Question

A long circular aluminium rod of thermal conductivity 240 w/m.K is attached at one end to a heated wall and transfers heat by convection to a cold fluid. If the diameter of the rod is tripled, the rate of heat removal (in %) increases by

Answer 1

Answer:

sorry ma lum Nahi ha . sorry about this

Answer 2

The rate of heat removal increases by 800%

According to the formula of convection of heat, the amount of heat transfer,

Q = $H_{c\\}$ A ($T_{Hot}$ - $T_{Cold}$)

Where, T = Temperature

A = Area of the cross section = πd²/4 , d = diameter of the rod

H$_{c}$ = Convective heat transfer coefficient or, thermal conductivity = 240 W/m.K (given)

Suppose, the initial diameter of the rod = d

The final diameter of the rod = 3d

Q ∝ d²

Q₁/Q₂ = (d₁/d₂)²

⇒ Q₁/Q₂ = 1/9

∴ Q₂/Q₁ = 9

⇒ (Q₂/Q₁) - 1 = 9 - 1

⇒ (Q₂ - Q₁/Q₁) = 8

⇒ $\frac{Q_{2}-Q_{1} }{Q_{1}}$ × 100% = 800%

∴ The rate of heat removal is increased by 800%.