Question

Liquid water at 300 kPa and 25°C is heated in a chamber by mixing it with steam at 300 kPa and 200°C as in the figure below. Liquid water enters the chamber at a rate of 3.0 kg/s, and the chamber is estimated to lose heat to the surrounding air at 25°C at a rate of 35 kW. If the mixture leaves the mixing chamber at 300 kPa and 120°C, establish: a. Mass flow rate of the superheated steam, kg/s b. the overall rate of entropy change (isolated system), kW/K. [8 marks] → 25 kW 300 kPa, 25°C MIXING CHAMBER 300 kPa 300 kPa, 120°c 300 kP

Answer 1

325kw 300k२१, 3 kg sec हो 3ookpa, 12000 300kpa, 208c' By mass balance, mitma= his mi= mis-mis 3= miz- ma to By energy balance, Ein= Eout Steady flow, mi hit miz ha= aout a misha - States Pl=Bookla 2 hi= 104.89 kylka T 25C J Si = 0.3674 kylky

stator B = 300kla 2 Tz = 20000 I h2 = 2865.5 tylky S2=7.3115 kJ lkgkc state3 Ps= 3ookla u ha= 503-71 kJ kg T3= izie J S3 = 1.5276 ky llogh By energy balance 3C104.89) + mia (2865.5) = 25 + wig 503.71) 314.67-25=503.71 m 3 - 2865.5 m2 289.67 = 503.71 m3 – 2865.5 m2 - solving ① and @ @ mis = 3.517 kg /sec m2=0.517 kg/sec 6 Qout Tout overall entropy change .. By entorpy balance misit masa-miss - bout +Sgonzo Sgen = missa-mi si maiz+ Cout = 3.517(1.5276)-3(0-3674) – 6.517(7.3115) + 25 (25+273) Sgen = 0.574 kw/k]