A nanofluid circulation system for enhancing heat transfer in microchannels

Abstract

The present invention provides a nanofluid circulation system for enhancing heat transfer in a microchannel, comprising a liquid storage tank, a gas fuel tank, nanoparticles, a premixing chamber, a mixed gas ejector, a micro-combustion chamber, an arc filter and a nanoparticle dispersion tank; the liquid storage tank is provided with nanoparticles, the gas fuel tank and the liquid storage tank are respectively connected to the premixing chamber, and are used to input gas combustion and nanoparticles into the premixing chamber for mixing; the mixed premixed gas is ejected into the micro-combustion chamber through the mixed gas ejector, the micro-combustion chamber is provided with an arc filter at the end, and the outlet of the arc filter is connected to the nanoparticle dispersion tank for collecting nanoparticles. The present invention makes the temperature distribution in the combustion chamber more uniform and enhances the heat transfer efficiency in the microchannel.

Description

Technical Field

[0001] The invention relates to the technical field of microscale heat transfer, and in particular to a nanofluid circulation system for enhancing heat transfer in a microchannel. Background Art

[0002] The micro-thermal photoelectric system converts the chemical energy of hydrogen or hydrocarbon fuels into thermal energy directly through combustion in the microsystem, and then generates electricity by absorbing wall radiation through photosensitive materials. The micro-burner is the core component of the micro-thermal photoelectric system, and has high requirements for its stability, its ability to provide a continuous and stable high-temperature heat source, high energy density, good safety performance, and tail gas emissions. The micro-thermal photoelectric system has a good application prospect, but it is very difficult to achieve stable combustion of fuel in a micro-scale burner. The combustion chamber is small in size and has a high heat dissipation rate, which makes the conventional flame unstable and prone to wall flameout. The maximum temperature difference on the wall often reaches more than 200K, the temperature distribution is uneven, and the thermal efficiency is reduced.

[0003] Nanoparticles, also known as nanodust, refer to microscopic particles of nanometer scale. It is defined as particles smaller than 100 nanometers in at least one dimension. It is a new type of heat transfer medium with uniformity, stability and high thermal conductivity. This is an innovative study on the application of nanotechnology in the traditional field of thermal energy engineering. Nanoparticles have great potential application prospects in the fields of energy, chemical industry, automobile, construction, microelectronics, information, etc., thus becoming a research hotspot in many fields such as materials, physics, chemistry, and heat transfer. Experimental studies have shown that the use of appropriate nanoparticles can achieve the purpose of enhancing heat transfer and enhancing the critical heat flow of the heat transfer surface. At present, nanoparticles have been widely used in the fields of materials, chemistry, physics, heat transfer, and medicine.

[0004] Catalytic combustion occurs on the surface of the catalyst and has a good prospect in the field of micro-combustion. Compared with gas phase combustion, catalytic combustion can reduce the activation energy of the reaction, has good thermal conductivity, and has a positive effect on gas preheating and stable combustion. The common catalytic combustion method usually covers the catalyst on the inner wall of the microchannel, which has a good catalytic effect near the wall and a more uniform temperature distribution, but the effect is not as good as near the wall for those far away from the wall. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a nanofluid circulation system for enhancing heat transfer in a microchannel. Although nanoparticles may agglomerate during the flow process due to their extremely small size, the particle size is still at the nanometer level even after agglomeration. After being blown into a micro-combustion chamber, no deposition will occur in the combustion chamber, and they will be blown out of the combustion chamber along with the exhaust gas. Moreover, this agglomeration can also facilitate the capture of particles by the filter. Therefore, nano-scale catalysts are used. On the basis of nanoparticles being able to enhance heat transfer, the catalytic effect of the catalyst is utilized to play a very effective catalytic role in the micro-combustion chamber. A nanofluid circulation system for catalysis and enhanced heat transfer in a microchannel is provided for a micro-thermal photoelectric system, which makes the temperature distribution in the combustion chamber more uniform and enhances heat transfer in the microchannel.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A nanofluid circulation system for enhancing heat transfer in a microchannel, comprising a liquid storage tank, a gas fuel tank, nanoparticles, a premixing chamber, a mixed gas ejector, a micro combustion chamber, an arc filter and a nanoparticle dispersion tank;

[0008] Nanoparticles are arranged in the liquid storage tank, and the gas fuel tank and the liquid storage tank are respectively connected to the premixing chamber, for mixing gas combustion and nanoparticles input into the premixing chamber; the mixed premixed gas is ejected into the micro combustion chamber through the mixed gas ejector, and an arc filter is arranged at the end of the micro combustion chamber, and the outlet of the arc filter is connected to the nanoparticle dispersion tank for collecting nanoparticles. After ignition, the premixed gas is fully catalytically burned. Since the nanoparticles are fine powders, they have a certain flow rate when entering the micro combustion chamber, so the particles will not be deposited in the micro combustion chamber, but will be blown out of the micro combustion chamber directly with the exhaust gas. The outlet of the micro combustion chamber is connected to the arc filter. After the nanoparticles are discharged from the micro combustion chamber, the arc filter separates the nanoparticles from the exhaust gas at the outlet, and then sends the nanoparticles into the nanoparticle dispersion tank.

[0009] Furthermore, the nanoparticles are catalysts with a particle size of less than 20 nm, and the catalyst material is any one of Pd, Pt, Rh, and Au.

[0010] Furthermore, a first flow setter is provided between the gas fuel tank and the premixing chamber, a second flow setter is provided between the liquid storage tank and the premixing chamber, and a nanofluid particle size detector is installed in the premixing chamber to detect the concentration of nanoparticles and gas fuel in the premixing chamber.

[0011] Furthermore, the invention also includes a controller, wherein the controller controls the openings of the first flow setter and the second flow setter respectively according to the concentration of the nanoparticles and the concentration of the gas fuel.

[0012] Furthermore, a stirrer is placed on the top of the nanoparticle dispersion tank, and a high-frequency ultrasonic disperser is placed on the bottom of the nanoparticle dispersion tank.

[0013] Furthermore, the nanoparticle dispersion tank outlet transports the nanoparticles to the liquid storage tank through a loop pipeline device.

[0014] Furthermore, a filter screen is provided at the outlet of the nanoparticle dispersion tank, and the filter screen is used to filter nanoparticles with a particle size greater than 20 nm.

[0015] Furthermore, the loop pipeline equipment includes a pump and a pressure stabilizer, and the outlet of the nanoparticle dispersion tank is connected to the liquid storage tank through the pump and the pressure stabilizer in sequence.

[0016] The beneficial effects of the present invention are:

[0017] 1. The nanofluid circulation system for enhancing heat transfer in microchannels described in the present invention, nanoparticles are a new type of heat exchange medium that is uniform, stable, and highly thermally conductive. The use of nanoparticles can enhance heat transfer in micro-combustion chambers.

[0018] 2. The nanofluid circulation system for enhancing heat transfer in microchannels described in the present invention uses nanoparticles with a particle size of less than 20 nm. The particle size is extremely small and can be blown out of the micro-combustion chamber along with the exhaust gas without being deposited in the micro-combustion chamber, thereby reducing subsequent processing steps.

[0019] 3. In the nanofluid circulation system for enhancing heat transfer in microchannels of the present invention, the material of the nanoparticles is a catalyst, which has a good catalytic effect on the micro-combustion chamber. The catalyst is prepared into nanoparticles and sprayed into the micro-combustion chamber, which can strengthen the contact with the gas fuel and strengthen the catalytic effect on the gas fuel. The nanoparticles agglomerate in the micro-combustion chamber, and the agglomeration between the particles is conducive to the capture of the particles.

[0020] 4. In the nanofluid circulation system for enhanced heat transfer in microchannels described in the present invention, the flow setter controls the flow of nanoparticles and gas fuel by receiving the concentration detection signal of the nanofluid particle size detector, thereby realizing an intelligent controllable design.

[0021] 5. In the nanofluid circulation system for enhancing heat transfer in microchannels described in the present invention, the arc filter can collect the tail gas and nanoparticles well, and then send the nanoparticles into the nanofluid dispersion tank to reduce the waste of nanoparticles.

[0022] 6. The nanofluid circulation system for enhancing heat transfer in microchannels of the present invention can disperse the nanoparticles agglomerated at the outlet of the microcombustion chamber by using the agitator and high-frequency ultrasonic disperser inside the nanofluid dispersion tank, thereby preventing the agglomeration of nanoparticles from affecting the combustion performance of the microcombustion chamber. The filter screen provided at the outlet of the nanofluid can achieve secondary filtration of nanoparticles, and return particles less than 20nm that meet the experimental requirements to the liquid storage tank.

[0023] 7. The nanofluid circulation system for enhancing heat transfer in microchannels described in the present invention has a pump and a voltage stabilizer arranged in the loop pipeline, which transports the nanoparticles to the liquid storage tank to prevent the nanoparticles from clogging the loop, thereby maintaining the normal operation of the loop system, realizing the recycling of nanoparticles, and reducing waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the nanofluid circulation system for enhancing heat transfer in microchannels according to the present invention.

[0026] Figure 2 This is a schematic structural diagram of the nanofluid dispersion tank described in the present invention.

[0027] In the figure:

[0028] 1-liquid storage tank; 2-gas fuel tank; 3-first flow setter; 4-second flow setter; 5-premixing chamber; 6-mixed gas ejector; 7-micro combustion chamber; 8-nanofluid particle size detector; 9-arc filter; 10-nanoparticle dispersion tank; 11-pump; 12-stabilizer; 13-high-frequency ultrasonic disperser; 14-filter; 15-agitator. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0032] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] like Figure 1 As shown, the nanofluid circulation system for enhancing heat transfer in a microchannel of the present invention comprises a liquid storage tank 1, a gas fuel tank 2, nanoparticles, a premixing chamber 5, a mixed gas ejector 6, a micro combustion chamber 7, an arc filter 9, a nanoparticle dispersion tank 10 and a controller;

[0034] Nanoparticles are arranged in the liquid storage tank 1. The nanoparticles are catalysts with a particle size less than 20 nm. The catalyst material is any one of Pd, Pt, Rh, and Au.

[0035] The gas fuel tank 2 and the liquid storage tank 1 are respectively connected to the premixing chamber 5, and are used to input the gas combustion and the nanoparticles into the premixing chamber 5 for mixing; the mixed premixed gas is injected into the micro combustion chamber 7 through the mixed gas ejector 6, and an arc filter 9 is provided at the end of the micro combustion chamber 7. The outlet of the arc filter 9 is connected to the nanoparticle dispersion tank 10 for collecting nanoparticles.

[0036] A first flow rate setter 3 is provided between the gas fuel tank 2 and the premixing chamber 5, a second flow rate setter 4 is provided between the liquid storage tank 1 and the premixing chamber 5, and a nanofluid particle size detector 8 is installed in the premixing chamber 5 to detect the concentrations of nanoparticles and gas fuel in the premixing chamber 5. The controller controls the openings of the first flow rate setter 3 and the second flow rate setter 4 respectively according to the concentrations of the nanoparticles and the gas fuel.

[0037] like Figure 2 As shown, a stirrer 15 is placed on the top of the nanoparticle dispersion tank 10, and a high-frequency ultrasonic disperser is placed at the bottom of the nanoparticle dispersion tank 10. The outlet of the nanoparticle dispersion tank 10 transports the nanoparticles to the liquid storage tank 1 through a loop pipeline device. A filter screen 14 is provided at the outlet of the nanoparticle dispersion tank 10, and the filter screen 14 is used to filter nanoparticles with a particle size greater than 20nm. The loop pipeline device includes a pump 11 and a regulator 12, and the outlet of the nanoparticle dispersion tank 10 is connected to the liquid storage tank 1 through the pump 11 and the regulator 12 in turn.

[0038] Working principle of the present invention:

[0039] When the gas combustion and the nanoparticles enter the premixing chamber 5 respectively, the disturbance in the premixing chamber is also enhanced, so that the premixed gas is mixed more evenly. The nanofluid particle size detector 8 can detect the concentration of nanoparticles and the gas fuel concentration in the premixing chamber. The controller controls the opening of the first flow setter 3 and the second flow setter 4 according to the concentration of nanoparticles and the concentration of gas fuel. The premixed gas after being mixed evenly is injected into the micro combustion chamber 7 through the mixed gas ejector 6. After ignition, catalytic combustion is fully carried out. Since the nanoparticle powder is small, it has a certain flow rate when entering the micro-combustion chamber, so the particles will not be deposited in the micro-combustion chamber, and will be blown out of the micro-combustion chamber directly with the tail gas. The outlet of the micro-combustion chamber is connected to the arc filter 9. After the nanoparticles are discharged from the micro-combustion chamber, the arc filter 9 separates the nanoparticles from the tail gas at the outlet, and then sends the nanoparticles into the nanoparticle dispersion tank 10. The nanoparticle dispersion tank 10 is provided with an agitator 15 and a high-frequency ultrasonic disperser 13, which can disperse the nanoparticles agglomerated at the outlet of the micro-combustion chamber to prevent the agglomeration of nanoparticles from affecting the combustion performance of the micro-combustion chamber. The filter 14 set at the outlet of the nanofluid can realize secondary filtration of nanoparticles, and the particles less than 20nm that meet the experimental requirements are sent back to the liquid storage tank through the loop pipeline equipment. The loop pipeline equipment is provided with a pump 11 and a voltage stabilizer 12 to provide power and stable transportation for sending the nanoparticles back to the liquid storage bottle, so as to realize the repeated recycling of nanoparticles, avoid waste, and save resources.

[0040] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0041] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nanofluid circulation system for enhancing heat transfer in a microchannel, characterized in that: It comprises a liquid storage tank (1), a gas fuel tank (2), nanoparticles, a premixing chamber (5), a mixed gas ejector (6), a micro combustion chamber (7), an arc filter (9) and a nanoparticle dispersion tank (10); Nanoparticles are arranged in the liquid storage tank (1); the gas fuel tank (2) and the liquid storage tank (1) are respectively connected to the premixing chamber (5) for inputting the gas fuel and the nanoparticles into the premixing chamber (5) for mixing; the mixed premixed gas is injected into the micro combustion chamber (7) through the mixed gas ejector (6); an arc filter (9) is arranged at the end of the micro combustion chamber (7); the outlet of the arc filter (9) is connected to a nanoparticle dispersion tank (10) for collecting the nanoparticles.

2. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 1, characterized in that: The nanoparticles are catalysts with a particle size less than 20 nm, and the catalyst material is any one of Pd, Pt, Rh, and Au.

3. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 1, characterized in that: A first flow rate setter (3) is provided between the gas fuel tank (2) and the premixing chamber (5), a second flow rate setter (4) is provided between the liquid storage tank (1) and the premixing chamber (5), and a nanofluid particle size detector (8) is installed in the premixing chamber (5) for detecting the concentration of nanoparticles and gas fuel in the premixing chamber (5).

4. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 3, characterized in that: It also includes a controller, which controls the openings of the first flow setter (3) and the second flow setter (4) respectively according to the concentration of the nanoparticles and the concentration of the gas fuel.

5. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 1, characterized in that: A stirrer (15) is placed on the top of the nanoparticle dispersion tank (10), and a high-frequency ultrasonic disperser is placed on the bottom of the nanoparticle dispersion tank (10).

6. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 1, characterized in that: The nanoparticle dispersion tank (10) outlet transports the nanoparticles to the liquid storage tank (1) through a loop pipeline device.

7. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 6, characterized in that: The outlet of the nanoparticle dispersion tank (10) is provided with a filter screen (14), and the filter screen (14) is used to filter nanoparticles with a particle size greater than 20 nm.

8. The nanofluid circulation system for enhancing heat transfer in microchannels according to claim 6, characterized in that: The loop pipeline equipment comprises a pump (11) and a pressure stabilizer (12), and the outlet of the nanoparticle dispersion tank (10) is connected to the liquid storage tank (1) via the pump (11) and the pressure stabilizer (12) in sequence.

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