Thermodynamics: Brayton Refrigeration Cycle with Regenerator

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SUMMARY

The discussion focuses on the Brayton refrigeration cycle with a regenerator, specifically addressing the calculations for enthalpy values and regenerator effectiveness. Given parameters include an inlet temperature (Ti) of 0°C, a mass flow rate of 0.4 kg/s, turbine efficiency of 0.85, and compressor efficiency of 0.8. The user has calculated enthalpy values h1, h2, h3, and h5, and seeks to determine the enthalpy values h4 and h6, as well as the regenerator effectiveness. The effectiveness formula is identified as Et=(h1-h3)/(h4-h3), emphasizing the relationship between h4 and h1.

PREREQUISITES
  • Understanding of the Brayton refrigeration cycle
  • Knowledge of thermodynamic properties and enthalpy calculations
  • Familiarity with turbine and compressor efficiency concepts
  • Basic principles of heat exchangers and regenerator effectiveness
NEXT STEPS
  • Calculate h4 and h6 using the given turbine and compressor efficiencies
  • Research methods for determining real enthalpy values in non-ideal systems
  • Study the impact of regenerator effectiveness on overall system performance
  • Explore advanced thermodynamic cycles that incorporate regenerative processes
USEFUL FOR

Mechanical engineers, thermodynamics students, and professionals involved in refrigeration cycle design and optimization will benefit from this discussion.

Robin Ghoul
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I have a brayton refrigeration cycle with a regeneator same as the picture below only with irreversible regenrator, compressor and turbine (And different values).
p-10e-1a_12666_image010.gif

The given in my problem are:
Ti=0 C, T3= 35 C, T5= -80 C, mass flow rate m= 0.4 kg/s
Turbine efficiency Et=0.85, Compressor efficiency =0.8 and pressure ratio =5
I found h1=273.3 KJ/Kg, h2=552.27 KJ/Kg, h3= 308.5 KJ/Kg, h5=193 KJ/kg
I need to find the regenerator effectiveness
My question are:
1-How to find h4 and h6
2-What is the regenrator efficiency in this case I know if the regenerator was ideal the h4=h1, but I am unable to find the real h4, maybe it has to do with the turbine efficiency but I only have the real h5 I need h5s to find h4...
As fir the regenerator effectiveness I thought it would be Et=(h1-h3)/(h4-h3).. as h4 approaches h1, the effectiveness approaches 1
 
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Also, specific heats are at room temperature
 

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