Q. Find the change in concentration for a steady state equimolar counter diffusion if D(AB)= 6 sq.m/sec, the change in distance is 2 m and the N flux of A is 5 mol/sq.m sec.

View solution

Q. Find the diffusivity of AB in sq.m/sec if N flux of A 5 mol/sq.m sec, concentration difference is 2mol/cu.m and distance is 3 m.

View solution

Q. __________ energy helps for molecular diffusion.

View solution

Q. For two particles at steady state collision of A and B, J flux of A is 2 mol/sq.m sec, find the J flux of B.

View solution

Q. Estimate the mole fraction if concentration of A is 2 mol/cu.m and the total concentration is 5 mol/cu.m.

View solution

Q. Find the partial pressure of A if the total pressure is 2 atm; Concentration of A is 2 mol/cu.m and total concentration is 5 mol/cu.m.

View solution

Q. From the reaction, Methane –> Carbon + 2(Hydrogen molecule), find the ratio of N Flux of A to the Total N flux( A+B); Given N Flux of B =-2 N flux of A.

View solution

Q. For a Steady state diffusion of A through Non- diffusing B. N flux of B= ______

View solution

Q. The value of N flux of A under steady state non-diffusing B with diffusing A is _________

View solution

Q. If the value of N flux of A to the total N flux is 1 then it is a steady state diffusion of non-diffusing B.

View solution

Q. In respect to free convection over a vertical flat plate, the Nusselt number for laminar and turbulent flows varies respectively with Grashoff number G ᵣ as

View solution

Q. Experimental results indicate that the local heat transfer coefficient h g for flow over a flat plate with an extremely rough surface is approximated by the relation

hₓ = a x -0.12

Where a is a constant coefficient and x is distance from the leading edge of the plate. What is the relation between this local heat transfer coefficient and the average heat transfer coefficient for a plate of length x?

View solution

Q. For the free convection circumstances, the following dimensionless numbers apply

(i) Grashof number
(ii) Prandtl number
(iii) Nusselt number

Identify the correct answer.

View solution

Q. Two horizontal steam mains with diameters 5 cm and 15 cm are to be laid in a boiler house that any mutual heat effect is precluded. The mains are at the same surface temperature of 500 degree Celsius whilst the ambient air is at 50 degree Celsius. Workout the ratios of the heat transfer coefficients.

View solution

Q. Two horizontal steam mains with diameters 5 cm and 15 cm are to be laid in a boiler house that any mutual heat effect is precluded. The mains are at the same surface temperature of 500 degree Celsius whilst the ambient air is at 50 degree Celsius. Workout the heat losses from one meter length of the mains

View solution

Q. A spherical heater of 20 cm diameter and at 60 degree Celsius is immersed in a tank of water at 20 degree Celsius. Determine the value of convective heat transfer coefficient

View solution

Q. A steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, determine the rate of heat loss. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are

k =3.64 * 10⁻² W/m K
v =30.09 * 10⁻⁶ m²/s
P ᵣ =0.682
Β =1/160 + 273 = 2.31 * 10⁻³ per K

View solution

Q. A steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, find out the Grashof number. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are

k =3.64 * 10⁻² W/m K
v =30.09 * 10⁻⁶ m²/s
P ᵣ =0.682
Β =1/160 + 273 = 2.31 * 10⁻³ per K

View solution

Q. Estimate the heat transfer from a 40 W incandescent bulb at 125 degree Celsius to 25 degree Celsius in quiescent air. Approximate the bulb as a 50 mm diameter sphere. The approximate correlation for the convection coefficient is
Nu = 0.60 (Gr Pr)^ 0.25

Where the different parameters are evaluated at the mean film temperature, and characteristics length is the diameter of the sphere.

View solution

Q. A 40 W incandescent bulb at 125 degree Celsius to 25 degree Celsius in quiescent air. Approximate the bulb as a 50 mm diameter sphere. The approximate correlation for the convection coefficient is
Nu = 0.60 (Gr Pr)^ 0.25

Where the different parameters are evaluated at the mean film temperature, and characteristics length is the diameter of the sphere.

Find what percent of power is lost by free convection?

View solution