CN112902491A

CN112902491A - Method and device for refrigeration by photo-induced thermoelectron and photon cooperative emission

Info

Publication number: CN112902491A
Application number: CN202110074275.XA
Authority: CN
Inventors: 郑光华; 王关晴; 陈翔翔; 黄雪峰; 徐江荣
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2021-01-20
Filing date: 2021-01-20
Publication date: 2021-06-04
Anticipated expiration: 2041-01-20
Also published as: CN112902491B

Abstract

The invention discloses a method and a device for refrigeration by photo-induced thermoelectron and photon cooperative emission. The cathode body absorbs light source photons and heat energy of the heat source, and internal valence band bound electrons are transited to a conduction band to become hot electrons. Part of the hot electrons carry energy to be emitted to vacuum and conducted to the anode body under the action of the electric field force provided by the voltage source; partial hot electrons generate photons through the recombination action with valence band holes, the photons carry energy to leave the cathode body and collide with alkali metal vapor to generate plasma, the negative space charge effect is weakened, and the thermionic emission is enhanced. The cathode body absorbs the energy of the heat source to reduce the temperature thereof by the mode of the cooperative emission of the thermal electrons and the photons, thereby realizing refrigeration. The invention fully utilizes two energy transfer working media of electrons and photons, has better heat exchange characteristic, enables the usable temperature of the refrigerating device to be lower, has wider application range and has good economic effect and social benefit.

Description

Method and device for refrigeration by photo-induced thermoelectron and photon cooperative emission

Technical Field

The invention relates to the technical field of solid refrigeration, in particular to a hot electron refrigeration method and a hot electron refrigeration device.

Background

The traditional vapor compression refrigeration technology is realized by circulating absorption and release of refrigeration working media, and has certain defects of complicated structure, high cost and great environmental hazard. The novel solid-state refrigeration technology adopts electrons as working media, realizes refrigeration through entropy change of the electrons, has the characteristics of simple and reliable mechanism and environmental protection, and specifically comprises the modes of elastic thermal refrigeration, thermoelectric refrigeration, thermomagnetic refrigeration, thermionic refrigeration and the like. Because the hot end and the cold end of the first three refrigeration modes are closely connected, the refrigeration performance of the refrigeration modes is severely limited by the thermal conductivity and the electric conductivity of the material. Low thermal conductivity and high electrical conductivity are advantageous for producing excellent refrigeration effect, however, materials with high thermal conductivity are necessarily high electrical conductivity.

The hot end and the cold end of the thermal electron refrigeration are isolated in vacuum, and the thermal electron at the cold end is emitted and transported to the hot end under the action of an external electric field, so that the refrigeration is realized. Compared with a refrigeration technology without vacuum isolation, the thermoelectron refrigeration is not limited by lattice heat conduction, electrons do not scatter in movement between electrodes, ohmic resistance does not exist, and the thermoelectron refrigeration has larger temperature difference between a hot end and a cold end. However, the emission performance of hot electrons depends on the work function of the surface of the material, and the smaller the work function of the surface, the better the emission performance of hot electrons. Conventional cesium atom deposition can lower the electrode surface work function to about 1.6eV, however this is not sufficient to achieve efficient thermionic cooling. The work function of the surface of the material can be effectively reduced through the design of the nano-space structure, but the design has high requirements on the polar space control and the manufacturing process, and the industrialization promotion of the thermal electron refrigeration technology is hindered.

Disclosure of Invention

The invention provides a method and a device for refrigeration by photo-induced thermoelectrons and photon cooperative emission, aiming at overcoming the influence of low thermionic emission efficiency on the thermionic refrigeration performance. The method can improve the emission characteristic of the thermoelectrons, and simultaneously couple the energy carrying characteristic of photon radiation to enhance the overall performance of thermoelectron refrigeration.

A method for refrigeration by photo-induced thermal electron and photon cooperative emission is disclosed, which is characterized in that a cathode body absorbs light source photons and heat energy of a heat source, and internal valence band bound electrons are transited to a conduction band to become thermal electrons; part of the thermal electrons carry energy to be emitted to vacuum and conducted to the anode body under the action of an electric field; partial hot electrons generate photons through the recombination action with valence band holes, the photons carry energy to leave the cathode body and collide with alkali metal vapor to generate plasma, the negative space charge effect is weakened, and the emission of the hot electrons is enhanced. The cathode body absorbs the energy of the heat source to reduce the temperature thereof by the mode of the cooperative emission of the thermal electrons and the photons, so as to realize refrigeration.

Preferably, the light emitting source can be a laser diode or a light emitting diode, and is powered by a voltage source to generate photons; or a natural light source.

Preferably, the cathode body comprises a cathode active layer, a cathode conductive layer, a cathode isolation layer and a cathode substrate; the cathode substrate is provided with a cathode isolation layer, a cathode conducting layer is arranged on the cathode isolation layer, and a cathode active layer is arranged on the cathode conducting layer; the cathode active layer is used for reducing the potential barrier of electron emission. The cathode conductive layer is used for absorbing photons of the luminous source and generating free electrons, and meanwhile, connection with an external circuit is achieved. The cathode isolating layer is used for obstructing the connection of the cathode conducting layer and the cathode substrate.

Preferably, the anode body includes a glass substrate, an anode conductive layer, and an insulator. The surface of the glass substrate is provided with an anode and an anode conducting layer, wherein the anode conducting layer is arranged on two sides of the anode, and the insulator is arranged on the anode conducting layer; the glass substrate is used for supporting the anode film layer, and the anode conducting layer is connected with the anode and an external circuit; the anode is made of a light-transmitting conductive material.

Preferably, the insulator is an absolute low thermal conductivity material and is used for isolating the cathode body and the anode body, regulating and controlling the distance between the cathode and the anode and manufacturing a vacuum environment beneficial to electron transportation.

A photo-induced thermal electron and photon cooperative emission refrigerating device comprises a cathode body, an anode body, an insulator, a voltage source and a luminous source. The cathode body absorbs light source photons and heat energy of a heat source to generate hot electrons, part of the hot electrons are emitted to the anode body under the action of an electric field, part of the electrons are emitted to the anode body in a form of energy carried by the photons through a composite effect, and collide with alkali metal vapor (7) to generate plasma and enhance the emission of the hot electrons so as to realize refrigeration, and the insulator is arranged between the cathode body and the anode body and used for isolating the cathode body and the anode body. The alkali metal vapor is cesium or rubidium metal vapor.

Preferably, the cathode body is a cathode isolation layer deposited on a cathode substrate, a cathode conducting layer grows on the cathode isolation layer, and a cathode active layer is coated on the upper surface of the cathode conducting layer; the cathode substrate is a silicon cathode substrate, the cathode isolation layer is a silicon dioxide insulating layer, the cathode conducting layer is a heavily doped high-conductivity monocrystalline silicon layer, and the cathode active layer is a barium active layer.

Preferably, the anode body is formed by sputtering an anode on a glass substrate and depositing an anode conductive layer on the edge; the anode is an indium tin oxide transparent conductive layer, and the anode conductive layer is a high-conductivity silicon layer.

Preferably, the insulator is formed by growing a silicon dioxide layer on the anode conducting layer, realizing sealing with the cathode layer in the cathode body by adopting an anode bonding mode, and regulating the thickness of the silicon dioxide layer so that the distance between the cathode and the anode is kept between 0.1 and 1 mm.

Preferably, the light-emitting source is an active light-emitting device or a passive light source; the heat source generates heat electronic devices, refrigerator storerooms or building houses.

Compared with the prior art, the invention has the following advantages:

1. the energy from the cold end to the hot end is transferred through two working media, namely electrons and photons, and compared with the traditional hot electron refrigeration mode, the cold-end and hot-end heat exchange device has better heat exchange characteristics.

2. Due to the excitation effect of the front-stage photoproduction electrons, the temperature required by the electrons to be heated to vacuum is lower, and the same amount of thermionic emission number can be generated at lower temperature, so that the usable temperature of the refrigerating device is lower.

3. The distance between the hot end and the cold end of the photoinduced thermionic refrigerating device is in a millimeter level, so that the photoinduced thermionic refrigerating device is easier to package and integrate and is beneficial to large-scale application.

Drawings

FIG. 1 is a schematic diagram of a photo-thermionic and photon co-emission refrigeration system.

FIG. 2 is a structural diagram of a device for cooling by photo-induced thermoelectron and photon cooperative emission.

Fig. 3 is a schematic diagram of a photo-thermal electron and photon cooperative emission system suitable for refrigeration in a refrigerator.

Fig. 4 is a schematic diagram of a photo-thermionic and photon cooperative emission system suitable for use in building refrigeration.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings in combination with the specific embodiments.

The invention combines the thermoelectron refrigeration technology, the photoinduced thermoelectron emission technology and the photon emission refrigeration technology, avoids the processing and manufacturing of the material nanometer inter-polar distance, the thermalization temperature required by the thermoelectron emission into vacuum is lower, the heat at the cold end is simultaneously transported to the hot end by electrons and photons, the service temperature of the thermoelectron refrigeration is lower, and the thermoelectron refrigeration performance is improved.

Example 1

As shown in fig. 1 and fig. 2, a photo-thermal electron and photon cooperative emission refrigerating device suitable for cooling an electronic device is characterized by comprising a cathode body 1, an anode body 2, an insulator 3, a voltage source 4 and a light emitting source 5. The cathode body 1 comprises a cathode active layer 11, a cathode conductive layer 12, a cathode isolation layer 13 and a cathode substrate 14. The cathode active layer 11 serves to reduce a barrier for electron emission. The cathode conductive layer 12 is used to absorb photons of the light-emitting source and generate free electrons while making connections to external circuitry. The cathode insulating layer 13 is used to block the connection of the cathode and the cathode substrate. In this embodiment, the cathode body 1 is prepared by sequentially depositing a silicon dioxide insulating layer and a heavily doped highly conductive single crystal silicon layer on a silicon cathode substrate and coating a barium active layer on the surface thereof. The anode body 2 comprises a glass substrate 8, an anode 9 and an anode conducting layer 10. The glass substrate 8 is used for support of the thin film layer anode 9, and the anode conductive layer 10 connects the anode 9 to an external circuit. The anode 9 is a light-transmitting conductive material. In this example, the anode body was formed by sputtering a transparent conductive indium tin oxide layer on a glass substrate and depositing a high conductivity silicon layer on the edges. The insulator 3 is an absolute low-thermal conductivity material and is used for isolating the cathode body 1 and the anode body 2, and simultaneously regulating and controlling the distance between the cathode active layer 11 and the anode 9 and manufacturing a vacuum environment beneficial to electron transportation. In this embodiment, the insulator is formed by growing a silicon dioxide layer on the silicon layer of the anode body 2, and sealing with the cathode layer in the cathode body is realized by adopting an anodic bonding manner, and the thickness of the silicon dioxide layer is adjusted and controlled so that the distance between the cathode and the anode is kept to be 0.1-1 mm. The light emitting source 5 is a red laser diode and is powered by a voltage source to generate photons.

The laser diode emits photons of a specific wavelength under the action of an external voltage source. The photons pass through an indium oxide anode with high transmittance and then are incident on the surface of a silicon cathode of a thermionic device. Because the frequency of the photons emitted by the laser diode is greater than the forbidden bandwidth of the silicon cathode, the valence band electrons are excited to the conduction band by the incident photons. Part of the conduction band electrons can absorb the heat energy of the cathode and jump the surface potential barrier of the cathode to emit into vacuum. When there is a positive electric field between the cathode and the anode, electrons escaping into the vacuum will be accelerated and transported to the anode. And the other part of conduction band electrons jump back to the conduction band through radiative recombination, and photons with equal forbidden band widths are emitted. The photons emitted from the cathode will carry energy to collide with the alkali metal vapor 7 from the cathode body 1 to generate plasma, further lowering the temperature of the cathode. In this embodiment, the cathode of the thermal electron refrigeration device is closely attached to the heating power electronic device, and the temperature of the electronic device can be effectively reduced by a method of the photoluminescence thermal electron and photon cooperative emission refrigeration, so that a high-efficiency refrigeration effect is achieved.

Example 2

Fig. 3 shows a photo-induced thermal electron and photon cooperative emission refrigerating device suitable for refrigerating in a refrigerator, which is characterized by comprising a refrigerator storage chamber 15, a thermal electron refrigerating module 16, a heat exchanger 17, a water pipe 18, a water tank 19, a water pump 20, a voltage source 4 and a light emitting source 5. The hot electron refrigeration module 16 is positioned between the refrigerator storeroom 15 and the refrigerator heat dissipation unit, a plurality of hot electron refrigeration devices are connected with the voltage source 4 in a series-parallel connection mode, and the light-emitting source 5 is used as a light source required by photoinduced hot electron refrigeration. The single-hot-electron refrigeration device is the same as the photo-thermionic and photon co-emission refrigeration device described in example 1, and is not described again. The refrigerator radiating unit takes water as a working medium and comprises a heat exchanger 17, a water pipe 18, a water tank 19 and a water pump 20.

The hot electron refrigeration module absorbs heat in the storage chamber of the refrigerator, and under the action of an external power supply and a light source, cold-end electrons are emitted to the hot end without obstruction. The heat exchanger is tightly attached to the hot end of the hot electron refrigeration module, and the hot end heat of the refrigeration module can be effectively absorbed. The cold water in the water tank 19 is delivered to the heat exchanger through the water pump 20, absorbs the hot end heat of the thermoelectric refrigeration module 16, and then returns to the water tank 19 after flowing through the water pipe.

Example 3

Fig. 4 shows a photo-induced thermoelectron and photon cooperative emission refrigerating device suitable for house refrigeration, which is characterized by comprising a thermoelectron refrigerating module 16, a fan 21, a building house 22 and a voltage source 4.

The photo-induced thermionic cooling process is the same as that described in example 2 and will not be described. This example mainly illustrates the implementation of the hot electron refrigeration module for the cooling of a house. The hot electron refrigeration module is formed by connecting a plurality of hot electron refrigeration devices in a series-parallel mode, under the action of sunlight, the cold end of each hot electron refrigeration device emits electrons, and under the action of a voltage source, the electrons carry energy and are accelerated to the hot end of each hot electron device. Under the action of the fan, the heat at the hot end of the hot electron refrigerating device is dissipated to the air outlet. The temperature of the cold end and the hot end of the hot electron refrigerating device is regulated and controlled by regulating the voltage of the voltage source, so that the house is refrigerated.

Claims

1. A method for refrigeration by photo-induced thermoelectron and photon cooperative emission is characterized in that: after the cathode body (1) absorbs photons of the light-emitting source (5) and heat energy of the heat source, internal valence band bound electrons are transited to a conduction band to become hot electrons; part of the thermal electrons carry energy to be emitted to vacuum and conducted to the anode body (2) under the action of the electric field force provided by the voltage source (4); partial hot electrons generate photons through the recombination action with valence band holes, and the photons carry energy to collide with alkali metal vapor (7) from the cathode body (1) to generate plasma, so that the negative space charge effect is weakened, and the emission of the hot electrons is enhanced; the cathode body absorbs the energy of the heat source to reduce the temperature thereof by the mode of the cooperative emission of the thermal electrons and the photons, so as to realize refrigeration.

2. The photo-induced thermoelectron and photon cooperative emission refrigeration method as claimed in claim 1, wherein the method comprises the following steps: the light emitting source (5) is a laser diode or a light emitting diode, and is powered by the voltage source (4) to generate photons; or a natural light source.

3. The photo-induced thermoelectron and photon cooperative emission refrigeration method as claimed in claim 1, wherein the method comprises the following steps: the cathode body (1) comprises a cathode active layer (11), a cathode conducting layer (12), a cathode isolating layer (13) and a cathode substrate (14); the cathode substrate (14) is provided with a cathode isolation layer (13), the cathode conducting layer (12) is arranged on the cathode isolation layer (13), and the cathode active layer (11) is arranged on the cathode conducting layer (12); the cathode active layer (11) is used for reducing the potential barrier of electron emission; the cathode conducting layer (12) is used for absorbing photons of the luminous source (5) and generating free electrons, and meanwhile, the connection with an external circuit is realized; the cathode isolating layer (13) is used for blocking the connection of the cathode conducting layer (12) and the cathode substrate (14).

4. The photo-induced thermoelectron and photon cooperative emission refrigeration method as claimed in claim 1, wherein the method comprises the following steps: the anode body (2) comprises a glass substrate (8), an anode (9), an anode conducting layer (10) and an insulator (3); the surface of the glass substrate (8) is provided with an anode (9) and an anode conducting layer (10), wherein the anode conducting layer (10) is arranged on two sides of the anode (9), and the insulator (3) is arranged on the anode conducting layer (10); the glass substrate (8) is used for supporting the anode (9) film layer, and the anode conducting layer (10) is connected with the anode (9) and an external circuit; the anode (9) is made of a light-transmitting conductive material.

5. The photo-induced thermoelectron and photon cooperative emission refrigeration method as claimed in claim 4, wherein the method comprises the following steps: the insulator (3) is an absolute low-thermal conductivity material and is used for isolating the cathode body (1) and the anode body (2), regulating and controlling the distance between the cathode and the anode and manufacturing a vacuum environment beneficial to electron transportation.

6. A kind of photoinduced thermoelectron and photon cooperate with the emission refrigerating plant, characterized by that: comprises a cathode body (1), an anode body (2), an insulator (3), a voltage source (4) and a luminous source (5); the cathode body (1) absorbs photons emitted by the light emitting source (5) and heat energy of a heat source to generate thermal electrons, part of electrons are emitted to the anode body (2) under the action of the voltage source (4), part of electrons are emitted to the anode body (2) in a form of energy carried by the photons through a composite effect, and collide with alkali metal vapor (7) to generate plasma and enhance the emission of the thermal electrons, so that refrigeration is realized, and the insulator (3) is arranged between the cathode body (1) and the anode body (2) and used for isolating the cathode body (1) and the anode body (2); the alkali metal vapor (7) is cesium or rubidium metal vapor.

7. The photo-thermionic and photon cooperative emission refrigeration system as claimed in claim 6, wherein: the cathode body (1) is characterized in that a cathode isolation layer (13) is deposited on a cathode substrate, a cathode conducting layer (12) grows on the cathode isolation layer (13), and a cathode active layer (11) is coated on the upper surface of the cathode conducting layer (12); (ii) a The cathode substrate (14) is a silicon cathode substrate, the cathode isolation layer (13) is a silicon dioxide insulating layer, the cathode conducting layer (12) is a heavily doped high-conductivity monocrystalline silicon layer, and the cathode active layer (11) is a barium active layer.

8. The photo-thermionic and photon cooperative emission refrigeration system as claimed in claim 6, wherein: the anode body (2) is formed by sputtering a layer of anode (9) on a glass substrate (8) and depositing a layer of anode conducting layer (10) on the edge; the anode (9) is an indium tin oxide transparent conducting layer, and the anode conducting layer (10) is a high-conductivity silicon layer.

9. A photo-thermionic and photon cooperative emission refrigeration unit as claimed in claim 6, 7 or 8, wherein: the insulator (3) is formed by growing a silicon dioxide layer on the anode conducting layer (10), realizing the sealing with the cathode layer (12) in the cathode body in an anode bonding mode, and regulating the thickness of the silicon dioxide layer to ensure that the distance between the cathode (12) and the anode (9) is kept between 0.1 and 1 mm.

10. The photo-thermionic and photon cooperative emission refrigeration system as claimed in claim 6, wherein: the luminous source (5) is an active luminous device or a passive light source; the heat source generates heat electronic devices, refrigerator storerooms or building houses.