SE—Structures and Environment: Optimal Control Strategies for Carbon Dioxide Enrichment in Greenhouse Tomato Crops—Part 1: Using Pure Carbon Dioxide

✍ Scribed by Z.S. Chalabi; A. Biro; B.J. Bailey; D.P. Aikman; K.E. Cockshull

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 212 KB
• Volume: 81
• Category: Article
• ISSN: 1537-5110
• DOI: 10.1006/bioe.2001.0039

✦ Synopsis

Two optimal control strategies for carbon dioxide (CO ) enrichment in greenhouse tomato crops have been developed. One uses pure CO from a storage tank and the other uses CO contained in the exhaust gases of boilers burning natural gas. The optimal strategies maximize the "nancial margin between crop value and the combined costs of the CO used for enrichment and the natural gas used for heating. In this paper, the strategy for optimal control using pure CO is presented and compared with strategies used by growers. The optimal strategy for enrichment with exhaust gas derived CO is presented in an accompanying paper. Simulations show that at a cost of C0)09 kg\ for pure CO and C0)10 m\ for natural gas, the optimal enrichment strategy would increase the annual margin of crop value over CO and heating costs by C4)6 m\ (27%) compared to a basic control strategy of enrichment to a concentration of 1000 v.p.m. (parts per million by volume) when ventilators are (5% open, otherwise enrichment to 350 v.p.m. The optimal CO concentration was expressed as an algebraic function of solar radiation, wind speed and ventilator opening angle, and so enabled a quasioptimal value to be obtained using variables measured by greenhouse environmental controllers. The quasioptimal equation, with coe$cients averaged from simulations over 4 years, gave an increased margin over the basic control strategy of C4)4 m\ (26%).