Use of flat plate solar collectors and parabolic trough concentrators for greenhouse soil disinfestation

Abstract

The aim of the present work was to investigate the use of low and medium temperature active solar energy systems for the disinfestation of greenhouse soils. Four flat plate solar collectors (low-temperature solar thermal energy devices) and six parabolic trough concentrators (medium-temperature solar thermal energy devices) were used to heat water, which, via a buried heat exchange system, was used to heat the soil of greenhouse plots. These treatments were compared to no solar (control) and solarized (using a 50 micro m-thick transparent polyethylene sheet) plots. Experiments performed in the summers of 2004 and 2005 showed that: 1) the temperatures reached and the energy accumulated in the soil - and therefore the disinfestation capacity - were greater with either of the active solar treatments (40-60 deg C and 10.222.438-18.102.054 J, respectively) than with solarization (< 40 deg C and 6.628.760 J, respectively) and 2) the temperatures reached using the parabolic trough concentrators (50-60 deg C) were higher than those achieved with the flat plate solar collectors (40-50 deg C). The soil temperatures reached suggest these systems could be used to disinfest greenhouse soils.