Could you help me??
Could you help me??
(OP)
Hi all,
I'm looking for a calculation procedure to find the minimum flow through the coil and the minimum heat loss required to avoid freezing of water in the coil for a closed circuit cooling tower. as a maintance procedure during winter season
inlet water coil temperature of 50ºF, outside temperature of -10 ºF ambient with 45 MPH wind
Many thanks in advance.
I'm looking for a calculation procedure to find the minimum flow through the coil and the minimum heat loss required to avoid freezing of water in the coil for a closed circuit cooling tower. as a maintance procedure during winter season
inlet water coil temperature of 50ºF, outside temperature of -10 ºF ambient with 45 MPH wind
Many thanks in advance.





RE: Could you help me??
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RE: Could you help me??
RE: Could you help me??
Next use the film coefficient as the overall conductance to give a heat loss of
hA*delta T
Next you write the differential equation that describes the process,
rho*a*c*v*dT/dx=h*p*(T0-T)
rho density of water
a cross sectional area
p perimeter of pipe
c specific heat=1
T0=ambient temperature=
d(T-T0)/dx+ hp/rho*a*c*v[T-T0]=0
for convenience
lamda=hp/rho*a*c*v
d(T-T0)/dx+lamda*[T-T0]=0
with a solution
T-T0=(Ti-T0)exp(-x/lamda)
If we take the case of the water just reaching 32 at the outlet the solution is
32--10=(50--10)exp(-L/lambda)
42=60*exp(-L/lambda)
l= length of coil
we now take the ln of both sides
-L/lambda=Ln(42/60)=-.356
lamda=l/.356
now from the definition of lamda which contains v, you can evaluate v.
I think I gave you enough to get a good answer, but I would at least triple the velocity I get for safety reasons.
Or if you don't like differential equations, use
rho*a*c*v*deltaT= Lph(T0-50)
rho*a*c*v*(32-50)=T0-50=-60
get v from this.
conservative but not as accurate as the ODE.
RE: Could you help me??