Entropy of a Pure Substance

• Entropy is a thermodynamic property, the value of entropy depends on the state of the system. For example: given T & P, entropy, S, can be obtained from a thermodynamic table just like v, u, h.

• If the state is a mixture of liquid and vapor, the entropy can be determined as: s = sf + xsfg, where x is the quality and sf and sfg are saturated values listed in the saturation table.

• For compressible liquid, the entropy can be approximated by the entropy of the saturated liquid at the given temperature since it is not a function of pressure: s@T,P ? sf@T

Next slide

Back to first slide

View graphic version