A test device and method for measuring the surface heat dissipation coefficient of a concrete thin-walled structure

Abstract

The application discloses a kind of test device and method for measuring the surface heat dissipation coefficient of concrete thin-walled structure, it is related to concrete surface heat dissipation coefficient measurement field, method includes: by obtaining the temperature of concrete test block in specified depth, the humidity of multiple measuring points of concrete test block, ambient temperature, ambient humidity and environmental wind speed;The humidity of multiple measuring points of the concrete test block is averaged, and the humidity of concrete test block is obtained;Determine whether the surface of concrete test block has water and determine whether the temperature of specified depth in the concrete test block is greater than the ambient temperature, and then select different concrete heat dissipation coefficient formula to calculate the heat dissipation coefficient of the concrete test block.The application can calculate the heat dissipation coefficient of concrete according to multiple variables, so as to improve the accuracy of the measurement of concrete heat dissipation coefficient.

Description

Technical Field

[0001] This invention relates to the field of measuring the heat dissipation coefficient of concrete surfaces, and in particular to a test apparatus and method for measuring the heat dissipation coefficient of thin-walled concrete structures. Background Technology

[0002] In practical engineering, the surface heat dissipation coefficient calculated by empirical formulas cannot accurately simulate the actual conditions of concrete surfaces. Furthermore, empirical formulas only use a single variable (wind speed), which deviates significantly from actual values. Additionally, in numerical simulations, values ​​are often derived empirically without insulation; for example, when concrete is in contact with air, the heat dissipation coefficient β = 40–80 kJ / (m²). 2 (·h·℃); When concrete comes into contact with water, the heat dissipation coefficient β=8000~16000kJ / (m²) 2 The heat dissipation coefficient (·h·℃) is a variable that, due to human subjectivity, can have a wide range of values ​​and may not match the actual temperature field. Specialized instruments can also be used to measure the heat dissipation coefficient of concrete surfaces, but these instruments are expensive and have limited applications. Summary of the Invention

[0003] The purpose of this invention is to provide a test device and method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, which can improve the accuracy of measuring the heat dissipation coefficient of the concrete surface.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A device for measuring the surface heat dissipation coefficient of a thin-walled concrete structure includes: a temperature and humidity simulation chamber, a wind speed detection unit, a temperature detection unit, a humidity detection unit, a data transmission unit, and a monitoring and analysis terminal.

[0006] The temperature and humidity simulation chamber is used to simulate the ambient temperature and humidity of the concrete test block. The wind speed detection unit, the temperature detection unit, and the humidity detection unit are placed in the temperature and humidity simulation chamber.

[0007] The wind speed detection unit is used to detect the wind speed in the environment inside the box;

[0008] The temperature detection unit is used to detect the temperature of multiple temperature measurement points on the concrete test block and the ambient temperature.

[0009] The humidity detection unit is used to detect the humidity and ambient humidity at multiple humidity measurement points on the concrete test block.

[0010] The wind speed detection unit, the temperature detection unit, and the humidity detection unit are all connected to the data transmission unit; the data transmission unit is used to transmit the wind speed of the environment inside the chamber, the temperature of multiple temperature measurement points of the concrete test block, the ambient temperature, the humidity of multiple humidity measurement points of the concrete test block, and the ambient humidity to the monitoring and analysis terminal.

[0011] The monitoring and analysis terminal is used to calculate the heat dissipation coefficient of the concrete specimen based on the wind speed inside the chamber, the temperature of multiple temperature measurement points of the concrete specimen, the ambient temperature, the humidity of multiple humidity measurement points of the concrete specimen, and the ambient humidity.

[0012] A method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, the method being applied to the aforementioned device for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, the method comprising:

[0013] The temperature at a set depth in the concrete specimen, the humidity at multiple measurement points of the concrete specimen, the ambient temperature, the ambient humidity, and the ambient wind speed were obtained.

[0014] The humidity of the concrete test block is obtained by averaging the humidity at multiple measurement points.

[0015] Determine if there is water on the surface of the concrete test block;

[0016] If the surface of the concrete test block is dry, then according to Calculate the heat dissipation coefficient of the concrete specimen; where β represents the heat dissipation coefficient of the concrete specimen; v a For ambient wind speed; Indicates the humidity of the concrete test block;

[0017] If there is water on the surface of the concrete test block, then determine whether the temperature at a set depth in the concrete test block is greater than the ambient temperature.

[0018] If the temperature at a set depth in the concrete test block is greater than the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete specimen; where Δt is the difference between the temperature at a set depth in the concrete specimen and the ambient temperature; and U is the difference between the humidity of the concrete specimen and the ambient humidity.

[0019] If the temperature at a set depth in the concrete test block is less than or equal to the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete test block.

[0020] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0021] The present invention provides an experimental apparatus and method for measuring the surface heat dissipation coefficient of thin-walled concrete structures. This involves acquiring the temperature at a set depth within a concrete specimen, the humidity at multiple measurement points on the concrete specimen, the ambient temperature, ambient humidity, and ambient wind speed; averaging the humidity at the multiple measurement points to obtain the humidity of the concrete specimen; determining whether there is water on the surface of the concrete specimen and whether the temperature at the set depth within the concrete specimen is greater than the ambient temperature; and then applying the formula... or The heat dissipation coefficient of the concrete specimen is calculated. This invention can calculate the heat dissipation coefficient of concrete based on multiple variables, thereby improving the accuracy of concrete heat dissipation coefficient measurement. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 Structural diagram of the device for measuring the surface heat dissipation coefficient of thin-walled concrete structures provided by the present invention;

[0024] Figure 2 This is a schematic diagram showing the position setting of the anemometer in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the wind speed detection unit arrangement in an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram showing the arrangement of each monitoring unit in an embodiment of the present invention;

[0027] Figure 5 This is a top view of a concrete test block in an embodiment of the present invention;

[0028] Figure 6 As described in the embodiments of the present invention Figure 5 AA-side elevation view;

[0029] Figure 7 As described in the embodiments of the present invention Figure 5 BB elevation view;

[0030] Figure 8 This is a schematic diagram of the automatic water spraying unit in an embodiment of the present invention;

[0031] Figure 9 Flowchart of the method for measuring the heat dissipation coefficient of a thin-walled concrete structure provided by the present invention;

[0032] Figure 10 This is a flowchart illustrating the finite element method for reproducing the heat dissipation coefficient of a concrete surface in an embodiment of the present invention.

[0033] Figure 11 This is a schematic diagram of the average temperature measurement points in an embodiment of the present invention;

[0034] Figure 12 This is a comparison chart of the temperature calculation curve and the measured curve of feature point 1 based on the inversion parameters in this embodiment of the invention;

[0035] Figure 13 This is a comparison chart of the temperature calculation curve and the measured curve of feature point 2 based on the inversion parameters in this embodiment of the invention;

[0036] Figure 14 This is a comparison chart of the temperature calculation curve and the measured curve of feature point 3 based on the inversion parameters in this embodiment of the invention;

[0037] Figure 15 This is a comparison chart of the temperature calculation curve and the measured curve of feature point 4 based on the inversion parameters in this embodiment of the invention;

[0038] Figure 16 This is a comparison chart of the temperature calculation curve and the measured curve of feature point 5 based on the inversion parameters in this embodiment of the invention;

[0039] Figure 17 This is a schematic diagram of the third type of boundary conditions in an embodiment of the present invention;

[0040] Figure 18 This is a flowchart of the method for analytically fitting the surface heat dissipation coefficient in an embodiment of the present invention;

[0041] Figure 19 Taking the example of a concrete surface without water and a wind speed of 0 m / s in this embodiment of the invention, the curve of the surface heat dissipation coefficient process is analyzed and fitted.

[0042] Figure 20 This is a graph showing the relationship between ambient wind speed and the heat dissipation coefficient of concrete surface when the concrete surface is dry, as described in this embodiment of the invention.

[0043] Figure 21 This is a graph showing the relationship between the heat dissipation coefficient of the concrete surface and different ambient humidity levels when the concrete surface is dry, as described in this embodiment of the invention.

[0044] Figure 22 This is a graph showing the relationship between the heat dissipation coefficient of the concrete surface and different ambient humidity levels when the concrete surface is dry, as described in this embodiment of the invention.

[0045] Figure 23 This is a graph showing the relationship between the heat dissipation coefficient of the concrete surface and different ambient temperatures when water is sprayed on the concrete surface in an embodiment of the present invention.

[0046] Figure 24 This is a graph showing the relationship between the heat dissipation coefficient of the concrete surface and different ambient wind speeds when water is sprayed on the concrete surface in an embodiment of the present invention.

[0047] Figure 25 This is a graph showing the relationship between the heat dissipation coefficient of the concrete surface and different ambient humidity levels when water is sprayed on the concrete surface in an embodiment of the present invention.

[0048] Figure 26 This is a flowchart illustrating the fitting process for the heat dissipation coefficient of the concrete surface in an embodiment of the present invention. Detailed Implementation

[0049] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The purpose of this invention is to provide a test apparatus and method for measuring the heat dissipation coefficient of thin-walled concrete structures, thereby improving the accuracy of concrete surface heat dissipation coefficient measurement. This invention improves upon existing empirical formulas for the heat dissipation coefficient of concrete surfaces, making them more explicit and easier to operate.

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1

[0053] This embodiment introduces the experimental instruments and their arrangement, as well as the principles for placing temperature sensors within concrete. It describes the experimental method for simulating environmental variables (ambient temperature, humidity, and wind speed). The relationship between the surface heat dissipation coefficient and individual variables is derived through finite element inversion. Simultaneously, the relationship between the surface heat dissipation coefficient and individual variables is fitted using analytical expressions for third-type boundary conditions, the purpose of which is to compare and correct with the finite element inversion method. Finally, the experimental data obtained from both methods are analyzed and organized to derive expressions relating the surface heat dissipation coefficient to multiple environmental variables.

[0054] The temperature and humidity of the concrete surface and the temperature at different depths inside the concrete are obtained; the temperature, humidity and wind speed of the surrounding environment of the concrete are obtained; by changing the ambient temperature and humidity, ambient wind speed and the humidity of the concrete surface, a multi-factor coupled heat dissipation coefficient expression is established; the variables are combined to form multiple sets of test conditions, and finally the relationship between a single variable and surface heat dissipation is obtained through experiments, and finally the multi-variable relationship is linked together to form the relationship between the surface heat dissipation coefficient and multiple variables.

[0055] This invention solves the problem of inaccurate measurement of the heat dissipation coefficient of thin-walled concrete surfaces, and resolves the fuzzy and inaccurate heat dissipation coefficient of concrete under the combined influence of different ambient temperatures and humidity, different surface humidity, and different ambient wind speeds. It provides a guarantee for temperature control and crack prevention of thin-walled concrete, and has guiding significance for crack prevention during the construction of thin-walled concrete such as spillway lining, spillway, and earth-rock dam panels.

[0056] like Figure 1 As shown, the present invention provides an experimental device for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, comprising: a temperature and humidity simulation chamber, a wind speed detection unit, a temperature detection unit, a humidity detection unit, a data transmission unit, and a monitoring and analysis terminal.

[0057] The temperature and humidity simulation chamber is used to simulate the ambient temperature and humidity of the concrete test block. The wind speed detection unit, the temperature detection unit, and the humidity detection unit are placed in the temperature and humidity simulation chamber.

[0058] The wind speed detection unit is used to detect the wind speed in the environment inside the box.

[0059] Furthermore, the wind speed detection unit includes an anemometer, a blower, a suction fan, a vent pipe, a first control valve, an air tank, a second control valve, and an exhaust pipe.

[0060] The blower is located on one side inside the temperature and humidity simulation chamber, and the suction fan is located on the other side inside the chamber. The concrete specimen is placed between the blower and the suction fan. The anemometer is located on the concrete specimen near the suction fan. The anemometer is connected to the data transmission unit. The anemometer is used to measure the wind speed inside the chamber. In practical applications, the anemometer is either a rotor anemometer or an ultrasonic anemometer.

[0061] The anemometer is placed on the other side of the blower nozzle, and its impeller anemometer or ultrasonic anemometer must be positioned directly opposite the blower nozzle. For example, two impeller anemometers can be placed at one end of the concrete specimen block with a distance of 0.2m between them, or the ultrasonic anemometer can be placed 0.05m away from one end of the concrete specimen block. Figure 2 As shown.

[0062] The vent pipe, the first control valve, the air storage tank, the second control valve, and the exhaust pipe are connected in sequence; the vent pipe is connected to the suction fan; the vent pipe, the first control valve, the air storage tank, the second control valve, and the exhaust pipe are located outside the temperature and humidity simulation chamber, as shown below. Figure 3 As shown.

[0063] In practical applications, the temperature and humidity of the environment are controlled by temperature control. However, the temperature and humidity simulation chamber is sealed. In order to simulate wind speed in different environments and prevent the wind from swirling in the sealed temperature and humidity simulation chamber, the wind speed simulation design is as follows: an adjustable high-power blower is used. When the blower blows air, the suction fan starts at the same time. The suction fan draws the blown air into the air tank and compresses it. The gas is then discharged when the air pressure stabilizes.

[0064] Hair dryers and exhaust fans have the same structure and operating principle as regular electric fans. Hair dryers mainly use a motor to drive a fan to blow air, while exhaust fans use a motor to drive a turbine to draw air into an air tank.

[0065] The temperature detection unit is used to detect the temperature of multiple temperature measurement points on the concrete test block and the ambient temperature.

[0066] Furthermore, the temperature detection unit includes a first T-type thermocouple temperature sensor, a second T-type thermocouple temperature sensor, and a third T-type thermocouple temperature sensor; all of the T-type thermocouple temperature sensors are connected to the data transmission unit.

[0067] The first T-type thermocouple temperature sensor is installed on the upper surface of the concrete specimen; the second T-type thermocouple temperature sensor is installed inside the concrete specimen; the first T-type thermocouple temperature sensor and the second T-type thermocouple temperature sensor are used to collect the temperature of multiple temperature measurement points of the concrete specimen.

[0068] The third type T thermocouple temperature sensor is installed inside the temperature and humidity simulation chamber to collect the ambient temperature.

[0069] In practical applications, the general arrangement of the relevant instruments is as follows: Figure 4 As shown, approximately eight T-type thermocouple thermometers (T-type thermocouple temperature sensors) are arranged on the concrete surface, and 16 thermometers are embedded inside the concrete. Two impeller anemometers or one ultrasonic anemometer are arranged on one side of the concrete. Three hygrometers collect the humidity of the concrete surface, and one hygrometer collects the humidity of the ambient air. The thermometers are T-type thermocouple thermometers, which have high measurement accuracy, are unaffected by intermediate media, have a wide measurement range, simple structure, and are easy to use. Furthermore, Figure 4 The wind speed acquisition device is the first data transmission unit, the temperature acquisition device is the second data transmission unit, and the humidity acquisition device is the third data transmission unit.

[0070] A total of 24 T-type thermocouple thermometers were installed on and inside the concrete surface. Four thermometers were installed in the middle of the concrete surface, and two thermometers were installed on each side of the concrete, for a total of eight thermometers on the surface. The positions of the thermometers are as follows: Figure 5 As shown (black dots represent thermometer measuring points), the purpose is to accurately measure the temperature of the concrete surface. Measuring the temperature of the concrete surface requires not only measuring the temperature at the center but also the temperature of the surrounding surfaces to ensure accurate measurement.

[0071] The spacing between measuring points on the concrete surface is as follows Figure 6 As shown, measuring points are fixed at different depths in the concrete. Cables extend from both sides of the specimen and connect to the recorder (data transmission unit). The thermometers are spaced 2cm, 4cm, 8cm, and 10cm apart. This is to measure the temperature and temperature change from the center point of the thin-walled concrete to the concrete surface. The thermometers are arranged more closely at the surface to accurately measure the temperature gradient near the concrete surface. The measuring point arrangement is as follows... Figure 6 and Figure 7 As shown, the principle of its arrangement is from dense to sparse, which not only allows for the measurement of the temperature gradient from the surface of thin-walled concrete (concrete specimen) to the center of the concrete interior, but also allows for the precise measurement of the temperature gradient near the concrete surface, thus improving the accuracy of the test results.

[0072] The humidity detection unit is used to detect the humidity and ambient humidity at multiple humidity measurement points on the concrete test block.

[0073] Furthermore, the humidity detection unit includes a first humidity meter and a second humidity meter; both the first humidity meter and the second humidity meter are connected to the data transmission unit.

[0074] The first humidity meter is installed on the upper surface of the concrete test block to collect humidity data at multiple humidity measurement points on the concrete test block.

[0075] The second humidity meter is installed inside the temperature and humidity simulation chamber and is used to collect the ambient humidity.

[0076] The wind speed detection unit, temperature detection unit, and humidity detection unit are all connected to the data transmission unit. The data transmission unit is used to transmit the wind speed inside the chamber, the temperature at multiple temperature measurement points of the concrete specimen, the ambient temperature, the humidity at multiple humidity measurement points of the concrete specimen, and the ambient humidity to the monitoring and analysis terminal. In practical applications, the data transmission unit includes a first data transmission unit, a second data transmission unit, and a third data transmission unit.

[0077] The monitoring and analysis terminal is used to calculate the heat dissipation coefficient of the concrete specimen based on the wind speed inside the chamber, the temperature of multiple temperature measurement points of the concrete specimen, the ambient temperature, the humidity of multiple humidity measurement points of the concrete specimen, and the ambient humidity.

[0078] Furthermore, the concrete thin-walled structure surface heat dissipation coefficient measuring device of the present invention also includes: an automatic water spraying unit; the automatic water spraying unit is connected to the monitoring and analysis terminal.

[0079] The monitoring and analysis terminal is also used to compare the humidity of the concrete test block with a set threshold; the automatic water spraying unit is used to spray water onto the concrete test block when the humidity of the concrete test block is less than the set threshold.

[0080] The automatic sprinkler unit includes a storage tank, a circulation pump, and multiple nozzles; the storage tank, the circulation pump, and the multiple nozzles are connected by water pipes; the circulation pump is connected to the monitoring and analysis terminal, such as... Figure 8 As shown, water on the concrete surface is sprayed onto the concrete surface using an automatic water spraying unit. Water at a certain temperature can be sprayed at regular intervals and in measured quantities through a circulating pump and a water storage tank.

[0081] The device for measuring the surface heat dissipation coefficient of thin-walled concrete structures of the present invention further includes: an insulation board; the insulation board is disposed on the side and bottom of the concrete specimen. A 5cm thick styrene insulation board (i.e., ...) is arranged around the concrete perimeter and on the bottom surface. Figure 6 and Figure 7 The insulation board in the middle is made of polystyrene board, and the joints of the insulation board are bonded with aluminum foil insulation cotton.

[0082] Example 2

[0083] This invention also provides a method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, such as... Figure 9 As shown, the method is applied to the test apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure in Example 1. The method includes:

[0084] Step 901: Obtain the temperature at a set depth in the concrete test block, the humidity at multiple measurement points of the concrete test block, the ambient temperature, the ambient humidity, and the ambient wind speed.

[0085] Step 902: Take the average value of the humidity at multiple measurement points of the concrete test block to obtain the humidity of the concrete test block.

[0086] Step 903: Determine if there is water on the surface of the concrete test block.

[0087] Step 904: If the surface of the concrete test block is dry, then according to 856. Calculate the heat dissipation coefficient of the concrete specimen. Where β represents the heat dissipation coefficient of the concrete specimen; v a For ambient wind speed; This indicates the humidity level of the concrete test block.

[0088] Step 905: If there is water on the surface of the concrete test block, determine whether the temperature at a set depth in the concrete test block is greater than the ambient temperature.

[0089] Step 906: If the temperature at a set depth in the concrete test block is greater than the ambient temperature, then according to... Calculate the heat dissipation coefficient of the concrete specimen. Where Δt is the temperature difference between the concrete specimen at a set depth and the ambient temperature; U is the humidity difference between the concrete specimen and the ambient humidity.

[0090] Step 907: If the temperature at a set depth in the concrete test block is less than or equal to the ambient temperature, then according to... Calculate the heat dissipation coefficient of the concrete test block.

[0091] Example 3

[0092] This invention also provides a test method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, such as... Figure 26 As shown, the specific steps are as follows:

[0093] This method mainly involves changing the concrete surface environment, such as changing different wind speeds, humidity levels, and ambient temperature and humidity. By changing these environmental variables, data analysis is conducted to derive the relationship between the surface heat dissipation coefficient and a single variable. Finally, through polynomial fitting, an expression is derived to derive the relationship between the surface heat dissipation coefficient and multiple variables.

[0094] Step 1: Set up the test apparatus for measuring the heat dissipation coefficient of the surface of a thin-walled concrete structure as described in Example 1.

[0095] Step 2: Use a temperature and humidity simulation chamber to simulate the ambient temperature and humidity of the concrete test block, so that the interior of the concrete test block reaches the set temperature.

[0096] Step 3: Change the ambient temperature, ambient humidity, and ambient wind speed, and collect test data for concrete specimens under different working conditions. The test data includes the internal temperature, surface temperature, surface humidity, and real-time wind speed of the concrete specimens; the working conditions include concrete with water on the surface and concrete without water on the surface.

[0097] Step 4: Based on the experimental data, use the finite element inversion method to determine the first expression for the heat dissipation coefficient of the concrete surface under different working conditions and a single variable. The single variable is ambient temperature, ambient humidity, or ambient wind speed.

[0098] Step 5: Based on the experimental data, use the third type of boundary condition analytical method to determine the second expression of the heat dissipation coefficient of the concrete surface and the single variable under different working conditions.

[0099] Through analysis and research, the test conditions were divided into two categories: with and without surface water, as shown in Tables 1 and 2, and expressions were established for each. The heat dissipation coefficient of the concrete surface can be inverted using the finite element inversion method, as shown in Tables 1 and 2. Figure 10 As shown. At the same time, the surface heat dissipation coefficient is fitted based on the relationship between the temperature gradient and the surface heat dissipation coefficient by using the analytical expression of the third type of boundary condition, such as equations (1-5).

[0100] Table 1 Test conditions for a dry concrete surface

[0101]

[0102]

[0103] Table 2 Test conditions for concrete surfaces with water

[0104]

[0105]

[0106] (1) Finite element inversion method

[0107] In this embodiment, only the surface heat dissipation coefficient needs to be inverted during the parameter inversion process; other thermal parameters do not need to be inverted. The finite element simulation method is used for the inversion, and the steps are as follows: Figure 10 As shown, a lower limit for the heat dissipation coefficient needs to be set. The surface heat dissipation coefficient is gradually increased based on the error between the measured value and the calculated value at the measurement point. When the error is minimized, the inverted surface heat dissipation coefficient is the closest to the true surface heat dissipation coefficient. Since the inversion parameter is a single parameter, this method has advantages such as high inversion accuracy and fast inversion efficiency.

[0108] During the inversion process, the center point of the concrete surface (0cm) and locations at distances of 2cm, 6cm, 14cm, and 24cm from the center point are taken as inversion feature points (intervals of 2cm, 4cm, 8cm, and 10cm). In the actual calculation process, the temperature values ​​of different measuring points at the same spatial depth are averaged into a single temperature value, such as... Figure 11As shown, the average temperature values ​​of the surface points A to H are averaged to form the temperature of the surface center point, which is taken as the temperature of feature point 1. The average temperature of the other four measuring points at the same depth is taken as the temperature of feature points 2-5. The purpose is to make the process of inverting the concrete surface coefficient convenient, fast and accurate.

[0109] Taking operating condition GK1 as an example, the comparison between the calculated and measured curves of the characteristic point temperature based on the inversion parameters is shown in the figure below. Figures 12-16 As shown.

[0110] (2) Analytical Fitting Method

[0111] The heat dissipation coefficient of concrete surface is the most important coefficient in the heat balance condition. Unlike thermal conductivity, the heat dissipation coefficient of concrete surface is an indicator of the strength of convective heat transfer between fluid and solid surface.

[0112] When concrete comes into contact with air, the heat flow passing through the concrete surface is:

[0113]

[0114] The third type of boundary condition assumes that the heat flow passing through the concrete surface is related to the concrete surface temperature T and the air temperature T. a The difference is directly proportional to the ambient temperature. That is:

[0115]

[0116] In formula (2): β is the surface heat transfer coefficient, kJ / (m²). 2 ·h·℃).

[0117] The third type of boundary condition describes the heat transfer conditions when a solid comes into contact with a fluid (such as air). Air is generally in a turbulent state, but a viscous (laminar) boundary layer exists near the solid surface. Within the viscous layer, the temperature is linearly distributed; in the turbulent region, due to intense fluid mixing, the temperature is nearly uniform. According to the third type of boundary condition, such as... Figure 17 As shown, in the viscous flow boundary layer near the solid surface, there is no convective mixing, and heat transfer mainly relies on conduction. The temperature distribution is approximately linear. When the temperature drops sharply from T to T... a The temperature is uniform within the turbulent region. The thickness of the viscous boundary layer is δ, and the temperature gradient is approximately equal to -(TT). a Therefore, the heat is: ) / δ

[0118]

[0119] This heat is equal to the heat transferred from the interior of the solid through its surface. Right now

[0120]

[0121] In formula (4): λ c Let be the thermal conductivity of the fluid. Comparing equations (2) and (3), it can be seen that:

[0122] β=λ c / δ (5)

[0123] Fluid thermal conductivity λ c The boundary layer thickness δ depends on the properties of the fluid. It depends on the surface roughness of the solid, the viscosity of the fluid, and the flow velocity. The surface heat transfer coefficient β is independent of the material properties of the solid itself, but is determined by the surface roughness of the solid, the thermal conductivity and viscosity of the fluid, the flow velocity, and the flow direction.

[0124] Based on field tests, this study investigates the variation patterns of temperature and temperature gradient near the concrete surface over distance and time. The heat dissipation coefficient of the concrete surface is fitted using measured temperature data. Then, by analyzing the relationship between the surface heat dissipation coefficient and temperature gradient under the third type of boundary conditions, the heat dissipation coefficient of the concrete surface is calculated using the midpoint temperature and temperature gradient within a range of 0.03m to 0.09m from the concrete surface. In this embodiment, the surface heat dissipation coefficient is retrieved by selecting the midpoint temperature and temperature gradient at a distance of 0.06m from the concrete surface. Figure 18 As shown, the specific steps are as follows:

[0125] 1) Select the center point at a distance of 0.06m as the reference point.

[0126] 2) Real-time recording of temperature at 0.06m, concrete surface temperature, and ambient temperature.

[0127] 3) Calculate the temperature gradient from 0.06m to the concrete surface.

[0128] 4) Calculate the surface heat dissipation coefficient of concrete according to the analytical expression of the third type of boundary conditions.

[0129] Based on equation (2), the temperature at the midpoint of the concrete surface (0.06m) and the temperature gradient are selected to fit the heat dissipation coefficient of the concrete surface. This is because the midpoint near the concrete surface is easily affected by the environment. Figure 19 As shown in the figure, the surface heat dissipation coefficient process diagram fitted by analytical equation (2) is used as an example with no water on the concrete surface and a wind speed of 0 m / s. According to the fitted process line, the surface heat dissipation is basically 1050 kJ / (m²). 2 (approximately ·h·℃).

[0130] Finally, the relationship between the surface heat dissipation coefficient and a single environmental variable was established using finite element or analytical methods. This was based on heat dissipation theory from textbooks and relationships derived through curve fitting from experiments. The relationship between the concrete surface heat dissipation coefficient and ambient wind speed or temperature and humidity was obtained. For example, when the concrete surface is dry, the surface heat dissipation coefficient is related to the 0.8 power of the wind speed; when the concrete surface is wet, the surface heat dissipation coefficient has a non-linear relationship with the wind speed. Then, multiple environmental variables were coupled together to establish an expression under multi-factor coupling conditions.

[0131] (3) Results analysis and organization

[0132] Through data analysis, a relationship expression between the heat dissipation coefficient of concrete surface and a single variable was derived. When the concrete surface is dry, the heat dissipation coefficient is mainly related to the ambient wind speed and ambient humidity. When the concrete surface is wet, considering the effect of evaporation, the heat dissipation coefficient is mainly related to: the difference between surface humidity and ambient humidity, and the difference between water surface temperature and ambient temperature.

[0133] 1) When the surface is dry, the relationship between the heat dissipation coefficient of the concrete surface and different wind speeds is shown in Table 3.

[0134] Table 3. Relationship between surface heat dissipation coefficient and different wind speeds under specific environmental conditions.

[0135]

[0136]

[0137] In summary, with constant concrete temperature and ambient temperature and humidity, higher ambient wind speeds result in better heat dissipation from the concrete surface and a higher surface heat dissipation coefficient. To verify the relationship between wind speed and the surface heat dissipation coefficient, experimentally derived measured data were fitted with empirical formulas for wind speed and analytical formulas for third-type boundary conditions, resulting in the following: Figure 20 The effect shown.

[0138] When the surface is dry, the expression for the heat dissipation coefficient of the concrete surface versus the ambient wind speed, obtained using the finite element inversion method, is as follows:

[0139] The expression for the heat dissipation coefficient of the concrete surface versus the ambient wind speed, obtained using the analytical method of the third type of boundary conditions, is as follows:

[0140] From the fitting results, by comparing the three sets of data, the surface heat dissipation coefficient fitted by the finite element method has a linear relationship with the wind speed to the power of 0.85, while the surface heat dissipation coefficient fitted by the analytical method has a linear relationship with the wind speed to the power of 0.6.

[0141] 2) When the surface is dry, the relationship between the heat dissipation coefficient of the concrete surface and different ambient humidity is shown in Table 4.

[0142] Table 4. Relationship between surface heat dissipation coefficient and different ambient humidity under specific conditions.

[0143]

[0144]

[0145] In summary, when the ambient temperature is low and the ambient humidity increases, excess water vapor will condense on the concrete surface and in the air, inhibiting heat dissipation from the concrete. By fitting the experimentally derived measured data with the analytical formula for the third type of boundary conditions, the following conclusions are drawn: Figure 21 As shown in the figure, when the ambient temperature is low, the heat dissipation coefficient of the concrete surface decreases as the ambient humidity increases.

[0146] When the surface is dry, the expression for the heat dissipation coefficient of the concrete surface in relation to ambient humidity, obtained using the finite element inversion method, is as follows:

[0147] The expression for the heat dissipation coefficient of concrete surface versus ambient humidity, obtained using the analytical method of the third type of boundary conditions, is as follows:

[0148] 3) When the surface is dry, the relationship between the surface heat dissipation coefficient and different ambient humidity is shown in Table 5.

[0149] Table 5. Relationship between surface heat dissipation coefficient and different ambient temperatures under specific environmental conditions.

[0150]

[0151] In summary, combining the inversion results and the study of the third type of boundary condition mechanism, when the concrete surface is dry, the ambient humidity remains constant, and the wind speed is 0 m / s, changing the ambient temperature has little effect on the heat dissipation coefficient of the concrete surface, which is generally between 1000 and 1400 kJ / (m²). 2 Between ·d·℃), such as Figure 22 As shown.

[0152] When the surface is dry, the expression for the heat dissipation coefficient of the concrete surface as a function of ambient temperature, obtained using the finite element inversion method, is β = -14.111T. C +1529.4.

[0153] The expression for the heat dissipation coefficient of the concrete surface in relation to ambient temperature, obtained using the analytical method of the third type of boundary conditions, is β = -24.4T. C +1477.8.

[0154] 4) When water is sprayed on the surface, the relationship between the heat dissipation coefficient of the concrete surface and different ambient temperatures is shown in Table 6.

[0155] Table 6. Relationship between surface heat dissipation coefficient and different ambient temperatures under specific environmental conditions (spraying water).

[0156]

[0157] In summary, when water is sprayed on a concrete surface, with the concrete and ambient humidity remaining constant, changing the ambient temperature leads to faster evaporation and greater heat loss when the ambient temperature is higher than the temperature of the water film on the concrete surface. Higher ambient temperatures result in faster evaporation and a higher heat dissipation coefficient on the concrete surface. When the ambient temperature is lower than the temperature of the water film on the concrete surface, cold air in the environment forms a cold water film on the surface, inhibiting evaporation. Lower ambient temperatures result in a lower surface heat dissipation coefficient. Based on measured data, expressions for the heating and cooling stages can be fitted, such as... Figure 23 As shown.

[0158] When there is water on the surface, the expression for the heat dissipation coefficient of the concrete surface versus the ambient temperature, obtained using the finite element inversion method, is as follows:

[0159] The expression for the heat dissipation coefficient of the concrete surface versus ambient temperature, obtained using the analytical method of the third type of boundary conditions, is as follows:

[0160] 5) When water is sprayed on the surface, the relationship between the heat dissipation coefficient of the concrete surface and different ambient wind speeds is shown in Table 7.

[0161] Table 7. Relationship between surface heat dissipation coefficient and different ambient wind speeds under specific environmental conditions (spraying water).

[0162]

[0163] In summary, when there is water on the concrete surface, as the ambient wind speed increases, the evaporation heat dissipation of the concrete increases, and the heat dissipation coefficient of the concrete surface increases. When the ambient wind speed reaches a certain limit, a cold water film will form on the concrete surface, inhibiting evaporation. Figure 24 As shown in the figure. The experimental data shows that when the ambient wind speed is between 0 and 1.79 m / s, the evaporation is faster as the wind speed increases. When the ambient wind speed is greater than 1.79 m / s, the surface heat dissipation coefficient decreases as the wind speed increases due to the influence of the cold water film on the concrete surface.

[0164] When there is water on the surface, the expression for the heat dissipation coefficient of the concrete surface versus the ambient temperature, obtained using the finite element inversion method, is as follows:

[0165] The expression for the heat dissipation coefficient of the concrete surface versus ambient temperature, obtained using the analytical method of the third type of boundary conditions, is as follows:

[0166] 6) The relationship between the heat dissipation coefficient of the concrete surface and different ambient humidity levels when water is sprayed on the surface is shown in Table 8.

[0167] Table 8. Relationship between surface heat dissipation coefficient and different ambient humidity levels under specific environmental conditions (spraying water).

[0168]

[0169] In summary, with the concrete temperature and ambient temperature remaining constant, spraying water onto the concrete surface results in a decreasing humidity difference between the concrete surface and the ambient environment as ambient humidity increases. Figure 25 As shown in the analysis, when water is sprayed on the concrete surface, the lower the ambient humidity, the better the heat dissipation and the greater the surface heat dissipation coefficient.

[0170] When there is water on the surface, the expression for the heat dissipation coefficient of the concrete surface in relation to the ambient temperature, obtained by the finite element inversion method, is β = 3229.2lnU - 4508.3.

[0171] The expression for the heat dissipation coefficient of the concrete surface in relation to the ambient temperature, obtained using the analytical method of the third type of boundary conditions, is β = 2731.2lnU - 889.43.

[0172] Therefore, when the concrete surface is dry, the surface heat dissipation coefficient is related to the ambient wind speed to the power of 0.85 and to the ambient humidity to the power of 1. When the concrete surface is wet, the surface heat dissipation coefficient is related to the ambient wind speed to the power of 0.5 and to the humidity difference U (humidity of concrete surface %RH - ambient humidity %RH) logarithmically.

[0173] Step 6: Organize and fit the first expression and the second expression to obtain the expression for the heat dissipation coefficient of the concrete surface and multiple variables under different working conditions; the multiple variables include ambient temperature, ambient humidity and ambient wind speed.

[0174] 1. When the concrete surface is dry, based on the relationship between the surface heat dissipation coefficient and the dependent variable, the relationship between the concrete surface heat dissipation coefficient and a single environmental variable is summarized.

[0175] ① The surface heat dissipation coefficient is related to the wind speed to the power of 0.8:

[0176] ② The surface heat dissipation coefficient has a linear relationship with humidity:

[0177] ③ The surface heat dissipation coefficient has a linear relationship with the environment: β=-24.4T C +1477.8, According to experimental results and theoretical research, when the concrete surface is dry, the ambient temperature has little effect on surface heat dissipation.

[0178] ④ The expression for multi-factor coupling under drying conditions is obtained by fitting a polynomial:

[0179]

[0180] Finally, through multiple sets of experimental data, the polynomial coefficients a, b, and c were determined: a = 630, b = 3.6, and c = 1.34.

[0181]

[0182] 2. When there is water on the concrete surface, based on the relationship between the surface heat dissipation coefficient and the dependent variable, the relationship between the concrete surface heat dissipation coefficient and a single environmental variable is summarized.

[0183] ① The surface heat dissipation coefficient has a non-linear relationship with the wind speed, and its expression is:

[0184]

[0185] ② The surface heat dissipation coefficient has a logarithmic relationship with the humidity difference, and its expression is:

[0186] β = 2731.2lnU - 889.43

[0187] ③ The surface heat dissipation coefficient has a non-linear relationship with the ambient temperature, and its expression is:

[0188]

[0189] ④ By fitting the multivariate time-dependent expression for multi-factor coupling under drying conditions:

[0190] ⑤ When the ambient temperature is greater than or equal to the concrete temperature:

[0191] ⑥ When the ambient temperature is lower than the concrete temperature:

[0192] ⑦ Finally, through multiple sets of experimental data, the polynomial coefficients a, b, c, d, and e were determined, showing that when the ambient temperature is greater than or equal to the concrete temperature:

[0193] When the ambient temperature is lower than the concrete temperature:

[0194] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0195] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A test apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, characterized in that, include: Temperature and humidity simulation chamber, wind speed detection unit, temperature detection unit, humidity detection unit, data transmission unit, and monitoring and analysis terminal; The temperature and humidity simulation chamber is used to simulate the ambient temperature and humidity of the concrete test block. The wind speed detection unit, the temperature detection unit, and the humidity detection unit are placed in the temperature and humidity simulation chamber. The wind speed detection unit is used to detect the wind speed in the environment inside the box; The temperature detection unit is used to detect the temperature of multiple temperature measurement points on the concrete test block and the ambient temperature. The humidity detection unit is used to detect the humidity and ambient humidity at multiple humidity measurement points on the concrete test block. The wind speed detection unit, the temperature detection unit, and the humidity detection unit are all connected to the data transmission unit; the data transmission unit is used to transmit the wind speed of the environment inside the chamber, the temperature of multiple temperature measurement points of the concrete test block, the ambient temperature, the humidity of multiple humidity measurement points of the concrete test block, and the ambient humidity to the monitoring and analysis terminal. The monitoring and analysis terminal is used to calculate the heat dissipation coefficient of the concrete test block based on the wind speed in the chamber, the temperature at multiple temperature measurement points of the concrete test block, the ambient temperature, the humidity at multiple humidity measurement points of the concrete test block, and the ambient humidity. The heat dissipation coefficient of the concrete specimen is calculated based on the wind speed inside the chamber, the temperature at multiple temperature measurement points on the concrete specimen, the ambient temperature, the humidity at multiple humidity measurement points on the concrete specimen, and the ambient humidity. Specifically, this includes: The humidity of the concrete test block is obtained by averaging the humidity at multiple measurement points. Determine if there is water on the surface of the concrete test block; If the surface of the concrete test block is dry, then according to Calculate the heat dissipation coefficient of the concrete test block; wherein, Indicates the heat dissipation coefficient of the concrete test block; For ambient wind speed; Indicates the humidity of the concrete test block; If there is water on the surface of the concrete test block, then determine whether the temperature at a set depth in the concrete test block is greater than the ambient temperature. If the temperature at a set depth in the concrete test block is greater than the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete test block; wherein, The temperature difference between the specified depth and the ambient temperature in the concrete test block; The difference between the humidity of the concrete test block and the ambient humidity; If the temperature at a set depth in the concrete test block is less than or equal to the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete test block.

2. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 1, characterized in that, The wind speed detection unit includes an anemometer, a blower, a suction fan, a ventilation duct, a first control valve, an air tank, a second control valve, and an exhaust pipe; The blower is located on one side inside the temperature and humidity simulation chamber, the suction fan is located on the other side inside the temperature and humidity simulation chamber, and the concrete test block is placed between the blower and the suction fan; the anemometer is located on the concrete test block near the suction fan; the anemometer is connected to the data transmission unit; the anemometer is used to measure the wind speed in the environment inside the chamber. The vent pipe, the first control valve, the gas storage tank, the second control valve, and the exhaust pipe are connected in sequence; the vent pipe is connected to the suction fan; the vent pipe, the first control valve, the gas storage tank, the second control valve, and the exhaust pipe are located outside the temperature and humidity simulation chamber.

3. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 2, characterized in that, The anemometer is either a rotor anemometer or an ultrasonic anemometer.

4. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 1, characterized in that, The temperature detection unit includes a first T-type thermocouple temperature sensor, a second T-type thermocouple temperature sensor, and a third T-type thermocouple temperature sensor; all of the T-type thermocouple temperature sensors are connected to the data transmission unit. The first T-type thermocouple temperature sensor is arranged on the upper surface of the concrete test block; The second T-type thermocouple temperature sensor is installed inside the concrete specimen; the first T-type thermocouple temperature sensor and the second T-type thermocouple temperature sensor are used to collect the temperature of multiple temperature measurement points of the concrete specimen. The third type T thermocouple temperature sensor is installed inside the temperature and humidity simulation chamber to collect the ambient temperature.

5. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 1, characterized in that, The humidity detection unit includes a first humidity meter and a second humidity meter; both the first humidity meter and the second humidity meter are connected to the data transmission unit. The first humidity meter is installed on the upper surface of the concrete test block to collect humidity data at multiple humidity measurement points on the concrete test block. The second humidity meter is installed inside the temperature and humidity simulation chamber and is used to collect the ambient humidity.

6. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 1, characterized in that, Also includes: An automatic sprinkler unit; the automatic sprinkler unit is connected to the monitoring and analysis terminal; The monitoring and analysis terminal is also used to compare the humidity of the concrete test block with a set threshold; the automatic water spraying unit is used to spray water onto the concrete test block when the humidity of the concrete test block is less than the set threshold.

7. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 6, characterized in that, The automatic sprinkler unit includes a storage tank, a circulation pump, and multiple nozzles; The storage tank, the circulation pump, and the multiple nozzles are connected by water pipes; the circulation pump is connected to the monitoring and analysis terminal.

8. The experimental apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure according to claim 1, characterized in that, Also includes: Insulation board; the insulation board is disposed on the side and bottom of the concrete test block.

9. A method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, characterized in that, The method is applied to the test apparatus for measuring the heat dissipation coefficient of a thin-walled concrete structure as described in any one of claims 1-8, and the method includes: The temperature at a set depth in the concrete specimen, the humidity at multiple measurement points of the concrete specimen, the ambient temperature, the ambient humidity, and the ambient wind speed were obtained. The humidity of the concrete test block is obtained by averaging the humidity at multiple measurement points. Determine if there is water on the surface of the concrete test block; If the surface of the concrete test block is dry, then according to Calculate the heat dissipation coefficient of the concrete test block; wherein, Indicates the heat dissipation coefficient of the concrete test block; For ambient wind speed; Indicates the humidity of the concrete test block; If there is water on the surface of the concrete test block, then determine whether the temperature at a set depth in the concrete test block is greater than the ambient temperature. If the temperature at a set depth in the concrete test block is greater than the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete test block; wherein, The temperature difference between the specified depth and the ambient temperature in the concrete test block; The difference between the humidity of the concrete test block and the ambient humidity; If the temperature at a set depth in the concrete test block is less than or equal to the ambient temperature, then according to Calculate the heat dissipation coefficient of the concrete test block.

10. A test method for measuring the heat dissipation coefficient of a thin-walled concrete structure surface, characterized in that, include: Arrange the test apparatus for measuring the heat dissipation coefficient of the surface of a thin-walled concrete structure as described in any one of claims 1-8; A temperature and humidity simulation chamber was used to simulate the ambient temperature and humidity of the concrete test block, so that the interior of the concrete test block reached the set temperature. The test data of concrete specimens were collected under different working conditions by changing the ambient temperature, ambient humidity, and ambient wind speed. The test data included the internal temperature, surface temperature, surface humidity, and real-time wind speed of the concrete specimens. The working conditions included concrete with water on the surface and concrete without water on the surface. Based on the experimental data, the first expression for the heat dissipation coefficient of concrete surface and a single variable under different working conditions was determined using the finite element inversion method. The single variable is ambient temperature, ambient humidity, or ambient wind speed; Based on the experimental data, the second expression for the heat dissipation coefficient of concrete surface and a single variable under different working conditions was determined using the method of analytical expression of the third type of boundary conditions. The first and second expressions are rearranged and fitted to obtain expressions for the heat dissipation coefficient of concrete surface and multiple variables under different working conditions; the multiple variables include ambient temperature, ambient humidity and ambient wind speed.

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