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I've been thinking about the initial question:
The work of a turbine is the difference between inlet and outlet enthalpy, ##w_t = h_{out} - h_{in}##.
If you put a nozzle before the turbine inlet, it won't change anything for the for the turbine, because for a nozzle ##h_{out} = h_{in}##. So the same enthalpy will be available at the turbine inlet.
Enthalpy can be calculated based on total temperature, i.e. ##h = C_p T_0 = C_p \left(T + \frac{v^2}{2C_p}\right)##. Thus, for a nozzle, whatever increase in velocity you get, it will be at the expense of a temperature decrease. Enthalpy wise, you gain nothing, you loose nothing and the turbine sees the same thing.
The only reason to put a nozzle at the inlet of a turbine would be to adjust the flow conditions such that the turbine is doing its job as efficiently as possible.
pranj5 said:In case of Nitrogen at 4 barA pressure and 27°C, if a turbine is used to release the Nitrogen at 1 barA with a flowrate of 1 kg/sec; then the output is around 95 kW. Now, if the pressurised Nitrogen is released through a convergent or c/d nozzle shaped structure before the turbine, it's velocity will be higher than the previous case. Does that means effective rise in the pressure? If yes, then how much?
The work of a turbine is the difference between inlet and outlet enthalpy, ##w_t = h_{out} - h_{in}##.
If you put a nozzle before the turbine inlet, it won't change anything for the for the turbine, because for a nozzle ##h_{out} = h_{in}##. So the same enthalpy will be available at the turbine inlet.
Enthalpy can be calculated based on total temperature, i.e. ##h = C_p T_0 = C_p \left(T + \frac{v^2}{2C_p}\right)##. Thus, for a nozzle, whatever increase in velocity you get, it will be at the expense of a temperature decrease. Enthalpy wise, you gain nothing, you loose nothing and the turbine sees the same thing.
The only reason to put a nozzle at the inlet of a turbine would be to adjust the flow conditions such that the turbine is doing its job as efficiently as possible.