Crucible Temperature Distribution Calculation via Plasma Radiation Modeling
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Solution Overview
Problem
Current methods for manufacturing vitreous silica crucibles lack accuracy in calculating temperature distribution during the arc discharge process, as they do not account for plasma emission and heat radiation, leading to inaccuracies in melting speed and bubble ratio control.
Innovation Solution
A method using the finite element method to calculate temperature distribution, incorporating heat convection and radiation models, with boundary conditions adjusted based on measured data to accurately model plasma heating and radiation effects, allowing for precise control of arc discharge parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional simulation methods (finite element method or finite difference method) are used to calculate temperature distribution, then computational capability is provided, but accuracy of temperature distribution calculation is insufficient because plasma emission and heat radiation are not taken into account
Solution Approach 1:
The patent applies parameter changes by modifying the simulation model to include plasma emission parameters and heat radiation parameters. The simulation calculates temperature distribution while varying parameters such as plasma power, radiation coefficients, and boundary conditions to accurately represent the actual manufacturing process physics.
Solution Approach 2:
The patent introduces an intermediary measurement system that captures actual temperature distribution during manufacturing. This measured data serves as a mediator to validate and calibrate the simulation model, enabling accurate boundary condition setting for plasma emission and heat radiation without requiring direct measurement of these complex physical phenomena.
2Manufacturing precision
If arc discharge parameters are adjusted based on experience and intuition, then manufacturing process can be operated, but manufacturing precision of crucible is insufficient
Solution Approach 1:
The patent creates a virtual copy of the manufacturing process through simulation. The simulation model replicates the arc discharge heating process, allowing parameter optimization to be performed in the virtual environment. Once optimized parameters are identified through simulation, they can be directly applied to actual manufacturing, eliminating time-consuming trial and error adjustments.
Solution Approach 2:
The patent performs preliminary optimization of arc discharge parameters using simulation before actual manufacturing. By calculating the temperature distribution and evaluating melting state in advance, the optimal parameter settings are determined beforehand, allowing direct application to production without requiring time-consuming experimental adjustments during manufacturing.
3Measurement precision
If boundary conditions are not corrected with measured data, then simulation can be performed, but accuracy of temperature distribution and melting speed calculation is insufficient
Solution Approach 1:
The patent implements feedback by measuring actual temperature distribution during manufacturing and using this data to correct and update the simulation boundary conditions. The measured temperature values feed back into the simulation model, continuously improving the accuracy of plasma emission and heat radiation parameter settings without requiring manual intervention for each adjustment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate calculation of temperature distribution and melting speed, reducing bubble content and improving crucible quality by aligning calculated and measured values, thus optimizing manufacturing conditions without the need for experimental trial and error.
Implementation Method 1
heat convection due to a gas flow
Implementation Method 2
radiation of heat plasma and radiation heat of the arc discharge itself
Implementation Method 3
heat plasma generated by supplying discharge current to arc electrodes
Implementation Method 4
melting the raw material polycrystalline silicon by a heater provided around the crucible
Data Source
AI summary
Provided is a method of calculating a temperature distribution with higher accuracy than a conventional method, which calculates a temperature distribution of an inner surface of a silica powder molded body during manufacturing based on boundary conditions corrected in accordance with the actually measured temperature in consideration of plasma radiation by arc discharge and heat radiation of arc discharge.According to a method of calculating a temperature distribution of a crucible during manufacturing, includes a temperature calculation process in which a temperature calculator calculates temperature distribution in an inner surface of a silica powder molded body through a numerical calculation method which mesh-divides an object to be calculated, by calculating heat flux from heat plasma modeled by a gas flow and radiation of heat plasma radiated from arc electrodes, wherein the temperature distribution is calculated by adjusting gas flow and radiation conditions in a way that the calculated temperature distribution and the actually measured temperature distribution of an inner surface of a silica powder molded body becomes similar, and reading, from a correspondence table, gas flow and radiation conditions corresponding each step of a control sequence for producing a crucible.