CN107367524A - A kind of near field heat radiation experimental provision - Google Patents

Abstract

The invention discloses a near-field thermal radiation experimental measuring device, which relates to the technical field of radiation heat transfer testing, and solves the technical problem of realizing accurate measurement of near-field thermal radiation heat transfer at the micro-nano scale, and the lateral thermal radiation loss is small during measurement And the mechanical structure is simple, the device includes: the upper displacement loading device (1), the lower displacement loading device (2), the sealing chassis device (3), the vacuum cover (4), and also includes the measuring unit (5), distance measuring optical fiber ( 6), the measuring unit (5) is placed between the upper displacement loading device (1) and the lower displacement loading device (2), and the ranging optical fiber (6) runs through the upper displacement loading device (1) Stopping at the measuring unit (5), the distance between the detection samples can be obtained through spectral analysis. The present invention has small lateral heat radiation loss during measurement, can adopt two methods to adjust the distance between samples, and the space can be adjusted in a large range, and realizes accurate measurement of near-field heat radiation heat exchange at the micro-nano scale.

Description

A near-field thermal radiation experimental measurement device

technical field

The present invention relates to the technical field of radiation heat transfer testing, in particular to a near-field heat radiation experiment measuring device, comprising: an upper displacement loading device, a lower displacement loading device, a sealed chassis device, a vacuum cover, a measuring unit, and a distance-measuring optical fiber.

Background technique

All objects in nature, as long as the temperature is above the absolute temperature of zero, will continuously transmit heat outward in the form of electromagnetic waves and particles. This way of transmitting energy is called radiation. The constant thermal vibration of electrons and particles in matter makes the matter radiate electromagnetic waves continuously. The electromagnetic wave radiation generated by heat is called thermal radiation, and the wavelength range is 0.1μm-100μm. Near-field thermal radiation refers to the phenomenon of enhanced thermal radiation at the micro-nano scale, which cannot be explained by the Stefan-Boltzmann law and deviates from Planck's black body radiation law. The concepts of the far and near fields of radiation are: when the distance between two objects is much greater than the dominant wavelength of radiation, the exchange of radiative energy can be described by the Radiative Transfer Equation (RTE) or Planck’s black body distribution, and the thermal radiation is abstracted as particles and photons; The distance is small enough (micro-nano scale), there are wave properties, which can only be described by Maxwell's equations. A simple condition for judging whether near-field radiation can be generated is: the distance between two objects is smaller than the wavelength λmax corresponding to the maximum blackbody radiation force at the temperature (given by Wien's displacement law). At a normal temperature of 300K, the maximum radiation force of a black body corresponds to a wavelength of the order of 10 μm.

Near-field thermal radiation has considerable potential in thermal management. Many scholars have done a lot of research in this area. The theoretical research uses stochastic Maxwell equations combined with fluctuation and dissipation laws, dyadic Green's function and other methods to explore. The mechanism. However, theoretical calculations can only predict the near-field radiative heat transfer of some simple geometries. The general theoretical radiative heat transfer model structures include simple structures such as parallel plates, spheres and plates, and two concentric cylinders. For near-field thermal radiation with complex geometry, there is no perfect theoretical analysis method yet.

In terms of experimental measurement of near-field thermal radiation, it was limited to the technical level in the early stage and did not receive extensive research. It was not until the 1990s that micro-processing technology was used to produce micro-needle detectors for in-depth experimental research on near-field thermal radiation. Up to now, scanning probes Needle technology is still an important method in micro-nanoscale radiation heat transfer measurement experiments. The experimental measurement of near-field thermal radiation usually needs to be carried out under vacuum conditions. The experimental group needs to have a thermal radiation emitter and receiver at the same time, and in the experiment, the emitter and absorber need to be placed at relative positions with a distance of microns or nanometers. , which is the key and difficult problem in the experimental measurement. There are currently three types of near-field thermal radiation measurement devices:

The first type is to use the modified scanning probe as the emitter to measure the near-field thermal radiation between microspheres and flat plates or between microspheres and microspheres. Radiation has more research value and practicality.

The second type uses traditional mechanical devices combined with micro-electromechanical system devices, such as using stepping motors, differential screws, etc. to adjust the distance between the transmitter and the receiver, and generally studies the near-field heat radiation between the plates, and the distance is generally sub-micron The disadvantage is that when the displacement is controlled by the differential screw, the highest resolution is about 1 micron, which is difficult to reach the nanometer level and the mechanical structure is complicated.

The third category is devices processed by micro-nano electromechanical systems, such as suspended film structures and micro-actuator structures. The micro-actuator structure uses the principle of thermal expansion to control the distance between two micro-planes, so as to study the corresponding near-field thermal radiation phenomenon. Disadvantages The structure and manufacturing process are complicated, and deformation analysis such as mechanics is required in advance.

Contents of the invention

Aiming at the deficiencies of the prior art, the technical problem solved by the present invention is to realize the accurate measurement of near-field thermal radiation heat exchange at the micro-nano scale, with small transverse thermal radiation loss and simple mechanical structure during measurement.

In order to solve the above technical problems, the technical solution provided by the present invention is a near-field thermal radiation experimental measurement device, a near-field thermal radiation experimental measurement device, comprising: an upper displacement loading device, a lower displacement loading device, a sealed chassis device, a vacuum cover, measuring unit and distance measuring optical fiber, the sliding screw connects the upper displacement loading device, the lower displacement loading device, and the sealing chassis device from top to bottom in turn, and the ball sleeve is set on the sliding screw to control the lower displacement loading device. Relative movement is limited, the vacuum cover covers the upper displacement loading device and the lower displacement loading device and is placed on the sealed chassis, and the measuring unit is placed between the upper displacement loading device and the lower displacement loading device , the ranging optical fiber passes through the upper displacement loading device and ends on the measuring unit;

The upper displacement loading device includes an upper bracket, an upper loading plate, a compression spring, a T-shaped table and a screw rod, and the screw rod is located in the center of the upper bracket and threaded through the upper bracket from top to bottom to withstand the upper loading plate And can move up and down through the thread, the upper loading plate, the compression spring, and the T-shaped table are successively connected, and the sliding screw passes through the ball sleeve 17 to limit the relative position of the T-shaped table and fix it under the upper bracket;

The lower displacement loading device includes a piezoelectric driver, an angle regulator, a substrate, an directional steel ball pressure sensor, and a lower bracket, and the piezoelectric driver, angle regulator, substrate, directional steel ball pressure sensor, and lower bracket are connected in sequence, and the The sliding screw passes through the ball sleeve to relatively limit the base plate and passes through the base plate and the lower bracket and is fixed on the chassis panel;

The sealed chassis device 3 includes a chassis panel, a level adjusting rod, a chassis bottom plate, a hydraulic cylinder, a pressure power source, a sealer, a wire connector, and a vacuum exhaust pipe, and the chassis panel, the level adjusting rod, and the chassis bottom plate are connected in sequence, The pressure power source is placed on the bottom plate of the chassis, on which it bears against the hydraulic cylinder, the hydraulic cylinder passes through the chassis panel and connects with the bottom surface of the lower bracket, and the sealer is connected to the wire connector and The vacuum extraction air pipes all pass through the chassis panel.

The measuring unit includes a heater and a copper thermal expansion board, a heat conduction pad, a heat conduction pad, an upper sample holder, a lower sample holder, a heat flow meter and a thermoelectric device, a temperature sensor and a copper raised platform, and the heater and a copper The thermal expansion board, the heat conduction pad, and the upper sample holder are attached to each other in sequence, and the lower sample holder, heat conduction pad, heat flow meter, thermoelectric device, and the copper heightening platform are attached to each other in sequence, and the temperature sensor is arranged on the The two sides of the copper raised platform are symmetrical.

Further, the surface of the heater, the copper thermal expansion board and the copper raised platform is gold-plated or aluminum-plated.

Further, there are temperature measuring holes on the side of the heater and the copper thermal expansion board, and the thermocouple should be embedded in the deepest part of the temperature measuring hole.

Further, the upper sample holder and the lower sample holder can be replaced by high-precision optical plates according to experimental needs.

In this embodiment, the flat sample is clamped by the upper sample holder and the lower sample holder, and the size of the sample should be cut according to the size of the upper sample holder and the lower sample holder. Surface treatment is required to achieve suitable roughness and flatness;

The upper sample holder and the lower sample holder can also be replaced by a high-precision optical flat plate. Preferably, the surface curvature of the high-precision optical flat plate is less than 50nm, and then sprayed on the high-precision optical flat plate Or etch the material to be tested.

The distance-measuring fiber is used to measure the distance between the measured parallel samples. The measurement principle is optical interferometry, and the distance of the gap can be obtained through the analysis of the spectrum. current method, etc.

Adopting the technical scheme of the present invention can obtain the following beneficial effects:

1. Through the gold-plated or aluminum-plated surface treatment on the relevant parts of the measurement unit, the surface radiation absorption rate is reduced, the influence of the environment during the experimental measurement is reduced, and the lateral heat radiation loss is small during the measurement, thus tending to one-dimensional heat dissipation. transfer.

2. Through the design of the displacement-loading system, the distance between the two samples can be adjusted in two ways, so that the adjustable range is greatly increased.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a schematic diagram of the structure of the measuring unit.

detailed description

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited.

Fig. 1, Fig. 2 have shown the structure of the present invention, a kind of near-field thermal radiation experiment measuring device, comprises upper displacement loading device 1, lower displacement loading device 2, sealed chassis device 3, vacuum cover 4, measuring unit 5 and measuring device From the optical fiber 6, the sliding screw 7 is sequentially connected to the upper displacement loading device 1, the lower displacement loading device 2, and the sealing chassis device 3 from top to bottom, and the ball sleeve 8 is set on the sliding screw 7 to load the lower displacement. The relative movement of the device 2 is limited, the vacuum cover 4 covers the upper displacement loading device 1 and the lower displacement loading device 2 and is placed on the sealed chassis 3, and the measuring unit 5 is placed on the upper displacement loading device 1. Between the lower displacement loading devices 2, the ranging optical fiber 6 runs through the upper displacement loading device 1 and ends on the measuring unit 5;

The upper displacement loading device 1 includes an upper bracket 11, an upper loading plate 12, a compression spring 13, a T-shaped table 14 and a screw rod 15, and the screw rod 15 is located at the center of the upper bracket 11 and threaded through the upper bracket 11 from top to bottom. The bracket 11 bears against the upper loading plate 12 and can move up and down through threads, the upper loading plate 12, the compression spring 13, and the T-shaped table 14 are connected in sequence, and the sliding screw 16 passes through the ball sleeve 17 to the T-shaped table. The platform 14 is relatively limited and fixed under the upper bracket 11;

The lower displacement loading device 2 includes a piezoelectric driver 21, an angle regulator 22, a substrate 23, an orientation steel ball pressure sensor 24 and a lower bracket 25, and the piezoelectric driver 21, an angle regulator 22, a substrate 23, an orientation steel ball The pressure sensor 24 and the lower bracket 25 are connected in sequence, and the sliding screw 7 passes through the ball sleeve 8 to limit the relative position of the base plate 23 and passes through the base plate 23 and the lower bracket 25 and is fixed on the chassis panel 31;

The sealed chassis device 3 includes a chassis panel 31, a level adjustment rod 32, a chassis bottom plate 33, a hydraulic cylinder 34, a pressure power source 35, a sealer and a wire connector 36, and a vacuum exhaust pipe 37. The chassis panel 31, the level The adjusting rod 32 and the chassis bottom plate 33 are connected in sequence, and the pressure power source 35 is placed on the chassis bottom plate 33, which bears on the hydraulic cylinder 34, and the hydraulic cylinder 34 passes through the chassis panel 31 and the The bottom surface of the lower bracket 25 is connected, and the sealer, the wire connector 36 and the vacuum exhaust air pipe 37 all pass through the chassis panel 31 .

As shown in Figure 2, the measurement unit 5 includes a heater and a copper thermal expansion board 51, a thermal pad 52, a thermal pad 53, an upper sample holder 54, a lower sample holder 55, a heat flow meter and a thermoelectric device 56, Temperature sensor 57 and copper heightening platform 58, described heater and copper thermal expansion plate 51, thermal conduction pad 52, upper sample holder 54 stick together successively, described lower sample holder 55, thermal conduction pad 53, heat flow meter and The thermoelectric device 56 and the copper raised platform 58 are attached to each other in sequence, and the temperature sensor 57 is arranged on both sides of the copper raised platform 58 and is left-right symmetrical.

Further, the surface of the heater, the copper thermal expansion board 51 and the copper raised platform 58 is gold-plated or aluminum-plated.

Further, there are temperature measuring holes on the side of the heater and the copper thermal expansion plate 51, and the thermocouple should be embedded in the deepest part of the temperature measuring hole.

Further, the upper sample holder 54 and the lower sample holder 55 can be replaced by optical flat plates according to experimental needs.

In this embodiment, the flat sample is clamped by the upper sample holder 54 and the lower sample holder 55, and the size of the sample should be determined according to the size of the upper sample holder 54 and the lower sample holder 55. Cutting, surface treatment is required before sample measurement to achieve proper roughness and flatness;

The upper sample holder 54 and the lower sample holder 55 can also be replaced by a high-precision optical flat plate. Preferably, the surface curvature of the high-precision optical flat plate is less than 50nm, and then the high-precision optical flat plate Spray or etch the material to be tested.

The distance measuring fiber 6 is used to measure the distance between the measured parallel samples. The measurement principle is optical interferometry, and the distance of the gap can be obtained through the analysis of the spectrum. Or tunnel current method, etc.

In this embodiment, there are two ways to adjust the distance between two parallel plate samples through this device:

In this embodiment, there are two ways to adjust the distance between the two parallel plate samples:

The first is to first adjust the position of the upper displacement loading device 1 and fix it, and then perform a rough displacement through the lower displacement loading device 2. After reaching a suitable height, the angle adjuster 22 is adjusted to make the two samples parallel, Then adjust the piezoelectric driver 21 to perform fine displacement. This method adopts the method of "fitting below" and can be used to measure the near-field to far-field thermal radiation heat transfer with submicron to millimeter spacing;

The second way is to use specially processed adiabatic and equidistant micro-nano particles as spacers to regulate the distance between the two samples. The micro-nano particles are evenly distributed between the two samples, and then the sample is loaded by controlling the upper displacement loading device 1, wherein The load is mainly applied by the compression spring 13 , and the applied pressure can be monitored by the directional steel ball pressure sensor 24 , which can be used to measure the near-field heat radiation heat transfer with a spacing of 100 nanometers to microns.

In this embodiment, the temperature sensor 57, the heat flow meter and the thermoelectric device 56 must be calibrated in advance, and the temperature of the heater and the copper thermal expansion plate 51 is monitored by a platinum resistance temperature sensor, which feeds back a signal to a Temperature controller, through feedback control, the temperature change of the heat conduction pad 52 can be controlled within 1°C, and the heat flow from the heater and the copper thermal expansion board 51 to the heat flow meter and the thermoelectric device 56 can be controlled by a thermoelectric The heat flow meter on the device is obtained from the thermoelectric device 56, and its output voltage is in a linear relationship with the temperature difference between the upper and lower surfaces of the heat flow sensor sensing plate. To obtain a suitable heat transfer calculation, the sensitivity of the heat flow sensor needs to be determined in advance Regional calibration; after the sample spacing is adjusted, connect the data wiring and cover the vacuum cover 4, and vacuum the closed space inside the vacuum cover 4 through the vacuum exhaust pipe 37, and wait for the inside of the vacuum cover 4 to vacuumize. When the vacuum degree reaches below 10-3Pa, select the heater and the copper thermal expansion plate 51 arranged up and down and the heat flow meter and the thermoelectric device 56 to adjust the temperature difference according to the needs; after reaching a suitable vacuum degree and stable state, according to the The heat flow data q in the heat flow meter arranged in the measurement unit 5 and the thermoelectric device 56 and the temperature T1 of the thermocouple embedded in the upper side of the copper thermal expansion board 51, the temperature T2 measured by the temperature sensor 57 combined with the used Knowing the physical properties of materials such as the thermal conductivity and thickness of the copper thermal expansion plate 51 and the upper sample holder 54 and the lower sample holder 55 holders, the temperature Th, Tc and the upper and lower surfaces of the sample can be calculated The heat transfer coefficient h=q/(Th-Tc) of near-field thermal radiation.

The technical solution of the present invention can adjust the distance between samples in two ways, and the distance can be adjusted in a large range, realizing the accurate measurement of near-field thermal radiation heat transfer at the micro-nano scale.

The technical solutions of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, replacements and modifications to these embodiments still fall within the protection scope of the present invention.

Claims (10)

1. A near-field thermal radiation experiment measurement device, including: an upper displacement loading device (1), a lower displacement loading device (2), a sealed chassis device (3) and a vacuum cover (4), and the sliding screw (7) sequentially from The upper displacement loading device (1), the lower displacement loading device (2), and the sealing chassis device (3) are connected from top to bottom, and the ball sleeve (8) is set on the sliding screw (7) to control the lower displacement. The relative movement of the loading device (2) is limited, and the vacuum cover (4) covers the upper displacement loading device (1) and the lower displacement loading device (2) and is placed on the sealed chassis (3). In that: it also includes a measuring unit (5) and a distance measuring optical fiber (6), the measuring unit (5) is placed between the upper displacement loading device (1) and the lower displacement loading device (2), the distance measuring The optical fiber (6) runs through the upper displacement loading device (1) and terminates on the measurement unit (5), and the distance between the detected sample gaps can be obtained through spectral analysis. 2. The near-field thermal radiation experimental measurement device according to claim 1, characterized in that: the upper displacement loading device (1) includes an upper bracket (11), an upper loading plate (12), a compression spring (13), T-shaped table (14) and screw rod (15), the screw rod (15) is located in the center of the upper bracket (11) and threaded from top to bottom through the upper bracket (11) to withstand the upper loading plate (12 ) and can move up and down through the thread, the upper loading plate (12), compression spring (13), and T-shaped table (14) are connected in sequence, and the sliding screw (16) passes through the ball sleeve (17) to the T The type table (14) is relatively limited and fixed under the upper bracket (11). 3. The near-field thermal radiation experimental measurement device according to claim 1, characterized in that: the lower displacement loading device (2) includes a piezoelectric driver (21), an angle adjuster (22), a substrate (23), The directional steel ball pressure sensor (24) and the lower bracket (25), the piezoelectric driver (21), the angle adjuster (22), the base plate (23), the directional steel ball pressure sensor (24), the lower bracket (25) connected in sequence, the sliding screw (7) passes through the ball sleeve (8) to limit the relative position of the base plate (23), passes through the base plate (23), the lower bracket (25) and is fixed on the chassis panel (31). 4. The near-field thermal radiation experiment measurement device according to claim 1, characterized in that: the sealed chassis device (3) includes a chassis panel (31), a level adjustment rod (32), a chassis bottom plate (33), a hydraulic Cylinder (34), pressure power source (35), sealer and wire connector (36) and vacuum exhaust air pipe (37), the chassis panel (31), spirit level adjustment rod (32), chassis bottom plate (33) connected in sequence, the pressure power source (35) is placed on the chassis bottom plate (33), on which it bears the hydraulic cylinder (34), and the hydraulic cylinder (34) passes through the chassis panel (31) Connecting with the bottom surface of the lower bracket (25), the sealer and wire connector (36) and the vacuum exhaust air pipe (37) all pass through the chassis panel (31). 5. The near-field thermal radiation experiment measurement device according to claim 1, characterized in that: the measurement unit (5) includes a heater and a copper thermal expansion board (51), a heat conduction pad (52), a heat conduction pad (53 ), the upper sample holder (54), the lower sample holder (55), the heat flow meter and the thermoelectric device (56), the temperature sensor (57) and the copper elevated platform (58), the heater and the copper thermal expansion The plate (51), the thermal pad (52), and the upper sample holder (54) are attached in sequence, and the lower sample holder (55), the thermal pad (53), the heat flow meter and the thermoelectric device (56), and the The copper raised platforms (58) are attached to each other in sequence, and the temperature sensor (57) is arranged on both sides of the copper raised platform (58) and is left-right symmetrical. 6 . The near-field thermal radiation experiment measuring device according to claim 5 , characterized in that: the surfaces of the heater, the copper thermal expansion board ( 51 ) and the copper heightening platform ( 58 ) are gold-plated or aluminum-plated. 7. The near-field thermal radiation experiment measuring device according to claim 6, characterized in that: the side of the heater and the copper thermal expansion plate (51) are punched with temperature measuring holes. 8. The near-field thermal radiation experimental measurement device according to any one of claims 5 to 7, characterized in that: the upper sample holder (54) and the lower sample holder (55) can be used with high precision Optical flat replacement. 9. The near-field thermal radiation experimental measurement device according to claim 8, characterized in that: the unevenness of the surface of the high-precision optical flat plate is less than 50nm. 10. The near-field thermal radiation experimental measuring device according to claim 9, characterized in that: the material to be tested is sprayed or etched on the high-precision optical plate.