{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 4 : First Law of Thermodynamics" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.1 Page No : 80" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Work done by the pump upon the water in MJ is : 90\n" ] } ], "source": [ "import math \n", "\n", "# Variables\t\t\t\n", "p = 1.0;\t\t\t# in MPa\n", "p = p * 10**6;\t\t\t# in N per m**2\n", "del_v = 1.5;\t\t\t# in m**3 per min\n", "\n", "# Calculations\n", "del_v = del_v * 60;\t\t\t# in m**3 per h\n", "W = p * del_v;\t\t\t# in J\n", "W = W * 10**-6;\t\t\t# in MJ\n", "\n", "# Results\n", "print \"Work done by the pump upon the water in MJ is : %.0f\"%W\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.2 Page No : 81" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Height from which the mass should fall in meter is : 89.63\n" ] } ], "source": [ "\n", "# Variables\n", "# w = 2*g*h\n", "g = 9.81;\n", "m =(0.2+10./1000)*10**3 ;\t\t\t# in gm\n", "s = 1;\t\t\t# in cal/gm°C\n", "del_T = 2;\t\t\t# in °C\n", "\n", "# Calculations\n", "H = m * s * del_T;\t\t\t# in cal\n", "H = H * 10**-3;\t\t\t# kcal\n", "J = 4.1868 * 1000;\n", "# W= 2*g*h= J*H\n", "h = J*H/(2 * g);\t\t\t# in m\n", "\n", "# Results\n", "print \"Height from which the mass should fall in meter is : %.2f\"%h\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.3 Page No : 83" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Third Heat transfer in kJ is -5\n", "That is Third Heat transfer is of 5 kJ from the fluid\n" ] } ], "source": [ "\n", "# Variables\n", "W1 = -25;\t\t\t# in kJ\n", "W2 = 45;\t\t\t# in kJ\n", "Q1 = 65;\t\t\t# in kJ\n", "Q2 = -40;\t\t\t# in kJ\n", "\n", "# Calculations\n", "# del_U = Q - W and but for a cycle del_U = 0, So\n", "# Q = W\n", "# Q1 + Q2 +Q3 = W1 +W2\n", "Q3 = W1 + W2 - Q1 - Q2;\t\t\t# in kJ\n", "\n", "# Results\n", "print \"Third Heat transfer in kJ is \",Q3\n", "print \"That is Third Heat transfer is of \",abs(Q3),\" kJ from the fluid\"\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.5 Page No : 98" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "The external work done in kcal is : 14.2\n" ] } ], "source": [ "\n", "# Variables\t\t\t\n", "m = 1.5;\t\t\t# in kg\n", "T1 = 90;\t\t\t# in °C\n", "T1 = T1 + 273;\t\t\t#in K\n", "T2 = 225;\t\t\t# in °C\n", "T2 = T2 + 273;\t\t\t# in K\n", "C_p = 0.24;\n", "C_v = 0.17;\n", "\n", "# Calculations\n", "Q = (m * C_p * (T2-T1));\t\t\t# in kcal\n", "del_U = (m * C_v * (T2-T1));\t\t\t# in kcal\n", "W = Q - del_U;\t\t\t# in kcal\n", "\n", "# Results\n", "print \"The external work done in kcal is : %.1f\"%W\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.7 Page No : 98" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Mass of gas in mole is : 24.20\n", "Temperature at the end of compression in °C is : 286.5\n", "Value of index n of compression is : 1.3\n", "Increase in internal energy of gas in kJ is : 56.2\n", "Heat interaction in kJ is : -72.24\n", "The -ve sign indicates heat rejection during the process\n" ] } ], "source": [ "import math \n", "\n", "# Variables\n", "v1 = 0.5;\t\t\t# in m**3\n", "v2 = 0.125;\t\t\t# in m**3\n", "p1 = 1.5;\t\t\t# in bar\n", "p1 = p1 * 10**5;\t\t\t# in N per m**2\n", "p2 = 9.;\t\t\t#in bar\n", "p2 = p2 * 10**5;\t\t\t# in N per m**2\n", "T1 = 100.;\t\t\t# in °C\n", "T1 = T1 + 273;\t\t\t# in K\n", "R = 8.31;\n", "\n", "# Calculations and Results\n", "# Formula p1*v1= n*R*T1\n", "n= p1*v1/(R*T1);\t\t\t# in mole\n", "print \"Mass of gas in mole is : %.2f\"%n\n", "\n", "# Part (b)\n", "# Formula p1*v1/T1 = p2*v2/T2\n", "T2 = (p2 * v2 * T1)/(p1 * v1);\t\t\t# in K\n", "print \"Temperature at the end of compression in °C is : %.1f\"%(T2-273)\n", "\n", "# Part (c)\n", "# Formula p1*v1**n = p2*v2**n\n", "n1= math.log(p2/p1)/math.log(v1/v2)\n", "print \"Value of index n of compression is :\",round(n1,1)\n", "\n", "# Part (d)\n", "F = 3;\n", "C_v =1./2*R*F;\n", "del_U = (n * C_v * (T2-T1));\t\t\t# in J\n", "print \"Increase in internal energy of gas in kJ is : %.1f\"%(del_U*10**-3)\n", "\n", "# Part(e)\n", "Gamma = 1.67;\n", "Q_12 = n*(Gamma-n1)/(1-n1)*R*(T2-T1)/(Gamma-1);\t\t\t# in J\n", "Q_12 = Q_12 * 10**-3;\t\t\t # in kJ\n", "print \"Heat interaction in kJ is : %.2f\"%Q_12\n", "\n", "if Q_12<0:\n", " print \"The -ve sign indicates heat rejection during the process\"\n", "\n", "# Note: There is some difference between the answer of book and coding . Both the answer is right but accurate answer is of coding.\n", "# Because in the book, the intermediate values taken are appox. and in the coding the values taken are accurate\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.8 Page No : 99" ] }, { "cell_type": "code", "execution_count": 10, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Part (a) The value of n is : 1.34\n", "The process followed during air compression is POLYTROPIC\n", "Part (b) The law of the process is 1.34 p*v** = constant\n", "Part (c) Work done during the process in kJ is : -73.5\n", "The -ve sign indicates that the work has been done on the system\n", "Part (d) Heat transfer during the process in kJ is : -11.029\n", "The -ve sign indicates that the heat is rejected from the system\n" ] } ], "source": [ "import math \n", "\n", "# Variables\n", "p1 = 0.01;\t\t\t# in N/mm**2\n", "p1 = p1 * 10**3;\t\t\t# in kN/m**2\n", "p2 = 50.;\t\t\t# in kN/m**2\n", "v1 = 5.;\t\t\t# in m**3\n", "v2 = 1.5;\t\t\t# in m**3\n", "Gamma = 1.4;\n", "\n", "# Calculations and Results\n", "# Formula p1*v1**n = p2*v2**n\n", "n= round(math.log(p2/p1)/math.log(v1/v2),2)\n", "print \"Part (a) The value of n is : %.2f\"%n\n", "print (\"The process followed during air compression is POLYTROPIC\");\n", "\n", "# Part (b)\n", "print \"Part (b) The law of the process is %.2f p*v**\"%n,\" = constant\"\n", "\n", "# Part (c)\n", "W= (p1*v1-p2*v2)/(n-1);\t\t\t# in kNm or (kJ)\n", "print \"Part (c) Work done during the process in kJ is : %.1f\"%W\n", "print (\"The -ve sign indicates that the work has been done on the system\")\n", "\n", "# Part (d)\n", "Q = ((Gamma - n)/(Gamma - 1) * W);\t\t\t# in kJ\n", "print \"Part (d) Heat transfer during the process in kJ is : %.3f\"%Q\n", "print (\"The -ve sign indicates that the heat is rejected from the system\")\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.9 Page No : 101" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Change in internal energy in kJ is 60.0\n", "The value of a in kN/m**2 is 1160.0\n", "The value of b in kN/m**2 is -800.0\n", "Work done in kJ is : 600.0\n", "The net heat transfer in kJ is : 660.0\n" ] } ], "source": [ "from scipy.integrate import quad \n", "\n", "\n", "# Variables\n", "# Relation of specific internal energy of the gas\n", "# U= 1.5*p*v-85 kJ/kg\n", "p1 = 1000;\t\t\t# in kpa\n", "p2 = 200;\t\t\t# in pa\n", "v1 = 0.20;\t\t\t# in m**3\n", "v2 = 1.20;\t\t\t# in m**3\n", "m = 1.5;\t\t\t# in kg\n", "\n", "# Calculations and Results\n", "U1= 1.5*p1*v1-85;\t\t\t# kJ/kg\n", "U2= 1.5*p2*v2-85;\t\t\t# kJ/kg\n", "delU= U2-U1;\t \t\t# in kJ\n", "print \"Change in internal energy in kJ is\",delU\n", "# p1= a+b*v1 (i)\n", "# p2= a+b*v2 (ii)\n", "# From eq(i) and (ii)\n", "b= (p1-p2)/(v1-v2);\t\t\t# in kN/m**2\n", "a= p1-b*v1; \t\t\t# in kN/m**2 \n", "print \"The value of a in kN/m**2 is \",a\n", "print \"The value of b in kN/m**2 is \",b\n", "\n", "# Part (c)\n", "# Work done = integration of p w.r.t. v and p = a+b*v1\n", "\n", "def f5(v): \n", " return a+b*v\n", "\n", "W= quad(f5,v1,v2)[0]\n", "print \"Work done in kJ is :\",W\n", "\n", "# Part (d)\n", "Q= delU+W;\t\t\t# in kJ\n", "print \"The net heat transfer in kJ is : \",Q\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.10 Page No : 102" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "The maximum internal energy of the gas in kJ/kg is : 818.625\n" ] } ], "source": [ "\n", "# Variables\n", "a= 1160.;\t\t\t# in kN/m**2\n", "b= -800.;\t\t\t# in kN/m**2\n", "\n", "# Calculations\n", "v= -a/(2*b)\n", "Umax= 1.5*(a*v+b*v**2)-85;\t\t\t# in kJ/kg\n", "# For 1.5 kg mass of gas it is\n", "Umax= Umax*1.5;\t\t\t# in kJ/kg\n", "\n", "# Results\n", "print \"The maximum internal energy of the gas in kJ/kg is : \",Umax\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.11 Page No : 103" ] }, { "cell_type": "code", "execution_count": 8, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "The exit velocity of air in m/s is : 594.094\n", "Inlet area of the nozzle in square milimeter is : 31.89\n", "Exit area of nozzel in square milimeter is : 43.35\n" ] } ], "source": [ "# Exa 4.11\n", "import math \n", "\n", "# Variables\n", "T1 = 127.;\t\t\t# in °C\n", "T1 = T1 + 273;\t\t\t# in K\n", "R = 287.;\n", "V1 = 300.;\t\t\t# in m/s\n", "p1 = 2.;\t\t\t# in MPa\n", "p2 = 0.5;\t\t\t# in MPa\n", "p1 = p1 * 10**6;\t\t\t# in Pa\n", "p2 = p2 * 10**6;\t\t\t# in Pa\n", "C_P = 1.005*10**3;\t\t\t# in J/ kg-K\n", "Gamma = 1.4;\n", "\n", "# Calculations and Results\n", "V2 = math.sqrt(2 * C_P *T1 *(1-(p2/p1)**((Gamma-1)/Gamma)) + V1**2);\t\t\t# in m/s\n", "print \"The exit velocity of air in m/s is : %.3f\"%V2\n", "\n", "m = 600.;\t\t\t# in kg/hr\n", "m = m / 3600;\t\t\t# in kg/sec\n", "v1 = (R * T1)/p1;\t\t\t# in m**3 per kg\n", "# m = (A1*V1)/v1 = (A2* V2)/v2\n", "A1 = (m * v1)/V1;\t\t\t# in m**2\n", "A1 = A1 * 10**6;\t\t\t# in mm**2\n", "print \"Inlet area of the nozzle in square milimeter is : %.2f\"%A1\n", "\n", "T2 = T1*(p2/p1)**((Gamma-1)/Gamma);\t\t\t# in K\n", "v2 = (R * T2)/(p2);\t\t\t# in m**3/kg\n", "A2 = (m * v2)/V2;\t\t\t# in m**2\n", "A2 = A2 * 10**6;\t\t\t# in mm**2\n", "print \"Exit area of nozzel in square milimeter is : %.2f\"%A2\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.17 Page No : 106" ] }, { "cell_type": "code", "execution_count": 13, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Net heat transfer for the system in MJ is : -8.6\n" ] } ], "source": [ "\n", "# Variables\n", "W = -1;\t\t\t# in kWh\n", "W = W * 10**3 * 3600;\t\t\t# in J\n", "del_U = -5000;\t\t\t# in kj\n", "\n", "# Calculations\n", "del_U = del_U * 10**3;\t\t\t# in J\n", "Q = del_U + W;\t\t\t# in J\n", "Q = Q * 10**-6;\t\t\t# in MJ\n", "\n", "# Results\n", "print \"Net heat transfer for the system in MJ is : \",Q\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.20 Page No : 107" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Heat flows into the system along the path a b d in kJ is : 62.5\n", "Heat liberated by the system in kJ is : -73\n", "Heat absorbed in processes ad in kJ is : 52.5\n", "Heat absorbed in processes bd in kJ is : 10\n", "Heat absorbed in processes in ad and db in kJ is : 10.5\n" ] } ], "source": [ "\n", "# Variables\n", "Q_acb = 84;\t\t\t#in kJ\n", "W_acb = 32;\t\t\t# in kJ\n", "\n", "# Calculations and Results\n", "#Formula Q_acb = del_U+W_acb where del_U = U_b - U_a;\n", "del_U = Q_acb - W_acb;\t\t\t# in kJ\n", "# Part (a) Path a b d\n", "W_abd = 10.5;\t\t\t# in kJ\n", "Q_abd = del_U + W_abd;\t\t\t# in kJ\n", "print \"Heat flows into the system along the path a b d in kJ is : \",Q_abd\n", "\n", "# Part (b) curved path b a\n", "W_ba = -(21);\t\t\t# in kJ\n", "Q_ba = -(del_U) + W_ba;\t\t\t# in kJ\n", "print \"Heat liberated by the system in kJ is : \",(Q_ba)\n", "\n", "# Part (c) process a b and d b\n", "W_ad = 10.5;\t\t\t# in kJ\n", "del_U1 = 42;\t\t\t# in kJ\n", "Q_ad = del_U1 + W_ad;\t\t\t# in kJ\n", "print \"Heat absorbed in processes ad in kJ is : \",Q_ad\n", "\n", "W_db = -(42);\t\t\t# in kJ\n", "del_U2 = 52;\t\t\t# in kJ\n", "Q_bd = del_U2 + W_db;\t\t\t# in kJ\n", "print \"Heat absorbed in processes bd in kJ is : \",Q_bd\n", "\n", "W_db = 0;\n", "W_abd = W_ad + W_db;\t\t\t# in kJ\n", "print \"Heat absorbed in processes in ad and db in kJ is : \",W_abd\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 4.21 Page No : 108" ] }, { "cell_type": "code", "execution_count": 11, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "net work done in kJ is : -94.02\n" ] } ], "source": [ "\n", "# Variables\n", "v1 = 5.;\t\t\t# in m**3\n", "p1 = 2.;\t\t\t# in bar\n", "p2 = 6.;\t\t\t# in bar\n", "p3 = 2.;\t\t\t# in bar\n", "\n", "# Calculations\n", "p1 = p1 * 10**5;\t\t\t# in N/m**2\n", "p2 = p2 * 10**5;\t\t\t# in N/m**2\n", "p3 = p3 * 10**5;\t\t\t# in N/m**2\n", "n = 1.3;\n", "v2 = v1 * ((p1/p2)**(1/1.3));\t\t\t# in m**3\n", "W1_2 = ((p2 * v2)-(p1 * v1))/(1-n);\t\t\t# in J\n", "Gamma = 1.4;\n", "v3 = v2 * ((p2/p3)**(1/Gamma));\t\t\t# in m**3\n", "W2_3 = ((p3 * v3) - (p2 * v2))/(1-Gamma);\t\t\t# in J\n", "W_net = W1_2 + W2_3;\t\t\t# in J\n", "W_net = W_net * 10**-3;\t\t\t# in kJ\n", "\n", "# Results\n", "print \"net work done in kJ is : %.2f\"%W_net\n" ] } ], "metadata": { "kernelspec": { "display_name": "Python 2", "language": "python", "name": "python2" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 2 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython2", "version": "2.7.6" } }, "nbformat": 4, "nbformat_minor": 0 }