Simulation of fixed and variable fogging rates in a naturally ventilated greenhouse: Water and energy savings and stability of climate

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Simulation of fixed and variable fogging rates in a naturally ventilated greenhouse: Water and energy savings and stability of climate

Year: 

2012

Source of publication :

Acta Horticulturae

Authors :

Arbel, Avraham

.

Volume :

952

Co-Authors: 

Villarreal-Guerrero, F., Agricultural and Biosystems Engineering, University of Arizona, Tucson, AZ, United States
Kacira, M., Agricultural and Biosystems Engineering, University of Arizona, Tucson, AZ, United States
Fitz-Rodríguez, E., Agricultural and Biosystems Engineering, University of Arizona, Tucson, AZ, United States
Giacomelli, G.A., Agricultural and Biosystems Engineering, University of Arizona, Tucson, AZ, United States
Linker, R., Israel Institute of Technology, Haifa, Israel
Kubota, C., School of Plant Sciences, University of Arizona, Tucson, AZ, United States
Arbel, A., Agricultural Research Organization, Bet-Dagan, Israel

From page: 

37

To page: 

44

(

Total pages: 

8

)

Link :

Simulation of fixed and variable fogging rates in a naturally ventilated greenhouse: Water and energy savings and stability of climate

Abstract: 

Cooling must be supplied for greenhouses located in semiarid climates most of the year to provide desired climate conditions for year-round crop production. High-pressure fogging systems have shown promising results for cooling, however the lack of effective control strategies, especially under passive ventilation, have limited their use. In this study, a new proposed climate control strategy, which considers the contribution on cooling and humidification from plants, is tested through simulation. The developed strategy using variable pressure fogging (VPF) and variable vent configurations was compared to a constant pressure fogging (CPF), fixed vents cooling strategy. In both cases, the control of fog was based on vapor pressure deficit (VPD) set points. Results showed that on average, VPF based system was able to save 15.2% of water and consumed 10.1% less energy. Pump cycling was reduced by 78.5% and lower temperature and relative humidity fluctuations were achieved by adjusting fog rates through manipulating the system working pressure. Finally, simulations also showed that by reducing the number of nozzles, a smaller fogging rate was achieved and the system performance and savings on water and energy were enhanced during morning hours of operation.