The closed environment of greenhouses will cause the carbon dioxide concentration in the greenhouse to be insufficient, affecting the growth and development of crops. In order to be able to use the modern electronic equipment to measure and control the carbon dioxide concentration according to the growth demand of the crop, the concentration of carbon dioxide is controlled in the best state to ensure the growth and development of the crop.
The single-chip microcomputer of carbon dioxide measures the information of temperature, carbon dioxide concentration and sunshine intensity in the greenhouse through temperature sensor, carbon dioxide concentration measurer and illuminance sensor, and then calculates the concentration of carbon dioxide needed by the plant according to the species and date of the plant. The carbon dioxide concentration is controlled. There are two independent control systems for temperature and carbon dioxide concentration in this control. The temperature control system is used to measure the concentration of carbon dioxide. The single-chip output pulse signal with adjustable pulse width triggers the zero-crossing thyristor and provides 0~220V AC to control the temperature. The temperature is stabilized in the range of 25 to 1e to ensure the CO2 concentration. The correctness of the measurement.
The carbon dioxide meter is based on information such as the crop type entered by the user through the panel, the date the crop was sown, and so on. The SCM calculated the carbon dioxide concentration control scheme according to the crop variety, the crop growth period, the current season, the temperature in the greenhouse, and the illuminance, and added two proportional liquids through a dilute sulfuric acid feeder and an ammonium bicarbonate feeder. Chemical reaction produces carbon dioxide gas, which diffuses carbon dioxide gas into the greenhouse under the action of a blower. When the concentration of carbon dioxide reaches the specified value, the reaction is stopped, and the solenoid valve is controlled to let go of the remaining material of the reaction and prepare for the next reaction.
Usually under certain light and temperature conditions, the photosynthetic rate of crops increases with the increase of carbon dioxide concentration. When the concentration of carbon dioxide increases to a certain degree, the photosynthetic rate of crops does not increase any longer. At this time, the concentration of carbon dioxide is called photosynthetic rate. Carbon dioxide saturation point. Conversely, when the concentration of carbon dioxide is reduced to a certain level, the photosynthetic rate of the crop is zero, and the organic matter produced by the photosynthesis of the crop is equal to the substance consumed by its respiration. The concentration of carbon dioxide at this time is called the compensation point for photosynthesis. The photosynthetic performance of different crops is different. Generally, the saturation point of carbon dioxide in fruits and vegetables is 1.0-2.0 mL/L, and the saturation point of carbon dioxide in leafy vegetables is 0.6-1.0 mL/L. Their compensation point is about 0.1 mL/L. . In addition, the carbon dioxide concentration of the same crop in different growth periods also has different needs; different seasons and temperature crops also have different photosynthesis. Therefore, in the CO2 concentration control software, data on the CO2 concentration demand of various crops at different temperatures, seasons, and growth periods are stored. Based on these data and the detection of greenhouse environmental conditions, the control software calculates the current required carbon dioxide concentration in the greenhouse, uses it as a set point for the control system, and uses the carbon dioxide concentration in the current greenhouse as a feedback value.
The carbon dioxide meter control system calculates the addition amount of dilute sulfuric acid and ammonium bicarbonate based on the difference between the two values ​​to perform a chemical reaction and achieve the purpose of control. Since the volume of greenhouses is around 200-500 m3, and the change of the concentration of carbon dioxide in the greenhouse takes a long time to reach equilibrium, after a liquid chemical reaction, it takes some time to wait for measurement and control. The waiting time is related to the volume of the greenhouse. When the user is in use, the volume of the greenhouse can be input through the operation panel. The microcontroller will determine the waiting time according to the size of the greenhouse. The automatic control of the carbon dioxide concentration in the greenhouse is different from the general single-loop PID automatic control, but it is an intelligent control based on logical discrimination.
Carbon dioxide meter is a device with low price and suitable for China's rural needs. Monitoring the carbon dioxide concentration in greenhouses can not be ignored for the growth and development of crops. China has a vast area and a wide range of climatic conditions. The same control software is not universal. Therefore, it needs a lot of applications and improvements to be more complete and practical.
The single-chip microcomputer of carbon dioxide measures the information of temperature, carbon dioxide concentration and sunshine intensity in the greenhouse through temperature sensor, carbon dioxide concentration measurer and illuminance sensor, and then calculates the concentration of carbon dioxide needed by the plant according to the species and date of the plant. The carbon dioxide concentration is controlled. There are two independent control systems for temperature and carbon dioxide concentration in this control. The temperature control system is used to measure the concentration of carbon dioxide. The single-chip output pulse signal with adjustable pulse width triggers the zero-crossing thyristor and provides 0~220V AC to control the temperature. The temperature is stabilized in the range of 25 to 1e to ensure the CO2 concentration. The correctness of the measurement.
The carbon dioxide meter is based on information such as the crop type entered by the user through the panel, the date the crop was sown, and so on. The SCM calculated the carbon dioxide concentration control scheme according to the crop variety, the crop growth period, the current season, the temperature in the greenhouse, and the illuminance, and added two proportional liquids through a dilute sulfuric acid feeder and an ammonium bicarbonate feeder. Chemical reaction produces carbon dioxide gas, which diffuses carbon dioxide gas into the greenhouse under the action of a blower. When the concentration of carbon dioxide reaches the specified value, the reaction is stopped, and the solenoid valve is controlled to let go of the remaining material of the reaction and prepare for the next reaction.
Usually under certain light and temperature conditions, the photosynthetic rate of crops increases with the increase of carbon dioxide concentration. When the concentration of carbon dioxide increases to a certain degree, the photosynthetic rate of crops does not increase any longer. At this time, the concentration of carbon dioxide is called photosynthetic rate. Carbon dioxide saturation point. Conversely, when the concentration of carbon dioxide is reduced to a certain level, the photosynthetic rate of the crop is zero, and the organic matter produced by the photosynthesis of the crop is equal to the substance consumed by its respiration. The concentration of carbon dioxide at this time is called the compensation point for photosynthesis. The photosynthetic performance of different crops is different. Generally, the saturation point of carbon dioxide in fruits and vegetables is 1.0-2.0 mL/L, and the saturation point of carbon dioxide in leafy vegetables is 0.6-1.0 mL/L. Their compensation point is about 0.1 mL/L. . In addition, the carbon dioxide concentration of the same crop in different growth periods also has different needs; different seasons and temperature crops also have different photosynthesis. Therefore, in the CO2 concentration control software, data on the CO2 concentration demand of various crops at different temperatures, seasons, and growth periods are stored. Based on these data and the detection of greenhouse environmental conditions, the control software calculates the current required carbon dioxide concentration in the greenhouse, uses it as a set point for the control system, and uses the carbon dioxide concentration in the current greenhouse as a feedback value.
The carbon dioxide meter control system calculates the addition amount of dilute sulfuric acid and ammonium bicarbonate based on the difference between the two values ​​to perform a chemical reaction and achieve the purpose of control. Since the volume of greenhouses is around 200-500 m3, and the change of the concentration of carbon dioxide in the greenhouse takes a long time to reach equilibrium, after a liquid chemical reaction, it takes some time to wait for measurement and control. The waiting time is related to the volume of the greenhouse. When the user is in use, the volume of the greenhouse can be input through the operation panel. The microcontroller will determine the waiting time according to the size of the greenhouse. The automatic control of the carbon dioxide concentration in the greenhouse is different from the general single-loop PID automatic control, but it is an intelligent control based on logical discrimination.
Carbon dioxide meter is a device with low price and suitable for China's rural needs. Monitoring the carbon dioxide concentration in greenhouses can not be ignored for the growth and development of crops. China has a vast area and a wide range of climatic conditions. The same control software is not universal. Therefore, it needs a lot of applications and improvements to be more complete and practical.
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