The higher heating value of a hydrocarbon fuel C_nH_m with m = 8 is given to be 1340 MJ/kmol of fuel. Then its lower heating value is

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Quizplus · Accepted Answer

Solved by EES Software. Solutions can be verified by copying-and-pasting the following lines on a blank EES screen. 
HHV=1340 "MJ/kmol fuel"
h_fg=2.4423 "MJ/kg, Enthalpy of vaporization of water at 25C"
n_H=8
n_H2O=n_H/2
m_water=n_H2O*18
LHV=HHV-h_fg*m_water
"Some Wrong Solutions with Common Mistakes:"
W1_LHV=HHV - h_fg*n_H2O "Using mole numbers instead of mass"
W2_LHV= HHV - h_fg*m_water*2 "Taking mole numbers of H2O to be m instead of m/2"
W3_LHV= HHV - h_fg*m_water*2 "Taking mole numbers of H2O to be m instead of m/2, and using mole numbers"

The Higher Heating Value of a Hydrocarbon Fuel CnHm with M

The Higher Heating Value of a Hydrocarbon Fuel C_nH_m with M