Heater.. The steady flow equation as applied to a fluid heater..

Potential energy (z) assumed to be constant..
Kinetic energy changes (1 to 2) assumed to be very small

Heater

w = 0 therefore 
q = h₂-h₁

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Turbine ..(Assumed Adiabetic Expansion)..The steady flow equation as applied to a turbine..

Potential energy (z) assumed to be constant..
Kinetic energy changes (1 to 2) assumed to be very small

 Turbine

q = 0 therefore 
w = h₂-h₁

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Throttling ..(Assumed Adiabetic )...The steady flow equation as applied to a orifice..

Potential energy (z) assumed to be constant..
The higher velocity at orifice section is dissipated in tube downstream of the orifice and therefore the kinetic energies at 1 and 2 are similar

Orifice

q = w = 0 therefore 
therefore h₁ = h₂

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Nozzle..(Assumed Adiabetic )...The steady flow equation as applied to smooth nozzle..

Potential energy (z) assumed to be constant..
Kinetic energy changes are assumed to be significant

Nozzle

q = w = 0 therefore 
(v₂² - v₁² ) /2 = (h₁ - h₂ )