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Industrial Ventilation

Industrial Ventilation. Design Procedure. Industrial Ventilation Design Procedure. Find Q Determine d Calculate actual V Calculate VP Find VP loss coefficients Calculate Fan SP Calculate Fan TP Choose Fan rpm from Fan Table. Losses. Inches of water Percent of velocity pressure

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Industrial Ventilation

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  1. Industrial Ventilation Design Procedure

  2. Industrial Ventilation Design Procedure • Find Q • Determine d • Calculate actual V • Calculate VP • Find VP loss coefficients • Calculate Fan SP • Calculate Fan TP • Choose Fan rpm from Fan Table Design Procedure

  3. Losses • Inches of water • Percent of velocity pressure • Friction losses • Elbow losses • Other losses • Hood entry losses • Orifice losses • Expansion and Contraction losses • Air cleaner losses • Stack losses Design Procedure

  4. Review Of Design Tables • Refer to FIGURE 5-15 to find hood entry loss coefficients. • Refer to FIGURE 5-16 to find elbow losses. • Refer to TABLE 5-5 and TABLE 5-6 to find friction loss for the given diameter and velocity. • Refer to TABLE 5-7A and TABLE 5-7B to find velocity for a given VP. • Refer to TABLE 5-8 to find area for a given diameter. • Refer to TABLE 5-10 to find Air Density Correction Factor for a given temperature and barometric pressure. • Review rest of the tables given in chapter 5. Design Procedure

  5. Review Of Design Tables • For solving various problems given in chapter # 5 the corresponding figures are given in chapter # 10. • For solving design problem 4, tables 10.70.1 to 10.70.4 will be useful. • Before solving the design problems go through the figure and data given in chapter 10. Design Procedure

  6. Review Of Design Tables • Refer to TABLE 3-1 to find the various ranges of capture velocities. • Refer to TABLE 3-2 to find the range of minimum duct velocities for various contaminants. • Go through all the figures in chapter # 3 representing various hoods. Design Procedure

  7. Design Procedure • GIVEN DATA: • Ventilation system: • Laboratory Hood • Volumetric Flow Rate, Q = 1500 CFM • Minimum Transport Velocity, V = 4000 FPM • Stamped elbow with R / D = 2 Design Procedure

  8. Design Procedure • Download DESIGN PROBLEM-1 • Line 1: Inlet Section • Line 2: Target Volume Flow Rate, Q = 1500 CFM (Given). • Line 3: Minimum Transport Velocity, V = 4000 FPM (Given). • Line 4: Maximum Duct Diameter, D = 8.29” We know Q = V * A Hence Duct Area = Q / A = 1500 / 4000 = 0.375 Sq. Ft. We know A = (Pi * D2) / 4 Hence, D = 8.29” Design Procedure

  9. Design Procedure • Line 5: Selected duct diameter = 8” We got Maximum Duct Diameter D = 8.29” We have to choose a diameter that is less than maximum selected diameter so that minimum transport velocity is not maintained in the duct. So, let’s choose 8” diameter. Note: Your choice is limited by the sizes given in the table. • Line 6: Duct Area = 0.349 Sq. ft. Duct Area (from TABLE 5-8 at D = 8”) = 0.349 Sq. ft. • Line 7: Actual Duct Velocity = 4298 FPM Velocity = Q / Area = 1500 / 0.349 = 4928 fpm Design Procedure

  10. Design Procedure • Line 8: Duct Velocity Pressure = 1.15” WG Duct VP (from TABLE 5-7A at V = 4298 FPM) = 1.15” WG • Line 9-16 = N/A (since there are no slots) • Line 17: Duct Entry Loss Coefficient = 0.49 Given, hood has a flanged duct end From TABLE 5-15 for a hood that has a flanged duct end, entry loss coefficient is 0.49 Design Procedure

  11. Design Procedure • Line 18: Acceleration Factor ( 1 or 0) = 1 Since acceleration factor is 1 for hoods. • Line 19: Duct Entry Loss per VP (17 + 18) = 1.49” WG • Line 20: Duct Entry Loss (8 * 19) = 1.714 • Line 21: Other Losses = 0 • Line 22: Hood Static Pressure, SPh (16+20+21) = 1.714” WG • Line 23: Straight Duct Length = 35 ft (Given) • Line 24: Friction Factor (Hf) = 0.0304 From TABLE 5-5 at D = 8” and V = 4000 FPM Hf = 0.0304 • Line 25: Friction Loss per VP (23 * 24) = 1.064 • Line 26: No. of 900 degree Elbows = 1 Design Procedure

  12. Design Procedure • Line 27: Elbow Loss Coefficient = 0.13 From TABLE 5-16 for a stamped elbow and R/D = 2 • Line 28: Elbow Loss Factor (26 * Loss Factor(27)) = 0.13 • Line 28-32 = N/A Since there are no branch entries • Line 33: Duct Loss per VP (25 + 28 + 31+ 32) = 1.1940 • Line 34: Duct Loss (8 * 33) = 1.3731 • Line 35: Duct Segment SP Loss (22 + 34) = 3.087” WG • Line 36: Other Losses = N / A • Line 37: Cumulative Static Pressure = 3.087” WG • Line 38: Governing Static Pressure = -3.087” WG Design Procedure

  13. Design Procedure • Line 39-42 = N / A • Line 1: Outlet Section • Line 2-8 same as for inlet section • Line 9-22 = N / A as outlet is exhaust that is it will not have suction part • Line 23: Straight Duct Length = 10 ft (Given) • Line 24: Friction Factor (Hf) = 0.0304 From TABLE 5-5 at D = 8” and V = 4000 FPM Hf = 0.0304 • Line 25: Friction Loss per VP (23 * 24) = 0.3019 • Line 26: No. of 900 degree Elbows = 1 Design Procedure

  14. Design Procedure • Line 27: Elbow Loss Coefficient = 0.13 From TABLE 5-16 for a stamped elbow and R/D = 2 • Line 28: Elbow Loss Factor (26 * Loss Factor(27)) = 0.13 • Line 28-32 = N/A Since there are no branch entries • Line 33: Duct Loss per VP (25 + 28 + 31+ 32) = 0.4319 • Line 34: Duct Loss (8 * 33) = 0.4990 • Line 35: Duct Segment SP Loss (22 + 34) = 0.499” WG • Line 36: Other Losses = N / A • Line 37: Cumulative Static Pressure = 0.499” WG • Line 38: Governing Static Pressure = -0.499” WG Design Procedure

  15. Design Procedure Final Calculations: • The Fan SP = Spo – SPin - VPin = 0.499 – (-3.087) – 1.15 = 2.436 FPM • The Fan TP = VPo + SPo – SPin - VPin = 1.15 + 0.499 – (-3.087) – 1.15 = 3.586 FPM • BHP = (Fan TP * Q) / 6362 * η = (3.586 * 1500) / (6362 * 0.9) = 0.94 hp Where: η = Mechanical Efficiency (here taken as 0.9) You have completed the design of laboratory hood. Design Procedure

  16. Design Problems • Download DESIGN PROBLEM –2, 3, 4 and start doing the problems • All are of the same procedure with minor changes. • For fan pressure calculations refer 5.8 in the text book. • Refer 5.9 to know the corrections for velocity changes. • Refer 5.13 in the text book to get an idea of corrections for non-standard density. • Go through various problems given in the text book. Design Procedure

  17. CALCULATION OF Vpr • For design problems 3 and 4 you need to calculate corrected volumetric flow rate and VPr. • For calculating corrected volumetric flow rate and VPr formulae are given in the design spread sheets. • Refer to the spread sheet solution and word solution given carefully. Design Procedure

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