Q. Let us say thermal conductivity of a wall is governed by the relation k = k0 (1 + α t). In that case the temperature at the mid-plane of the heat conducting wall would be

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Q. Heat is transferred from a hot fluid to a cold one through a plane wall of thickness (δ), surface area (A) and thermal conductivity (k). The thermal resistance is

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Q. A pipe carrying steam at 215.75 degree Celsius enters a room and some heat is gained by surrounding at 27.95 degree Celsius. The major effect of heat loss to surroundings will be due to

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Q. “Radiation cannot be affected through vacuum or space devoid of any matter”. True or false

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Q. A composite slab has two layers having thermal conductivities in the ratio of 1:2. If thickness is same for each layer then the equivalent thermal conductivity of the slab would be

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Q. A composite wall of a furnace has two layers of equal thickness having thermal conductivities in the ratio 2:3. What is the ratio of temperature drop across the two layers?

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Q. Typical examples of heat conduction through cylindrical tubes are not found in

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Q. The rate of heat conduction through a cylindrical tube is usually expressed as

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Q. Logarithmic mean area of the cylindrical tube is given as

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Q. A hot fluid is being conveyed through a long pipe of 4 cm outer diameter and covered with 2 cm thick insulation. It is proposed to reduce the conduction heat loss to the surroundings to one-third of the present rate by further covering with same insulation. Calculate the additional thickness of insulation

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Q. The heat flow equation through a cylinder of inner radius r1 and outer radius r2 is desired to be written in the same form as that for heat flow through a plane wall. For wall thickness (r₂-r₁) the area will be

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Q. A cylinder of radius r and made of material of thermal conductivity k 1 is surrounded by a cylindrical shell of inner radius r and outer radius 2r. This outer shell is made of a material of thermal conductivity k 2. Net conductivity would be

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Q. For steady state and constant value of thermal conductivity, the temperature distribution associated with radial convection through a cylinder is

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Q. A cylindrical cement tube of radii 0.05 cm and 1.0 cm has a wire embedded into it along its axis. To maintain a steady temperature difference of 120 degree Celsius between the inner and outer surfaces, a current of 5 ampere is made to flow in the wire. Find the amount of heat generated per meter length. Take resistance of wire equal to 0.1 ohm per cm of length

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Q. A stainless steel tube with inner diameter₁2 mm, thickness 0.2 mm and length 50n cm is heated electrically. The entire 15 k W of heat energy generated in the tube is transferred through its outer surface. Find the intensity of current flow

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Q. The temperature distribution associated with radial conduction through a sphere is represented by

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Q. The thermal resistance for heat conduction through a spherical wall is

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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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