EML4550HW7ans

EML4550HW7ans - 1 Examine how the ideal efficiency of a...

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1. Examine how the ideal efficiency of a simple hydrogen-oxygen fuel cell changes as its operating temperature is raised from 298K to 750K: Given: T 298 299 , 750 .. := kJ 1000J := Constants: a h2o 30.62644 := b h2o .009621 := c h2o 1.18 10 6 := a h2 28.91404 := b h2 .00084 := c h2 2.01 10 6 := a o2 25.84512 := b o2 .012987 := c o2 3.9 10 6 := Using HHV value at 298K for Δ H and Δ S: Δ H 298 286.02 kJ mol := Δ S 298 .1633 kJ mol := Difference in the empirical coefficients: Δ aa h2o a h2 1 2 a o2 kJ mol := Δ bb h2o b h2 1 2 b o2 kJ mol := Δ cc h2o c h2 1 2 c o2 kJ mol := Change in enthalpy and entropy as a function of temperature: Δ HT () Δ H 298 Δ a 1000 T 298 + Δ b 1000 T 298 2 2 + Δ c 1000 T 298 3 3 + := Δ ST Δ S 298 Δ a 1000 ln T 298 + Δ b 1000 T 298 + Δ c 1000 T 298 2 2 + := Gibbs free energy equation: Δ GT Δ () T Δ := Ideal efficiency: η
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EML4550HW7ans - 1 Examine how the ideal efficiency of a...

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