Evaluate the chemical exergy of the fuel given in column (1) of table 1, at 25 °C, 1 atm in kJ/kg. Using eq.
13.36, evaluate the chemical exergy for an environment corresponding to the table 2 below, obeying the ideal
gas model (composition in a molar basis) (see example 13.12)
Compare your results with the value of the Standard Chemical Exergy reported in table 1 above by calculating
the ratio (Chemical exergy calculated)/(Standard Chemical Exergy). What are your comments about this ratio?
TABLE 2 (components at 25 °C, 1 atm)
Fuel N2 (%) O2 (%) H2O (%) CO2 (%) Other (%)
Methane 76.0 20.44 2.65 0.08 0.83
CH4
Where coefficients a, b and c refers to $C_aH_bO_c$ of the fuel
$\bar{e}^{ch} = \left[ \bar{g}_f + \left( a + \frac{b}{4} - \frac{c}{2} \right) \bar{g}_{O_2} - a\bar{g}_{CO_2} - \frac{b}{2} \bar{g}_{H_2O(g)} \right] \left( T_o, p_o \right)$
$\qquad + RT_o \ln \left[ \frac{(y_{O_2})^{a + b/4 - c/2}}{(y_{CO_2})^a (y_{H_2O})^{b/2}} \right]$
(13.36)
