Q. A region of fluid motion near a plate in which temperature gradient exist is

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Q. Thermo-physical properties of the fluid are represented by

(i) Density
(ii) Viscosity
(iii) Specific heat
(iv) Thermal conductivity

Identify the correct option

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Q. A motor cycle cylinder consists of ten fins, each 150 mm outside diameter and 75 mm inside diameter. The average fin temperature is 500 degree Celsius and the surrounding air is at 20 degree Celsius temperature. Make calculations for the rate of heat dissipation from the cylinder fins by convection when motor cycle is stationary and convective coefficient is 6 W/m² K

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Q. Air at 20 degree Celsius flows over a flat surface maintained at 80 degree Celsius. The local heat flow at a point was measured as 1250 W/m² .Take thermal conductivity of air as 0.028 W/m K, calculate the temperature at a distance 0.5 mm from the surface

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Q. The convective heat transfer coefficient in laminar flow over a flat plate

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Q. For laminar flow over a flat plate, the average value of Nusselt number is prescribed by the relation

Nu = 0.664 (Re)^0.5 (Pr)^0.33

Which of the following is then a false statement?

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Q. For turbulent flow over a flat plate, the average value of Nusselt number is prescribed by the relation

Nu = 0.664 (Re)^0.5 (Pr)^0.33

Which of the following is then a false statement?

The average heat transfer coefficient increases as

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Q. A nuclear reactor with its core constructed of parallel vertical plates 2.25 m high and 1.5 m wide has been designed on free convection heating of liquid bismuth. Metallurgical considerations limit the maximum surface temperature of the plate to 975 degree Celsius and the lowest allowable temperature of bismuth is 325 degree Celsius. Estimate the maximum possible heat dissipation from both sides of each plate. The appropriate correlation for the convection coefficient is
Nu = 0.13 (Gr Pr)^1/3

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Q. A thin walled duct of 0.5 m diameter has been laid in an atmosphere of quiescent air at 15 degree Celsius and conveys a particular gas at 205 degree Celsius. Base your calculations on one meter length of the duct, estimate the convective coefficient of heat transfer

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Q. Free correction modulus is given by

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Q. The free convection coefficient is given by

h = C₁ d t m/l^(1 – 3m)

The value of exponent for laminar flow is

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Q. For inclined plates we multiply Grashoff number with

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Q. The free convection coefficient is given by

h = C₁ d t m/l^(1 – 3m)

The value of exponent for turbulent flow is

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Q. Which of the following is true for laminar flow?

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Q. A horizontal heated plate at 200 degree Celsius and facing upwards has been placed in still air at 20 degree Celsius. If the plate measures 1.25 m by 1 m, make calculations for the heat loss by natural convection. The convective film coefficient for free convection is given by the following empirical relation

h = 0.32 (α)^0.25 W/m² K

Where α is the mean film temperature in degrees kelvin

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Q. For laminar flow, Reynolds number must not be less than

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Q. For laminar flow, Prandtl number must be more than

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Q. Air at atmospheric pressure and 20 degree Celsius flows with 6 m/s velocity through main trunck duct of air conditioning system. The duct is rectangular in cross-section and measures 40 cm by 80 cm. Determine heat loss per meter length of duct corresponding to unit temperature difference. The relevant thermos-physical properties of air are
v = 15 * 10¯⁶ m²/s

α = 7.7 * 10¯² m²/hr

k = 0.026 W/m degree

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Q. The local film coefficient for laminar flow past a flat plate may be obtained from the correlation

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Q. For a plate of length l, an average value of Nusselt number is given by

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