Q. Which of the following is not correct in a transient flow process?

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Q. A cylindrical stainless steel (k = 25 W/m K) ingot, 10 cm in diameter and 25 cm long, passes through a heat treatment furnace which is 5 meter in length. The initial ingot temperature is 90 degree Celsius, the furnace gas is at 1260 degree Celsius and the combined radiant and convective surface coefficient is 100 W/m² K. Determine the maximum speed with which the ingot moves through the furnace if it must attain 830 degree Celsius temperature. Take thermal diffusivity as 0.45 * 10¯⁵ m²/s

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Q. The curve for unsteady state cooling or heating of bodies is

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Q. What is the wavelength band for TV rays?

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Q. Diagram shows transient heat conduction in an infinite plane wall. Identify the correct boundary condition in transient heat conduction in solids with finite conduction.

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Q. Let there is some conduction resistance, then temperature becomes a function of
(i) Biot number
(ii)Fourier number
(iii) Dimensionless parameter
Identify the correct statement

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Q. A large steel plate 50 mm thick is initially at a uniform temperature of 425 degree Celsius. It is suddenly exposed on both sides to an environment with convective coefficient 285 W/m² K and temperature 65 degree Celsius. Determine the center line temperature.
For steel, thermal conductivity = 42.5 W/m K and thermal diffusivity = 0.043 m²/hr

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Q. “When Biot number exceeds 0.1 but is less than 100, use is made of Heislers charts for the solution of transient heat conduction”. Choose the correct answer

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Q. A 12 cm diameter cylindrical bar, initially at a uniform temperature of 40 degree Celsius, is placed in a medium at 650 degree Celsius with convective coefficient of 22 W/m² K. Determine the time required for the center to reach 255 degree Celsius. For the material of the bar:
Thermal conductivity = 20 W/m K
Density = 580 kg/m³
Specific heat = 1050 J/kg K

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Q. “A solid which extend itself infinitely in all directions of space is termed as finite solid”. Choose the correct answer

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Q. A gold ring (k = 65 W/m K) measuring 15 * 10 * 60 cm is exposed to a surface where h = 11.5 W/m² K. Find the value of biot number

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Q. In the lumped system parameter model, the variation of temperature with time is

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Q. Which of the following dimensionless number gives an indication of the ratio of internal (conduction) resistance to the surface (convective) resistance?

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Q. Lumped parameter analysis for transient heat conduction is essentially valid for

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Q. In the non-dimensional Biot number, the characteristics length is the ratio of

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Q. During heat treatment, cylindrical pieces of 25 mm diameter, 30 mm height and at 30 degree Celsius are placed in a furnace at 750 degree Celsius with convective coefficient 80 W/m² degree. Calculate the time required to heat the pieces to 600 degree Celsius. Assume the following property values
Density = 7850 kg /m³
Specific heat = 480 J/kg K
Conductivity = 40 W/m degree

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Q. The quantity h L C/k is known as

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Q. For a plat plate (thickness δ, breadth b and height h) the heat exchange occurs from both the sides. The characteristics length is equal to

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Q. Fourier number is given by

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Q. Identify the correct relation between Biot number and Fourier number

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