Thermodynamic Properties 2

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  1. What is the equation for the speed of sound?
    chart?chf=bg,s,00000000&cht=tx&chl=a%3D%5Csqrt%7Bkg_c%20RT&chs=196x60
  2. How can a new speed of sound be calculated when the temperature changes?
    chart?chf=bg,s,00000000&cht=tx&chl=%5Cfrac%7Ba_1%7D%7Ba_2%7D%3D%5Csqrt%7B%5Cfrac%7BT_1%7D%7BT_2%7D%7D&chs=156x94
  3. Thermal efficiency is the ratio of useful work output to energy input. What equation results from combining this definition with the First Law of thermodynamics?
    chart?chf=bg,s,00000000&cht=tx&chl=%5Ceta_%7Bth%7D%3D%5Cfrac%7BW_%7Bout%7D-W_%7Bin%7D%7D%7BQ_%7Bin%7D%7D&chs=246x82chart?chf=bg,s,00000000&cht=tx&chl=%3D%5Cfrac%7BW_%7Bnet%7D%7D%7BQ_%7Bin%7D%7D&chs=106x82

    First Law: chart?chf=bg,s,00000000&cht=tx&chl=W_%7Bnet%7D%3DQ_%7Bin%7D-Q_%7Bout%7D&chs=270x42

    So:  chart?chf=bg,s,00000000&cht=tx&chl=%5Ceta_%7Bth%7D%3D%5Cfrac%7BQ_%7Bin%7D-Q_%7Bout%7D%7D%7BQ_%7Bin%7D%7D&chs=230x90
  4. What equation describes the First Law of thermodynamics for closed systems, and what does the equation mean?
    Qin = ΔU+W

    Any heat entering a closed system can either increase the energy of the system (U) or be used to perform work on the surroundings.
  5. What is the equation for thermal efficiency?
    chart?chf=bg,s,00000000&cht=tx&chl=%5Ceta_%7Bth%7D%3D%20%5Cfrac%7BW_%7Bnet%7D%7D%7BQ_%7Bin%7D&chs=160x82
  6. What is the Second Law of thermodynamics?
    Entropy must always increase in a real process or cycle.
  7. Identify lines of constant pressure.
    Image Upload 1
    Image Upload 2
  8. Identify lines of constant superheat.
    Image Upload 3
    Image Upload 4
  9. Identify lines of constant moisture.
    Image Upload 5
    Image Upload 6
  10. What equation calculates the quality of a vapor-liquid mixture?
    chart?chf=bg,s,00000000&cht=tx&chl=x%3D%5Cfrac%7Bm_%7Bvapor%7D%7D%7Bm_%7Bvapor%7D%2Bm_%7Bliquid%7D%7D&chs=274x70
  11. What equation gives the enthalpy of a liquid-vapor mixture?
    chart?chf=bg,s,00000000&cht=tx&chl=h%3Dh_f%2Bxh_%7Bfg%7D&chs=214x36

    Similar equations apply for internal energy (u) and entropy (s).
  12. What can be said of the kinetic and potential energies of a closed system?
    The kinetic and potential energies of a closed system are negligible.
  13. In the steady flow energy equation, break apart the enthalpy component and make note of the units.

    chart?chf=bg,s,00000000&cht=tx&chl=q%3D%5CDelta%20h%2B%5CDelta%20e_p&chs=206x38chart?chf=bg,s,00000000&cht=tx&chl=%2B%5CDelta%20e_k%2Bw_%7Bshaft%7D&chs=228x46
    chart?chf=bg,s,00000000&cht=tx&chl=%5CDelta%20h%3D%5CDelta%20u%20%2B%20w_%7Bflow%7D&chs=262x46

    and 

    chart?chf=bg,s,00000000&cht=tx&chl=w_%7Bflow%7D%3D%5Cfrac%7Bp_2v_2-p_1v_1%7D%7BJ&chs=274x70

    units are BTU/lbm, and J=778.17 ft-lbf/BTU
  14. In the steady flow energy equation, break apart the potential energy component and make note of the units.
    chart?chf=bg,s,00000000&cht=tx&chl=q%3D%5CDelta%20h%2B%5CDelta%20e_p&chs=206x38chart?chf=bg,s,00000000&cht=tx&chl=%2B%5CDelta%20e_k%2Bw_%7Bshaft%7D&chs=228x46
    chart?chf=bg,s,00000000&cht=tx&chl=%5CDelta%20e_p%3D%5Cfrac%7B(z_2-z_1)g%7D%7Bg_cJ%7D&chs=230x88

    units are BTU/lbm, and J=778.17 ft-lbf/BTU
  15. In the steady flow energy equation, break apart the kinetic energy component and make note of the units.
    chart?chf=bg,s,00000000&cht=tx&chl=q%3D%5CDelta%20h%2B%5CDelta%20e_p&chs=206x38chart?chf=bg,s,00000000&cht=tx&chl=%2B%5CDelta%20e_k%2Bw_%7Bshaft%7D&chs=228x46
    chart?chf=bg,s,00000000&cht=tx&chl=%5CDelta%20e_k%3D%5Cfrac%7B(v_2%5E%5E2-v_1%5E%5E2)%7D%7B2g_cJ%7D&chs=236x88

    units are BTU/lbm, and J=778.17 ft-lbf/BTU
  16. In the steady flow energy equation, break apart the shaft work component and make note of the units.
    chart?chf=bg,s,00000000&cht=tx&chl=q%3D%5CDelta%20h%2B%5CDelta%20e_p&chs=206x38chart?chf=bg,s,00000000&cht=tx&chl=%2B%5CDelta%20e_k%2Bw_%7Bshaft%7D&chs=228x46
    chart?chf=bg,s,00000000&cht=tx&chl=%5Cfrac%7Bw_%7Bshaft%7D(ft-lbf%2Flbm)%7D%7BJ(ft-lbf%2FBTU)%7D&chs=282x90

    units are BTU/lbm, and J=778.17 ft-lbf/BTU
  17. Identify the lines of constant temperature ratio on this graph of compressibility factors, and define the ratios for temperature and pressure.
    Image Upload 7
    Image Upload 8

    P/Pc and T/Tc are calculated using critical temperature and pressure listed in a chapter table.
  18. What is the relationship between power, mass flow and change in internal energy?
    chart?chf=bg,s,00000000&cht=tx&chl=P%3D%5Cdot%20m%20%5CDelta%20u&chs=150x30
  19. What is the relationship between power, force and speed?
    P=Fv
  20. How do you calculate a thermodynamic property (such as cp) of a non-reacting mixture?
    • Calculate the gravimatric fraction of each constituent chart?chf=bg,s,00000000&cht=tx&chl=G_i%3D%5Cfrac%7Bm_i%7D%7B%5Csum_i%7Bm_i%7D%7D&chs=160x78
    • and use this relationship chart?chf=bg,s,00000000&cht=tx&chl=c_p%3D%5Csum_i%7BG_i%20c_%7Bp%2Ci%7D&chs=220x80
  21. What is the relationship between power, torque and rotational speed?
    P=Tω
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307733
Card Set
Thermodynamic Properties 2
Description
Mechanical Professional Engineering Exam Review
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