Q. The rate of conduction heat flow in case of a composite sphere is given by

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Q. The thermal resistance for heat conduction through a hollow sphere of inner radius r1 and outer radius r2 is

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Q. A spherical vessel of 0.5 m outside diameter is insulated with 0.2 m thickness of insulation of thermal conductivity 0.04 W/m degree. The surface temperature of the vessel is – 195 degree Celsius and outside air is at 10 degree Celsius. Determine heat flow per m² based on inside area

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Q. The quantity d t/Q for conduction of heat through a body i.e. spherical in shape is

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Q. A spherical vessel of 0.5 m outside diameter is insulated with 0.2 m thickness of insulation of thermal conductivity 0.04 W/m degree. The surface temperature of the vessel is – 195 degree Celsius and outside air is at 10 degree Celsius. Determine heat flow

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Q. If we increase the thickness of insulation of a circular rod, heat loss to surrounding due to

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Q. The following data pertains to a hollow cylinder and a hollow sphere made of same material and having the same temperature drop over the wall thickness

Inside radius = 0.1 m and outside surface area = 1 square meter

If the outside radius for both the geometrics is same, calculate the ratio of heat flow in the cylinder to that of sphere?

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Q. “All the factors relating to geometry of the sections are grouped together into a multiple constant called the shape factor” True or false

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Q. Shape factor for plane wall is equal to

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Q. For a prescribed temperature difference, bodies with the same shape factor will allow heat conduction proportional to

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Q. Shape factor for cylinder is

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Q. The annealing furnace for continuous bar stock is open at the ends and has interior dimensions of 0.6 m * 0.6 m * 1.5 m long with a wall 0.3 m thick all around. Calculate the shape factor for the furnace?

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Q. Shape factor for sphere is

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Q. Which is true regarding a complete rectangular furnace?

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Q. The shape factor for complete rectangular furnace is
Where a, b and c are the inside dimensions and d x is the wall thickness

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Q. For the same material and same temperature difference, the heat flow in terms of shape factor is given by

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Q. For the same amount of fabrication material and same inside capacity, the heat loss is lowest in

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Q. With variable thermal conductivity, Fourier law of heat conduction through a plane wall can be expressed as

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Q. The inner and outer surfaces of a furnace wall, 25 cm thick, are at 300 degree Celsius and 30 degree Celsius. Here thermal conductivity is given by the relation
K = (1.45 + 0.5 * 10¯⁵ t²) KJ/m hr deg

Where, t is the temperature in degree centigrade. Calculate the heat loss per square meter of the wall surface area?

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Q. A plane wall of thickness δ has its surfaces maintained at temperatures T₁ and T₂. The wall is made of a material whose thermal conductivity varies with temperature according to the relation k = k₀ T². Find the expression to work out the steady state heat conduction through the wall?

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