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Homework Help: Fluid Mechanics (Gas through a pipe)

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data
    Hot CO₂ gas enters a pipe at pressure P₁ and exits at atmospheric pressure (P₂ = 1 bar) and T₂ = 0°C. The pipe has a constant diameter D = 1 cm. The input temperature is T₁ = 100°C and the mass flow rate ṁ = 0.5 g/min. There is a significant change in mechanical energy due to friction with a loss factor of 2500 m²/s².

    Calculate the average flow velocities, input pressure and gas densities using the given data.

    V₁ = ?
    P₁ =?
    T₁ = 100°C
    ρ₁ =?

    V₂ = ?
    P₂ = 1 bar
    T₂ = 0°C
    ρ₂ = ?

    2. Relevant equations
    1. row2 = p2/RT2
    2. V= m/(row2)A
    3. Bernouliies eqn with loss.

    3. The attempt at a solution
    I followed those three equations. The problem begins when when V1 comes out as a new negative number. That's not possible. FYI - flow is from 1 to 2.

    I'm not sure where I am missing a negative sign. I dont think it can be negative considering pressure and density values.
  2. jcsd
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