A directional solidification phase change interface dynamic regulation method, device and medium

Abstract

The application discloses a directional solidification phase change interface dynamic regulation method and device and medium, relates to the directional solidification regulation technical field, and comprises the following steps: calculating the current heat flow density by using the working medium flow of each heat pipe section and the temperature difference between the working medium import and export, giving the current heat flow direction, synchronously positioning the phase change interface position, and obtaining the actual form of the phase change interface; comparing the actual form of the phase change interface with the set form of the phase change interface to obtain the interface leading distance and the interface lagging distance; judging the target heat flow direction by using the current heat flow direction, correcting the current heat flow density, and generating the target heat flow density; converting the target heat flow density into the working medium flow ratio, adjusting the on-off duty ratio, keeping the on-off duty ratio when the phase change interface exceeds the laying termination position, starting the adjacent heat pipe section adjustment, updating the actual form of the phase change interface, and obtaining the dynamic regulation result of the phase change interface. The application realizes the directional correction and stable promotion of the local deviation of the phase change interface by correcting the current heat flow density.

Description

Technical Field

[0001] This invention relates to the field of directional solidification control technology, and in particular to a method, equipment and medium for dynamic control of directional solidification phase change interface. Background Technology

[0002] Directional solidification, by establishing a stable temperature gradient within the melt, enables crystals to grow along specific orientations. It has been widely applied in high-temperature alloy precision casting, semiconductor purification, magnetic material preparation, and functional crystal growth. Early control technologies mainly employed furnace zone heating, bottom cooling, pull-out speed adjustment, and insulation structure optimization. Subsequently, methods such as liquid metal cooling, fluidized bed cooling, point cold sources, rapid solidification, electromagnetic stirring, and external magnetic field assistance were gradually developed. With the development of multiphysics numerical simulation, in-situ detection, and intelligent control technologies, research focus has further shifted to the coupling relationship between temperature field, flow field, solute transport, and grain evolution, in order to achieve synergistic control of solidification front stability and casting microstructure and properties.

[0003] Existing directional solidification typically employs sheet heating elements and large-area induction heating to construct a temperature field, and combines overall cooling intensity and pulling parameters to maintain solidification conditions. Due to factors such as wide heating range, large thermal inertia, and slow start-stop response, the heat exchange state of different spatial regions is difficult to adjust independently, and local temperature changes are difficult to suppress in a timely manner. This can easily lead to lag in the control of the solidification front morphology, reduce the stability of the solidification process, and make it difficult to balance the overall thermal field regulation with local control precision and dynamic response speed. Summary of the Invention

[0004] In view of the above-mentioned existing problems, the present invention provides a method for dynamic control of directional solidification phase change interface to solve the problem that it is difficult to balance local control accuracy and dynamic response speed in overall thermal field regulation.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for dynamic control of directional solidification phase change interfaces, comprising: The heat dissipation from solidification at the bottom of the crucible is transferred to the heat pipe section on the side wall of the crucible. The current heat flux density is calculated using the working fluid flow rate and the temperature difference between the inlet and outlet of the working fluid in each heat pipe section, and the current heat flux direction is assigned. The position of the phase change interface is located simultaneously, and the actual morphology of the phase change interface is obtained. By comparing the actual shape of the phase transition interface with the set shape of the phase transition interface, the interface lead distance and interface lag distance are obtained. The target heat flux direction required to reduce the interface lead distance and interface lag distance is determined by using the current heat flux direction. The current heat flux density is then corrected along the target heat flux direction to generate the target heat flux density. The target heat flux density is converted into a working fluid flow rate ratio, and the on / off duty cycle of the electronically controlled throttle valve is adjusted using the working fluid flow rate ratio. When the phase change interface exceeds the laying termination position of the current heat pipe section, the on / off duty cycle of the current electronically controlled throttle valve is maintained, and the adjustment of the adjacent heat pipe section is initiated to update the actual shape of the phase change interface until the interface lead distance and interface lag distance disappear, thus obtaining the dynamic control result of the phase change interface.

[0006] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the specific steps for calculating the current heat flux density are as follows: Based on the inlet and outlet temperature measurement positions of each heat pipe section, the working fluid inlet temperature and working fluid outlet temperature are obtained, and the temperature difference between the working fluid inlet temperature and the working fluid outlet temperature is determined as the working fluid inlet and outlet temperature difference. Within the temperature range covered by the temperature difference between the inlet and outlet of the working fluid, the flow rate of the working fluid and the temperature difference between the inlet and outlet of the working fluid are converted into the heat exchange per unit time of each heat pipe section by the isobaric specific heat capacity of the working fluid. The heat exchange rate per unit time is converted to area to obtain the current heat flux density.

[0007] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, wherein: the current heat flow direction is defined as the direction of the heat pipe section pointing to the crucible sidewall for a heat pipe section whose working fluid inlet temperature is higher than the working fluid outlet temperature, and the direction from the crucible sidewall to the heat pipe section is defined as the current heat flow direction for a heat pipe section whose working fluid inlet temperature is lower than the working fluid outlet temperature. The location of the phase change interface is determined by arranging temperature sampling positions and sampling temperatures according to the preset solidification growth direction, selecting a temperature change section, and determining the phase change interface position based on the change ratio of the sampling temperatures at both ends of the selected temperature change section. The actual shape of the phase change interface is obtained by using the spatial coordinates of each phase change interface position in the crucible as the sorting reference, inserting interpolation positions between adjacent phase change interface positions, and merging the sorted phase change interface positions with the interpolation positions to obtain the actual shape of the phase change interface.

[0008] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the specific steps for obtaining the interface lead distance and interface lag distance are as follows: Read the pre-stored phase change interface setting pattern in the directional solidification process requirements, and select the setting interface position at the same spatial position as the crucible cross-section from the phase change interface setting pattern. Using the preset solidification growth direction as the criterion for determining the positional order, the phase change interface position is compared with the set interface position, and the distance by which the phase change interface position exceeds the set interface position along the preset solidification growth direction is recorded as the interface lead distance. The distance between the phase change interface position and the set interface position is recorded as the interface hysteresis distance.

[0009] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the specific steps of determining the target heat flow direction required to reduce the interface lead distance and interface lag distance using the current heat flow direction are as follows: Read the starting and ending positions of each heat pipe segment on the crucible sidewall, and select the heat pipe segment containing the positions of interface lead distance and interface lag distance as the heat pipe segment to be adjusted. In the heat pipe section to be adjusted, when only the interface leading distance position is covered, the direction from the heat pipe section to the crucible sidewall is determined as the candidate target heat flow direction; when only the interface lagging distance position is covered, the direction from the crucible sidewall to the heat pipe section is determined as the candidate target heat flow direction. When both interface lead distance and interface lag distance exist simultaneously, the direction of heat flow of the candidate target is determined by comparing the lengths of the interface lead distance and the interface lag distance. The candidate target heat flow direction is checked segment by segment against the current heat flow direction. When the directions are the same, the current heat flow direction is retained and used as the target heat flow direction. When the directions are opposite, the candidate target heat flow direction is used to replace the current heat flow direction to obtain the target heat flow direction.

[0010] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the specific steps for generating the target heat flux density are as follows: By utilizing the proportions of interface lead distance and interface lag distance in the laying length of the heat pipe section to be adjusted, the current heat flux density is converted into a heat flux density correction amount. The target heat flow direction is compared with the current heat flow direction. When the directions are the same, the current heat flow density of the heat pipe section to be adjusted is increased by the heat flow density correction amount. When the directions are opposite, the current heat flow density of the heat pipe section to be adjusted is reduced to zero, and the heat flow density correction amount is determined as the heat flow density of the heat pipe section to be adjusted along the target heat flow direction. The increased heat flux density and the reverse-determined heat flux density are used together as the target heat flux density.

[0011] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the working fluid flow rate ratio is calculated based on the target heat flux density, effective heat exchange area, average isobaric specific heat capacity and working fluid inlet and outlet temperature difference of each heat pipe section to be adjusted, and the working fluid flow rate ratio is determined according to the proportion of each target working fluid flow rate in the total amount.

[0012] As a preferred embodiment of the directional solidification phase change interface dynamic control method of the present invention, the specific steps of initiating the adjustment of adjacent heat pipe sections and updating the actual morphology of the phase change interface are as follows: When the phase change interface position crosses the termination position of the current heat pipe segment on the crucible sidewall, the adjacent heat pipe segment is activated. While keeping the on / off duty cycle of the electronically controlled throttle valve of the current heat pipe section constant, the on / off duty cycle of the electronically controlled throttle valve of the adjacent heat pipe section is adjusted by the ratio of the working fluid flow of the adjacent heat pipe section. The phase change interface position is repositioned at the sampling time after the adjacent heat pipe section is started, and the original phase change interface position is replaced with the repositioned phase change interface position, and the actual shape of the phase change interface is updated. The updated phase change interface actual form is compared with the phase change interface set form to obtain the interface lead distance and interface lag distance again. The target heat flux direction and target heat flux density are then regenerated using the newly obtained interface lead distance and interface lag distance until both interface lead distance and interface lag distance disappear.

[0013] In a second aspect, the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein when the computer program is executed by the processor, it implements any step of the directional solidification phase change interface dynamic control method as described in the first aspect of the present invention.

[0014] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the method for dynamic control of directional solidification phase change interface as described in the first aspect of the present invention.

[0015] The beneficial effects of this invention are as follows: By correcting the current heat flux density, it achieves directional correction and stable advancement of local deviations at the phase change interface, suppressing excessively rapid or slow local advancement of the solidification front, reducing reverse adjustment, heat mismatch, and reciprocating fluctuations of the interface, allowing the solidification front to gradually recover to the expected morphology, maintaining the coordination of axial temperature gradient and radial heat distribution, reducing the probability of interface protrusions, depressions, and continuous offsets, and enhancing the response sensitivity and operational stability of the directional solidification process; at the same time, it can alleviate the thermal field distortion caused by differences in local solidification rates, keep the solidification process at different spatial locations coordinated, reduce grain growth direction offset and local microstructure inhomogeneity, improve the continuity of solidification structure, interface morphology consistency, and forming quality, and provide a reliable basis for the stable preparation of castings with complex cross-sections and long-dimensional materials. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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.

[0017] Figure 1 This is a flowchart of a method for dynamic control of the interface of directional solidification phase change.

[0018] Figure 2 A flowchart for obtaining the current heat flux density.

[0019] Figure 3 A flowchart for obtaining the actual shape of the phase transition interface.

[0020] Figure 4 A flowchart for obtaining the target heat flow direction.

[0021] Figure 5 This is a comparison chart of the standard deviation of phase transition interface morphology and local stability.

[0022] Figure 6 This is a comparison chart showing the current heat flux density and the corrected target heat flux density. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0026] Reference Figures 1-6 As one embodiment of the present invention, this embodiment provides a method for dynamic control of directional solidification phase change interface, comprising the following steps: S1. The liquid working fluid that absorbs the heat dissipation from the solidification at the bottom of the crucible is transported to the heat pipe section on the side wall of the crucible. The current heat flux density is calculated using the working fluid flow rate and the temperature difference between the inlet and outlet of the working fluid in each heat pipe section, and the current heat flux direction is assigned. The position of the phase change interface is located simultaneously, and the actual morphology of the phase change interface is obtained.

[0027] S1.1 The bottom heating coil is embedded in the thermally conductive filling material at the bottom of the crucible, so that the outer wall of the bottom heating coil is in continuous contact with the thermally conductive filling material; the outlet of the bottom heating coil is connected to the inlet of the heat pipe section laid along the side wall of the crucible, and the outlet of the heat pipe section is connected to the temperature control radiator, the working fluid pump and the bottom heating coil inlet in sequence through the return pipeline to form a closed pipeline for the circulation of liquid working fluid.

[0028] The heat dissipation generated by directional solidification is transferred through the bottom wall of the crucible to the thermally conductive filling material, and then from the thermally conductive filling material to the outer wall of the bottom heat coil. The liquid working fluid in the bottom heat coil absorbs the heat dissipation during solidification. The electrically controlled throttle valve on the heat pipe section involved in the heat dissipation transfer is turned on, and the working fluid pump drives the liquid working fluid from the outlet of the bottom heat coil to the inlet of the heat pipe section, and flows along the laying direction of the heat pipe section through the crucible sidewall, so that the liquid working fluid absorbing the heat dissipation enters the heat pipe section on the sidewall of the crucible. The direction of heat transfer between the heat pipe section and the crucible sidewall is determined based on the temperature change of the liquid working fluid after flowing through the heat pipe section. After the liquid working fluid flows out of the heat pipe section, it enters the temperature-controlled radiator, and after temperature regulation, it flows back into the bottom heat coil to maintain the continuous transfer of heat dissipation during solidification.

[0029] Before starting the working fluid pump, the bottom hot coil, the hot pipe section, and the return pipe are filled with liquid working fluid and residual gas is discharged. The liquid working fluid remains liquid at the directional solidification working temperature and circulating pressure, and the bottom hot coil, the hot pipe section, and the return pipe remain sealed under the circulating pressure.

[0030] It should be noted that in this embodiment, the working fluid flow rate refers to the working fluid mass flow rate; the current heat flux density and the target heat flux density are both represented by non-negative values ​​without directional signs, and the current heat flux direction and the target heat flux direction are recorded separately.

[0031] The preset solidification growth direction is taken from the requirements of the directional solidification process and serves as the criterion for determining the order of phase change interface position advancement; the current heat flow direction represents the actual heat transfer direction between the heat pipe section and the crucible sidewall and is not used as the criterion for determining the order of phase change interface position advancement.

[0032] The preset solidification growth direction is determined before the start of directional solidification based on the initial position of the phase change interface and the expected advancement position specified in the directional solidification process. The spatial direction from the initial position of the phase change interface to the expected advancement position is taken as the preset solidification growth direction and remains unchanged during the directional solidification process.

[0033] S1.2 Calculate the current heat flux density using the working fluid flow rate and the temperature difference between the inlet and outlet of each heat pipe section, specifically: S1.2.1. Based on the inlet and outlet temperature measurement positions of each heat pipe section, obtain the working fluid inlet temperature and working fluid outlet temperature, and determine the temperature difference between the working fluid inlet temperature and the working fluid outlet temperature as the working fluid inlet and outlet temperature difference, specifically: Temperature sensors are installed at the inlet and outlet temperature measurement positions of each heat pipe section. The internal flow volume is recorded as the space between the inlet and outlet temperature measurement positions when the pipe is filled with working fluid.

[0034] The temperature sensor at the entrance temperature measurement point at the sampling time Output the first The working fluid inlet temperature of each heat pipe section, from the sampling time. Start reading the first The working fluid mass flow rate and working fluid density of each heat pipe section are calculated, and the working fluid mass flow rate is converted to the working fluid volume flow rate using the following formula: ; In the formula, It represents the volumetric flow rate of the working fluid, and its value is not less than zero. Its dimension is cubic meters per second. This represents the mass flow rate of the working fluid, with a value not less than zero, and the dimension is kilograms per second. This represents the density of the working fluid, with a value greater than zero and a dimension of kilograms per cubic meter. Indicates the heat pipe segment number; This indicates the mass flow rate sampling interval number.

[0035] The working fluid density is taken from the working fluid property record and obtained by linear interpolation based on the current sampling temperature.

[0036] The trapezoidal accumulation method is used to accumulate data from the sampling time. Initial cumulative flow volume of the working fluid: ; In the formula, This indicates the cumulative volume of the working fluid flowing through, with the dimension of cubic meters; Indicates the first The duration of each sampling interval, in seconds; Indicates from the sampling time The number of sampling intervals to be counted at the beginning.

[0037] The cumulative flow volume of the working fluid reached the first time. The sampling time of the internal flow volume of each heat pipe section is recorded as the outlet sampling time. and read the exit sampling time The working fluid outlet temperature is obtained by pairing the working fluid outlet temperature at the sampling time with the working fluid inlet temperature at the initial sampling time according to the nominal flow duration formed by the internal flow volume of the heat pipe section, and obtaining the working fluid inlet temperature and working fluid outlet temperature corresponding to the same flow time interval.

[0038] The specific method for obtaining the temperature difference judgment tolerance is as follows: Read the maximum measurement error of the inlet temperature measuring position probe and the maximum measurement error of the outlet temperature measuring position probe from the calibration records of the inlet temperature measuring position probe and the outlet temperature measuring position probe respectively, and take the sum of the maximum measurement error of the inlet temperature measuring position probe and the maximum measurement error of the outlet temperature measuring position probe as the temperature difference judgment tolerance.

[0039] Compare the inlet temperature and outlet temperature of the working fluid, and define the temperature interval between them as the inlet and outlet temperature difference of the working fluid. If the inlet temperature is higher than the outlet temperature and the inlet and outlet temperature difference is greater than the temperature difference tolerance, the working fluid temperature decreases after flowing through the heat pipe section. If the outlet temperature is higher than the inlet temperature and the inlet and outlet temperature difference is greater than the temperature difference tolerance, the working fluid temperature increases after flowing through the heat pipe section. If the inlet and outlet temperature difference is not greater than the temperature difference tolerance, the inlet and outlet temperature difference is recorded as zero.

[0040] The temperature difference judgment tolerance is expressed in Kelvin. For example, when the maximum measurement error of the temperature sensing probe at the inlet and outlet temperature sensing probes is both ±0.5 Kelvin, the temperature difference judgment tolerance is 1 Kelvin.

[0041] S1.2.2 Within the temperature range covered by the temperature difference between the inlet and outlet of the working fluid, the flow rate of the working fluid and the temperature difference between the inlet and outlet of the working fluid are converted into the heat exchange per unit time of each heat pipe section based on the isobaric specific heat capacity of the working fluid. Specifically: The working fluid flow rate is continuously output by a mass flow meter installed at the inlet side of each heat pipe section. The mass flow meter, the temperature sensing probe at the inlet temperature measurement position, and the temperature sensing probe at the outlet temperature measurement position all use the same sampling clock.

[0042] The working fluid inlet temperature and working fluid outlet temperature use the temperature records formed in the previous step based on the pairing of internal flow volumes. The mass flow meter records the mass flow rate sampling value between the sampling time of the working fluid inlet temperature and the sampling time of the paired working fluid outlet temperature, and forms the average mass flow rate according to the duration corresponding to each mass flow rate sampling value.

[0043] The time from the sampling time of the working fluid inlet temperature to the sampling time of the working fluid outlet temperature is divided into multiple mass flow sampling intervals.

[0044] The average working fluid flow rate for each mass flow rate sampling interval is the average of the mass flow rate at the beginning of the sampling interval and the mass flow rate at the end of the sampling interval.

[0045] Using the duration of each mass flow sampling interval as a weight, the average working fluid flow rate of each sampling interval is time-weighted and summarized to obtain the average working fluid flow rate between the sampling time of the working fluid inlet temperature and the sampling time of the working fluid outlet temperature.

[0046] The temperature difference between the inlet and outlet of the working fluid is calculated using the temperature interval between the paired inlet and outlet temperatures. The relative relative temperatures of the inlet and outlet temperatures are reserved separately for subsequent assignment of the current heat flow direction. The isobaric specific heat capacity of the working fluid is taken from the working fluid property parameter table provided by the working fluid manufacturer. The working fluid property parameter table at least records the working fluid name, temperature points, isobaric specific heat capacity, and applicable physical state. The isobaric specific heat capacity records within the temperature range covered by the inlet and outlet temperature difference are first arranged from low to high according to the temperature points. Then, weights are assigned according to the temperature span occupied by each adjacent temperature point to form the average isobaric specific heat capacity.

[0047] Under the conditions that the working fluid remains in a liquid state, no phase change occurs within the heat pipe section, and the changes in kinetic and potential energy are negligible, the heat transfer per unit time can be obtained based on the flow sensible heat equilibrium relationship, using the following formula: ; In the formula, Indicates the first The heat exchange rate per unit time of each heat pipe segment; Indicates the mass flow rate of the working fluid; This represents the average isobaric specific heat capacity of the working fluid within the inlet and outlet temperature range; Indicates the inlet temperature of the working fluid. Indicates the outlet temperature of the working fluid. This indicates the sequence number of the heat pipe segment.

[0048] For example, if the sample values ​​are an average mass flow rate of 0.02 kg / s, an average constant pressure specific heat capacity of 1500 joules per kilogram of Kelvin, and a working fluid inlet and outlet temperature difference of 8 Kelvin, then the heat exchange per unit time is 240 watts.

[0049] When the working fluid flow rate is zero, the heat exchange per unit time is recorded as zero. If the mass flow rate sampling value is missing, the mass flow rate exceeds the mass flow rate measurement range, the mass flow direction deviates from the predetermined circulation direction, the working fluid inlet temperature and the working fluid outlet temperature are not properly matched, the working fluid property parameter table does not cover the corresponding temperature range, or the working fluid inlet temperature and the working fluid outlet temperature exceed the stable liquid phase range of the liquid working fluid, no heat exchange per unit time will be generated in this sampling cycle. The heat exchange will be recalculated after the next set of complete sampling values ​​meets the aforementioned conditions.

[0050] The heat exchange per unit time is calculated based on the effective heat exchange area of ​​each heat pipe section, and converted into heat exchange per unit area per unit time, which is then used as the current heat flux density for the next step.

[0051] S1.2.3. Calculate the heat exchange per unit time by area conversion to obtain the current heat flux density. The formula is: ; In the formula, For the first The current heat flux density of each heat pipe segment; For the first The effective heat exchange area of ​​each heat pipe section.

[0052] It should be noted that the effective heat exchange area is the surface area where the outer wall of each heat pipe section actually contacts and exchanges heat with the thermally conductive filling material of the crucible sidewall between the starting and ending positions of each heat pipe section.

[0053] The effective heat exchange area is determined from the construction drawings and installation records based on the outer diameter, laying length, and actual contact length of each heat pipe section embedded in the crucible sidewall. Electrically controlled throttle valves, pipe joints, insulation covering sections, and exposed sections that do not contact the crucible sidewall are not included in the effective heat exchange area.

[0054] When the effective heat exchange area is missing, the recorded value of the effective heat exchange area is not greater than zero, or the value recorded on the construction drawings is inconsistent with the value recorded in the installation records, the current heat flux density is suspended, and the original effective heat exchange area is replaced with the actual contact surface area measured on site before recalculation.

[0055] S1.3. Use the working fluid inlet temperature, working fluid outlet temperature and temperature difference to determine the tolerance and assign the current heat flow direction.

[0056] When the working fluid inlet temperature is higher than the working fluid outlet temperature, and the temperature difference between the working fluid inlet and outlet is greater than the temperature difference judgment tolerance, the direction from the heat pipe section to the crucible sidewall will be determined as the current heat flow direction. When the working fluid outlet temperature is higher than the working fluid inlet temperature, and the temperature difference between the working fluid inlet and outlet is greater than the temperature difference judgment tolerance, the direction from the crucible sidewall to the heat pipe section will be determined as the current heat flow direction. When the temperature difference between the working fluid inlet and outlet is not greater than the temperature difference judgment tolerance, the current heat flux density will be recorded as zero, no new current heat flow direction will be formed, and the working fluid inlet temperature and working fluid outlet temperature will be obtained again at the next sampling time.

[0057] S1.4. Arrange temperature sampling positions and sampling temperatures according to the preset solidification growth direction, select temperature change sections, and determine the phase transition interface position based on the ratio of temperature change at both ends of the selected temperature change section, specifically: Along the heat exchange location of each heat pipe section, two or more temperature sensors are sequentially installed in the crucible along the preset solidification growth direction. The installation coordinates of the temperature sensors are used as the temperature sampling positions, and all temperature sensors output the sampling temperature at the same sampling time.

[0058] Each temperature sampling record includes the temperature sensor number, temperature sampling location, sampling time, sampling temperature, and the sequence number of the heat pipe segment to which it belongs. The temperature sensor number ensures that the temperature sampling location and sampling temperature are uniquely associated.

[0059] Delete temperature sampling records that are missing, exceed the range of the temperature sensor, or are repeatedly written by the same temperature sensor at the same sampling time. Arrange temperature sampling records at different sampling times separately. If fewer than two temperature sampling positions are retained, the current sampling time will not form a phase change interface position.

[0060] Temperature sampling positions are arranged sequentially according to the preset solidification growth direction, and the sampling temperatures are arranged synchronously with their respective temperature sampling positions. Adjacent sampling temperatures are compared with the solidification temperatures recorded in the directional solidification process requirements segment by segment, and the temperature change segment is determined between the adjacent temperature sampling positions at both ends of the solidification temperature.

[0061] When there is only one temperature change segment at the current sampling time, the determined temperature change segment is selected; when there are two or more temperature change segments at the current sampling time, the temperature change segment that is ranked first along the preset solidification growth direction is selected at the first sampling time, and the phase change interface position corresponding to each temperature change segment is obtained at subsequent sampling times. The phase change interface position with the smallest spatial distance from the phase change interface position at the previous sampling time is selected, and the corresponding temperature change segment is used as the selected temperature change segment.

[0062] The temperature sampling position that is first in the selected temperature change segment along the preset solidification growth direction is taken as the starting temperature sampling position. The temperature interval between the solidification temperature and the corresponding sampling temperature of the starting temperature sampling position is obtained, and the temperature interval between the sampling temperatures at both ends of the selected temperature change segment is obtained. The spatial distance between the temperature sampling positions at both ends of the selected temperature change segment is calculated by using the ratio of the two temperature intervals mentioned above. The calculated spatial position is obtained from the starting temperature sampling position along the preset solidification growth direction, and the spatial position is determined as the phase change interface position. If there is no temperature change segment at the current sampling time, no phase change interface position is formed.

[0063] S1.5. Using the spatial coordinates of each phase transition interface position within the crucible as the sorting criterion, interpolation positions are added between adjacent phase transition interface positions. The sorted phase transition interface positions and the interpolation positions are then merged to form the actual shape of the phase transition interface, specifically: Multiple temperature sampling sections are set along the circumference of the crucible to collect the positions of each phase change interface formed at the same sampling time. Each phase change interface position record is written with the phase change interface position number, the corresponding temperature sampling section number, the corresponding heat pipe section number, the temperature sampling positions at both ends of the temperature change section used to form the phase change interface position, and the spatial coordinates of the phase change interface position in the crucible. Phase change interface position records with missing spatial coordinates are not included in the arrangement. Only one phase change interface position record with completely overlapping spatial coordinates is retained. Phase change interface positions formed at different sampling times are processed separately.

[0064] Each temperature sampling section uses the same crucible spatial coordinate reference and is arranged sequentially along the circumference of the crucible. Within each temperature sampling section, the phase change interface positions are arranged in spatial order from one side wall through the crucible center to the opposite side wall. Piecewise linear interpolation is used between adjacent phase change interface positions. The interpolation interval of the section is the installation interval of adjacent temperature sampling positions within the corresponding temperature sampling section. The lateral, longitudinal, and height coordinates of the interpolation position of the section are determined according to the distance ratio between the two phase change interface positions, forming a point list of phase change interface positions for each temperature sampling section.

[0065] Within the same temperature sampling section, piecewise linear interpolation is used between adjacent phase change interface positions. The interpolation interval is the installation spacing between adjacent temperature sampling positions. The horizontal, vertical, and height coordinates of the interpolation position are all taken according to the proportion of the distance occupied by the interpolation position between the two phase change interface positions. If the distance between adjacent phase change interface positions is less than one interpolation interval, no interpolation position is added.

[0066] The two positions to be interpolated need to be filled with padding. When interpolating at a certain number of positions, the distance between two interpolation positions is divided into... There are 16 equidistant intervals, and the interpolation positions are numbered in order from the previous interpolation position to the next interpolation position. Interpolation ratio corresponding to each interpolation position for ; In the formula, Indicates the sequential number of the current interpolation position. This indicates the total number of interpolation positions that need to be added between two positions to be interpolated.

[0067] Let the spatial coordinates of the two locations to be interpolated be respectively and The interpolation position located between the two phase transition interfaces is: ; In the formula, This represents the proportion of the distance between the two interpolation positions, and its value ranges from zero to one. , and All are spatial coordinate vectors, with the unit being meters.

[0068] According to the above piecewise linear interpolation method, interpolation positions are added between adjacent phase change interface positions in each temperature sampling section to form a sequence of phase change interface positions for each temperature sampling section; then, according to the circumferential arrangement order of the temperature sampling sections, circumferential interpolation positions are added between the phase change interface positions and the interpolation positions in adjacent circumferential temperature sampling sections that are in the same spatial order.

[0069] The cross-sectional interpolation position is written with the corresponding temperature sampling section number, spatial coordinates, sampling time, and corresponding heat pipe section number. The circumferential interpolation position is written with the adjacent temperature sampling section number, spatial coordinates, and sampling time. The phase change interface position, cross-sectional interpolation position, and circumferential interpolation position of each temperature sampling section are arranged and connected according to the circumferential order of the temperature sampling sections and the spatial order within each temperature sampling section to form the actual shape of the phase change interface.

[0070] If there are fewer than two temperature sampling sections formed at the same sampling time, the actual shape of the phase transition interface is not formed, and the phase transition interface position of each temperature sampling section is re-formed at the next sampling time.

[0071] S2. Compare the actual shape of the phase change interface with the set shape of the phase change interface to obtain the interface lead distance and interface lag distance.

[0072] S2.1. Read the pre-stored phase change interface settings in the directional solidification process requirements, and select the interface position at the same spatial position as the crucible cross-section from the phase change interface settings. Specifically: Before directional solidification begins, the phase change interface setting pattern given by the directional solidification process is written into the controller storage area. The phase change interface setting pattern consists of the setting interface positions arranged sequentially along the crucible cross-section. Each setting interface position record includes the solidification stage identifier, cross-sectional coordinates, height coordinates, and setting interface position number.

[0073] The phase change interface setting form with the same identifier as the current solidification stage is called, the crucible space coordinate reference used to form the actual phase change interface form is adopted, and the cross-sectional coordinates of the phase change interface position are used as the value coordinates of the setting interface position.

[0074] When the coordinates of the selected value are the same as the cross-sectional coordinates in the setting interface position record, the height coordinates in the same cross-sectional coordinate record are used to form the setting interface position.

[0075] When the reference coordinates are located between the cross-sectional coordinates of two adjacent set interface positions, the two height coordinates are linearly interpolated according to the distance ratio between the reference coordinates and the two cross-sectional coordinates, and the interpolated height and the reference coordinates are combined to form the set interface position.

[0076] When the coordinate value exceeds the cross-sectional area covered by the first and last set interface positions, no set interface position is generated, and the distance comparison of the corresponding phase change interface position is stopped.

[0077] After the values ​​are obtained, the phase change interface position and the set interface position are saved according to the arrangement order in the actual shape of the phase change interface, so that the phase change interface position and the set interface position have the same cross-sectional coordinates.

[0078] S2.2. Using the preset solidification growth direction as the criterion for determining the positional order, compare the phase change interface position with the set interface position. Record the distance by which the phase change interface position exceeds the set interface position along the preset solidification growth direction as the interface lead distance, and record the distance by which the phase change interface position does not reach the set interface position as the interface lag distance. Specifically: Using the preset solidification growth direction as the criterion for determining the advancement relationship between the phase transformation interface position and the set interface position, the phase transformation interface positions at the same spatial position in the crucible cross-section are paired with the set interface positions. A direction line passing through the set interface position and parallel to the preset solidification growth direction is established, and the phase transformation interface position is projected onto the direction line to obtain the phase transformation interface projection position. The phase transformation interface projection position and the set interface position are compared along the preset solidification growth direction. When the phase transformation interface projection position is in front of the set interface position, the distance between the phase transformation interface projection position and the set interface position is recorded as the interface advance distance. When the phase transformation interface projection position is behind the set interface position, the distance between the phase transformation interface projection position and the set interface position is recorded as the interface lag distance. When the phase transformation interface projection position and the set interface position coincide, both the interface advance distance and the interface lag distance are recorded as zero.

[0079] It should be noted that the preset solidification growth direction is taken from the requirements of the directional solidification process. The side pointed to by the preset solidification growth direction is taken as the front, and the side opposite to the preset solidification growth direction is taken as the rear.

[0080] S3. Use the current heat flow direction to determine the target heat flow direction required to reduce the interface lead distance and interface lag distance, correct the current heat flow density along the target heat flow direction, and generate the target heat flow density.

[0081] S3.1 Determine the target heat flow direction required to reduce the interface lead distance and interface lag distance using the current heat flow direction, specifically: S3.1.1. Read the starting and ending positions of each heat pipe segment on the crucible sidewall, and select the heat pipe segment containing both the interface lead distance and interface lag distance as the heat pipe segment to be adjusted, specifically: Before directional solidification begins, based on the installation measurement records after the heat pipe section is laid, the heat pipe section number, the height coordinates of the starting position and the ending position are written into the controller storage area. The height coordinates of the starting position and the ending position are both taken from the bottom of the crucible as the coordinate starting point and measured along the solidification growth direction of the crucible.

[0082] The elevation coordinates are used as the location of the phase change interface that forms the interface lead distance, and the elevation coordinates are used as the location of the interface lag distance, so that the two types of locations use the same coordinate reference and length unit as the location of the heat pipe section laying position.

[0083] If the interface leading distance is not lower than the starting position of the same heat pipe segment and lower than the ending position of the laying, the corresponding heat pipe segment number is written into the record of the heat pipe segment to be adjusted. If the interface lagging distance meets the same section condition, the corresponding heat pipe segment number is written in the same way.

[0084] When the same heat pipe segment contains two or more locations of interface lead distance, all interface lead distances and their corresponding locations are retained according to the spatial order of the crucible cross-section to form an interface lead distance group; when the same heat pipe segment contains two or more locations of interface lag distance, an interface lag distance group is formed in the same way.

[0085] The same heat pipe segment contains both the location of the interface lead distance and the location of the interface lag distance. Only one record of the heat pipe segment to be adjusted is saved, and the interface lead distance, the location of the interface lead distance, the interface lag distance, and the location of the interface lag distance are written into the record of the heat pipe segment to be adjusted.

[0086] Adjacent heat pipe segments sharing a common boundary are included in the heat pipe segment whose laying start position is located at the common boundary, and the laying end position of the heat pipe segment at the end of the laying sequence is included in the heat pipe segment at the end of the laying sequence.

[0087] The heat pipe segments whose interface leading distance and interface lagging distance are not covered are not written into the heat pipe segment record to be adjusted. The resulting heat pipe segment record to be adjusted is used to obtain the candidate target heat flow direction in the next step.

[0088] S3.1.2 In the heat pipe section to be adjusted, when only the interface leading distance is covered, the direction from the heat pipe section to the crucible sidewall is determined as the candidate target heat flow direction; when only the interface lagging distance is covered, the direction from the crucible sidewall to the heat pipe section is determined as the candidate target heat flow direction, specifically: The system retrieves the heat pipe segment number, interface lead distance, interface lead distance location, interface lag distance, and interface lag distance location from the heat pipe segment record to be adjusted. Since the interface lead distance and interface lead distance location have been written, but the interface lag distance and interface lag distance location have not been written, it indicates that the heat pipe segment to be adjusted only covers the interface lead distance location. The direction in which heat is transferred from the working fluid inside the heat pipe segment through the heat pipe segment wall to the crucible sidewall is written as the candidate target heat flow direction.

[0089] The interface lag distance and its location have been written, while the interface lead distance and its location have not been written. This indicates that the heat pipe section to be adjusted only covers the location of the interface lag distance. The direction in which heat is transferred from the crucible sidewall through the heat pipe section wall to the working fluid inside the heat pipe section is written as the candidate target heat flow direction.

[0090] S3.1.3 When both interface lead distance and interface lag distance exist simultaneously, the direction of heat flow for the candidate target is determined by comparing the lengths of the interface lead distance and the interface lag distance. Specifically: When both phase change interface locations with interface lead distance and interface lag distance exist simultaneously within the same heat pipe section to be adjusted, the interface lead distances of all heat pipe sections to be adjusted are aggregated into a total interface lead distance, and the interface lag distances of all heat pipe sections to be adjusted are aggregated into a total interface lag distance.

[0091] When the total leading distance of the interface is greater than the total lagging distance of the interface, the direction of heat transfer from the heat pipe section to the sidewall of the crucible is recorded as the candidate target heat flow direction; when the total lagging distance of the interface is greater than the total leading distance of the interface, the direction of heat transfer from the sidewall of the crucible to the heat pipe section is recorded as the candidate target heat flow direction.

[0092] When the total leading distance and the total lagging distance of the interface are the same, no candidate target heat flow direction is generated, the current heat flow density remains unchanged, and the leading distance and lagging distance of the interface are obtained again at the next sampling time.

[0093] S3.1.4. Verify the candidate target heat flow direction against the current heat flow direction segment by segment. When the directions are the same, retain the current heat flow direction and use it as the target heat flow direction. When the directions are opposite, replace the current heat flow direction with the candidate target heat flow direction to obtain the target heat flow direction. Specifically: Using the heat pipe segment number to be adjusted as an index, the candidate target heat flow direction and the current heat flow direction of the same heat pipe segment to be adjusted are compared segment by segment. When both the candidate target heat flow direction and the current heat flow direction point from the heat pipe segment to the crucible sidewall, the current heat flow direction is retained and recorded as the target heat flow direction.

[0094] When both the candidate target heat flow direction and the current heat flow direction point from the crucible sidewall to the heat pipe section, the current heat flow direction is retained and recorded as the target heat flow direction; when the candidate target heat flow direction points from the heat pipe section to the crucible sidewall and the current heat flow direction points from the crucible sidewall to the heat pipe section, the candidate target heat flow direction replaces the current heat flow direction.

[0095] When the candidate target heat flow direction points from the crucible sidewall to the heat pipe section, and the current heat flow direction points from the heat pipe section to the crucible sidewall, the candidate target heat flow direction is still used to replace the current heat flow direction.

[0096] When the current heat flux density is zero and the current heat flux direction is not assigned a value, the candidate target heat flux direction is directly recorded as the target heat flux direction.

[0097] S3.1.5 Adjust the temperature setting of the temperature control radiator so that the relationship between the working fluid inlet temperature and the working fluid outlet temperature of each heat pipe section to be adjusted meets the target heat flow direction.

[0098] Before directional solidification begins, multiple temperature calibration points are sequentially set within the common range of the stable liquid phase temperature of the liquid working fluid, the allowable temperature range of the temperature controller radiator, and the allowable working fluid temperature range of the directional solidification process, according to the minimum temperature adjustment resolution of the temperature controller radiator.

[0099] At each temperature calibration point, the electronically controlled throttle valve of each heat pipe section is kept at the minimum controllable on / off duty cycle, and the working fluid inlet temperature and working fluid outlet temperature of each heat pipe section are obtained after completing one control cycle, forming a calibration relationship between the temperature setpoint of the temperature control radiator, the heat pipe section number, the working fluid inlet temperature, the working fluid outlet temperature and the actual heat flow direction.

[0100] When the target heat flow direction is from the heat pipe section to the crucible sidewall, select a temperature setting value from the calibration relationship that satisfies the working fluid inlet temperature minus the working fluid outlet temperature being greater than the temperature difference judgment tolerance.

[0101] When the target heat flow direction is from the crucible sidewall to the heat pipe section, select a temperature setting value from the calibration relationship that satisfies the working fluid outlet temperature minus the working fluid inlet temperature being greater than the temperature difference judgment tolerance.

[0102] When two target heat flow directions exist simultaneously, first select the temperature setting value that can make all the heat pipe sections to be adjusted meet their respective target heat flow directions; if there are multiple temperature setting values ​​that meet the conditions, select the temperature setting value with the smallest difference from the current temperature setting value.

[0103] If there is no temperature setpoint that can simultaneously satisfy all target heat flow directions, the target interface distances from the heat pipe section to the crucible sidewall and from the crucible sidewall to the heat pipe section are collected separately. In the current control cycle, the target heat flow direction with the larger target interface distance collection result is executed, while the electronically controlled throttle valve corresponding to the other target heat flow direction is kept closed. After obtaining the interface lead distance and interface lag distance again in the next control cycle, the target heat flow direction determination is executed again.

[0104] After the temperature-controlled radiator reaches the selected temperature setpoint, the heat pipe section to be adjusted runs at the minimum controllable on / off duty cycle for one control cycle, and the working fluid inlet temperature and working fluid outlet temperature are obtained again. When the actual heat flow direction is consistent with the target heat flow direction, the current heat flux density correction is entered. When the actual heat flow direction is inconsistent with the target heat flow direction, the temperature adjustment resolution is adjusted along the temperature change direction required to achieve the target heat flow direction, and the verification is repeated. When the temperature setpoint reaches the boundary of the allowable adjustment range but the target heat flow direction is still not formed, the current adjustment of the corresponding heat pipe section is stopped and the direction establishment failure record is written.

[0105] S3.2. Correct the current heat flux density along the target heat flux direction to generate the target heat flux density, specifically as follows: S3.2.1. Using the proportions of interface lead distance and interface lag distance in the laying length of the heat pipe section to be adjusted, the current heat flux density is converted into a heat flux density correction amount, specifically: The current heat flux density, target heat flux direction, total interface lead distance, total interface lag distance, and laying length of the heat pipe section to be adjusted are obtained from the records of the heat pipe section to be adjusted at the same sampling time. When the target heat flux direction is from the heat pipe section to the crucible sidewall, the total interface lead distance is taken as the target interface distance. When the target heat flux direction is from the crucible sidewall to the heat pipe section, the total interface lag distance is taken as the target interface distance.

[0106] The current heat flux density is scaled according to the proportion of the target interface distance in the laying length of the heat pipe section to be adjusted, and the scaled heat flux density is recorded as the heat flux density correction amount.

[0107] When the target interface distance reaches the laying length of the heat pipe section to be adjusted, the heat flux density correction amount shall not exceed the current heat flux density. When the target interface distance is zero, the heat flux density correction amount shall be recorded as zero.

[0108] When the current heat flux density is zero, the directional solidification process requires the pre-written initial heat flux density to be converted proportionally.

[0109] S3.2.2. Compare the target heat flow direction with the current heat flow direction. If the directions are the same, increase the current heat flow density of the heat pipe section to be adjusted using the heat flow density correction amount. If the directions are opposite, reduce the current heat flow density of the heat pipe section to be adjusted to zero, and determine the heat flow density correction amount as the heat flow density of the heat pipe section to be adjusted along the target heat flow direction. Specifically: Using the heat pipe segment number to be adjusted and the sampling time as common indexes, the target heat flow direction, current heat flow direction, current heat flow density and heat flow density correction amount are obtained, and the current heat flow density and heat flow density correction amount are both taken as heat flow density values ​​without direction signs.

[0110] The target heat flow direction and the current heat flow direction both point from the heat pipe section to the crucible sidewall, or both point from the crucible sidewall to the heat pipe section. The target heat flow direction is retained, and the target heat flow density is increased by a heat flow density correction amount compared to the current heat flow density.

[0111] The target heat flow direction is opposite to the current heat flow direction. First, the heat flow density along the current heat flow direction is recorded as zero. Then, the heat flow density correction amount is used as the target heat flow density along the target heat flow direction to avoid the simultaneous existence of heat flow densities in opposite directions in the same heat pipe section to be adjusted.

[0112] If the current heat flux density is zero and the current heat flux direction is not assigned a value, the heat flux density correction amount is directly used as the target heat flux density along the target heat flux direction.

[0113] S3.2.3, The increased heat flux density and the reverse-determined heat flux density are used together as the target heat flux density.

[0114] S4. Convert the target heat flux density into a working fluid flow rate ratio, and use the working fluid flow rate ratio to adjust the on / off duty cycle of the electronically controlled throttle valve. When the phase change interface exceeds the laying termination position of the current heat pipe section, maintain the current on / off duty cycle of the electronically controlled throttle valve, and start the adjustment of the adjacent heat pipe section to update the actual shape of the phase change interface until the interface lead distance and interface lag distance disappear, and obtain the dynamic control result of the phase change interface.

[0115] S4.1 Convert the target heat flux density into a working fluid flow rate ratio, specifically as follows: Under the condition that all heat pipe sections to be adjusted use the same effective heat exchange area, the same working fluid type, and the same working fluid inlet and outlet temperature difference conversion benchmark, all records of heat pipe sections to be adjusted formed at the same sampling time are used as the conversion range. The target heat flux density and the target heat flux direction are checked according to the sequence number of the heat pipe section to be adjusted. Only one complete record is retained for duplicate records. Records with missing target heat flux density or target heat flux density less than zero are not included in this conversion.

[0116] The retained target heat flux densities are summarized as non-negative values ​​without directional signs to form the total target heat flux density. When the total target heat flux density is greater than zero, the proportion of the target heat flux density in the total target heat flux density is obtained segment by segment. The obtained proportion is recorded as the working fluid flow rate ratio of the corresponding heat pipe section to be adjusted, and all working fluid flow rate ratios are summed up to one.

[0117] When the total target heat flux density is equal to zero, the working fluid flow rate ratio of all heat pipe sections to be adjusted is recorded as zero, and the current on / off duty cycle of the electronically controlled throttle valve is maintained.

[0118] The working fluid flow rate ratio, the sequence number of the heat pipe section to be adjusted, the target heat flow direction, and the sampling time are written into the same record, so that the total working fluid flow rate can be allocated according to the working fluid flow rate ratio and the duty cycle of the electronically controlled throttle valve can be adjusted.

[0119] It should be noted that when the effective heat exchange area and working fluid heat exchange conditions of each heat pipe section to be adjusted are different, the working fluid flow rate cannot be directly allocated according to the target heat flux density ratio. Instead, the target heat flux density should be converted into the corresponding target heat exchange rate first, and then the working fluid flow rate ratio should be formed according to the target heat exchange rate ratio.

[0120] When the effective heat transfer area, average isobaric specific heat capacity, and inlet / outlet temperature difference of each heat pipe section to be adjusted are different, the target heat flux density of each heat pipe section to be adjusted is first converted into the target working fluid mass flow rate, and then the working fluid flow rate ratio is formed. The formula is as follows: ; ; In the formula, For the first The target heat flux density of the heat pipe section to be adjusted; The target working fluid mass flow rate; This represents the ratio of the working fluid flow rate. The number of heat pipe segments to be regulated that participate in the current regulation. Indicates the summation sequence number.

[0121] When all heat pipe sections to be adjusted have the same effective heat exchange area, the same average constant pressure specific heat capacity, and the same working fluid inlet and outlet temperature difference, the working fluid flow rate ratio can be formed according to the proportion of each target heat flux density in the total target heat flux density.

[0122] S4.2. Adjust the on / off duty cycle of the electrically controlled throttle valve using the working fluid flow rate ratio. When the phase change interface exceeds the laying termination position of the current heat pipe section, maintain the current on / off duty cycle of the electrically controlled throttle valve, specifically as follows: Within a fixed control cycle, the proportion of the working fluid flow rate of each heat pipe section to be adjusted is directly used as the on / off duty cycle of the corresponding electronically controlled throttle valve. The control cycle is taken from the allowable switching cycle specified in the instruction manual of the electronically controlled throttle valve.

[0123] The proportion of the opening time of the electronically controlled throttle valve in the control cycle is equal to the on / off duty cycle. The valve remains closed for the remaining time in the control cycle. It remains closed when the working fluid flow rate is zero and remains open when the working fluid flow rate is one.

[0124] The height coordinates of the corresponding phase change interface position are retrieved according to the heat pipe segment number and compared with the height coordinates of the laying end position using the same crucible spatial coordinate reference. If the height coordinates of the phase change interface position do not exceed the height coordinates of the laying end position, the on / off duty cycle of the corresponding electronically controlled throttle valve is rewritten according to the latest working fluid flow ratio. If the height coordinates of the phase change interface position exceed the height coordinates of the laying end position, the on / off duty cycle used in the last control cycle before the overshoot is saved, and the on / off duty cycle of the corresponding electronically controlled throttle valve is not rewritten in subsequent sampling times.

[0125] S4.3. Initiate adjustment of adjacent heat pipe sections to update the actual morphology of the phase change interface until the interface lead distance and interface lag distance disappear, thereby obtaining the dynamic control results of the phase change interface, specifically: S4.3.1 When the phase change interface position crosses the termination position of the current heat pipe segment on the crucible sidewall, the adjacent heat pipe segment is activated, specifically as follows: Before directional solidification begins, the heat pipe segments are numbered according to their starting positions along the solidification growth direction, and the heat pipe segments that immediately follow the current heat pipe segment in the laying sequence are recorded as adjacent heat pipe segments.

[0126] The height coordinate of the phase change interface is greater than the height coordinate of the current heat pipe section laying termination position. The duty cycle of the on / off switch of the corresponding electronically controlled throttle valve of the current heat pipe section is maintained, and the serial number of the adjacent heat pipe section is written into the heat pipe section record to be adjusted.

[0127] The target heat flow direction and target heat flow density are formed based on the interface lead distance and interface lag distance covered by adjacent heat pipe sections. The working fluid flow rate ratio obtained by converting the target heat flow density is then written into the corresponding electronically controlled throttling valve of the adjacent heat pipe section, so that the electronically controlled throttling valve changes from the closed state to perform on / off control according to the working fluid flow rate ratio, and the working fluid flows into the adjacent heat pipe section.

[0128] If the height coordinate of the phase change interface is not greater than the height coordinate of the current heat pipe segment laying termination position, the corresponding electronically controlled throttling valve of the adjacent heat pipe segment remains closed; if the current heat pipe segment is at the end of the laying sequence, the adjacent heat pipe segment number will not be written.

[0129] S4.3.2. While keeping the on / off duty cycle of the electrically controlled throttle valve in the current heat pipe section constant, adjust the on / off duty cycle of the electrically controlled throttle valve in the adjacent heat pipe section by using the ratio of the working fluid flow rate in the adjacent heat pipe section, specifically as follows: After the phase change interface position crosses the laying termination position of the current heat pipe segment, the on / off duty cycle of the electrically controlled throttle valve used in the last control cycle before crossing the current heat pipe segment is fixed and saved. Subsequent sampling results will not change the fixed on / off duty cycle. At the same time, the working fluid flow ratio of the adjacent heat pipe segment is used as the on / off duty cycle of the electrically controlled throttle valve of the adjacent heat pipe segment, so that the electrically controlled throttle valve of the adjacent heat pipe segment is opened according to the on / off duty cycle in a single control cycle and closed in the remaining time period. When the working fluid flow ratio is zero, the electrically controlled throttle valve of the adjacent heat pipe segment remains closed. When the working fluid flow ratio is one, the electrically controlled throttle valve of the adjacent heat pipe segment remains open. The adjacent heat pipe segment is not started when the working fluid flow ratio has not yet been formed.

[0130] S4.3.3. At the sampling time after the adjacent heat pipe section starts, the phase change interface position is repositioned, the original phase change interface position is replaced with the repositioned phase change interface position, and the actual morphology of the phase change interface is updated, specifically as follows: After the adjacent heat pipe sections complete the first control cycle, the sampling temperature of each temperature probe is obtained at the same sampling time. The repositioned phase change interface position is formed by using the aforementioned method of sorting the temperature sampling positions, comparing the changes in adjacent sampling temperatures, and taking the midpoint of the maximum temperature change range.

[0131] Using the crucible cross-sectional spatial position as the replacement index, when the repositioned phase change interface position has the same crucible cross-sectional spatial position as the original phase change interface position, the original phase change interface position is deleted and the repositioned phase change interface position is written. If the repositioned phase change interface position has not been formed, the original phase change interface position is retained.

[0132] After the replacement is completed, all phase transition interface positions are arranged in spatial order according to the crucible cross-section. Interpolation positions are added between adjacent phase transition interface positions using the aforementioned linear interpolation method. The sorted phase transition interface positions and interpolation positions are then merged to form the updated actual shape of the phase transition interface. The updated actual shape of the phase transition interface is used to re-obtain the interface lead distance and interface lag distance at the next sampling time.

[0133] S4.3.4. Compare the updated actual form of the phase change interface with the set form of the phase change interface, obtain the interface lead distance and interface lag distance again, and use the obtained interface lead distance and interface lag distance to regenerate the target heat flux direction and target heat flux density until the interface lead distance and interface lag distance disappear.

[0134] At the sampling moment after the adjacent heat pipe section completes a control cycle, the updated actual shape of the phase change interface and the set shape of the phase change interface are placed on the same crucible space coordinate reference. The position of the phase change interface and the set position are obtained point by point according to the same cross-sectional space position, and the interface lead distance and interface lag distance are re-formed along the current heat flow direction.

[0135] The heat pipe segments with interface lead distance and interface lag distance are rewritten into the heat pipe segment record to be adjusted. Then, the aforementioned distance collection, candidate target heat flow direction formation, direction verification and heat flow density correction methods are used to obtain the target heat flow direction and target heat flow density at the current sampling time.

[0136] After the target heat flux density is converted into the working fluid flow rate ratio, the on / off duty cycle of the corresponding electronically controlled throttle valve is rewritten. After the adjacent heat pipe section completes the next control cycle, the updated phase change interface actual shape is formed again.

[0137] At any cross-sectional spatial location, there are still interface lead distance and interface lag distance. Continue to perform phase change interface position update, distance formation, target heat flow direction generation, target heat flow density generation, and on / off duty cycle rewriting.

[0138] The phase change interface positions of all cross-sectional spatial locations coincide with the set interface positions, and the interface lead distance and interface lag distance are both zero. The on / off duty cycle of the electronically controlled throttle valve is stopped from being rewritten, and the on / off duty cycle used in the last control cycle is maintained.

[0139] At each sampling moment, the interface lead distance and interface lag distance are re-formed based on the updated actual morphology of the phase change interface, and the target heat flux direction, target heat flux density, working fluid flow ratio, and on / off duty cycle of the electronically controlled throttle valve are updated sequentially. After the interface lead distance and interface lag distance at all cross-sectional spatial positions are zero, the generation of new target heat flux density is stopped, and the current updated actual morphology of the phase change interface is recorded as the regulated phase change interface morphology. The target heat flux direction, target heat flux density, and on / off duty cycle of the electronically controlled throttle valve used by each heat pipe segment at the current sampling moment are retained. The regulated phase change interface morphology, the target heat flux direction, target heat flux density, and on / off duty cycle of the electronically controlled throttle valve of each heat pipe segment are written into the same record to form the dynamic regulation result of the phase change interface.

[0140] The example uses two heat pipe sections to be adjusted. The temperature sampling period is 1 second, the control period of the electronically controlled throttle valve is 10 seconds, the temperature difference judgment tolerance is 1 Kelvin, the allowable interface deviation is 0.002 meters, the laying length of the two heat pipe sections to be adjusted is 0.1 meters, the effective heat exchange area is 0.03 square meters, the average isobaric specific heat capacity is 1500 joules per kilogram Kelvin, and the upper limit of heat flux density is 12000 watts per square meter.

[0141] The internal flow volume of the first heat pipe section to be adjusted is 0.00012 cubic meters, the average working fluid mass flow rate is 0.02 kg / s, the average working fluid density is 850 kg / m³, and the time required for the cumulative working fluid flow volume to reach the internal flow volume is approximately 5.1 seconds.

[0142] The working fluid inlet temperature is 420 Kelvin, the paired working fluid outlet temperature is 412 Kelvin, the working fluid inlet and outlet temperature difference is 8 Kelvin, the heat exchange per unit time is 240 W, the current heat flux density is 8000 W per square meter, and the current heat flow direction is from the first heat pipe section to be adjusted to the crucible sidewall.

[0143] The elevation coordinates of the temperature sampling locations for the first heat pipe section to be adjusted are 0.18 m, 0.19 m, 0.20 m, and 0.21 m, respectively, corresponding to sampling temperatures of 1492 Kelvin, 1484 Kelvin, 1448 Kelvin, and 1440 Kelvin. The temperature gradient amplitudes for the three sections are 800 Kelvin per m, 3600 Kelvin per m, and 800 Kelvin per m, respectively. Therefore, the spatial midpoint of the section between 0.19 m and 0.20 m, at 0.195 m, is recorded as the location of the first phase change interface.

[0144] The height coordinate of the set interface position corresponding to the first phase change interface position is 0.185 meters. The first phase change interface position extends 0.01 meters beyond the set interface position along the preset solidification growth direction, and the interface advance distance is 0.01 meters. The first heat pipe section to be adjusted only covers the interface advance distance position. Therefore, the candidate target heat flow direction is from the first heat pipe section to be adjusted towards the crucible sidewall.

[0145] The candidate target heat flow direction is consistent with the current heat flow direction, and the target heat flow direction is maintained from the first heat pipe section to be adjusted to the crucible sidewall.

[0146] The heat flux density correction ratio for the first heat pipe section to be adjusted is the ratio of 0.01 meters to 0.1 meters, i.e., 0.1; the heat flux density correction amount is 800 watts per square meter; the target heat flux density is 8800 watts per square meter.

[0147] The current heat flux density of the second heat pipe section to be adjusted is 6000 W / m², and the current heat flux direction is from the second heat pipe section to the crucible sidewall. The position of the second phase change interface lags behind the corresponding set interface position by 0.02 m along the preset solidification growth direction, with an interface lag distance of 0.02 m. The candidate target heat flux direction is from the crucible sidewall to the second heat pipe section to be adjusted. The candidate target heat flux direction is opposite to the current heat flux direction. The heat flux density correction ratio of the second heat pipe section to be adjusted is 0.2, and the heat flux density correction amount is 1200 W / m². After setting the original current heat flux density to zero, a target heat flux density of 1200 W / m² is formed along the target heat flux direction.

[0148] Based on the calibration relationship between the temperature setpoint of the temperature-controlled radiator and the actual heat flow direction, the temperature setpoint of the temperature-controlled radiator is adjusted to 420 Kelvin. After completing one control cycle, the working fluid inlet temperature of the first heat pipe section to be adjusted is 420 Kelvin, and the working fluid outlet temperature is 412 Kelvin, satisfying the target heat flow direction from the first heat pipe section to be adjusted towards the crucible sidewall; the working fluid inlet temperature of the second heat pipe section to be adjusted is 420 Kelvin, and the working fluid outlet temperature is 426 Kelvin, satisfying the target heat flow direction from the crucible sidewall towards the second heat pipe section to be adjusted.

[0149] The target working fluid inlet and outlet temperature difference for both heat pipe sections to be adjusted is taken as 8 Kelvin.

[0150] The target working fluid mass flow rate for the first heat pipe section to be adjusted is 0.022 kg / s; the target working fluid mass flow rate for the second heat pipe section to be adjusted is 0.003 kg / s.

[0151] The target working fluid mass flow rate is 0.025 kg / s, the working fluid flow rate ratio of the first heat pipe section to be adjusted is 0.88, and the working fluid flow rate ratio of the second heat pipe section to be adjusted is 0.12.

[0152] Based on the pre-established calibration relationship between the on / off duty cycle and the average working fluid mass flow rate, the initial on / off duty cycle of the first heat pipe section to be adjusted is set to 70%, and the initial on / off duty cycle of the second heat pipe section to be adjusted is set to 25%. After completing one control cycle, the measured average working fluid mass flow rates are 0.0213 kg / s and 0.0031 kg / s, respectively, with relative flow errors of 3.2% and 3.3%, respectively, both not exceeding the allowable flow error of 5%. Therefore, the current on / off duty cycles of the two electrically controlled throttle valves are maintained.

[0153] After completing one control cycle, the position of the first phase change interface is updated to 0.187 meters, with a directional deviation of 0.002 meters from the set interface position; the position of the second phase change interface is updated to 0.188 meters, with an absolute directional deviation of 0.002 meters from the corresponding set interface position. Since the absolute values ​​of both directional deviations are not greater than the allowable interface deviation, the generation of a new target heat flux density stops. The updated actual shape of the phase change interface, the target heat flux direction of the two heat pipe sections to be adjusted, the target heat flux density, the target working fluid mass flow rate, and the on / off duty cycle of the electronically controlled throttle valve are written into the same record, forming the dynamic control result of the phase change interface.

[0154] This embodiment also provides a computer device applicable to the dynamic control method of directional solidification phase change interface, including: a memory and a processor, a temperature acquisition interface, a flow acquisition interface, and a valve drive interface; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the dynamic control method of directional solidification phase change interface proposed in the above embodiment.

[0155] Temperature acquisition interfaces are connected to temperature probes at the inlet temperature measurement position, outlet temperature measurement position, and crucible temperature sampling position of each heat pipe section; flow acquisition interfaces are connected to mass flow meters of each heat pipe section; valve drive interfaces are connected to electrically controlled throttle valves of each heat pipe section.

[0156] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0157] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements the method for dynamic control of directional solidification phase change interfaces as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0158] In summary, this invention achieves directional correction and stable advancement of local deviations at the phase change interface by modifying the current heat flux density. It can suppress excessively rapid or slow local advancement of the solidification front, reduce reverse adjustment, heat mismatch, and reciprocating fluctuations of the interface, and gradually restore the solidification front to the expected morphology. It can maintain the coordination of axial temperature gradient and radial heat distribution, reduce the probability of interface protrusions, depressions, and continuous deviations, and enhance the response sensitivity and operational stability of the directional solidification process. At the same time, it can alleviate the thermal field distortion caused by local solidification rate differences, keep the solidification process in different spatial locations coordinated, reduce grain growth direction deviation and local microstructure inhomogeneity, improve the continuity of solidification structure, interface morphology consistency, and forming quality, and provide a reliable basis for the stable preparation of castings with complex cross-sections and long-dimensional materials.

[0159] 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 technical solutions 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 dynamic control of directional solidification phase change interface, characterized in that, include: The heat dissipation from solidification at the bottom of the crucible is transferred to the heat pipe section on the side wall of the crucible. The current heat flux density is calculated using the working fluid flow rate and the temperature difference between the inlet and outlet of the working fluid in each heat pipe section, and the current heat flux direction is assigned. The position of the phase change interface is located simultaneously, and the actual morphology of the phase change interface is obtained. By comparing the actual shape of the phase transition interface with the set shape of the phase transition interface, the interface lead distance and interface lag distance are obtained. The target heat flux direction required to reduce the interface lead distance and interface lag distance is determined by using the current heat flux direction. The current heat flux density is then corrected along the target heat flux direction to generate the target heat flux density. The target heat flux density is converted into a working fluid flow rate ratio, and the on / off duty cycle of the electronically controlled throttle valve is adjusted using the working fluid flow rate ratio. When the phase change interface exceeds the laying termination position of the current heat pipe section, the on / off duty cycle of the current electronically controlled throttle valve is maintained, and the adjustment of the adjacent heat pipe section is initiated to update the actual shape of the phase change interface until the interface lead distance and interface lag distance disappear, thus obtaining the dynamic control result of the phase change interface.

2. The method for dynamic control of directional solidification phase change interface as described in claim 1, characterized in that, The specific steps for calculating the current heat flux density are as follows: Based on the inlet and outlet temperature measurement positions of each heat pipe section, the working fluid inlet temperature and working fluid outlet temperature are obtained, and the temperature difference between the working fluid inlet temperature and the working fluid outlet temperature is determined as the working fluid inlet and outlet temperature difference. Within the temperature range covered by the temperature difference between the inlet and outlet of the working fluid, the flow rate of the working fluid and the temperature difference between the inlet and outlet of the working fluid are converted into the heat exchange per unit time of each heat pipe section by the isobaric specific heat capacity of the working fluid. The heat exchange rate per unit time is converted to area to obtain the current heat flux density.

3. The method for dynamic control of directional solidification phase change interface as described in claim 2, characterized in that, The process of assigning the current heat flow direction is as follows: for heat pipe sections where the working fluid inlet temperature is higher than the working fluid outlet temperature, the direction from the heat pipe section to the crucible sidewall is defined as the current heat flow direction; for heat pipe sections where the working fluid inlet temperature is lower than the working fluid outlet temperature, the direction from the crucible sidewall to the heat pipe section is assigned as the current heat flow direction. The location of the phase change interface is determined by arranging temperature sampling positions and sampling temperatures according to the preset solidification growth direction, selecting a temperature change section, and determining the phase change interface position based on the change ratio of the sampling temperatures at both ends of the selected temperature change section. The actual shape of the phase change interface is obtained by using the spatial coordinates of each phase change interface position in the crucible as the sorting reference, inserting interpolation positions between adjacent phase change interface positions, and merging the sorted phase change interface positions with the interpolation positions to obtain the actual shape of the phase change interface.

4. The method for dynamic control of directional solidification phase change interface as described in claim 3, characterized in that, The specific steps for obtaining the interface lead distance and interface lag distance are as follows: Read the pre-stored phase change interface setting pattern in the directional solidification process requirements, and select the setting interface position at the same spatial position as the crucible cross-section from the phase change interface setting pattern. Using the preset solidification growth direction as the criterion for determining the positional order, the phase change interface position is compared with the set interface position, and the distance by which the phase change interface position exceeds the set interface position along the preset solidification growth direction is recorded as the interface lead distance. The distance between the phase change interface position and the set interface position is recorded as the interface hysteresis distance.

5. The method for dynamic control of directional solidification phase change interface as described in claim 4, characterized in that, The specific steps for determining the target heat flow direction required to reduce the interface lead distance and interface lag distance using the current heat flow direction are as follows: Read the starting and ending positions of each heat pipe segment on the crucible sidewall, and select the heat pipe segment containing the positions of interface lead distance and interface lag distance as the heat pipe segment to be adjusted. In the heat pipe section to be adjusted, when only the interface leading distance position is covered, the direction from the heat pipe section to the crucible sidewall is determined as the candidate target heat flow direction; when only the interface lagging distance position is covered, the direction from the crucible sidewall to the heat pipe section is determined as the candidate target heat flow direction. When both interface lead distance and interface lag distance exist simultaneously, the direction of heat flow of the candidate target is determined by comparing the lengths of the interface lead distance and the interface lag distance. The candidate target heat flow direction is checked segment by segment against the current heat flow direction. When the directions are the same, the current heat flow direction is retained and used as the target heat flow direction. When the directions are opposite, the candidate target heat flow direction is used to replace the current heat flow direction to obtain the target heat flow direction.

6. The method for dynamic control of directional solidification phase change interface as described in claim 5, characterized in that, The specific steps for generating the target heat flux density are as follows: By utilizing the proportions of interface lead distance and interface lag distance in the laying length of the heat pipe section to be adjusted, the current heat flux density is converted into a heat flux density correction amount. The target heat flow direction is compared with the current heat flow direction. When the directions are the same, the current heat flow density of the heat pipe section to be adjusted is increased by the heat flow density correction amount. When the directions are opposite, the current heat flow density of the heat pipe section to be adjusted is reduced to zero, and the heat flow density correction amount is determined as the heat flow density of the heat pipe section to be adjusted along the target heat flow direction. The increased heat flux density and the reverse-determined heat flux density are used together as the target heat flux density.

7. The method for dynamic control of directional solidification phase change interface as described in claim 6, characterized in that, The working fluid flow rate ratio is calculated based on the target heat flux density, effective heat exchange area, average isobaric specific heat capacity, and working fluid inlet and outlet temperature difference of each heat pipe section to be adjusted, and the working fluid flow rate ratio is determined according to the proportion of each target working fluid flow rate in the total.

8. The method for dynamic control of directional solidification phase change interface as described in claim 7, characterized in that, The specific steps for initiating adjustment of adjacent heat pipe sections and updating the actual morphology of the phase change interface are as follows: When the phase change interface position crosses the termination position of the current heat pipe segment on the crucible sidewall, the adjacent heat pipe segment is activated. While keeping the on / off duty cycle of the electronically controlled throttle valve of the current heat pipe section constant, the on / off duty cycle of the electronically controlled throttle valve of the adjacent heat pipe section is adjusted by the ratio of the working fluid flow of the adjacent heat pipe section. The phase change interface position is repositioned at the sampling time after the adjacent heat pipe section is started, and the original phase change interface position is replaced with the repositioned phase change interface position, and the actual shape of the phase change interface is updated. The updated phase change interface actual form is compared with the phase change interface set form to obtain the interface lead distance and interface lag distance again. The target heat flux direction and target heat flux density are then regenerated using the newly obtained interface lead distance and interface lag distance until both interface lead distance and interface lag distance disappear.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the directional solidification phase change interface dynamic control method according to any one of claims 1-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for dynamic control of directional solidification phase change interface as described in any one of claims 1-8.

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