A RESEARCH ON VENTILATION EFFICIENCY OF PIPED VENTILATION SYSTEMS IN GEOTHERMALLY HEATED GREENHOUSES

Greenhouse play significant roles in human nutrition. Vegetable and fruit consumption at certain amounts is the basic pre-condition for a well nutrition. It is possible to produce sufficient quantities of fruits and vegetables in places with available climate conditions. However, fruits and vegetables should be grown in special buildings to have a year-long production in places without available climate conditions. These places include under-cover production facilities, greenhouses, low and high tunnel facilities. Environmental conditions are adjusted are adjusted in greenhouses as to provide proper conditions for plant growth and development. Ventilation is used to remove excess heat, moisture and carbon dioxide from the greenhouses. Either natural or mechanical ventilation is used in greenhouses. Mechanical ventilation systems have various advantages over natural systems. However, mostly natural ventilation systems are preferred because of their low installation and operational costs. Both systems operates based on negative pressure. Air exchange rates are usually low in winters and it is quite hard to evenly distribute cold fresh air within the greenhouse. Air inlets are usually placed over side walls and outlets are commonly placed along the ridge. In this study an alternative natural ventilation system was proposed for more efficient ventilation of the greenhouses. In this system, fresh air gets into the greenhouse through ventilation pipes installed beneath the greenhouse floor. The incoming fresh air also heated with geothermal hot water lines, thus direct contact of cold fresh air is prevented. The design and efficiency of piped ventilation systems were provided in this paper