Performance and energy costs associated with scaling infrared heater arrays for warming field plots from 1 to 100 m

Abstract

To study the likely effects of global warming on open-field vegetation, hexagonal arrays of infrared heaters are currently being used for low-stature (<1 m) plants in small (≤3 m) plots. To address larger ecosystem scales, herein we show that excellent uniformity of the warming can be achieved using nested hexagonal and rectangular arrays. Energy costs depend on the overall efficiency (useable infrared energy on the plot per electrical energy in), which varies with the radiometric efficiency (infrared radiation out per electrical energy in) of the individual heaters and with the geometric efficiency (fraction of thermal radiation that falls on useable plot area) associated with the arrangement of the heaters in an array. Overall efficiency would be about 26% at 4 ms −1 wind speed for a single hexagonal array over a 3-m-diameter plot and 67% for a 199-hexagon honeycomb array over a 100-m-diameter plot, thereby resulting in an economy of scale.