ABSTRACT
Objectives ◾ Illustrate the stability and present analogy between mechanical and thermodynamic stability ◾ Present mathematical criteria for stability in terms of thermodynamic variables ◾ Discuss applications to boiling and condensation ◾ Irreversible transformations between various stable states and entropy generation ◾ Present spinodal curves and relate to degree of subcooling and superheating of fluids
10.1 Introduction It has been known that if water is heated in a microwave oven, sometimes the water does not appear to boil but when removed it may explode due to the concentration of energy at a few spots within the water (i.e., without diffusion of heat or when there is no local disturbance). Œe manufacturer warns that the water can get superheated in liquid state beyond 100°C without bubbling but can bubble when a spoon or tea bag is inserted (i.e., when a disturbance is created). Œis chapter will explain such a phenomenon using the entropy maximum and energy minimum principles, these will be used to derive the stability criteria for a fluid that exists at a specified state. Œis will allow us to stipulate the phase change conditions (e.g., evaporation and condensation) for single and multicomponent fluids. Applications will also be presented.
