DETERMINATION OF DISTRIBUTION LEVELS OF DIFFERENT LED LIGHT SOURCES USED IN PHOTOSYNTHESIS IN THE GREENHOUSES
Project no. 1020 · Status: Kapanmış · 2016
Summary
In this study, it is aimed to determine the data of PAR distribution of different types of locally produced LED light sources which can be used in complementary lighting applications in greenhouses. Besides, it was also carried out within the scope of the study to determine the arrangements that could make the uniform PAR distribution and working efficiency in the LED light sources. In this context, four locally produced LED light sources developed for greenhouses were having been considered in the study. The PAR measurements were carried out within the specially designed testing unit in a dark room. The PAR measurement points in the testing unit consist of a total of 961 measurement points in the 10x10 cm square grid within the 3x3 m dimensions. The height between the PAR sensor and the LED light source was considered as 31.6, 50, 75, 100, 125 and 150 cm. In the evaluations, different uniformity coefficients were calculated and PAR distribution patterns were determined for a different arrangement. The minimum and maximum daily light integral values for A, B, C, and D type light sources for different hanging heights and considered spacings were determined as 23.8 – 9.3, 13.8 – 3.6, 2.1 – 1.3 and, 2.2 – 1.1 mol·m-2·day-1, respectively. In terms of daily light integral, it can be said that A and B type light sources can be used in both full artificial and supplementary lighting and, C and D light sources can be used only in supplementary lighting for PAR applications. It was determined that all LED light sources had acceptable PAR uniformity according to the different distribution uniformity evaluation criteria for 100, 125 and 150 cm hanging height and the considered spacings. Key word: LED, uniformity, energy efficiency, illuminance