Heat transfer

1. Dec 19, 2009

yankees26an

1. The problem statement, all variables and given/known data
The absolute value of the heat flow rate through a slab of area 0.83 m2 is 240 W. The
thickness of the slab is 1.4 cm and its thermal conductivity is 0.6 W/(m·K). If the hot surface of the slab is at 40°C find the temperature of the cold surface.

2. Relevant equations

H = -kA($$\Delta$$T/$$\Delta$$x)

H = Q/t?

3. The attempt at a solution

A = 0.83 m^2; $$\Delta$$x = 1.4; k = 0.6 W/(m·K); Thot = 40°C;

Missing H?

2. Dec 19, 2009

rock.freak667

this should be

$$\frac{dQ}{dt}=-kA \frac{d\theta}{dx}$$

or

ΔQ/Δt=-kA(Δθ/Δt)

you were given ΔQ/Δt as 240 W

3. Dec 19, 2009

yankees26an

ok so

$$\Delta$$T = ($$\Delta$$x*H)/(kA)

$$\Delta$$T = 1.2*240/0.6*0.83

$$\Delta$$T = 578 K = 305 C ?? That's way above any answer options

4. Dec 19, 2009

rock.freak667

this should be 0.014m

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