Electric heating – Inductive heating – With heat exchange
Reexamination Certificate
1998-02-19
2001-10-02
Leung, Philip H. (Department: 3742)
Electric heating
Inductive heating
With heat exchange
C219S630000, C219S634000, C219S672000, C219S674000
Reexamination Certificate
active
06297483
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heating apparatus for heating a gas, a liquid, a solid and the like.
2. Description of the Related Art
Conventionally, heating systems for heating by gas, such as instantaneous water heaters, have been used in order to rapidly raise the temperature of a liquid. In order to heat a solid, metal sheathed tubular elements have been used, for example.
When water is rapidly heated by a conventional instantaneous water heater, the temperature of a heat transfer surface to water exceeds a boiling point due to an excessive calory density. Thus, local boiling is easy to generate, which results in poor safety.
In order to avoid local boiling, a heat exchange area needs to be increased, but an increased heat exchange area enlarges the heating apparatus because of the structure of the combustion section.
Moreover, heating by gas, which is performed from outside a pipe through which water flows, has a low thermal efficiency.
In the case of an electric water heater, a local abnormal temperature rise is easily generated due to an excessive electricity density. This type of water heater also has problems of a low level of safety at the time of and disconnection of the heater. Accordingly, the electric water heater is not suitable to boil water to a temperature close to a boiling point.
In the case where a solid having poor thermal transfer is heated by metal sheathed tubular elements, the temperature is excessively raised only in a portion opposed to the metal sheathed tubular elements, which acts as a heat source.
In the case where the heat exchange surface is increased in order to avoid generation of local heating, the heating apparatus is enlarged and also the heat capacity of the heater is increased. Thus, the temperature response is deteriorated.
In a heating apparatus for heating and thus recovering an adsorbent such as active carbon or zeolite, it is necessary to increase the heat exchange area so as to increase the surface to contact the adsorbent. When a conventional electric heater is used, the heating apparatus is enlarged and the recovering efficiency is low due to the non-uniform temperature of the electric heater.
In a conventional heating apparatus for heating water to generator vapor, the rise is slow and the energy efficiency is low since the water in the reservoir is heated. In a structure in which vapor is instantaneously generated, the heat exchange area needs to be increased, and thus the heating apparatus is enlarged.
When a conventional electric heater is used in a heating apparatus for purifying the air using a catalyst, the effective reaction area cannot be increased due to a limit in the thermal transfer in the carrier (catalyst). Accordingly, the purifying capability is low.
Furthermore, a conventional heating apparatus requires a thermostat and a temperature fuse to be installed in the vicinity of the heat source, resulting in a complicated structure of the heating apparatus.
A conventional electric water heater further has the problem in that scale is accumulated on the surface of the heater and thus abnormal heating disconnects a part of the electric heater to which the scale adheres.
SUMMARY OF THE INVENTION
A heating apparatus according to the present invention includes a heating element having a conductor, at least a part of which is an electrically closed circuit along which an eddy current flows; a container for accommodating the heating element; a magnetic field induction section for induction-heating the heating element; and a high frequency power supply device for supplying high frequency power to the magnetic field induction section. The heating element is induction-heated by an AC magnetic field generated by the magnetic field induction section.
In one embodiment of the invention, the conductor of the heating element has a total thickness which is suitable for generating an electromotive force to cause the eddy current to flow along the closed circuit. The total thickness will be defined later.
In one embodiment of the invention, the conductor of the heating element is wound in one of a circumferential state and a spiral state.
In one embodiment of the invention, the heating element includes a plurality of non-magnetic metal bodies arranged concentrically.
In one embodiment of the invention, the heating element includes at least one non-magnetic metal body and at least one magnetic metal body provided inside the at least one non-magnetic metal body, the metal bodies being concentrically provided.
In one embodiment of the invention, the heating apparatus includes a plurality of heating elements arranged in the container.
In one embodiment of the invention, the conductor of the heating element is processed to be wave-like.
In one embodiment of the invention, the heating apparatus further includes an adsorbent provided in a gap between overlapping parts of the conductor.
In one embodiment of the invention, the heating apparatus further includes a moisture-adsorbing material provided in a gap between overlapping parts of the conductor.
In one embodiment of the invention, the heating apparatus further includes a material having a moisture maintenance capability provided in a gap between overlapping parts of the conductor.
In one embodiment of the invention, the heating apparatus further includes a catalyst on the conductor.
In one embodiment of the invention, the conductor has a hole.
In one embodiment of the invention, the conductor has a wing in the vicinity of the hole for transferring a fluid from one surface of the conductor to another surface of the conductor.
In one embodiment of the invention, the conductor is porous.
In one embodiment of the invention, the container allows a fluid to pass through a part of the container involved in heat exchange.
In one embodiment of the invention, the heating element has a closed circuit which is disconnected when the heating element reaches a prescribed temperature.
In one embodiment of the invention, the conductor is formed of a material having a thermal dependent resistance.
In one embodiment of the invention, the conductor is formed of a material memorizing a prescribed shape and recoverable to the prescribed shape in accordance with a temperature.
In one embodiment of the invention, the heating apparatus further includes a spring for restricting a shape change of the conductor.
In one embodiment of the invention, the magnetic field induction section includes a coil provided on an outer surface of the container. The coil has a greater number of windings per unit length in an area in the vicinity of an end of the coil than an area at a center of the coil.
In one embodiment of the invention, the magnetic field induction section includes a coil having two ends provided on an outer surface of the container. The coil has a greater number of windings per unit length in an area in the vicinity of one end of the coil than in an area in the vicinity of another end of the coil.
Thus, the invention described herein makes possible the advantage of providing a heating apparatus having satisfactory controllability and a sufficiently high thermal efficiency using a heating element having a sufficiently large heat exchange area and performing uniform heating.
This and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
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European Search Report for corresponding Europe
Kondoh Shinji
Obata Tetsuo
Omori Hideki
Sadahira Masafumi
Uetani Youji
Leung Philip H.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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