B.TECH - Semester 6 heat and mass transfer Question Paper 2020 (jan)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- What is lumped heat capacity analysis?
- What are the factors affecting thermal conductivity?
- What is difference between hydrodynamic and thermal boundary layer?
- What is the significance of Nusselt and Rayleigh's number?
- What is the difference between heat exchanger and condenser?
- What is NTU in heat exchanger?
- What is the use of fins?
- Define Fick's law of diffusion.
- What is meant by radiation shape factor?
- What is conduction shape factor? How it is related to thermal resistance? $$ (10 \times 2=20 \text { Marks }) $$
- (a) Define critical thickness of insulation. Derive an expression for critical thickness of insulation for a sphere.
- (b) A hot acid storage tank is to be constructed with 4 mm thick lead lining, an insulating brick layer and a 5 mm thick steel outer casing. The inside surface of the lead is at $95^{\circ} \mathrm{C}$ and outside temperature at $30^{\circ} \mathrm{C...
- (a) Derive an expression for the temperature distribution and heat transfer in case of a solid sphere subjected to internal heat generation and with specified surface temperature.
- (b) A nichrome wire having a resistively of 110 micro-ohm-cm is to be used as heating element. The wire diameter is 2 mm and the other design features are: Current $=25 \mathrm{~A}$, Ambient temperature $=20^{\circ} \mathrm{C}, \mathrm{k}_{\text {ich...
- (a) Show by means of dimensional analysis for forced convection heat transfer, the Nusselt number is a function of Reynolds number and Prandtl number.
- (b) Water is heated while flowing through a $1.5 \mathrm{~cm} \times 4 \mathrm{~cm}$ rectangular duct at a velocity of $1.5 \mathrm{~m} / \mathrm{s}$. Entry temperature of water is $30^{\circ} \mathrm{C}$. The wall of the duct is maintained at $80^{\...
- (a) Explain displacement, momentum and energy thickness.
- (b) The water in a $\operatorname{tank}$ at $200^{\circ} \mathrm{C}$ is heated by passing the steam through a pipe of 50 cm long and 5 cm in diameter. If the pipe surface temperature is maintained at $800^{\circ} \mathrm{C}$ find the heat loss from t...
- (a) Differentiate between (i) Nucleate and Film Boiling (ii) Film wise condensation and Drop wise condensation.
- (b) A counter-flow heat exchanger is employed to cool $0.55 \mathrm{~kg} / \mathrm{s}$ ( $C_{p}=2.45 \mathrm{kJ} / \mathrm{kg}^{\circ} \mathrm{C}$ ) of oil from $115^{\circ} \mathrm{C}$ to $40^{\circ} \mathrm{C}$ by the use of water. The inlet and ut...
- (a) Derive an expression for effectiveness by NTU method for parallel flow heat exchanger.
- (b) Two long rods of the same diameter, one made of brass ( $\mathrm{k}=85 \mathrm{~W} / \mathrm{mK}$ ) and other made of copper ( $\mathrm{k}=375 \mathrm{~W} / \mathrm{mK}$ ) have one of their ends inserted into a furnace. Both the rods are exposed ...
- (a) Derive an expression for radiation heat exchange between two concentric cylindrical gray bodies by using electrical analogy.
- (b) A cryogenic fluid flows through a long tube of 20 mm diameter, the outer surface of which is diffuse and gray ( $\epsilon_{1}=0.02$ ) at 77 K . This tube is concentric with a larger tube of 50 mm diameter, the inner surface of which is diffuse an...
- What is lumped heat capacity analysis?
- What are the factors affecting thermal conductivity?
- What is difference between hydrodynamic and thermal boundary layer?
- What is the significance of Nusselt and Rayleigh's number?
- What is the difference between heat exchanger and condenser?
- What is NTU in heat exchanger?
- What is the use of fins?
- Define Fick's law of diffusion.
- What is meant by radiation shape factor?
- What is conduction shape factor? How it is related to thermal resistance? $$ (10 \times 2=20 \text { Marks }) $$