Development and test verification of air temperature model for Chinese solar and Spainish Almeria-type greenhouses

Growth can be defined as an increment in biomass or an increment in weight or height of the organs of the plant influenced by physiological processes.Many of these processes have their limits genetically determined,but climate and irrigation play an important role.Because of its importance,microclimate has been extensively studied in the modeling as a surrounding condition which is imposed by the exterior climate.The main objective of this work was to develop a temperature model based on the energy balance dynamics at two different greenhouse locations-South-eastern Spain and Northern China,and the traditional structures of Chinese solar greenhouse and Almería-type multi-span greenhouse were taken into account.The final model was developed by combining the external conditions,the actuator influence and the crop growth,where the temperature is influenced by soil,crop,cover,actuators,back wall and greenhouse geometry.The model took into account the energy lost by convective and conductive fluxes,as well as the energy supplied by solar radiation and heating systems.The soil and the back wall are the main media for energy storage.The temperature dynamic was determined by a physical model,which considered the energy balance from a holistic point of view-as a sub-model for a customizable interface among the external climate,the plant and the greenhouse system.The influences of different subsystems included in the temperature model were analyzed and evaluated.The results showed a high R^(2)value of 0.94 for Beijing and 0.95 for Almeria,and the average error was low,of which the MAE and RMSE were 0.71 and 1.365 for Almeria and 0.62 and 1.102 for Beijing,respectively.Thus,the model can be considered as a powerful tool for control design purposes in microclimate systems.

Analysis of solar radiation changes in Chinese solar greenhouses with different roof structures based on a solar radiation model

Chinese solar greenhouses(CSGs)are important agricultural production facilities.Under non-artificial heating conditions,solar radiation is the only CSGs energy source.It is highly important to optimally obtain solar energy in greenhouse construction and production.In this study,a solar radiation model for solar greenhouses was adopted to explore the quantities of solar radiation in greenhouses considering different front roof forms and angles.Herein,the solar radiation amounts corresponding to five roof forms,namely,double-section arc,parabolic,oval,arc,and linear roofs,are compared and analyzed during the four solar periods(beginning of spring,vernal equinox,beginning of winter,and winter solstice).It was found that the solar radiation of oval roof greenhouses on the ground was the largest and was 4.44%-23.68%higher than that of parabolic roofs.In addition,the cumulative sum of light on the linear roof greenhouse wall is also the largest and was 6.02%to 12.08%higher than the parabolic roof greenhouse in the four solar terms.Moreover,the solar radiation in CSGs was compared with front roof angles of 25°,30°,and 35°.It was observed that the solar radiation amount gradually increases with increasing angles.Notably,the variation at an angle of 35°influences the solar radiation of the paraboloidal CSGs ground and elliptical CSGs north wall to the greatest extent,which increased by 8.23%and 12.74%,respectively.This study confirms the role of front roof form and inclination angle in enhancing the greenhouse solar radiation level.