{ "metadata": { "name": "", "signature": "sha256:645f0312235dca513f2dc1a6a9e79defd41db0b001d5f5d700ed6a60e922990d" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Ch -1 : Thermodynamic Cycles for Gas Engines" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.1 : Pg - 21" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#initialisation of variables\n", "t2=275 #k\n", "t1=1100 #k\n", "R = 0.287 # kJ/kgK\n", "y = 1.4\n", "qs = 250 # kJ/kgK\n", "pa = 1.01325 # bar\n", "th=393 #k\n", "re=0.14\n", "#CALCULATIONS\n", "eff = 1-t2/t1\n", "from sympy import symbols, solve, log\n", "p1,pb = symbols('p1 pb')\n", "expr = t1/t2-(p1/pa)**((y-1)/y)\n", "p1 = float(solve(expr,p1)[0])\n", "expr2 = qs-R*t1*log(pb/p1)\n", "pb = float(solve(expr2,pb)[0])\n", "va = R*t2/pa\n", "vb = R*t1/pb\n", "mep = qs*eff/(va-vb)\n", "#RESULTS\n", "print \"Cycle efficiency = %0.2f \\nmean effective pressure = %0.3f bar\"%(eff, mep)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Cycle efficiency = 1.00 \n", "mean effective pressure = 3.256 bar\n" ] } ], "prompt_number": 1 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.2 : Pg - 22" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#initailisation variables\n", "d=20 #cm\n", "l=25 #cm\n", "cv=1400 #cc\n", "g=1.4\n", "#CALCULATIONS\n", "sv=(22/7*d**2*l)/4\n", "tv=sv+cv\n", "r=tv/cv\n", "e=1-1/(r)**(g-1)\n", "print 'otto efficiency is %.3f'%e" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "otto efficiency is 0.512\n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.3 : Pg - 22" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#initialisation of variables\n", "t1=305 #K\n", "t3=1920 #K\n", "r=7\n", "g=1.4\n", "p1=1 #bar\n", "cv=0.718\n", "R=0.287 #kj/kgk\n", "#CALCULATIONS\n", "print \"part(a): \"\n", "t2=t1*r**(g-1)\n", "p2=p1*r**(g)\n", "print \"T2 = %0.f K\"%t2\n", "print \"P2 = %0.1f bar\"%p2\n", "p3=p2*(t3/t2)\n", "print \"T3 = %0.f K\"%t3\n", "print \"P3 = %0.1f bar\"%p3\n", "t4=t3*1/r**(g-1)\n", "p4=p3*(1/r)**(g)\n", "print \"T4 = %0.f K\"%t4\n", "print \"P4 = %0.2f bar\"%p4\n", "print \"part(b) :\"\n", "qs=cv*(t3-t2)\n", "print \"Heat Supplied, qs = %0.1f kJ/kg/cycle\"%qs\n", "qr1=cv*(t4-t1)\n", "print \"part(c) :\"\n", "print \"Heat rejected, qr = %0.1f kJ/kg/cycle\"%qr1\n", "wo=qs-qr1\n", "print \"part(d) : \"\n", "print \"Work Output = %0.1f kJ/kg/cycle\"%wo\n", "print \"part(e) : \"\n", "ef=wo/qs\n", "print \"Efficiency = %0.3f\"%ef\n", "v1=R*t1/p1\n", "v2=v1/r\n", "sv=v1-v2\n", "cl=v2/(v1-v2)\n", "print \"part(f) : \\nclearance = %0.4f\"%cl\n", "mep=wo/sv\n", "print 'part(g) : \\nmean effective pressure is %0.3f bar'%mep" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "part(a): \n", "T2 = 664 K\n", "P2 = 15.2 bar\n", "T3 = 1920 K\n", "P3 = 44.1 bar\n", "T4 = 882 K\n", "P4 = 0.00 bar\n", "part(b) :\n", "Heat Supplied, qs = 901.6 kJ/kg/cycle\n", "part(c) :\n", "Heat rejected, qr = 414.0 kJ/kg/cycle\n", "part(d) : \n", "Work Output = 487.6 kJ/kg/cycle\n", "part(e) : \n", "Efficiency = 0.541\n", "part(f) : \n", "clearance = 0.1667\n", "part(g) : \n", "mean effective pressure is 6.499 bar\n" ] } ], "prompt_number": 3 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.4 : Pg - 23" ] }, { "cell_type": "code", "collapsed": false, "input": [ " \n", "#initialisation of variables\n", "r=14\n", "g=1.4\n", "x=1.78 #x=v3/v2\n", "#CALCULATIONS\n", "oef=1-(1/14)**(g-1)\n", "Def=1-((1/(14)**(g)*1.4))*((x**(g) -1)/(x-1))\n", "print 'otto efficiency is %0.3f'%oef" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "otto efficiency is 1.000\n" ] } ], "prompt_number": 4 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.5 : Pg - 24" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#1.5\n", "from __future__ import division\n", "#initialisation of variables\n", "t1=300 #K\n", "t3=1900 #K\n", "r=15\n", "g=1.4\n", "p1=1 #bar \n", "cp=1.005\n", "cv=0.718\n", "R=0.287 #kj/kgk\n", "#CALCULATIONS\n", "t2=t1*r**(g-1)\n", "p2=p1*r**(g)\n", "p3=p2\n", "t4=t3*0.143**(g-1)\n", "p4=p3*(0.143)**(g)\n", "qs=cp*(t3-t2)\n", "qr1=cv*(t4-t1)\n", "wo=qs-qr1\n", "ef=wo/qs\n", "v1=R*t1/p1/1e2\n", "v2=v1/r\n", "sv=v1-v2\n", "cl=v2/(v1-v2)\n", "v3 = t3/t2*v2\n", "cf = (v3-v2)/(v1-v2)\n", "mep=wo/sv\n", "print \"part(a) : \\nT2 = %0.f K\\nP2 = %0.1f bar\\nT4 = %0.f K\\nP4 = %0.2f bar\"%(t2,p2,t4,p4)\n", "print \"part(b) : \\nHeat Supplied, qs = %0.2f\"%qs\n", "print \"part(c) : \\nHeat rejected, qr = %0.2f kJ/kg/cycle\"%qr1\n", "print \"part(d) : \\nNet work output = %0.2f kJ/kg/cycle\" %wo\n", "print \"part(e) : \\nEfficiency = %0.4f \"%ef\n", "print \"part(f) : \\nClearance = %0.5f\"%cl\n", "print \"part(g) : \\nCut-off = %0.4f\"%cf\n", "print 'part(h) : \\nmean effective pressure is %0.f kN/m^2'%mep" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "part(a) : \n", "T2 = 886 K\n", "P2 = 44.3 bar\n", "T4 = 873 K\n", "P4 = 2.91 bar\n", "part(b) : \n", "Heat Supplied, qs = 1018.82\n", "part(c) : \n", "Heat rejected, qr = 411.23 kJ/kg/cycle\n", "part(d) : \n", "Net work output = 607.58 kJ/kg/cycle\n", "part(e) : \n", "Efficiency = 0.5964 \n", "part(f) : \n", "Clearance = 0.07143\n", "part(g) : \n", "Cut-off = 0.0817\n", "part(h) : \n", "mean effective pressure is 756 kN/m^2\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.6 : Pg - 25" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#initialisation of variables \n", "t1=300 #temparature in k\n", "r=10 #compression ratio\n", "p1=1 #pressure in bar\n", "g=1.4 \n", "p3=40 #pressure in bar\n", "x=0.166 #x=v4/v5=t4/v1=(v4/v2)*(v2/v1)\n", "t4=2000 #temparature in k\n", "p4=40 #pressure in bar\n", "cv=0.718 #calorific value(const volume)\n", "cp=1.005 #calorific value(const preussure)\n", "R=0.287\n", "r=10\n", "#CALCULATIONS\n", "t2=(t1*(r)**(g-1))\n", "p2=(p1*(r)**(g))\n", "t3=t2*(p3/p2)\n", "t5=t4*(x)**(g-1)\n", "p5=p4*(x)**(g)\n", "q23=cv*(t3-t2)\n", "q34=cp*(t4-t3)\n", "q44=cv*(t5-t1)\n", "nwd=q23+q34-q44\n", "ef=nwd/(q23+q34)\n", "v1=(R*t1)/(p1*100)\n", "v2=v1/r\n", "mep=nwd/(v1-v2)\n", "effo=1-(1/(r)**(g-1))\n", "v3=(R*t4)/(p2*100)\n", "cr=v3/v2\n", "effd=1-((1/(r)**(g-1))*(1/g)*((cr)**(g)-1)/(cr-1))\n", "#RESULTS\n", "print '(a) temparature 2,3,5 and pressure 2,5 are %.fk,%.fk,%.fk and %0.f bar,%0.2f bar'%(t2,t3,t5,p2,p5)\n", "print '\\n(b) heat supplied at const volume is %.2f kJ/kg/cycle'%q23\n", "print '\\n(c) heat supplied at const pressure is %.2f kJ/kg/cycle'%q34\n", "print '\\n(d) heat rejected is %.2f kJ/kg/cycle'%q44\n", "print '\\n(e) net work output is %.2f'%nwd\n", "print '\\n(f) efficiency is %.4f'%ef\n", "print '\\n(g) otto efficiency is %0.3f'%effo,\n", "print ' & diesel efficiency is %0.3f'%effd" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "(a) temparature 2,3,5 and pressure 2,5 are 754k,1200k,975k and 25 bar,3.24 bar\n", "\n", "(b) heat supplied at const volume is 320.54 kJ/kg/cycle\n", "\n", "(c) heat supplied at const pressure is 804.00 kJ/kg/cycle\n", "\n", "(d) heat rejected is 484.76 kJ/kg/cycle\n", "\n", "(e) net work output is 639.78\n", "\n", "(f) efficiency is 0.5689\n", "\n", "(g) otto efficiency is 0.602 & diesel efficiency is 0.498\n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex - 1.7 : Pg - 27" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#initialisation of variables\n", "t1=295 #temparature in k\n", "r=5.25\n", "g=1.4\n", "t3=923 #temparature in k\n", "tc=511 #temparature in k\n", "tt=633 #temparature in k\n", "#CALCULATIONS\n", "t2=t1*(r)**((g-1)/g)\n", "t4=t3/(r)**((g-1)/g)\n", "effb=1-((t4-t1)/(t3-t2))\n", "wt=t3-t4\n", "wc=t2-t1\n", "wr1=(1-(t2-t1)/(t3-t4))\n", "ctwr1=(t2-t1)/(t3-t4)\n", "effc=(t2-t1)/(tc-t1)\n", "efft=(t3-tt)/(t3-t4)\n", "effbr=1-((tt-t1)/(t3-tc))\n", "wr2=1-((tc-t1)/(t3-tt))\n", "ctwr2=(tc-t1)/(t3-tt)\n", "#RESULTS\n", "print 'work ratio and compressed turbine wrok ratio in first part of problem are %.3f and %0.3f'%(wr1,ctwr1)\n", "print '\\nwork ratio and compressed turbine wrok ratio in second part of problem are %0.3f and %0.3f'%(wr2,ctwr2)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "work ratio and compressed turbine wrok ratio in first part of problem are 0.487 and 0.513\n", "\n", "work ratio and compressed turbine wrok ratio in second part of problem are 0.255 and 0.745\n" ] } ], "prompt_number": 7 } ], "metadata": {} } ] }