Please show work for these as the answers are given. Thanks A piston-cylinder de
ID: 787184 • Letter: P
Question
Please show work for these as the answers are given. Thanks
A piston-cylinder device with a set of stops initially contains 0.3 kg of steam at 1.0 MPa and 400degree C (State 1). The location of the stops corresponds to 60 percent of the initial volume. Now the steam is cooled. Determine the compression (moving boundary) work (kJ) if the final state is 1.0 MPa at 250degree C (State 2). Has the piston reached the set of stops at State 2? [No] Determine the heat interaction in this process (kJ). [-74.2 kJ]Explanation / Answer
assuming ideal gas behaviour ,
PV=NRT;
N=300/18= 17.33 moles
V = 17.33*8.314*673*10^-6;
v 1=0.096m^3;
after cimpression =V2 = NRT/P = 17.33*8.314*523*10^-6 = 0.075m^3;
v2/v1 = 0..78>0.6 there fore it has reached
compression work = Pdv= (10^6)0.096*0.4 = 0.0384*10^6= 38.4kJ;
heat interaction = dw +dU = 38.4 - 17.33*0.2020*(150/1000) =-33.14kJ