JPH11201677A - Heat exchanger with fin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a sudden decline in the amount of heat exchange at the time of frosting, and to decrease the frequency and time of defrosting operation, concerning a heat exchanger with a fin, which receives and transmits heat between the refrigerant and air of air conditioners, refrigerating machines, car equipment, etc., and fluid such as air. SOLUTION: A heat insulating cut 7 is provided between a heat transfer tube 2 and a louvered part 6 in the direction in which the heat conducting path between the heat transfer tube 2 and the louvered part 6 is lengthened. Thereby, the heat conduction to the louvered part 6' adjoining the heat transfer tube 2 with the large amount of frosting is suppressed, and the frosting to the louvered part 6' adjoining the heat transfer tube 2 is eased. The sudden decline in the amount of heat exchange at the time of heating operation can be suppressed, and also the time of heating operation can be extended by allowing relatively uniform frosting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finned heat exchanger used in an air conditioner or a refrigeration system for transferring heat between a refrigerant and a fluid such as air.

[0002]

2. Description of the Related Art In a heating operation of a heat pump air conditioner using air as a heat source, an outdoor heat exchanger functions as an evaporator, and when the ambient air temperature decreases, the refrigerant evaporation temperature decreases, and the refrigerant evaporation temperature becomes zero. Below ℃, frosting occurs. The frost increases the ventilation resistance of the heat exchanger and decreases the heating capacity. Therefore, the defrosting operation is performed periodically.

A conventional finned heat exchanger is disclosed in Japanese Patent Application Laid-Open No. 61-252494.

Hereinafter, an example of the conventional finned heat exchanger will be described with reference to the drawings.

FIG. 5 is a perspective view showing a conventional finned heat exchanger. In FIG. 5, reference numeral 1 denotes fins made of aluminum or the like. The fins are arranged in parallel at regular intervals, and 2 is a plurality of transmissions made of copper or the like, which are inserted at right angles to the fins 1 and arranged in the airflow direction. Heat tube. The heat transfer tubes 2 are connected to each other at both ends of the heat exchanger to form a refrigerant circuit.

FIG. 6 is a sectional view of a conventional finned heat exchanger. FIG. 7 is a sectional view taken along line AA of FIG. 6 and 7, reference numeral 3 denotes a fin collar, which joins the fin 1 and the heat transfer tube 2, and reference numeral 4 denotes a slit-shaped cut-and-raised portion provided so that the cut surface 4 'is perpendicular to the airflow direction. , So as to protrude above the fin surface.

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

In this heat exchanger with fins, heat is exchanged between the airflow flowing between the fins 1 and a refrigerant such as chlorofluorocarbon flowing through the heat transfer tubes 2 via the fins 1, the fin collar 3 and the heat transfer tubes 2. Done. The cut-and-raised portion 4 promotes the heat exchange between the air and the fins 1 by dividing the boundary layer of the air flowing between the fins 1, thereby promoting the heat exchange between the air and the refrigerant flowing inside the heat transfer tube 2. I was

[0009]

However, in the conventional finned heat exchanger, when used as an outdoor unit during a heating operation of a heat pump air conditioner, the finned heat exchanger functions as an evaporator, and the ambient air temperature decreases. Then, when the evaporating temperature of the refrigerant drops and the evaporating temperature of the refrigerant becomes 0 ° C. or lower, frost is formed on the surface of the fin 1 and the surface of the cut-and-raised surface 3. In particular, in the cut-and-raised portion 3 'close to the heat transfer tube 2, the heat transfer tube 2
Due to the short distance from the airflow, a large amount of frost is formed, and the airflow decreases as the ventilation resistance increases. For this reason, the amount of heat exchange falls sharply, and there has been a problem that the heating operation has to be stopped and the defrosting operation has to be performed periodically even though heat exchange is possible in other parts.

SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional problems, and to suppress a rapid decrease in the amount of heat exchange during a heating operation and extend the heating operation time.

Further, in the conventional finned heat exchanger, when the ambient air temperature decreases during the heating operation, the evaporating temperature of the refrigerant decreases. Therefore, the cut-and-raised portion 3, particularly the cut-and-raised portion 3 ′ close to the heat transfer tube 2. Since the water condenses in a concentrated manner and the condensed water is hard to cut and discharged from the three portions, there is a problem that the ventilation resistance of the heat exchanger increases and the amount of heat exchange decreases.

Another object of the present invention is to solve the conventional problems. By improving the shape of the fins, it is possible to suppress a rapid decrease in the amount of heat exchange due to frost formation and extend the heating operation time. It is to be. Further, the purpose is to promote the turbulence effect of the air flow, improve the air-side heat transfer coefficient between the air and the fins, and improve the heat exchange amount by improving the drainage of the fins.

[0013]

In order to achieve this object, the present invention provides a heat transfer tube provided between a heat transfer tube and a cut-and-raised portion provided on a surface of a fin in a stepwise direction between the heat transfer tubes. A heat insulating cut is provided in a direction in which a heat conduction path between the cut and the raised portion is lengthened.

Thus, heat conduction to the cut-and-raised portion with a large amount of frost is suppressed, the frost in the cut-and-raised portion with a large amount of frost is reduced, and the frost is relatively uniformly formed. A rapid decrease in the amount of heat exchange can be suppressed, and the heating operation time can be extended.

Further, according to the present invention, a vertical cut-and-raised portion having a cross section perpendicular to the air flow direction in a step direction between the heat transfer tubes on the surface of the fin, and a cut surface between the vertical cut-and-raised portion and the heat transfer tube is provided. A slit-like parallel cut-and-raised shape is provided which is parallel to the direction of the air flow, and has a mountain-like height whose height increases from both ends toward the center.

[0016] Thereby, heat conduction from the heat transfer tube to the vertical cut and rise near the heat transfer tube is suppressed, frost formation at the vertical cut and raise near the heat transfer tube is reduced, and frost is formed relatively uniformly. In addition, it is possible to suppress a rapid decrease in the amount of heat exchange during the heating operation and extend the heating operation time. Furthermore, the turbulence effect of air is promoted, the heat transfer coefficient on the air side between the air and the fins is improved, and when used as an evaporator during heating operation, the drainage of the fins is improved and the heat exchange amount is improved. Can be done.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention comprises fins which are arranged in parallel at regular intervals and in which a gas flows between them, and a heat transfer tube which penetrates the fins and in which a fluid flows inside the fins. Cut and raised provided in the step direction between the heat transfer tubes,
A heat insulating cut is provided between the heat transfer tube and the cut-and-raised portion in a direction in which the heat conduction path between the heat transfer tube and the cut-and-raised portion is lengthened.

Further, between the cut-and-raised portion provided in the step direction between the heat transfer tubes on the surface of the fin, and between the heat-transfer tube and the cut-and-raised portion, a heat insulating path is provided in a direction in which the heat conduction path between the heat transfer tube and the cut-and-raised portion is lengthened. By providing cuts, heat conduction from the heat transfer tube to the cut and rise with a large amount of frost is suppressed, frost formation in the cut and rise with a large amount of frost is eased, and frost is formed relatively uniformly, so that heating is performed. A rapid decrease in the amount of heat exchange during operation can be suppressed, and the heating operation time can be extended.

Further, the present invention comprises fins which are arranged in parallel at regular intervals and in which a gas flows between the fins and a heat transfer tube which penetrates the fin and in which a fluid flows inside, the heat transfer tube on the surface of the fin. The cross section is perpendicular to the airflow direction in the step direction between the vertical cut and raised, and between the vertical cut and raised and the heat transfer tube, the cut surface is parallel to the airflow direction, and the height from both ends A slit-shaped parallel cut-and-raised shape having a mountain-like shape that is higher toward the center is provided.

Then, a vertical cut-and-raised section whose cross section is perpendicular to the air flow direction in the step direction between the heat transfer tubes on the surface of the fin, and a cut surface between the vertical cut-and-raised and the heat transfer pipe is formed with respect to the air flow direction. By providing a slit-shaped parallel cut-and-raised shape that is high in height from both ends toward the center and suppresses heat conduction from the heat transfer tube to the vertical cut-and-close close to the heat transfer tube, By alleviating frost formation in the vertical cutting and raising close to the heat transfer tube and performing frost formation relatively uniformly, it is possible to suppress a rapid decrease in the amount of heat exchange during the heating operation and extend the heating operation time. Furthermore, the turbulence effect of the air is promoted, the air-side heat transfer coefficient between the air and the fins is improved, the drainage of the fins is improved, and the heat exchange amount can be improved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a finned heat exchanger according to the present invention will be described below with reference to the drawings. The same components as those in the related art are denoted by the same reference numerals, and detailed description is omitted.

(Embodiment 1) FIG. 1 is a sectional view of a finned heat exchanger according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view taken along line BB of FIG.

In FIG. 1, reference numeral 2 denotes a heat transfer tube which is the same as the conventional structure. Reference numeral 3 denotes a fin collar, which is the same as the conventional configuration.

Numerals 5 are fins arranged in parallel at regular intervals. The fins 5 are arranged so that gas flows between them and the refrigerant flowing in the heat transfer tubes 2 and the air flowing between the fins 5 exchange heat.

Reference numeral 6 denotes a cut-and-raised portion protruding from the surface of the fin 5, and 6 'denotes a vertical cut-and-raised portion adjacent to the heat transfer tube 2.

Numeral 7 denotes a notch for heat insulation, which is provided between the heat transfer tube 2 and the vertical cut and raised portion 6 'in a direction in which the heat conduction path between the vertical cut and raised portion 6' and the heat transfer tube 2 is lengthened.
This suppresses heat conduction from the heat transfer tube 2 to the vertical cut-and-raised portion 6 '.

In this embodiment, the heat transfer tube 2 is provided between the vertical cut and raised portion 6 'close to the heat transfer tube 2 and the heat transfer tube 2. It is provided in.

In this case, the heat insulating cut 7 is provided so as not to be parallel to a straight line connecting the midpoint 6 ″ of the cut-and-raised six-leg portion and the center 2 ′ of the heat transfer tube 2. In particular, it is preferable to provide such that it is orthogonal to a straight line connecting the midpoint 6 ″ of the leg portion and the center 2 ′ of the heat transfer tube 2 from the viewpoint of suppressing heat conduction.

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

In FIGS. 1 and 2, heat is exchanged between the airflow flowing between the fins 5 and a refrigerant such as chlorofluorocarbon flowing through the heat transfer tubes 2 through the fins 5, the fin collar 3, and the heat transfer tubes 2. Will be When the finned heat exchanger is used as an outdoor unit during a heating operation of a heat pump air conditioner, the finned heat exchanger functions as an evaporator.

When the temperature of the surrounding air is low, the evaporating temperature of the refrigerant decreases, and the refrigerant condenses on the surface of the fin 5 or the like. When the temperature of the refrigerant further drops to 0 ° C. or less, the condensed water drops freeze and become frost. In particular, a large amount of frost is formed on the vertical cut-and-raised portion 6 ′ that is close to the heat transfer tube 2 that is short from the heat transfer tube 2.
These condensed water droplets and frost increase the ventilation resistance of the heat exchanger with fins and decrease the heating capacity.

However, since the heat insulating notch 7 is provided between the vertical cut-and-raised portion 6 'and the heat transfer tube 2, the heat transmitted from the vertical cut-and-raised portion 6' to the heat transfer tube 2 bypasses the heat insulating notch 7. Thus, the heat conduction from the vertical cut-and-raised portion 6 ′ to the heat transfer tube 2 is suppressed, and the vertical cut-and-raised portion 6 ′ is formed.
The amount of frost can be reduced, and frost can be formed relatively uniformly. As a result, it is possible to suppress a rapid decrease in the amount of heat exchange during the heating operation and extend the heating operation time.

(Embodiment 2) FIG. 3 is a sectional view of a finned heat exchanger according to Embodiment 2 of the present invention, and FIG. 4 is a sectional view taken along line CC of FIG.

In FIG. 3, reference numeral 2 denotes a heat transfer tube which is the same as the conventional structure. Reference numeral 3 denotes a fin collar, which is the same as the conventional configuration.

Numerals 8 are fins arranged in parallel at regular intervals. The fins 8 are arranged so that gas flows between them and the refrigerant flowing in the heat transfer tube 2 and the air flowing between the fins 8 exchange heat.

Reference numeral 9 denotes a vertical cut-and-raised protruding from the surface of the fin 8, and 9 'denotes a vertical cut-and-raised proximate to the heat transfer tube 2.

Reference numeral 10 denotes a slit-shaped parallel cut-and-raised shape in which the cut surface 10 ′ is parallel to the direction of the air flow, and the height is higher from both ends toward the center, and has a mountain shape. It is provided between the cut-and-raised portion 9 ′ and the heat transfer tube 2 in parallel to the airflow direction.

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

3 and 4, heat is exchanged between the airflow flowing between the fins 8 and a refrigerant such as chlorofluorocarbon flowing through the heat transfer tubes 2 through the fins 8, the fin collar 3, and the heat transfer tubes 2. Will be When the finned heat exchanger is used as an outdoor unit during a heating operation of a heat pump air conditioner, the finned heat exchanger functions as an evaporator.

At this time, when the ambient air temperature is low,
The evaporation temperature of the refrigerant decreases, and the refrigerant condenses on the surface of the fin 8 or the like.
When the temperature of the refrigerant further drops to 0 ° C. or less, the condensed water drops freeze and become frost. In particular, a large amount of frost is formed on the vertical cut-and-raised portions 9 ′ that are close to the heat transfer tube 2 that is short from the heat transfer tube 2. These condensed water droplets and frost increase the ventilation resistance of the heat exchanger with fins and decrease the heating capacity.

However, the cut surface 1 of the parallel cut-and-raised 10
Since 0 ′ is generated parallel to the airflow direction, the airflow collides with the end face 10 ″ of the parallel cut-and-raised 10 and the turbulence effect of the air is promoted, and the air between the fin 8 and the air is increased. The side heat transfer coefficient is improved, and the amount of heat exchange can be improved.

Further, since the height of the parallel cut-and-raised portion 10 is high from both ends of the cut-and-raised portion toward the center, and the cut surface 10 'is arranged parallel to the airflow direction, The water droplet condensed on the cut and raised 10
The air is easily discharged from the cut-and-raised portion by the air current, and a reduction in the heating capacity can be suppressed.

Further, the parallel cut-and-raised 10 is a heat transfer tube 2
Is provided between the vertical cut-and-raised portion 9 ′ and the heat transfer tube 2, so that heat conduction from the vertical cut-and-raised portion 9 ′ to the heat transfer tube 2 is suppressed, and the amount of frost formed on the vertical cut-and-raised portion 9 ′ is reduced. ,
Frost can be formed relatively uniformly. As a result, it is possible to suppress a rapid decrease in the amount of heat exchange during the heating operation and extend the heating operation time.

[0044]

As described above, according to the present invention, fins are arranged in parallel at regular intervals and gas flows between them.
A heat transfer tube that penetrates the fins and through which the fluid flows, and between the heat transfer tube and the cut-and-raised portion provided in the step direction between the heat transfer tubes on the surface of the fin; The heat insulating cut is provided in the direction in which the heat conduction path is extended, so that a rapid decrease in the amount of heat exchange during the heating operation can be suppressed and the heating operation time can be extended.

Further, the fins are arranged in parallel at a predetermined interval, and include fins through which gas flows, and heat transfer tubes through which the fluid flows, and a step between the heat transfer tubes on the surface of the fins. In the direction, the cross section is perpendicular to the airflow direction,
The cut surface is parallel to the air flow direction, and the height is increased from both ends toward the center and a mountain-shaped slit-shaped parallel cut-and-raised is provided, so that the amount of heat exchange during heating operation suddenly decreases. In addition to suppressing, the heating operation time can be extended. Further, the amount of heat exchange during the heating operation can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a finned heat exchanger according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line BB in FIG.

FIG. 3 is a cross-sectional view of a finned heat exchanger according to Embodiment 2 of the present invention.

FIG. 4 is a sectional view taken along the line CC in FIG. 3;

FIG. 5 is a perspective view of a conventional finned heat exchanger.

FIG. 6 is a cross-sectional view of a conventional finned heat exchanger.

7 is a sectional view taken along the line AA in FIG. 6;

[Explanation of symbols]

 2 Heat transfer tube 5, 8 Fin 6 Cut and raised 7 Insulated cut 9 Vertical cut and raised 9 ', 10' Cut surface 10 Parallel cut and raised

Claims (2)

[Claims] 1. A fin which is arranged in parallel at a predetermined interval and in which gas flows between each other, and a heat transfer tube which penetrates the fin and in which a fluid flows inside, the heat transfer tube on the surface of the fin. Heat exchange with fins provided with a notch for heat insulation provided between the cut-and-raised portion provided in the step direction between the heat transfer tube and the cut-and-raised portion in a direction in which a heat conduction path between the heat transfer tube and the cut-and-raised portion is lengthened. vessel. 2. A fin, which is arranged in parallel at regular intervals and in which a gas flows between the fins, and a heat transfer tube which penetrates the fin and in which a fluid flows inside, the heat transfer tubes on the surface of the fins. A vertical cut and rise whose cross section is perpendicular to the airflow direction in the step direction between, and between the vertical cut and raise and the heat transfer tube, the cut surface is parallel to the airflow direction, and the height is both ends. A heat exchanger with fins provided with slit-shaped parallel cut-and-raised portions that have a high mountain shape from the center toward the center.