Ultrasonic vibration-assisted pelleting of wheat straw: A predictive model for energy consumption using response surface methodology

• RSM can be successfully applied for modeling and optimizing the UV-A pelleting process.
• Energy consumption increased when ultrasonic power, sieve size, and pellet weight increased.
• Effects of pelleting pressure had no significant effects on the energy consumption in UV-A pelleting.

Cellulosic biomass can be used as a feedstock for biofuel manufacturing. Pelleting of cellulosic biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1 g, and the minimum energy consumption was 2.54 Wh.