Robust climate control of a greenhouse equipped with variable-speed fans and a variable-pressure fogging system

Raphael Linker, Murat Kacira, Avraham Arbel

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

A climate control system for a small greenhouse equipped with a variable-pressure fogging system and variable-speed extracting fans was developed and validated. The controllers were designed using the robust control method quantitative feedback theory (QFT) that guarantees adequate performance of the controlled system despite large modelling uncertainties and disturbances. In order to simplify the design of the controllers and achieve better performances, partial decoupling between the two control loops was achieved by describing the greenhouse climate in terms of air enthalpy and humidity ratio. This led to using ventilation for achieving the desired air enthalpy, and fogging for achieving the desired humidity ratio, assuming that the ventilation rate was approximately known. The implementation results demonstrated the good performance of the controllers, with mean tracking errors of ~100 J kg-1 [dry air] and ~0.1 g [water] kg-1 [dry air] for enthalpy and humidity ratio, respectively. For practical applications, the desired climate was expressed in terms of air temperature and relative humidity, which were converted into enthalpy and humidity ratio using the psychrometric relationships. In this case, the mean tracking errors were ~0.2 °C air temperature and less than 1% relative humidity, and the maximum mean deviations over a 10-min period with constant setpoints were 2.5 °C air temperature and 5% relative humidity.

Original languageEnglish (US)
Pages (from-to)153-167
Number of pages15
JournalBiosystems Engineering
Volume110
Issue number2
DOIs
StatePublished - Oct 2011

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Climate control
Air Conditioning
Greenhouses
fans (equipment)
enthalpy
Humidity
Fans
humidity
Atmospheric humidity
controllers
Air
greenhouses
climate
Pressure
relative humidity
air
air temperature
Enthalpy
ventilation
environmental control systems

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Food Science
  • Animal Science and Zoology
  • Soil Science
  • Control and Systems Engineering

Cite this

Robust climate control of a greenhouse equipped with variable-speed fans and a variable-pressure fogging system. / Linker, Raphael; Kacira, Murat; Arbel, Avraham.

In: Biosystems Engineering, Vol. 110, No. 2, 10.2011, p. 153-167.

Research output: Contribution to journalArticle

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