Fourier's law of heat conduction gives the heat flow for Irregular surfaces One dimensional cases only Nonuniform temperature surfaces Two dimensional cases only TRUE ANSWER : ? YOUR ANSWER : ?
In regenerator type heat exchanger, heat transfer takes place by Flow of hot and cold fluids alternately over a surface A complete separation between hot and cold fluids Generation of heat again and again Direct mixing of hot and cold fluids TRUE ANSWER : ? YOUR ANSWER : ?
Heat transfer by radiation mainly depends upon Kind and extent of its surface All of these Its temperature Nature of the body TRUE ANSWER : ? YOUR ANSWER : ?
Depending on the radiating properties, a body will be white when (Where a = absorptivity, p = reflectivity, x = transmissivity) X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 P = 0, x = 1 and a = 0 TRUE ANSWER : ? YOUR ANSWER : ?
Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ρ = Density of fluid, cp = Specific heat at constant pressure, and μ = Coefficient of absolute viscosity) RN = hl/k RN = V²/t.cp RN = ρ V l /μ RN = μ cp/k TRUE ANSWER : ? YOUR ANSWER : ?
The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) TRUE ANSWER : ? YOUR ANSWER : ?
The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called Newton's law of heating Stefan's law Newton's law of cooling First law of thermodynamics TRUE ANSWER : ? YOUR ANSWER : ?
The product of Reynolds number and Prandtl number is known as Stanton number Grashoff number Biot number Peclet number TRUE ANSWER : ? YOUR ANSWER : ?
According to Kirchoff's law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a Red hot body Grey body Brilliant white polished body Black body TRUE ANSWER : ? YOUR ANSWER : ?