Heat conduction disc for combined determination of shear stress and heat transfer performance of high-viscosity fluid, combined determination device and combined determination method

Abstract

The invention discloses a heat conduction disc, a combined measurement device and a combined measurement method for combined measurement of shear stress and heat transfer performance of a high-viscosity fluid. The heat conduction disc is provided with temperature measurement equipment holes which are distributed in an axial symmetry manner and are used for mounting temperature measurement equipment; the combined measuring device comprises a heat conduction disc, a torque sensor, a torque sensor control system, a distance sensor, a distance sensor control system, a mechanical lifting mechanism, a thermocouple, a temperature recording system, a heating film, a temperature controller and a support, and the distance sensor can feed back the height position of a lifting platform of the mechanical lifting mechanism in real time. A heating film and a heat conduction disc embedded with a thermocouple are sequentially arranged on a lifting platform of the mechanical lifting mechanism in a stacked mode, the thermocouple embedded in a hole of the temperature measuring device upwards extends out of the heat conduction disc, and a torque sensor suspended on a support is arranged over the heat conduction disc. The combined measuring device provided by the invention can be used for carrying out combined testing on the shear stress and the heat transfer coefficient of the high-viscosity fluid.

Description

Technical Field

[0001] The invention belongs to the technical field of fluid shear and heat transfer joint measurement, and specifically relates to a heat conducting plate, a joint measurement device and a joint measurement method for joint measurement of shear stress and heat transfer performance of high-viscosity fluid. Background Art

[0002] High viscosity fluid refers to fluid with viscosity more than two orders of magnitude higher than water, which is widely used in industrial processes such as wind power lubrication, oil extraction, polymer processing and bio-fermentation. With the increasing development of science and technology and the increasing prominence of energy problems, the related research on heat transfer enhancement technology has become an important research field. In recent years, the enhancement of heat transfer of high viscosity fluids by regulating interfacial shear stress has attracted widespread attention from many scholars, and the related theory of heat transfer enhancement technology has developed rapidly. However, since high viscosity fluids have lower heat transfer efficiency and slower heat conduction rate than low viscosity fluids, they are prone to flow instability and decreased heat transfer performance during the flow process, resulting in higher energy consumption costs during the heat conduction process. Studies have found that surface wettability has an important influence on the heat transfer performance of high viscosity fluids. Some scholars have found that wettability significantly increases the feed flow rate on the membrane surface, significantly improves the heat transfer coefficient, and thus greatly increases the permeation flux. For the surface of superhydrophobic membranes, the roughness accounts for less than 1% of the total heat transfer coefficient. Surface treatment technology can be used to optimize material design, improve the shear stress distribution between the interface and the high-viscosity fluid, increase heat transfer efficiency, and reduce thermal resistance, thereby enhancing the system's thermal management capabilities and reducing energy costs. The determination of the shear stress of the fluid on the solid modified surface indicates the degree of shear stress regulation, while the heat transfer coefficient [K]_i measures the intensity of the heat transfer process. Therefore, the joint determination of shear stress and heat transfer coefficient has also become an important parameter in the field of interfacial shear stress regulation and enhanced heat transfer.

[0003] For the test of the enhanced heat transfer performance of high-viscosity fluids, the determination of their heat transfer coefficient is crucial, and the size of the heat transfer coefficient directly determines the strength of the enhanced performance. The fluid at the boundary layer is usually static. Can the non-Newtonian fluid at the boundary layer produce slip by regulating the interface shear stress, achieve disturbance at the boundary layer, and then enhance the heat transfer? In recent years, some scholars have regulated the shear stress on the inner wall of the circular tube, and conducted a qualitative analysis of the heat transfer performance of the high-viscosity Casson fluid in it through numerical simulation. It is found that with the increase of the slip length, its heat transfer coefficient is greatly improved; some scholars have regulated the shear stress on the surface of the wedge-shaped body, and found through numerical calculation that the heat transfer coefficient of the high-viscosity Carlo fluid has not increased significantly; some scholars have studied the heat transfer of 0.5% polyethylene oxide solution, a high-viscosity fluid, through model calculation, and found that regulating the interface shear stress weakens its heat transfer performance. Therefore, regulating the shear stress and the interface of different wettability to cause the fluid to slip may lead to three different effects: enhanced heat transfer, insignificant heat transfer, and weakened heat transfer. How to match shear stress, surfaces with different wettability and high viscosity fluids to achieve the best enhanced heat transfer effect for high viscosity fluids.

[0004] Existing research on interfacial shear stress regulation to enhance heat transfer is widely based on the study of ideal systems through numerical simulation, which is difficult to apply to complex situations in practical applications. At the same time, the regulation of interfacial shear stress has not been quantified, and it is impossible to determine the regulation range of interfacial shear stress that can enhance heat transfer. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the prior art and to provide a heat conducting plate, a combined measuring device and a combined measuring method for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid. The combined measuring method can better reflect the correlation between regulating the interfacial shear stress and the enhanced heat transfer of the high-viscosity fluid by jointly measuring the shear flow and heat transfer performance of the high-viscosity fluid on the solid surface.

[0006] The purpose of the present invention is to be solved by the following technical solutions:

[0007] A heat conducting plate for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid, characterized in that: the diameter D and thickness H of the cylindrical heat conducting plate satisfy D / H=10-20, a plurality of axisymmetrically distributed temperature measuring device holes are arranged in the heat conducting plate, the temperature measuring device holes arranged through the heat conducting plate are used to install the temperature measuring device, and the size and quantity of the temperature measuring device and the temperature measuring device holes match each other.

[0008] The material of the heat conducting plate includes aluminum, iron, copper, titanium, stainless steel, diamond-like carbon, titanium nitride and tungsten carbide.

[0009] The diameter D of the heat conducting plate is 10 mm to 100 mm, the thickness H is 1 mm to 5 mm, and the diameter d of the temperature measuring device hole is T It is 0.2mm~1mm.

[0010] At least one wiring groove is formed at the bottom of the heat conducting plate, and a signal line between the temperature measuring device installed in the temperature measuring device hole and the temperature recording system is arranged in the wiring groove.

[0011] The wiring groove is arranged along the radial direction of the heat-conducting plate and runs through the bottom of the heat-conducting plate; the central axis of the temperature measuring device hole is located at the vertex of the wiring groove.

[0012] The wiring groove is a semicircular groove, the diameter d of the semicircular groove is 1mm-5mm, the length D is 10mm-100mm, and D / d=10-20.

[0013] The temperature measuring device holes are arranged along the wiring grooves, and N holes with equal spacing of δ are arranged on the same wiring groove. T The temperature measuring device hole at this time, the distance from the center of the temperature measuring device hole closest to the outer edge of the heat conducting plate to the outer edge of the heat conducting plate is δ T-S , then N, δ T ,δ T-S Satisfy D=2δ T-S +(N-1)×δ T , and the spacing is equal to δ T Satisfy δ T / D≥0.25.

[0014] A combined measuring device comprises a heat conducting plate, a torque sensor and a torque sensor control system connected to its circuit, a distance sensor and a distance sensor control system connected to its circuit, a mechanical lifting mechanism, a thermocouple as a temperature measuring device and a temperature recording system connected to its circuit, a heating film and a temperature controller connected to its circuit, and a bracket. The distance sensor is arranged below a lifting platform of the mechanical lifting mechanism to provide real-time feedback on the height position of the lifting platform. A heating film and a heat conducting plate embedded with a thermocouple are sequentially stacked on the lifting platform of the mechanical lifting mechanism. The thermocouple is embedded in a hole of the temperature measuring device, and the upper edge of the thermocouple protrudes from the upper edge of the heat conducting plate, and the lower edge of the thermocouple is located in the heat conducting plate. A torque sensor suspended on the bracket is arranged directly above the heat conducting plate. The upper surface area of ​​the lifting platform, the surface area of ​​the heating film and the area of ​​the heat conducting plate are the same. A high-viscosity fluid placed on the heat conducting plate can immerse the upper edge of the thermocouple, and the upper edge of the high-viscosity fluid can fit the bottom of the upper surface of the lifting platform under the action of the mechanical lifting mechanism.

[0015] The combined measuring device also includes a motor, which is connected to the distance sensor control system through a line and is controlled by the distance sensor control system. The motor is connected to the mechanical lifting mechanism through a transmission shaft to input lifting power.

[0016] The torque sensor can control and set the shear rate, and obtain the torque M of the high-viscosity fluid through the torque sensor.

[0017] The linked distance sensor control system and the distance sensor control the height position of the lifting platform of the mechanical lifting mechanism through the motor to adjust the thickness of the high-viscosity fluid.

[0018] The temperature controller is used to set the heating temperature of the heating film so as to deliver constant heat to the high-viscosity fluid through the heat-conducting disk.

[0019] The temperature recording system records the initial ambient temperature of the experiment and measures and records the real-time temperature T of the high-viscosity fluid through a thermocouple. s .

[0020] The distance from the upper edge of the thermocouple to the upper edge of the high-viscosity fluid is not less than 0.2 mm.

[0021] The heights of the thermocouples on the heat conducting plate increase or decrease in the same diameter direction, and the height difference of the thermocouples in the same diameter direction is not less than 0.2 mm.

[0022] When the thickness of the high viscosity fluid is h g , then the center positions of the N thermocouples on the heat conducting plate satisfy the arrangement spacing at the normal height of the heat conducting plate (h g -0.4mm) / (N-1).

[0023] The thermocouple is a noble / cheap metal thermocouple of model S, R, B, N, K, E, J, T. Before using the thermocouple, it is necessary to perform a 0°C temperature calibration in an ice-water mixture.

[0024] The process of 0°C temperature calibration of the thermocouple is as follows: before embedding the thermocouple into the heat conducting plate, turn on the temperature recording system, insert the thermocouple into the ice-water mixture, and calibrate the thermocouple to 0°C temperature according to the temperature displayed by the temperature recording system.

[0025] The heating film includes polyimide film (PI film), polyurea film (PZT film), polyimide-carbon fiber composite film, zinc oxide film, carbon nanotube film, and the heating temperature range of the heating film is 25-300°C.

[0026] The measurable torque range and corresponding error of the combined measuring device are: 0-100 N·m, ±0.5%, and the measurable shear rate range of the combined measuring device is: 0.01s -1~3600s -1 The shear stress range tested by the combined measuring device is 0.075Pa~1000Pa; the temperature input range of the combined measuring device is 25℃~300℃; the water contact angle range of different surfaces that can be measured by the combined measuring device is: 10°~170°.

[0027] A combined determination method based on a combined determination device, characterized in that the specific steps of the combined determination method are as follows:

[0028] S1. preparing a heat-conducting plate having an upper surface with set wettability;

[0029] S2. Insert the thermocouple connected to the temperature recording system into the corresponding temperature measuring device hole of the heat conducting plate, and adjust the upper edge height of the thermocouple according to the set requirements;

[0030] S3, assembling the heating film of the temperature controller and the heat conducting plate embedded with the thermocouple on the lifting platform of the mechanical lifting mechanism in sequence;

[0031] S4. Place the high-viscosity fluid on the heat-conducting plate and immerse all the thermocouples. The distance sensor control system controls the mechanical lifting mechanism to rise so that the high-viscosity fluid fits the bottom of the torque sensor. The thickness of the high-viscosity fluid is adjusted to 0.5 mm to 3 mm through the linkage of the distance sensor. Different shear rates are set, and the torque M of the high-viscosity fluid is obtained through the torque sensor. The unit is N·m. The temperature controller sets the heating temperature of the heating film and the heating film transmits constant heat to the high-viscosity fluid through the heat-conducting plate. The temperature recording system records the initial ambient temperature of the experiment, and measures and records the real-time temperature T of the high-viscosity fluid at equal time intervals through the thermocouple. s , the unit is ℃;

[0032] S5. The torque M of the high-viscosity fluid obtained by the torque sensor is used to calculate the shear stress τ of the high-viscosity fluid: τ = 2M / (πR 3 ), where the unit of shear stress τ is Pa, R is the disk radius of the torque sensor, and the unit is m; the natural convection heat transfer coefficient of indoor air h is obtained according to the room temperature during the experiment, and the unit is W·m -2 ·K -1 ;

[0033] S6. Based on the natural convection heat transfer coefficient h of indoor air and the temperature rise curve of high viscosity fluid recorded by the temperature recording system, the average heat transfer coefficient of high viscosity fluid is derived.

[0034] The wettable upper surface of the heat conducting plate in step S1 is constructed by electrodeposition, chemical vapor deposition, plasma etching or spraying.

[0035] The specific steps for solving the natural convection heat transfer coefficient h of the indoor air in step S5 are:

[0036] S51. Obtain the Grashof number Gr of the indoor air: Gr = βgρ 2 Φ 3 ΔT / μ 2 , where β is the volume expansion coefficient of indoor air, unit is K -1 , ρ is the indoor air density under the test environment temperature conditions, g is the gravitational acceleration, the value is 9.8m / s 2 , Φ is the characteristic size (i.e., the diameter D of the heat conducting plate), the unit is m, ΔT is the temperature difference between the high viscosity fluid and the initial ambient temperature of the experiment, the unit is K, μ is the viscosity of the indoor air, R is the radius of the torque sensor, the unit is m;

[0037] S52, obtain the Rayleigh number Ra of the indoor air: Ra=GrPr, Pr is the Prandtl number of the indoor air;

[0038] S53. Obtain the Nusselt number Nu of the indoor air: Nu=CRa n , C and n are empirical constants;

[0039] S54. Calculate the natural convection heat transfer coefficient h of indoor air: h = Nuλ / D, where λ is the thermal conductivity of indoor air, in W·m -1 ·K -1 .

[0040] The average heat transfer coefficient of the high viscosity fluid in step S6 The specific solution steps are:

[0041] S61. Calculate the heat dissipation rate Q of the high viscosity fluid to the indoor air during the test a (W): Q a =hA a ΔT, where the heat dissipation rate Q a The unit is W, A a is the total area of ​​heat exchange between high viscosity fluid and indoor air, in m 2 ;

[0042] S62. Calculate the heat absorption rate Q when the temperature of the high viscosity fluid increases c : The heat absorption rate Q c The unit is W, c p is the specific heat capacity of the high viscosity fluid, the unit is J·kg -i ·K -1 , m is the mass of the high viscosity fluid, the unit is kg, is the derivative of the experimental heating temperature;

[0043] S63. Calculate the total heat absorption rate Q of high viscosity fluid s :Q s =Q a +Q c , where the total heat absorption rate Q s The unit is W; S64, calculate the instantaneous heat transfer coefficient K at each moment i :K i =Q s / (A b ΔT1), where A b is the contact area between the high viscosity fluid and the heat source, in m 2 , ΔT1 is the temperature difference between the high viscosity fluid and the heat source, the unit is K;

[0044] S65. Obtain the average heat transfer coefficient of high viscosity fluid Where i is the parameter for the number of high viscosity fluid layers.

[0045] The support is an iron frame.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] The combined measurement device and combined measurement method of the present invention can select surfaces with different hydrophilicity and hydrophobicity, thereby simulating the shear and heat transfer process of actual high-viscosity liquids flowing through different surfaces; the instantaneous heat transfer coefficient can be calculated through the temperature data tested by the thermocouple temperature sensor, so that the degree of heat transfer enhancement of the high-viscosity fluid can be more intuitively seen; the combined measurement method can achieve simple control of interface shear stress regulation by controlling the shear rate; and the combined measurement method can control the fluid temperature by controlling the heating device, so the heat transfer coefficient of the high-viscosity fluid at different temperatures can be measured. Compared with other heat transfer measurements, it has the advantages of less fluid consumption, convenient testing and high testing accuracy.

[0048] The combined measuring device of the present invention conducts a combined test on the interfacial shear stress and heat transfer coefficient of a high-viscosity fluid, provides a thermocouple to measure the temperature change of the high-viscosity fluid during the shear process, and can obtain the effect of different solid interfaces on the heat transfer enhancement of the fluid, promote the mutual verification of the theoretical field of interfacial shear stress regulation and heat transfer enhancement technology and related experiments, and realize the large-scale industrial application of solid interface modification in the enhancement of heat transfer of high-viscosity fluids.

[0049] The combined measuring device and combined measuring method of the present invention can test the viscosity of high viscosity fluid (0.1-50Pa·s) on solid surfaces with different wettability in a large temperature span (20-120°C) and a large shear range (0.01-3600s -1) changes with shear stress regulation, which makes up for the shortcoming that the shear stress and heat transfer coefficient of high-viscosity fluids cannot be measured jointly, and further explores the influence of solid interfaces with different wettability on the heat transfer efficiency of high-viscosity fluids. It not only supplements the deficiencies of existing testing methods, but also provides a complete theoretical basis. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Attached Figure 1 A schematic diagram of the three-dimensional structure of a heat-conducting plate provided by the present invention for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid;

[0051] Attached Figure 2 A schematic diagram of the main structure of a heat conducting plate for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid provided by the present invention;

[0052] Attached Figure 3 A schematic diagram of the top view of the heat conducting plate provided by the present invention for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid;

[0053] Attached Figure 4 A schematic diagram of the side view structure of a heat conducting plate for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid provided by the present invention;

[0054] Attached Figure 5 A schematic diagram of the structure of the combined determination device provided by the present invention;

[0055] Attached Figure 6 The combined determination method provided by the present invention is based on the relationship curve between the interface shear stress regulation factor Re / τ* and the enhanced heat transfer factor E obtained in Example 1, Example 2, Comparative Example 1 and Comparative Example 2.

[0056] Among them: 1—torque sensor; 11—torque sensor control system; 2—distance sensor; 21—motor; 22—distance sensor control system; 23—drive shaft; 24—mechanical lifting mechanism; 3—thermocouple; 31—temperature recording system; 4—heat conducting plate; 41—temperature measuring device hole; 42—wiring groove; 5—heating film; 51—temperature controller; 6—bracket. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0058] like Figure 1-4As shown: a heat conducting plate for jointly measuring the shear stress and heat transfer performance of a high-viscosity fluid, the diameter D and thickness H of the cylindrical heat conducting plate 4 satisfy D / H=10-20, a plurality of temperature measuring device holes 41 are arranged in the heat conducting plate 4 and are symmetrically distributed, the temperature measuring device holes 41 arranged through the heat conducting plate 4 are used to install the temperature measuring device, and the size and number of the temperature measuring device and the temperature measuring device holes 41 match each other; the diameter D of the heat conducting plate 4 is 10mm-100mm, the thickness H is 1mm-5mm, the diameter d of the temperature measuring device hole 41 ... D of the temperature measuring device hole 41 is 10mm-100mm, the thickness H of the temperature measuring device hole 41 is T The thickness of the heat conducting plate 4 is 0.2 mm to 1 mm; the material of the heat conducting plate 4 includes aluminum, iron, copper, titanium, stainless steel, diamond-like carbon, titanium nitride and tungsten carbide.

[0059] When the temperature measuring device arranged on the heat conducting plate 4 needs to be connected by wire, at least one wiring groove 42 is opened at the bottom of the heat conducting plate 4, and the signal line between the temperature measuring device installed in the temperature measuring device hole 41 and the temperature recording system 31 is arranged in the wiring groove 42; the wiring groove 42 is arranged along the radial direction of the heat conducting plate 4 and runs through the bottom of the heat conducting plate 4; the temperature measuring device hole 41 is arranged along the wiring groove 42, and the central axis of the temperature measuring device hole 41 is preferably located at the vertex of the wiring groove 42. When N temperature measuring device holes 41 with equal spacing of δT are arranged on the same wiring groove 42, the center of the temperature measuring device hole 41 closest to the outer edge of the heat conducting plate 4 is δT away from the outer edge of the heat conducting plate 4. T-S , then N, δ T , δ T-S Satisfy D=2δ T-S +(N-1)×δ T , and the spacing is equal to δ T Satisfy δ T / D≥0.25.

[0060] A further preferred solution is that the wiring groove 42 is a semicircular groove, the diameter d of the semicircular groove is 1 mm to 5 mm, the length D is 10 mm to 100 mm, and D / d=10-20.

[0061] like Figure 5As shown: a combined measuring device, the combined measuring device includes a heat conducting plate 4, a torque sensor 1 and a torque sensor control system 11 connected to its circuit, a distance sensor 2 and a distance sensor control system 22 connected to its circuit, a mechanical lifting mechanism 24, a thermocouple 3 as a temperature measuring device and a temperature recording system 31 connected to its circuit, a heating film 5 and a temperature controller 51 connected to its circuit, and a bracket 6. By setting the shear rate and obtaining the torque M of the high-viscosity fluid through the torque sensor 1; the distance sensor 2 is arranged under the lifting platform of the mechanical lifting mechanism 24 to feedback the height position of the lifting platform in real time, and the combined measuring device is used to measure the temperature of the high-viscosity fluid. The distance sensor control system 22 and the distance sensor 2 control the height position of the lifting platform of the mechanical lifting mechanism 24 through the motor 21 to adjust the thickness of the high-viscosity fluid; the heating film 5 and the heat-conducting plate 4 embedded with the thermocouple 3 are sequentially stacked on the lifting platform of the mechanical lifting mechanism 24, the thermocouple 3 is embedded in the temperature measuring device hole 41, and the upper edge of the thermocouple 3 protrudes from the upper edge of the heat-conducting plate 4, and the lower edge of the thermocouple 3 is located in the heat-conducting plate 4, and the torque sensor 1 suspended on the bracket 6 is arranged directly above the heat-conducting plate 4; the temperature recording system 31 records the initial temperature T of the experiment and measures and records the real-time temperature T of the high-viscosity fluid through the thermocouple 3. s The temperature controller 51 is used to set the heating temperature of the heating film 5 so as to deliver constant heat to the high-viscosity fluid through the heat conducting plate 4;

[0062] The upper surface area of ​​the above-mentioned lifting platform, the surface area of ​​the heating film 5 and the area of ​​the heat-conducting disk 4 are the same size. The high-viscosity fluid placed on the heat-conducting disk 4 can immerse the upper edge of the thermocouple 3 and the upper edge of the high-viscosity fluid can fit the bottom of the disk of the torque sensor 1 under the action of the mechanical lifting mechanism 24. At this time, the distance from the upper edge of the thermocouple 3 to the upper edge of the high-viscosity fluid is not less than 0.2 mm.

[0063] On the basis of the above structure, the combined measuring device also includes a motor 21, which is connected to a distance sensor control system 22 through a line and is controlled by the distance sensor control system 22. The motor 21 is connected to a mechanical lifting mechanism 24 through a transmission shaft 23 to input lifting power.

[0064] The thermocouple 3 used in the present invention is a noble / cheap metal thermocouple of type S, R, B, N, K, E, J, T. Before using the thermocouple 3, it is necessary to calibrate the temperature to 0°C in an ice-water mixture. In terms of the layout of the thermocouple 3, the height of the thermocouple 3 on the heat conducting plate 4 increases or decreases in the same diameter direction, and the height difference of the thermocouple 3 in the same diameter direction is not less than 0.2mm; when the thickness of the high-viscosity fluid is h g , then the center positions of the N thermocouples 3 on the heat conducting plate 4 satisfy the arrangement spacing at the normal height of the heat conducting plate 4 (h g -0.4mm) / (N-1).

[0065] In the above structure, the heating film 5 is made of polyimide film (PI film), polyurea film (PZT film), polyimide-carbon fiber composite film, zinc oxide film, or carbon nanotube film, and the heating temperature range of the heating film 5 is required to be 25 to 300°C.

[0066] The measurable torque range and corresponding error of the combined measuring device are: 0-100 N·m, ±0.5%. The measurable shear rate range of the combined measuring device is: 0.01s -1 ~3600s -1 The shear stress range tested by the combined measuring device is 0.075Pa~1000Pa; the temperature input range of the combined measuring device is 25℃~300℃; the water contact angle range of different surfaces that can be measured by the combined measuring device is: 10°~170°.

[0067] In the above-mentioned combined measuring device, the temperature measuring device holes 41 of the heat conducting plate 4 are axially symmetrically distributed. The diameter of the heat conducting plate 4, the diameter of the temperature measuring device holes 41, the number of temperature measuring sensors, and the shear rate of the high-viscosity fluid are shown in Table 1. The size of the heat conducting plate 4, the size of the temperature measuring device holes 41 and the number and size of the temperature measuring sensors are matched to ensure that the deviation between the measured shear stress and the absence of the sensor is within 5%.

[0068]

[0069]

[0070] Table 1 Relationship between the diameter of the heat conducting plate, the diameter of the hole of the temperature measuring device, the number of temperature measuring sensors, and the shear rate of the high viscosity fluid. A combined measurement method based on a combined measurement device. The specific steps of the combined measurement method are as follows:

[0071] S1, preparing a heat conducting plate 4 having an upper surface with set wettability;

[0072] S2, embed the thermocouple 3 connected to the temperature recording system 31 into the corresponding temperature measuring device hole 41 of the heat conducting plate 4, and adjust the upper edge height of the thermocouple 3 according to the set requirements;

[0073] S3, assembling the heating film 5 with the temperature controller 51 and the heat conducting plate 4 embedded with the thermocouple 3 on the lifting platform of the mechanical lifting mechanism 24 in sequence;

[0074] S4, placing the high-viscosity fluid on the heat-conducting plate 4 and immersing all the thermocouples 3, controlling the mechanical lifting mechanism 24 to rise through the distance sensor control system 22 so that the high-viscosity fluid fits the bottom of the plate surface of the torque sensor 1, and adjusting the thickness of the high-viscosity fluid to 0.5mm-3mm through the linkage of the distance sensor 2, setting the shear rate of the torque sensor 1, and obtaining the torque M of the high-viscosity fluid through the torque sensor 1, the unit is N·m, the temperature controller 51 sets the heating temperature of the heating film 5, and the heating film 5 transmits constant heat to the high-viscosity fluid through the heat-conducting plate 4, the temperature recording system 31 records the initial ambient temperature of the experiment, and measures and records the real-time temperature T of the high-viscosity fluid at equal time intervals through the thermocouple 3 s , the unit is ℃;

[0075] S5. The torque M of the high-viscosity fluid obtained by the torque sensor 1 is used to calculate the shear stress τ of the high-viscosity fluid: τ = 2M / (πR 3 ), where the unit of shear stress τ is Pa, and R is the disk radius of the torque sensor, in m;

[0076] According to the room temperature during the experiment, the natural convection heat transfer coefficient of indoor air is obtained, and the unit is W·m -2 ·K -1 , the specific solution steps are:

[0077] S51. Obtain the Grashof number Gr of the indoor air: Gr = βgρ 2 Φ 3 ΔT / μ 2 , where β is the volume expansion coefficient of indoor air, unit is K -1 , ρ is the indoor air density under the test environment temperature conditions, g is the gravitational acceleration, the value is 9.8m / s 2 , Φ is the characteristic size (i.e., the diameter D of the heat conducting plate), the unit is m, ΔT is the temperature difference between the high viscosity fluid and the experimental environment temperature, the unit is K, μ is the viscosity of the indoor air, R is the radius of the torque sensor, the unit is m;

[0078] S52, obtain the Rayleigh number Ra of the indoor air: Ra=GrPr, Pr is the Prandtl number of the indoor air;

[0079] S53. Obtain the Nusselt number Nu of the indoor air: Nu = CRa n , C and n are empirical constants;

[0080] S54. Calculate the natural convection heat transfer coefficient h of indoor air: h = Nuλ / D, where λ is the thermal conductivity of indoor air in W·m -1 ·K -1 ;

[0081] S6, based on the natural convection heat transfer coefficient h of the indoor air and the temperature rise curve of the high viscosity fluid recorded by the temperature recording system 31, the average heat transfer coefficient of the high viscosity fluid is derived The specific solution steps are:

[0082] S61. Calculate the heat dissipation rate Q of the high viscosity fluid to the indoor air during the test a (W): Q a =hA a ΔT, where the heat dissipation rate Q a The unit is W, A a is the total area of ​​heat exchange between high viscosity fluid and indoor air, in m 2 ;

[0083] S62. Calculate the heat absorption rate Q when the temperature of the high viscosity fluid increases c : The heat absorption rate Q c The unit is W, c p is the specific heat capacity of the high viscosity fluid, the unit is J·kg -1 ·K -1 , m is the mass of the high viscosity fluid, the unit is kg, is the derivative of the experimental heating temperature;

[0084] S63. Calculate the total heat absorption rate Q of high viscosity fluid s :Q s =Q a +Q c , where the total heat absorption rate Q s The unit is W; S64, calculate the instantaneous heat transfer coefficient K at each moment i :K i =Q s / (A b ΔT1), where A b is the contact area between the high viscosity fluid and the heat source, in m 2 , ΔT1 is the temperature difference between the high viscosity fluid and the heat source, the unit is K;

[0085] S65. Obtain the average heat transfer coefficient of high viscosity fluid Where i is the parameter for the number of high viscosity fluid layers.

[0086] Embodiment 1

[0087] The specific steps of the combined determination method based on the device for combined determination of shear stress and heat transfer performance of high-viscosity fluid provided by the present invention are as follows:

[0088] (1) The upper surface of the heat conducting plate 4 made of aluminum is cleaned without any modification, and the water contact angle is less than 90°. The K-type thermocouple 3 is inserted into the ice-water mixture, and the thermocouple is calibrated to 0°C according to the displayed temperature; then, it is closely attached to the wiring groove 42 symmetrically distributed on the lower surface of the heat conducting plate 4, and inserted into the temperature measuring device hole 41 matching the thermocouple 3, and the upper edge of the thermocouple 3 is extended to a certain height from the upper surface of the heat conducting plate 4;

[0089] (2) The polyimide heating film 5 and the heat conducting plate 4 embedded with the K-type thermocouple 3 are assembled in sequence on the lifting platform of the mechanical lifting mechanism 24;

[0090] (3) Based on the height of the lifting platform sensed by the distance sensor 2, the distance sensor control system 22 is used to control the motor 21 to drive the mechanical lifting mechanism 24 to rise to a certain position, 0.46 ml of 3% carboxymethyl cellulose solution (3% CMC, viscosity range 0.14-7.58 Pa·s) is added to the heat conducting plate 4 as a high-viscosity fluid, and the distance sensor control system 22 is continued to control the mechanical lifting mechanism 24 to rise so that the high-viscosity fluid fits the bottom of the disk of the torque sensor 1, and the thickness of the high-viscosity fluid is adjusted to 1 mm through the linkage of the distance sensor 2;

[0091] (4) Set the torque sensor 1 to 0.01, 1, and 100 s respectively -1 The constant shear rate is set to start applying constant shear to the high-viscosity fluid, the shear time is set to 20 minutes, the temperature controller 51 is started, the heating temperature of the polyimide heating film 5 is set to a constant temperature of 40° C., a constant heat input is applied to the tested high-viscosity fluid, and the temperature recording system 31 is started to record the temperature;

[0092] (5) After the experiment, slowly remove the heat conducting plate 4, K-type thermocouple 3, and polyimide heating film 5 in sequence, and rinse the upper surface of the heat conducting plate 4 with deionized water;

[0093] (6) The torque M of the 3% carboxymethyl cellulose solution obtained by the torque sensor 1, and the shear stress of the 3% carboxymethyl cellulose solution;

[0094] According to the room temperature during the experiment, the natural convection heat transfer coefficient of indoor air h (W·m -2 ·K -1 ), the specific solution steps are:

[0095] Calculate the Grashof number Gr of indoor air: Gr = βgρ 2 Φ 3 ΔT / μ 2 , where β is the volume expansion coefficient of indoor air, unit is K -1, ρ is the indoor air density under the test environment temperature conditions, g is the gravitational acceleration, the value is 9.8m / s 2 , Φ is the characteristic size (i.e., the diameter D of the heat conducting plate), ΔT is the temperature difference between the 3% carboxymethyl cellulose solution and the experimental environment temperature, in K, μ is the viscosity of the indoor air (0.0000181 Pa·s), and R is the radius of the torque sensor (0.0125m);

[0096] Calculate the Rayleigh number Ra of the indoor air: Ra = GrPr, Pr is the Prandtl number of the indoor air;

[0097] Calculate the Nusselt number Nu of indoor air: Nu = CRa n , C and n are empirical constants;

[0098] The natural convection heat transfer coefficient of indoor air is obtained as follows: h = Nuλ / D, where λ is the thermal conductivity of indoor air (0.02632 W·m -1 ·K -1 );

[0099] (7) Based on the natural convection heat transfer coefficient h of the indoor air and the temperature rise curve of the high viscosity fluid recorded by the temperature recording system 31, the average heat transfer coefficient of the high viscosity fluid is derived. The instantaneous heat transfer coefficient of 3% carboxymethyl cellulose solution was derived by selecting a temperature point every 100 seconds from the recorded temperature. The specific solution steps are as follows:

[0100] Calculate the heat dissipation rate Q of 3% carboxymethyl cellulose solution to the indoor air during the test a (W): Q a =hA a ΔT, where the heat dissipation rate Q a The unit is W, A a The total heat exchange area between 3% carboxymethyl cellulose solution and indoor air is 0.000569m 2 ;

[0101] Calculate the heat absorption rate Q of 3% carboxymethyl cellulose solution when the temperature rises c : The heat absorption rate Q c The unit is W, c p The specific heat capacity of 3% carboxymethyl cellulose solution is 4200 J·kg -1 ·K -1 , m is the mass of 3% carboxymethyl cellulose solution, 0.000496kg, is the derivative of the experimental heating temperature;

[0102] Calculate the total heat absorption rate Q of 3% carboxymethyl cellulose solution s :Qs =Q a +Q c , where the total heat absorption rate Q s The unit is W;

[0103] Calculate the instantaneous heat transfer coefficient K of 3% carboxymethyl cellulose solution at each moment i :K i =Q s / (A b ΔT1), where A b The contact area between 3% carboxymethyl cellulose solution and heat source is 0.000490625m 2 , ΔT1 is the temperature difference between 3% carboxymethyl cellulose solution and heat source, unit is K;

[0104] Finally, the average heat transfer coefficient of 3% carboxymethyl cellulose solution was obtained Where i is the parameter for the number of high viscosity fluid layers.

[0105] Embodiment 2

[0106] The test steps of Example 2 are the same as those of Example 1, except that the high viscosity fluid tested this time is a 3% γ-polyglutamic acid solution (3% γ-PGA, viscosity range 0.07-1.04 Pa·s).

[0107] Comparative Example 1

[0108] The measurement steps of comparative example 1 are the same as those of embodiment 1, except that the upper surface of the heat conducting plate 4 is subjected to polydopamine interface construction by electrodeposition and then subjected to superhydrophobic modification (water contact angle greater than 150°).

[0109] Comparative Example 2

[0110] The measuring steps of comparative example 2 are the same as those of example 2, except that the upper surface of the heat conducting plate 4 is subjected to polydopamine interface construction by electrodeposition and then subjected to superhydrophobic modification (water contact angle greater than 150°).

[0111] The test data obtained by the combined determination method provided by the present invention in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Table 2 and Table 3, in which the test results of shear stress and average heat transfer coefficient of 3% carboxymethyl cellulose solution and 3% γ-polyglutamic acid solution are compared and analyzed. Figure 6 is the interfacial shear stress control factor Heat transfer enhancement factor Relationship curve, where Re is the Reynolds number, Re = D 2 Ωρ l / (2μ), Ω is the angular velocity of the disk of the torque sensor 1 rad / s, ρ l is the density of the high viscosity fluid.

[0112]

[0113] Table 2 Test results of shear stress and average heat transfer coefficient of 3% carboxymethyl cellulose solution (temperature 20℃)

[0114]

[0115] Table 3 Test results of shear stress and average heat transfer coefficient of 3% γ-polyglutamic acid solution (temperature 20°C)

[0116] By comparing Table 2 with Table 3, it is found that the Al surface is a hydrophilic surface and the polydopamine surface is a hydrophobic surface. The comparison between Example 1 and Comparative Example 1 shows that the combined determination device and combined determination method provided by the present invention can simultaneously determine the fluid shear stress and heat transfer coefficient. It is found that on the metal Al and polymer coating-polydopamine coating surface, under the same shear rate conditions, the shear stress of the fluid of the 3% carboxymethyl cellulose solution on the polydopamine coating surface is always lower than the result on the Al surface, and the heat transfer coefficient is more than 2 times higher than that on the Al surface. The comparison between Example 2 and Comparative Example 2 shows that under the same shear rate conditions, compared with the Al surface, the 3% γ-polyglutamic acid solution on the polydopamine coating surface also has a lower shear rate and higher heat transfer performance.

[0117] The high-viscosity fluid shear and heat transfer joint measurement system provided in the embodiments and comparative examples of the present invention measures the influence of shear stress regulation on the heat transfer effect of the high-viscosity fluid by selecting surfaces with different hydrophilicity and hydrophobicity; controls the temperature change by a temperature controller 51; uses a temperature recording system 31 to collect temperature data when the high-viscosity fluid is heated; and comprehensively considers the influence of room temperature on the heat transfer of the high-viscosity fluid; the measurement process is convenient and the results obtained are accurate.

[0118] The above-mentioned embodiments and comparative examples of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A heat conducting plate for jointly measuring shear stress and heat transfer performance of high viscosity fluids, characterized in that: The diameter D and thickness H of the cylindrical heat conducting plate (4) satisfy D / H=10-20. A plurality of temperature measuring device holes (41) distributed in an axisymmetric manner are arranged in the heat conducting plate (4). The temperature measuring device holes (41) arranged through the heat conducting plate (4) are used to install temperature measuring devices, and the sizes and quantities of the temperature measuring devices and the temperature measuring device holes (41) match each other.

2. The heat conducting plate for combined determination of shear stress and heat transfer performance of high viscosity fluid according to claim 1, characterized in that: The material of the heat conducting plate (4) includes aluminum, iron, copper, titanium, stainless steel, diamond-like carbon, titanium nitride and tungsten carbide; the diameter D of the heat conducting plate (4) is 10 mm to 100 mm, the thickness H is 1 mm to 5 mm, and the diameter d of the temperature measuring device hole (41) is 10 mm to 100 mm. T It is 0.2mm~1mm.

3. The heat conducting plate for combined determination of shear stress and heat transfer performance of high viscosity fluid according to claim 1, characterized in that: At least one wiring groove (42) is formed at the bottom of the heat conducting plate (4), and a signal line between a temperature measuring device installed in the temperature measuring device hole (41) and a temperature recording system (31) is arranged in the wiring groove (42).

4. The heat conducting plate for combined determination of shear stress and heat transfer performance of high viscosity fluid according to claim 3, characterized in that: The wiring groove (42) is arranged along the radial direction of the heat conducting plate (4) and penetrates the bottom of the heat conducting plate (4); the central axis of the temperature measuring device hole (41) is located at the vertex of the wiring groove (42); the wiring groove (42) is a semicircular groove, the diameter d of the semicircular groove is 1 mm to 5 mm, the length D is 10 mm to 100 mm, and D / d=10 to 20; the temperature measuring device hole (41) is arranged along the wiring groove (42), and the same wiring groove (42) is provided with N equal spacings of δ T The temperature measuring device hole (41) of the heat conducting plate (4) is δ, and the distance between the center of the temperature measuring device hole (41) closest to the outer edge of the heat conducting plate (4) and the outer edge of the heat conducting plate (4) is δ T-S , then N, δ T , δ T-S Satisfy D=2δ T-S +(N-1)×δ T , and the spacing is equal to δ T Satisfy δ T / D≥0.

25.

5. A combined measuring device, comprising a heat conducting plate (4) as claimed in any one of claims 1 to 4, and further comprising a torque sensor (1) and a torque sensor control system (11) connected to its circuit, a distance sensor (2) and a distance sensor control system (22) connected to its circuit, a mechanical lifting mechanism (24), a thermocouple (3) as a temperature measuring device and a temperature recording system (31) connected to its circuit, a heating film (5) and a temperature controller (51) connected to its circuit, and a bracket (6), wherein the distance sensor (2) is arranged below the lifting platform of the mechanical lifting mechanism (24) to provide real-time feedback on the height position of the lifting platform, and during the lifting of the mechanical lifting mechanism (24), the distance sensor (2) is arranged below the lifting platform of the mechanical lifting mechanism (24) to provide real-time feedback on the height position of the lifting platform. A heating film (5) and a heat-conducting plate (4) embedded with a thermocouple (3) are sequentially stacked on the platform. The thermocouple (3) is embedded in a temperature measuring device hole (41) and the upper edge of the thermocouple (3) protrudes from the upper edge of the heat-conducting plate (4), and the lower edge of the thermocouple (3) is located inside the heat-conducting plate (4). A torque sensor (1) suspended on a bracket (6) is arranged directly above the heat-conducting plate (4). The upper surface area of ​​the lifting platform, the surface area of ​​the heating film (5) and the area of ​​the heat-conducting plate (4) are of the same size. A high-viscosity fluid placed on the heat-conducting plate (4) can immerse the upper edge of the thermocouple (3) and the upper edge of the high-viscosity fluid can fit the bottom of the disk of the torque sensor (1) under the action of a mechanical lifting mechanism (24).

6. The combined assay device according to claim 5, characterized in that: The combined measuring device further comprises a motor (21), the motor (21) being connected to a distance sensor control system (22) through a line and being controlled by the distance sensor control system (22), and the motor (21) being connected to a mechanical lifting mechanism (24) through a transmission shaft (23) to input lifting power; the torque sensor control system (11) being used to set the shear rate and obtain the torque M of the high-viscosity fluid through the torque sensor (1); the linked distance sensor control system (22) and the distance sensor (2) controlling the height position of the lifting platform of the mechanical lifting mechanism (24) through the motor (21) to adjust the thickness of the high-viscosity fluid; the temperature controller (51) being used to set the heating temperature of the heating film (5) to deliver constant heat to the high-viscosity fluid through the heat conducting plate (4); and the temperature recording system (31) recording the initial ambient temperature of the experiment and measuring and recording the real-time temperature T of the high-viscosity fluid through the thermocouple (3). s ; The distance from the upper edge of the thermocouple (3) to the upper edge of the high-viscosity fluid is not less than 0.2 mm; The height of the thermocouples (3) on the heat-conducting plate (4) increases or decreases in the same diameter direction, and the height difference of the thermocouples (3) in the same diameter direction is not less than 0.2 mm; When the thickness of the high-viscosity fluid is h g , then the center positions of the N thermocouples (3) on the heat conducting plate (4) satisfy the arrangement spacing at the normal height of the heat conducting plate (4) (h g -0.4mm) / (N-1).

7. The combined assay device according to claim 5, characterized in that: The thermocouple (3) is a noble / cheap metal thermocouple of model S, R, B, N, K, E, J, T. Before using the thermocouple (3), it is necessary to perform a 0°C temperature calibration in an ice-water mixture. The heating film (5) comprises a polyimide film, a polyurea film, a polyimide-carbon fiber composite film, a zinc oxide film, and a carbon nanotube film. The heating temperature range of the heating film (5) is 25 to 300°C. The measurable torque range and corresponding error of the combined measuring device are: 0 to 100 N·m, ±0.5%, and the measurable shear rate range of the combined measuring device is: 0.01s -1 ~3600s -1 The shear stress range tested by the combined measuring device is 0.075Pa~1000Pa; the temperature input range of the combined measuring device is 25℃~300℃; the water contact angle range of different surfaces that can be measured by the combined measuring device is: 10°~170°.

8. A combined determination method, the combined determination method using the combined determination device according to any one of claims 5 to 7, characterized in that: The specific steps of the combined determination method are as follows: S1, preparing a heat-conducting plate (4) having an upper surface with set wettability; S2, embedding the thermocouple (3) connected to the temperature recording system (31) into the corresponding temperature measuring device hole (41) of the heat conducting plate (4), and adjusting the upper edge height of the thermocouple (3) according to the set requirements; S3, assembling the heating film (5) of the temperature controller (51) and the heat conducting plate (4) embedded with the thermocouple (3) on the lifting platform of the mechanical lifting mechanism (24) in sequence; S4, placing a high-viscosity fluid on a heat-conducting disk (4) and immersing all the thermocouples (3), controlling the mechanical lifting mechanism (24) to rise through the distance sensor control system (22) so that the high-viscosity fluid fits the bottom of the disk of the torque sensor (1), and adjusting the thickness of the high-viscosity fluid to 0.5 mm to 3 mm through the linkage of the distance sensor (2), setting the shear rate, and obtaining the torque M of the high-viscosity fluid through the torque sensor (1), the unit is N·m, the temperature controller (51) sets the heating temperature of the heating film (5), and the heating film (5) transmits constant heat to the high-viscosity fluid through the heat-conducting disk (4), the temperature recording system (31) records the initial ambient temperature of the experiment, and measures and records the real-time temperature T of the high-viscosity fluid at equal time intervals through the thermocouple (3). s , the unit is ℃; S5. The torque M of the high-viscosity fluid obtained by the torque sensor (1) is used to calculate the shear stress τ of the high-viscosity fluid: τ = 2M / (πR 3 ), where the unit of shear stress τ is Pa, and R is the disk radius of the torque sensor, in m; According to the room temperature during the experiment, the natural convection heat transfer coefficient of indoor air is obtained, and the unit is W·m -2 ·K -1 ; S6, based on the natural convection heat transfer coefficient h of the indoor air and the temperature rise curve of the high viscosity fluid recorded by the temperature recording system (31), deriving the average heat transfer coefficient of the high viscosity fluid The unit is W·m -2 ·K -1 .

9. The combined determination method according to claim 8, characterized in that: The specific steps for solving the natural convection heat transfer coefficient h of the indoor air in step S5 are: S51. Obtain the Grashof number Gr of the indoor air: Gr = βgρ 2 Φ 3 ΔT / μ 2 , where β is the volume expansion coefficient of indoor air, unit is K -1 , ρ is the indoor air density under the test environment temperature conditions, g is the gravitational acceleration, the value is 9.8m / s 2 , Φ is the characteristic dimension (the diameter D of the heat conducting plate), the unit is m, ΔT is the temperature difference between the high viscosity fluid and the experimental environment temperature, the unit is K, μ is the viscosity of the indoor air, R is the radius of the torque sensor, the unit is m; S52, obtain the Rayleigh number Ra of the indoor air: Ra=GrPr, Pr is the Prandtl number of the indoor air; S53. Obtain the Nusselt number Nu of the indoor air: Nu=CRa n , C and n are empirical constants; S54. Calculate the natural convection heat transfer coefficient h of indoor air: h = Nuλ / D, where λ is the thermal conductivity of indoor air, in W·m -1 ·K -1 .

10. The combined determination method according to claim 8, characterized in that: The average heat transfer coefficient of the high viscosity fluid in step S6 The specific solution steps are: S61. Calculate the heat dissipation rate Q of the high viscosity fluid to the indoor air during the test a (W): Q a =hA a ΔT, where the heat dissipation rate Q a The unit is W, A a is the total area of ​​heat exchange between high viscosity fluid and indoor air, in m 2 ; S62. Calculate the heat absorption rate Q when the temperature of the high viscosity fluid increases c : The heat absorption rate Q c The unit is W, c p is the specific heat capacity of the high viscosity fluid, the unit is J·kg -1 ·K -1 , m is the mass of the high viscosity fluid, the unit is kg, is the derivative of the experimental heating temperature; S63. Calculate the total heat absorption rate Q of high viscosity fluid s :Q s =Q a +Q c , where the total heat absorption rate Q s The unit is W; S64. Obtain the instantaneous heat transfer coefficient K at each moment i :K i =Q s / (A b ΔT1), where A b is the contact area between the high viscosity fluid and the heat source, in m 2 , ΔT1 is the temperature difference between the high viscosity fluid and the heat source, the unit is K; S65. Obtain the average heat transfer coefficient of high viscosity fluid Where i is the parameter for the number of high viscosity fluid layers.

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