What are the purpose of duct design? Nowadays, which materials are chosen for duct? Why?

In the air duct system shown in Figure 3(b), air enters at A with a static pressure of 7.5 mm of water. The branch at B is 15m long delivering 120 m³/min and the branch at C is 22.5m long delivering 140 m³/min. At the end D of the main duct, the air delivered is 200m³/min. Using friction chart and equal pressure drop method, determine the correct diameter and velocity pressures in lengths, AB, BC, CD, branch BE and CF. Consider friction losses only.

Define Dry ice. Explain the working principle of production of dry ice. Show the schematic diagram and P-h diagram.

Design the process of liquification of natural gas with neat sketch.

Calculate the sound power level of i) a whisper that emits a power 1MW ii) a rock engine that emits 0.10 MW.

What types of common materials are used in duct air conditioning system? What are their advantages?

What methods are available for duct designing? Discuss one of them.

An air duct system is provided as shown in Fig.3(c). Determine the dimensions of AB, BC and CD using equal-friction method choosing a friction rate of 0.08 mm of water per meter length of the duct. Use the following formula for friction rate:
$$\frac{P_f}{L} = \frac{2.268 \times 10^{-3} \times Q^{1.852}}{D^{4.973}} \quad \text{mm of water / m}$$
Where Q is in m³/s and D and L are in meters.

What are the purposes of ducting? What prime factors are considered for duct designing?

What are the methods available for duct designing? What materials are used for ducting?

An air duct system is provided as shown in Figure 2(c). Choosing friction rate of 0.75 mm H₂O/m length of the duct, find the diameter of section AB, BC and CD for total flow of air 10 m³/s.

Prove that the equivalent diameter for circular duct to replace rectangular duct for the same velocity of air is
$$d_e = 1.265 \left[ \frac{a^3 b^3}{a+b} \right]^{1/5}$$
where, $d_e$ = equivalent diameter for circular duct, $a$ = width of the rectangular duct, $b$= breadth of the rectangular duct.

Twenty three hundred liters of partially frozen ice cream at -4°C are entering a hardening room 3m×5m×3m high each day. Hardening is completed and the temperature of the ice cream is lowered to -28°C in 10h. The walls, including floor and ceiling are insulated with 150mm of polyurethane and overall thickness of the wall is 250mm. The ambient temperature is 32°C and the RH is 50%. Assume the average density of ice cream is 0.6 kg/L. The average specific heat below freezing is 2.1 kJ/kg-K and the average latent heat per kg is 233 kJ. Determine the average hourly load based on 18h operation.

Define Psychometry and Psychometry chart. What is the necessity of Psychometric chart? Define relative humidity, specific humidity, dry bulb temperature and wet bulb temperature.

Describe the heating and Humidification by steam injecting showing the Psychometric process and Psychometric chart.

Velocity of air chosen through a circular duct which carries standard air is 360 m/min. The size of the duct is 0.3 m diameter. If this duct is replaced by a rectangular duct of aspect ratio 1.5. Determine the size of the rectangular duct for equal friction method. When (i) the velocity of air in two ducts is same, (ii) the discharge rate through the line duct is same.