A mold interface gap heat transfer analysis method and system based on a multi-thermal resistance layer model

Abstract

The present application relates to a kind of crystallizer interface gap heat transfer analysis method and system based on multiple thermal resistance layer model, method includes the following steps: step 1: build crystallizer interface gap multilayer thermal resistance structure model;Step 2: calculate interface gap total heat transfer coefficient;Step 3: calculate the equivalent additional gap depth of vibration mark;Step 4: calculate radiation heat transfer coefficient;Step 5: based on MEMS thermal sensor online detection is carried out heat self-consistent verification.The present application builds interface gap heat transfer model including multiple thermal resistance layer, comprehensively considers the influence of gas gap, covering powder, vibration mark and other factors on heat transfer, using multilayer thermal resistance coupling analysis method, can accurately quantify the real heat exchange boundary condition between crystallizer and casting blank, provides accurate theoretical basis for crystallizer taper optimization, covering powder selection and process parameter adjustment.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical engineering technology and relates to a method and system for analyzing heat transfer in the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model. Background Technology

[0002] In continuous casting, molten steel is forced to cool after being injected into the crystallizer from the tundish, and solidifies in a short time to form a primary billet shell. The interfacial gap of the crystallizer refers to the area between the solidified billet shell surface and the crystallizer wall, which contains multiple thermal resistance layers such as billet shell vibration marks, liquid slag film, solid slag film and air gaps, making the heat transfer mechanism extremely complex. In the existing technology, simplified empirical formulas or average heat flux density are usually used to describe the heat transfer behavior of the crystallizer, lacking a systematic consideration of the composition of each thermal resistance layer in the interfacial gap and their mutual influence. The main technical defects are as follows: (1) It is impossible to accurately describe the influence of air gap formation on heat transfer; (2) It does not consider the contribution of vibration mark structure to the equivalent thermal resistance; (3) It lacks coupling analysis of the distribution of protective slag morphology and heat transfer behavior; (4) It is difficult to combine online heat flux detection for self-consistent verification of heat transfer. These problems lead to a large deviation between the theoretical analysis of the heat transfer behavior of the crystallizer and the actual working conditions, affecting the quality control of the cast billet and process optimization. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method and system for analyzing heat transfer in the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model.

[0004] To achieve the above objectives, the present invention provides the following technical solution: On one hand, this invention provides a method for analyzing heat transfer at the interface gaps of a crystallizer based on a multi-thermal-resistance layer model, comprising the following steps: Step 1: Construct a multi-layer thermal resistance structure model of the crystallizer interface gap; Step 2: Calculate the overall heat transfer coefficient of the interfacial gap; Step 3: Calculate the equivalent additional gap depth of the oscillation mark; Step 4: Calculate the radiative heat transfer coefficient; Step 5: Perform heat transfer self-consistency verification based on online detection using MEMS thermal sensors.

[0005] Furthermore, the multi-layer thermal resistance structure model described in step 1 includes an equivalent layer of vibration marks, a liquid slag film layer, a solid slag film layer, an air gap layer, and a contact thermal resistance layer with the crystallizer wall.

[0006] Furthermore, the overall heat transfer coefficient of the interfacial gap mentioned in step 2 Calculate using the following formula:

[0007] in, To protect the contact thermal resistance between the slag and the crystallizer wall; , , , These are the air gap thickness, solid slag film thickness, liquid slag film thickness, and vibration mark equivalent additional gap depth, respectively. , , , The equivalent thermal conductivity is calculated for air, solid slag, liquid slag, and vibration marks, respectively. is the radiative heat transfer coefficient.

[0008] Furthermore, the equivalent additional gap depth of the oscillation mark in step 3 is calculated using the following formula:

[0009] in, The depth of the oscillation mark. The width of the oscillation mark. The distance between the vibration marks. The thermal conductivity of the protective slag film in the gap, The thermal conductivity of the oscillation mark.

[0010] Furthermore, the depth of the oscillation mark is calculated using the following formula:

[0011] in Indicates the thickness of the liquid slag layer. Indicates the negative slip time of crystallizer vibration; Calculate using the following formula:

[0012] in Indicates the skewness of the crystallizer vibration waveform. Indicates the crystallizer vibration frequency. Indicates pulling speed.

[0013] Furthermore, the oscillation mark spacing is calculated using the following formula: .

[0014] Furthermore, the radiative heat transfer coefficient in step 4 is calculated using the following formula:

[0015] in, To protect the refractive index of the slag, This is the Stefen-Boltzmann constant. To protect the absorption coefficient of the slag, and The surface emissivity of the protective slag and the steel billet are respectively. The solidification temperature of the billet shell. To protect the solidification temperature of the slag, For the thickness of the liquid slag film, The average depth of the volumetric vibration mark.

[0016] Furthermore, the heat transfer self-consistency condition in step 5 is:

[0017] in, This is the temperature reading of the copper plate. This is the measured value of heat flux density. The temperature of the cooling water for the crystallizer. The thickness from the detection point to the cold surface of the copper plate. For the thermal conductivity of copper plate, The effective heat transfer coefficient of the cooling water.

[0018] Furthermore, the MEMS thermal sensors are arranged in a matrix on the copper plate of the crystallizer to simultaneously detect local temperature and local heat flux density.

[0019] On the other hand, the present invention provides a crystallizer interface gap heat transfer analysis system based on a multi-thermal-resistance layer model, applicable to the crystallizer interface gap heat transfer analysis method based on the multi-thermal-resistance layer model as described above. The system includes: The multi-layer thermal resistance structure model includes an air gap thermal resistance layer, a solid slag film thermal resistance layer, a liquid slag film thermal resistance layer, a vibration mark equivalent thermal resistance layer, and a contact thermal resistance layer. Each thermal resistance layer is set sequentially according to the heat transfer direction from the crystallizer wall to the solidified billet surface. The overall heat transfer coefficient calculation unit calculates the overall heat transfer coefficient of the interfacial gaps based on the series relationship of the thermal resistance of multiple layers. The equivalent depth calculation unit for oscillation marks calculates the equivalent additional gap depth of oscillation marks based on a weighted average of the geometric features of the oscillation marks and the thickness of the protective slag film. The radiation heat transfer coefficient calculation unit calculates the radiation heat transfer contribution for semi-transparent glassy slag films or liquid slag films. The heat transfer self-consistency verification unit verifies the model calculation results based on temperature and heat flux density data detected online by MEMS thermal sensors.

[0020] The beneficial effects of this invention are as follows: 1) For the first time, a multi-layer thermal resistance structure model including air gap, solid slag film, liquid slag film, oscillation mark equivalent layer and contact thermal resistance was constructed, which comprehensively considered various heat transfer influencing factors of the crystallizer interface gap and significantly improved the accuracy of heat transfer analysis. 2) A quantitative calculation method for the equivalent additional gap depth of oscillation marks was proposed, which transforms the geometric characteristics of oscillation marks into equivalent thermal resistance parameters, thus solving the problem of quantitative description of the influence of oscillation marks on heat transfer. 3) A calculation model for the radiation heat transfer coefficient was established, taking into account the contribution of the semi-transparent characteristics of the protective slag to radiation heat transfer, making the heat transfer analysis in the high-temperature region more accurate. 4) A heat transfer self-consistent verification method based on online detection of MEMS thermal sensors is introduced, which can calibrate the model calculation results through measured data to ensure the reliability of the analysis results; 5) It provides accurate theoretical basis for optimizing crystallizer process parameters, selecting protective slag, and designing copper plate taper, which helps to improve billet quality and prevent sticking and leakage accidents.

[0021] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 A schematic diagram of the multilayer thermal resistance structure at the interface gap of the crystallizer; Figure 2 This is the equivalent circuit diagram of the interface gap thermal resistance layer; Figure 3 A simplified structural diagram of the oscillation marks on the cast billet; Figure 4 This is a schematic diagram of the heat transfer self-consistency verification principle based on MEMS thermal sensors. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0025] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0026] Example 1: like Figure 1-4 As shown, this invention provides a method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model, characterized by comprising the following steps: Step 1: Construct a multi-layer thermal resistance structure model of the crystallizer interface gap. The model includes an equivalent layer of vibration marks, a liquid slag film layer, a solid slag film layer, an air gap layer, and a contact thermal resistance layer of the crystallizer wall arranged sequentially along the heat transfer direction.

[0027] Step 2: Calculate the overall heat transfer coefficient of the interfacial gap according to the following formula. :

[0028] in, To protect the contact thermal resistance between the slag and the crystallizer wall; , , , These are the air gap thickness, solid slag film thickness, liquid slag film thickness, and vibration mark equivalent additional gap depth, respectively. , , , The equivalent thermal conductivity is calculated for air, solid slag, liquid slag, and vibration marks, respectively. is the radiative heat transfer coefficient.

[0029] Step 3: Calculate the equivalent additional gap depth of the oscillation mark according to the following formula. :

[0030] in, The depth of the oscillation mark. The width of the oscillation mark. The distance between the vibration marks. The thermal conductivity of the protective slag film in the gap, The thermal conductivity of the oscillation mark.

[0031] Step 4: Calculate the radiative heat transfer coefficient using the following formula. :

[0032] in, To protect the refractive index of the slag, This is the Stefen-Boltzmann constant. To protect the absorption coefficient of the slag, and The surface emissivity of the protective slag and the steel billet are respectively. The solidification temperature of the billet shell. To protect the solidification temperature of the slag, The average depth of the volumetric vibration mark.

[0033] Step 5: Obtain the local temperature and heat flux density of the copper plate in the crystallizer through online detection using MEMS thermal sensors. Verify the model calculation results based on the heat transfer self-consistency condition, which is:

[0034] in, This is the temperature reading of the copper plate. This is the measured value of heat flux density. The temperature of the cooling water for the crystallizer. The thickness from the detection point to the cold surface of the copper plate. For the thermal conductivity of copper plate, The effective heat transfer coefficient of the cooling water.

[0035] Example 2: This embodiment uses a slab continuous casting machine in a steel plant as the application object. The slab size is 1500mm × 230mm, the casting speed is 1.0m / min, and the solidification temperature of the protective slag is 1050℃. The heat transfer analysis of the interfacial gap in the crystallizer is performed according to the method in Example 1: First, temperature and heat flux density data of each detection point on the copper plate of the crystallizer are acquired by a MEMS thermal sensor array. The sensors are arranged in 3 rows and 16 columns, and the insertion depth of the detection point is 22 mm. Secondly, the vibration mark depth and spacing are calculated based on the on-site vibration process parameters. The amplitude is 9mm, the vibration frequency is 120rpm, and the negative slip time is calculated according to formula (4). Based on formula (3), the vibration mark depth is 0.45mm, the vibration mark width is 4.5mm, and the vibration mark spacing is calculated as 8.33mm according to formula (7). Then, based on the physical properties of the protective slag (density 2500 kg / m³, thermal conductivity 1.5 W / (m·℃), refractive index 1.5, absorption coefficient 250 m), - ¹), Substitute into the formulas in steps 2 to 4 to calculate the thickness and heat transfer coefficient of each thermal resistance layer, and obtain the thickness range of the liquid slag film at different locations below the meniscus as 0.2 to 0.4 mm, and the thickness range of the solid slag film as 0.5 to 1.5 mm. Finally, the self-consistency condition from step 5 was used for verification. The relative deviation between the calculated and detected values ​​was less than 1%, indicating that the model is accurate and reliable.

[0036] The air gap distribution characteristics obtained by this method can be used to guide the optimization of the inverted taper of narrow-face copper plates, and the liquid slag film thickness distribution can be used to evaluate the lubrication performance of protective slag, providing a quantitative basis for process parameter adjustment.

[0037] Example 3: This embodiment provides a crystallizer interface gap heat transfer analysis system based on a multi-thermal-resistance layer model, applicable to the crystallizer interface gap heat transfer analysis method based on a multi-thermal-resistance layer model described in Embodiment 1. The system includes: The multi-layer thermal resistance structure model includes an air gap thermal resistance layer, a solid slag film thermal resistance layer, a liquid slag film thermal resistance layer, a vibration mark equivalent thermal resistance layer, and a contact thermal resistance layer. Each thermal resistance layer is set sequentially according to the heat transfer direction from the crystallizer wall to the solidified billet surface. The overall heat transfer coefficient calculation unit calculates the overall heat transfer coefficient of the interfacial gaps based on the series relationship of the thermal resistance of multiple layers. The equivalent depth calculation unit for oscillation marks calculates the equivalent additional gap depth of oscillation marks based on a weighted average of the geometric features of the oscillation marks and the thickness of the protective slag film. The radiation heat transfer coefficient calculation unit calculates the radiation heat transfer contribution for semi-transparent glassy slag films or liquid slag films. The heat transfer self-consistency verification unit verifies the model calculation results based on temperature and heat flux density data detected online by MEMS thermal sensors.

[0038] Example 4: An electronic device, comprising a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the method described in Embodiment 1 when executing the computer program.

[0039] Example 5: A computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0040] Example 6: A computer program product includes a computer program that, when executed by a processor, implements the method described in Example 1.

[0041] In the above embodiments, the reference to "this embodiment" in the specification indicates that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple appearances of "this embodiment" do not necessarily refer to the same embodiment.

[0042] In the above embodiments, although the invention has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory structures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed. The embodiments of the invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims.

[0043] As will be understood by those skilled in the art, the computer-readable storage medium described in this embodiment allows for the implementation of all or part of the steps in the above method embodiments by computer program-related hardware. The aforementioned computer program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0044] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver, and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication between them. The memory is used to store computer programs, the communication interface is used to perform communication, and the processor and the transceiver are used to run the computer programs, so that the electronic terminal performs the steps of the above method.

[0045] In this embodiment, the memory may include random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage device.

[0046] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0047] This invention can be used in a wide range of general-purpose or special-purpose computing system environments or configurations. Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments including any of the above systems or devices, etc.

[0048] This invention can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This invention can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model, characterized in that: Includes the following steps: Step 1: Construct a multi-layer thermal resistance structure model of the crystallizer interface gap; Step 2: Calculate the overall heat transfer coefficient of the interfacial gap; Step 3: Calculate the equivalent additional gap depth of the oscillation mark; Step 4: Calculate the radiative heat transfer coefficient; Step 5: Perform heat transfer self-consistency verification based on online detection using MEMS thermal sensors.

2. The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: The multi-layer thermal resistance structure model described in step 1 includes an equivalent layer of vibration marks, a liquid slag film layer, a solid slag film layer, an air gap layer, and a contact thermal resistance layer with the crystallizer wall.

3. The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: The overall heat transfer coefficient of the interfacial gap mentioned in step 2 Calculate using the following formula: in, To protect the contact thermal resistance between the slag and the crystallizer wall; , , , These are the air gap thickness, solid slag film thickness, liquid slag film thickness, and vibration mark equivalent additional gap depth, respectively. , , , The equivalent thermal conductivity is calculated for air, solid slag, liquid slag, and vibration marks, respectively. denoted as the radiative heat transfer coefficient.

4. The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: In step 3, the equivalent additional gap depth of the oscillation mark is calculated using the following formula: in, The depth of the oscillation mark. The width of the oscillation mark. The distance between the vibration marks. The thermal conductivity of the protective slag film in the gap, The thermal conductivity of the oscillation mark.

5. The method for analyzing heat transfer across the interfacial gap of a crystallizer based on a multi-thermal-resistance layer model according to claim 4, characterized in that: The depth of the oscillation mark is calculated using the following formula: in Indicates the thickness of the liquid slag layer. Indicates the negative slip time of crystallizer vibration; Calculate using the following formula: in Indicates the skewness of the crystallizer vibration waveform. Indicates the crystallizer vibration frequency. Indicates pulling speed.

6. The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model according to claim 4, characterized in that: The oscillation mark spacing is calculated using the following formula: 。 7. The method for analyzing heat transfer across the interfacial gap of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: In step 4, the radiative heat transfer coefficient is calculated using the following formula: in, To protect the refractive index of the slag, This is the Stefen-Boltzmann constant. To protect the absorption coefficient of the slag, and The surface emissivity of the protective slag and the steel billet are respectively. The solidification temperature of the billet shell. To protect the solidification temperature of the slag, For the thickness of the liquid slag film, The average depth of the volumetric vibration mark.

8. The method for analyzing heat transfer across the interfacial gap of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: The heat transfer self-consistency condition in step 5 is: in, This is the temperature reading of the copper plate. This is the measured value of heat flux density. The temperature of the cooling water in the crystallizer. The thickness from the detection point to the cold surface of the copper plate. For the thermal conductivity of copper plate, The effective heat transfer coefficient of the cooling water.

9. The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model according to claim 1, characterized in that: The MEMS thermal sensors are arranged in a matrix on the copper plate of the crystallizer to simultaneously detect local temperature and local heat flux density.

10. A crystallizer interface gap heat transfer analysis system based on a multi-thermal-resistance layer model, characterized in that: The method for analyzing heat transfer across the interfacial gaps of a crystallizer based on a multi-thermal-resistance layer model, applicable to any one of claims 1-9, comprises: The multi-layer thermal resistance structure model includes an air gap thermal resistance layer, a solid slag film thermal resistance layer, a liquid slag film thermal resistance layer, a vibration mark equivalent thermal resistance layer, and a contact thermal resistance layer. Each thermal resistance layer is set sequentially according to the heat transfer direction from the crystallizer wall to the solidified billet surface. The overall heat transfer coefficient calculation unit calculates the overall heat transfer coefficient of the interfacial gaps based on the series relationship of the thermal resistance of multiple layers. The equivalent depth calculation unit for oscillation marks calculates the equivalent additional gap depth of oscillation marks based on a weighted average of the geometric features of the oscillation marks and the thickness of the protective slag film. The radiation heat transfer coefficient calculation unit calculates the radiation heat transfer contribution for semi-transparent glassy slag films or liquid slag films. The heat transfer self-consistency verification unit verifies the model calculation results based on temperature and heat flux density data detected online by MEMS thermal sensors.

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