Continue Rankine Cycle Performance Trends Continue effect of boiler pressure on performance: .Assume:TC=66C [pc=Psat(Tc)=0.255 bar] x4=0.95 [specifies T3] TB(C) Pg (bar) T3(C) 7 232 29 400 0.246 288 72 506 0.290 343 153 604 0.324 Notes: T3 increases faster than TBoiling t to maintain X4 maximum pressure dictated by temperature of heat source and materials optimal pressure:trade-off between 1st costs and operating costs 上游充通大学 Wednesday,May 03,2017 6 HANGHAI JLAO TONG UNIVERSITY
Wednesday, May 03, 2017 6 Continue Rankine Cycle Performance Trends Continue effect of boiler pressure on performance: • Assume: TC = 66oC [pC = psat(TC ) = 0.255 bar] x4 = 0.95 [specifies T3 ] TB ( oC) pB (bar) T3 ( oC) h 232 29 400 0.246 288 72 506 0.290 343 153 604 0.324 Notes: • T3 increases faster than TBoiling to maintain x4 • maximum pressure dictated by temperature of heat source and materials • optimal pressure: trade-off between 1st costs and operating costs
Continue Rankine Cycle Performance Trends Effect of condensing pressure on performance: Lower condenser pressure increase work output at the same heat input >Increase in efficiency -Lower limit depends on environmental temperature P4<P4 Lowering pressure Increase in Wnet decreases quality →Must increase T3to keep quality constant 上游充通大 Wednesday,May 03,2017 7 SHANGHAI JIAO TONG UNIVERSITY
Wednesday, May 03, 2017 7 Continue Rankine Cycle Performance Trends Effect of condensing pressure on performance: - Lower condenser pressure increase work output at the same heat input Increase in efficiency -Lower limit depends on environmental temperature - Lowering pressure decreases quality Must increase T3 to keep quality constant