Heat transfer
Heat transfer
(OP)
I am trying to determine the amount of heat transferred from a tank of Dia. 9' x lenght 18', containing a fluid at 36 degrees F and a room kept at a temperature of 30.2 degrees F. If anybody out there knows a simple formula or possibly how to find the heat transfer coefficient it would be appreciated.
Thanks Justin
Thanks Justin





RE: Heat transfer
RE: Heat transfer
Should give you a starting point.
RE: Heat transfer
Thanks Justin
RE: Heat transfer
Where:
q=total heat transmit.,btu/hr
u=ovr-all coeff. of transfer, btu/hr/ft^2/deg.F
a=surface area of body, ft^2
t= Log mean temp. diff. hot/cold fluids.
For the estimation of "u", I take it the fluid in the tank is a liquid and the controlling resistance is a free state convection, use a u value of 1-3. If the fluid giving up heat is not a liquid or is going through a phase change and/or the system is not in a free convection state, this u value will be low.
Hope this helps.
saxon
RE: Heat transfer
Justin
RE: Heat transfer
Heat = Mass x specific heat x temperature change
all in consistent units.
Required time to cool the material down depends on the process of filling & unloading the tanks & thermal conduction properties. Is this a batch process? What fluid is it?
For conduction,the heat transfer coefficient will be mostly the air film which varies with air velocity, surface emmisivity , film position and direction of heat flow. For still air with reflective vertical surface and horizontal heat flow, R = 1.7 or U = 1/R = 0.59
For still air with reflective horizontal surface and heat flow up, R = 1.32 or U = 0.76
By the way, have you tried indexing the thermostat down to 30.2°F & checking with a temperature chart recorder to see if it holds & how long it took to drop for the current mass of products? You may be able to experimentally answer your question.