Dynamic air volume adjusting method and device for grain storage ventilation system

Abstract

The invention relates to the technical field of grain storage ventilation control, discloses an air volume dynamic adjusting method and device of a grain storage ventilation system, and aims at solving the problem that an existing grain storage ventilation control mode is poor in accuracy. Comprising grain layer average temperature gradient, average grain temperature, average grain temperature difference between an air inlet layer and an exhaust layer, grain pile balance desorption absolute humidity under instant grain temperature and instant atmospheric absolute humidity; the state index of each grain pile partition is calculated in real time, the corresponding target ventilation quantity is determined, and the corresponding air valve is dynamically adjusted to the target opening degree corresponding to the target ventilation quantity; and when the grain pile partition is ventilated according to the target opening degree, the ventilation wind speed is calculated in real time, the moisture evaporation rate of the grain pile partition is calculated in real time based on a Penman-Monteith equation, and the target ventilation quantity is dynamically corrected according to the moisture evaporation rate. The accuracy of grain storage ventilation control is improved, and the method is particularly suitable for granaries in complex climate areas.

Description

Technical Field

[0001] The present invention relates to the technical field of grain storage ventilation control, and particularly relates to a method and device for dynamically adjusting the air volume of a grain storage ventilation system. Background Art

[0002] Grain storage ventilation is a technology that introduces low-temperature and low-humidity external air into the grain pile through mechanical devices to achieve the heat and moisture exchange of gases inside and outside the grain pile, thereby regulating the grain temperature, moisture, and gas environment. Its core goal is to maintain the stability of grain storage and extend the shelf life. Precise adjustment of the air volume can match the actual needs of the grain pile, balance the cooling rate and water loss, ensure uniform heat and moisture exchange, simultaneously achieve multiple effects such as cooling, dehumidification, and pest control, avoid economic losses caused by excessive dehydration, reduce the risk of grain spoilage, and also avoid energy waste caused by excessive ventilation.

[0003] In the prior art, there are mainly two conventional ventilation control schemes. The first is to use a high-power fan with a fixed air volume for long-term ventilation. Although this method can quickly cool down, it cannot dynamically adjust according to the grain state, has poor accuracy, and is prone to excessive water loss of the grain. For example, water loss may be aggravated in high-temperature and dry climates, and the grain pile's moisture absorption cannot be effectively inhibited in the rainy and high-humidity environment. At the same time, the continuous operation of the high-power fan consumes extremely high energy, resulting in a significant increase in electricity costs in the long term, and the long-term high-load operation will accelerate the wear of the fan's mechanical components, increasing the failure rate and maintenance costs. The second is to control the start and stop of the fan by monitoring the temperature and humidity of the grain pile and based on the temperature and humidity thresholds. This method that only relies on the temperature and humidity thresholds cannot effectively coordinate the parameter relationships such as the atmospheric dew point and the equilibrium humidity of the grain pile, and still has the problem of insufficient accuracy. For example, if the ventilation does not synchronously consider the difference between the external humidity and the moisture content of the grain pile, it may lead to excessive dehumidification or ineffective ventilation. At the same time, the fixed threshold is difficult to adapt to the differences in ventilation requirements due to seasonal changes. In the low-temperature environment in winter, starting the fan only according to the temperature threshold may cause energy waste; in summer when it is hot, simply cooling down may ignore the promotion of humidity on microbial activities, and the frequent start and stop of the fan may lead to non-uniform water loss of the grain pile. Especially when the power of the ventilation equipment is too high or the operation duration is out of control, it is easy to damage the processing quality of the grain. Summary of the Invention

[0004] The present invention aims to solve the problem of poor accuracy in the existing grain storage ventilation control method, and proposes a method and device for dynamically adjusting the air volume of a grain storage ventilation system.

[0005] The technical solutions adopted by the present invention to solve the above technical problems are as follows: In a first aspect, the present invention provides a method for dynamically adjusting the air volume of a grain storage ventilation system. The grain storage ventilation system includes a damper for controlling the ventilation volume of the corresponding grain pile partition. The method includes: Detect the status parameters of each grain pile partition in real time, where the status parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the air inlet layer and the exhaust layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere; Calculate the status index of each grain pile partition in real time according to the status parameters, determine the corresponding target ventilation volume according to the status index, and dynamically adjust the corresponding air valve to the target opening corresponding to the target ventilation volume; When ventilating the grain pile partition according to the target opening, calculate the ventilation wind speed in real time, calculate the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value and based on the Penman-Monteith equation, and dynamically correct the target ventilation volume according to the moisture evaporation rate.

[0006] Further, the detection methods for the average temperature gradient of the grain layer, the average grain temperature, and the average grain temperature difference between the air inlet layer and the exhaust layer include: Set up a temperature and humidity sensor matrix in the grain pile partition, and calculate the average temperature gradient of the grain layer, the average grain temperature, and the average grain temperature difference between the air inlet layer and the exhaust layer of the grain pile partition according to the temperature values detected by each temperature and humidity sensor in the temperature and humidity sensor matrix.

[0007] Further, the detection methods for the absolute humidity of grain pile equilibrium desorption at the instant grain temperature and the absolute humidity of the instant atmosphere include: Determine the grain type and grain moisture content, and determine the absolute humidity of grain pile equilibrium desorption at the instant grain temperature according to the grain type, grain moisture content, and average grain temperature and based on the CAE equation or the equilibrium desorption absolute humidity curve graph; Detect the water vapor density in the air in real time through an absolute humidity sensor to obtain the absolute humidity of the instant atmosphere.

[0008] Further, the calculation formula for the status index is as follows: ; Among them, represents the status index, represents the average grain temperature, represents the average grain temperature difference between the air inlet layer and the exhaust layer, represents the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, represents the absolute humidity of the instant atmosphere, represents the average temperature gradient of the grain layer, and respectively represent the corresponding weights.

[0009] Further, determining the corresponding target ventilation volume according to the status index includes: Pre - construct a first mapping relationship between the state index and the target ventilation volume under the test environment, and determine the target ventilation volume corresponding to the state index according to the first mapping relationship.

[0010] Further, the calculation method of the ventilation wind speed includes: Determine the cross - sectional area of the grain pile in the grain pile partition, detect the actual ventilation volume of the current grain pile partition, and calculate the ventilation wind speed according to the actual ventilation volume and the cross - sectional area of the grain pile.

[0011] Further, the calculation formula of the moisture evaporation rate is as follows: ; Wherein, represents the moisture evaporation rate, represents the slope of the saturation vapor pressure - temperature curve, represents the net radiation, represents the internal heat conduction flux of the grain pile, represents the humidity constant, represents the average grain temperature, represents the ventilation wind speed, represents the saturation vapor pressure, represents the actual vapor pressure, k represents the correction coefficient of the grain pile evapotranspiration under different ventilation volumes.

[0012] Further, dynamically correct the target ventilation volume according to the moisture evaporation rate, including: Determine a second mapping relationship between the moisture evaporation rate and the ventilation volume correction value in the experimental environment, determine the ventilation volume correction value corresponding to the moisture evaporation rate in real - time according to the second mapping relationship, and dynamically correct the target ventilation volume according to the ventilation volume correction value.

[0013] Further, the method further includes: Judge whether there is humidity abnormality or temperature abnormality according to the temperature values and humidity values detected by each temperature - humidity sensor in the temperature - humidity sensor matrix. If so, issue a humidity warning or a temperature warning, and judge whether there is excessive moisture loss according to the moisture evaporation rate. If so, issue an alarm for excessive moisture loss.

[0014] In a second aspect, the present invention provides a device for dynamically adjusting the air volume of a grain storage ventilation system. The grain storage ventilation system includes a wind valve for controlling the ventilation volume of the corresponding grain pile partition. The device includes: A detection module for real - time detecting the state parameters of each grain pile partition. The state parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the intake layer and the exhaust layer, the absolute humidity of the grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere. A control module is configured to calculate the state index of each grain pile partition in real time according to various state parameters, determine the corresponding target ventilation volume according to the state index, and dynamically adjust the corresponding air valve to the target opening corresponding to the target ventilation volume; when ventilating the grain pile partition according to the target opening, calculate the ventilation wind speed in real time, calculate the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value based on the Penman-Monteith equation, and dynamically correct the target ventilation volume according to the moisture evaporation rate.

[0015] The beneficial effects of the present invention are as follows: The method and device for dynamically adjusting the air volume of the grain storage ventilation system provided by the present invention dynamically regulate the ventilation volume based on the state index of the grain pile, avoiding energy waste caused by long-term high-load operation of high-power equipment, reducing equipment failure rate and maintenance cost. The state index is calculated based on multiple state parameters, and multiple state parameters fully consider temperature gradient, average grain temperature, ventilation uniformity, moisture evaporation, and environmental humidity, so that the calculated state index can more accurately reflect the state of the grain pile, thereby improving the accuracy of ventilation control, avoiding abnormal evaporation of grain moisture caused by excessive ventilation, ensuring uniform air flow coverage of the grain pile, reducing the risk of local water loss, and at the same time, by accurately dynamically adjusting the ventilation volume, a stable microenvironment can be formed in the grain pile, which can disrupt the pest reproduction cycle and reduce the dependence on chemical fumigation. In addition, the present invention also calculates the moisture evaporation rate during ventilation according to the grain pile state and ventilation conditions, and dynamically corrects the ventilation volume according to the moisture evaporation rate, further improving the accuracy of ventilation control and avoiding abnormal evaporation of grain moisture caused by ventilation. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a grain storage ventilation system provided for an embodiment; Figure 2 It is a schematic flow diagram of a method for dynamically adjusting the air volume of a grain storage ventilation system provided for an embodiment. Detailed Embodiments

[0017] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the present embodiment will be clearly and completely described below in conjunction with the drawings in the present embodiment.

[0018] In some processes described in the specification of the present invention and the above-mentioned drawings, there are multiple operations that appear in a specific order. However, it should be clearly understood that these operations may not be executed in the order in which they appear in this article or may be executed in parallel. The serial numbers of the operations are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations may be executed in sequence or in parallel.

[0019] The technical solution of the present invention is applicable to application scenarios that require control of grain storage ventilation, especially scenarios such as high-piled granaries and complex climate regions.

[0020] Since the current control method for grain storage ventilation basically uses high-power fans with fixed air volume for long-term ventilation or controls the start and stop of the fans by monitoring the temperature and humidity of the grain pile and based on temperature and humidity thresholds, the inventor found, through experimental research on the existing grain storage ventilation control method, that the existing grain storage ventilation control method has at least the problems of energy waste, high equipment failure rate and maintenance cost, and poor accuracy.

[0021] Based on this, the technical solution of the present invention is proposed. In the present invention, the grain storage ventilation system includes a damper for controlling the ventilation volume of the corresponding grain pile partition. The method for dynamically adjusting the air volume of the grain storage ventilation system includes: detecting the state parameters of each grain pile partition in real time, where the state parameters include the average grain temperature, the average grain temperature difference between the intake layer and the exhaust layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere; calculating the state index of each grain pile partition in real time according to each state parameter, determining the corresponding target ventilation volume according to the state index, and dynamically adjusting the corresponding damper to the target opening corresponding to the target ventilation volume; when ventilating the grain pile partition according to the target opening, calculating the ventilation wind speed in real time, calculating the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value and based on the Penman-Monteith equation, and dynamically correcting the target ventilation volume according to the moisture evaporation rate.

[0022] Specifically, first, the present invention calculates the state index of each grain pile partition in real time according to multiple state parameters, determines the target ventilation volume based on the state index, and dynamically controls the air valve according to the target ventilation volume, thereby realizing the dynamic control and adjustment of grain storage ventilation. Among the multiple state parameters, the average temperature gradient of the grain layer refers to the average temperature change value per unit thickness (usually 1 meter) in the vertical direction of the grain pile, reflecting the temperature stability in the grain storage environment; the average grain temperature is the core index of grain storage safety. Controlling the average grain temperature can inhibit biological activity and delay quality deterioration. The average grain temperature difference between the intake layer and the exhaust layer is a key index reflecting the operation state of the ventilation system and the thermal dynamic balance of the grain pile, which can reflect the ventilation uniformity and the trend of heat accumulation or dissipation; the absolute humidity of grain pile equilibrium desorption at the instant grain temperature is a key parameter reflecting the dynamic balance of water vapor exchange between the grain pile and the external environment, which can reflect the moisture stability of the grain pile; the instant atmospheric absolute humidity reflects the actual density of water vapor content in the current environment. There is a balance relationship between grain moisture and air humidity, and the instant atmospheric absolute humidity can affect the moisture absorption or desorption of grains. The multiple state parameters in the present invention fully consider the average temperature gradient of the grain layer, the average grain temperature, the ventilation uniformity, the moisture evaporation situation, and the environmental humidity, so that the calculated state index can more accurately reflect the state of the grain pile, thereby achieving the purpose of improving the accuracy of ventilation control. Secondly, during the ventilation process, the present invention also calculates the moisture evaporation rate and corrects the ventilation volume in real time according to the moisture evaporation rate, thereby dynamically balancing the moisture migration, avoiding over-drying or moisture absorption, and further improving the accuracy of ventilation control.

[0023] Next, the technical solutions in this embodiment will be clearly and completely described in conjunction with the accompanying drawings in this embodiment. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0024] Figure 1 shows a schematic structural diagram of a grain storage ventilation system. Please refer to Figure 1 , the granary includes multiple grain pile partitions, namely grain pile partition 1, grain pile partition 2,..., grain pile partition N. The granary is provided with a fan, and each grain pile partition is correspondingly provided with an air valve. Grain pile partition 1 is correspondingly provided with air valve 1, grain pile partition 2 is correspondingly provided with air valve 2,..., grain pile partition N is correspondingly provided with air valve N. Each air valve is connected to the fan through a pipeline, and the air valve is used to adjust the ventilation volume of the corresponding grain pile partition.

[0025] Please refer to Figure 2 , based on the above grain storage ventilation system, the method for dynamically adjusting the air volume of the grain storage ventilation system provided in this embodiment includes the following steps: Step 1: Detect the state parameters of each grain pile partition in real time. The state parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the intake layer and the exhaust layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the instant atmospheric absolute humidity.

[0026] In this embodiment, a temperature and humidity sensor matrix is arranged in the grain heap in zones, and the average temperature gradient of the grain layers in the grain heap zones, the average grain temperature, and the average grain temperature difference between the intake layer and the exhaust layer are calculated according to the temperature values detected by the temperature and humidity sensors in the temperature and humidity sensor matrix.

[0027] Specifically, since the grain heap is usually large in volume, there may be differences in temperature and humidity at different positions, especially between the deep layer and the surface layer, or there may be local heating points. Therefore, in this embodiment, a temperature and humidity sensor matrix arranged inside the grain heap is used to detect the temperature values and humidity values at multiple monitoring points. Multi-point monitoring can cover the entire grain heap and avoid dead corners. The average temperature gradient of the grain layers in the grain heap, the average grain temperature, and the average grain temperature difference between the intake layer and the exhaust layer can be obtained by calculating based on the temperature values at each monitoring point. The average temperature gradient of the grain layers is the average temperature value per unit thickness in the vertical direction of the grain heap, the average grain temperature of the grain heap is the average temperature value of all monitoring points, and the average grain temperature difference between the intake layer and the exhaust layer is the difference between the average temperature value of all monitoring points in the intake layer and the average temperature value of all monitoring points in the exhaust layer.

[0028] In this embodiment, the method for detecting the absolute humidity of grain heap desorption equilibrium at the instant grain temperature includes: determining the grain type and grain moisture content, and determining the absolute humidity of grain heap desorption equilibrium at the instant grain temperature based on the grain type, grain moisture content, and average grain temperature and using the CAE equation or the absolute humidity curve graph of desorption equilibrium.

[0029] In practical applications, after obtaining the grain type (such as wheat, paddy, or corn) and the grain moisture content (such as 12.5% for paddy), inputting the grain type, grain moisture content, and average grain temperature into the programmed CAE equation software can directly output the absolute humidity of grain heap desorption equilibrium (such as 15 g / m³). In addition, based on the pre-drawn absolute humidity curve graph of desorption equilibrium, the average grain temperature can be horizontally located in the corresponding grain type curve graph, and then the absolute humidity value of desorption equilibrium can be vertically read in combination with the grain moisture content. The absolute humidity curve graph of desorption equilibrium belongs to a calibrated standardized graph, and the drawing method belongs to the prior art, which will not be elaborated in this embodiment.

[0030] In this embodiment, the method for detecting the instant atmospheric absolute humidity includes: detecting the water vapor density in the air in real time through an absolute humidity sensor to obtain the instant atmospheric absolute humidity.

[0031] In practical applications, an absolute humidity sensor can be set in the air. The absolute humidity sensor utilizes the absorption characteristics of water vapor for infrared light with a specific wavelength to determine the water vapor density in the air, and then obtains the instant atmospheric absolute humidity.

[0032] Among the state parameters selected in this embodiment, the average temperature gradient of the grain layer can help identify the temperature difference at different depths of the grain pile. If the gradient is abnormal (such as too large temperature difference between the upper and lower layers), it may indicate local heating (such as mildew, pest activity) or uneven ventilation. Moreover, the average temperature gradient of the grain layer will cause air convection inside the grain pile, and the moisture in the high-temperature area will move to the low-temperature area (such as the top of the grain pile is prone to condensation due to low temperature). The average grain temperature of the grain pile is the core index for the safety of stored grain, which can reflect the overall thermal state of the grain storage environment. If the average grain temperature of the grain pile exceeds the safety threshold (such as 15 °C), it may accelerate the respiration of the grain, resulting in fat oxidation or starch hydrolysis. Controlling the average grain temperature within an appropriate range can inhibit biological activity and delay the deterioration of quality. The average grain temperature difference between the air inlet layer and the exhaust layer is a key index reflecting the operation state of the ventilation system and the thermal dynamic balance of the grain pile, which can reflect the ventilation uniformity and the trend of heat accumulation or dissipation. If the grain temperature difference between the air inlet layer and the exhaust layer is small, it indicates that the air flow distribution is uniform and the ventilation system effectively realizes the uniform heat exchange inside the grain pile; otherwise, there may be local air flow short circuit or dead angle. When the temperature of the air inlet layer is significantly lower than that of the exhaust layer, it indicates that the external cold air fully absorbs the heat of the grain pile and then is discharged, playing a role in cooling. The absolute equilibrium desorption humidity of the grain pile at the instant grain temperature is a key parameter reflecting the dynamic balance of water vapor exchange between the grain pile and the external environment, which can reflect the moisture stability of the grain pile. When the relative humidity corresponding to the absolute equilibrium desorption humidity exceeds 65%, it indicates that the grain moisture has approached or exceeded the safety threshold, which may cause microbial reproduction and quality deterioration. The instant atmospheric absolute humidity reflects the actual density of the water vapor content in the current environment. There is a balance relationship between the grain moisture and the air humidity, and the instant atmospheric absolute humidity can affect the moisture absorption or desorption of the grain. For example, when the atmospheric absolute humidity is higher than the absolute equilibrium desorption humidity of the grain pile, the grain may absorb moisture, and vice versa, it will desorb.

[0033] Step 2: Calculate the state index of each grain pile partition in real time according to each state parameter, determine the corresponding target ventilation volume according to the state index, and dynamically adjust the corresponding air valve to the target opening corresponding to the target ventilation volume.

[0034] In this embodiment, the calculation formula of the state index is as follows: ; Among them, represents the state index, represents the average grain temperature, represents the average grain temperature difference between the air inlet layer and the exhaust layer, represents the absolute equilibrium desorption humidity of the grain pile at the instant grain temperature, represents the instant atmospheric absolute humidity, represents the average temperature gradient of the grain layer, and respectively represent the corresponding weights, and the weights can be dynamically adjusted based on historical data using the reinforcement learning Q-learning algorithm.

[0035] After determining the state index of the grain pile partition, the corresponding target ventilation volume can be determined according to the state index. In this embodiment, a first mapping relationship between the state index and the target ventilation volume can be pre-constructed in a test environment. After obtaining the state index of the grain pile partition through real-time calculation, the target ventilation volume corresponding to the state index can be determined using the first mapping relationship.

[0036] After determining the target ventilation volume of the grain pile partition, the target opening degree of the corresponding air valve can be determined according to the target ventilation volume and using the preset corresponding relationship, and then the corresponding air valve can be dynamically adjusted to the target opening degree, thereby realizing the dynamic adjustment of the ventilation volume.

[0037] Calculating the state index of the grain pile partition through the above state parameters can fully consider the temperature gradient, average grain temperature, ventilation uniformity, moisture evaporation situation, and environmental humidity, improving the accuracy of the state index and the target ventilation volume, and further improving the accuracy of ventilation control.

[0038] Step 3: When ventilating the grain pile partition according to the target opening degree, calculate the ventilation wind speed in real time, calculate the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value based on the Penman-Monteith equation, and dynamically correct the target ventilation volume according to the moisture evaporation rate.

[0039] In this embodiment, the calculation method of the ventilation wind speed includes: determining the cross-sectional area of the grain pile in the grain pile partition, and detecting the current actual ventilation volume of the grain pile partition, and calculating the ventilation wind speed according to the actual ventilation volume and the cross-sectional area of the grain pile.

[0040] In practical applications, there may be a difference between the target ventilation volume and the actual ventilation volume. To improve the calculation accuracy, in this embodiment, the ventilation wind speed can be obtained by the ratio of the actual ventilation volume to the cross-sectional area of the grain pile, where the cross-sectional area of the grain pile refers to the cross-sectional area through which the air flow vertically passes through the grain pile, that is, the area of the vertical plane in the ventilation direction.

[0041] In this embodiment, the calculation formula of the moisture evaporation rate is constructed based on the Penman-Monteith equation. This equation is the reference evapotranspiration estimation standard method recommended by the Food and Agriculture Organization of the United Nations. Corresponding adjustments need to be made to the formula when it is applied to the grain pile, as follows: ; where represents the moisture evaporation rate (mm / day), represents the slope of the saturated water vapor pressure-temperature curve (kPa / ℃), represents net radiation (MJ / m² / day), represents the heat conduction flux inside the grain bulk (MJ / m² / day), represents the humidity constant (≈0.066 kPa / °C), represents the average grain temperature (°C), represents the ventilation wind speed (m / s), represents the saturation vapor pressure (kPa), represents the actual vapor pressure (kPa), represents the correction coefficient of the evapotranspiration of the grain bulk under different ventilation rates (dimensionless).

[0042] In the above formula, the slope of the saturation vapor pressure - temperature curve can be obtained by looking up a table or calculated based on the saturation vapor pressure and the average grain temperature; the grain bulk is a closed static system, and the influence of solar radiation can be ignored, so = 0; the saturation vapor pressure can be queried from the temperature - saturation vapor pressure table or calculated according to an empirical formula, and the actual vapor pressure can be calculated based on the relative humidity and the saturation vapor pressure; the resistance coefficient of the grain bulk can be obtained by experimentally calibrating the aerodynamic resistance of the grain bulk under different ventilation conditions, and the value can be deduced by combining the measured water evaporation data.

[0043] In the above formula, 0.408 represents the reciprocal of the latent heat of vaporization of water The latent heat of vaporization of water is approximately 2.45 MJ / kg, so 1 / 2.45 = 1 / ≈ 0.408, which is a coefficient used to convert the energy unit (MJ) to the equivalent evaporation water depth (mm) (1 MJ / m² / day ≈ 0.408 mm / day); 900 represents the comprehensive parameter in the aerodynamic term (dimensionless), which involves air density, specific heat capacity, gas constant, etc., and is used to convert the wind speed and the vapor pressure difference into the evapotranspiration contribution term; 273 is used to convert Celsius (°C) to Kelvin temperature (K) to meet the requirement for absolute temperature in thermodynamic calculations, that is, K = °C + 273.

[0044] The heat conduction flux inside the grain bulk is calculated as follows: ; where represents the average temperature gradient of the grain layer in the grain bulk partition, represents the thermal conductivity of the grain bulk.

[0045] The slope of the saturation vapor pressure - temperature curve is calculated as follows: ; Among them, 4098 is an empirical constant (unit: °C), which is derived from the coefficient combination in the Tetens formula (approximate value); 237.3 represents the empirical constant in the Tetens formula (unit: °C).

[0046] Saturation water vapor pressure The calculation formula is as follows: ; Among them, represents the exponential function with the natural constant as the base; 0.6108 is used to adjust the dimension of the formula output (unit: kPa) to match the saturation water vapor pressure observed in the experiment. At 0.01 °C (the triple point temperature of water), the theoretical saturation water vapor pressure is about 0.6108 kPa; 17.27 is an empirical coefficient (dimensionless) obtained by fitting experimental data, which is used to adjust the fitting accuracy of the exponential function for the saturation water vapor pressure - temperature curve.

[0047] Actual water vapor pressure The calculation formula is as follows: ; Among them, represents the average humidity of the grain pile, which can be obtained by calculating the humidity values of all monitoring points detected by the temperature and humidity sensor matrix. The value 100 is used to convert the percentage to a decimal form.

[0048] After calculating the water evaporation rate, the target ventilation volume can be corrected according to the water evaporation rate, so as to determine the new target opening of the air valve according to the corrected target ventilation volume again. It can be understood that the water evaporation rate reflects the actual water release intensity of the grain pile. When the evaporation rate is high, appropriately reducing the ventilation volume can avoid the increase in the bursting waist and breakage rate of grain caused by excessive drying; when the evaporation rate is low, increasing the ventilation volume can accelerate the discharge of moisture and inhibit the risk of local condensation and mildew. Based on this, in this embodiment, correcting the target ventilation volume according to the water evaporation rate can keep the water evaporation rate within an appropriate range, avoid excessive drying or excessive wetting, and further improve the accuracy of ventilation control.

[0049] In this embodiment, the method further includes: judging whether there is humidity abnormality or temperature abnormality according to the temperature values and humidity values detected by each temperature and humidity sensor in the temperature and humidity sensor matrix. If so, a humidity warning or a temperature warning is issued, and judging whether there is excessive water loss according to the water evaporation rate. If so, an excessive water loss alarm is issued.

[0050] In practical applications, a real-time mapping of the three-dimensional temperature and humidity field and air flow distribution of the grain pile can be constructed based on the temperature, humidity, and actual ventilation volume of each monitoring point, dynamically reflecting the internal environmental changes of the grain pile. When temperature and humidity anomalies or excessive moisture loss occur, an alarm is automatically triggered and the management personnel are notified by means of text messages, APP push, etc., so as to shorten the response time, achieve rapid regulation in case of temperature and humidity anomalies, and avoid the decline of grain quality.

[0051] In summary, the method for dynamically adjusting the air volume of the grain storage ventilation system provided in this embodiment dynamically regulates the ventilation volume based on the state index of the grain pile, avoiding the waste of energy caused by the long-term high-load operation of high-power equipment, reducing the equipment failure rate and maintenance cost. The state index is calculated based on multiple state parameters, and multiple state parameters fully consider the average grain temperature, ventilation uniformity, moisture evaporation situation, and environmental humidity, so that the calculated state index can more accurately reflect the state of the grain pile, thereby improving the accuracy of ventilation control, avoiding abnormal evaporation of grain moisture caused by excessive ventilation, and ensuring that the air flow evenly covers the grain pile, reducing the risk of local water loss. At the same time, by accurately dynamically adjusting the ventilation volume, a stable microenvironment can be formed in the grain pile, which can disrupt the pest reproduction cycle and reduce the dependence on chemical fumigation. In addition, the present invention also calculates the moisture evaporation rate during the ventilation process according to the state of the grain pile and the ventilation situation, and dynamically corrects the ventilation volume according to the moisture evaporation rate, further improving the accuracy of ventilation control and avoiding abnormal evaporation of grain moisture caused by ventilation.

[0052] Based on the above technical solution, this embodiment also proposes a device for dynamically adjusting the air volume of a grain storage ventilation system. The grain storage ventilation system includes a damper for controlling the ventilation volume of the corresponding grain pile partition. The device includes: A detection module for real-time detecting the state parameters of each grain pile partition. The state parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the intake layer and the exhaust layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere. A control module for calculating the state index of each grain pile partition in real time according to each state parameter, determining the corresponding target ventilation volume according to the state index, and dynamically adjusting the corresponding damper to the target opening corresponding to the target ventilation volume; when ventilating the grain pile partition according to the target opening, calculating the ventilation wind speed in real time, calculating the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value based on the Penman-Monteith equation, and dynamically correcting the target ventilation volume according to the moisture evaporation rate.

[0053] It can be understood that since the air volume dynamic adjustment device of the grain storage ventilation system described in this embodiment is a device for implementing the air volume dynamic adjustment method of the grain storage ventilation system described in the embodiment, for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For relevant parts, refer to the partial description of the method, and details will not be repeated here.

Claims

1. A method for dynamically adjusting the air volume of a grain storage ventilation system, characterized in that, The grain storage ventilation system includes air valves for controlling the ventilation volume of corresponding grain pile partitions, and the method includes: Detecting the state parameters of each grain pile partition in real time, where the state parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the intake layer and the exhaust layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere; Calculating the state index of each grain pile partition in real time according to each state parameter, determining the corresponding target ventilation volume according to the state index, and dynamically adjusting the corresponding air valve to the target opening corresponding to the target ventilation volume; When ventilating the grain pile partition according to the target opening, calculating the ventilation wind speed in real time, calculating the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value based on the Penman-Monteith equation, and dynamically correcting the target ventilation volume according to the moisture evaporation rate.

2. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, The detection methods for the average temperature gradient of the grain layer, the average grain temperature, and the average grain temperature difference between the intake layer and the exhaust layer include: Setting up a temperature and humidity sensor matrix in the grain pile partition, and calculating the average temperature gradient of the grain layer, the average grain temperature, and the average grain temperature difference between the intake layer and the exhaust layer of the grain pile partition according to the temperature values detected by each temperature and humidity sensor in the temperature and humidity sensor matrix.

3. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, The detection methods for the absolute humidity of grain pile equilibrium desorption at the instant grain temperature and the absolute humidity of the instant atmosphere include: Determining the type of grain and the moisture content of the grain, and determining the absolute humidity of grain pile equilibrium desorption at the instant grain temperature according to the type of grain, the moisture content of the grain, and the average grain temperature based on the CAE equation or the equilibrium desorption absolute humidity curve graph; Detecting the water vapor density in the air in real time through an absolute humidity sensor to obtain the absolute humidity of the instant atmosphere.

4. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, The calculation formula for the state index is as follows: ； Among them, represents the state index, represents the average grain temperature, represents the average grain temperature difference between the intake layer and the exhaust layer, represents the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, represents the absolute humidity of the instant atmosphere, represents the average temperature gradient of the grain layer, and respectively represent the corresponding weights.

5. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, Determining the corresponding target ventilation volume according to the state index includes: Pre-constructing a first mapping relationship between the state index and the target ventilation volume in the test environment, and determining the target ventilation volume corresponding to the state index according to the first mapping relationship.

6. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, The calculation method for the ventilation wind speed includes: Determining the cross-sectional area of the grain pile in the grain pile partition, and detecting the actual ventilation volume of the grain pile partition at present, and calculating the ventilation wind speed according to the actual ventilation volume and the cross-sectional area of the grain pile.

7. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, The calculation formula for the moisture evaporation rate is as follows: ； Among them, represents the moisture evaporation rate, represents the slope of the saturation water vapor pressure - temperature curve, represents the net radiation, represents the internal heat conduction flux of the grain heap, represents the humidity constant, represents the average grain temperature, represents the ventilation wind speed, represents the saturation water vapor pressure, represents the actual water vapor pressure, represents the resistance coefficient of the grain heap.

8. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 1, characterized in that, Dynamically correcting the target ventilation volume according to the moisture evaporation rate includes: Determining a second mapping relationship between the moisture evaporation rate and the ventilation volume correction value in the experimental environment, determining the ventilation volume correction value corresponding to the moisture evaporation rate in real time according to the second mapping relationship, and dynamically correcting the target ventilation volume according to the ventilation volume correction value.

9. The method for dynamically adjusting the air volume of a grain storage ventilation system according to claim 2, characterized in that, The method further includes: Judging whether there is humidity abnormality or temperature abnormality according to the temperature values and humidity values detected by each temperature and humidity sensor in the temperature and humidity sensor matrix. If so, issuing a humidity warning or a temperature warning, and judging whether there is excessive moisture loss according to the moisture evaporation rate. If so, issuing an alarm for excessive moisture loss.

10. An apparatus for dynamically adjusting the air volume of a grain storage ventilation system, characterized in that, The grain storage ventilation system includes air valves for controlling the ventilation volume of corresponding grain pile partitions, and the device includes: A detection module for detecting the state parameters of each grain pile partition in real time, where the state parameters include the average temperature gradient of the grain layer, the average grain temperature, the average grain temperature difference between the air inlet layer and the exhaust air layer, the absolute humidity of grain pile equilibrium desorption at the instant grain temperature, and the absolute humidity of the instant atmosphere. A control module for calculating the state index of each grain pile partition in real time according to the state parameters, determining the corresponding target ventilation volume according to the state index, and dynamically adjusting the corresponding air valve to the target opening corresponding to the target ventilation volume; when ventilating the grain pile partition according to the target opening, calculating the ventilation wind speed in real time, calculating the moisture evaporation rate of the grain pile partition in real time according to the ventilation wind speed and the average grain temperature value and based on the Penman-Monteith equation, and dynamically correcting the target ventilation volume according to the moisture evaporation rate.

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