BeginnerTopic 19 of 105Thermodynamics & Fluids
Steady-flow devices
Turbines, compressors, nozzles, diffusers and heat exchangers analysed with the first law.
In depth
Nozzles accelerate fluid (pressure drops), diffusers decelerate, turbines produce work, compressors and pumps consume it, heat exchangers transfer heat between streams, mixing chambers combine flows. Each has simplifying assumptions (adiabatic, Δpe=0 etc.).
Key points
- Nozzle exit velocity √(2Δh)
- Turbine work ṁΔh
- Pump work v ΔP
ExampleA steam turbine with Δh=800 kJ/kg and 10 kg/s yields 8 MW.
What is Steady-flow devices?
Turbines, compressors, nozzles, diffusers and heat exchangers analysed with the first law.
Why is it important to understand steady-flow devices?
Steady flow devices are the core components of power plants and refrigeration systems, so their energy analysis is an essential design step.
What is a nozzle in thermodynamic analysis?
A device that increases fluid velocity by reducing pressure, with little work and often negligible heat transfer.
What does a heat exchanger do in the energy balance?
It transfers heat between two streams without work, so the heat lost by one stream equals the heat gained by the other.
How is Steady-flow devices used in practice?
Typical applications include estimating the power output of a steam turbine from inlet and outlet enthalpies, calculating the work of a compressor in a refrigeration plant and sizing a nozzle to accelerate a steam jet for an ejector.
What should I learn before Steady-flow devices?
Study "Energy balance for control volumes" first (topic 18 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
What are the key points of Steady-flow devices?
Nozzle exit velocity √(2Δh). Turbine work ṁΔh. Pump work v ΔP.
Can you give an example of Steady-flow devices?
A steam turbine with Δh=800 kJ/kg and 10 kg/s yields 8 MW.
What comes after Steady-flow devices?
The next topic is "Throttling", which builds directly on this one.
How difficult is Steady-flow devices?
It is classed as Beginner in Thermodynamics & Fluids (topic 19 of 105). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.