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Determining efficiency of fuel cells 
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#1
Dec1912, 04:28 PM

P: 7

Hi
I need to compare solid working with [itex] \frac{1}{2}O_{2}+H_{2}O+2e^{} \rightarrow 2OH^{} [/itex] and [itex]H_{2}+2OH^{} \rightarrow 2H_{2}O+2e^{}[/itex] and liquid fuel cells working with [itex] H_{2}\rightarrow 2H^{+}+2e^{} [/itex] and [itex] \frac{1}{2}O_{2}+2H^{+}+2e^{} \rightarrow H_{2}O [/itex] My idea was to compare the required electrical energy (which I know by [itex] dt U I [/itex] and the chemical energy given by [itex] Q \cdot n_{H_{2}O}=Q\cdot n_{H_{2}O}=Q\cdot\nu_{gas}\cdot n_{O_{2}}=Q\cdot\nu_{O_{2}}\cdot\frac{PV_{O_{2}}}{n_{O_{2}}RT} [/itex] where [itex] \nu _{O_{2}} [itex] is a coefficient that is equal to 1/2 in the case of solid fluel cells. My question is simple: what is [itex] \nu _{O_{2}} [itex] equal to in the case of liquid cell since there is a double equation and that we don't know which portion of OH^{} of the reductive equation is used in the oxydative equation. Any help would be helpful, thanks 


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