Enhancement in thermal and energy saving performance of a rotary dryer with a heat distribution pipe for convective drying of Thai jasmine rice grains

• A roto-forced air dryer with a heat distribution pipe and internal flights is assessed. • Thermal efficiency and energy use of the dryer are compared with a conventional dryer. • The optimal convective drying temperature for Thai jasmine rice grains is 100 °C. • The heat distribution pipe improves thermal efficiency (75%) and saves energy (12%). This study aimed to investigate the influence of a heat distribution pipe on the total energy consumption and thermal efficiency of a modified rotary dryer during the convective drying of Thai jasmine rice grains. The rotary dryer was tested for its performance under two scenarios: one without a heat distribution pipe and the other with a heat distribution pipe. Thai jasmine rice grains were fed at a rate of 10 kg/h. Hot air was supplied at a constant flow rate of 0.25 kg/min, with drying temperatures ranging from 80 to 100 °C, and a drum rotation speed of 15 rpm. The findings indicated that the optimal drying temperature for this process was 100 °C. The modified rotary dryer was highly effective in reducing the moisture content in Thai jasmine rice grains to 12.65%wb within 80 min, achieving a drying rate of 1.33 kg water/h and a total specific energy consumption ( SEC ) of 59.50 MJ/kg water. Compared to the configuration without the pipe, it exhibited an average increase in the drying rate of 17.9% and a remarkable reduction in the total SEC of 12.3%, achieving an outstanding thermal efficiency of 75%.