Design of Heat Exchanger LMTD= Omax In Bmin 24 4 = 24 In 11.1622 °C tare = [10+ [20 44.8 + 54.8 tave = 2 tave = 49.8 °C Overall Heat Transfer Coefficient Number of Tubes Average Temperature v is given as: = 0.0010120 convert the water entering the tube into volume V₁ = (WW) v Assume a feedwater velocity of V₁ = 1961.7073 ) 0.0010120 ) 2.4 m/s From tave = 49.8 °C V₁ = 1.985 And velocity= 2.4 m/s Since BWG 18 is used, thickness = 1.65 mm kj d₁ = do 2t Umra is given as = 3.6 m² - °C s d₁ = 25.4 - 2 (1.65 ) d₁ = 22.1 mm Heat Ww Exchanger Mw tave = [10+ [20 Average Temperature Temperature of Heat Exchanger 83 to 5.8 °C tave = 44.8 + 54.8 2 = 49.8 °C Efficiency 21 Use ₁ = 4 °C Mass balance on heat exchanger 82 = 5.6 to 16.7 °C Use 8₂ = 10 °C 20 54.8 °C 1944.8 °C +22=t19 - 8₁ = 44.84 = 40.8 °C 21=22 82 = 44.8- 10 30.8 °C Assume Mass of Cooling Water, m e = 90 % Corresponding Correction Factor W = 1961.71 kg/s computed Use in = 25.4 mm From the Energy-Balance Diagram Output Input €22 hot water out Arsenic-Copper Tubes BWG 18 +21 cold water out €20 hot water out Product t19 cold water out kj U = 3.6 ( 1 ) = 3.6 Ww cw (122 - 21 ) m² s = Mw = mw mcwtz0-19) W (122-121 ) e (2019) (1961.71)(40.8 30.8) 0.90 (54.8 - 44.8) For Cooling Tower mw=2179.67 kg/s Logarithmic Mean Temperature Difference Use Counter Flow to 'max = 20 21 Omax =54.8- 30.8 Omax 24 °C Omin 19t22 @max 44.8 40.8 @max= 4 °C Surface Area Required Ainside = 383.597214 mm² V₁ n = Atube v 11. = 1.9853262 (0.000383597) (2.4) Ainside = 0.000383597 m² V₁ = A v n₁ QHE = Ww Cw (t20 QHE 419) n = 2156.47879 = 2157 tubes = 1961.71 (4.187) (54.8 44.8) Que = 82136.68 В вита 82136.68 2044.0164 m² (3.6) (11.1622 ) Tube Length For BWG 18 0.07982 惟 2044.0164 L₂ = L₂ = 2157) (0.07982 11.8755 m Standard Surface Area per Unit Length Actual Number of Tube and Length of Tubes Use 8 Pass n = 2157 (8) = 17256 tubes L't = 11.8755 + 8 = 1.4844m Outside Diameter of the Shell C P_(pitch) = 150 mm = c + do = 150 + 25.4 = 175.4 mm P 6.905511811 in 166 The number of tubes per square feet of tube sheet = page 67 PGCRG P The number of tubes per square feet of tube sheet Since there are 17256 tubes 24.03876853 tubes ft² Atube sheet Atube tube sheet = 17256 24.03876853 = 717.840433 ft² = 103369.022 in² Dshell Atube sheet = = √131613.2162 in 0.7854 = Dshell D shell = 362.79 9.215 in E

Design of Heat Exchanger LMTD= Omax In Bmin 24 4 = 24 In 11.1622 °C tare = [10+ [20 44.8 + 54.8 tave = 2 tave = 49.8 °C Overall Heat Transfer Coefficient Number of Tubes Average Temperature v is given as: = 0.0010120 convert the water entering the tube into volume V₁ = (WW) v Assume a feedwater velocity of V₁ = 1961.7073 ) 0.0010120 ) 2.4 m/s From tave = 49.8 °C V₁ = 1.985 And velocity= 2.4 m/s Since BWG 18 is used, thickness = 1.65 mm kj d₁ = do 2t Umra is given as = 3.6 m² - °C s d₁ = 25.4 - 2 (1.65 ) d₁ = 22.1 mm Heat Ww Exchanger Mw tave = [10+ [20 Average Temperature Temperature of Heat Exchanger 83 to 5.8 °C tave = 44.8 + 54.8 2 = 49.8 °C Efficiency 21 Use ₁ = 4 °C Mass balance on heat exchanger 82 = 5.6 to 16.7 °C Use 8₂ = 10 °C 20 54.8 °C 1944.8 °C +22=t19 - 8₁ = 44.84 = 40.8 °C 21=22 82 = 44.8- 10 30.8 °C Assume Mass of Cooling Water, m e = 90 % Corresponding Correction Factor W = 1961.71 kg/s computed Use in = 25.4 mm From the Energy-Balance Diagram Output Input €22 hot water out Arsenic-Copper Tubes BWG 18 +21 cold water out €20 hot water out Product t19 cold water out kj U = 3.6 ( 1 ) = 3.6 Ww cw (122 - 21 ) m² s = Mw = mw mcwtz0-19) W (122-121 ) e (2019) (1961.71)(40.8 30.8) 0.90 (54.8 - 44.8) For Cooling Tower mw=2179.67 kg/s Logarithmic Mean Temperature Difference Use Counter Flow to 'max = 20 21 Omax =54.8- 30.8 Omax 24 °C Omin 19t22 @max 44.8 40.8 @max= 4 °C Surface Area Required Ainside = 383.597214 mm² V₁ n = Atube v 11. = 1.9853262 (0.000383597) (2.4) Ainside = 0.000383597 m² V₁ = A v n₁ QHE = Ww Cw (t20 QHE 419) n = 2156.47879 = 2157 tubes = 1961.71 (4.187) (54.8 44.8) Que = 82136.68 В вита 82136.68 2044.0164 m² (3.6) (11.1622 ) Tube Length For BWG 18 0.07982 惟 2044.0164 L₂ = L₂ = 2157) (0.07982 11.8755 m Standard Surface Area per Unit Length Actual Number of Tube and Length of Tubes Use 8 Pass n = 2157 (8) = 17256 tubes L't = 11.8755 + 8 = 1.4844m Outside Diameter of the Shell C P_(pitch) = 150 mm = c + do = 150 + 25.4 = 175.4 mm P 6.905511811 in 166 The number of tubes per square feet of tube sheet = page 67 PGCRG P The number of tubes per square feet of tube sheet Since there are 17256 tubes 24.03876853 tubes ft² Atube sheet Atube tube sheet = 17256 24.03876853 = 717.840433 ft² = 103369.022 in² Dshell Atube sheet = = √131613.2162 in 0.7854 = Dshell D shell = 362.79 9.215 in E

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.53P

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