Encontro de Energia no Meio Rural
Agrener

Abstract

GALVANI, Emerson, ESCOBEDO, João Francisco and AGUIAR E SILVA, Marcelo A. de. Estimativa da irradiação difusa em estufas de polietileno nas orientações leste-oeste e norte-sul. In Proceedings of the 3. Encontro de Energia no Meio Rural, 2000, Campinas (SP, Brazil) [online]. 2003 [cited 25 April 2024]. Available from: <http://www.proceedings.scielo.br/scielo.php?script=sci_arttext&pid=MSC0000000022000000200057&lng=en&nrm=iso> .

In this work is shown simple linear equations to estimate daily diffuse radiation inside and outside of two polyethylene (100 mm of thickness) tunnel greenhouses, oriented at East-West and North-South direction. During the year of 1996 diffuse irradiance (W.m^-2) were measured using an Eppley-PSP piranometer, shaded by a ring. Irradiance values were integrated to find the daily values of diffuse radiation. It was found that, for relatively high values of diffuse outside the greenhouse, the corresponding inside values were always lower while the converse occurred when the outside values were relatively low. Is was concluded that, under the climatic conditions of Botucatu/SP-Brazil and for greenhouse with characteristics similar to those used in this experiment, monthly average daily diffuse radiation inside the greenhouse were not dependent on the greenhouse orientation but a function of the sky condition. It was also concluded that a simple linear equation can be used, with good accuracy, in the estimation of daily diffuse radiation inside de greenhouse from measurements taken outside.

Keywords : irradiância difusa; estufas; modelos.