= Brayton-Carnot efficiency comparison
{c}
{title2=$\eta_C-\eta_B=r^{-1}(1-T_A/T_B)>0$}
For constant-pressure <heat> addition $A\to B$ and two <reversible ideal-gas adiabats>, set $r=(p_h/p_l)^{(\gamma-1)/\gamma}$. The <Brayton cycle> has $\eta_B=1-1/r$, maximum <temperature> $T_B$ and minimum $T_D=T_A/r$. A <Carnot cycle> using those extreme <temperatures> has the strictly greater efficiency displayed whenever $T_B>T_A$. Reversibility of the isobaric heating requires continuously matched reservoir <temperatures>, rather than <heat> transfer solely at the maximum <temperature>.
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