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A technical feasibility study on the use of Çavundur geothermal field for greenhouse heating

Kasapoğlu, Hüseyin
Protective cultivation is widely used nowadays in order to increase crop yield by creating the optimum conditions such as temperature, humidity and CO2 content, irrespective of outside conditions. Since plant production doubles for every 10 degrees increase in temperature to a certain limit, this makes temperature a very important factor for optimum plant growth. In order to keep the greenhouse temperature constant during changes in outside conditions, heating and often cooling are required. Heating of a greenhouse can be done using different systems and design procedures. The applicability of different types of greenhouses is studied at the field local conditions, Çavundur-Çankiri, Turkey. Required heating load was calculated that is due to infiltration and conduction through the greenhouse cover at a single design point, which is the minimum outside temperature. Two types of heating systems, soil heating system and bare tube system, were considered. Analysis of results showed that, Çavundur geothermal field with 54 °C fluid temperature is suitable for greenhouse heating. Although the existing well Ç-1 is capable of producing 47 l/s, the flow rate of geothermal fluid for greenhouse heating was limited by 35 l/s due to existing thermal facilities in the area. Among different glazing materials, plastic film covered greenhouses with double poly was found to be the most suitable in terms of heat load calculations. The maximum number of greenhouses (the area of each green house is 216 m2) that can be heated by Çavundur Geothermal field was found to be 138 by considering soil heating with double poly glazing material. Annual heat load factor of geothermal energy for greenhouse heating in Çavundur area was found to be as high as 96% depending on indoor design temperature and base load.