蒸気圧縮冷凍サイクル
h5 = h6 と置き換えて、
1 + m = h 2 − h 7 h 3 − h 5 {\displaystyle 1+m={\frac {h_{2}-h_{7}}{h_{3}-h_{5}}}}
したがって成績係数は
( C O P ) R = q c w = h 1 − h 7 h 2 − h 1 + h 2 − h 7 h 3 − h 5 ( h 4 − h 3 ) = ( h 3 − h 5 ) ( h 1 − h 7 ) ( h 3 − h 5 ) ( h 2 − h 1 ) + ( h 2 − h 7 ) ( h 4 − h 3 ) {\displaystyle {\begin{aligned}\mathrm {(COP)_{R}} &={\frac {q_{c}}{w}}={\frac {h_{1}-h_{7}}{h_{2}-h_{1}+{\frac {h_{2}-h_{7}}{h_{3}-h_{5}}}(h_{4}-h_{3})}}\\&={\frac {(h_{3}-h_{5})(h_{1}-h_{7})}{(h_{3}-h_{5})(h_{2}-h_{1})+(h_{2}-h_{7})(h_{4}-h_{3})}}\end{aligned}}}
となる。