Example 15.3 Gas in a closed cylinder,reversible polytropic P1=8MPa expansion process from p=8MPa,t =1 300C to t=1300C p2=0.4MPa,t2=400℃. Given R=0.287 kJ/(kg.K)and constant specific heat p2=0.4MPa Cv=0.716 kJ/(kg-K). t2=400C ● Determine:gas receiving or rejecting heat? Solution: Ideal gas EoS applied to the initial and final states RT 287J/kgK)×(1300+273)K V =0.05643m3/kg P 8×106Pa RT ,287J/kg·K)×(400+273)K V2= =0.48288m3/kg P2 0.4×106Pa 上游充通大 March 23,2018 17 SHANGHAI JIAO TONG UNIVERSITYMarch 23, 2018 17 Gas in a closed cylinder, reversible polytropic expansion process from p1 = 8MPa, t1 =1 300℃ to p2= 0.4 MPa, t2= 400℃. Given R=0.287 kJ/(kg·K) and constant specific heat cV= 0.716 kJ/(kg·K) . Determine: gas receiving or rejecting heat? Solution:   1 3 1 6 1 287 J/(kg K) 1 300 273 K 0.056 43 m / kg 8 10 Pa RT v p        Ideal gas EoS applied to the initial and final states   2 3 2 6 2 287 J/(kg K) 400 273 K 0.482 88 m / kg 0.4 10 Pa RT v p        Example 15.3 v p p1 = 8MPa t1 =1300°C p2 = 0.4MPa t2 =400°C