VENTILATION ASSIGNMENT

Ventilation assignment

Ventilation assignment

Question number 01

Solution

Volumetric flow is given by

Q = V X A

Where,

A = Area = pr2 = (0.5)2 = 0.785m2

V = Velocity = 3.0m/s

Q = Volumetric flow

Q = 3 x 0.785 = 2.355 m3/s

Mass flow rate is given by

M = Q x ?

M = 2.355 x 1.2

M = 2.826 kg/s

Question number 02

Solution

Volumetric flow is given by

Q = V X A

Where,

A = Area = 14.5m2

V1 = Velocity = 231/100 = 2.31m/s

V2 = 2.45m/s

V3 = 2.38m/s

V4 = 2.28m/s

Q = Volumetric flow

Q1 = 2.31 x 14.5 = 33.495 m3/s

Q2 = 2.45 x 14.5 =35.525 m3/s

Q3 = 2.38 x 14.5 = 34.51 m3/s

Q4 = 2.28 x 14.5 = 33.06 m3/s

Qavg = (Q1+Q2+Q3+Q4)/4 = 34.147

Mavg = ? x Qavg = 34.147 x 1.2 = 40.977 kg/s

Question number 03

Solution

Concentration of methane = 0.85%

Velocity of air stream = 22.5 m/s

Volumemethane = 1 x 0.85% = 0.0085 x 22.5 = 0.191 m3/ltr

Question number 04

Solution

Q = x ? x v2

Where,

Q = Dynamic Pressure

? = density of air

V = velocity of air

650 = x 1.2 x V

V = 1083.33 m/s

Question number 05

Solution

A suitable anemometer and a stopwatch are required to make a measurement. If a stopwatch is not available, a watch which measures in seconds is acceptable. It is easier to perform a measurement with two people - one to perform the traverse and one to operate the stopwatch - but it can be accomplished by one person. Normally, the timing period for a traverse is one minute (to make subsequent calculations easier), but any convenient time period is acceptable.

Measuring air velocity with a rotating vane anemometer involves the following:

(1) Stop the vanes and “zero” the anemometer dial with the appropriate levers.

(2) Position the instrument at a corner (wall/floor or wall/roof) where the velocity is slowest.

(3) Allow the anemometer to reach full speed (a few seconds), and simultaneously start the stopwatch, release the vanes, and begin the traverse.

(4) Simultaneously stop the stopwatch and the vanes at the end of the traverse.

(5) Record the anemometer dial reading and the elapsed time from the stopwatch.

(6) Repeat the above steps. If either traverse was not fully completed, do not use that measurement. Repeat the above steps until two good traverses are completed that agree to within 5 %. Again, this is easiest if the time period is constant at one minute. The resulting two readings would then be averaged.

(7) If split traverses were performed, repeat the above steps for the other half of the air course.

(Metal/Nonmetal Health Inspection Procedures Handbook PH06-IV-1(1) October 2006 18-10)

Question number 06

Method 1: Direct Application of the Steady Flow Energy Equation

Subsurface Ventilation and Environmental Engineering (McPherson 1993, Section 6.3) provides the

Following procedure for reduction of the data taken during a barometric pressure survey. Equation 1

(Steady Flow Energy Equation) is used evaluate the work done against friction as the air travels between two stations.

Where: F - Work done against friction (J/kg)

P - Barometric pressure ...