In Eq. (3), HRS, WRS, HRB, and WRB represent the heating value of
the powder of the rice straw with a size of 40–60 mesh (16.1 MJ/kg),
the percentage of the rice straw in the briquette, the heating value of the powder of the rice bran with a size of 40–60 mesh (20.5 MJ/kg),
the percentage of the rice bran in the briquette, respectively.