Q. Air flows through a 10 cm internal diameter tube at the rate of 75 kg/hr. Measurements indicate that at a particular point in the tube, the pressure and temperature of air are 1.5 bar and 325 K whilst the tube wall temperature is 375 K. Find heat transfer rate from one meter length in the region of this point
The general non-dimensional correlation for turbulent flow in the tube is

Nu = 0.023 (Re)^0.8 (Pr)^0.4

Where the fluid properties are evaluated at the bulk temperature

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Q. The ratio of inertia force to viscous force is known as

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Q. Velocity within the given fields would be similar in magnitude, direction and turbulence pattern when

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Q. Reynolds number is given by the quantity
(Where,
p is density
δ is viscosity
V is volume
l is length)

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Q. Air enters a rectangular duct measuring 30 cm by 40 cm with a velocity of 8.5 m/s and a temperature of 40 degree Celsius. The flowing air has a thermal conductivity 0.028 W/m K, kinematic viscosity 16.95 * 10¯⁶ m²/s and from empirical correlations the Nusselt number has been approximated to be 425. Find out the flow Reynolds number

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Q. For laminar flow, Reynolds number should be

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Q. For turbulent flow, Reynolds number must be

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Q. What is the value of convective coefficient of air and superheated steam in case of forced convection?

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Q. Heat is being transferred by convection from water at 48 degree Celsius to glass plate whose surface is exposed to water at 40 degree Celsius. The thermal conductivity of water is 0.6 W/m K and the thermal conductivity of glass is 1.2 W/m K. The spectral gradient of temperature in the water at the water glass interface is 10¯⁴ K/m. The heat transfer coefficient in W/m² K is

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Q. For transient flow, the value of Reynolds number may vary between

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Q. A hot plate of 15 cm² area maintained at 200 degree celsius is exposed to still air at 30 degree Celsius temperature. When the smaller side of the plate is held vertical, convective heat transfer rate is 15 per cent higher than bigger side of the plate is held vertical. Find size of the plate. The appropriate correlation for the convection coefficient is

Nu = 0.60 (Gr Pr)^0.25

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