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GATE 2020: Heat Transfer Quiz 1
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Question 1
Heat transfer through a composite wall is shown in figure. Both the sections of the wall have equal thickness (l). The conductivity of one section is k and that of the other is 2k. The left face of the wall is at 600 K and the right face is at 300 K.
The interface temperature Ti (in K) of the composite wall is
The interface temperature Ti (in K) of the composite wall is
Question 2
A composite wall is formed of a 5 cm copper plate, a 3.5 mm layer of asbestos, and a 4 cm layer of fiberglass. The wall is subjected to an overall temperature difference of 510 °C. Calculate the heat flow per unit area through the composite structure. Thermal conductivity of copper, asbestos and fiber glass are 370, 0.4 and 1.5 W/m °C respectively.
Question 3
A plane wall 0.30 m thick generates heat uniformly at the rate of 5 × 104 W/m3. The convective heat transfer coefficient between each face of the wall and the ambient air is 50 W/m2K. Assume the ambient air temperature to be 25
, the walls have same temperature on both the sides & the thermal conductivity of the wall material to be 25 W/m K. The maximum temperature (
) in the wall is
, the walls have same temperature on both the sides & the thermal conductivity of the wall material to be 25 W/m K. The maximum temperature () in the wall is Question 4
A sphere of mass 5.5 kg and initially at a temperature of 290 K is suddenly emerged in a liquid of 15 K and convective heat transfer coefficient is 58 W/m2K. Estimate the time(in minutes) required to cool the sphere to 95K and the given properties are
ρ = 2700kg/m3, C= 900J/kg and k=205W/m K r=4.5 mm
ρ = 2700kg/m3, C= 900J/kg and k=205W/m K r=4.5 mm
Question 5
A cylindrical uranium fuel rod of radius 5 mm in a nuclear reactor is generating heat at the rate of 4 × 107 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
Question 6
A fin has 5mm diameter and 100mm length. The thermal conductivity of fin material is 400Wm−1K−1. One end of the fin is maintained at 130 ºC and its remaining surface is exposed to ambient air at 30 ºC. if the convective heat transfer coefficient is 40Wm-2K-1, the heat loss (in W) from the fin is
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Oct 13ESE & GATE ME
