Heat Transfer Mechanical previous year questions with answer

Ques 31 GATE 2015 SET-2

A cylindrical uranium fuel rod of radius 5 mm in a nuclear reactor is generating heat at the rate of 4x10⁷ W/m³. The rod is cooled by a liquid (convective heat transfer coefficient 1000 W/m²-K) at 25°C. At steady state, the surface temperature (in K) of the rod is

Ques 32 GATE 2015 SET-2

If a foam insulation is added to a 4 cm outer diameter pipe as shown in the figure, the critical radius of insulation (in cm) is ________.

Ques 33 GATE 2015 SET-2

In the laminar flow of air (Pr = 0.7) over a heated plate, if δ and δ_T denote, respectively, the hydrodynamic and thermal boundary layer thicknesses, then

Ques 34 GATE 2015 SET-1

For flow of viscous fluid over a flat plate, if the fluid temperature is the same as the plate temperature, the thermal boundary layer is

Ques 35 GATE 2015 SET-1

For flow through a pipe of radius R, the velocity and temperature distribution are as follows: u(r,x) = C₁, and T(r,x) = C₂[1 - (r/R)³], where C₁ and C₂ are constants. The bulk mean temperature is given by T_m = (2/(U_mR²)) ∫₀^R u(r,x)T(r,x)rdr, with U_m being the mean velocity of flow. The value of T_m is

Ques 36 GATE 2015 SET-1

A 10 mm diameter electrical conductor is covered by an insulation of 2 mm thickness. The conductivity of the insulation is 0.08 W/m-K and the convection coefficient at the insulation surface is 10 W/m²-K. Addition of further insulation of the same material will

Ques 37 GATE 2014 SET-3

Consider a long cylindrical tube of inner and outer radii r_i and r_o, respectively, and length L and thermal conductivity k. Its inner and outer surfaces are maintained at T_i and T_o respectively (T_i > T_o). Assuming one-dimensional steady-state heat conduction in the radial direction, the thermal resistance in the wall of the tube is

Ques 38 GATE 2014 SET-3

Consider a gas turbine blade of 1 mm thickness, made of super alloy with k = 20 W/m·K. The blade is attached to a base and exposed to hot gases on the other side. The convective heat transfer coefficient between the blade and the gas is 1500 W/m²·K. If the temperature of the gas is 1200°C and that of the base is 900°C, the temperature (in °C) of the exposed surface of the blade is _______

Ques 39 GATE 2014 SET-2

For laminar forced convection over a flat plate, if the free stream velocity increases by a factor of 2, the average heat transfer coefficient

Ques 40 GATE 2014 SET-2

In a heat exchanger, it is observed that ΔT₁ = ΔT₂, where ΔT₁ is the temperature difference between the two single phase fluid streams at one end and ΔT₂ is the temperature difference at the other end. This heat exchanger is