JPH0271096A - Heat exchanger with fin - Google Patents

Abstract

PURPOSE:To prevent the occurrence of choking due to frosting an lowering of a draft amount, to improve heat exchange capacity, and to enable increase of a heating operation continuous time by a method wherein a heat transfer pipe is arranged downstream of an air flow from the central part of a fin, a waveform cut rise is formed in the portion, on the upper stream side of an air flow, of the fin, and a slitform cut rise is formed in the portion, on the downstream side of the air flow, of the fin. CONSTITUTION:Fins 11 are arranged in parallel at intervals of a specified distance to form a fin group 12, and an air flow passes therebetween. A heat transfer pipe 13 inserted through the fin group 12 at right angles is provided down an air flow B from the central part of the fin 11. A waveform cut rise 14 is formed in the portion, on the upper stream side of the air flow B, of the fin 11 and a slitform cut rise 15 in the portion, on the downstream side of the air flow B, of the fin. Thus, when the temperature of the air flow B is reduced and a vaporizing temperature is reduced to 0 deg.C or lower, the surface temperature, on the upper stream side of the air flow B, of the fin 11 is increased, frosting is difficult to make. Since heat transfer is promoted on the downstream side of the air flow B, frosting is easy to make, and a frost layer is formed synthetically relatively uniformly. A draft passage is ensured, and further since the waveform cut rise 14 and the slitform cut rise 15 are formed, thermal conductivity is improved and heat exchange capacity is also enhanced by means of a turbulence promoting effect and a boundary layer frontal line effect.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a finned heat exchanger used in a heat pump type air conditioner.

Conventional technology In recent years, the popularity of heat pump type air conditioners has continued to increase, and improvements are needed to prevent frost formation in the heat exchanger (evaporator) of the outdoor unit during heating operation when the outside air temperature is low. This has become an urgent task.

An example of the conventional finned heat exchanger described above will be explained below with reference to the drawings.

Figure m6 and Figure 7 show a conventional finned heat exchanger. In the figure, fins 1 are arranged in parallel at regular intervals to form a fin group 2, and 3 is a heat exchanger tube inserted into the fin group 2 at right angles.

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

The airflow flows in the direction of the figure, and when the airflow temperature decreases, the evaporation temperature becomes 0° C. or lower, and the water vapor in the airflow adheres to the fins 1- and freezes, so that WiPIJ4 is formed on the fins 1.

This frost layer 4 has a shape as shown in FIG.
The frost thickness is large at the leading edge 5 of.

This frost layer 4 grows over time, especially on the front edges 6 of the fins 1.
As the frost develops, it causes clogging between the fins 1, reducing the amount of air flow between the fins 1, and in addition, the heat exchange capacity is greatly reduced due to the insulation effect of the frost layer 4.
Defrosting is required.

Problem to be Solved by the Invention However, in the above configuration, the front edge 5 of the fi/1
Since the heat exchanger becomes clogged with M frost at an early stage, the heat exchanger cannot be downsized in order to secure the heating capacity, and there is also the problem that the duration of the heating operation is short.

The present invention addresses the above-mentioned problems and provides a finned heat exchanger that secures heat exchange capability during frosting and has a long operating time.

Means for Solving the Problems In order to solve the above problems, the heat exchanger with fins of the present invention has heat exchanger tubes arranged downstream of the center of the fins, and
The fins are provided with wave-like cut-and-raised portions on the upstream side of the airflow, and slit-like cut-and-raised portions on the downstream side of the airflow (it has a T4 configuration).

Effect The present invention has the above-described configuration, in which the heat transfer tubes are arranged on the downstream side of the airflow from the center of the fin, and the fins are provided with wavy cut and raised sections on the upstream side of the airflow, and slit-shaped sections with a higher heat transfer coefficient than the wavy sections on the downstream side of the airflow. Alternatively, since the louver-shaped cut-and-raise is provided, during frost formation, the absolute humidity difference between the airflow temperature and the saturated humid air corresponding to the fin surface temperature can be made relatively uniform, and the leading edges of the fins are not frosted. It is possible to prevent the air from concentrating and to make it relatively uniform, thereby ensuring a ventilation path.

Furthermore, since the fins are cut and raised in the form of waves and slits, a high heat transfer coefficient can be obtained due to the effect of promoting turbulence and the leading edge effect of the boundary layer.

EXAMPLE Hereinafter, as an example of the present invention, a heat exchanger with one row of fins will be described with reference to the drawings.

FIG. 1 shows a perspective view of a heat exchanger with one row of fins in an embodiment of the present invention, FIG. 2 is a sectional view of the main part of FIG. 1, and FIG. It is an A sectional view. In FIGS. 1 to 3, fins 11 are arranged in parallel at regular intervals to form a fin group 12, through which the airflow flows in the B direction.

13 is a heat exchanger tube inserted into the fin group 12 at right angles. The heat transfer tube 13 is disposed on the downstream side of the airflow B from the center of the fin 11, and has a wavy shape 14 on the upstream side of the airflow B of the fin 11 and a slit-like cut and raised portion 16 on the downstream side of the airflow B.

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

The heat transfer tube 13 is arranged on the downstream side of the airflow B from the center of the fin 11, and the waveform 14 is formed on the upstream side of the airflow B of the fin 11, and the slit-shaped cut and raised portion 16 having a higher heat transfer coefficient than the waveform 14 is formed on the downstream side of the airflow B. Therefore, under frost formation conditions when the temperature of the airflow B decreases and the evaporation temperature becomes 0°C or less, the surface temperature of the fin 11 on the upstream side of the airflow B increases, making it difficult to form frost. At the same time, heat transfer is promoted on the downstream side of the airflow B, making it easier for frost to form, and the frost layer 16 is formed relatively uniformly overall, so that even if frost forms, the ventilation path is secured. become. Further, since the fins 11 are provided with wavy shapes 14 and slit-like cut and raised portions 15, the heat transfer coefficient is improved due to the turbulent flow promotion effect and the boundary layer front effect, and the heat exchange ability is also improved.

As described above, according to this embodiment, the heat exchanger tube 13 is connected to the fin 1
The fin 1 is arranged downstream of the airflow B from the center of the fin 1.
By providing the wave-shaped 14 on the upstream side of the airflow B and the slit-like cut and raised portion 15 on the downstream side of the airflow B, the heat exchange capacity is increased, and at the time of frost formation, frost is concentrated on the front edge of the fin 11. This results in relatively uniform frost formation, secures ventilation passages, prevents clogging due to frost formation and decreases in ventilation volume, and extends the duration of heating operation.

In addition, in this embodiment, a heat exchanger with one row of fins was explained, but in a heat exchanger with two rows of fins, FIG.
As shown in Figure 6 (B-B sectional view in Figure 4), the airflow C
A similar effect can be obtained by providing a wave pattern 21 in the upstream row and a slit-like cut-and-raised portion 22 in the downstream row of the air flow C.

Effects of the Invention As described above, in the present invention, the heat transfer tube is arranged on the downstream side of the airflow from the center of the fin, and the fin is provided with a wavy cut and raised portion on the airflow upstream side and a slit-like cut and raised portion on the airflow downstream side of the fin. As a result, frost does not concentrate on the front edges of the fins, resulting in relatively uniform frost formation, securing ventilation passages, suppressing clogging caused by M frost and a decrease in ventilation volume, and reducing heat. It is possible to improve the exchange capacity and delay the heating operation duration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a finned heat exchanger according to an embodiment of the present invention, FIG. 2 is a sectional view of the main part of FIG. The figure is a sectional view of the main part of a heat exchanger with fins according to another embodiment, FIG. 5 is a sectional view taken along the line B-B in FIG. FIG. 7 is a sectional view of the main part of FIG. 6. 12... Fin group, 13... Heat exchanger tube,
14, 21...wavy, 15.22...
Slit-shaped cut and raise, B...Airflow. Name of agent: Patent attorney Shigetaka Awano and 1 other person
Figure 1 Z゛-Fin group 13-M-Irashine 枳(O? 14-Hemaro-missing 15-1 slit β゛-Air flow mozukoshi Figure 2 Figure 4 Figure 1 Zf-1-) Carbon blue large? ? -Cut and raise slit 1 size Diagram Diagram Z/

Claims (1)

[Claims] It consists of a group of fins arranged in parallel at a predetermined interval, through which the airflow flows, and a heat transfer tube inserted at right angles to the fin group, through which a heat medium flows, and the heat transfer tube is connected to the airflow downstream from the center of the fin. A heat exchanger with fins, which is arranged on the side of the fins, and has wavy cut and raised portions on the upstream side of the fins and slit-like cut portions on the downstream side of the fins.