value from steam table for T1 = 200 CH = 2826.8S = 6.6922 [3] Redo Example 6.9 (textbook pages 245-246) part (a) only except with t₁=200 °C. Determine down-stream state and ΔΗ. Example 6.9Superheated steam originally at P₁ and T₁ expands through a nozzle to an exhaust pres-sure P₂. Assuming the process is reversible and adiabatic, determine the downstreamstate of the steam and AH for P₁ = 1000 kPa, t₁ 250°C, and P₂ = 200 kPa.=Solution 6.9Because the process is both reversible and adiabatic, there is no change in theentropy of the steam. For the initial temperature of 250°C at 1000 kPa, no entriesappear in the tables for superheated steam. Interpolation between values for 240°Cand 260°C yields, at 1000 kPa,H₁ = 2942.9 kJ-kg-111-For the final state at 200 kPa,Numerically,S₁ = 6.9252 kJ.kg-¹.K-1Because the entropy of saturated vapor at 200 Pa is greater than S2, the final statemust lie in the two-phase liquid/vapor region. Thus t2 is the saturation tempera-ture at 200 kPa, given in the superheat tables as t₂ = 120.23°C. Equation (6.96a)t2applied to the entropy becomes:S₂ = (1-x₂)S₂ + x₂ S ₂S₂ S₁ = 6.9252 kJ.kg-¹.K-1=6.9252 = 1.5301(1-x2)+7.1268x2where the values 1.5301 and 7.1268 are entropies of saturated liquid and saturatedvapor at 200 kPa. Solving,Finally,x₂ = 0.9640The mixture is 96.40% vapor and 3.60% liquid. Its enthalpy is obtained by furtherapplication of Eq. (6.96a):H₂ = (0.0360)(504.7) + (0.9640)(2706.3) = 2627.0 kJ·kg−¹AH = H₂ - H₁ = 2627.0 2942.9 = -315.9 kJ.kg-1For a nozzle, under the stated assumptions the steady-flow energy balance,Eq. (2.31), becomes1AH+=Au² = 024u²Thus the decrease in enthalpy is exactly compensated by an increase in kineticenergy of the fluid. In other words, the velocity of a fluid increases as it flowsthrough a nozzle, which is its usual purpose. Nozzles are treated further in Sec. 7.1.

Question

Accepted Answer

given = P1 = 1000 KPa T1 = 200^c and P2 = 200 KPa
since the process is both reversible and adiabatic…

[3] Redo Example 6.9 (textbook pages 245-246) part (a) only except with t₁-200 °C. Determine down- stream state and ΔΗ.