Heat exchanger

Abstract

A heat exchanger (1) includes: a heat sink (3) which is in contact with a heating element (2); and an electron emitting element (4) which is provided so as to be separated from the heat sink (3) by a space and which provides electrons to the heat sink (3) via air in the space. The electron emitting element (4) includes: an electrode substrate (7); a thin-film electrode (9); a power supply (10) which applies a voltage between the electrode substrate (7) and the thin-film electrode (8); and an electron acceleration layer (8) which accelerates the electrons inside itself in response to the voltage applied by the power supply (10) so that the electrons are emitted from the thin-film electrode (9). The electron acceleration layer (8) is made at least partially of an insulating material. As a result, the heat exchanger (1) has a heat exchange capability which can be maintained and improved independently of a structure in which electric field concentration tends to occur.

Description

TECHNICAL FIELD[0001]The present invention relates to a heat exchanger.BACKGROUND ART[0002]Conventionally, a rotary-blade airflow generator (hereinafter referred to as “fan”) has normally been used as a means of cooling a heating element. However, the use of a fan for such cooling causes a problem of large noise made by the fan in operation. To solve this problem, cooling with use of an ionic wind caused by a corona discharge has been devised to replace the cooling with the use of a fan (see, for example, Patent Literatures 1 and 2). The use of an ionic wind eliminates wind noise peculiar to operation of a fan, and thus reduces noise. Further, the following is known (see Non Patent Literature 1): A heat source (heating element) is cooled more effectively when air blown by a fan is used in combination with an ionic wind than when air blown by a fan is solely used. Non Patent Literature 2 describes a condition necessary for a corona discharge to be stably generated.[0003]The following...

AI Technical Summary

Benefits of technology

[0020]The heat exchanger of the present invention includes the electron emitting element provided so as to be separated from the electrically conductive contact member which is in contact with the target of heat exchange. Further, the electron emitting element includes: the electrode substrate; the thin-film electrode; the first voltage applying means for applying the voltage between the electrode substrate and the thin-film electrode; and the electron acceleration layer which accelerates the electron inside itself in response to the voltage from the first voltage applying means so that the electron is emitted from the thin-film electrode. In addition, the electron acceleration layer is formed at least partially with an insulating material. This arrangement allows for provision of the electron emitting element which can emit electrons in an internal electric field. In other words, the electron emitting element provides electrons to the contact member via the air present in the space between the electron emitting element and the contact member. These electrons collide with air molecules present in the space. This collision ionizes the air molecules. Further, these ionized air molecules move along an electric field, and thus generate an ionic wind. The ions then arrive at the contact member. This stirs air molecules which are present along the surface of the heat source.

[0021]As described above, according to the above arrangement, the electron emitting element which can emit electrons in an internal electric field is provided, instead of a conventional wire electric discharge element, so as to be separated from the contact member. As a result of this, even with a structure in which electric field concentration tends to occur in the vicinity of the contact member, the electron emitting element can stably provide electrons into the atmosphere, and thus generate an ionic wind. In addition, it is possible to stably provide an ionic wind even if the contact member has a complex shape. In other words, the heat exchanger of the present invention generates an ionic wind not with use of a conventional wire electric discharge element which causes a corona discharge, but with use of the electron emitting element which can emit electrons in an internal electric field. Thus, it is not necessary to reduce the number of discharge sections for device downsizing, unlike in conventional ionic-wind cooling devices. Furthermore, it is not necessary to reduce the distance between electrodes for wire electric discharge. Thus, the above arrangement prevents problems associated with conventional ionic-wind cooling devices which cause a corona discharge, the problems including a problem concerned with a distance between electrodes for wire electric discharge. In a case where, for example, the contact member is a heat sink, the above arrangement, in view of device downsizing, allows a device having a certain size to include more fins than a conventional ionic wind generator. This consequently improves a heat exchange capability.

[0022]As described above, the above arrangement allows for provision of the heat exchanger having a heat exchange capability which can be maintained and improved independently of a structure in which electric field concentration tends to occur.

Problems solved by technology

However, the wire electric discharge (corona discharge) performed by the ionic-wind cooling device disclosed in Patent Literature 3 poses a problem described below.

Thus, a cooling device using a corona discharge involves a risk of a high voltage.

In addition, the large interelectrode distance problematically results in a large-size cooling device.

This results in a local temperature rise.

This temperature rise then leads to breaking of a wire electrode and / or damage to a heat source.

This problematically prevents maintenance and improvement of a cooling capability of the cooling device.

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