Recent content by jittapon

  1. J

    Thermodynamics -- piston-cylinder device with helium is compressed....

    Homework Statement A piston-cylinder device initially contains 0.5 m^3 of helium gas at 150 kPa and 20°C.Helium is now compressed in a poytropic process(Pv^n = constant) to 400 kPa and 140°C. Determine the entropy change of helium and whether this process is reversible, irreversible, or...
  2. J

    Thermodynamics -- total entropy generation during cooling of tank of water....

    Homework Statement A 0.2 m^3 steel container that has a mass of 30 kg is filled with liquid water. Initially both the steel tank and the water are at 50°C. Now heat is transferred, and the entire system (i.e., steel and water) cools to the surrounding air temperature of 25°C. Determine the...