Design of a wind tunnel for plug seedlings production under artificial lighting

摘要

A wind tunnel consisting of 2 air flow conditioners with polycarbonate pipes, a plant growth room, a suction fan and a fan controller, and fluorescent lamps, was designed to investigate the interactions between the growth of plug seedlings (plugs) under artificial light and their physical environment. Measurement showed a uniformity in the vertical profiles of air flow speed at the middle and rear regions of plug trays in the wind tunnel. Maximum air temperature was often observed near the top of astand of plugs. Since the Richardson number ranged from -0.07 to +0.01, the atmosphere over a stand of plugs in the wind tunnel was in an unstable or near-neutral stability state. Eddy diffusivity (Km) at an air speed of 0.9 m/s was _2 times as much asfor an air speed of 0.3 m/s. Km in the rear region was 1.6-23.1% lower than that in the middle region. The wind tunnel developed in this study would be useful to investigate the effects of air speed on the microclimates over and inside a stand of plugs and to collect basic data for large-scale plug production under artificial light in a semi-closed ecological system.