield holes.

  As a result, in the process in which the heat from the defrosting heater is transferred upward, the heat shield hole blocks the heat conduction in the part where heat transfer is fast except at the periphery of the long hole, and the heat is removed. Detour to non-heat shielding part. As a result, the heat transfer speed is controlled to eliminate the places where frost is difficult to melt and where it is easy to melt, preventing the heat exchanger from becoming non-uniform temperature and achieving more uniform temperature. .

  And, by setting the length of the heat shield holes longer than the distance between the heat shield holes, the heat transfer path can be formed finely, and as a result, the heat can be distributed and transmitted to the entire heat exchanger. Further, the temperature of the heat exchanger can be further equalized.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the length dimension of the heat shield hole is set shorter than the bending pitch dimension of the refrigerant tube.

  As a result, the heat shield holes can be formed in conjunction with the formation of the long holes, so that the feed pitch of the mold for molding the plate fins can be made constant, and the equipment control can be simplified. It is possible.

  A fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the defrosting heater is disposed at substantially the center position of the long diameter of the long hole provided in the lowermost row. It is.

  As a result, the heat from the defrosting heater is conducted and dispersed substantially evenly along the major axis direction of the long hole, so that heating spots of the heat exchanger due to heat conduction bias can be suppressed, and the temperature of the entire heat exchanger can be controlled. (The supply of heat according to the amount of frost formation) is stabilized and the defrosting performance can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the same reference numerals are given to the same configurations as those of the conventional example or the above-described embodiments, and detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
1 is a perspective view of a heat exchanger according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view of the heat exchanger taken along line AA of FIG. 1, and FIG. 3 is a plate fin of the heat exchanger. It is a schematic diagram which shows the path | route of the heat transfer in.

  1 and 2, the heat exchanger 1 is arranged at predetermined intervals between a refrigerant tube 2 in which refrigerant flows inside, a pair of end plates 3 arranged at predetermined intervals, and the end plates 3. A plurality of plate fins 4 and a defrosting pipe heater (hereinafter referred to as a heater) 5 disposed on the lower surface of the heat exchanger 1 are provided.

  The refrigerant tube 2 is formed in a meandering manner so that a single pipe body made of aluminum or an aluminum alloy has a straight pipe portion and a curved pipe portion that are continuous in a row (vertical) direction X and a step (left / right) direction Y. The serpentine tube is bent into a single, and one refrigerant flow path is formed without using a connecting pipe that forms a curved pipe portion.

  Further, the end plate 3 and the plate fin 4 are provided with long holes (a dogbone-shaped long hole for the plate fin 4) 6 at predetermined intervals. Is set in accordance with the bending pitch (bending diameter) P of the bent pipe portion. In the first embodiment, the bending pitch P and the arrangement interval T of the refrigerant tube 2 are set to the same dimension.

  And the refrigerant | coolant tube 2 penetrates the long hole 6 of the end plate 3 and the plate fin 4, and is comprised, and the heat exchanger 1 is comprised.

  In the first embodiment, the refrigerant circuit is formed so that the refrigerant flows from the lower stage to the upper stage in FIG.

  Like the refrigerant tube 2, the heater 5 is bent into a meandering shape in which the curved pipe portion and the straight pipe portion are continuous, and is fitted into a semicircular cutout 7 formed at the lower edge of each plate fin 4. It is fixed by appropriate means.

  The heat exchanger 1 is arranged in a main body device (not shown) such that the long diameter M of the long hole 6 is substantially horizontal, and the heater 5 has its straight pipe portion as shown in FIG. However, it arrange | positions so that it may not overlap with the straight pipe | tube part of the refrigerant | coolant tube 2 in the projection surface from the top.

  Further, the plate fins 4 are provided with linear heat shield holes 8 that are intermittently extended at predetermined intervals between the long holes 6 arranged in the step direction. The heat shield hole 8 is specifically a slit that is cut (cut) by a blade jig (not shown), and thereby heat conduction is partially blocked. Therefore, the heat shield hole 8 is not limited to a slit, and may be an elongated through hole.

  The heat shield hole 8 is below the straight pipe portion of the refrigerant tube 2 and extends in the left-right direction around the straight pipe portion, and is located between adjacent heat shield holes 8 (arrangement interval T). A non-heat-shielding portion 9 that is not processed so as to allow heat conduction is provided at a substantially central position and a substantially central position of the long hole 6.

  The total length of the dimension L of the heat shield hole 8 in the step direction of the plate fin 4 is in the range of about 2 to about 4 times the total length of the dimension l of the non-heat shield portion 9 in the step direction. Is set.

  With the above configuration, the positional relationship among the long hole 6, the heat shielding hole 8, the non-heat shielding part 9, and the heater 5 is as shown in FIG. The heaters 5 are arranged so as to overlap the non-heat shielding portions 9 respectively, and the heat shielding holes 8 are positioned below the refrigerant tubes 2 in the step direction over all rows except the bottom row as described above.

  In the following description, a configuration in which the heat shield holes 8 and the non-heat shield portions 9 are alternately and continuously formed will be referred to as perforate processing.

  About the heat exchanger comprised as mentioned above, the defrost operation | movement at the time of being used as an evaporator of a refrigerating cycle is demonstrated.

  When ventilation is performed in the direction indicated by the arrow Z in FIG. 2, the frosting state on the heat exchanger 1 usually starts from the windward tip of the plate fin 4, spreads and adheres to the refrigerant tube 2 side, and grows. On the other hand, frost adheres to the refrigerant tube 2 as time elapses, and eventually the entire heat exchanger 1 is wrapped in frost.

  In this state, when the heater 5 is energized by the defrost control, the heater 5 generates heat, and the heat moves upward while spreading radially through the plate fins 4 as shown in FIG. In the process of transferring the heat upward, a portion where heat transmission is blocked by the long hole 6 and the heat shield hole 7 and a portion moving upward via the non-heat shield portion 9 are generated.

  In particular, as shown in the figure, in the case where the long hole 6 is positioned so as to overlap in the direction in which heat travels (upward), the long hole 2 becomes a heat insulating factor, and the frost around the long hole 2 becomes difficult to melt and proceeds upward. As a result, the frost around the long hole 6 is in a state where it is more difficult to melt.

  On the other hand, the non-heat-shielding part 9 in which the long holes 2 are not continuous is easy to transfer heat, and heat is quickly transmitted to the upper surface of the heat exchanger 1 and frost is easily melted.

  In the case of FIG. 2, the vicinity of the heater 5 near the refrigerant inlet (near the lowermost refrigerant tube 2) starts to quickly melt frost, and the heat of the heater 5 overlaps with the non-heat shielding part 9. It moves to the upper direction promptly, and begins to melt frost from the part close to the non-heat shielding part 9.

  Further, in the heat moving upward as shown in FIG. 3, the heat blocked by the long hole 6 or the heat blocking hole 8 starts detouring and moves to the low temperature portion while melting the frost with the detour movement. Therefore, the time required for frost melting increases in proportion to the length of the detour path.

  In order for the frost of the entire heat exchanger 1 to melt almost uniformly within a predetermined time, it is necessary to quickly transfer heat to a part that is difficult to melt.

  In the first embodiment, in the process in which the heat from the heater 5 is transmitted to the upper side of the heat exchanger 1, the heat shield part 8 shields the part where heat transfer is fast except for the peripheral part of the long hole 2. By detouring to the non-heat-shielding part 9 located below the long hole 6, the heat transfer speed is controlled so that the place where the frost is not easily melted and the place where the frost is not easily melted are eliminated. It is possible to prevent the temperature from becoming equal and to achieve a more uniform temperature.

  In other words, the heat shield 8 and the non-heat shield 9 form a heat transmission path so that the heat from the heater 5 wraps the long hole 6 as shown by the arrow in FIG. Heat transfer to the entire vessel 1 (plate fin 4) becomes possible, and the entire temperature can be made uniform. As a result, in the defrosting control controlled within a limited time, even if the defrosting control is performed when a large amount of frost is adhered, defrosting spots are not extremely generated and efficient defrosting is performed. The heat exchanger 1 having the characteristics can be provided.

  In the first embodiment, the total length (ΣL) of the dimension L of the heat shield hole 8 in the step direction of the refrigerant tube 2 is the total length (ΣL) of the dimension L of the non-heat shield portion 9 in the step direction ( With respect to Σl), it is set to about 2 times to about 4 times, and by doing so, it is possible to further improve the defrosting efficiency.

  That is, as the ratio (L / l) of the dimension L of the heat shield hole 8 and the dimension l of the non-heat shield part 9 becomes equal, the ratio of the amount of heat transferred through the non-heat shield part 9 increases. The locations where the temperature distribution spots become large and the frost has melted and the portions where the frost remains are extreme.

  On the contrary, as the ratio (L / l) of the dimension L of the heat shield hole 8 and the dimension l of the non-heat shield part 9 increases, it takes time for the heat to move upward. As a result, the heat exchanger The temperature difference between the upper side and the lower side becomes large, and it becomes difficult to eliminate frost melting spots within a predetermined time.

  In other words, if the ratio (L / l) between the dimension L of the heat shield hole 8 and the dimension l of the non-heat shield part 9 is inappropriate, it is necessary to set the defrosting operation time longer in order to eliminate defrost spots. In addition, the energy required for the defrosting operation increases and it is difficult to save energy.

  In the first embodiment, the ratio (ΣL / Σl) of the total length of the dimension L of the heat shield hole 8 and the total length of the dimension l of the non-heat shield portion 9 is about 2 to about 4 times. By defining the range, it is possible to reduce defrosting spots within a predetermined time, and as a result, efficiently perform defrosting, and in a defrosting operation within a predetermined time, a heat exchanger subjected to perforate processing with less defrosting spots Therefore, it is excellent in energy saving and can improve the performance of the heat exchanger 1.

  In the first embodiment, the dimension L of the heat shield hole 8 is made shorter than the bending pitch P of the bent tube portion of the refrigerant tube 2. As a result, the equipment for forming the plate fins 4 can be simplified.

  That is, by setting the feed pitch per mold in the molding of the plate fins 4 to be the arrangement interval T, the feed pitch becomes the same as the bending pitch P of the refrigerant tube 2.

  Therefore, the heat shield hole 8 can be formed in conjunction with the press punching operation of the long hole 6 of the plate fin 4 or the edge processing (for example, fin collar forming processing) of the long hole 6.

  In the first embodiment, in the manufacturing process of the plate fin 4, an inter-row cutter jig (not shown) that cuts the number of rows of the refrigerant tubes 2 by a predetermined number (four rows in the first embodiment). A blade jig (not shown) for forming the heat shield hole 8 is attached using the attachment site. That is, the blade jig for forming the heat shield holes 8 is attached to the positions of the first row, the second row, and the third row of the inter-row blade jig that forms four rows.

  More specifically, the heat shield hole 8 is formed in a process after the long hole 6 is formed, and the timing thereof is determined by the punching operation of the long hole 6 or the edge processing of the long hole 6 as described above. The jig operates and is formed at the same timing.

  As a result, it is possible to perform perforating by adopting a configuration in which the blade jig for forming the heat shield holes 8 is incorporated in the inter-row blade jig.

  By the way, if the dimension L of the heat shield hole 8 is made longer than the bending pitch P of the curved pipe portion of the refrigerant tube 2, the dimension L of the heat shield hole 8 becomes longer than the feed pitch (arrangement interval T). In order to cut to P or more, it is necessary to incorporate a small die set or the like capable of intermittent operation into the mold, which complicates the mold.

  However, by making the dimension L of the heat shield hole 8 shorter than the bending pitch P of the bent tube portion of the refrigerant tube 2, the mold can be simplified as described above, and the mold cost can be kept low. The cost of the vessel can be gained.

(Embodiment 2)
FIG. 4 is a cross-sectional view (corresponding to FIG. 2) of the heat exchanger according to Embodiment 2 of the present invention. FIG. 5 is a schematic diagram showing a heat transfer path in the plate fin of the heat exchanger. Here, the same constituent elements as those of the first embodiment will be described with the same reference numerals.

  In FIG. 4, the configuration different from the first embodiment is that a defrosting heater (hereinafter referred to as a heater) 12 disposed on the lower surface of the heat exchanger 1 is an air inlet side (arrow Z side) with a lot of frost formation. ) Is arranged so that the density thereof is increased, and the density on the air outlet side is reduced.

  Due to this, the heat shield holes 8 and the non-heat shield parts 9 and 13 are also different. Many heat shield holes 8 are formed and arranged on the air inlet side where the density of the heater 12 is high, and few on the air outlet side. Further, the non-heat shielding portions 9 and 13 are arranged in the same arrangement as in the first embodiment up to half of the air inlet side in FIG. 4, and the remaining half is located below the windward side in each stage of the refrigerant tube 2. The arrangement structure is such that the heat shield hole 8 is eliminated. Therefore, the heat conduction path in the leeward half of the plate fin 4 is widely formed.

  About the heat exchanger comprised as mentioned above, the defrost operation | movement at the time of being used as an evaporator of a refrigerating cycle is demonstrated.

  In general, as the cooling operation of the refrigeration cycle proceeds, more frost adheres to the air inlet side. During the defrosting operation, the air flow is stopped and the defrosting heater 4 is energized.

  In this case, defrosting is performed by the defrosting heaters 12 arranged at high density on the air inlet side where much frost is formed. As described in the first embodiment, the inlet side disperses the heat insulating effect of the long holes 2 by the arrangement configuration of the heat shield holes 8 and the non-heat shield portions 9 to equalize the heat transfer.

  On the contrary, on the air outlet side where frost formation is low, defrosting is performed by the heater 12 arranged at low density (sparsely), but since the amount of frost formation is small, the amount of heat of the heater 12 arranged at low density is sufficient. Defrosting can be performed.

  FIG. 5 shows a path of heat transfer in the plate fin of such a heat exchanger.

  As shown in FIG. 5, a large amount of heat conduction is performed on the air inlet side, and as described in the first embodiment, the heat conduction path is such that the heat from the heater 12 wraps the long hole 6 as shown by the arrow. Is formed and defrosting is performed.

  On the other hand, on the air outlet side, although the heat amount is small, a heat conduction path is formed by the heat shield holes 8 and the non-heat shield portion 13 so that heat is distributed throughout, but in particular, the non-heat shield portion 13 having a large area. Since a large amount of heat transfer is performed on the side, frost adhering to the windward side refrigerant tube 2 that hits a portion with a large amount of frost formation on the outlet side with a small amount of frost formation as a whole can be effectively melted.

  As described above, in the second embodiment, the optimum arrangement interval of the defrosting heaters 12 is set corresponding to the wind direction and the fin pitch, and the heat shielding holes 8 and the non-shielding holes in the plate fins 4 are set. By setting the heat shields 9 and 13 to the optimum quantity and arrangement, the temperature of the defrost can be further equalized, and the power consumption of the defrost heater can be reduced to contribute to energy saving.

  In the first and second embodiments, the number and arrangement of the heat shield holes and the non-heat shield portions are set differently according to the arrangement of the defrosting heater. The number and arrangement of the heat shield holes and the non-heat shield parts can be set according to the amount of frost.

  For example, in the configuration in which the first plate fin has the quantity and arrangement configuration of the first embodiment and the second plate has the quantity and arrangement configuration of the second embodiment and these are alternately arranged, the exception of the first embodiment. In the case of the frost heater arrangement, the amount of heat on the air outlet side is slightly increased (the temperature is slightly increased), and the defrosting capability of the part can be increased.

  The heat exchanger of the present invention is composed of a serpentine-like refrigerant tube and perforated plate fins, and is a heat exchanger with excellent defrosting efficiency, for cooling domestic and commercial refrigerators, showcases, etc. It can be widely applied as a vessel.

The perspective view of the heat exchanger in Embodiment 1 of this invention Sectional drawing of the heat exchanger by the AA line of FIG. Schematic diagram showing the path of heat transfer in the plate fin of the heat exchanger Sectional drawing of the heat exchanger in Embodiment 2 of this invention Schematic diagram showing the path of heat transfer in the plate fin of the heat exchanger Cross-sectional view of a conventional heat exchanger Cross section of heat exchanger showing different conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Refrigerant tube 4 Plate fin 5 Defrost pipe heater 6 Long hole 8 Heat shield hole 9 Non-heat shield part 12 Defrost heater 13 Non-heat shield part

Claims (4)

A plate in which a straight tube portion and a bent tube portion are continuously bent in a meandering manner at a predetermined pitch so that a plurality of rows and stages are formed, and a plurality of dogbone-shaped long holes are provided on the plate surface A heat exchanger comprising a plurality of plate fins spaced apart from each other and having the refrigerant tubes penetrated through the long holes, wherein the long diameter of the long holes provided in the plate fins is substantially horizontal. Further, a defrosting heater is arranged on the lower surface of the heat exchanger, and further, the plate fins are intermittently extended at a predetermined interval between the long holes arranged in the row direction. A linear heat shield hole is provided , and the heat shield hole extends below the straight pipe portion of the refrigerant tube by a predetermined dimension in the left-right direction around the straight pipe portion, and is adjacent to the heat shield hole. Between the substantially central position and between the elongated holes In addition, a non-heat-shielding portion that is not processed so as to allow heat conduction is provided, and the positional relationship between the elongated hole, the heat-shielding hole, the non-heat-shielding portion, and the defrosting heater is: A heat exchanger in which the defrosting heater is disposed so as to overlap the central portion of the long diameter of the long hole and the non-heat shielding portion on the projection surface from above .   The heat exchanger according to claim 1, wherein the total length of the heat shield holes in the step direction is set to be longer than the total length of the mutual intervals between the heat shield holes.   The heat exchanger according to claim 1 or 2, wherein a length dimension of the heat shield hole is set shorter than a bending pitch dimension of the refrigerant tube.   The heat exchanger according to any one of claims 1 to 3, wherein the defrosting heater is disposed at a substantially central position of a long diameter of a long hole provided in at least the lowermost row.

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