Natural ventilation is one of the more simple and efficient way for the conditioning of greenhouse internal microclimate; it may contribute to decrease levels of energy consumption and CO2 emission and it may reveal. if adequately managed, as a very useful tool for the control of temperature. relative humidity and CO2 concentration of inside air. One of its limitations is the spatial distribution of air temperature and humidity, strictly linked to outside conditions, particularly wind speed and direction. In order to contribute to the analysis of conditions for an optimal control of natural ventilation, experimental tests were carried out in a vaulted steel-constructed greenhouse, where soilless Lily flower plants were cultivated, naturally ventilated through two sidewall ventilators and/or two ridge ventilators. The measurements of the airflow inside the greenhouse were carried out by means of a three-dimensional sonic anemometer, detecting both the spatial components of the air velocity and the air temperature in several different internal points inside the greenhouse. For each position three different opening strategies were analysed, i.e.: i) sidewall ventilators only; ii) ridge ventilators only and iii) both sidewall and ridge ventilators opened. Wind direction and velocity, together with outside air temperature, were also measured, and data were collected and analysed in order to calculate the parameters describing the turbulence. Moreover, the Fast Fourier Transform (FFT) was applied on the set of measured data in order to evaluate the power spectra of the air velocity vector components for the different configurations. From the obtained results it was possible to examine the influence of external wind on the distribution of air velocity components of internal airspace, so contributing to the knowledge of the transient response of the greenhouse to the variation of external wind; moreover, the airflow inside the greenhouse and the turbulence parameters gave indications useful for a more specific implementation in an algorithm suitable for the automated control of the natural ventilation system.
Natural ventilation as a management tool for the optimisation of greenhouse operation control
VOX, Giuliano;SCARASCIA MUGNOZZA, Giacomo;
2003-01-01
Abstract
Natural ventilation is one of the more simple and efficient way for the conditioning of greenhouse internal microclimate; it may contribute to decrease levels of energy consumption and CO2 emission and it may reveal. if adequately managed, as a very useful tool for the control of temperature. relative humidity and CO2 concentration of inside air. One of its limitations is the spatial distribution of air temperature and humidity, strictly linked to outside conditions, particularly wind speed and direction. In order to contribute to the analysis of conditions for an optimal control of natural ventilation, experimental tests were carried out in a vaulted steel-constructed greenhouse, where soilless Lily flower plants were cultivated, naturally ventilated through two sidewall ventilators and/or two ridge ventilators. The measurements of the airflow inside the greenhouse were carried out by means of a three-dimensional sonic anemometer, detecting both the spatial components of the air velocity and the air temperature in several different internal points inside the greenhouse. For each position three different opening strategies were analysed, i.e.: i) sidewall ventilators only; ii) ridge ventilators only and iii) both sidewall and ridge ventilators opened. Wind direction and velocity, together with outside air temperature, were also measured, and data were collected and analysed in order to calculate the parameters describing the turbulence. Moreover, the Fast Fourier Transform (FFT) was applied on the set of measured data in order to evaluate the power spectra of the air velocity vector components for the different configurations. From the obtained results it was possible to examine the influence of external wind on the distribution of air velocity components of internal airspace, so contributing to the knowledge of the transient response of the greenhouse to the variation of external wind; moreover, the airflow inside the greenhouse and the turbulence parameters gave indications useful for a more specific implementation in an algorithm suitable for the automated control of the natural ventilation system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
