Design, construction, and testing of passive type solar tunnel for maize grain disinfestations

In this study, a solar tunnel of passive-type designed, constructed and tested for storage insect pest disinfestation. The designed solar tunnel was 1.9 m wide and 3 m long with the maize grain holding capacity of 150 kg, 300 kg, and 450 kg with 5 cm, 10 cm, and 15 cm layer thickness respectively. To evaluate the performance of the solar tunnel, maize grain infested with storage pests was kept in the solar tunnel with 5 cm, 10 cm, and 15 cm layer thickness for 4 consecutive days. During the study, the temperature and relative humidity profile of the air in the tunnel and the temperature in maize grain was recorded. Germination percentage and number of live insects were evaluated after each day of disinfestations. The highest temperature recorded in the solar tunnel was in the range of 64.6-67.6 °C during the study period. Complete disinfestations of the grain were obtained on the first day for 5 cm layer thickness and the second day for 10 and 15 cm layer thickness. The higher germination percentage was recorded for 15 cm layer thickness in all experimental days. Of all the treatments the combination of the layer thickness of 15 cm and two day disinfestations time were found to be the best combination for using the tunnel for maize grain disinfestations in terms of achieving complete disinfestations; maintaining germination capacity of the grain and time required to disinfect a large amount of grain.