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Thermo dynamics, energy calculations in a duct

  1. May 14, 2012 #1
    1. The problem statement, all variables and given/known data

    A duct of length 5 m at 38 Degrees inclination to horizon with a cross section dimensions of 0.3 m X 0.4 m is carrying 2 kg/s of a heavy gas at 10C and 1.2 bars and delivers the gas flow at 50C at the end of the duct to a horizontal pipe section. i) Calculate changes to all the individual forms of energy being transported in the DUCT, if Cp and Cv of the gas are 1105 J/kgK and 912 J/kgK. The horizontal section of the pipe is a divergent section with exit cross section area of 0.24 m2. ii) Calculate the mass flow rate at the exit of the divergent pipe and the speed of the flow assuming temperature remains at 50C.

    2. Relevant equations
    not a clue


    3. The attempt at a solution
    found internal energy to be 72960j
    found enthalpy to be 88400j
    work done or flow enrgy to be 15440
    cant work out kinetic energy as cannot work out the velocity
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 15, 2012 #2
    To get the velocity, set the mass flow equal to rho*A*V where rho is density, A is area, and V is velocity. Determine rho from ideal gas law. The mass flow does not change so the product of rho, A, and V is constant.
     
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