I need some clarification Thermo Cycle

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SUMMARY

The discussion centers on a thermodynamic problem involving Refrigerant 22 in a rigid closed tank. The refrigerant experiences energy transfer due to a paddle wheel operating at a constant rate of 0.1 kW, while heat is lost to the surroundings at a rate defined by a constant K. After 20 minutes, the refrigerant's pressure and internal energy change from 0.9 MPa and 232.92 kJ/kg to 1.2 MPa and 276.67 kJ/kg, respectively. The key equations used include the first law of thermodynamics, U2 - U1 = Q - W, and the work done, W = ∫p dV.

PREREQUISITES
  • Understanding of thermodynamic principles, specifically the first law of thermodynamics.
  • Familiarity with properties of refrigerants, particularly Refrigerant 22.
  • Knowledge of energy transfer concepts, including work and heat transfer.
  • Basic calculus for evaluating integrals in thermodynamic equations.
NEXT STEPS
  • Calculate the work done on the refrigerant using the integral W = ∫p dV.
  • Determine the heat transfer Q using the equation U2 - U1 = Q - W.
  • Research the method to find the constant K in the heat transfer relation.
  • Explore the properties and equations related to Refrigerant 22 for better understanding.
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Students studying thermodynamics, engineers working with refrigeration systems, and anyone looking to deepen their understanding of energy transfer in closed systems.

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I need some clarification! Thermo Cycle

Homework Statement



One kg of Refrigerant 22, initially at p1=.9MPa, u1=232.92 kJ/kG, is contained within a rigid closed tank. The tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate 0.1kW. Heat transfer from the refrigerant to its surroundings occurs at a rate Kt, in kW, where K is a constant, in kW/minute, and t is time in minutes. After 20 minutes of stirring, the refrigerant is at p2=1.2 MPa, u2=276.67 kJ/kG. No overall changes in KE or PE occur. (a) For the refrigerant, determine the Work and Heat transfer, each in kJ. (b) Determine the value of the constant K appearing in the given heat-transfer relation in kW/min.

Homework Equations



U2-U1=Q-W
W=int p*dV

The Attempt at a Solution



I guess what I really need is some clarification on the term "energy transferred in." Is this a rate of WORK?
 
Last edited:
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Can anyone give me a hint before I go to bed? Then I can mull it over and attack this problem on the subway tomorrow! :smile:
 

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