Equation from Btu/ft/hr to Temperature Lloss 1

[Donkin]

I need to calculate the temperature loss when I remove the insulation from various pipework systems. I have a calculator from 3E Plus which gives an output in 610 Btu/hr/ft and I want to convert that back to a temperature loss.

I have
Specific Heat Capacities of the various fluids in the system
Flow rates of various fluids
Inlet and ambient Temperatures

Any help would be appreciated

 

[MintJulep]

specific heat is BTU / (pound x degree)

You'll need the fluid density to figure how much fluid by mass is in each foot of pipe.

You'll need the velocity to figure how long the fluid spends in the pipe.

Move things around and throw in some 60s in various places until the only units left are temperature.

 

[TD2K]

You know the heat loss from the system which is 'made up' by the cooling of the fluids in the pipe.

If Q is the heat loss from 3E or whatever program, then for a single phase liquid, the temperature drop can be estimated from:

Q = mCpdT where

m is the mass flow rate
Cp is the heat capacity
dT is the temperature drop.

If you have a phase change then you can use the latent heat to estimate how much of the vapor will condense to 'supply' the heat loss to the ambient surroundings.

 

[mraza83]

there are a few things more you need to find. For starters you should know what the coefficient of thermal conduction is (k) and the convection coeffient(h).

You definintely also need to know whether the flow is laminar or turbulent, fully developed or not (the pipe network is long, yes? if so it is likely fully developed). Hit me back when you know and i will be happy to help you.

Re = density*velocity*diameter/(dynamic viscosity)
or
Re = velocity*diameter/(kinematic viscosity)

if Re >2300 it is turbulent <2300 then it is laminar.