{ "metadata": { "name": "", "signature": "sha256:13df1b90ea06630bb54a561fa81d4ebbaaa2d68a225d0631603576a208acfb40" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "CHAPTER13:Gas Mixtures" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.3:Pg-533" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques3\n", "#calculating humidity ratio, dew point,mass of air, mass of vapor\n", "\n", "r=0.70;#relative humidity\n", "Pg=5.628;#saturation pressure in kPa\n", "Pv=r*Pg;#vapour pressure in kPa\n", "P=100;#net pressure kPa \n", "Pa=P-Pv;#Partial pressure of air\n", "w=0.622*Pv/Pa;#humidity ratio formula\n", "V=100;#volume in m^3\n", "Ra=0.287;#gas constant for water vapour\n", "T=308.2;#Temperature in K\n", "ma=Pa*V/(Ra*T);#mass in kg\n", "mv=w*ma;#mass of vapour\n", "print\" Mass of vapour is\",round(mv,3),\"Kg \"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ " Mass of vapour is 2.77 Kg \n" ] } ], "prompt_number": 2 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.3E:Pg-533" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques3\n", "#calculating humidity ratio, dew point,mass of air, mass of vapor\n", "\n", "r=0.70;#relative humidity\n", "Pg=0.6988 ;#saturation pressure in lbf/in^2\n", "Pv=r*Pg;#vapour pressure in lbf/in^2\n", "P=14.7;#net pressure in lbf/in^2\n", "Pa=P-Pv;#Partial pressure of air\n", "w=0.622*Pv/Pa;#humidity ratio formula\n", "V=2000;#volume in ft^3\n", "Ra=53.34;#gas constant for water vapour\n", "T=70;#Temperature in F\n", "ma=Pa*V*144/(Ra*(T+480));#mass in lbm\n", "mv=w*ma;#mass of vapour\n", "print\" Mass of vapour is\",round(mv,2),\"lbm\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ " Mass of vapour is 2.99 lbm\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.4:Pg-534" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques4 \n", "#calculating amount of water vapour condensed on cooling\n", "\n", "#from example 3\n", "w1=0.0255;#w1=w, humidity ratio at initial temperature\n", "ma=108.6;#mass of air in kg\n", "P=100;#kPa net pressure\n", "#at 5 C mixture is saturated so Pv2=Pg2\n", "Pg2=0.8721;\n", "Pv2=Pg2;\n", "w2=0.622*Pv2/(P-Pg2);\n", "mc=ma*(w1-w2);\n", "print\"Mass of vapour condense is \",round(mc,3),\"kg \"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Mass of vapour condense is 2.175 kg \n" ] } ], "prompt_number": 6 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.4E:Pg-535" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques4 \n", "#calculating amount of water vapour condensed on cooling\n", "\n", "#from example 3 \n", "w1=0.02135;#w1=w, humidity ratio at initial temperature\n", "ma=139.6;#mass of air in lbm\n", "P=14.7;#net pressure in lbf/in^2\n", "#at 40 degree F mixture is saturated so Pv2=Pg2\n", "Pg2=0.1217 # lbf/in^2\n", "Pv2=Pg2;\n", "w2=0.622*Pv2/(P-Pg2);# humidity ratio at final temperature\n", "mc=ma*(w1-w2); #Mass of vapour condense in lbm\n", "print\"Mass of vapour condense is \",round(mc,3),\"lbm \"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Mass of vapour condense is 2.256 lbm \n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.5:Pg-536" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques5\n", "#calculating heat transfer per kilogram of dry air\n", "\n", "#1-inlet state\n", "#2-Exit state\n", "r1=0.80;#realtive humidity at state 1\n", "Pg1=4.246;#saturation pressure of vapour in kPa\n", "P1=105.0;#net pressure at state 1 in kPa\n", "P2=100.0;#net pressure at state 2 in kPa\n", "Pv1=r1*Pg1;#partial pressure of vapour in kPa\n", "w1=0.622*Pv1/(P1-Pv1);#humidity ratio at state 1\n", "r2=0.95;#relative humidity at state 2\n", "Pg2=1.7051;#saturation pressure of vapour in kPa\n", "Pv2=r2*Pg2;#partial pressure of vapour in kPa\n", "w2=0.622*Pv2/(P2-Pv2);#humidity ratio at state 2\n", "T1=30.0;#C\n", "T2=15.0;#C\n", "Cp=1.004;#specific heat of water vapour in kJ/kg\n", "hv2=2528.9;#enthalpy of vapourisation of vapour in kJ/kg\n", "hv1=2556.3;#enthalpy of vapourisation of vapour in kJ/kg\n", "hl2=62.99;#enthalpy of \n", "q=Cp*(T2-T1)+w2*hv2-w1*hv1+hl2*(w1-w2);#kJ/kg\n", "print\" Heat transferred per unit mass =\",round(q,1),\"kJ/kg of dry air\"" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ " Heat transferred per unit mass = -41.7 kJ/kg of dry air\n" ] } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.6:Pg-537" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques6\n", "#calculating heat transferred in gas vapour mixture\n", "\n", "#n-Nitrogen\n", "#v-water vapour\n", "Pn2=1995;#Pressure of nitrogen in kPa\n", "V=0.5;#Volume in m^3\n", "Rn2=0.2968;#Gas constant for nitrogen in kJ/kg.K\n", "Rv=0.4615;#gas constant for vapour\n", "T1=323.2;#Temperature in K\n", "T2=283.2;#Temperature in K\n", "Pv1=5;#Pressure of water vapour in kPa at state 1\n", "Pv2=1.2276;#Pressure of water vapour in kPa at state 2\n", "mn2=Pn2*V/(Rn2*T1);#mass of nitrogen\n", "mv1=Pv1*V/(Rv*T1);#mass of vapour in kg\n", "mv2=Pv2*V/(Rv*T2);#mass of vapour in kg\n", "ml2=mv1-mv2;#mass of liquid condensed n kg\n", "uv1=2443.1;#specific internal energy of vapour in kJ/kg at state 1\n", "uv2=2389.2;#specific internal energy of vapour in kJ/kg at state 2\n", "ul2=42.0;#specific internal energy of liquid water in kJ/kg\n", "Cv=0.745;#specific heat at constant volume in kJ/kg.K\n", "Q=mn2*Cv*(T2-T1)+mv2*uv2+ml2*ul2-mv1*uv1;\n", "print\"Heat transferred =\",round(Q,2),\"kJ \"\n", "\n", "#the answer is different in book due to intermediate approximization " ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "Heat transferred = -339.1 kJ \n" ] } ], "prompt_number": 13 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.7:Pg-539" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques7\n", "#calculating humidity ratio and relative humidity \n", "\n", "#1-Inlet state\n", "#2-Exit state\n", "P=100;#net pressure in kPa \n", "#it is steady state adiabatic process\n", "#water vapour leaving is saturated so Pv2=Pg2\n", "Pg2=2.339;#saturation pressure of vapour in kPa\n", "Pv2=Pg2;#partial pressure of vapour\n", "w2=0.622*Pv2/(P-Pg2);\n", "Cpa=1.004;#specific heat n kJ/kg/K\n", "T2=20;# final temp in C\n", "T1=30;# initial temp in C\n", "Hfg2=2454.1;#specific heat difference at state 2 in kJ/kg\n", "hv1=2556.3;#enthalpy of water vapour at state 1 in kJ/kg\n", "hl2=83.96;#enthalpy of liquid water in kJ/kg\n", "w1=(Cpa*(T2-T1)+w2*Hfg2)/(hv1-hl2);\n", "print \" Relative humidity =\",round(w1,4)\n", "#also w1=0.622*Pv1/(100-Pv2)\n", "Pv1=100*w1/(0.622+w1);\n", "Pg1=4.246;#saturation pressure at state 1 in kPa\n", "r=Pv1/Pg1;#humidity ratio\n", "print\" Humidity ratio =\",round(r,4)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ " Relative humidity = 0.0107\n", " Humidity ratio = 0.3993\n" ] } ], "prompt_number": 16 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex13.7E:Pg-540" ] }, { "cell_type": "code", "collapsed": false, "input": [ "#ques7\n", "#calculating humidity ratio and relative humidity \n", "\n", "#1-Inlet state\n", "#2-Exit state\n", "P=14.7;#net pressure in lbf/in^2\n", "#it is steady state adiabatic process\n", "#water vapour leaving is saturated so Pv2=Pg2\n", "Pg2=0.3632;#saturation pressure of vapour in lbf/in^2\n", "Pv2=Pg2;#partial pressure of vapour\n", "w2=0.622*Pv2/(P-Pg2);\n", "Cpa=0.24;#specific heat n Btu/lbm/F\n", "T2=70;# final temp in F\n", "T1=84;# initial temp in F\n", "Hfg2=1054.0;#specific heat difference at state 2 in Btu/lbm\n", "hv1=1098.1;#enthalpy of water vapour at state 1 in Btu/lbm\n", "hl2=38.1;#enthalpy of liquid water in Btu/lbm\n", "w1=(Cpa*(T2-T1)+w2*Hfg2)/(hv1-hl2);\n", "print \" Relative humidity =\",round(w1,4)\n", "#also w1=0.622*Pv1/(100-Pv2)\n", "Pv1=14.7*w1/(0.622+w1);\n", "Pg1=0.584;#saturation pressure at state 1 in lbf/in^2\n", "r=Pv1/Pg1;#humidity ratio\n", "print\" Humidity ratio =\",round(r,4)" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ " Relative humidity = 0.0125\n", " Humidity ratio = 0.4958\n" ] } ], "prompt_number": 18 } ], "metadata": {} } ] }