Equation (7) signifies that the total entropy of the total system(the two reservoirs + fluid) increases for the real engine, because the entropy gain of the cold reservoir as Q C {\displaystyle Q_{\text{C}}} flows into it at the fixed temperature T C {\displaystyle T_{\text{C}}} , is greater than the entropy loss of the hot reservoir as Q H {\displaystyle Q_{\text{H}}} leaves it at its fixed temperature T H {\displaystyle T_{\text{H}}} . The inequality in Equation (7) is essentially the statement of the Clausius theorem.