Old spec L5 worked example 3 - isentropic expansion of dry steam, closed vs open (ENGR5003) - Revisica

Old spec L5 worked example 3 - isentropic expansion of dry steam, closed vs openTutorialOld spec ENGR217Third8 min

ENGR217 Lecture 5 steam tables worked example 3 (slides 17-19)

Dry saturated steam at 5 bar is expanded isentropically (constant entropy) to a final pressure of 1 bar. Determine the dryness fraction at 1 bar. What is the specific work done if:

Formulas you may need

Wet steam: $s = (1 - x)s_f + xs_g$ (and the same for $u$ , $h$ ) (on the formula sheet)
Closed adiabatic process: $w = -\Delta u = u_1 - u_2$ (on the formula sheet)
SFEE, adiabatic, negligible KE and PE: $w = h_1 - h_2$ (on the formula sheet)

(a)
the expansion is in a cylinder (i.e. a closed system)?
x2 =
w =kJ/kg
(b)
the expansion is through a turbine (i.e. an open system)?
w =kJ/kg

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