Development of Efficient Solar Heaters for Storage Insect Pest Management

Two designs of solar heaters, obtuse-base-angle box and square box, were evaluated for solar energy trapping efficiency using adzuki bean as test crop. The angle box had three base-angles and glued with either copper shim or aluminum foil from inside. The latter had three box heights with black painting either from inside or outside. Then adzuki bean seed, infested with Callosobruchus maculatus , was heat treated at 1, 2, 3 and 4 cm seed layer thickness in 118° base-angle aluminum foil glued box heater. Maximum within-seed temperature of 80.7°C was obtained in the aluminum foil glued heaters; the 118° base-angle heater having high performance. For the square box heaters, the maximum within-seed temperature of 73.5° C was evident in those painted black from inside with better performance of boxes with 10 cm height. Square boxes painted black from outside were not as efficient. Heating of up to 3 cm adzuki bean seed layer resulted in complete C. maculatus control. Thus, obtuse-base-angle box heater glued with aluminum foil from inside could be a potential solar heater for storage pest control by optimizing base angle and size of the box