Refrigeration – Using electrical or magnetic effect
Reexamination Certificate
2002-08-27
2003-11-11
Doerrler, William C. (Department: 3744)
Refrigeration
Using electrical or magnetic effect
Reexamination Certificate
active
06644036
ABSTRACT:
FIELD OF APPLICATION
This invention refers to a cooling device, a method for cooling an object as well as to a cooling system which is appropriate in particular for switch cupboards.
PRIOR ART
By heat we understand an energy which exists in form of irregular atomic or molecular movements. Since on the basis of the second main thermodynamics theorem, the entropy (disorder) of a system can only increase or remain the same, for all practical transformations of an energy type into another energy type, a generation of heat does take place, whereby this heat energy is lost for the transformed useful energy. Thus, the effort is made to maintain this “waste heat” as low as possible or to avoid that it does develop at all. However, because of the physical or thermodynamic regularities, such efforts to avoid waste heat are subject to theoretical limits which cannot be exceeded. Therefore, it is unavoidable that for many practical processes waste heat develops which is to be dissipated as efficiently as possible in order to guarantee the operation of the corresponding system.
An important example for waste heat generating processes consists in electrical processes as they appear in electrotechnical installations, switchboards, electric circuits or microelectronic components. Because of friction processes of the electrons which carry the electric line, a power loss which is proportional to the resistance R and to the second power of the power loss developing as waste heat. The waste heat results, as explained in the introduction, in an increase of the kinetic energy of the atoms and molecules or in an increase of their oscillation amplitude in the solid-state grid.
For cooling objects, various methods are known which are fundamentally based on the principle that a cooler object (heat sink) is connected with a warmer object (source of heat) in such a way that, by reason of the thermodynamic tendency to take on a state of equilibrium, heat energy flows over from the source of heat to the heat sink. The transfer of heat energy can take place on the one hand by conduction of heat by which, at a microscopic level, the movement energy of the atoms or of the molecules is transferred by shock processes from one particle to the other. The rate with which heat energy is transferred by conduction of heat is proportional to the contact surface participating in the thermal conductibility &lgr; as well as to the temperature gradient (temperature difference per interval) between the source of heat and the heat sink.
A further mechanism for the transport of waste heat is the convection. Here, the waste heat is first transferred to a movable medium such as for example a cooling liquid and then carried-off with the matter of this cooling medium. The speed with which this carrying-off takes place is determined by the rate of motion of the cooling medium and can thus reach relatively high values.
Finally, a further mechanism for the dissipation of waste heat consists in the reradiation of heat energy in form of electromagnetic heat radiation. The transport speed of the heat energy is the light velocity, whereby the rate of the heat dissipation according to the Stefan Bolzmann law is proportional to the reradiating surface as well as to the fourth power of the temperature difference. This means that in particular for high temperature differences between the source of heat and the heat sink a high rate of heat dissipation can be achieved through reradiation.
For the carrying-off of waste heat as it develops, for example, for electronic components in switch cupboards, the matter is to carry off the waste heat quickly and safely away from the place of origin. Otherwise, it can come namely to a overheating and thus to a destruction of electronic components. Thus, for example, ventilation devices are used in which a strong fan blows cooling air along the surface of the components and thus ensues a quick carrying-off of heat by convection. Furthermore, it is known to apply large surface cooling bodies made of metal on components to be cooled such as, for example, microprocessors, whereby these cooling bodies should assure a quick transmission of the loss heat from the place of origin and the transfer thereof to the convection cooling. For these known solutions, it is disadvantageous that they require considerable constructional efforts with mechanically moved components which are highly subject to wear. Furthermore, the efficiency of such devices often leaves much to be desired and the cooling systems are connected with the use of substances which are harmful to the environment.
Aim, Solution, Advantage
The aim of this invention was to make available a novel cooling device which should be cheap, long wearing, as maintenance-free and simple as possible to construct without being harmful to the environment. Furthermore, the cooling device should guarantee a high efficiency for a cooling capacity also at low temperatures, preferably to −80° C., and should be adapted to different technical general conditions. Moreover, it should be possible to operate the cooling device as autonomously as possible with batteries or accumulators.
The cooling device according to the invention contains accordingly an electron emission layer which is to be applied to the object to be cooled, furthermore a suction electrode placed at a distance from the electron emission layer as well as a source of voltage, the negative pole of which is connected with the electron emission layer and its positive pole with the suction electrode.
The cooling device transports the waste heat to be carried-off with the aid of electrons. Normally, electrons are bound inside a solid by chemical bonds for certain atoms or molecules. However, for many solids such as in particular metals, by reason of quantum-mechanical level superpositions, there develop (energetic) conduction bands in which the valency electrons can move freely inside the solid. Such valency electrons also transport heat energy with their energy of movement and moreover are the carriers of the electric current conduction when an electric source of voltage is connected with the solid. The space of motion of the valency electrons is substantially limited to the inside of the solid. In the solid, there are electrons in a so-called potential well which they can only leave when they carry along a correspondingly high energy of movement which allows them to overcome the potential stage at the surface of the solid. The energy necessary for the electrons of the upper valence band of a solid for leaving the solid is designated as activation energy and constitutes a matter constant. Since, by reason of the statistical distribution of heat energy in a solid, a few electrons always have a very high energy which lies over the activation energy, a few electrons always can leave the solid. This means that such a solid is surrounded by an “electron cloud” in direct vicinity of the surface. The quantitative description of the flow of the released electrons ensues by the so-called Richardson effect equation. For temperatures around 20° C., the released electrons typically cover distances with a velocity of approximately 3500 m/s.
This invention now uses this effect of the electrons which are released for the dissipation of waste heat. In order to achieve this aim, the electron emission layer is provided which is to be connected with the object to be cooled. Eventually, the electron emission layer can also be configured as a part of the object to be cooled itself. The electron emission layer first absorbs—for example over heat conduction—waste heat from the object to be cooled. This heat energy is stored among others in the valency electrons of the electron emission layer. Thus, the fraction of the high energy electrons which overcome the activation energy and which thus can leave the electron emission layer rises. The discharged electrons carry along the inherent kinetic energy from the electron emission layer. In other words, they draw off energy from this layer. Without further measures, it would hower qu
Doerrler William C.
Friedrich Kueffner
Pfannenberg GmbH
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