Energy balance

• The net change (increase or decrease) in the total energy of a system during a process is equal to the difference between the total energy entering and total energy leaving the system.

Energy change of a system

The energy change of a system during a process is equal to the net work and heat transfer between the system and its surroundings

Energy transfer mechanisms

• Energy can be transferred to or from a system by three mechanisms

– Heat

– Work

– Mass flow

Energy transfer mechanisms