JPH11264632A - Heat exchanger and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy saving and low cost heat exchanger by extending a time before defrosting, and reducing the number of defrosting operations without reducing the heat exchanging performance and expanding an interval of a fin of a first line where frost is easily formed. SOLUTION: In a heat exchanger having a principal part comprising a heat transfer tubes 9, 9-1 through 9-7 arranged side by side in one line or more so as to meet nearly at right angles with an air flow, and a number of independent fins 8a through 8g integrated with the heat transfer tube and arranged side by side, on the fin 8a of a first line to the air flow or on at least a part of a surface of the heat transfer tube 9-1 of the first line where frost is easily formed is formed a coating 10b having water repellancy and icing retarding property in order to weaken the strength of frost attaching thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for cooling air in refrigerators, freezers, outdoor units for air conditioners, and the like.

[0002]

2. Description of the Related Art An evaporator of a refrigerator / refrigerator and an outdoor heat exchanger of a heat pump type air conditioner in a heating operation are provided with a heat transfer tube or a heat transfer tube arranged in at least one row arranged substantially orthogonal to an air flow. The main part is composed of a large number of fins arranged in parallel at regular intervals so that a good air flow path is formed between the fins and the refrigerant flowing inside the heat transfer tubes and between the fins and outside the heat transfer tubes. The air flowing therethrough exchanges heat (the air is cooled, and the refrigerant obtains heat). Such a heat exchanger is a condition where the temperature of the incoming air is below the freezing point,
If the temperature of the fins and heat transfer tubes is lower than the freezing point even when the temperature of the incoming air is higher than the freezing point, water droplets and ice crystals in the air will condense and adhere to the surfaces of the lower temperature fins and the heat transfer tubes. As a result, frost is generated (especially, there are many fins and heat transfer tubes in the first row of the heat exchanger for the air flow). In addition, a lot of frost is also generated at the end of the fin of the heat exchanger facing the bottom plate of the dish into which water is gradually frosted.

[0003] As the frost grows, the additional heat resistance increases due to the frost layer and the air flow path is blocked, so that the heat exchange performance gradually decreases. In order to prevent this, generally, the interval between the fins in the first row where the frost is easily formed on the heat exchanger is increased, or the frost is melted by the electric heater in the evaporator of the refrigerator and the reverse operation of the cycle in the outdoor heat exchanger of the air conditioner. Defrosting is performed when the amount of frost increases. However, if the fins in the first row where the frost is easily formed on the heat exchanger are widened, the operation does not need to be interrupted even if the fins are frosted to some extent, but the heat exchange performance is reduced,
In the defrosting method by the reverse operation of the electric heater and the cycle, although the complete defrosting can be performed, there is a problem that the normal operation is interrupted at the time of the defrosting. There is a major drawback of consuming extra power.

[0004] Instead of such a general defrosting method by melting, a method of reducing the amount of frost by forming a water-repellent coating on the surfaces of fins and heat transfer tubes has been proposed (Japanese Utility Model Laid-Open No. 3-251).
No. 693). In addition, a hard-to-ice coating that weakens the adhesion strength between ice and solids generated by icing on the surfaces of fins and heat transfer tubes (a phenomenon in which airflow containing supercooled water droplets collides with the solid surface to generate ice) is weakened. There is a method of forming and reducing the amount of frost (Trans. Of the CSME, 4, 4 (19)
76-77) pp 204-208). The former water-repellent coating is typically a simple substance such as a silicon-based or fluorine-based resin or a mixture of these resins mixed with fine particles, and the latter hard-to-ice-imparting coating is silicone rubber or grease. It is said to have good properties.

[0005] The defrosting method using these coatings has the advantage that no extra power consumption is required for defrosting and a certain effect can be obtained. However, in order to improve the defrosting effect, it is necessary to cover the entire surface of the fins and heat transfer tubes. There is a problem that the heat exchange performance is reduced due to the low temperature.

[0006]

SUMMARY OF THE INVENTION A first object of the present invention is to increase the time until defrosting without increasing the interval between the fins in the first row, which tends to form frost, and without deteriorating heat exchange performance. And reduce the number of times of defrosting.
It is a second object of the present invention to provide a heat exchanger which is inexpensive, and to provide a method for easily manufacturing such a heat exchanger.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a heat transfer tube which is arranged in at least one row arranged substantially orthogonal to an air flow, and integrated with the heat transfer tube. In the heat exchanger used in the form of cooling air, having a main part consisting of a large number of independent fins arranged at regular intervals in parallel so that a good air flow path is formed therebetween. Frost generated on at least a part of the frost-prone surface of the first row of the fins with respect to the airflow, or on at least a part of the frost-prone surface of the first row of the heat transfer tubes. A heat exchanger characterized by forming a water-repellent or hard-to-ice coating that reduces the adhesion strength of the heat exchanger.

According to a second aspect of the present invention, there is provided a heat transfer tube which is arranged in at least one row and is arranged so as to be substantially orthogonal to an air flow, and a good air flow path which is integrated with the heat transfer tube and is provided therebetween. A heat exchanger used in the form of cooling air, having a main part consisting of a large number of independent fin-type fins arranged in parallel at regular intervals so as to form Water-repellent or difficult to reduce the adhesion strength of generated frost on at least a part of the frost-prone surface of the fin or on at least a part of the frost-prone surface of the first row of heat transfer tubes. While forming an icing coating, at least a part of the surface of the fins in the second and subsequent rows that easily frosts the air flow or at least a part of the surface of the heat transfer tube that easily frosts, The surface or front of the fin A heat exchanger, characterized in that the formation of the coating amount less than the amount of the coating formed on the surface of the heat transfer tube.

According to a third aspect of the present invention, in the heat exchanger according to the second aspect, the amount of the coating formed on the fins and the like in the second and subsequent rows is the surface of the fins in the first row. And the like, characterized in that the amount of the coating is gradually reduced in order.

According to a fourth aspect of the present invention, in the heat exchanger according to any one of the first to third aspects, the edge of the fin in the first row and / or the edge of the fin in the first row are provided. The coating is formed near the heat transfer tube in contact with the fins in the first row.

According to a fifth aspect of the present invention, in the heat exchanger according to any one of the first to fourth aspects, the heat exchanger is located upstream of a line connecting the centers of the heat transfer tubes in the first row. The coating is formed on surfaces of the heat transfer tube and the fin.

According to a sixth aspect of the present invention, there is provided a heat transfer tube extending in a straight line, and a plurality of heat transfer tubes which are integrated with the heat transfer tube and are arranged in parallel at regular intervals so as to form a good air flow path therebetween. A heat exchanger precursor having fins of a side-by-side independent fin type is prepared, and a water repellent or a water repellent or the like which weakens the adhesion strength of generated frost to predetermined portions of the fins and / or the heat transfer tubes of the precursor. A method for manufacturing a heat exchanger, comprising forming a coating that is hard to adhere to ice, processing the material by bending or the like, and assembling the heat exchanger.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view illustrating a heat exchanger of the present invention. FIG. 2A shows an example in which a water-repellent or hard-to-ice coating 10 for reducing the adhesion strength of generated frost is formed on the edge of the first row of independent fins 8a. FIG. 2B is a perspective view of the first row of fins 8a and the heat transfer tube 9-1 shown in FIG. FIG. 7 shows an example of a typical refrigeration circuit. 1 is a compressor, 2 is a condenser, 3 is a dryer, 4 is a capillary tube, 5 is an evaporator, and 6 is an accumulator. Arrows indicate the flow direction of the refrigerant. The heat exchanger 7 of the present invention shown in FIG. 1 is used for the evaporator 5 shown in FIG. The heat exchanger 7 of the present invention includes heat transfer tubes 9-1, 9-2,..., 9-7 arranged in one or more rows arranged so as to be substantially orthogonal to the air flow indicated by the white arrow. , This heat transfer tube 9
-1, 9-2,..., 9-7 and a number of independent fin-type fins 8a, 8b arranged in parallel at regular intervals so that a good air flow path is formed therebetween. ...
A heat exchanger having a main part of 8 g and used in a form for cooling air. Black arrows indicate the flow direction of the refrigerant. The refrigerant entering the heat exchanger 7 from the inlet A is supplied to the heat transfer tube 9-
1, 9-2,..., 9-7, heat exchanged, and exit from the outlet B. Since the edges of all the fins 8a in the first row with respect to the airflow indicated by the white arrow are liable to frost, FIG.
As shown in (a) and (b), a water-repellent or hard-to-ice coating 10a is formed on the edge surface to reduce the adhesion strength of generated frost. The heat exchanger 7 of the present invention shown in FIG. 1 includes fins 8b, 8c, 8d facing the bottom plate of a dish (not shown) for storing water, ice, and the like when gradually defrosted.
Since a large amount of frost is also generated at the lower ends of 8e, 8f, and 8g, water-repellent or hard-to-ice coatings 10b, 10b,... 10b that reduce the adhesion strength of frost are formed.

FIG. 3 is an explanatory view showing an example in which the coating 10c is applied to other portions of the fins. FIG. 3A shows the first row of heat transfer tubes 9-1 in contact with the first row of fins 8a. It is an explanatory view showing an example in which a coating 10c is formed on a nearby fin 8a,
FIG. 3B is a perspective view of the first row of fins 8a and the heat transfer tubes 9-1 shown in FIG.

FIG. 4 is an explanatory view showing an example in which the coating 10d is applied to the fins and other portions of the heat transfer tubes. FIG. 4 (a) shows a line X connecting the centers of the heat transfer tubes 9-1 in the first row. FIG. 4B is an explanatory view showing an example in which a coating 10 d is formed on the surfaces of the heat transfer tubes 9-1 and the fins 8 a located upstream, and FIG. 4B shows the first row of fins 8 a and the heat transfer tubes 9 shown in FIG. -1 is a perspective view. White arrows indicate airflow.

FIG. 5 is a perspective view illustrating another heat exchanger 7A of the present invention. In the heat exchanger 7A of the present invention, the coating 10e is formed on most of the fins 8a in the first row and the surface of the heat transfer tubes 9-1 in the first row with respect to the air flow indicated by the white arrow. In addition, the coating 10e is also formed on the surfaces of the fins 8b, 8c, 8d in the second and subsequent rows with respect to the air flow, and also on a part of the heat transfer tubes 9-2 and 9-3 in the second and subsequent rows. Fins 8b, 8c, 8d in second and subsequent rows
The amount of the coating 10e formed on the surface of the first row of fins 8a and the like is gradually reduced gradually. After assembling the heat exchanger 7a (not shown) without the coating 10e by a conventional method, for example, the heat exchanger 7A of the present invention is placed in the upper left of the first row of fins 8a in a coating solution for forming the coating 10e. To form a coating 10e by dipping and applying the shaded portion in the figure to a line Y connecting the line M and the line N at the lower right of the fourth row of fins 8d, followed by drying. Thereby, it can be easily manufactured. In the present invention, various modifications can be made depending on how the line Y is drawn.

FIG. 6 is an explanatory view schematically showing a manufacturing process of the heat exchanger of the present invention. To manufacture the heat exchanger 7C of the present invention, first, in the step (a), a large number of independent fin-type fins 8a, 8b are arranged in parallel with the heat transfer tubes 9, 9, 9 extending linearly at regular intervals. ,..., 8 g are integrated to form a fixed heat exchanger precursor 7B. A hairpin bending portion 9a is provided between the fins 8a and 8b of the heat exchanger precursor 7B. Similarly, between the fins 8b and 8c, between the fins 8c and 8d, and the fins 8d
Fin 8e, fin 8e and fin 8f, fin 8
Hairpin bending part 9 between f and fin 8g
b, 9c, 9d, 9e and 9f are provided. Next, in step (b), predetermined heat transfer tubes 9 are welded and integrally connected at both ends of the heat exchanger precursor 7B by using U-shaped vents 9g and 9g, and the heat exchanger 7C of the present invention is provided. The coating 10a is formed at a predetermined portion of the fin 8a of the precursor 7B to be the first row of fins 8a, that is, at the edge of the fin 8a as shown in FIGS. 2 (a) and 2 (b). Then, in the step (c), the hairpin bending parts 9a and 9b are successively hairpin bent as shown in the figure, and the other hairpin bending parts 9c to 9f are successively hairpin bent and assembled. In ()), the necessary heat-exchange parts can be attached to obtain the heat exchanger 7C.

Since the present invention is not limited to the above embodiment, various modifications can be made without departing from the spirit of the present invention.

[0019]

According to the heat exchanger of the present invention, the amount of frost formed in the first row can be reduced by the coating without widening the interval between the fins in the first row, which easily causes frost, and the heat exchange performance can be reduced. Therefore, it is possible to reduce the number of times of defrosting by increasing the time until defrosting without lowering the power consumption, so that there is an energy saving effect and the cost is low. By forming the coating on at least a part of the surface of the second and subsequent rows where the fins and the heat transfer tube are easily frosted, the time until defrosting can be further increased. By gradually decreasing the amount of the coating formed on the fins and the like in the second and subsequent rows sequentially from the amount of the coating formed on the surface of the fins in the first row, the time until defrosting can be increased. With it, it becomes economical. If the coating is formed near the edge of the first row of the fins or in the vicinity where the heat transfer tubes in the first row are in contact with the fins in the first row, the coating can be easily formed and the frost removal can be performed. Time can be easily lengthened. If the coating is formed on the surfaces of the heat transfer tubes and the fins upstream of a line connecting the centers of the heat transfer tubes in the first row, the coating can be easily formed and the heat exchange performance is not reduced. The time until defrosting can be easily increased. The heat exchanger of the present invention can be easily manufactured by the manufacturing method of the present invention.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a heat exchanger of the present invention.

FIG. 2 (a) shows a water-repellent or hard-water-repellent material that reduces the adhesion strength of generated frost on the edge of the first-row independent fin type fin of the heat exchanger of the present invention shown in FIG. 1; It is explanatory drawing which shows the example which formed the coating of icing property, (b) is a perspective view of the fin of 1st row shown in (a), and a heat exchanger tube.

3 (a) is an explanatory view showing an example in which a coating is applied to another portion of the independent fin type in the first row of the heat exchanger of the present invention shown in FIG. 1; FIG. FIG. 3 is a perspective view of a first row of fins and heat transfer tubes shown in FIG.

4A is an explanatory diagram showing an example in which a coating is applied to another portion of the independent fin type in the first row of the heat exchanger of the present invention shown in FIG. 1, and FIG. FIG. 3 is a perspective view of a first row of fins and heat transfer tubes shown in FIG.

FIG. 5 is a perspective view illustrating another heat exchanger of the present invention.

FIG. 6 is an explanatory view schematically showing a manufacturing process of the heat exchanger of the present invention.

FIG. 7 is an explanatory diagram showing an example of a typical refrigeration circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Dryer 4 Capillary tube 5 Evaporator 6 Accumulator 7, 7A, 7C Heat exchanger 7B Heat exchanger precursor 8a-8g Fin 9, 9-1-9-7 Heat transfer tube 9a-8f Hairpin Bent part 9g U-shaped vent 10a, 10b, 10c, 10d, 10e Water-repellent or hard-to-ice coating X Wire connecting the center of the first row of heat transfer tubes

Claims (6)

[Claims] 1. A heat transfer tube arranged in one or more rows arranged substantially orthogonally to an air flow, and fixed intervals so as to form a good air flow path between the heat transfer tubes and the heat transfer tubes. In the heat exchanger used in the form of cooling air, which has a main portion composed of a large number of independent fin-type fins arranged in parallel with each other, the first row of the fins easily forms frost on the air flow. A water-repellent or hard-to-ice coating that weakens the adhesion strength of the generated frost is formed on at least a part of the surface, or on at least a part of the surface of the first row of the heat transfer tubes where frost is easily formed. A heat exchanger, characterized in that: 2. A heat transfer tube arranged in one or more rows arranged substantially orthogonally to an air flow, and at a fixed interval so as to be integrated with the heat transfer tube and form a good air flow path therebetween. In the heat exchanger used in the form of cooling air, which has a main portion composed of a large number of independent fin-type fins arranged in parallel with each other, the first row of the fins easily forms frost on the air flow. A water-repellent or hard-to-ice coating that reduces the adhesion strength of the generated frost is formed on at least a part of the surface, or at least a part of the surface of the first row of the heat transfer tubes that is easily frosted. In addition, the surface of the fins in the first row and the heat transfer tubes are provided on at least a part of the surface of the fins in the second and subsequent rows that are easily frosted with respect to the airflow, or at least a part of the surface of the heat transfer tube that is easily frosted. Before formed on the surface A heat exchanger wherein the coating is formed in an amount less than the amount of the coating. 3. The method according to claim 1, wherein the amount of the coating formed on the fins and the like in the second and subsequent rows is gradually reduced from the amount of the coating formed on the surface of the fins and the like in the first row. The heat exchanger according to claim 2, wherein 4. The coating according to claim 1, wherein said coating is formed at an edge portion of said first row of fins and / or in a vicinity of said first row of said heat transfer tubes contacting said first row of said fins. The heat exchanger according to any one of claims 1 to 3. 5. The coating according to claim 1, wherein the coating is formed on the surfaces of the heat transfer tubes and the fins located upstream of a line connecting the centers of the heat transfer tubes in the first row. The heat exchanger according to any one of the above. 6. A heat transfer tube which extends linearly, and a plurality of independent fins which are integrated with the heat transfer tube and which are arranged in parallel at regular intervals so as to form a good air flow path therebetween. And forming a water-repellent or hard-to-ice coating on the fins and / or the heat transfer tubes of the precursor at a predetermined position on the heat exchanger to reduce the adhesion strength of generated frost. After that, the heat exchanger is assembled by bending or the like to assemble the heat exchanger.