Co-Authors:
Geoola, F., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Kashti, Y., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Peiper, U.M., Inst. of Agricultural Engineering, ARO, Volcani Center, PO Box 6, Bet Dagan 50250, Israel
Abstract:
An experimental model greenhouse for investigation of solar radiation transmission and aging of cladding materials in general, and of anti-drop materials in particular, was designed and constructed. The experimental greenhouse is supported by a turntable and can be turned to compensate for changes in surface azimuth angle of the sun rays, allowing nominal solar radiation transmissivity measurements at any season and any time of day. The experimental greenhouse which comprises eight identical sections was covered by four types of polycarbonate structured sheets. The sheets were tested for their transmissivity in a dry state and in a wet state (under condensation). In both states, the solar radiation transmissivity of the sheets under an accumulation of dust and dirt as a function of time was studied. The deterioration of surface-active additives in anti-drop sheets was studied. It is estimated that the experimental greenhouse accelerates the aging of surface-active additives in anti-drop cladding materials by a factor of three. © 1998 Silsoe Research Institute.