Optimal CO2 enrichment strategy for greenhouses: a simulation study
Abstract
A model describing tomato seedlings in a commercial greenhouse is presented in detail. The model includes the following functions: (1) a "growth function", which relates the growth of the seedlings to the inside environmental conditions; (2) a "greenhouse function", which relates the inside conditions to the outside conditions and to the fluxes from the air-conditioning equipment; (3) an "equipment function", which relates the fluxes to the level of operation of the equipment, and (4) a "cost function", which evaluates the cost of operation. The model is used to optimize the operation of greenhouses according to a method presented previously, which requires the evaluation of certain optimal Lagrange multipliers. These are obtained for the growing of seedlings during the month of February in Israel. Three greenhouses, which differ from each other only in their CO2 enrichment capabilities, are examined. The greenhouse with CO2 supplied from bottles turns out to be superior to tthe greenhouse with CO2 supplied by burning gas. The latter system is economically superior to the system without enrichment. Some of the operation tables, which provide a recommended operation level for each set of outside conditions, are presented graphically for the three greenhouses. The results seem reasonable, but were not verified experimentally. © 1986.