Air at 1 atm and 20 c is flowing over the top surface of a .2x.5 m thin metal foil. the air stream velocity is 100 m/s and the metal foil is heated electrically with a uniform heat fluz of 6100 W/m2. If the friction force on the metal foil surface is 0.3 N, determine the surface temperature of the metal foil. Evaluate the fluid properties at 100°C.

The surface temperature of the metal foil is 453.645 K

Explanation:

The properties of the air at 100°C and 1 atm are the follows:

ρ = density = 0.9458 kg/m³

Cp = specific heat = 1009 J/kg K

Pr = 0.7111

The surface area of the plate is equal to:

Where

W = width of the plate = 0.2 m

L = length of the plate = 0.5 m

The average friction coefficient is equal to:

Where

F = drag force = 0.3 N

V = velocity of air flow = 100 m/s

The average heat transfer coefficient is equal to:

The surface temperature is:

Where

q = heat flux = 6100 W/m²

Tα = temperature of the air = 20°C = 293 K

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods