i want to make a program that realistically boils water with all the variables but know near nothing about the math

i got the energy transfer equation down

but this seems to be giving me some trouble or more specifically the "convective heat transfer coefficient" http://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html

i would assume i would use this http://www.engineeringtoolbox.com/overall-heat-transfer-coefficient-d_434.html but i dont understand how to use the formula

like is it "1 / U (A) = what ever" or "(1 / U A) = what ever" and what are the little down numbers on A and h?


In practice, the equation is somewhat simpler than that given in your second link. The overall heat transfer coefficient, or U, is a combination of all of the individual heat transfer coefficients and thermal conduction through a tube wall. When these are combined, you end up with the equation

$${Q} = {U}{A}\Delta{T}$$, where the $\Delta{T}$ term is the log-mean temperature difference (see http://www.engineeringtoolbox.com/arithmetic-logarithmic-mean-temperature-d_436.html).

Other variables:

Q - heat transferred, BTU

U - heat transfer coefficient, BTU/hr-ft^2-degF

A - area through which the heat transfer is taking place

$\Delta{T}$ - log mean temperature difference, deg F

If you are simulating the boiling of water in a heat exchanger, use this equation. A real-world estimate for U of 200 BTU/hr-ft^2-degF should get you in the ball park.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.