Example 34.1 Entropy Production in a Steam Turbine Known: P1 =30 bar T =400°C Wey =540 kJ/kg steam expands through V1=160m/s a turbine at steady state. steam Find: Gev/m D>T2=100C Tb=350K- Saturated vapor V2=100m/s Sketch 30 bar 400°C Assumption: 1.CV,(1,1,1)steady state 2.Heat transfer at T 3.△PE neglected 100C 上游充通大学 April 26,2018 6 SHANGHAI JLAO TONG UNIVERSITY
April 26, 2018 6 Example 34.1 Entropy Production in a Steam Turbine Find: steam Known: steam expands through a turbine at steady state. CV / m Assumption: 1. CV, (1,1,1) steady state 2. Heat transfer at Tb 3. ∆PE neglected Sketch ?
Solution 30 bar 400°C Steady state,(1,1,1) Mass balance: 100C 0=m1-2 Entropy rate balance: ris-mi2s2 +ev To 0 三 s+is)o T 上游究通大学 April 26,2018 7 SHANGHAI JLAO TONG UNIVERSITY
April 26, 2018 7 Solution Steady state, (1,1,1) Mass balance: Entropy rate balance: