تحليل عوامل و الزامات نوين تجديد ساختار سازماني ترويج كشاورزي ايران

Investigation of temperature and humidity variations within a greenhouse using a computer-based data acquisition system

In order to control greenhouse environment, a computer-based control and monitoring system was designed and implemented. Performance of the system was evaluated by installing it in a constructed model greenhouse.The greenhouse has a floor area of 8m2, covered with 200 ?m polyethylene film.The set of experiments were carried out during December 2003 in the city of Karaj.The simulation results achieved for the air temperature and relative humidity are shown. The results indicate that the outside temperature is always less than the inside one, because the solar radiation entered the greenhouse through transparent plastic.This is a further confirmation of greenhouse effect.The fluctuations in temperature inside the model greenhouse during observation time were recorded.These fluctuations were affected by natural conditions such as surface evaporation within the greenhouse, solar radiation and ambient temperature and weather changes. Also, it was found that the rate of change of temperature in the upper part, i.e. near the plastic cover, is higher than that of the height of plants. This rise of vertical temperature is due to receiving solar incident radiation.