{ "metadata": { "name": "", "signature": "sha256:e1f2ab4731e8126f69d8554acbb321ab940bce50cce33579f99b691416bd49a5" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter 14: Heat Transfer" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.1, page no. 279" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "T = 50.0 #F\n", "Q = 3.9 #B/hr-ft^2\n", "\n", "#calculation\n", "#From table 14.1\n", "k = 0.026 #B/hr-ft-F\n", "dx = k*T/Q\n", "\n", "#result\n", "print \"Required thickness = ft\", round(dx, 3), \"lb/in^2\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Required thickness = ft 0.333 lb/in^2\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.2, page no. 281" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "x1 = 1.0 #in\n", "x2 = 4.0 #in\n", "T1 = 85.0 #F\n", "T2 = 30.0 #F\n", "\n", "#calculation\n", "QbyA = 12*(T1-T2)/(x1/0.3 + x2/0.026)\n", "\n", "#result\n", "print \"Rate of heat flow = \", round(QbyA, 1), \"B/r-ft^2-F\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Rate of heat flow = 4.2 B/r-ft^2-F\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.3, page no. 283" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math\n", "\n", "#initialization\n", "L = 6.5 #in\n", "thick = 1.0 #in\n", "k = 0.06 #B/hr-ft-F\n", "T1 = 350.0 #F\n", "T2 = 110.0 #F\n", "\n", "#calculation\n", "QbyL = 2*math.pi*k*(T1-T2)/math.log(1+2/L)\n", "\n", "#result\n", "print \"heat flow = %d B/hr-ft\" %QbyL" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "heat flow = 337 B/hr-ft\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.4, page no. 283" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math\n", "\n", "#initialization\n", "t = 0.25 #in\n", "dia = 5.5 #in\n", "t2 = 0.6 #in\n", "To = 100.0 #F\n", "kp = 34.5 #B/hr-ft-F\n", "ki = 0.05 #B/hr-ft-F\n", "l = 10.0 #ft\n", "Q = 2000.0 #B/hr\n", "\n", "#calculation\n", "dT = Q*(1/kp *math.log(1+ 2*t/dia) + 1/ki *math.log(1 + 4*t/(dia+2*t)))/(2*math.pi*l)\n", "T1 = dT+To\n", "\n", "#result\n", "print \"Inner surface temperature of the pipe = \", round(T1, 1), \"F\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Inner surface temperature of the pipe = 198.2 F\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.5, page no. 286" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "Tsurr = 90.0 #F\n", "T = 85.0 #F\n", "\n", "#calculation\n", "H = 4.2/(Tsurr-T)\n", "\n", "#result\n", "print \"Film coefficient = %.2f B/hr-ft^2-F\" %H" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Film coefficient = 0.84 B/hr-ft^2-F\n" ] } ], "prompt_number": 7 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.6, page no. 288" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "k = 0.04 #B/hr-ft-F\n", "thick = 1.0 #in\n", "T1 = 90.0 #F\n", "T2 = 30.0 #F\n", "Air = 2.5 #B/hr-ft^2-F\n", "film = 2.0 #B/hr-ft^2-F\n", "\n", "#calculation\n", "U = 1.0/(1.0/Air + thick/12.0/k + 1/film)\n", "Q = U*(T1-T2)\n", "\n", "#result\n", "print \"Rate of heat transfer per unit square area = %.1f B/hr-ft^2\" %Q" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Rate of heat transfer per unit square area = 20.1 B/hr-ft^2\n" ] } ], "prompt_number": 8 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.7, page no. 291" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "import math\n", "\n", "#initialization\n", "U = 115.0 #B/hr-ft^2-F\n", "T1 = 190.0 #F\n", "T2 = 160.0 #F\n", "Tc1 = 65.0 #F\n", "Tc2 = 100.0 #F\n", "w = 140.0 #lbm/min\n", "c = 0.8 #B/lbm F\n", "\n", "#calculation\n", "Q = w*60.0*c*(T1-T2) #answer in textbook for Q is wrong. Hence, the difference in final answer\n", "dT = ((T1-Tc2) - (T2-Tc1))/math.log((T1-Tc2)/(T2-Tc1))\n", "A = Q/(U*dT)\n", "\n", "#result\n", "print \"Required Area = %.1f ft^2\" %A" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Required Area = 19.0 ft^2\n" ] } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.8, page no. 294" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "e = 0.8\n", "T1 = 100+460.0 #R\n", "T2 = 300+460.0 #R\n", "\n", "#calculation\n", "Qdot = 0.173*10**-8 *(T2**4 - T1**4)/(1/e +1/e -1)\n", "\n", "#result\n", "print \"Radiant heat transfer per sq. foot = %d B/hr-ft^2\" %(Qdot+1)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Radiant heat transfer per sq. foot = 272 B/hr-ft^2\n" ] } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Example 14.9, page no. 294" ] }, { "cell_type": "code", "collapsed": false, "input": [ "\n", "#initialization\n", "T1 = 400+460.0 #R\n", "A = 40.0 #in^2\n", "e = 0.1\n", "T2 = 70+460.0 #R\n", "\n", "#calculation\n", "Q = A*e*0.173*10**-8 *(T1**4 - T2**4)/144.0\n", "\n", "#result\n", "print \"Rate of heat transfer = %.2f B/hr\" %Q\n", "#answer in the book is wrong" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Rate of heat transfer = 22.49 B/hr\n" ] } ], "prompt_number": 19 } ], "metadata": {} } ] }