Duct Segment Identification: AC

Duct Segment Identification: AC

• Target Volumetric Flow rate (Design) Q = 390cfm (Given)
• Minimum Transport Velocity (Vt) = 4000 fpm (Given)
• Maximum Duct Diameter = 4.22”

Q = V * A

A = Q / V

= 390 / 4000 = 0.375 Sq. ft

A = (Pi * D2)/ 4

Hence D = 4.22”

• Selected Duct Diameter = 4”

We don’t have a diameter of 4.22”. Let’s choose a diameter that is less than the obtained one and is available.

• Duct Area = 0.087 sq. ft.

By taking diameter = 4”

• Actual Duct Velocity = 4467 fpm

V = Q / Duct Area = 390 / 0.087

• Duct Velocity Pressure, VP = 1.24” wg

We know VP = (V / 4005)2

• Maximum Slot Area = N / A
• Slot Area Selected = N / A
• Slot Velocity Pressure = N / A
• Slot Loss Coefficient = N / A
• Acceleration Factor = N / A
• Slot Loss per VP = N / A
• Slot Static Pressure = N / A
• Duct Entry Loss Coefficient = 0.65

For θ = 1800 and rectangular hood loss factor = 0.65 from FIGURE 5-15

• Acceleration Factor = 1

Acceleration Factor is generally taken as 1 for hoods.

• Duct Entry Loss per VP = 1.65

Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor

• Duct Entry Loss = 2.046

Duct Entry Loss = Duct Entry Loss per VP * Duct VP

• Other Losses = N / A

Hood Static Pressure (SPh) = 2.046

• Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss + Other Losses
• Straight Duct Length = 15’ (Given)
• Friction Factor (Hf) = 0.0703

From TABLE 5-5 at V = 4000 fpm and D = 8”

Friction Loss per VP = 1.0545

• No. of 900 degree elbows = N / A
• Elbow Loss Coefficient = N / A

• Elbow Loss per VP = N / A
• No. of Branch Entries = N / A
• Entry Loss Coefficient = N / A
• Entry Loss per VP = N / A

Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient

• Special Fittings Loss Factors = N / A
• Duct Loss per VP = 1.0545

Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry Loss per VP + Special Fittings Loss Factors

• Duct Loss = 1. 3080

Duct Loss = Duct Loss per VP * Duct VP

• Duct SP Loss = 3.350

SP Loss = Hood Static Pressure + Duct Loss

• Other Losses = N / A
• Cumulative Static Pressure = 3.350
• Governing Static Pressure = -3.350’ wg

It is a negative pressure

• Corrected Volumetric Flow rate = N / A
• Corrected Velocity = N / A
• Corrected Velocity Pressure = N / A
• Resultant Velocity Pressure = N / A

Duct Segment Identification: BC

• Target Volumetric Flow rate (Design) Q = 390cfm (Given)
• Minimum Transport Velocity (Vt) = 4000 fpm (Given)
• Maximum Duct Diameter = 4.22”

Q = V * A

A = Q / V

= 390 / 4000 = 0.375 Sq. ft

A = (Pi * D2)/ 4

Hence D = 4.22”

• Selected Duct Diameter = 4”

We don’t have a diameter of 4.22”. Let’s choose a diameter that is less than the obtained one and is available.

• Duct Area = 0.087 sq. ft.

By taking diameter = 4”

• Actual Duct Velocity = 4467 fpm

V = Q / Duct Area = 390 / 0.087

• Duct Velocity Pressure, VP = 1.24” wg

We know VP = (V / 4005)2

• Maximum Slot Area = N / A
• Slot Area Selected = N / A
• Slot Velocity Pressure = N / A
• Slot Loss Coefficient = N / A
• Acceleration Factor = N / A
• Slot Loss per VP = N / A
• Slot Static Pressure = N / A
• Duct Entry Loss Coefficient = 0.65

For θ = 1800 and rectangular hood loss factor = 0.65 from FIGURE 5-15

• Acceleration Factor = 1

Acceleration Factor is generally taken as 1 for hoods.

• Duct Entry Loss per VP = 1.65

Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor

• Duct Entry Loss = 2.046

Duct Entry Loss = Duct Entry Loss per VP * Duct VP

• Other Losses = N / A

Hood Static Pressure (SPh) = 2.046

• Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss + Other Losses
• Straight Duct Length = 15’ (Given)
• Friction Factor (Hf) = 0.0703

From TABLE 5-5 at V = 4000 fpm and D = 8”

Friction Loss per VP = 1.0545

• No. of 900 degree elbows = N / A
• Elbow Loss Coefficient = N / A

• Elbow Loss per VP = N / A
• No. of Branch Entries = N / A
• Entry Loss Coefficient = N / A
• Entry Loss per VP = N / A

Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient

• Special Fittings Loss Factors = N / A
• Duct Loss per VP = 1.0545

Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry Loss per VP + Special Fittings Loss Factors

• Duct Loss = 1. 3080

Duct Loss = Duct Loss per VP * Duct VP

• Duct SP Loss = 3.350

SP Loss = Hood Static Pressure + Duct Loss

• Other Losses = N / A
• Cumulative Static Pressure = 3.350
• Governing Static Pressure = -3.350’ wg

It is a negative pressure

• Corrected Volumetric Flow rate = N / A
• Corrected Velocity = N / A
• Corrected Velocity Pressure = N / A
• Resultant Velocity Pressure = N / A

Duct Segment Identification: CD

• Target Volumetric Flow rate (Design) Q = 390cfm (Given)
• Minimum Transport Velocity (Vt) = 4000 fpm (Given)
• Maximum Duct Diameter = 4.22”

Q = V * A

A = Q / V

= 390 / 4000 = 0.375 Sq. ft

A = (Pi * D2)/ 4

Hence D = 4.22”

• Selected Duct Diameter = 4”

We don’t have a diameter of 4.22”. Let’s choose a diameter that is less than the obtained one and is available.

• Duct Area = 0.087 sq. ft.

By taking diameter = 4”

• Actual Duct Velocity = 4467 fpm

V = Q / Duct Area = 390 / 0.087

• Duct Velocity Pressure, VP = 1.24” wg

We know VP = (V / 4005)2

• Maximum Slot Area = N / A
• Slot Area Selected = N / A
• Slot Velocity Pressure = N / A
• Slot Loss Coefficient = N / A
• Acceleration Factor = N / A
• Slot Loss per VP = N / A
• Slot Static Pressure = N / A
• Duct Entry Loss Coefficient = 0.65

For θ = 1800 and rectangular hood loss factor = 0.65 from FIGURE 5-15

• Acceleration Factor = 1

Acceleration Factor is generally taken as 1 for hoods.

• Duct Entry Loss per VP = 1.65

Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor

• Duct Entry Loss = 2.046

Duct Entry Loss = Duct Entry Loss per VP * Duct VP

• Other Losses = N / A

Hood Static Pressure (SPh) = 2.046

• Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss + Other Losses
• Straight Duct Length = 15’ (Given)
• Friction Factor (Hf) = 0.0703

From TABLE 5-5 at V = 4000 fpm and D = 8”

Friction Loss per VP = 1.0545

• No. of 900 degree elbows = N / A
• Elbow Loss Coefficient = N / A

• Elbow Loss per VP = N / A
• No. of Branch Entries = N / A
• Entry Loss Coefficient = N / A
• Entry Loss per VP = N / A

Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient

• Special Fittings Loss Factors = N / A
• Duct Loss per VP = 1.0545

Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry Loss per VP + Special Fittings Loss Factors

• Duct Loss = 1. 3080

Duct Loss = Duct Loss per VP * Duct VP

• Duct SP Loss = 3.350

SP Loss = Hood Static Pressure + Duct Loss

• Other Losses = N / A
• Cumulative Static Pressure = 3.350
• Governing Static Pressure = -3.350’ wg

It is a negative pressure

• Corrected Volumetric Flow rate = N / A
• Corrected Velocity = N / A
• Corrected Velocity Pressure = N / A
• Resultant Velocity Pressure = N / A

Duct Segment Identification: MAIN

• Target Volumetric Flow rate (Design) Q = 390cfm (Given)
• Minimum Transport Velocity (Vt) = 4000 fpm (Given)
• Maximum Duct Diameter = 4.22”

Q = V * A

A = Q / V

= 390 / 4000 = 0.375 Sq. ft

A = (Pi * D2)/ 4

Hence D = 4.22”

• Selected Duct Diameter = 4”

We don’t have a diameter of 4.22”. Let’s choose a diameter that is less than the obtained one and is available.

• Duct Area = 0.087 sq. ft.

By taking diameter = 4”

• Actual Duct Velocity = 4467 fpm

V = Q / Duct Area = 390 / 0.087

• Duct Velocity Pressure, VP = 1.24” wg

We know VP = (V / 4005)2

• Maximum Slot Area = N / A
• Slot Area Selected = N / A
• Slot Velocity Pressure = N / A
• Slot Loss Coefficient = N / A
• Acceleration Factor = N / A
• Slot Loss per VP = N / A
• Slot Static Pressure = N / A
• Duct Entry Loss Coefficient = 0.65

For θ = 1800 and rectangular hood loss factor = 0.65 from FIGURE 5-15

• Acceleration Factor = 1

Acceleration Factor is generally taken as 1 for hoods.

• Duct Entry Loss per VP = 1.65

Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor

• Duct Entry Loss = 2.046

Duct Entry Loss = Duct Entry Loss per VP * Duct VP

• Other Losses = N / A

Hood Static Pressure (SPh) = 2.046

• Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss + Other Losses
• Straight Duct Length = 15’ (Given)
• Friction Factor (Hf) = 0.0703

From TABLE 5-5 at V = 4000 fpm and D = 8”

Friction Loss per VP = 1.0545

• No. of 900 degree elbows = N / A
• Elbow Loss Coefficient = N / A

• Elbow Loss per VP = N / A
• No. of Branch Entries = N / A
• Entry Loss Coefficient = N / A
• Entry Loss per VP = N / A

Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient

• Special Fittings Loss Factors = N / A
• Duct Loss per VP = 1.0545

Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry Loss per VP + Special Fittings Loss Factors

• Duct Loss = 1. 3080

Duct Loss = Duct Loss per VP * Duct VP

• Duct SP Loss = 3.350

SP Loss = Hood Static Pressure + Duct Loss

• Other Losses = N / A
• Cumulative Static Pressure = 3.350
• Governing Static Pressure = -3.350’ wg

It is a negative pressure

• Corrected Volumetric Flow rate = N / A
• Corrected Velocity = N / A
• Corrected Velocity Pressure = N / A
• Resultant Velocity Pressure = N / A

Duct Segment Identification: EXHAUST

• Target Volumetric Flow rate (Design) Q = 390cfm (Given)
• Minimum Transport Velocity (Vt) = 4000 fpm (Given)
• Maximum Duct Diameter = 4.22”

Q = V * A

A = Q / V

= 390 / 4000 = 0.375 Sq. ft

A = (Pi * D2)/ 4

Hence D = 4.22”

• Selected Duct Diameter = 4”

We don’t have a diameter of 4.22”. Let’s choose a diameter that is less than the obtained one and is available.

• Duct Area = 0.087 sq. ft.

By taking diameter = 4”

• Actual Duct Velocity = 4467 fpm

V = Q / Duct Area = 390 / 0.087

• Duct Velocity Pressure, VP = 1.24” wg

We know VP = (V / 4005)2

• Maximum Slot Area = N / A
• Slot Area Selected = N / A
• Slot Velocity Pressure = N / A
• Slot Loss Coefficient = N / A
• Acceleration Factor = N / A
• Slot Loss per VP = N / A
• Slot Static Pressure = N / A
• Duct Entry Loss Coefficient = 0.65

For θ = 1800 and rectangular hood loss factor = 0.65 from FIGURE 5-15

• Acceleration Factor = 1

Acceleration Factor is generally taken as 1 for hoods.

• Duct Entry Loss per VP = 1.65

Duct Entry Loss per VP = Duct Entry Loss Factor + Acceleration Factor

• Duct Entry Loss = 2.046

Duct Entry Loss = Duct Entry Loss per VP * Duct VP

• Other Losses = N / A

Hood Static Pressure (SPh) = 2.046

• Hood Static Pressure (SPh) = Slot Static Pressure + Duct Entry Loss + Other Losses
• Straight Duct Length = 15’ (Given)
• Friction Factor (Hf) = 0.0703

From TABLE 5-5 at V = 4000 fpm and D = 8”

Friction Loss per VP = 1.0545

• No. of 900 degree elbows = N / A
• Elbow Loss Coefficient = N / A

• Elbow Loss per VP = N / A
• No. of Branch Entries = N / A
• Entry Loss Coefficient = N / A
• Entry Loss per VP = N / A

Entry Loss per VP = No. of Branch Entries * Entry Loss Coefficient

• Special Fittings Loss Factors = N / A
• Duct Loss per VP = 1.0545

Duct Loss per VP = Friction Loss per VP + Elbow Loss per VP + Entry Loss per VP + Special Fittings Loss Factors

• Duct Loss = 1. 3080

Duct Loss = Duct Loss per VP * Duct VP

• Duct SP Loss = 3.350

SP Loss = Hood Static Pressure + Duct Loss

• Other Losses = N / A
• Cumulative Static Pressure = 3.350
• Governing Static Pressure = -3.350’ wg

It is a negative pressure

• Corrected Volumetric Flow rate = N / A
• Corrected Velocity = N / A
• Corrected Velocity Pressure = N / A
• Resultant Velocity Pressure = N / A

CALCULATION OF BRAKE HORSE POWER (BHP):

FAN SP = SPout - SPin - VPin

= 0.5 – (-3.103) – 1.152 = 2.451

FAN TP = SPout + VPout - SPin - VPin

= 1.152 + 0.5 – (-3.103) – 1.152 = 3.603

BHP = FAN TP * Q / (6362 * η)

Where:

η = mechanical efficiency (generally taken as 0.9)

BHP = 3.603 * 1500 / (6362 * 0.9) = 0.94