Aheating cable is embedded in a concrete slab for snow melting. the heating cable is heated electrically with joule heating to provide the concrete slab with a uniform heat of 1200 w/ m2. the concrete has a thermal conductivity of 1.4 w/m⋅k. to minimize thermal stress in the concrete, the temperature difference between the heater surface (t1) and the slab surface (t2) should not exceed 16°c (2015 ashrae handbook—hvac applications, chapter. 51). formulate the temperature profile in the concrete slab, and determine the thickness of the concrete slab (l) so that t1 − t2 ≤ 16°c.

18.7 mm

Explanation:

Fourier's law for heat conduction on a plate is:

q = -k/t * ΔT

Where

q: heat conducted per unit of time and surface

k: thermal conductivity

t: thickness of the plate

ΔT: temperature difference

Rearranging:

t = -k/q * ΔT

t = -1.4/(-1200) * 16 = 0.0187 m = 18.7 mm (q is negative because it is heat leaving the plate)

The maximum thickness of the concrete slab is 18.7 mm.

answer:

2d

explanation:

answer:

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