1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Need a formula that combines the stack effect + venturi effect to find Q

  1. Jan 6, 2013 #1

    I'm trying to find Q for chimney/stove that looks very similar to the picture attached. I was going to use the formula below, but I realized that it does not account for the venturi effect if a chimney was conical in shape - i.e. smaller at the top vs. the base. Nor does it account for differences in the sizes of the air inlet and outlet.

    Q=CA(sq root(2gH(Ti-To)/Ti))

    Q = flue-gas flow-rate, m³/s
    A = cross-sectional area of chimney, m² (assuming it has a constant cross-section)
    C = discharge coefficient (usually taken to be 0.65–0.70)
    g = gravitational acceleration at sea level, 9.807 m/s²
    H = height of chimney, m
    Ti = absolute average temperature of the flue gas in the stack, K
    To = absolute outside air temperature, K

    I would like to know if there is a formula to find Q that would allow me to account for the following variables:

    - area of the bottom air inlet
    - area of the top outlet
    - temp inside the chimney
    - temp outside the chimney
    - height of the chimney

    Thanks in advance!!
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted