10.1 lecture


Problem: Air enters a 5 cm diameter insulated tube at 500 kPa, 300K, with a velocity of 20 m/s. At the exit the pressure is 200 kPa due to frictional losses. Determine (a) the exit velocity and (b) the rate of entropy generation in the system. (c) What would be the exit velocity if the change in ke is neglected?





Solution:
#----To save the analysis, copy everything in this input area (TEST-codes and User-Codes) into a local text file.
#	Path: Home>TESTapps>Open>Generic>Single-Flow>PG-Model;  V: iu
#----To reproduce the solution, launch this TESTapp (note pathname above), paste the codes here, and click Load.

   States {
      State-1: Air; PG-Model;
      Given: {p1 = "p1kPa" kPa; T1 = "T1K" K; Vel1 = "Vel1mps" m/s; z1 = 0.00 m; A1 = "Acm2" cm^2; }

      State-2: Air; PG-Model;
      Given: {p2 = "p2kPa" kPa; z2 = 0.00 m; j2 = "j1" kJ/kg; mdot2 = "mdot1" kg/s; A2 = "A1" mm^2; }
   }

   Devices {
      Device-1: Single-Flow; 1-2;
      Given: {Qdot1 = 0.00 kW; WdotExt1 = 0.00 kW; TB1 = 298.150 K; }
   }
      
#----User-codes block (do not alter this comment line).;

#----given info: let state-1 be the inlet and 2 be the exit.;
      dcm=5;
      p1kPa = 500;
      T1K = 300;
      Vel1mps = 20;
      p2kPa = 200;
#----mass, energy and entropy equations: mdot1 = mdot2; j1= j2; s2 = s1 + Sdot_gen/mdot;
      Acm2 = pi*dcm^2/4;
#-----part (a)
Velmps = Vel2;
#-----part (b)
SdotGenkWpK = SdotGen1;