Heat input to a cycle
= Heat input to a cycle
{title2=$Q_{\rm in}=\int_{\delta Q>0}\delta Q$}
The <heat input to a cycle> sums positive transfers of <heat> into its working substance. It is not the net <heat> over the entire cycle, which equals net <work>. A single geometric branch can contain both heat absorption and rejection, so grouping the branch into one net transfer can overestimate a <heat engine>'s <thermal efficiency>.