| THEORY & FORMULAE |
Heat exchangers are systems that transfer heat between fluid mediums. The fluids or gases in a heat exchanger can be mixed or the energy transference can go through a conductive wall that keeps them separate. Heat exchangers are found in car radiators, furnaces, refrigerators, air conditioning, space heating, refining and chemical processing systems.
Air-cooled heat exchangers typically have rectangular bundles containg several rows of tubes. The hot fluid enters at the top of the bundle, while air is blown by fans vertically upwards across the tube bank, i.e. counter current flow.
The calculator here is based on the correlations presented by Smith and Brown, and the series of equations presented by Blackwell to fit the graphs and tables of Smith and Brown. In brief, the method begins with the first equation, hinges on the iterative solution of the second equation below, and ultimately leads to the third equation, as described by Coker:
where
R = number of tube rows
U = overall heat transfer coefficient
Q = exchager duty (heat load)
Ci's = correlation constants
t1 = air outlet temperature
t2 = air inlet temperature
T1 = process fluid outlet temperature
T2 = process fluid inlet temperature
Af = face area of bundle
Vf = face velocity of air
W = tube bundle width
L = tube width
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EXAMPLE Of Input/Output
to demo data entry expectations and results; you may edit & use it as starting point