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coefficient U using the Log Mean Temperature Difference (LMTD) method.

coefficient U using the Log Mean Temperature Difference (LMTD) method.

Introduction to Chemical Engineering Thermodynamics
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Heat Transfer Question 

Problem 2. water from 24 °C to 50 °C at a rate of 4 kg/s. Hot air is used to heat water. The air enters and exits the exchanger at 100 °C and 54 °C, respectively and it has a mass flow rate of 9.4 kg/s. Calculate the overall heat transfer coefficient U using the Log Mean Temperature Difference (LMTD) method. Note: Please use the following tables for the thermophysical properties of air and water. ,Consider a parallel-flow double pipe heat exchanger with an area of 50 m² operating to heat u· 10 ("s/m-א) v• 106 (m²/s) k• 10 (W/m K) a·106 (m²/s) T (К) (kg/m') (k J/kg K) Pr Air, M = 28.97 kg/kmol 3.5562 2.3364 1.7458 1.3947 1.1614 1.032 1.012 1.007 1.006 2.54 5.84 10.3 15.9 22.5 0.786 0.758 0.737 0.720 0.707 71.1 103.4 100 150 200 250 300 132.5 159.6 184.6 2.00 4.426 7.590 11.44 15.89 9.34 13.8 18.1 22.3 26.3 1.007 0.9950 0.8711 0.7740 208.2 20.92 26.41 0.700 0.690 0.686 0.684 350 1.009 30.0 29.9 33.8 37.3 40.7 43.9 38.3 47.2 56.7 66.7 400 1.014 230.1 250.7 270.1 288.4 450 500 550 0.6964 0.6329 1.021 1.030 32.39 38.79 45.57 1.040 0.683 TABLE A.6 Thermophysical Properties of Saturated Water" Specie Volume (m/kg) Heat of Vapor- ization, h. (kJ/kg) Specic Heat (k.J/kg · K) Thermal Viscosity (N s/m³) Conductivity (W/m K) Prandtl Number Tempera- ture, T (К) Pressure, P (bars) v • 10' µ · 10 P, 10 k• 10 k,· 10 Pr Pr. 273.15 0.00611 1.000 206.3 2502 4.217 1.854 1750 8.02 569 18.2 12.99 0.815 275 0.00697 1.000 181.7 2497 4.211 1.855 1652 8.09 574 18.3 12.22 0.817 280 0.00990 1.000 130.4 2485 4.198 1.858 1422 8.29 582 18.6 10.26 0.825 285 0.01387 1.000 99.4 2473 4.189 1.861 1225 8.49 590 18.9 8.81 0.833 290 0.01917 1.001 69.7 2461 4.184 1.864 1080 8.69 598 19.3 7.56 0.841 295 0.02617 1.002 51.94 2449 4.181 1.868 959 8.89 606 19.5 6.62 0.849 300 0.03531 1.003 39.13 2438 4.179 1.872 855 9.09 613 19.6 5,83 0.857 305 0.04712 1.005 29.74 2426 4.178 1.877 769 9.29 620 20.1 5.20 0.865 310 0.06221 1.007 22.93 2414 4.178 1.882 695 9.49 628 20.4 4.62 0,873 315 0.08132 1.009 17.82 2402 4.179 1.888 631 9.69 634 20.7 4.16 0.883 320 0.1053 1.011 13.98 2390 4.180 1.895 577 9.89 640 21.0 3.77 0.894 325 0.1351 1.013 11.06 2378 4.182 1.903 528 10.09 645 21.3 3.42 0.901 330 0.1719 1.016 8.82 2366 4.184 1.911 489 10,29 650 21.7 3.15 0.908 335 0.2167 1.018 7.09 2354 4.186 1.920 453 10.49 656 22.0 2.88 0.916 340 0.2713 1.021 5.74 2342 4.188 1.930 420 10.69 660 22.3 2.66 0.925 4
Transcribed Image Text:Problem 2. water from 24 °C to 50 °C at a rate of 4 kg/s. Hot air is used to heat water. The air enters and exits the exchanger at 100 °C and 54 °C, respectively and it has a mass flow rate of 9.4 kg/s. Calculate the overall heat transfer coefficient U using the Log Mean Temperature Difference (LMTD) method. Note: Please use the following tables for the thermophysical properties of air and water. ,Consider a parallel-flow double pipe heat exchanger with an area of 50 m² operating to heat u· 10 ("s/m-א) v• 106 (m²/s) k• 10 (W/m K) a·106 (m²/s) T (К) (kg/m') (k J/kg K) Pr Air, M = 28.97 kg/kmol 3.5562 2.3364 1.7458 1.3947 1.1614 1.032 1.012 1.007 1.006 2.54 5.84 10.3 15.9 22.5 0.786 0.758 0.737 0.720 0.707 71.1 103.4 100 150 200 250 300 132.5 159.6 184.6 2.00 4.426 7.590 11.44 15.89 9.34 13.8 18.1 22.3 26.3 1.007 0.9950 0.8711 0.7740 208.2 20.92 26.41 0.700 0.690 0.686 0.684 350 1.009 30.0 29.9 33.8 37.3 40.7 43.9 38.3 47.2 56.7 66.7 400 1.014 230.1 250.7 270.1 288.4 450 500 550 0.6964 0.6329 1.021 1.030 32.39 38.79 45.57 1.040 0.683 TABLE A.6 Thermophysical Properties of Saturated Water" Specie Volume (m/kg) Heat of Vapor- ization, h. (kJ/kg) Specic Heat (k.J/kg · K) Thermal Viscosity (N s/m³) Conductivity (W/m K) Prandtl Number Tempera- ture, T (К) Pressure, P (bars) v • 10' µ · 10 P, 10 k• 10 k,· 10 Pr Pr. 273.15 0.00611 1.000 206.3 2502 4.217 1.854 1750 8.02 569 18.2 12.99 0.815 275 0.00697 1.000 181.7 2497 4.211 1.855 1652 8.09 574 18.3 12.22 0.817 280 0.00990 1.000 130.4 2485 4.198 1.858 1422 8.29 582 18.6 10.26 0.825 285 0.01387 1.000 99.4 2473 4.189 1.861 1225 8.49 590 18.9 8.81 0.833 290 0.01917 1.001 69.7 2461 4.184 1.864 1080 8.69 598 19.3 7.56 0.841 295 0.02617 1.002 51.94 2449 4.181 1.868 959 8.89 606 19.5 6.62 0.849 300 0.03531 1.003 39.13 2438 4.179 1.872 855 9.09 613 19.6 5,83 0.857 305 0.04712 1.005 29.74 2426 4.178 1.877 769 9.29 620 20.1 5.20 0.865 310 0.06221 1.007 22.93 2414 4.178 1.882 695 9.49 628 20.4 4.62 0,873 315 0.08132 1.009 17.82 2402 4.179 1.888 631 9.69 634 20.7 4.16 0.883 320 0.1053 1.011 13.98 2390 4.180 1.895 577 9.89 640 21.0 3.77 0.894 325 0.1351 1.013 11.06 2378 4.182 1.903 528 10.09 645 21.3 3.42 0.901 330 0.1719 1.016 8.82 2366 4.184 1.911 489 10,29 650 21.7 3.15 0.908 335 0.2167 1.018 7.09 2354 4.186 1.920 453 10.49 656 22.0 2.88 0.916 340 0.2713 1.021 5.74 2342 4.188 1.930 420 10.69 660 22.3 2.66 0.925 4
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