ISHS Acta Horticulturae 614: VI International Symposium on Protected Cultivation in Mild Winter Climate: Product and Process Innovation
VALIDATION OF A RADIATION TRANSMISSION MODEL FOR ASYMMETRICAL GREENHOUSES |
| Authors: | T. Soriano, M.I. Morales, N. Castilla, J. Hernández |
| Keywords: | Direct radiation, multispan, scale model, greenhouse orientation, transmissivity |
| Abstract:
The prevailing solar radiation in autumn and winter associated with the large number of clear days, one of the advantages of the Mediterranean climate for protected cultivation, is partly offset by the limited radiation transmission of low-cost Mediterranean greenhouses. Light transmission enhancement has been remarked as a prevailing objective to rise the quality and quantity of the production. A direct solar radiation transmission simulation model for asymmetrical saddle roof greenhouses was developed and validated, using scale model greenhouses. Solar radiation transmission in the scale models was quantified using linear solarimeters, that integrated solar radiation along the transversal section of the span. Simulation and measured transmission data correlated well for hourly and daily average transmission values. Measured transmission on the scale models was slightly lower than simulation data, influenced by the atmospheric conditions (turbidity, diffuse radiation, ...), dust accumulation and water condensation. Measurements in the scale models show that radiation transmission values quantified in singlespan greenhouses are different from those measured in multispans of the same roof geometry. East-west orientation rises transmission as compared with north-south orientation, when the sun elevation is low in our latitude (37ºN). Increasing the roof slope of the southern side in these east-west oriented asymmetrical greenhouses increases the radiation transmission in autumn and winter, relative to low roof slope conventional greenhouses. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
