dgau008
Mechanical
- Dec 21, 2011
- 11
hi
i am doing a project where i need to measure the flow rate of hot flue gasses (co, co2, nitrogen). i have took the pressure inside the heat exchanger mounted on fireplace rather than having flow velocity. then i use bernoullis equation as following to get flow rate.
Dia of pipe= 51mm
inner dia = 38mm
Corrugated pipe
pressure 300 pa
to find velocity from pressure (Bernoulli equation):
(po + p1) + rho v1^2 / 2 = (po + p2) + rho v2^2 / 2
where
p - pressure
v - velocity
1 and 2 subscripts indicate initial and exit values, while po is atmospheric pressure
(there is no height term since the pipe is horizontal)
if we assume that v1 = 0, and p2=0 (pipe exit)
v2 = sqrt (2 p1 / rho)
where p1 = 300 Pa
rho = 1000 kg/m^3
v2 = 0.77 m/s
Flow rate:
Q = A v2 = (25.5^2 pi / 4) * 0.77 = 393 m^3/s
result seems to me so weierd. it should not be so much high. can any one have any idea where i went wrong or the results are good enough.
thanks
i am doing a project where i need to measure the flow rate of hot flue gasses (co, co2, nitrogen). i have took the pressure inside the heat exchanger mounted on fireplace rather than having flow velocity. then i use bernoullis equation as following to get flow rate.
Dia of pipe= 51mm
inner dia = 38mm
Corrugated pipe
pressure 300 pa
to find velocity from pressure (Bernoulli equation):
(po + p1) + rho v1^2 / 2 = (po + p2) + rho v2^2 / 2
where
p - pressure
v - velocity
1 and 2 subscripts indicate initial and exit values, while po is atmospheric pressure
(there is no height term since the pipe is horizontal)
if we assume that v1 = 0, and p2=0 (pipe exit)
v2 = sqrt (2 p1 / rho)
where p1 = 300 Pa
rho = 1000 kg/m^3
v2 = 0.77 m/s
Flow rate:
Q = A v2 = (25.5^2 pi / 4) * 0.77 = 393 m^3/s
result seems to me so weierd. it should not be so much high. can any one have any idea where i went wrong or the results are good enough.
thanks
