A MODEL OF GREENHOUSE HUMIDITY SUITABLE FOR CONTROL OF CROP PROCESSES

摘要

A physical model of humidity within a greenhouse was developed, whereby ambient vapour concentration resulted from the balance of three fluxes: crop transpiration, ventilation and condensation at the cover. The present paper describes the applicationof such a model in the greenhouse climate control. Two examples are shown in order to demonstrate that it is possible to deduce set points for climate actuators from desired levels of humidity-related crop processes such as transpiration or dew forming.Within the selected range, the final choice of set points can be based on cost-benefit analysis. This could prevent useless ventilation and heating and consequently save energy. Accordingly, modern greenhouse climate management could be largely improvedby incorporating physical models in order to deduce set points for actuators (mainly temperature and ventilation) directly from the desired level of a crop process.