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.

x+2 because it just doubles hon so the pattern can actually tell you the expression.

so for example,

if x=2 then 2+2 is 4

if x=4 then 4+4 is 8

and so on and so forth.

i really hope that this makes sense and you out in a way hon: )

the warning light flashes for a second or two when the engine starts. if it stays on, there's must be something wrong with the coolant. you should never dare to continue driving when the light is on. pull over as soon as possible and shut the engine off.

hope this is what you're talking about