Entropy

Abstract

The first step in our consideration of the property we call entropy is to establish what is generally known as the inequality of Clausius, thus where the equality sign holds for reversible cycles and the inequality for irreversible cycles. Here, the left-hand side is the cyclic integral of all heat quantities δQ divided by the temperature T at each point of heat addition. We can demonstrate the validity of equation 4.1 by considering both an externally reversible engine R (operating on the Carnot cycle, see figure 3.7) and an irreversible engine X operating between two temperature reservoirs, as shown in figure 4.1. Both engines are assumed to extract the same quantity of heat Q_in from T_H.