Converging nozzle temperature difference - Steady flow energy equation

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SUMMARY

The discussion focuses on calculating the exit temperature of air in a converging nozzle using the steady flow energy equation (SFEE). The inlet conditions are 50 m/s velocity and 25°C temperature, with an exit velocity of 150 m/s. The correct exit temperature, determined through proper application of the SFEE and unit conversions, is 15.1°C. The user initially struggled with unit conversions for specific heat capacity (Cp) but successfully resolved the issue with guidance from forum members.

PREREQUISITES
  • Understanding of the steady flow energy equation (SFEE)
  • Knowledge of specific heat capacity (Cp) and its units
  • Familiarity with control volume analysis in thermodynamics
  • Basic principles of fluid dynamics, particularly in compressible flow
NEXT STEPS
  • Review the application of the steady flow energy equation in various flow scenarios
  • Study unit conversions for thermodynamic properties, especially specific heat capacities
  • Learn about compressible flow dynamics and the behavior of gases in nozzles
  • Explore additional thermodynamic principles relevant to energy transfer in fluid systems
USEFUL FOR

This discussion is beneficial for civil engineers transitioning to nuclear energy, thermodynamics students, and anyone involved in fluid dynamics or energy systems analysis.

Nuclear_eng
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I come from a civil engineering background and I'm about to start a masters in nuclear energy. I have no experience in thermodynamics and I've been doing a bit of revision before the course commences to get me up to speed. I've been working my way through 15 revision questions and I only have a couple left now. I posted a question on this forum yesterday but I'm stuck again with a different type of question on flow processes. This is meant to be one of the easiest questions in my revision booklet but so far the answer has eluded me.

Homework Statement



A converging nozzle is used to accelerate a flow of air from 50m/s at the inlet to 150m/s at the exit. The air temperature is 25°C at the inlet. Assuming heat transfer to the air is negligible, use the steady flow energy equation to calculate the temperature at the exit.

Homework Equations



Steady flow energy equation:

h1+0.5V12+gZ1=h2+0.5V22+gZ2


The Attempt at a Solution



I've revised control volume analysis and steady flow processes but I'm not getting anywhere with this. I assume it will be a very simple calculation as all the other 'easy' revision questions have taken me about a minute or two.

The correct answer is 15.1°C
 
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Is there no one who can help me? I've been looking at this similar question I found on the forums and I can't get 184°C by using the SFEE. I think I must be making a mistake with the units or something really stupid.

https://www.physicsforums.com/showthread.php?t=249494

Could somebody please just plug the numbers in and show me how he got 184°C? I would imagine it will take less than a minute and it would be a massive help to me.

Thanks
 
Use the energy equation you have above. The enthalpy is Cp*T. Ensure you get the units correct on the V^2/(2g) term.
15.1 C is indeed correct.
 
Thank you very much Lawrence. I was getting my units for Cp messed up but I've now managed to get 15.1°C.
 

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