JPS61153498A - Finned heat exchanger - Google Patents

Abstract

PURPOSE:To uniform the layer of frost between fins by a method wherein the surface of respective fins is formed into the shape of waveform and the width of waveform is constituted so as to be increased stepwisely as the fin approaches the outflow direction of airflow. CONSTITUTION:In the inflow part of airflow of the corrugated fin 4, the height H of the waveform of the corrugated fin 4 is low and the air stream is not disturbed so easily, therefore, an absolute humidity difference between ambient air and saturated humid air becomes small. As a result, the thickness of the layer 3 of frost at the inflow part of air of the corrugated fin 4 becomes thin. Since the height H between the crest and trough of the corrugated fin 4 is increased as the position of the fin approaches to the outflow direction of air, the disturbance of air is generated gradually and heat exchange is effected between cooled and dehumidified air whereby the layer 3 of frost is formed. Accordingly, the frost 3 on the surface of the corrugated fin 4 becomes the layer of frost having an uniform thickness and air ventilating path may be secured widely, therefore, the deterioration of heat exchanging amount may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heat exchanger with fins, such as a heat pump type air conditioner, which uses air as a heat source.

BACKGROUND OF THE INVENTION Conventionally, heat exchangers used in air conditioners, etc. Figure (a),
A heat exchanger with fins having a configuration as shown in (b) is known.

That is, a finned heat exchanger is constructed by arranging a large number of fins 1 in parallel at predetermined intervals to form a fin group, and by intersecting the heat transfer tubes 2 perpendicularly to the fin group in multiple stages.

Further, each of the fins 1 has a wave width H in order to improve the heat transfer effect between the fins 1 and a gaseous heat exchange fluid such as air.
The fin 1 has a wave shape with a constant value.

The operation when such a finned heat exchanger is used during heating operation of a heat pump type air conditioner or the like that uses air as a heat source will be described.

The outdoor finned heat exchanger functions as an evaporator, and when the ambient air temperature decreases, the evaporation temperature becomes 0° C. or lower, and water vapor in the air adheres to the fin surface as frost 3 to form a frost layer.

When the space between the fins 1 is blocked by frost a, the fins 1
Since air cannot flow in between the fins, the heat exchange capacity is reduced, and the heating capacity is reduced. Therefore, a defrosting operation is performed to melt the frost 3 adhering to the surface of the fins 1.

Problems to be Solved by the Invention However, when the finned heat exchanger having the above configuration is used as an outdoor heat exchanger for a heat pump type air conditioner, etc., as shown in FIG. 2(b), Since the turbulence of the mainstream occurs from the fin inlet, more frost layers 3 are formed at the air inlet of the fins 1, and the space between the fins 1 is closed in a short time. As a result, the amount of passing air was reduced, and the amount of heat exchanged was significantly reduced in a short period of time.

Therefore, heating operation must be interrupted and defrosting operation must be performed frequently, which impairs the comfort during heating and also has poor energy efficiency.

The present invention solves the above-mentioned conventional drawbacks, suppresses the space obstruction of frost between the fins during frost formation, extends the time until the space between the fins becomes blocked by frost, and improves comfort during heating. The present invention provides an excellent outdoor heat exchanger that improves energy efficiency.

Means for Solving the Problems The heat exchanger with fins of the present invention is arranged in parallel at regular intervals, and the surface of each fin in a group of fins through which an air flow flows is formed into a wave shape. The width H is configured to increase stepwise in the direction of the outflow of the airflow.

Effect: With the above-described configuration, the airflow is gradually disturbed in the outflow direction of the airflow, and heat exchange is promoted. Therefore, the frost layer between the fins can be made uniform, and the space between the fins can be prevented from being blocked by frost. It is possible to extend the time required for defrosting, reduce the number of defrosting operations, improve comfort during heating, and improve energy efficiency.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS.
).

FIG. 1 (,) is a plan view of the fin shape of the finned heat exchanger of the present invention, which includes corrugated fins 4 formed in a wave shape on the fin surface, and a large number of heat transfer tubes 2 through which a refrigerant flows. A finned heat exchanger is constructed. Note that the arrow indicates the direction of air inflow.

FIG. 1(B) is a detailed sectional view of the air inlet end of the corrugated fin 4 taken along line AA' in FIG. 1(,).

In both figures, the wave width H of the corrugated fins 4 is configured to gradually increase in the direction of the outflow of the airflow.

By adopting the above configuration, the wave width H of the waveform fins 4 is low at the airflow inflow part of the waveform fins 4, so airflow turbulence occurs and heat exchange with the surrounding air, which is related to the amount of frost formation The absolute humidity difference in saturated humid air corresponding to the temperature of the heat transfer surface of the device becomes smaller. As a result, the thickness of the frost layer 3 at the air inflow portion of the corrugated fins 4 becomes thinner.

Then, the air that has been gradually cooled and dehumidified gradually becomes turbulent because the heights H of the peaks and valleys of the corrugated fins 4 are gradually increased with respect to the outflow direction of the air. ,cooling,
Heat is exchanged with the dehumidified air, and a frost layer 3 is formed.

Therefore, the frost layer [3 is uniformly thick] is formed on the four surfaces of the corrugated fins, and even if the same amount of frost layer is formed as before, the space between the fins will not be blocked, ensuring a wide ventilation path. I can do things. Therefore, there is little increase in ventilation resistance, only a slight decrease in the amount of passing air, and less deterioration of the heat exchanger, reducing the number of defrosting operations, improving comfort during heating, and improving energy efficiency. can be significantly improved.

Effects of the Invention As is clear from the above explanation, the finned heat exchanger of the present invention is configured such that the wave width H of each fin in the fin group increases in stages (as the wave width H increases in the air flow direction). At the airflow inflow part of It is possible to secure a wide ventilation path without causing any problems.
There is little increase in ventilation resistance and only a slight decrease in passing air volume.
In practical terms, it reduces the drop in heat exchange volume, reduces the number of defrosting operations, improves comfort during heating, and significantly improves energy efficiency.
It has great effects.

[Brief explanation of the drawing]

Fig. 1(,) is a plan view of the fin shape of a finned heat exchanger showing an embodiment of the present invention, and Fig. 1(b) is an air inflow end taken along line A-A' in Fig. 1(,). Figure 2 (,) is a detailed sectional view of the fin shape of a conventional heat exchanger with fins,
FIG. 2(b) is a detailed cross-sectional view of the air inflow end taken along the line B-B' in FIG. 2(,). 2... Heat exchanger tube, 3... Frost, 4...
・Wave-shaped fin, H...Wave width. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure? −・ Maro H3,9 skin width to Yi Yunshi? bJ/l

Claims (1)

[Claims] A finned heat exchanger consists of a fin group consisting of a large number of fins arranged in parallel at regular intervals, through which air flows, and a group of heat transfer tubes inserted at right angles to the fin group, through which fluid flows. The heat exchanger with fins further has a wavy shape formed on the surface of the fin, and the wave width H of each waveform is increased in stages in the outflow direction of the airflow.