Thermodynamics: isentropic efficiency and ideal gas model

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SUMMARY

The discussion centers on the calculation of work developed by a turbine and the exit temperature using the ideal gas model for air at 1175 K and 8 bar, expanding adiabatically to 1 bar with an isentropic efficiency of 92%. The professor's provided answers are W = 486 kJ/kg and T2 = 691 K. Discrepancies arise from different enthalpy tables used for temperature conversion, leading to variations in calculated results. The credibility of external solutions is questioned due to potential unit errors in temperature.

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jofree87
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Air at 1175 K, 8 bar enters a turbine operating at steady state and expands adiabatically to 1 bar. The isentropic turbine efficiency is 92%. Employing the ideal gas model with k=1.4 for the air, determine (a) the work developed by the turbine, in kJ per kg of air flowing, and (b) the temperature at the exit, in K. Ignore kinetic and potential energy effects.

The answers my professor provided are W = 486 kJ/kg, and T2 = 691 K

I found a solution (attached below) on another website that comes up with different answers. The work on the solution looks to be correct, but why do the answers differ? Which answers are correct?
 

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maybe the tables used for finding enthalpy from temperature is different. are you sure about the credibility of the image? the guy has the units of temperature wrong ( mayb just a silly mistake).
 

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