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ENGR5003 / Week 5
Lecture 13 worked example 1 - ideal Rankine cycleTutorialCurrent spec2:218 min

ENGR5003 Lecture 13 worked example 1 (slides 9-10)

An ideal Rankine cycle operates with water as the working fluid. Steam enters the turbine as superheated vapour at 3 MPa and 350 ∘C350\ ^\circ\mathrm{C}. It expands isentropically to a condenser pressure of 10 kPa, where it condenses into a saturated liquid. The liquid is then pumped back to the boiler. Determine:

Formulas you may need
  • SFEE, adiabatic, negligible KE and PE: w=hin−houtw = h_{in} - h_{out}; q=hout−hinq = h_{out} - h_{in} (on the formula sheet)
  • Wet steam: s=(1−x)sf+xsgs = (1 - x)s_f + xs_g, h=(1−x)hf+xhgh = (1 - x)h_f + xh_g (on the formula sheet)
  • Pump work for an incompressible liquid: wp=vf(p2−p1)w_p = v_f(p_2 - p_1) (learn this)
  • Back work ratio rbw=win/woutr_{bw} = w_{in}/w_{out}; ηth=wnet/qin\eta_{th} = w_{net}/q_{in} (on the formula sheet)
  1. (a)
    Sketch the T-s diagram and label all four states.
  2. (b)
    The turbine work, pump work and net work output.
  3. (c)
    The heat input and thermal efficiency (also give the back work ratio).