Performance evaluation method of aerogel felt applied to frozen soil heat insulation

Abstract

The invention discloses an aerogel felt performance evaluation method applied to frozen soil heat insulation, and relates to the technical field of frozen soil environment, and the method comprises the following steps: under a controlled one-dimensional heat transfer condition, determining corrected heat flux density acting on an aerogel felt sample; calculating to obtain equivalent thermal resistance of the aerogel felt sample in corresponding compaction and contact states; constructing a frozen soil interface temperature prediction model, and calculating to obtain a frozen soil temperature margin; constructing an equivalent heat flux model, and calculating a corresponding equivalent frozen soil interface temperature and an equivalent temperature margin; constructing a degradation thermal resistance model, correcting the equivalent thermal resistance to obtain degradation thermal resistance, and further calculating a thermal risk amplification coefficient; and calculating and constructing a normalized safety evaluation index based on the degradation temperature margin. According to the method, the engineering thermal load, the aerogel felt equivalent thermal resistance, the thermal load fluctuation conversion and the water-containing degradation effect are uniformly incorporated into the same evaluation chain, so that the conversion from a single material parameter to an engineering applicability index is realized.

Description

Technical Field

[0001] This invention relates to the field of permafrost environment technology, specifically to a method for evaluating the performance of aerogel felts used for permafrost insulation. Background Technology

[0002] In permafrost regions, the long-term safe operation of roads, utility tunnels, stations, and various infrastructures highly depends on the effective suppression of downward heat transfer by insulation structures. Aerogel felt, due to its low thermal conductivity, lightweight, and ease of construction, is gradually being introduced into permafrost insulation projects.

[0003] However, existing performance evaluation methods for aerogel felts are mostly derived from conventional thermal insulation material testing systems. The evaluation focus is usually on the static thermal conductivity or a single thermal resistance parameter under laboratory conditions, which is difficult to truly reflect the complex thermal boundary conditions that exist in frozen soil engineering.

[0004] On the one hand, existing technologies often ignore the impact of heat load fluctuations with the day and night and seasons, and the evaluation results are based on the assumption of constant temperature difference or constant heat flow, which makes it impossible to identify the insulation risk of materials under actual adverse working conditions in advance. On the other hand, aerogel blankets are inevitably subject to water migration and freeze-thaw cycles in permafrost environments. Existing assessment methods generally do not include the thermal resistance degradation caused by water content in a unified quantitative evaluation framework, which can easily overestimate the long-term thermal insulation capacity of the material, thus creating hidden dangers for the stability of permafrost. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for evaluating the performance of aerogel felts used for permafrost insulation, thereby resolving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for evaluating the performance of aerogel felts used for permafrost insulation, comprising the following steps: S1. Under controlled one-dimensional heat transfer conditions, apply a stable heat load to the aerogel felt sample to be tested and determine the corrected heat flux density acting on the aerogel felt sample. S2. Under the condition that the corrected heat flux density remains stable, the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states is calculated. S3. Based on the corrected heat flux density and the equivalent thermal resistance, construct a frozen soil interface temperature prediction model and calculate the frozen soil temperature margin. S4. Construct an equivalent heat flux model to obtain the equivalent heat flux with equivalent thermal effect, and calculate the corresponding equivalent frozen soil interface temperature and equivalent temperature margin. S5. Construct a degradation thermal resistance model, correct the equivalent thermal resistance to obtain a degradation thermal resistance that reflects the water content degradation effect, and further calculate the thermal risk amplification factor. S6. Calculate the predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions, and construct a normalized safety evaluation index based on the degradation temperature margin.

[0007] To further optimize this technical solution, in step S1, determining the corrected heat flux density acting on the aerogel felt sample includes: A one-dimensional dominant heat transfer clamping heat loading unit is constructed, with a constant power heating plate on the upper side, a constant temperature cooling plate on the lower side, and an aerogel felt sample sandwiched in the middle with the contact layers on both sides; lateral heat leakage is suppressed by a retaining ring / plate, so that the heat flow penetrates the sample thickness direction approximately perpendicularly. By converting the input power of heating to the effective heated area of ​​the sample, and combining it with edge heat dissipation correction, the corrected heat flux density acting on the aerogel felt sample is obtained.

[0008] To further optimize this technical solution, the calculation model for the corrected heat flux density is as follows: in, The electrical power on the heating side during the steady-state phase is expressed in units of... ; The effective heated area of ​​the sample, in units of ; This is the heat flux correction factor, which is dimensionless. To correct for heat flux density, the unit is... ; By employing traceable electrical power and effective heat transfer area, a corrected heat flux density is obtained to characterize the actual heat load transferred per unit area towards the frozen soil.

[0009] To further optimize this technical solution, in step S2, the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states is calculated, including: The surface temperatures of the hot and cold sides of the aerogel felt sample were measured separately to obtain the steady-state temperature difference across the sample. This steady-state temperature difference was then divided by the corrected heat flux density to calculate the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states. The calculation formula is as follows: in, The equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact conditions is given in units of 1. ; The steady-state temperature difference across the sample is expressed in units of 1. ; The equivalent thermal resistance obtained through calculation This is used to characterize the thermal insulation performance of aerogel felt under engineering constraints.

[0010] To further optimize this technical solution, the frozen soil interface temperature prediction model in step S3 is as follows: in, The equivalent temperature on the thermal side is the overlying structure / air-side driven temperature under the most unfavorable operating condition, in units of... ; The boundary equivalent thermal resistance is the combined heat transfer / paving layer impedance converted between the hot side of the aerogel felt and the environment, in units of... ; The upper limit of permafrost temperature, in units of ; To predict the permafrost interface temperature, the unit is... ; This refers to the temperature margin of frozen soil, in units of... ; when When, it indicates that the temperature of the frozen soil interface is below the upper limit under this working condition, and the insulation meets the requirements; when When this occurs, it indicates a risk of crossing the boundary.

[0011] To further optimize this technical solution, in step S4, the heat flux that changes with time is converted within a predetermined evaluation time window. An equivalent heat flux equivalent to the thermal effect within the time window is obtained through an equivalent heat flux model. Under the condition of keeping the equivalent thermal resistance and the boundary equivalent thermal resistance unchanged, the corresponding equivalent frozen soil interface temperature and equivalent temperature margin are calculated to characterize the thermal insulation performance of aerogel felt under fluctuating heat load conditions.

[0012] To further optimize this technical solution, the equivalent heat flux model is as follows: in, This represents the corrected heat flux density as a function of time within the evaluation window, in units of... ; To evaluate window length, the unit is... ; Equivalent heat flux, unit: ; Subsequently, the equivalent frozen soil interface temperature was obtained using the model from step S3. With equivalent temperature margin .

[0013] To further optimize this technical solution, in step S5, the degradation thermal resistance model is as follows: in, Moisture content; The water content influence coefficient is used to characterize the sensitivity of aerogel felt to thermal resistance due to water content in this structural system. Degradation thermal resistance, unit: ; The model corrects the thermal resistance from the dry baseline to the degraded thermal resistance using measurable water content parameters.

[0014] To further optimize this technical solution, in step S5, the thermal risk amplification factor is used to describe the equivalent heat flux. The amplification effect of the decrease in thermal resistance caused by water content on the interface temperature is calculated as follows: in, This is the thermal risk amplification factor; When water content leads to As the denominator decreases, the denominator also decreases, thus... This indicates that the risk of heat has been amplified; if If the set threshold is exceeded, even if the dry margin is sufficient, it may fail in the wet state.

[0015] To further optimize this technical solution, in step S6, the predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions are calculated using the model in step S3, and the normalized safety evaluation index is determined based on the ratio of the degradation temperature margin to the upper limit temperature of the frozen soil.

[0016] 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 instructions are executed by the processor, they implement the steps of a method for evaluating the performance of aerogel felt applied to permafrost insulation as described in the first aspect of the present invention.

[0017] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program instructions are executed by a processor, they implement the steps of a method for evaluating the performance of aerogel felt applied to permafrost insulation as described in the first aspect of the present invention.

[0018] Compared with the prior art, the present invention provides a method for evaluating the performance of aerogel felts used for permafrost insulation, which has the following beneficial effects: This performance evaluation method for aerogel felts applied to permafrost insulation integrates engineering heat load, equivalent thermal resistance of aerogel felts, heat load fluctuation conversion, and water content degradation effects into a single evaluation chain. This transforms the evaluation from a single material parameter to an "engineering suitability" index. It can not only quantitatively provide the temperature margin of aerogel felts under the most unfavorable heat load and water content conditions in permafrost, but also intuitively reflect the level of thermal insulation reliability through normalized safety indicators. This provides a more realistic, forward-looking, and engineering-guiding technical basis for the selection, thickness design, and long-term safety assessment of aerogel felts in permafrost engineering. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0020] Figure 1 This is a schematic flowchart of a method for evaluating the performance of aerogel felt applied to permafrost insulation, as proposed in this invention. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] Secondly, the term "an 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 throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0024] Example 1: Reference Figure 1 This is the first embodiment of the present invention, which provides a method for evaluating the performance of aerogel felt applied to permafrost insulation, including the following steps: S1. Under controlled one-dimensional heat transfer conditions, apply a stable heat load to the aerogel felt sample to be tested and determine the corrected heat flux density acting on the aerogel felt sample.

[0025] In permafrost insulation scenarios, the quality of aerogel felt cannot be judged solely by the thermal conductivity of the material itself. Instead, its ability to suppress heat transfer to permafrost must be evaluated under thermal boundaries close to engineering constraints.

[0026] Determining the corrected heat flux density acting on the aerogel felt sample includes: A one-dimensional dominant heat transfer clamping heat loading unit was constructed, with a constant power heating plate on the upper side and a constant temperature cold plate (simulating a frozen soil cold source) on the lower side, and the aerogel felt sample and the contact layers on both sides were clamped in the middle; the lateral heat leakage was suppressed by the protective ring / plate, so that the heat flow penetrated the sample thickness direction approximately perpendicularly. By converting the input power of heating to the effective heated area of ​​the sample, and combining it with edge heat dissipation correction, the corrected heat flux density acting on the aerogel felt sample is obtained.

[0027] The calculation model for the corrected heat flux density is shown below: in, The electrical power on the heating side during the steady-state phase is expressed in units of... The method of acquisition is as follows: connect a power meter or electrical parameter acquisition module in series in the heater power supply circuit to directly read the steady-state average power (a 60s moving average can be used to suppress ripple).

[0028] The effective heated area of ​​the sample, in units of The method of obtaining this information is as follows: measure according to the geometric dimensions of the clamping window and deduct the area covered by the chamfer / edge pressing.

[0029] This is a dimensionless heat flux correction coefficient used to convert unavoidable non-ideal factors such as edge heat dissipation and contact layer bypass heat conduction back to the one-dimensional dominant conditions. It is obtained by using a standard plate with known in-plane uniform thermal conductivity, controllable thickness, and traceable thermal conductivity for calibration under the same clamping conditions. The coefficient is then calculated by back-calculating the theoretical one-dimensional heat flux / measured power density. (Can be reused under the same clamping structure, the same clamping force and the same retaining ring conditions).

[0030] To correct for heat flux density, the unit is... .

[0031] By employing traceable electrical power and effective heat transfer area, a corrected heat flux density is obtained to characterize the actual heat load transferred per unit area towards the frozen soil.

[0032] S2. Under the condition that the corrected heat flux density remains stable, the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states is calculated.

[0033] When aerogel blankets are used for insulation in permafrost, their engineering value lies in "how much temperature drop they can generate under a given heat load," which is essentially determined by the equivalent thermal resistance. Unlike measuring only thermal conductivity, equivalent thermal resistance... This approach unifies the combined effects of material pore structure, compaction state, interfacial contact, and potential radiation / microconvection suppression into a single quantity suitable for engineering calculations. This step uses the corrected heat flux density output from S1. To ensure the sole heat input, a mechanism for measuring the temperature difference across the felt and calculating the thermal resistance is established: a set of thin thermocouples or high-precision temperature gauges are arranged on the upper and lower surfaces of the sample, and the measurement error is reduced by using a thin, highly thermally conductive temperature equalization plate (such as a metal foil); at the same time, the clamping force is kept constant so that the thickness change caused by compression becomes "part of the real working condition" rather than being artificially eliminated.

[0034] Calculate the equivalent thermal resistance of the aerogel felt specimen under corresponding compaction and contact conditions, including: The surface temperatures of the hot and cold sides of the aerogel felt sample were measured separately to obtain the steady-state temperature difference across the sample. This steady-state temperature difference was then divided by the corrected heat flux density to calculate the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states. The calculation formula is as follows: in, The equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact conditions is given in units of 1. .

[0035] The steady-state temperature difference across the sample is expressed in units of 1. The method of acquisition is as follows: read the surface temperature of the hot side of the sample during the steady-state stage. With cold side surface temperature and calculate .here and Sensors using the same calibration system and recording data in the same data acquisition channel are employed to reduce system bias; steady-state criteria are directly based on the rate of temperature change (e.g., and Simultaneously, the average time window is determined based on the power level (which is less than the threshold), ensuring consistency with the steady-state power window in step S1, thereby enabling... and They correspond to the same physical state.

[0036] The equivalent thermal resistance obtained through calculation This is used to characterize the thermal insulation performance of aerogel felt under engineering constraints.

[0037] S3. Based on the corrected heat flux density and the equivalent thermal resistance, construct a frozen soil interface temperature prediction model, calculate and predict the frozen soil interface temperature, and further obtain the frozen soil temperature margin to determine the thermal insulation safety of aerogel felt for frozen soil under a single stable heat load.

[0038] The core of permafrost insulation is not "large temperature drop of the material", but "temperature at key locations on the permafrost side does not exceed the limit". Therefore, this step introduces the permafrost temperature margin. It indicates how much "safety margin" the aerogel felt leaves between the permafrost side interface temperature and the upper limit of the allowable range under given heat load and boundary thermal resistance conditions.

[0039] The frozen soil interface temperature prediction model is shown below: in, The equivalent temperature on the thermal side is the overlying structure / air-side driven temperature under the most unfavorable operating condition, in units of... The acquisition method is as follows: in engineering application scenarios, use a temperature recorder to sample during a typical hot season and obtain the design quantile value (e.g., the statistical quantile of the daily maximum temperature), or directly set it using a constant temperature plate in the laboratory.

[0040] The boundary equivalent thermal resistance is the combined heat transfer / paving layer impedance converted between the hot side of the aerogel felt and the environment, in units of... The method of obtaining the value is as follows: without placing aerogel felt, the "boundary layer only" is calibrated and back-calculated using the same clamping structure, or it is obtained by converting the heat transfer coefficient under controlled convection conditions.

[0041] The upper limit of permafrost temperature, in units of It is given by the permafrost stability requirements (e.g., constrained by the fact that the frozen interface does not melt or the strength of the ice-containing soil does not decrease significantly).

[0042] To predict the permafrost interface temperature, the unit is... .

[0043] This refers to the temperature margin of frozen soil, in units of... .

[0044] when When, it indicates that the temperature of the frozen soil interface is below the upper limit under this working condition, and the insulation meets the requirements; when When this occurs, it indicates a risk of crossing the boundary.

[0045] S4. Considering the characteristics of heat load variation over time in frozen soil insulation conditions, an equivalent heat flux model is constructed to obtain the equivalent heat flux with equivalent thermal effect, and the corresponding equivalent frozen soil interface temperature and equivalent temperature margin are calculated.

[0046] The key challenge in permafrost insulation scenarios lies in the fact that the heat load is not constant, and the equivalent temperature on the thermal side... The heat exchange with the outside environment fluctuates with changes in day and night, season, and soil moisture content. If only the single-condition margin of step S3 is used... Evaluations can easily result in situations where "the test results are satisfactory, but the actual performance in engineering tests is unsatisfactory at certain times." Therefore, this step proposes an equivalent heat load conversion method: converting the heat flux sequence within an evaluation window (e.g., several consecutive days in a hot season, or the most unfavorable month of the design year) into an equivalent heat flux. This makes the equivalent thermal resistance of the same material Equivalent thermal resistance at the boundary Under these conditions, the temperature at the permafrost side interface reaches the same "thermal driving effect," thus obtaining an equivalent temperature margin. .

[0047] Within a predetermined evaluation time window, the heat flux that changes over time is converted, and the equivalent heat flux equivalent to the thermal effect within that time window is obtained through the equivalent heat flux model. Under the condition that the equivalent thermal resistance and the boundary equivalent thermal resistance remain unchanged, the corresponding equivalent frozen soil interface temperature and equivalent temperature margin are calculated to characterize the thermal insulation performance of aerogel felt under fluctuating heat load conditions.

[0048] The equivalent heat flux model is shown below: in, This represents the corrected heat flux density as a function of time within the evaluation window, in units of... The method of obtaining the data is as follows: A heat flow meter can be installed on the hot side of the insulation layer on-site, or the data can be obtained by comparing the "power / area" value with the correction coefficient. The conversion method is used; in the laboratory, different temperatures / power can be applied at different times through programmed temperature / power control. And obtain the corresponding method according to step S1. .

[0049] To evaluate window length, the unit is... The method of obtaining this value is: set according to the engineering evaluation cycle and converted to seconds.

[0050] Equivalent heat flux, unit: .

[0051] Subsequently, the equivalent frozen soil interface temperature was obtained using the model from step S3. With equivalent temperature margin : Here The unfavorable equivalent temperature of the design within the evaluation window (e.g., the upper quantile value within the window) can be obtained in the same way as in S3. This step uses... As a criterion for "maintaining the safety of permafrost under fluctuating heat loads," and because... from The calculation retains the peak contribution; when When the value is close to 0 or negative, it indicates that the degradation of material properties under conditions of water content and freeze-thaw cycles needs to be considered.

[0052] S5. Based on the equivalent heat flux as the heat-driven input, the water content of the aerogel felt is introduced. By combining the water content with the predetermined water content influence coefficient, a degradation thermal resistance model is constructed to correct the equivalent thermal resistance, thereby obtaining the degradation thermal resistance that reflects the water content degradation effect. Furthermore, the thermal risk amplification factor is calculated to characterize the amplification effect of heat load on the frozen soil interface temperature under water content conditions.

[0053] In permafrost regions, aerogel mats are subjected to prolonged wet migration and freeze-thaw cycles. Moisture content significantly increases the effective heat conduction path (liquid water has higher thermal conductivity than the gas phase) and may cause structural changes in the fiber substrate or hydrophobic system. If the effect of moisture content is not included in the performance evaluation, relying solely on the equivalent resistivity in the dry state will lead to problems. margin or The safety of thermal insulation may be overestimated.

[0054] The degradation thermal resistance model is shown below: in, Moisture content; obtained by weighing the wet mass of samples from the same batch after specified water absorption / freeze-thaw pretreatment. With drying quality and calculate This acquisition method belongs to state representation, and its purpose is clearly aimed at thermal resistance degradation modeling.

[0055] The water content influence coefficient is used to characterize the sensitivity of aerogel felt to thermal resistance in this structural system; it is obtained by selecting at least two to three different... For horizontal samples, the corresponding thermal resistance is measured according to steps S1-S2. Values ​​and regressions are obtained The same product system can form fixed parameters.

[0056] Degradation thermal resistance, unit: ; This model corrects the thermal resistance from the dry baseline to the degraded thermal resistance using measurable moisture content indicators. The higher the moisture content, the more significant the decrease in equivalent thermal resistance; when... hour, This is consistent with the dry state.

[0057] The thermal risk amplification factor is used to describe the effect of equivalent heat flux. The amplification effect of the decrease in thermal resistance caused by water content on the interface temperature is calculated as follows: in, This is the thermal risk amplification factor; When water content leads to As the denominator decreases, the denominator also decreases, thus... This indicates that the risk of heat has been amplified; if If the set threshold is exceeded, even if the dry margin is sufficient, it may fail in the wet state.

[0058] S6. Calculate the predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions, and construct a normalized safety evaluation index based on the degradation temperature margin, so as to determine and classify the comprehensive thermal insulation performance of aerogel felt in frozen soil thermal insulation application.

[0059] The ultimate goal of completing the evaluation of the thermal insulation performance of frozen soil is to provide a conclusion on whether it is still safe under the most unfavorable heat load and the most unfavorable water content conditions, as well as a classification index to facilitate engineering selection.

[0060] The predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions are calculated using the model in step S3. The normalized safety evaluation index is determined based on the ratio of degradation temperature margin to the upper limit temperature of frozen soil.

[0061] Specifically, the predicted frozen soil interface temperature is calculated under the most unfavorable water content and heat load conditions. With degradation temperature margin : Next, to establish clear performance levels, a normalized safety index is defined. : when and When the value exceeds the set lower limit, it can be determined that the aerogel felt still meets the insulation requirements of frozen soil under the combined unfavorable conditions of "heat load fluctuation + water content degradation"; when If the boundary is breached, it is determined that there is a risk of permafrost crossing the boundary. Therefore, it is necessary to increase the thermal resistance of materials (e.g., by thickening or using higher-grade products), reduce the boundary heat load (by improving the cover / reflective layer), or adopt a waterproof and vapor-barrier structure to reduce the risk. .

[0062] To ensure project implementation, a tiered rule example can be provided: If Significantly greater than 0 and A value close to 1 indicates that the material is not sensitive to moisture content and has a weak thermal risk amplification, thus it can be classified as a high reliability level; if... Positive but close to 0 or If the value is relatively large, it is considered a critical level, and it is recommended to increase the design margin; if This indicates that the required level is not met.

[0063] Example 2: Based on the method in Example 1, this method can be practically applied to the selection and safety assessment of insulation structures along oil and gas pipelines in permafrost regions. Taking buried oil pipelines in high-altitude and cold regions as an example, the pipeline continuously releases heat to the surrounding soil during operation, and the heat load transferred to the permafrost layer exhibits significant time-varying characteristics due to seasonal changes, temperature fluctuations of the transported medium, and surface radiation conditions. Simultaneously, the pipeline backfill area and insulation layer are constantly exposed to groundwater seepage and freeze-thaw cycles, inevitably causing a certain degree of moisture content and performance degradation in the aerogel felt.

[0064] In this scenario, the proposed aerogel felt sample can be incorporated into this method for performance evaluation during the engineering design phase. First, the most unfavorable operating heat load of the pipeline is simulated under laboratory conditions to obtain the equivalent thermal resistance of the aerogel felt. Then, the heat load fluctuations within a typical operating cycle are converted into equivalent heat flux, and combined with a degradation thermal resistance model under water-bearing conditions, the temperature margin and safety evaluation indicators of the permafrost interface are calculated. Based on this evaluation result, engineers can determine whether the pipeline insulation structure can still prevent permafrost thawing under the most unfavorable operating and environmental conditions, and optimize the thickness configuration of the aerogel felt or the waterproofing structure accordingly. This effectively reduces engineering risks such as permafrost settlement and pipeline instability, and improves the long-term operational safety of pipeline projects in permafrost areas.

[0065] Example 3: This embodiment also provides a computer device applicable to a method for evaluating the performance of aerogel felt for permafrost insulation, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method for evaluating the performance of aerogel felt for permafrost insulation as proposed in the above embodiment.

[0066] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for evaluating the performance of aerogel felts applied to permafrost insulation as proposed in the above embodiments.

[0067] 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.

[0068] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0069] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0070] More specific examples (a non-exhaustive list) of computer-readable media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0071] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0072] 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 evaluating the performance of aerogel blanket for insulating frozen ground, characterized by, Includes the following steps: S1. Under controlled one-dimensional heat transfer conditions, apply a stable heat load to the aerogel felt sample to be tested and determine the corrected heat flux density acting on the aerogel felt sample. S2. Under the condition that the corrected heat flux density remains stable, the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states is calculated. S3. Based on the corrected heat flux density and the equivalent thermal resistance, construct a frozen soil interface temperature prediction model and calculate the frozen soil temperature margin. S4. Construct an equivalent heat flux model to obtain the equivalent heat flux with equivalent thermal effect, and calculate the corresponding equivalent frozen soil interface temperature and equivalent temperature margin. S5. Construct a degradation thermal resistance model, correct the equivalent thermal resistance to obtain a degradation thermal resistance that reflects the water content degradation effect, and further calculate the thermal risk amplification factor. S6. Calculate the predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions, and construct a normalized safety evaluation index based on the degradation temperature margin.

2. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S1, determining the corrected heat flux density acting on the aerogel felt sample includes: A one-dimensional dominant heat transfer clamping heat loading unit is constructed, with a constant power heating plate on the upper side, a constant temperature cooling plate on the lower side, and an aerogel felt sample sandwiched in the middle with the contact layers on both sides; lateral heat leakage is suppressed by a retaining ring / plate, so that the heat flow penetrates the sample thickness direction approximately perpendicularly. By converting the input power of heating to the effective heated area of ​​the sample, and combining it with edge heat dissipation correction, the corrected heat flux density acting on the aerogel felt sample is obtained.

3. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 2, characterized in that, The calculation model for the corrected heat flux density is shown below: in, The electrical power on the heating side during the steady-state phase is expressed in units of... ; The effective heated area of ​​the sample, in units of ; This is the heat flux correction factor, which is dimensionless. To correct for heat flux density, the unit is... ; By employing traceable electrical power and effective heat transfer area, a corrected heat flux density is obtained to characterize the actual heat load transferred per unit area towards the frozen soil.

4. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S2, the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states is calculated, including: The surface temperatures of the hot and cold sides of the aerogel felt sample were measured separately to obtain the steady-state temperature difference across the sample. This steady-state temperature difference was then divided by the corrected heat flux density to calculate the equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact states. The calculation formula is as follows: in, The equivalent thermal resistance of the aerogel felt sample under the corresponding compaction and contact conditions is given in units of 1. ; The steady-state temperature difference across the sample is expressed in units of 1. ; The equivalent thermal resistance obtained through calculation This is used to characterize the thermal insulation performance of aerogel felt under engineering constraints.

5. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S3, the frozen soil interface temperature prediction model is as follows: in, The equivalent temperature on the thermal side is the overlying structure / air-side driven temperature under the most unfavorable operating condition, in units of... ; The boundary equivalent thermal resistance is the combined heat transfer / paving layer impedance converted between the hot side of the aerogel felt and the environment, in units of... ; The upper limit of permafrost temperature, in units of ; To predict the permafrost interface temperature, the unit is... ; This refers to the temperature margin of frozen soil, in units of... ; when When, it indicates that the temperature of the frozen soil interface is below the upper limit under this working condition, and the insulation meets the requirements; when When this occurs, it indicates a risk of crossing the boundary.

6. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S4, the heat flux that changes with time is converted within a predetermined evaluation time window. An equivalent heat flux equivalent to the thermal effect within the time window is obtained through an equivalent heat flux model. Under the condition that the equivalent thermal resistance and the boundary equivalent thermal resistance remain unchanged, the corresponding equivalent frozen soil interface temperature and equivalent temperature margin are calculated to characterize the thermal insulation performance of aerogel felt under fluctuating heat load conditions.

7. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 6, characterized in that, The equivalent heat flux model is shown below: in, This represents the corrected heat flux density as a function of time within the evaluation window, in units of... ; To evaluate window length, the unit is... ; Equivalent heat flux, unit: ; Subsequently, the equivalent frozen soil interface temperature was obtained using the model from step S3. With equivalent temperature margin .

8. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S5, the degradation thermal resistance model is as follows: in, Moisture content; The water content influence coefficient is used to characterize the sensitivity of aerogel felt to thermal resistance due to water content in this structural system. Degradation thermal resistance, unit: ; The model corrects the thermal resistance from the dry baseline to the degraded thermal resistance using measurable water content parameters.

9. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S5, the thermal risk amplification factor is used to describe the equivalent heat flux. The amplification effect of the decrease in thermal resistance caused by water content on the interface temperature is calculated as follows: in, This is the thermal risk amplification factor; When water content leads to As the denominator decreases, the denominator also decreases, thus... This indicates that the risk of heat has been amplified; if If the set threshold is exceeded, even if the dry margin is sufficient, it may fail in the wet state.

10. The method for evaluating the performance of aerogel felt applied to permafrost insulation according to claim 1, characterized in that, In step S6, the predicted frozen soil interface temperature and degradation temperature margin under the most unfavorable water content and heat load conditions are calculated using the model in step S3, and the normalized safety evaluation index is determined based on the ratio of degradation temperature margin to the upper limit temperature of frozen soil.

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