Effects of combined pretreatment with rod-milled and torrefaction on physicochemical and fuel characteristics of wheat straw.

•Rod-milling improved the devolatilization index of wheat straw under identical torrefaction conditions except 275 °C.•Rod-milling combined with torrefaction changed the thermal degradation mechanism of wheat straw.•Combined pretreatment is conducive to the energy utilization of wheat straw.