SH5107: In Smoking One Non-filter Cigarette, a Smoker Inhales 350 ml of Aerosol: Industrial Ventilation Assignment, NUS, Singapore

Question 1

A.In smoking one non-filter cigarette, a smoker inhales 350 ml of aerosol containing 20 mg of tobacco smoke particles. What is the mass concentration of cigarette smoke in mg/m³?

B

If the particles in Question (A) are unit-density spheres 0.4 micron (μ) in diameter, how many particles does the smoker inhale from one cigarette? Given: V = (4/3) π r³

C

What is the total surface area (in cm² or m²) of the amount of smoke in Question (B)?

Given: S = 4 π r²

Question 2

A

1. Determine the saturation concentration of ethyl acetate vapour in ppm in the air at 20°C, 1 atm (760 mm Hg). Convert this to mass concentration in mg/m³.

Given: Vapour pressure of ethyl acetate = 73 mm Hg at 20°C, 1 atm; MW of ethyl acetate (CH3COOC2H5) = 88.

2. Is the saturation concentration of ethyl acetate flammable at 20°C, 1 atm? Why?

Given: The lower explosive limit of ethyl acetate is 2.0 % vol and the upper explosive limit is 11.5 %vol

B

The permissible exposure level of ethyl acetate is 400 ppm. How much ethyl acetate (liquid in g or cc) must evaporate into an enclosed room measuring 4m x 5m x 2m in order to generate 400 ppm of ethyl acetate at 20°C, 1 atm? Density of ethyl acetate = 0.90 g/cm³. Assume perfect mixing.

Question 3

A

A researcher spills 10 cc (cm³) of liquid benzene onto the workbench of an enclosed laboratory-measured 5m x 4m x 3m. If the liquid is totally evaporated into the room and uniformly mixed with the room air, determine the concentration of benzene vapor in ppm at 25°C and 1 atm (760 mm Hg or 101 kPa at sea level).

Given: Density of benzene = 0.879 g/cm³, MW = 78.

B

In Question A, what will be the benzene vapor concentration in ppm if the laboratory is located at 2,000 m above the sea level where the barometric pressure is 610 mm Hg (81 kPa) and the temperature is 10°C?

Question 4

A

A spherical iron oxide particle (density = 5.2 g/cm³) is observed to settle in still air at a rate of 0.1 cm/s. Assume STP.

1. a) What is its diameter in micron (µm)?
2. b) What is its aerodynamic equivalent diameter?

B

1. Determine the settling velocity of a unit-density spherical particle of 0.3 micron (µm) diameter at STP. Given: Cunningham or slip correction factor C_c for a 0.3 µm particle is 1.567 at STP.
2. Determine the Brownian diffusion (root mean square displacement per second) of a unit-density particle of 0.3 µm diameter. Assume STP. Given: Diffusion coefficient of a unit-density spherical particle of 0.3 µm diameter is 1.23 x 10^-6 cm²/s at STP

Question 5

What is the minimum flow rate in m³/min required to transport aerosols having 200 microns (μ) diameter in a vertical exhaust duct 40 cm (15.75”) in diameter?

Given: density of the aerosols is 7.0 g/cm³.