Multi-objective optimization of graphene far-infrared paddy drying process based on response surface methodology

Abstract

Graphene exhibits exceptional electrothermal conversion efficiency, making it a promising candidate as a novel heat source for far-infrared drying. This study examined the impacts of infrared radiation temperature (45–55 °C), air flow (300–460 m3/h), and grain flow rate (6–8 kg/min) on the stress cracking index (SCI), specific energy consumption (SEC), and thermal efficiency. The Box–Behnken response surface methodology and expectation function method were employed to model and optimize the quality of far-infrared drying of paddy graphene. The findings indicate that both the drying rate and SCI of paddy increased with an increase in the infrared temperature and grain-flow rate; higher values of these parameters resulted in improved thermodynamic properties. Conversely, the SEC decreased with an increase in the infrared temperature and grain flow, whereas the thermal efficiency exhibited an inverse relationship. The influence of airflow on dried samples was negligible. Under specified constraints, the optimized drying parameters to yield a maximum expected factor were an infrared radiation air temperature of 51 °C, air flow of 377.690 m3/h, and grain flow rate of 8 kg/min. With this optimized combination of drying-process parameters, the minimum SCI reached approximately 35.4, and the minimum SEC was approximately 3734.9 kJ/kg, resulting in a maximum thermal efficiency of approximately 62.7 %. These results provide a foundation for the future development of graphene-based far-infrared grain-drying equipment.