ISHS Acta Horticulturae 154: II International Symposium on Plastics in Mediterranean Countries
DEVELOPMENT OF SOLAR SYSTEMS FOR HEATING GREENHOUSES |
| Author: | M. Grafiadellis |
| Abstract:
The energy crisis of 1973 and the consequent increase in price of the primary energy necessitated the development of simple and effective ways for greenhouse heating at the Agricultural Research Center of Northern Greece. In this context, the following solar systems were developed, consisting of: 1st system: An external plastics solar collector and an underground water reservoir connected with plastics tubes for water circulation. 2nd system: An underground water reservoir, a fan, a water pump and two plastic tubes for simultaneous circulation of water and air. 3rd system: An air/water plastics heat exchanger, a water reservoir, a fan and a pump, the water being heated in day time from the air while at night the process is reversed. 4th system: Water is sprayed on the top of the greenhouse, while simultaneously air is circulating in the greenhouse to absorb heat from the sprayed water and from the soil. Finally the fifth system makes use of the greenhouse soil as a means of heat storage. During the colder hours of the day, air is circulating inside the greenhouse and is absorbing heat from the soil. It was found that a clear night, when the air temperature in a nonheated greenhouse was 0°C, the air temperature in greenhouse heated with the aforementioned solar systems was as follows: first solar system 5–7°C, second 8°C, third 5–6°C, fourth 8°C and fifth 2–3°C. | |
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