Research On The Regulation Method Of Multi-Functional Solar Greenhouse Thermal-Humidity Environment Control System

Nowadays,people’s increasing demand for high-quality and diversified agricultural products and the rapid development of agricultural science and technology make modernized facility agriculture technology more and more important.To improve the level of automatic regulation and control of daylight greenhouses,overcome the problems of single regulation and control method,the untimely response of regulation signals,and inaccurate regulation targets in the production process of traditional daylight greenhouses,the paper proposes a multi-functional daylight greenhouse regulation system for the winter night weather environment characteristics and crop growing needs in northwest China.The paper proposes a multifunctional daylight greenhouse control system and designs a corresponding control strategy based on this system,combining the two to create a microclimate environment in terms of temperature control,humidity control,and airflow organization.The main research contents of this paper are as follows:By reviewing relevant literature to summarize the research of domestic and foreign scholars on the application of regulation equipment and the design and application of regulation strategies in sunlight greenhouses,and analyzing the gaps and shortcomings of research in this area,the analysis results show that there is less research on microclimate in greenhouses combining the functions of temperature control,humidity control,and airflow organization,and to address the gaps in this area,based on modern multifunctional sunlight greenhouses The design and validation of an environmental control strategy for the greenhouse based on a modern multifunctional heliostat is the main point of this paper.The main functional modules of the new heliostat control system proposed in this paper are introduced,including the active and passive phase change heat storage wall,the refrigerated dehumidifier for heliostat,and the uniform air supply system for heliostat keel,and the performance and geometric parameters of each module are explained through experiments and simulations.The heat transfer model of the multifunctional solar greenhouse was established and verified by grid independence,and the average absolute error was 1.29℃ when comparing the simulated values with the measured values.Based on the characteristics of temperature and humidity changes in the greenhouse and the specific needs of crop cultivation,this paper proposes three control strategies based on the multifunctional greenhouse environmental control system: a temperature threshold control strategy based on the indoor temperature value to determine the working condition,a humidity threshold control strategy based on the temperature value and relative humidity value,and a humidity prediction control strategy based on the change of temperature and relative humidity value to predict the working condition control strategy.Through a comparative analysis of the two groups of working conditions on cloudy days and sunny days,it was found that the difference between cloudy days and sunny days in terms of the indoor temperature change pattern and humidity change pattern to maintain the stability of the indoor temperature and humidity parameters required for the dehumidifier opening time is large,and the average indoor temperature under cloudy working conditions is 0.8℃-1.5℃lower than under sunny working conditions under the same regulation strategy and wind speed conditions,and the average indoor relative humidity is 0.8%-2%,the average energy consumption generated by the regulation is about 30% higher.The dehumidification effect was compared under four wind speeds,in which the highest dehumidification efficiency and the lowest overall energy consumption were achieved at a wind speed of 0.5 m/s.Its dehumidification efficiency was 15%-25% higher on sunny days compared with other wind speeds,and 25%-60% higher on cloudy days,and its indoor temperature was higher when the heat and humidity environment in the greenhouse reached dynamic equilibrium,and its maximum indoor temperature was 0.5℃-0.6℃ higher compared with other wind speeds.1.25m/s Although the indoor temperature and humidity values are more stable,its inlet and outlet backflow is obvious,dehumidification efficiency is low and the energy consumption is high.0.75m/s and 1m/s wind speed in the case of similar energy consumption,0.75m/s can make the average indoor temperature 0.5℃～1℃,so that the average indoor Relative humidity is 0.5%～2.6% lower,1m/s can keep the indoor hot and humid environment condition more stable,compared to other wind speed conditions,its length of time to stay in the temperature and humidity control range is about 20% higher.On cloudy days,we recommend using 1m/s wind speed under the temperature threshold control strategy,which has a higher energy efficiency ratio and can meet the needs of crop growth and development,while on sunny days,we recommend using 0.75m/s wind speed under the humidity threshold control strategy,which can create a better microclimate for the greenhouse while focusing on reducing the regulation energy consumption.If there is a higher demand for regulation of the indoor environment,it is appropriate to use the humidity prediction control strategy to regulate the indoor environment,under which 1m/s wind speed and 0.75m/s wind speed are recommended for sunny and cloudy days,respectively.