DEVELOPMENT OF SIMPLE SYSTEMS FOR DISTRIBUTION OF GEOTHERMAL ENERGY IN GREENHOUSES

M. Grafiadellis
After the 1973 oil shock and the rapid increase in price of primary energy, considerable effort has been given in Agricultural Research Center of Northern Greece to find simple and economical ways of using geothermal energy for heating greenhouses.

In the beginning some of the solar systems developed were used to distribute geothermal energy in greenhouses as well. Later on special more effective and low cost systems for distribution of geothermal energy in greenhouses have been developed. The reason of going towards simple systems was to overcome the high cost needed for the distribution of geothermal energy in greenhouses.

The most interesting systems for distribution of geothermal energy in greenhouses developed in Agricultural Research Center of Northern Greece are the following:

The first system consists of a fan, a water pump and two plastic tubes through which water and air are circulating simultaneously. Air from the greenhouses is heated with the warm water.

The second system is also an air-water plastic heat exchanger and the main parts of which are a heat exchanger, a fan and a water pump. With this system air from the greenhouse is heated as it comes in contact with the warm water through a plastic sheet.

In the third system heat distribution in greenhouses is obtained by the circulation of warm water in transparent polyethylene tubes laid on the soil among plant rows.

In the fourth system heat distribution in greenhouses is done by a simple water-air plastic heat exchanger, where water is circulating in transparent polyethylene tubes and air is blowing through a bigger plastic tube.

From the research done it is found that the third system is the simplest, the most effective in the increase of air temperature and the more economical one.

Grafiadellis, M. (1990). DEVELOPMENT OF SIMPLE SYSTEMS FOR DISTRIBUTION OF GEOTHERMAL ENERGY IN GREENHOUSES. Acta Hortic. 263, 375-382
DOI: 10.17660/ActaHortic.1990.263.37
https://doi.org/10.17660/ActaHortic.1990.263.37

Acta Horticulturae