What you will learn
Define system boundaries and states; apply the first law qualitatively and quantitatively; distinguish heat from temperature; compare conduction, convection and radiation; interpret cycle efficiency.
Course syllabus
- 1. States and energy balances
System boundaries, properties and the first law
- 2. Heat transfer
Conduction, convection, radiation and thermal resistance
- 3. Cycles and efficiency
Why no energy-conversion system reaches 100 percent
Free lesson · 36m
System boundaries, properties and the first law
Thermodynamics starts by defining the system and its boundary. A closed system exchanges energy but not mass; a control volume can exchange both. State properties such as pressure, temperature and specific volume describe equilibrium conditions, while heat and work describe energy crossing the boundary.
The first law is an accounting rule: change in stored energy equals energy entering minus energy leaving. For steady-flow equipment, mass flow carries enthalpy and kinetic or potential energy. The useful form depends on whether you study a tank, heat exchanger, turbine, compressor or complete plant.
Write the boundary, reference direction, assumptions and units before simplifying. An omitted stream or hidden electrical input can make a perfectly solved equation describe the wrong system.
Define the system first; properties belong to states while heat and work cross boundaries; energy is conserved; document streams, directions and assumptions.