2013-3-6 Introducing Vapor Power Plants Subsystem D removes energy by heat transfer arising from steam condensing in subsystem B. Introducing Vapor Power Plants Each unit of mass of water periodically undergoes a thermodynamic cycle as it circulates through the components of subsystem B.This cycle is the Rankine cycle. 8 2013-3-6 8 Introducing Vapor Power Plants ►Subsystem D removes energy by heat transfer arising from steam condensing in subsystem B. Introducing Vapor Power Plants ►Each unit of mass of water periodically undergoes a thermodynamic cycle as it circulates through the components of subsystem B. This cycle is the Rankine cycle