Question: how to calculate hhv of coal?
Answer: FORMULAS FOR CALCULATING THE HEATING VALUE OF COAL AND COAL CHAR: DEVELOPMENT, TESTS AND USES. ... 
of the United States.
Four formulas were selected for test. They are as follows: ... 
Q = 145.44 C + 620.28 H + 40.5 S - 77.54 (0)
Boie (11) Q = ... 
9 = [ ~~
+ 424.621 [C/3 + H -(0)/8 + s/8]
Mott and Spooner (1,13)