ISHS Acta Horticulturae 257: Energy Conservation and Solar Energy Utilization in Horticultural Engineering
A SYSTEM FOR DETERMINING PHOTOSYNTHETIC PHOTON FLUX DENSITY DISTRIBUTION OF LUMINAIRES |
| Authors: | P.N. Walker, S.Q. Turn |
| Abstract:
A facility was designed and constructed for testing luminaires which are used for supplemental greenhouse lighting, to determine their phosotynthetic photon flux density (PPFD) distribution patterns. In the facility, a microcomputer controls the movement of a luminaire and a quantum sensor, and collects and records data from the sensor. To demonstrate the use of this facility, a single luminaire was tested at a height of 1.5 m. Test data were analyzed and contour plots of PPFD were produced. PPFD distributions were then calculated for 2.0 m and 3.0 m luminaire spacing grids with a luminaire height of 1.5 m. The uniformity coefficient was determined and a contour plot of PPFD was made of a typical grid sector for each spacing. The 2.0 m spacing had an average PPFD of 90.5 μmol s-1 m-2 and a uniformity coefficient of 0.84; whereas for the 3.0 m spacing, these values were 40.2 and 0.75 respectively. | |
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