131.
Thermal conductivity of air with rise in temperature

132.
Thermal conductivity of water in general with rise in temperature

134.
The thermal diffusivities for gases are generally

135.
Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be

136.
Reynolds number (RN) is given by (where h = Film coefficient, $$l$$ = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, $$\rho $$ = Density of fluid, cp = Specific heat at constant pressure and $$\mu $$ = Coefficient of absolute viscosity)

137.
An ordinary passenger aircraft requires a cooling system of capacity.

138.
A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h1, h2 and h3 respectively. The average heat transfer coefficient for the cube is

139.
Moisture would find its way into insulation by vapour pressure unless it is prevented by

140.
The ratio of surface convection resistance to the internal conduction resistance is known as

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