Thus, . . . the total rate of heat transfer is found by simply superimposing the heat transfer through a nongenerating plate . . . upon the heat transfer in a generating plate . . ."
Convective Boundary Conditions. The standard boundary conditions for most wall conduction problems are succinctly described by Thomas. For conduction alone, they are T at x = 0 is T1 , and T at x = L is T2. For the case with a hot(ter) fluid convecting heat into a wall, the boundary condition at x = 0 (the wet wall) is written as:
qc = qx ; hm(TF - T1) = -k dT / dx , (10)
while the second boundary condition (at x = L) is, again, T at x = L is T2. TF is the temperature of the passing fluid, T1 is the (unknown) temperature of the fluid-touching plate side, and T2 is the temperature of the inside, dry plate wall.
T1 = L / (L + k/h)(TF - T2) + T2 . (11)
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