GREENHOUSE HEATING SYSTEMS WITH GEOTHERMAL ENERGY OF LOW ENTHALPY IN GREECE
The heating systems were applied in three experimental greenhouses with arch profil in Eleochoria of Chalkidiki (N. Greece). A fourth greenhouse of the same type used as "control plot" was heated by conventional fuels. The first system includes a greenhouse with double wall of polyethylene cover and the water is sprayed in the space between the outer and the inner plastic wall. The second system is installed in a greenhouse of a single polyethylene cover and it is based on forced convection of heat from the water with the use of a specially constructed air heater. The third system is installed in a greenhouse alike the previous one and it consists of four black corrugated polypropylene pipes placed on the ground along each plant row.
The results of this work seem to be very promissing. During two winter periods the heat energy produced by each system was sufficient to cover the heat requirements of the tomato plants successfully. As a result, a satisfactory amount of tomatoes was produced.