A granular packed bed test rig and a test method thereof

Abstract

This invention provides a particle stacking bed test bench and its testing method, including a support frame, an airflow generating device, a heating device, a temperature measuring device, a wind pressure measuring device, a wind speed measuring device, and a particle stacking device having a stacking cavity for particle stacking. The airflow generating device, the heating device, and the particle stacking device are mounted on the support bed. A first end face of the particle stacking device connected to the output end of the airflow generating device and a second end face opposite to the first end face are hollowed out. The first and second end faces are respectively connected to the stacking cavity. A heating window is provided at the bottom of the particle stacking device, and the heating device is embedded in the heating window. The collecting end of the temperature measuring device is inserted into the stacking cavity. The wind pressure measuring device collects the wind pressure near the first and second end faces of the stacking cavity, and the wind speed measuring device collects the wind speed near the first end face of the stacking cavity. This invention facilitates the acquisition of heat conduction and heat transfer patterns between particles.

Description

Technical Field

[0001] This invention relates to the field of particle packed bed heat exchange and heat conduction technology, and in particular to a particle packed bed test bench and its test method. Background Technology

[0002] Currently, during the loading, unloading, and transportation of bulk cargo at ports, the high-speed flow of bulk cargo particles and the impact and friction between them and the bulk cargo equipment can lead to the accumulation of a large amount of heat at the contact surface, forming localized high temperatures. This high-speed contact and relative motion between the bulk cargo and the equipment generates heat and high temperatures, which is the fundamental reason for the reduced service life of the equipment. This not only increases the downtime and maintenance costs of port bulk cargo conveying equipment but also severely restricts the efficiency of port bulk cargo conveying equipment and increases transportation costs. Because bulk cargo consists of discrete particles, heat transfer involves both contact heat conduction between particles and convective heat transfer between particles and the air in the gaps, making it difficult to calculate the temperature at the contact surface between the bulk cargo and the equipment. Furthermore, the irregular geometry of the bulk cargo particles, their variable motion behavior, and their random distribution during flow, along with the complex operating conditions of the bulk cargo equipment, further pose significant challenges to the accurate calculation of the temperature of the bulk cargo equipment.

[0003] Therefore, it is necessary to develop a particle-stacking bed test bench and its test method to obtain the heat conduction and heat transfer laws between particles, thereby improving the accuracy of temperature calculation for bulk cargo equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a particle bed test bench and its test method to solve the problem of low accuracy in temperature calculation of existing bulk cargo equipment.

[0005] To solve the above-mentioned technical problems, the present invention provides a particle stacking bed test bench, including a support frame, an airflow generating device, a heating device, a temperature measuring device, a wind pressure measuring device, a wind speed measuring device, and a particle stacking device having a stacking cavity for particle stacking. The airflow generating device, the heating device, and the particle stacking device are disposed on the support bed. The first end face of the particle stacking device connected to the output end of the airflow generating device and the second end face opposite to the first end face are hollowed out. The first end face and the second end face are respectively connected to the stacking cavity. A heating window is provided at the bottom of the particle stacking device, and the heating device is embedded in the heating window. The collecting end of the temperature measuring device is inserted into the stacking cavity. The wind pressure measuring device collects the wind pressure near the first end face and the second end face of the stacking cavity. The wind speed measuring device collects the wind speed near the first end face of the stacking cavity.

[0006] Optionally, the airflow generating device includes a centrifugal fan and a ventilation duct, wherein the output end of the centrifugal fan is connected to the input end of the ventilation duct, and the output end of the ventilation duct is connected to the first end face of the particle accumulation device.

[0007] Optionally, the airflow generating device further includes a rectifier for converting irregularly flowing high-pressure airflow into regularly flowing high-pressure airflow, wherein the input end of the rectifier is connected to the output end of the ventilation pipe, and the output end of the rectifier is connected to the first end face of the particle accumulation device.

[0008] Optionally, the particle stacking device includes a base plate, a cover plate, two side plates, and two grid plates. The two side plates are respectively disposed opposite to each other on the base plate, and the two grid plates are respectively disposed opposite to each other on the base plate. The side plates are perpendicular to the grid plates. The cover plate covers the two side plates and the two grid plates. The base plate, the cover plate, the two side plates, and the two grid plates form the stacking cavity. One grid plate has a first end face, and the other grid plate has a second end face. A heating window is provided on the base plate.

[0009] Optionally, the base plate, the cover plate, and the two side plates are all mica plates.

[0010] Optionally, the temperature measuring device includes multiple thermocouples, each thermocouple including a thermocouple probe and a temperature display for displaying the temperature information collected by the thermocouple probe. The particle stacking device has multiple mounting holes, and the thermocouple probe is installed in the mounting holes.

[0011] Optionally, the wind speed measuring device includes a first anemometer, which is installed on the side of the particle accumulation device near the airflow generating device and is partially located within the accumulation cavity; the wind speed measuring device also includes a second anemometer, which is installed on the side of the particle accumulation device away from the airflow generating device and is partially located within the accumulation cavity.

[0012] Optionally, the wind pressure measuring device includes a first pitot tube, a second pitot tube, a first clamping member, a second clamping member, a first wind pressure gauge, and a second wind pressure gauge. The first clamping member is installed on the particulate matter accumulation bed. The first pitot tube is installed on the first clamping member and extends into the accumulation cavity on the side near the airflow generating device. The first wind pressure gauge is installed inside the first pitot tube to measure the total pressure of the airflow. The second clamping member is installed on the particulate matter accumulation bed. The second pitot tube is installed on the second clamping member and extends into the accumulation cavity on the side away from the airflow generating device. The second wind pressure gauge is installed inside the second pitot tube to measure the total pressure of the airflow.

[0013] Optionally, the first clamping member includes a first clamping rod and a second clamping rod tenoned to the first clamping rod. After the first clamping rod and the second clamping rod are tenoned together, a clamping hole for clamping the Pitot tube is formed. A structural groove is provided at the connection between the output end of the airflow generating device and the particle accumulation device. The first clamping rod and the second clamping rod are embedded in the structural groove.

[0014] This invention also provides a method for testing a particle bed, comprising: heating the particle bed using a heating device; measuring the temperature of the particle bed using a temperature measuring device until the particle temperature reaches a set test temperature; if the temperature is below the set temperature, measuring the wind speed near the first end face of the particle bed using a wind speed measuring device, and adjusting an airflow generator to allow airflow to pass through the particle bed in the particle bed at a predetermined wind speed, while simultaneously measuring the wind pressure inside the particle bed using a wind pressure measuring device, and measuring the temperature of the particle bed using a temperature measuring device; if the temperature is above the set temperature, supplying airflow to the particle bed in the particle bed using an airflow generator to cool it down until the temperature of the particle bed measured by the temperature measuring device is below the set temperature; and analyzing the heat conduction and heat transfer characteristics of the particles based on the wind pressure and temperature of the particle bed at the predetermined wind speed.

[0015] The particle packing bed test bench and its test method provided by the present invention have the following beneficial effects:

[0016] Because the first end face of the particle stacking device connected to the output end of the airflow generating device and the second end face opposite to the first end face are hollowed out, the particle stacking device has a stacking cavity for granular material stacking. The first end face and the second end face of the particle stacking device are respectively connected to the stacking cavity. Therefore, the airflow generated by the airflow generating device can enter the stacking cavity through the first end face and then exit from the stacking cavity through the second end face, thereby providing airflow for the granular material in the stacking cavity. Because the sampling end of the temperature measuring device is inserted into the stacking cavity, the temperature of the granular material can be collected when the airflow passes through or under natural conditions. The wind pressure measuring device collects the wind pressure near the first and second end faces of the stacking cavity, so the wind pressure flowing through the granular material can be calculated, thereby calculating the heat transfer coefficient of the granular material. The wind speed measuring device collects the wind speed near the first end face of the stacking cavity, so the influence of different wind speeds on the heat transfer and thermal conductivity of the granular material can be measured. Because the temperature of the granular material under different wind pressures and wind speeds can be monitored, it is convenient to... This invention establishes temperature variation diagrams for different particulate matter under varying wind pressures and velocities, facilitating the calculation of bulk cargo equipment temperatures. Compared to existing technologies that focus on the heat transfer performance of high-temperature heat pipes, this invention evaluates their application performance in chemical, aerospace, and nuclear energy fields by measuring parameters such as inner and outer wall temperatures and heat flux densities. It employs a steady-state method to measure the thermal conductivity of bulk materials; measures the thermal conductivity of mixed gases using a constant-volume gas heat transfer power detection method; measures the convective heat transfer coefficient of a flat plate surface using a symmetrical heating and double-sided airflow method; studies the flow and heat transfer characteristics of carbon dioxide under different operating conditions, measuring relevant parameters through a sleeve structure to calculate heat transfer and resistance coefficients; and studies the flow and heat transfer characteristics of particle-packed beds, primarily measuring the pressure, temperature, and flow rate of the working fluid. This comprehensive test bench covers various heat transfer scenarios, from solids to gases, and from simple geometries to complex structures. In this embodiment, the test bench studying the heat conduction and transfer laws between particles can more accurately calculate the heat transfer and orientation of particulate matter, thereby more accurately calculating the temperature of bulk cargo equipment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the particle-stacking bed test bench in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the airflow generating device, heating device, particle stacking device, temperature measuring device, wind pressure measuring device, and wind speed measuring device of the particle stacking bed test bench in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the airflow generating device, heating device, particle stacking device, temperature measuring device, wind pressure measuring device, and wind speed measuring device of the particle stacking bed test bench in another perspective of the present invention.

[0020] Figure 4 This is a schematic diagram of the heating device, particle stacking device, temperature measuring device, wind pressure measuring device and wind speed measuring device of the particle stacking bed test bench in an embodiment of the present invention.

[0021] Figure 5 This is a partial structural schematic diagram of the heating device, particle stacking device, temperature measuring device, wind pressure measuring device, and wind speed measuring device of the particle stacking bed test bench in an embodiment of the present invention.

[0022] Figure 6 This is a partial structural schematic diagram of the wind pressure measuring device of the particle packing bed test bench in an embodiment of the present invention;

[0023] Figure 7 This is a partial structural schematic diagram of the wind pressure measuring device of the particle stacked bed test bench in another perspective of an embodiment of the present invention.

[0024] Figure 8 This is a schematic diagram of the structure of the first clamping component of the wind pressure measuring device of the particle bed test bench in this embodiment of the invention;

[0025] Figure 9 This is a schematic diagram of the structure of the first clamping member of the wind speed measuring device of the particle stacked bed test bench in an embodiment of the present invention, which clamps the first Pitot tube.

[0026] Figure 10 This is a schematic diagram of the distribution of thermocouple probes in an embodiment of the present invention;

[0027] Figure 11 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated at 100°C in an embodiment of the present invention.

[0028] Figure 12 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated to 200°C in an embodiment of the present invention.

[0029] Figure 13 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated to 300°C in an embodiment of the present invention.

[0030] Figure 14 This is the temperature curve of 6mm diameter zirconia ceramic particles in an embodiment of the present invention when heated at 300°C;

[0031] Figure 15 This is the temperature curve of 12mm diameter zirconia ceramic particles when heated to 300°C in an embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 100-Support frame; 110-Base frame; 120-First support partition; 130-Second support partition; 200-Airflow generator; 210-Centrifugal fan; 220-Ventilation duct; 230-Rectifier; 231-Partition; 300-Heating device; 500-Wind pressure measuring device; 510-First Pitot tube; 520-Second Pitot tube; 530-First clamping element; 531-First clamping rod; 532-Second clamping rod; 533-Clamping hole; 540-Second clamping element; 541-First clamping block; 542-Second clamping block; 543-Fastener; 600-Wind speed measuring device; 610-First anemometer; 620-Second anemometer; 700-Particle accumulation device; 710-First end face; 720-Second end face; 730-Accumulation cavity; 740-Base plate; 760-Cover plate; 770-Side plate; 780-Mounting hole; 790-Grid plate. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0038] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 , Figure 1 This is a schematic diagram of the overall structure of the particle-stacking bed test bench in an embodiment of the present invention. Figure 2 This is a schematic diagram of the airflow generating device 200, heating device 300, particle stacking device 700, temperature measuring device, wind pressure measuring device 500, and wind speed measuring device 600 of the particle stacking bed test bench in an embodiment of the present invention. Figure 3 This is a schematic diagram of the airflow generating device 200, heating device 300, particle stacking device 700, temperature measuring device, wind pressure measuring device 500, and wind speed measuring device 600 of the particle stacking bed test bench in another perspective of this invention. Figure 4 This is a schematic diagram of the heating device 300, particle stacking device 700, temperature measuring device, wind pressure measuring device 500, and wind speed measuring device 600 of the particle stacking bed test bench in this embodiment of the invention. Figure 5 This is a partial structural schematic diagram of the heating device 300, particle stacking device 700, temperature measuring device, wind pressure measuring device 500, and wind speed measuring device 600 of the particle stacking bed test bench in an embodiment of the present invention. Figure 6 This is a partial structural schematic diagram of the wind pressure measuring device of the particle packing bed test bench in one view of an embodiment of the present invention. Figure 7 This is a partial structural schematic diagram of the wind pressure measuring device of the particle bed test bench in another embodiment of the present invention. Figure 8 This is a schematic diagram of the structure of the first clamping component of the wind pressure measuring device of the particle bed test bench in an embodiment of the present invention. Figure 9 This is a schematic diagram of the structure of the first clamping member of the wind speed measuring device of the particle bed test bench in this embodiment of the invention, which clamps the first Pitot tube. This embodiment provides a particle bed test bench, including a support frame 100, an airflow generating device 200, a heating device 300, a temperature measuring device, a wind pressure measuring device 500, a wind speed measuring device 600, and a particle stacking device 700 having a stacking cavity 730 for particle stacking. The airflow generating device 200, the heating device 300, and the particle stacking device 700 are disposed on the support bed, and the particle stacking device 700 is connected to the output end of the airflow generating device 200. The first end face 710 and the second end face 720 opposite to the first end face 710 are hollowed out. The first end face 710 and the second end face 720 are respectively connected to the accumulation cavity 730. The bottom of the particle accumulation device 700 is provided with a heating window. The heating device 300 is embedded in the heating window. The collecting end of the temperature measuring device is inserted into the accumulation cavity 730. The wind pressure measuring device 500 collects the wind pressure of the accumulation cavity 730 near the first end face 710 and the second end face 720. The wind speed measuring device 600 collects the wind speed of the accumulation cavity 730 near the first end face 710.

[0041] Because the first end face 710 of the particle accumulation device 700, which is connected to the output end of the airflow generating device 200, and the second end face 720, which is opposite to the first end face 710, are hollowed out, the particle accumulation device 700 has an accumulation cavity 730 for accumulating particles. The first end face 710 and the second end face 720 of the particle accumulation device 700 are respectively connected to the accumulation cavity 730. Therefore, the airflow generated by the airflow generating device 200 can enter the accumulation cavity 730 through the first end face 710, and then exit from the accumulation cavity 730 through the second end face 720, thereby providing a storage space for the accumulation cavity. The particles within 730 provide airflow; since the temperature measuring device's acquisition end is inserted within the accumulation cavity 730, the temperature of the particles can be collected when airflow passes through or under natural conditions (without additional airflow); the wind pressure measuring device 500 collects the wind pressure near the first end face 710 and the second end face 720 of the accumulation cavity 730, thus allowing the calculation of the wind pressure flowing through the particles, and consequently, the calculation of the particles' heat transfer coefficient; the wind speed measuring device 600 collects the wind speed near the first end face 710 of the accumulation cavity 730, thus allowing the measurement of different wind speeds. The impact on the heat transfer and thermal conductivity of particulate matter; since the temperature of particulate matter can be monitored under different wind pressures and velocities, it is easy to establish temperature change maps of different particulate matter under different wind pressures and velocities, thus facilitating the calculation of the temperature of bulk cargo equipment. Compared with existing technologies that focus on the heat transfer performance of high-temperature heat pipes, this method evaluates its application performance in chemical, aerospace, and nuclear energy fields by measuring parameters such as inner and outer wall temperatures and heat flux densities. The thermal conductivity of bulk materials is measured using a steady-state method; for the thermal conductivity of mixed gases, a constant-volume gas heat transfer power detection method is used for measurement. The convective heat transfer coefficient of the plate surface is studied using a symmetrical heating and double-sided air blowing method to investigate the flow and heat transfer characteristics of carbon dioxide under different operating conditions. Relevant parameters are measured through a sleeve structure to calculate the heat transfer and resistance coefficients, and the flow and heat transfer characteristics of the particle bed are studied. However, the pressure, temperature and flow rate of the working fluid are mainly measured. The test bench covers a variety of heat transfer scenarios from solid to gas and from simple geometry to complex structure. In this embodiment, the test bench for studying the heat conduction and heat transfer laws between particles can more accurately calculate the heat transfer and orientation of particles, thereby more accurately calculating the temperature of bulk cargo equipment.

[0042] The airflow generating device 200 includes a centrifugal fan 210 and a ventilation duct 220. The output end of the centrifugal fan 210 is connected to the input end of the ventilation duct 220, and the output end of the ventilation duct 220 is connected to the first end face 710 of the particle accumulation device 700. In this way, the high-pressure airflow from the centrifugal fan 210 can be sent into the accumulation chamber 730 through the ventilation duct 220.

[0043] Preferably, the airflow generating device 200 further includes a rectifier 230 for converting irregularly flowing high-pressure airflow into regularly flowing high-pressure airflow. The input end of the rectifier 230 is connected to the output end of the ventilation pipe 220, and the output end of the rectifier 230 is connected to the first end face 710 of the particle accumulation device 700. Thus, the rectifier 230 can convert the airflow entering the accumulation chamber 730 into a regular and uniform airflow, thereby improving the accuracy of the experiment.

[0044] refer to Figure 3 The rectifier 230 includes a rectifier box with openings at both ends and a plurality of baffles 231. The two openings of the rectifier box are respectively connected to the output end of the ventilation pipe 220 and the input end of the particle accumulation device 700. The plurality of baffles 231 are horizontally arranged and evenly distributed in the rectifier box. The two ends of the baffles 231 are respectively connected to the two side walls of the rectifier box.

[0045] The particle stacking device 700 includes a base plate 740, a cover plate 760, two side plates 770, and two grid plates 790. The two side plates 770 are respectively disposed opposite to each other on the base plate 740, and the two grid plates 790 are respectively disposed opposite to each other on the base plate 740, with the side plates 770 perpendicular to the grid plates 790. The cover plate 760 covers the two side plates 770 and the two grid plates 790. The base plate 740, the cover plate 760, the two side plates 770, and the two grid plates 790 form the stacking cavity 730. One grid plate 790 has a first end face 710, and the other grid plate 790 has a second end face 720. A heating window is provided on the base plate 740.

[0046] The base plate 740, the cover plate 760, and the two side plates 770 are all made of mica. Because mica has excellent high-temperature resistance and thermal insulation properties, it ensures that the test accuracy remains even when the test temperature reaches above 800℃.

[0047] Specifically, the cover plate 760 and the side plate 770 are connected by angle iron, and the angle iron is fixed to the side plate 770 and the cover plate 760 by screws.

[0048] The support frame 100 includes a base frame 110 and a first support partition 120 and a second support partition 130 spaced apart on the base frame 110. The heating device 300 is disposed on the base frame 110. The base plate 740 is disposed on the first support partition 120 and the second support partition 130. The heating device 300 is located between the first support partition 120 and the second support partition 130 and is located below the base plate 740.

[0049] The heating device 300 includes a heating plate. When the heating plate is energized, it generates heat that is transferred to the particle packing bed.

[0050] The temperature measuring device includes multiple thermocouples, each thermocouple comprising a thermocouple probe and a temperature display for showing the temperature information collected by the thermocouple probe. The particle stacking device 700 (side plate 770) has multiple mounting holes 780, and the thermocouple probes are installed within these mounting holes 780. As a high-precision, fast-response temperature measuring device, the thermocouples can be used to measure the temperature of particles at different locations within a particle stacking bed and record the data.

[0051] Preferably, the mounting holes 780 are distributed at different heights on the particle stacking device 700 (side plate 770).

[0052] The wind speed measuring device 600 includes a first anemometer 610, which is installed on the side of the particle accumulation device 700 near the airflow generating device 200 and partially located within the accumulation cavity 730. Thus, the first anemometer 610 can measure the wind speed entering the particle accumulation device 700 from the airflow generating device 200.

[0053] Preferably, the wind speed measuring device 600 further includes a second anemometer 620, which is installed on the side of the particle accumulation device 700 away from the airflow generating device 200 and is partially located within the accumulation chamber 730. This improves the accuracy of wind speed detection and facilitates the determination of whether airflow passes through the particle accumulation bed, making testing easier.

[0054] The wind pressure measuring device 500 includes a first pitot tube 510, a second pitot tube 520, a first clamping member 530, a second clamping member 540, a first barometer, and a second barometer. The first clamping member 530 is mounted on the particulate matter accumulation bed. The first pitot tube 510 is mounted on the first clamping member 530 and extends into the accumulation cavity 730 on the side near the airflow generating device 200. The first barometer is installed inside the first pitot tube 510 to measure the total airflow pressure. The second clamping member 540 is mounted on the particulate matter accumulation bed. The second pitot tube 520 is mounted on the second clamping member 540 and extends into the accumulation cavity 730 on the side away from the airflow generating device 200. The second barometer is installed inside the second pitot tube 520 to measure the total airflow pressure. The pitot tube has two openings: one facing the airflow direction (windward opening), and one parallel to or slightly oblique to the airflow direction (leeward opening). When the rectified, regular airflow passes through the windward inlet of the pitot tube, it slows down or even stops due to obstruction, thus allowing the measurement of the total air pressure. When passing through the leeward inlet, the static pressure of the airflow is measured. A first barometer connected to the first pitot tube 510 extracts a pressure signal from the airflow within the first pitot tube 510 via a pressure tapping tube. This signal is converted into a first electrical signal or other measurable first physical quantity by a sensor. A second barometer connected to the second pitot tube 520 extracts a pressure signal from the airflow within the second pitot tube 520 via a pressure tapping tube. This signal is converted into a second electrical signal or other measurable second physical quantity by a sensor. Then, the difference between the first and second electrical signals, or the difference between the first and second physical quantities, is calculated and converted into wind pressure. Finally, this value is displayed on the screen as the measured airflow pressure value.

[0055] The first clamping member 530 includes a first clamping rod 531 and a second clamping rod 532 that is tenoned with the first clamping rod 531. After the first clamping rod 531 and the second clamping rod 532 are tenoned together, a clamping hole 533 for clamping the Pitot tube is formed. A structural groove is provided at the connection between the output end of the airflow generating device 200 and the particle accumulation device 700. The first clamping rod 531 and the second clamping rod 532 are embedded in the structural groove.

[0056] The second clamping member 540 includes a first clamping block 541, a second clamping block 542, and a fastener 543 detachably and fixedly mounted on the particle stacking device 700. The first clamping block 541 and the second clamping block 542 cooperate to form a mounting through hole for clamping the second Pitot tube 520. The first clamping block 541 has a first through hole, and the second clamping block 542 has a second through hole. The fastener passes through the first through hole and the second through hole to lock the first clamping block 541 and the second clamping block 542 together.

[0057] In this embodiment, when the centrifugal fan 210 is turned on, the regular airflow passes through the particle bed and then through the first grid plate 790. The airflow velocity after passing through the particle bed can be measured by the first anemometer 610 on the side plate 770. The final air pressure of the airflow after passing through the particle bed is measured by the first pressure gauge and the second pressure gauge. The temperature of the particles inside the particle bed is measured by the thermocouple. The airflow velocity, pressure, and temperature are recorded to obtain the comprehensive transfer law of contact heat conduction between particles and convective heat transfer between particles and interstitial air. If the centrifugal fan 210 is turned off, the test bench will switch to studying the comprehensive law of contact heat conduction between particles under natural ventilation conditions. Under this condition, the centrifugal fan 210 does not generate airflow. The loose particles in the particle bed are heated by the heating plate, and there is contact heat conduction between the particles. The temperature between particles at different locations is measured by the thermocouple, and then the contact heat conduction law between particles is analyzed.

[0058] This embodiment also provides a method for testing a particle-packed bed, including:

[0059] The particle bed is heated by heating device 300;

[0060] The temperature of the particle accumulation is measured by a temperature measuring device until the particle temperature reaches the set test temperature. If the temperature is below the set temperature, the wind speed near the first end face 710 of the particle accumulation bed is measured by a wind speed measuring device 600, and the airflow generating device 200 is adjusted to make the airflow pass through the particle accumulation bed in the particle accumulation device 700 at a predetermined wind speed. At the same time, the wind pressure measuring device 500 measures the wind pressure in the particle accumulation bed, and the temperature of the particle accumulation bed is measured by a temperature measuring device. If the temperature is above the set temperature, the airflow generating device 200 delivers airflow to the particle accumulation bed in the particle accumulation device 700 to cool it down until the temperature of the particle accumulation bed is measured by the temperature measuring device to be below the set temperature.

[0061] The heat conduction and heat transfer characteristics of particles are analyzed based on the wind pressure and temperature of the particle packing bed at a predetermined wind speed.

[0062] Specifically, taking experimental data of 12mm diameter zirconia ceramic particles under natural convection as an example, we explored the heat conduction and heat transfer characteristics of the particles.

[0063] This experiment employed a controlled variable method and a grouped experimental approach. A temperature controller was used to adjust the temperature of the heating plate, heating particle beds of the same size and material to different temperatures. Thermocouples were used to record the temperature changes at various measuring points on the particle bed in real time. (Reference) Figure 10 , Figure 10This is a schematic diagram of the thermocouple probe distribution in an embodiment of the present invention. Four thermocouple probes above the heating plate, four thermocouple probes on the side of the heating plate, and four thermocouple probes arranged obliquely upwards are selected sequentially as the vertical axis. The heating time of the zirconia ceramic particles at the corresponding temperature is used as the horizontal axis to create isotherm cloud maps of 12mm diameter zirconia ceramic particles. Isotherm cloud maps of zirconia ceramic particles heated at 100°C, 200°C, and 300°C are obtained respectively. Figure 11 , Figure 12 and Figure 13 , Figure 11 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated to 100°C in an embodiment of the present invention. Figure 12 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated to 200°C in an embodiment of the present invention. Figure 13 This is an isotherm cloud diagram of 12mm diameter zirconia ceramic particles heated to 300°C in an embodiment of the present invention.

[0064] observe Figure 11 , Figure 12 and Figure 13 It can be observed that as the temperature increases, the oblique high-temperature region changes from CH1-CH3 to CH1-CH2, indicating that the natural convection activity of the zirconia particles decreases with increasing temperature. At 100℃, the temperature difference between the CH2 and oblique CH1 measuring points on the plate is 22.4℃; at 200℃, the temperature difference is 80℃; and at 300℃, the temperature difference is 108.7℃. Simultaneously, at 100℃, the temperature difference between CH2 on the plate and CH2 at the plate edge is 44.2℃; at 200℃, the temperature difference is 123.4℃; and at 300℃, the temperature difference is 166.5℃. This indicates that while the heat transfer rate of the zirconia particles increases with increasing temperature, the heat transfer is insufficient, and natural convection is not very active. Meanwhile, it can be observed that when 12mm diameter zirconia particles are heated to 100℃, it takes 647s to reach 35℃ at the oblique CH1 measuring point, 768s to reach 200℃, and 661s to reach 300℃. This indicates that in the region near the heat source, the heat transfer rate of zirconia particles is not significantly affected by temperature changes.

[0065] To investigate the effect of particle size on natural convection in a particle bed, particles of the same material were divided into two groups based on their size: 6 mm and 12 mm. Both groups were heated to the same temperature, and the temperature at each measuring point was recorded in real time. The obtained temperature data was then plotted as a dot-line graph, as shown below. Figure 14 and Figure 15 , Figure 14 This is the temperature curve of 6mm diameter zirconia ceramic particles in an embodiment of the present invention when heated to 300°C. Figure 15This is the temperature curve of 12mm diameter zirconia ceramic particles when heated to 300°C in an embodiment of the present invention.

[0066] observe Figure 14 and Figure 15 It can be observed that when the heating plate is set to 300℃ and heated to a steady state, the temperature difference between the CH2 measuring point on the plate and the CH2 measuring point on the edge of the 6mm particle bed is 174.5℃, while the temperature difference at the same measuring point for the 12mm particle group is 166.5℃, indicating that the horizontal convection of the larger particle group is more sufficient. Furthermore, the temperature difference between the CH2 measuring point on the plate and the inclined CH1 measuring point on the 6mm particle bed is 133.8℃, while the temperature difference at the measuring point for the 12mm particle group is 108.7℃, indicating that due to the higher porosity, the vertical natural convection of the larger particle group is more sufficient than that of the smaller particle group. Simultaneously, it can be observed that the temperature difference between the CH2 measuring point on the edge of the 6mm particle bed and the inclined CH4 measuring point is 45.9℃, while the temperature difference at the measuring point for the 12mm particle group is 49.1℃, indicating that the convection of the 6mm particle bed is more sufficient in the area away from the heat source.

[0067] When heated to a steady state, the highest temperature of the 6mm particle size was 245.2℃, while the highest temperature of the 12mm particle size was 252.2℃. The temperature of the 6mm particle size group rose more slowly than that of the 12mm particle size group, indicating that the thermal conductivity of the large-diameter particle bed is higher than that of the small-diameter particle bed. Furthermore, due to the increase in temperature, the Grashof number increases, the Prandtl number does not change much, the Rayleigh number increases, and the laminar flow changes to turbulent flow. The resulting vortices make the horizontal and vertical heat transfer inside the large-diameter particle bed more complete. Therefore, the highest temperature of the large-diameter particles is higher.

[0068] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A granular packed bed test method characterized by, A particle stacking bed test bench is used, which includes a support frame and a particle stacking bed. The particle stacking bed includes an airflow generating device, a heating device, a temperature measuring device, a wind pressure measuring device, a wind speed measuring device, and a particle stacking device with a stacking cavity for particle stacking. The airflow generating device, the heating device, and the particle stacking device are mounted on the support bed. The first end face of the particle stacking device connected to the output end of the airflow generating device and the second end face opposite to the first end face are hollowed out. The first end face and the second end face are respectively connected to the stacking cavity. A heating window is opened at the bottom of the particle stacking device, and the heating device is embedded in the heating window. The collecting end of the temperature measuring device is inserted into the stacking cavity. The wind pressure measuring device collects the wind pressure of the stacking cavity near the first end face and the second end face. The wind speed measuring device collects the wind speed of the particle stacking device on the side near the airflow generating device and the wind speed of the particle stacking device away from the airflow generating device. The wind pressure measuring device includes a first pitot tube, a second pitot tube, a first clamping member, a second clamping member, a first barometer, and a second barometer. The first clamping member is installed on the particulate matter accumulation bed. The first pitot tube is installed on the first clamping member and extends into the accumulation cavity on the side near the airflow generating device. The first barometer is installed inside the first pitot tube to measure the total pressure of the airflow. The second clamping member is installed on the particulate matter accumulation bed. The second pitot tube is installed on the second clamping member and extends into the accumulation cavity on the side away from the airflow generating device. The second barometer is installed inside the second pitot tube to measure the total pressure of the airflow. The specific steps are as follows: The particle bed is heated using a heating device; the temperature of the particle bed is measured using a temperature measuring device until the temperature reaches the set test temperature. If the temperature is below the set temperature, the wind speed near the first end face of the particle bed is measured using a wind speed measuring device, and the airflow generator is adjusted to allow airflow to pass through the particle bed at a predetermined wind speed. Simultaneously, the wind pressure inside the particle bed is measured using a wind pressure measuring device, and the temperature of the particle bed is measured using a temperature measuring device. If the temperature is above the set temperature, airflow is supplied to the particle bed in the particle bed through the airflow generator to cool it down until the temperature of the particle bed is measured to be below the set temperature. The heat conduction and heat transfer characteristics of particles are analyzed based on the wind pressure and temperature of the particle packing bed at a predetermined wind speed.

2. A granular packed bed test method according to claim 1, characterised in that, The airflow generating device includes a centrifugal fan and a ventilation duct. The output end of the centrifugal fan is connected to the input end of the ventilation duct, and the output end of the ventilation duct is connected to the first end face of the particle accumulation device.

3. The particle packing bed test method according to claim 2, characterized in that, The airflow generating device further includes a rectifier for converting irregularly flowing high-pressure airflow into regularly flowing high-pressure airflow. The input end of the rectifier is connected to the output end of the ventilation pipe, and the output end of the rectifier is connected to the first end face of the particle accumulation device.

4. The granular packing bed test method of claim 1, wherein, The particle stacking device includes a base plate, a cover plate, two side plates, and two grid plates. The two side plates are respectively disposed opposite to each other on the base plate, and the two grid plates are respectively disposed opposite to each other on the base plate. The side plates are perpendicular to the grid plates. The cover plate covers the two side plates and the two grid plates. The base plate, the cover plate, the two side plates, and the two grid plates form the stacking cavity. One grid plate has a first end face, and the other grid plate has a second end face. A heating window is provided on the base plate.

5. The particle packing bed test method according to claim 4, characterized in that, The base plate, the cover plate, and the two side plates are all made of mica.

6. The granular packed bed test method of claim 1, wherein, The temperature measuring device includes multiple thermocouples, each thermocouple including a thermocouple probe and a temperature display for displaying the temperature information collected by the thermocouple probe. The particle stacking device has multiple mounting holes, and the thermocouple probe is installed in the mounting holes.

7. The granular packed bed testing method of claim 1, wherein, The wind speed measuring device includes a first anemometer, which is installed on the side of the particle accumulation device close to the airflow generating device and is partially located inside the accumulation cavity; the wind speed measuring device also includes a second anemometer, which is installed on the side of the particle accumulation device away from the airflow generating device and is partially located inside the accumulation cavity.

8. The granular packed bed test method of claim 1, wherein, The first clamping member includes a first clamping rod and a second clamping rod that is tenoned to the first clamping rod. After the first clamping rod and the second clamping rod are tenoned together, a clamping hole for clamping the first Pitot tube is formed. A structural groove is provided at the connection between the output end of the airflow generating device and the particle accumulation device. The first clamping rod and the second clamping rod are embedded in the structural groove.

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