{ "metadata": { "name": "" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "

# Chapter 6: THE SECOND LAW OF THERMODYNAMICS

" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 6.01, page: 133

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "W = 410 #kJ\n", "Qin = 1000 #kJ\n", "Th = 500 #K\n", "Tc = 300 #K\n", "\n", "#calculations:\n", "#cycle thermal efficiency\n", "n = W/Qin\n", "#maximum thermal efficiency\n", "nmax = 1 - Tc/Th\n", "\n", "#Results\n", "print \"cycle thermal efficiency is\", n*100,\"% and maximum thermal efficiency is\",nmax*100,\"%\"\n", "if (n >nmax):\n", " print \"Since the thermal efficiency of the actual cycle exceeds the maximum theoretical value, the claim cannot be valid\"\n", "else:\n", " print \"Since the thermal efficiency of the actual cycle is less than the maximum theoretical value, the claim is valid\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "cycle thermal efficiency is 41.0 % and maximum thermal efficiency is 40.0 %\n", "Since the thermal efficiency of the actual cycle exceeds the maximum theoretical value, the claim cannot be valid\n" ] } ], "prompt_number": 1 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 6.02, page: 134

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "Qcdot = 8000 #kJ/h\n", "Tc = -5 #degC\n", "Th = 22 #degC\n", "Wdotcycle = 3200 #kJ/h\n", "\n", "#calculations:\n", "#coefficient of performance of the refrigerator\n", "beta = Qcdot/Wdotcycle\n", "#coefficient of performance of a reversible refrigeration cycle\n", "betamax = (Tc+273)/(Th-Tc)\n", "\n", "#Results\n", "print \"coefficient of performance of the refrigerator is\", beta\n", "print \"coefficient of performance of a reversible refrigeration cycle\", round(betamax,1)\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "coefficient of performance of the refrigerator is 2.5\n", "coefficient of performance of a reversible refrigeration cycle 9.9\n" ] } ], "prompt_number": 2 }, { "cell_type": "markdown", "metadata": {}, "source": [ "

## Example 6.03, page: 135

" ] }, { "cell_type": "code", "collapsed": false, "input": [ "from __future__ import division\n", "import math\n", "\n", "# Initialization of Variable\n", "Qh = 6E5 #Btu/day\n", "Th = 70 #degF\n", "Tc = 32 #degF\n", "cost = 8 #cents/kW\n", "\n", "#calculations:\n", "#temps in Rankine\n", "Thr = ((Th - 32)*5/9 +273)*1.8\n", "Tcr = ((Tc - 32)*5/9 +273)*1.8\n", "#Work\n", "Wcycle = (1 - Tcr/Thr)*Qh\n", "#costperday\n", "cpd = (Wcycle/3413)*cost/100 #\$/day\n", "\n", "#Results\n", "print \"minimum theoretical work input is\", round(Wcycle,1),\"Btu/day\"\n", "print \"minimum theoretical cost per day is\", round(cpd,2),\"\$/day\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "minimum theoretical work input is 43067.6 Btu/day\n", "minimum theoretical cost per day is 1.01 \$/day\n" ] } ], "prompt_number": 3 } ], "metadata": {} } ] }