{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 05:First law applied to Flow Processes" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.1:pg-97" ] }, { "cell_type": "code", "execution_count": 1, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.1\n", "\n", " The rate of work input is 116.0 kW\n", "\n", " The ratio of the inlet pipe diameter and outet pipe diameter is 0.0 \n" ] } ], "source": [ "# Part(a)\n", "import math\n", "V1 = 0.95 # Inlet volume flow rate in m**3/kg\n", "\n", "P1 = 100 # Pressure at inlet in kPa\n", "\n", "v1 = 7 # velocity of flow at inlet in m/s\n", "\n", "V2 = 0.19 # Exit volume flow rate in m**3/kg\n", "\n", "P2 = 700 # Pressure at exit in kPa \n", "\n", "v2 = 5 # velocity of flow at exit in m/s\n", "\n", "w = 0.5 # mass flow rate in kg/s\n", "\n", "u21 = 90 # change in internal energy in kJ/kg\n", "\n", "Q = -58 # Heat transfer in kW\n", "\n", "W = - w*( u21 + (P2*V2-P1*V1) + ((v2**2-v1**2)/2) ) + Q # W = dW/dt \n", "\n", "print \"\\n Example 5.1\"\n", "\n", "print \"\\n The rate of work input is \",abs(W) ,\" kW\"\n", "\n", "#The answers given in textbook is wrong\n", "\n", "# Part (b)\n", "\n", "A = (v2/v1)*(V1/V2) # A = A1/A2\n", "\n", "d_ratio = math.sqrt(A) # d = d1/d2\n", "\n", "print \"\\n The ratio of the inlet pipe diameter and outet pipe diameter is \",d_ratio ,\" \"\n", "\n", "#The answers vary due to round off error\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.2:pg-98" ] }, { "cell_type": "code", "execution_count": 2, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.2\n", "\n", " The internal energy decreases by 20.0 kJ\n" ] } ], "source": [ "import math\n", "V1 = 0.37 # volume flow rate at inlet in m**3/kg\n", "\n", "P1 = 600# Inlet pressure in kPa\n", "\n", "v1 = 16 # Inlet velocity of flow in m/s\n", "\n", "V2 = 0.62 # volume flow rate at exit in m**3/kg \n", "\n", "P2 = 100# Exit pressure in kPa\n", "\n", "v2 = 270 # Exit velocity of flow in m/s\n", "\n", "Z1 = 32 # Height of inlet port from datum in m\n", "\n", "Z2 = 0 #Height of exit port from datum in m\n", "\n", "g = 9.81 # Acceleration due to gravity\n", "\n", "Q = -9 # Heat transfer in kJ/kg\n", "\n", "W = 135 # Work transfer in kJ/kg\n", "\n", "U12 = (P2*V2-P1*V1) + ((v2**2-v1**2)/2000) + (Z2-Z1)*g*1e-3 + W - Q # Change in internal energy in kJ\n", "\n", "\n", "\n", "print \"\\n Example 5.2\"\n", "\n", "print \"\\n The internal energy decreases by \",round(U12) ,\" kJ\"\n", "\n", "#The answers vary due to round off error\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.3:pg-99" ] }, { "cell_type": "code", "execution_count": 3, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.3\n", "\n", " The steam flow rate is 53.5854836932 Kg/s\n" ] } ], "source": [ "import math\n", "\n", "P1 = 4 # Boiler pressure in MPa\n", "\n", "t1 = 400 # Exit temperature at boiler in degree Celsius\n", "\n", "h1 = 3213 # Enthalpy at boiler exit in kJ/kg\n", "\n", "V1 = 0.073 # specific volume at boiler exit in m**3/kg\n", "\n", "P2 = 3.5 # Pressure at turbine end in MPa\n", "\n", "t2 = 392 # Turbine exit temperature in degree Celsius\n", "\n", "h2 = 3202 # Enthalpy at turbine exit in kJ/kg\n", "\n", "V2 = 0.084 # specific volume at turbine exit in m**3/kg\n", "\n", "Q = -8.5 # Heat loss from pipeline in kJ/kg\n", "\n", "v1 = math.sqrt((2*(h1-h2+Q)*1e3)/(1.15**2-1)) # velocity of flow in m/s\n", "\n", "A1 = (math.pi/4)*0.2**2 # Area of pipe in m**2\n", "\n", "w = (A1*v1)/V1 # steam flow rate in Kg/s\n", "\n", "\n", "\n", "print \"\\n Example 5.3\"\n", "\n", "print \"\\n The steam flow rate is \",w ,\" Kg/s\"\n", "\n", "#The answers vary due to round off error\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.4:pg-100" ] }, { "cell_type": "code", "execution_count": 4, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.4\n", "\n", " The amount of heat that should be supplied is 703.880549402 Kg/h\n" ] } ], "source": [ "import math\n", "h1 = 313.93 # Enthalpy of water at heater inlet in kJ/kg\n", "\n", "h2 = 2676 # Enthalpy of hot water at temperature 100.2 degree Celsius\n", "\n", "h3 = 419 #Enthalpy of water at heater inlet in kJ/kg\n", "\n", "w1 = 4.2 # mass flow rate in kg/s\n", "\n", "\n", "\n", "print \"\\n Example 5.4\"\n", "\n", "w2 = w1*(h3-h1)/(h2-h3)# Steam rate \n", "\n", "print \"\\n The amount of heat that should be supplied is \",w2*3600 ,\" Kg/h\"\n", "\n", "\n", "\n", "#The answers vary due to round off error\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.5:pg-100" ] }, { "cell_type": "code", "execution_count": 5, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.5\n", "\n", " The rate of heat transfer to the air in the heat exchanger is 1577.85 kJ/s\n", "\n", " The power output from the turbine assuming no heat loss is 298 kW\n", "\n", " The velocity at the exit of the nozzle is 552.358579186 m/s\n" ] } ], "source": [ "import math\n", "t1 = 15 # Heat exchanger inlet temperature in degree Celsius\n", "\n", "t2 = 800 # Heat exchanger exit temperature in degree Celsius\n", "\n", "t3 = 650 # Turbine exit temperature in degree Celsius\n", "\n", "t4 = 500 # Nozzle exit temperature in degree Celsius\n", "\n", "v1 = 30 # Velocity of steam at heat exchanger inlet in m/s\n", "\n", "v2 = 30# Velocity of steam at turbine inlet in m/s\n", "\n", "v3 = 60 # Velocity of steam at nozzle inlet in m/s\n", "\n", "w = 2 # mass flow rate in kg/s\n", "\n", "cp = 1005 # Specific heat capacity of air in kJ/kgK\n", "\n", "\n", "\n", "print \"\\n Example 5.5\"\n", "\n", "Q1_2 = w*cp*(t2-t1) # rate of heat transfer\n", "\n", "print \"\\n The rate of heat transfer to the air in the heat exchanger is \",Q1_2/1e3 ,\" kJ/s\"\n", "\n", "\n", "\n", "W_T = w*( ((v2**2-v3**2)/2) + cp*(t2-t3)) # power output from the turbine\n", "\n", "print \"\\n The power output from the turbine assuming no heat loss is \",W_T/1000 ,\" kW\"\n", "\n", "v4 = math.sqrt( (v3**2) + (2*cp*(t3-t4)) ) # velocity at the exit of the nozzle\n", "\n", "print \"\\n The velocity at the exit of the nozzle is \",v4 ,\" m/s\"\n", "\n", "#The answers vary due to round off error\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.6:pg-102" ] }, { "cell_type": "code", "execution_count": 16, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.6\n", "\n", " Velocity of exhaust gas is 541.409855832 m/s\n" ] } ], "source": [ "import math\n", "\n", "ha = 260 # Enthalpy of air in kJ/kg\n", "\n", "hg = 912 # Enthalpy of gas in kJ/kg\n", "\n", "Va = 270 # Velocity of air in m/s\n", "\n", "wf = 0.0190 # mass of fuel in Kg\n", "\n", "wa = 1 # mass of air in Kg\n", "\n", "Ef = 44500 # Chemical energy of fuel in kJ/kg\n", "\n", "Q = 21 # Heat loss from the engine in kJ/kg\n", "\n", "\n", "\n", "print \"\\n Example 5.6\"\n", "\n", "Eg = 0.05*wf*Ef/(1+wf) # As 5% of chemical energy is not released in reaction\n", "\n", "wg = wa+wf # mass of flue gas\n", "\n", "Vg = math.sqrt(2000*(((ha+(Va**2*0.001)/2+(wf*Ef)-Q)/(1+wf))-hg-Eg)) \n", "\n", "\n", "\n", "print \"\\n Velocity of exhaust gas is \",Vg ,\" m/s\"\n", "\n", "#Answer given in textbook is wrong\n", "\n" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Ex5.8:pg-103" ] }, { "cell_type": "code", "execution_count": 6, "metadata": { "collapsed": false }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", " Example 5.8\n", "\n", " The rate at which air flows out of the tank is 0.85 kg/h\n" ] } ], "source": [ "import math\n", "# Given that\n", "\n", "V = 0.12 # Volume of tank in m**3\n", "\n", "p = 1 # Pressure in MPa\n", "\n", "T = 150 # Temperature in degree centigrade\n", "\n", "P = 0.1 # Power to peddle wheel in kW\n", "\n", "print \"\\n Example 5.8\"\n", "\n", "u0 = 0.718*273 # Internal energy at 0 degree Celsius\n", "\n", "# Function for internal energy of gas\n", "\n", "def f1(t):\n", " u = u0+(0.718*t)\n", " pv = 0.287*(273+t)\n", " return (u,pv)\n", " \n", "U,PV=f1(T)\n", " \n", " \n", "hp = U+PV # At 150 degree centigrade\n", "m_a = P/hp\n", " \n", "print \"\\n The rate at which air flows out of the tank is \",round(m_a*3600,2) ,\" kg/h\"\n", "\n", "#The answers vary due to round off error\n", "\n", "\n", "\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": "2.7.11" } }, "nbformat": 4, "nbformat_minor": 0 }