A method for constructing a temperature-humidity equivalent relationship based on a Mollier diagram

Abstract

A kind of Mollier chart-based temperature and humidity equivalent relationship construction method, comprising the following steps: collecting the environmental data of target area, correcting the air temperature and relative humidity on metal surface state, obtaining the metal surface temperature and metal surface relative humidity corresponding to metal corrosion interface, using metal surface temperature and metal surface relative humidity as Mollier chart calculation input, establishing target area Mollier chart enthalpy database, point-by-point judging rainfall information, condensation information and metal surface relative humidity corresponding to multiple sampling times, then respectively accumulating statistics on the wet air enthalpy in multiple state sets, obtaining total annual enthalpy, and determining effective corrosion enthalpy, using pollutant acceleration coefficient to correct, determining the temperature and humidity equivalent relationship between natural environment and indoor equivalent environment, with the advantages of clear equivalent basis, strong regional adaptability, quantifiable test parameters, high corrosion correlation and compressible evaluation period.

Description

Technical Field

[0001] This invention belongs to the field of material environmental adaptability and environmental corrosion evaluation technology, specifically involving a method for constructing the equivalent relationship of temperature and humidity based on Mollier diagrams. Background Technology

[0002] In recent years, metal substrates, coating materials, and plating materials have been widely used in marine engineering, rail transportation, energy equipment, outdoor facilities, and industrial atmospheric environments. During their service, they are easily affected by factors such as temperature, relative humidity, rainfall, condensation, chloride ion deposition, sulfur dioxide pollution, and acid precipitation. These environmental factors do not act alone, but rather form a continuous process of temperature and humidity changes and pollutant deposition processes with diurnal, seasonal, and regional variations. This makes the corrosion behavior of material surfaces exhibit obvious regionality, cumulativeity, and coupling. Current environmental corrosion assessment of metal materials usually adopts natural exposure tests, salt spray tests, damp heat tests, wet-dry alternation tests, or combinations thereof. While natural exposure tests can more realistically reflect the corrosion failure process of materials in actual service environments, the test cycle is long and highly dependent on the region. It usually takes many years to obtain stable conclusions, which is not conducive to the rapid screening and engineering evaluation of new materials, new coatings, and new protective structures. Therefore, further optimization is needed.

[0003] To shorten the evaluation cycle, existing technologies typically transform natural service environments into indoor accelerated testing conditions, using salt spray, damp heat, drying, or alternating wet and dry modules to accelerate material evaluation. These indoor accelerated tests often use single temperature, humidity, salt spray concentration, drying time, and damp heat time as optimization conditions, and determine the test cycle through empirical acceleration factors or preset cycle regimes. Simultaneously, some current technologies also employ schemes that compile environmental profiles based on actual service environment data. For example, environmental profiles are determined based on temperature, humidity, salt spray data, sulfur dioxide data, and rainfall pH information. Then, based on the equivalence principles of temperature and humidity and the equivalence principles of pollutant corrosion, calculations are performed for damp heat modules, salt spray concentration, and damp heat. While dynamic environmental spectra for fog and drying modules are available, these solutions typically focus on combinations of environmental spectra for specific products, operating cycles, or application scenarios. They are easily limited by object type, operating path, and empirical module division methods. For complex environments such as coastal high-salt and high-humidity environments, industrial atmospheric sulfur pollution, and frequent alternations of rainfall and condensation, relying solely on conventional meteorological data, fixed module parameters, or empirical acceleration relationships is insufficient to accurately characterize the temperature and humidity state of the actual corrosion interface on the material surface. Furthermore, it is difficult to uniformly convert the dry, humid, and wet states throughout the year into calculable and comparable equivalent relationships, thus failing to meet current requirements.

[0004] There is an urgent need for a method to construct the equivalent relationship of temperature and humidity based on Mollier diagrams, in order to solve the problems in existing accelerated corrosion tests, such as unclear equivalent basis of temperature and humidity, insufficient correspondence of material surface state, limited regional mapping ability, and difficulty in quantitatively converting the coupling effect of multiple factors. Summary of the Invention

[0005] This invention uses the enthalpy of moist air as an intermediate equivalent between the natural environment and the indoor equivalent environment. It corrects the air temperature and relative humidity of the target area for the metal surface temperature and relative humidity. Based on the corrected temperature and humidity data, it establishes a Mollier enthalpy database for the target area. This solves the technical problems in existing accelerated corrosion tests, such as unclear temperature and humidity equivalence, insufficient correspondence of material surface conditions, limited regional mapping ability, and difficulty in quantitatively converting the coupling effects of multiple factors.

[0006] To achieve the above-mentioned technical objectives, the specific technical solution adopted by the present invention is as follows: A method for constructing the isoequivalence relationship of temperature and humidity based on Mollier plots includes the following steps: S1. Collect environmental data of the target area, including air temperature, relative humidity, rainfall information, condensation information, chloride ion deposition rate and sulfur dioxide pollution level; S2. Correct the air temperature and relative humidity for metal surface condition to obtain the metal surface temperature and metal surface relative humidity corresponding to the metal corrosion interface; S3. Using metal surface temperature and relative humidity as inputs for Mollier plot calculation, calculate the enthalpy of moist air at each sampling time based on the relationship between enthalpy and moist air. Store the metal surface temperature, relative humidity and enthalpy of moist air at each sampling time in chronological order to form a sequence of enthalpy of moist air throughout the year for the target area. Establish a Mollier plot enthalpy database for the target area based on the sequence of enthalpy of moist air throughout the year for the target area. S4. Based on the Mollier map enthalpy database of the target area, the rainfall information, condensation information and relative humidity of the metal surface corresponding to multiple sampling times are determined point by point. The annual environmental process is divided into dry state, humid air state and wet state. The sampling times belonging to the dry state are assigned to the dry state set, the sampling times belonging to the humid air state set are assigned to the humid air state set, and the sampling times belonging to the wet state set are assigned to the wet state set. The enthalpy values ​​of the humid air in the above state sets are accumulated and statistically analyzed to obtain the segmented enthalpy contribution of the dry state, the segmented enthalpy contribution of the humid air state, and the segmented enthalpy contribution of the wet state. S5. The enthalpy contributions of the dry state segment, the enthalpy contributions of the humid air state segment, and the enthalpy contributions of the wetted state segment are summed to obtain the total enthalpy value for the whole year. The enthalpy contribution of the humid air state segment is used as the enthalpy value sensitive to humid air corrosion. The enthalpy contribution of the wetted state segment is converted to wettability and used as the enthalpy value sensitive to wetting corrosion. The effective corrosion enthalpy value is determined based on the enthalpy value sensitive to humid air corrosion and the enthalpy value sensitive to wetting corrosion. S6. Determine the pollutant acceleration coefficient based on the chloride ion deposition rate, sulfur dioxide pollution level, and electrochemical test results. Use the pollutant acceleration coefficient to correct the amount of pollutant corrosion acceleration in the indoor equivalent environment. Then, based on the total annual enthalpy, effective corrosion enthalpy, and the indoor equivalent environment corrected by the pollutant acceleration coefficient, determine the temperature and humidity equivalence relationship between the natural environment and the indoor equivalent environment.

[0007] Furthermore, in step S4, when the rainfall information indicates no rainfall, the condensation information indicates no condensation, and the relative humidity of the metal surface is less than 70%, the corresponding sampling time is determined to be a dry state; when the rainfall information indicates no rainfall, the condensation information indicates no condensation, and the relative humidity of the metal surface is greater than or equal to 70% and less than 100%, the corresponding sampling time is determined to be a humid air state; when at least one of the following is true: rainfall information indicates rainfall, condensation information indicates condensation, and the relative humidity of the metal surface reaches 100%, the corresponding sampling time is determined to be a wet state.

[0008] Furthermore, in step S3, the enthalpy value of the moist air is calculated according to the following formula: H =C pg · T +(Q g +C pq · T )· d / 1000; Where H is the enthalpy of a unit mass of moist air, T is the metal surface temperature, Cpg is the specific heat at constant pressure of dry air, Cpq is the specific heat at constant pressure of water vapor, Qg is the latent heat of vaporization of water at 0℃, and d is the absolute humidity.

[0009] Furthermore, the absolute humidity d is calculated using the following formula: d =621.9· φ ·P vs ( T ) / ( P - φ ·P vs ( T )); Among them, among them, φ P represents the relative humidity of the metal surface. vs (T ) represents the surface temperature of the metal. T The partial pressure of saturated water vapor under the given conditions, where P is the calculated pressure parameter.

[0010] Furthermore, in step S2, the air temperature is segmented and corrected according to the time range of the sampling time to obtain the metal surface temperature, and the relative humidity is converted according to the saturated water vapor partial pressure corresponding to the metal surface temperature to obtain the relative humidity of the metal surface.

[0011] Furthermore, in step S5, the wetting conversion is to convert the contribution of the segmented enthalpy value of the wetting state according to a weight of 1 / 4.2, and the effective corrosion enthalpy value is the sum of the enthalpy value of corrosion sensitivity of humid air and the converted wetting corrosion sensitivity enthalpy value.

[0012] Furthermore, in step S6, the concentration range of sodium sulfate (Na2SO4) in the indoor equivalent environment is determined based on the classification results of sulfur dioxide pollution levels, and the concentration range of sodium chloride (NaCl) in the indoor equivalent environment is determined based on the classification results of chloride ion deposition rates. A test concentration is then selected within the concentration ranges of sodium sulfate (Na2SO4) and sodium chloride (NaCl) to form a target test solution for determining the pollutant acceleration coefficient.

[0013] Furthermore, the pollutant acceleration coefficient K in step S6 p The corrosion current density ratio, K, is determined by measuring the potentiodynamic polarization curve. p = i corr,s / i corr,0 ;in, i corr,s The corrosion current density in the target test solution, i corr,0 This represents the corrosion current density in deionized water.

[0014] Furthermore, in step S6, the temperature of the damp heat test and the salt spray test is set according to the annual average metal surface temperature of the target area plus 20 to 25°C, and the test temperature is not lower than 25°C. The relative humidity of the damp heat test is set according to the annual average relative humidity of the metal surface plus 20%, and is controlled within the range of 70% to 95%. The relative humidity of the drying test is set to 30%, and the relative humidity of the salt spray test is calculated as 100%.

[0015] Furthermore, the 24-hour cycle test process in step S6 consists of salt spray test, drying test, damp heat test and drying test in sequence. The time ratio of each test module is determined according to the enthalpy ratio corresponding to the dry state, humid air state and wetted state. The equivalent energy Eday for a 24-hour cycle is calculated as follows: Eday =4.2·K p ·H ss ·t ss +H dry ·t dry +H wh ·t wh; Among them, H ss H dry and H wh These are the base enthalpy values ​​for the salt spray, drying, and damp heat modules, respectively, t. ss t dry and t wh These represent the duration of the corresponding module; Target acceleration test days N according to E target / E day Confirmed, of which E target This refers to the total enthalpy value or effective corrosion enthalpy value for the whole year.

[0016] This invention uses the enthalpy of moist air as a unified equivalent parameter to convert the temperature and humidity changes, moisture state, and corrosive effects of pollutants in the natural environment into an accumulative and calculable environmental effect. This establishes a continuous correspondence between the natural environment and the equivalent indoor environment. It does not simply superimpose enthalpy-humidity charts, salt spray tests, damp heat tests, and electrochemical tests, but rather connects each step around the same equivalent logic of temperature and humidity, avoiding the problem of relying solely on empirical multiples and isolated environmental parameters to determine accelerated test conditions.

[0017] By adopting the above technical solution, the present invention can also bring the following beneficial effects: 1. This invention proposes a method for constructing the equivalent relationship between temperature and humidity based on Mollier diagrams. It uses the enthalpy of moist air as the core equivalent parameter between the natural environment and the indoor equivalent environment, transforming the combined effects of temperature and humidity on the corrosive environment into calculable, cumulative, and comparable enthalpy data. This avoids the problem of excessive reliance on empirical multiples and fixed cycle parameters in existing accelerated corrosion tests, and enables the setting of the indoor equivalent environment to be based on the actual environmental data of the target area. It has the advantages of clear equivalent basis, quantifiable calculation process, and stable environmental mapping relationship.

[0018] 2. This invention proposes a method for constructing the temperature and humidity equivalence relationship based on Mollier diagrams. When constructing the temperature and humidity equivalence relationship, factors such as rainfall information, condensation information, chloride ion deposition rate, and sulfur dioxide pollution level are incorporated into the same evaluation system. Furthermore, the environmental processes throughout the year are distinguished by combining dry, humid, and wet conditions. This allows the corrosion sensitivity under different environmental conditions to be reflected separately, avoiding the bias caused by evaluating the service environment based on a single temperature and humidity index. It has the advantages of strong multi-factor coupling, high corrosion correlation, and evaluation results that are closer to the actual service environment.

[0019] 3. This invention proposes a method for constructing temperature and humidity equivalent relationships based on Mollier diagrams. This method can establish corresponding enthalpy databases and indoor equivalent environmental parameters based on regional environmental data of different target areas. This allows the module ratio and test cycle of salt spray test, damp heat test, and drying test to be adjusted according to changes in the service location. This results in customized temperature and humidity equivalent relationships for different regions and different material systems. While maintaining the correlation of corrosion mechanism, this method shortens the material corrosion evaluation cycle and has the advantages of strong regional adaptability, compressible test cycle, and wide applicability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This invention provides a flowchart illustrating a method for constructing the equivalent relationship between temperature and humidity based on a Mollier diagram. Figure 2 This is a schematic diagram of the temperature, humidity, and enthalpy relationship based on the Mollier diagram in the embodiment. Detailed Implementation

[0022] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0025] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details. Example

[0027] like Figure 1 As shown, this embodiment provides a method for constructing temperature and humidity equivalence relationships based on Mollier diagrams. This method establishes temperature and humidity equivalence relationships between the natural environment and the equivalent indoor environment based on natural environmental data of the target area. Using the enthalpy of moist air as the core equivalent parameter, it converts temperature and humidity changes, moisture state, and corrosive effects of pollutants in the target area into cumulative and calculable environmental effects. Based on this, it determines the test module, module parameters, and test cycle for the equivalent indoor environment. The method includes the following steps: S1. Collect environmental data; Collect hourly or daily environmental data for the target area for no less than one year. The environmental data includes air temperature T, relative humidity RH, rainfall information, condensation information, chloride ion deposition rate Sd, and sulfur dioxide pollution level Pc. Depending on the experimental needs, rainfall pH value and environmental pressure P can also be collected. The environmental pressure P is the actual measured pressure of the target area. Under standard atmospheric pressure conditions, 101325 Pa can also be used as appropriate.

[0028] The chloride ion deposition rate Sd can be obtained by dry film testing according to GB / T 19292.3-2018. The sulfur dioxide pollution level Pc can be determined based on the air pollution monitoring data of the target area. Rainfall information and condensation information are used to determine whether the material surface in the target area is wet.

[0029] S2, Correct the condition of the metal surface; Since the air temperature and relative humidity of the weather station cannot fully represent the actual corrosion interface state of the material surface, the collected air temperature T and relative humidity RH are corrected for the metal surface state to obtain the metal surface temperature and metal surface relative humidity corresponding to the metal corrosion interface.

[0030] In the specific correction process, the metal surface temperature is corrected in segments according to the time range in which the sampling time is located. The correction rules are shown in the table below: .

[0031] The relative humidity is calculated based on the corrected metal surface temperature and the corresponding saturated water vapor partial pressure to obtain the relative humidity of the metal surface. Through the above processing, the object for constructing the subsequent temperature and humidity equivalent relationship is transformed from the ordinary air environment to the surface environment that is closer to the metal corrosion interface.

[0032] S3. Establish a Mollier map enthalpy database for the target region; Using the metal surface temperature and relative humidity as inputs for the Mollier plot calculation, the enthalpy H of the moist air at each sampling time is calculated. The enthalpy H of the moist air is calculated according to the following formula: H =C pg · T +(Q g +C pq · T )· d / 1000; Where H is the enthalpy of a unit mass of moist air, T is the metal surface temperature, Cpg is the specific heat at constant pressure of dry air, Cpq is the specific heat at constant pressure of water vapor, Qg is the latent heat of vaporization of water at 0℃, and d is the absolute humidity.

[0033] The absolute humidity d is calculated using the following formula: d =621.9· φ ·P vs ( T ) / ( P - φ ·P vs ( T )); Where φ is the relative humidity of the metal surface, Pvs(T) is the saturated water vapor partial pressure at the metal surface temperature T, and P is the calculated pressure parameter.

[0034] The parameters for calculating the Mollier plot of the thermodynamic enthalpy-humidity relationship are shown in the table below: .

[0035] The metal surface temperature, relative humidity, and enthalpy of moist air corresponding to each sampling time are associated and stored in chronological order to form a sequence of annual enthalpy of moist air in the target area. Based on this sequence, a Mollier map enthalpy database for the target area is established.

[0036] At the same time, such as Figure 2 As shown, the Mollier map in the target area enthalpy database uses temperature as the horizontal parameter and absolute humidity as the vertical parameter. It represents the relationship between the enthalpy of moist air under different temperature and absolute humidity conditions through the enthalpy distribution. Different relative humidity curves are used to characterize the correspondence between temperature, absolute humidity and enthalpy under different relative humidity conditions. Based on this Mollier map, the metal surface temperature and relative humidity at each sampling time can be converted into the corresponding enthalpy of moist air, and a graphical calculation basis can be provided for the establishment of the annual enthalpy sequence of moist air in the target area.

[0037] S4. Divide the environmental process status throughout the year and statistically analyze the enthalpy contribution of each segment; Based on the Mollier map enthalpy database of the target area, the rainfall information, condensation information and relative humidity of the metal surface corresponding to each sampling time are determined point by point, and the annual environmental process is divided into dry state, humid air state and wet state.

[0038] When the rainfall information indicates no rainfall, the condensation information indicates no condensation, and the relative humidity of the metal surface is less than 70%, the corresponding sampling time is determined to be a dry state; when the rainfall information indicates no rainfall, the condensation information indicates no condensation, and the relative humidity of the metal surface is greater than or equal to 70% and less than 100%, the corresponding sampling time is determined to be a humid air state; when at least one of the following conditions is met: rainfall information indicates rainfall, condensation information indicates condensation, and the relative humidity of the metal surface reaches 100%, the corresponding sampling time is determined to be a wet state.

[0039] Sampling times belonging to the dry state are assigned to the dry state set, sampling times belonging to the humid air state set are assigned to the humid air state set, and sampling times belonging to the wet state set are assigned to the wet state set. The enthalpy values ​​of the humid air in each state set are accumulated and statistically analyzed to obtain the segmented enthalpy contributions of the dry state, the enthalpy contributions of the humid air state, and the enthalpy contributions of the wet state.

[0040] S5. Determine the total annual enthalpy and effective corrosion enthalpy; The total annual enthalpy is obtained by summing the contributions from the dry state, the humid air state, and the wetted state. The contribution from the humid air state is used as the humid air corrosion-sensitive enthalpy, and the contribution from the wetted state is converted to the wetting corrosion-sensitive enthalpy after wetting conversion. The effective corrosion enthalpy is determined based on both the humid air corrosion-sensitive enthalpy and the wetting corrosion-sensitive enthalpy. The wetting conversion involves converting the contribution from the wetted state according to a weight of 1 / 4.2. The effective corrosion enthalpy is the sum of the humid air corrosion-sensitive enthalpy and the converted wetting corrosion-sensitive enthalpy.

[0041] S6. Correcting the pollutant acceleration coefficient and determining the indoor equivalent environment; The pollutant acceleration coefficient Kp was determined based on the chloride ion deposition rate Sd, the sulfur dioxide pollution level Pc, and the electrochemical test results. The pollutant acceleration coefficient Kp was then used to correct the amount of pollutant corrosion acceleration in the equivalent indoor environment.

[0042] The concentration range of sodium sulfate (Na2SO4) in the equivalent indoor environment was determined based on the classification results of sulfur dioxide pollution level (Pc). The concentration range of sodium chloride (NaCl) in the equivalent indoor environment was determined based on the classification results of chloride ion deposition rate (Sd). When the sulfur dioxide pollution level (Pc) is at level P0, the concentration of sodium sulfate (Na2SO4) is 0–0.1%; when the sulfur dioxide pollution level (Pc) is at level P1, the concentration of sodium sulfate (Na2SO4) is 0.1%–0.5%; when the sulfur dioxide pollution level (Pc) is at level P2, the concentration of sodium sulfate (Na2SO4) is 0.5%–1.0%; and when the sulfur dioxide pollution level (Pc) is at level P3, the concentration of sodium sulfate (Na2SO4) is 1.0%–5.0%. When the chloride ion deposition rate Sd is at level S0, the sodium chloride (NaCl) concentration is 0–0.1%; when the chloride ion deposition rate Sd is at level S1, the sodium chloride (NaCl) concentration is 0.1%–0.5%; when the chloride ion deposition rate Sd is at level S2, the sodium chloride (NaCl) concentration is 0.5%–1.0%; and when the chloride ion deposition rate Sd is at level S3, the sodium chloride (NaCl) concentration is 1.0%–5.0%. After determining the concentration ranges of sodium sulfate (Na2SO4) and sodium chloride (NaCl), the test concentrations are selected within the corresponding ranges, and the acidity or alkalinity of the target test solution is adjusted based on the pH value of rainfall to form the target test solution used to determine the pollutant acceleration coefficient Kp.

[0043] The sulfur dioxide pollution classification and the Na2SO4 test concentration range are shown in the table below: .

[0044] The chloride ion deposition rate classification and the NaCl test concentration range are shown in the table below: .

[0045] The contaminant acceleration factor Kp is determined by the ratio of corrosion current density measured from the potentiodynamic polarization curve, and the calculation formula is as follows: That is, K p = i corr,s / i corr,0 ; in, i corr,s The corrosion current density in the target test solution, i corr,0 This represents the corrosion current density in deionized water.

[0046] The equivalent indoor environment includes salt spray test, drying test, and damp heat test. The temperature for the damp heat test and salt spray test is set at 20-25°C above the annual average metal surface temperature of the target area, and the test temperature is not lower than 25°C; the relative humidity for the damp heat test is set at 20% above the annual average relative humidity of the metal surface, and is controlled within the range of 70%-95%; the relative humidity for the drying test is set at 30%; and the relative humidity for the salt spray test is calculated as 100%.

[0047] The 24-hour cycle test procedure consists of salt spray test, drying test, damp heat test and drying test in sequence. The time ratio of each test module is determined according to the enthalpy ratio corresponding to the dry state, humid air state and wetted state.

[0048] The equivalent energy Eday for a 24-hour cycle is calculated as follows: E day =4.2·K p ·H ss ·t ss +H dry ·t dry +H wh ·t wh ; Among them, H ss H dry and H wh These are the base enthalpy values ​​for the salt spray, drying, and damp heat modules, respectively, t. ss t dry and t wh These represent the duration of the corresponding module; Target acceleration test days N according to E target / E day Confirmed, of which E target This refers to the total enthalpy value or effective corrosion enthalpy value for the whole year.

[0049] Taking the construction of the isoequivalence relationship of temperature and humidity in Wenchang, Hainan as an example Based on hourly meteorological data of Wenchang, Hainan in 2023, the temperature and humidity were corrected according to the metal surface temperature correction rules shown in Table 1 and the Goff-Gratch formula. The metal surface temperature and metal surface relative humidity were calculated, and the annual average metal surface temperature and the annual average metal surface relative humidity were further calculated.

[0050] In 2023, the sulfur dioxide concentration was 4.08 μg / m³, and the pH value of rainfall was 5.72. The chloride ion deposition rate was tested using the dry film method according to GB / T 19292.3-2018, and the result was 13.02 mg·m³. -2 ·d -1Based on hourly meteorological data, the annual dry time for metals, the annual humid air time for metals, and the annual wet time for metals were statistically obtained. These results serve as data on corrosive environmental factors in the Wenchang area of ​​Hainan Province. A summary of the specific information is as follows: .

[0051] Based on the data in the table above and the aforementioned design principles, the corresponding indoor equivalent environment module and test conditions for Wenchang, Hainan were determined. Since Wenchang, Hainan is characterized by high temperature, high humidity and chloride pollution, the NaCl system is preferred for the salt spray test, and the Na2SO4 concentration is set to 0.

[0052] The equivalent indoor environment module and test conditions in Wenchang, Hainan are as follows: .

[0053] Under these conditions, after enthalpy equivalent conversion and pollutant correction, the total energy value of the 24-hour cycle is 72779.88 kJ / kg; further, by ratio conversion with the annual energy value of 660636.29 kJ / kg, the equivalent accelerated test days are approximately 9 days.

[0054] Therefore, the equivalent indoor acceleration environment in Wenchang, Hainan is shown in the table below: .

[0055] By adopting the above environmental spectrum, an indoor equivalent simulation of the typical marine atmospheric corrosion environment in Wenchang, Hainan can be achieved in a relatively short period of time. This is applicable to the accelerated evaluation and service-related analysis of metal substrates and coating systems.

[0056] In summary, the natural environmental data of the target area in Wenchang, Hainan, was converted into corresponding indoor equivalent environmental parameters through the enthalpy of moist air, environmental state classification, and accelerated correction of pollutants. This established an equivalent relationship of temperature and humidity between the natural environment and the indoor equivalent environment in Wenchang, Hainan. Using the above-mentioned indoor equivalent environment, an equivalent simulation of the typical marine atmospheric corrosion environment in Wenchang, Hainan, can be achieved in a relatively short period of time. This method is suitable for accelerated evaluation and service correlation analysis of metal substrates, coating materials, and coating materials.

[0057] Further evidence shows that, after the environmental data of the target area in this invention is corrected for metal surface condition, accumulated enthalpy of moist air, classified environmental condition, and corrected for pollutant acceleration, it can form indoor equivalent environmental parameters corresponding to the natural service environment of the target area. The indoor equivalent environment reflects the overall cumulative level of temperature and humidity effects throughout the year, and also takes into account the corrosion sensitivity effects of humid air and wet conditions. At the same time, it considers the influence of chloride ions and sulfur dioxide pollutants on the corrosion acceleration process, thereby determining the temperature and humidity equivalence relationship between the natural environment and the indoor equivalent environment, providing quantifiable experimental basis for subsequent corrosion acceleration evaluation.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for constructing the equivalent relationship of temperature and humidity based on Mollier diagrams, characterized in that, Includes the following steps: S1. Collect environmental data of the target area, including air temperature, relative humidity, rainfall information, condensation information, chloride ion deposition rate and sulfur dioxide pollution level; S2. Correct the air temperature and relative humidity for metal surface condition to obtain the metal surface temperature and metal surface relative humidity corresponding to the metal corrosion interface; S3. Using metal surface temperature and relative humidity as inputs for Mollier plot calculation, calculate the enthalpy of moist air at each sampling time based on the relationship between enthalpy and moist air. Store the metal surface temperature, relative humidity and enthalpy of moist air at each sampling time in chronological order to form a sequence of enthalpy of moist air throughout the year for the target area. Establish a Mollier plot enthalpy database for the target area based on the sequence of enthalpy of moist air throughout the year for the target area. S4. Based on the Mollier map enthalpy database of the target area, the rainfall information, condensation information and relative humidity of the metal surface corresponding to multiple sampling times are determined point by point. The annual environmental process is divided into dry state, humid air state and wet state. The sampling times belonging to the dry state are assigned to the dry state set, the sampling times belonging to the humid air state set are assigned to the humid air state set, and the sampling times belonging to the wet state set are assigned to the wet state set. The enthalpy values ​​of the humid air in the above state sets are accumulated and statistically analyzed to obtain the segmented enthalpy contribution of the dry state, the segmented enthalpy contribution of the humid air state, and the segmented enthalpy contribution of the wet state. S5. The enthalpy contributions of the dry state segment, the enthalpy contributions of the humid air state segment, and the enthalpy contributions of the wetted state segment are summed to obtain the total enthalpy value for the whole year. The enthalpy contribution of the humid air state segment is used as the enthalpy value sensitive to humid air corrosion. The enthalpy contribution of the wetted state segment is converted to wettability and used as the enthalpy value sensitive to wetting corrosion. The effective corrosion enthalpy value is determined based on the enthalpy value sensitive to humid air corrosion and the enthalpy value sensitive to wetting corrosion. S6. Determine the pollutant acceleration coefficient based on the chloride ion deposition rate, sulfur dioxide pollution level, and electrochemical test results. Use the pollutant acceleration coefficient to correct the amount of pollutant corrosion acceleration in the indoor equivalent environment. Then, based on the total annual enthalpy, effective corrosion enthalpy, and the indoor equivalent environment corrected by the pollutant acceleration coefficient, determine the temperature and humidity equivalence relationship between the natural environment and the indoor equivalent environment.

2. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 1, characterized in that: In step S4, when the rainfall information indicates that no rainfall has occurred, the condensation information indicates that no condensation has occurred, and the relative humidity of the metal surface is less than 70%, the corresponding sampling time is determined to be a dry state. When the rainfall information indicates no rainfall, the condensation information indicates no condensation, and the relative humidity of the metal surface is greater than or equal to 70% and less than 100%, the corresponding sampling time is determined to be a humid air state; when at least one of the following conditions is met: rainfall information indicates rainfall, condensation information indicates condensation, and the relative humidity of the metal surface reaches 100%, the corresponding sampling time is determined to be a wetted state.

3. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 2, characterized in that, In step S3, the enthalpy of the moist air is calculated according to the following formula: H =C pg · T +(Q g +C pq · T )· d / 1000; Where H is the enthalpy of a unit mass of moist air, T is the metal surface temperature, Cpg is the specific heat at constant pressure of dry air, Cpq is the specific heat at constant pressure of water vapor, Qg is the latent heat of vaporization of water at 0℃, and d is the absolute humidity.

4. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 3, characterized in that, The absolute humidity d is calculated according to the following formula: d =621.9· φ ·P vs ( T ) / ( P - φ ·P vs ( T )); in, φ P represents the relative humidity of the metal surface. vs ( T ) represents the surface temperature of the metal. T The partial pressure of saturated water vapor under the given conditions, where P is the calculated pressure parameter.

5. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 4, characterized in that: In step S2, the air temperature is segmented and corrected according to the time range of the sampling time to obtain the metal surface temperature, and the relative humidity is calculated based on the saturated water vapor partial pressure corresponding to the metal surface temperature to obtain the relative humidity of the metal surface.

6. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 5, characterized in that, In step S5, the wetting conversion is to convert the contribution of the segmented enthalpy value of the wetting state according to a weight of 1 / 4.2, and the effective corrosion enthalpy value is the sum of the enthalpy value of corrosion sensitivity of humid air and the converted wetting corrosion sensitivity enthalpy value.

7. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 6, characterized in that: In step S6, the concentration range of sodium sulfate (Na2SO4) in the indoor equivalent environment is determined based on the classification results of sulfur dioxide pollution levels, and the concentration range of sodium chloride (NaCl) in the indoor equivalent environment is determined based on the classification results of chloride ion deposition rates. A test concentration is then selected within the concentration ranges of sodium sulfate (Na2SO4) and sodium chloride (NaCl) to form a target test solution for determining the pollutant acceleration coefficient.

8. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 7, characterized in that: The pollutant acceleration coefficient K in step S6 p The corrosion current density ratio, K, is determined by measuring the potentiodynamic polarization curve. p = i corr,s / i corr,0 ; in, i corr,s The corrosion current density in the target test solution, i corr,0 This represents the corrosion current density in deionized water.

9. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 8, characterized in that: In step S6, the temperature of the damp heat test and the salt spray test is set according to the annual average metal surface temperature of the target area plus 20-25°C, and the test temperature is not lower than 25°C. The relative humidity of the damp heat test is set according to the annual average relative humidity of the metal surface plus 20%, and is controlled within the range of 70%-95%. The relative humidity of the drying test is set to 30%, and the relative humidity of the salt spray test is calculated as 100%.

10. The method for constructing the equivalent relationship of temperature and humidity based on the Mollier diagram according to claim 9, characterized in that: The 24-hour cycle test process in step S6 consists of salt spray test, drying test, damp heat test and drying test in sequence. The time ratio of each test module is determined according to the enthalpy ratio corresponding to the dry state, humid air state and wetted state. The equivalent energy Eday for a 24-hour cycle is calculated as follows: E day =4.2·K p ·H ss ·t ss +H dry ·t dry +H wh ·t wh; Among them, H ss H dry and H wh These are the base enthalpy values ​​for the salt spray, drying, and damp heat modules, respectively, t. ss t dry and t wh These represent the duration of the corresponding module; Target acceleration test days N according to E target / E day Confirmed, of which E target This refers to the total enthalpy value or effective corrosion enthalpy value for the whole year.

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