Heat exchanger for air and freezer device

Abstract

Surface portions A with a low heat capacity and surface portions B to which frost or ice is poorly bound or attached are discretely distributed on the heat exchange surface. The surface portions A and the surface portions B have features by which, when heating the heat exchanger to which frost or ice is attached, frost or ice in contact with the surface portions A melts earlier than frost or ice in contact with the surface portions B, and at least a part of frost or ice attached to the surface portions B is made partially continuous with at least a part of frost or ice attached to the surface portions A and is thereby released from the surface portions B by its own weight. The heat exchanger having such a heat exchange surface is used as an evaporator of a refrigeration apparatus.

Description

TECHNICAL FIELD [0001] The present invention relates to an air heat exchanger and a refrigeration apparatus, in particular, to a heat exchanger with an improved surface structure. BACKGROUND ART [0002] Generally, in a refrigeration apparatus using an air heat exchanger as an evaporator, when air to be heat-exchanged with the air heat exchanger has a low temperature, and the evaporator has a low evaporation temperature, frost is produced on the heat exchange surface. When frost is produced, the air heat exchanger exhibits reduced heat exchange capacity, thereby reducing refrigerating capacity. [0003] For example, in a heat pump air conditioner as a refrigeration apparatus, when the outside air temperature is lowered during heating operation, the evaporation temperature is lowered, and an outdoor heat exchanger using an air heat exchanger is frosted. In addition, the outdoor heat exchanger has reduced evaporation performance and heating performance when frosted. Thus, defrost operatio...

AI Technical Summary

Benefits of technology

[0015] Since the air heat exchanger with such a configuration has two kinds of surface portions discretely distributed, i.e. surface portions A with a low heat capacity and surface portions B to which frost or ice is poorly bound or attached, the heat exchange surface exhibits excellent water repellency and sliding properties. For this reason, condensed water condensed on and attached to the surface of the air heat exchanger is made globular and thus is blown off easily by the pressure of wind passing through the air heat exchanger, and is supercooled and thus frozen only with difficulty. Accordingly, the growth rate of frost attached to the heat exchange surface can be reduced, and the time for refrigerating operation until the amount of frost formed requires defrosting (heating operation in the case of a heat pump air conditioner) can be extended.

[0095] In such a configuration, heating operation can be switched to defrost operation while operating the compressor continuously without cessation, and the time for defrost operation can be reduced. In addition, during defrost operation, since a large amount of the refrigerant is directly transferred to the evaporator from the compressor, heat energy accumulated on the high pressure side of the refrigerant circuit is discharged to the evaporator at a burst. Accordingly, interfacial frost or ice in contact with the surface portions A can melt in a short time, and the time for defrost operation can be reduced. In a conventional refrigeration apparatus in which frost or ice on the whole heat exchange surface has to be caused to melt, the amount of heat tends to be insufficient. In the present invention, however, it is only necessary to cause melting of frost or ice on the surface of the surface portions A (interfacial frost or ice), and thus heat energy does not lack.

Problems solved by technology

When frost is produced, the air heat exchanger exhibits reduced heat exchange capacity, thereby reducing refrigerating capacity.

In addition, the outdoor heat exchanger has reduced evaporation performance and heating performance when frosted.

Thus, defrost operation is appropriately carried out in order to remove the attached frost or ice as frozen frost (hereinafter simply referred to as frost or ice) However, when the defrost operation is carried out, the heating operation may halt or the heating capacity may be reduced, depending on the method of the defrost operation, and thus the heating comfort is disadvantageously reduced.

However, it has been found that the above conventional paints have a PTFE powder only poorly dispersed uniformly in the resin, have a poorly water-repellent area remaining on the surface, and exhibit an impaired antifrosting effect.

In addition, since it is difficult to avoid frosting thoroughly even if the antifrosting layer is formed on the heat exchange surface, defrosting is necessary for the heat exchanger.

However, the conventional paints have not been designed to reduce the time for defrost operation.

As described above, the conventional methods comprising forming an antifrosting layer on the surface have not been satisfactory.

In this method comprising applying heat energy, however, frost or ice rarely remains on the heat exchange surface, but a large amount of energy is required for melting the whole frost or ice in contact with the heat exchange surface, and the temperature becomes higher.

Thus, the method cannot be applied to an apparatus sensitive to heat.

Accordingly, the defrosting methods other than the antifrosting methods comprising forming an antifrosting layer on the surface cannot reduce the time for defrost operation of a frosted heat exchanger, either.

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