Which of the following expresses the thermal diffusivity of a substance in terms of thermal conductivity of a substance (k), mass density (ρ) and specific heat (c)?
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A copper block and an air mass block having similar dimensions are subjected to symmetrical heat transfer from one face of the each block. The other face of the block will be reaching to the same temperature at a rate?
The outer surface of a long cylinder is maintained at constant temperature. The cylinder does not have any heat source. The temperatures in the cylinder will _________
A steam pipe is covered with two layers of insulating materials, with the better insulating material forming the outer. What is the effect on heat conducted if the two layers are interchanged?
A plane wall is 20cm thick with an area perpendicular to heat flow of 1m2 and has a thermal conductivity of 0.5W/mK. A temperature difference of 100°C is imposed across it. What is the ratio of heat flow?
An insulating material with a thermal conductivity k = 0.12W/mK is used for a pipe carrying steam. The local coefficient of heat transfer to the surrounding h = 4 W/m²K. In order to provide effective insulation, what should be the minimum outer diameter of the pipe?
A plane slab of 100mm thickness generates heat. It is observed that the temperature drop between the center and its surface to be 50°C. If the thickness is increased to 200mm the temperature difference will be ___________
As the temperature increases, the thermal conductivity of a gas ____________
Hot air at 50°C. If the forced heat transfer convection is 75 W/m²K, the heat gain rate gain rate by the plate through an area of 2m² will be _____
Which of the following non-dimensional numbers is used for transition from laminar flow to turbulent flow in the free convection?
Which non-dimensional numbers relates the thermal boundary layer and hydrodynamic boundary layer?
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