Thermal Properties of Jatropha Seeds
The thermal properties of Jatropha seeds were investigated for two accessions and in the moisture range of 4 - 16% db. Specific heat was determined using the method of mixtures, bulk thermal diffusivity was determined using the transient method (Dickerson apparatus), while the bulk thermal conductivity was calculated. The results obtained for specific heat ranged from 739.5 – 1560.1J/kg oC for native and 667.4 – 1262.21J/kg oC for improve accessions in the above moisture range. Bulk thermal diffusivity ranged from1.1x10-6 - 1.71x10-6m2/s and 1.29x10-6 m2/s - 1.83X10-6 while bulk thermal conductivity ranged from 0.276 - 0.907 W/moC and 0.283 - 0.797 W/moC for native and improved accessions respectively. ANOVA and means separation (Duncan multiply range test) at 95% confidence level was carried out for specific heat, thermal diffusivity and thermal conductivity. ANOVA showed that moisture had a significant effect on specific heat and bulk thermal conductivity but not on bulk thermal diffusivity. The mean separation shows that for native accession a significant change occured (p<0.05) for specific heat at the moisture contents of 4 and 16%. For the improved accession, the specific heat was significantly different (p<0.05) only at moisture of 8 and 16%. For bulk thermal diffusivity, moisture did not have any significant effect (p<0.05) on either the native accession or the improved accession. Bulk thermal conductivity was significantly affected (at p<0.05) by moisture content only in the native accession but not in the improved accession. The mean separation showed that significant change (p<0.05) in thermal conductivity occurred at the moisture contents of 4 and 16%. This study also shows that increase in moisture content of Jatropha seeds increase all three thermal properties studied irrespective of the accession. Regression analysis shows a high R square grater than 0.9 for all thermal properties studied.