Abstract:
With the workmanship decrease in farms, the necessity to rationalize the use of other inputs and the development of
technology has rapidly expanded the use of computer simulation in agricultural systems. One of the agricultural systems
in which the modeling process of plant growth has been more engaged is the greenhouse production for horticultural
crops. In Mediterranean climate, it is during the night that the energy losses are important and can be compensated with
an artificial heat input. In this work an experiment was performed in a greenhouse in the north of Portugal. Temperature
values in several points and air velocity in the aperture were measured during the night for three different cases: natural
convective heating (case A); artificial heating tubes (AHT) (case B); AHT and natural ventilation (case C). A CFD
simulation, carried out using FLOTRAN module of ANSYS, was also performed in two-dimensional configuration to
obtain the indoor air temperature and velocity fields for the three cases. A very good agreement between experimental
and numerical temperature values were verified, which allows to validate the adopted numerical procedure. In case A,
the average temperature was 2.2˚C. An average increase of 6.7˚C and 3.5˚C on the air temperature was obtained for the
case B and case C, respectively. These results clearly emphasis the influence of each thermal load on greenhouse indoor
air properties
