SOLAR HEATING OF GREENHOUSES IN CYPRUS

H. Bredenbeck
Within the scope of the GTZ/ARI project on "Solar greenhouse heating for vegetable production in Cyprus", two simple plastic film heat exchange systems have been installed in Nicosia and Zyghi. The system at Nicosia was operated with external in situ-made water collectors and plastic film heat exchangers used as heating surfaces inside the greenhouse. Below the heat exchangers channels of concrete tiles were made for the collection of water coming down from the heat exchangers. The channels also functioned as a heat store. The collector area was 0.33 m2/m2 greenhouse area, while the ratio of heating surface to ground area was 1:1. The storage volume was about 25 l/m2 of collector area. In the Zyghi system there were no external collectors, but a third sheet of black PE was placed between the two transparent layers of the heat exchanger in order to use them as collectors during the day time. Both systems were controlled by room and differential thermostats (see Figs. 1 and 2).

Compared with the previous years, the season 1984/85 had a relatively high heat demand. The calculated degree hours were 14,130 for 15°C, 9,400 for 13°C and 5,450 for 10°C set point temperature (Nicosia). There was a cold period in the beginning of December, followed by a relatively warm January. Mid February to the beginning of March brought a couple of cold, cloudy and windy days followed by clear nights with frost. During the first days of March the lowest temperatures of the season (2x -3; 4x -2) were recorded.

The requested degree hours at Zyghi were 10,700 and 9,050 for 15°C and 13°C respectively.

Bredenbeck, H. (1989). SOLAR HEATING OF GREENHOUSES IN CYPRUS. Acta Hortic. 257, 155-160
DOI: 10.17660/ActaHortic.1989.257.18
https://doi.org/10.17660/ActaHortic.1989.257.18

Acta Horticulturae