Determining thermal properties of canola pods as function of variety and times of harvest

Abstract

Canola pod thermal properties including thermal conductivity, specific heat, and thermal diffusivity in three common canola varieties (Hyola 420, Hyola 401, and Hyola 50) cultivated in the North of Iran at before-harvest, harvest, and post-harvest stages were measured. Thermal conductivity coefficient determined by line heat source, specific heat was determined through mixture method and thermal diffusivity was determined by calculation. The results showed that there was significant difference of thermal conductivity and specific heat between the three varieties, however, there was no significant difference of thermal diffusivity between these verities. Also, there was significant difference of thermal conductivity and specific heat between the three sampling time, however, there was no significant difference of thermal diffusivity between these sampling time. The results showed that there was significant difference of thermal conductivity, specific heat and thermal diffusivity between the interaction effects of variety and time. The thermal conductivity of Hyola 420 was significantly higher than that of Hyola 50 and Hyola 401 at pre-harvest and stage. However, the difference was not significant between the three varieties at both harvest and post-harvest stages. Thermal conductivity was significantly higher for pre-harvest stage than harvest and post-harvest stages for Hyola 50 and Hyola 420. However it was significantly higher for pre-harvest stage than harvest stage which in turn was significantly higher than post-harvest stage. Specific heat was significantly higher for Hyola 420 than Hyola 401 which in turn was significantly higher than Hyola 50 at pre-harvest and stage. The difference of specific heat was not significant between Hyola 420 and Hyola 401, however, Hyola 50 was significantly lower than that of Hyola 420 and Hyola 401 at harvest and stage. The difference was not significant between the three varieties at post-harvest stages. The difference was not significant between the three stages for Hyola 50. The difference of specific heat was not significant between pre-harvest and harvest for Hyola 401, however, post- harvest was significantly lower than that of pre-harvest and harvest stage. Specific heat was significantly higher for pre-harvest stage than harvest stage which in turn was significantly higher than post-harvest stage for Hyola 420. Thermal diffusivity was significantly higher for Hyola 420 than Hyola 50 which in turn was significantly higher than Hyola 401 at pre-harvest stage. The difference was not significant between the three varieties at harvest and post-harvest stages. Thermal diffusivity was significantly higher at harvest stage than post-harvest stage which in turn was significantly higher than pre-harvest stage for Hyola 50. And, it was significantly higher at post-harvest stage than harvest stage which in turn was significantly higher than pre-harvest stage for Hyola 401. The difference was not significant between the three stages for Hyola 420. The results are usable in thermal properties modeling and also prediction of the value of the properties. Also the results are relevant and applicable for drying before threshing used in farm dryer unit and reducing seed losses at canola harvest.