{
"metadata": {
"name": "",
"signature": "sha256:43030cb407ee8b4a262c4ba255fecb3e020be8690e26722c194a6ec2d965f42c"
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"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 14 : Refrigeration Cycles"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.1 Page No : 587"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"T2 = 268.; \n",
"T1 = 308.;\n",
"\n",
"# Calculation\n",
"COP = T2/(T1-T2);\n",
"ACOP = COP/3; \t\t\t# Actual COP\n",
"Q2 = 29.; \t\t\t# in kW\n",
"W = Q2/ACOP;\n",
"\n",
"# Results\n",
"print \"Power required to derive the plane is %.0f kW\"%W\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Power required to derive the plane is 13 kW\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.2 Page No : 589"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"h1 = 236.04; s1 = 0.9322; s2 = s1;\n",
"P2 = 0.8; \t\t\t# in MPa\n",
"h2 = 272.05; h3 = 93.42; h4 = h3;\n",
"m = 0.06; \t\t\t# mass flow rate\n",
"\n",
"# Calculation\n",
"Q2 = m*(h1-h4);\n",
"Wc = m*(h2-h1);\n",
"Q1 = m*(h2-h4);\n",
"COP = Q2/Wc;\n",
"\n",
"# Results\n",
"print \"The rate of heat removal is %.2f kW\"%Q2\n",
"print \"Power input to the compressor is %.2f kW\"%Wc\n",
"print \"The heat rejection rate in the condenser is %.2f kW\"%Q1\n",
"print \"COP is %.3f\"%COP\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The rate of heat removal is 8.56 kW\n",
"Power input to the compressor is 2.16 kW\n",
"The heat rejection rate in the condenser is 10.72 kW\n",
"COP is 3.961\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.3 Page No : 589"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"h1 = 183.19; \n",
"h2 = 209.41; \n",
"h3 = 74.59; \n",
"h4 = h3;\n",
"T1 = 313.; \n",
"T2 = 263.;\n",
"W = 70000./3600; \t\t\t# Plant capacity in kW\n",
"\n",
"# Calculation\n",
"w = W/(h1-h4); \t\t\t# Refrigerant flow rate\n",
"v1 = 0.077;\n",
"VFR = w*v1;\n",
"T = 48.; \t\t\t# in degree\n",
"P2 = 9.6066; P1 = 2.1912;\n",
"rp = P2/P1; \t\t\t# Pressure ratio\n",
"Q1 = w*(h2-h3);\n",
"hf = 26.87; hfg = 156.31;\n",
"x4 = (h4-hf)/hfg;\n",
"COP = (h1-h4)/(h2-h1);\n",
"PI = w*(h2-h1);\n",
"COP = T2/(T1-T2);\n",
"COP_v = 4.14;\n",
"r = COP_v/COP;\n",
"\n",
"# Results\n",
"print \"Refrigerant flow rate is %.2f Kg/s\"%w\n",
"print \"Volume flow rate is %.4f m3/s\"%VFR\n",
"print \"Compressor discharge temperature is\",T,\"degree\"\n",
"print \"Pressure ratio is %.2f\"%rp\n",
"print \"Heat rejected to the condenser is %.2f kW\"%Q1\n",
"print \"Flash gas percentage is %.1f %%\"%(x4*100)\n",
"print \"COP is\",COP\n",
"print \"Power required to drive the compressor is %.2f kW\"%PI\n",
"print \"Ratio of COP of carnot refrigerator is %.3f\"%r\n",
"\n",
"# note : rounding off error is there."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Refrigerant flow rate is 0.18 Kg/s\n",
"Volume flow rate is 0.0138 m3/s\n",
"Compressor discharge temperature is 48.0 degree\n",
"Pressure ratio is 4.38\n",
"Heat rejected to the condenser is 24.14 kW\n",
"Flash gas percentage is 30.5 %\n",
"COP is 5.26\n",
"Power required to drive the compressor is 4.69 kW\n",
"Ratio of COP of carnot refrigerator is 0.787\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.4 Page No : 590"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\n",
"# Variables\n",
"h3 = 882.\n",
"h2 = 1034.;\n",
"h6 = 998.\n",
"h1 = 1008.;\n",
"v1 = 0.084;\n",
"\n",
"# Calculation and Results\n",
"h4 = h3-h1+h6; h5 = h4;\n",
"t4 = 25.+273;\n",
"print \"Refrigeration effect is\",h6-h5,\"kJ/kg\"\n",
"\n",
"m = 10.;\n",
"w = (m*14000)/((h6-h5)*3600); \t\t\t# in kg/s\n",
"print \"Refrigerant flow rate is %.2f kg/s\"%w\n",
"\n",
"v1 = 0.084;\n",
"VFR = w*3600*v1; \t\t\t# in kg/h\n",
"ve = 0.8; \t\t\t# volumetric efficiency\n",
"CD = VFR/(ve*60); \t\t\t# in m3/min\n",
"N = 900;\n",
"n = 2;\n",
"D = ((CD*4)/(math.pi*1.1*N*n))**(1./3); \t\t\t# L = 1.1D L = length D = diameter\n",
"L = 1.1*D;\n",
"print \"Diameter of cylinder is %.1f cm\"%(D*100)\n",
"print \"Length of cylinder is %.2f cm\"%(L*100)\n",
"COP = (h6-h5)/(h2-h1);\n",
"PI = w*(h2-h1);\n",
"print \"Power required to drive the compresor is %.2f kW\"%PI\n",
"print \"COP is %.2f\"%COP\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Refrigeration effect is 126.0 kJ/kg\n",
"Refrigerant flow rate is 0.31 kg/s\n",
"Diameter of cylinder is 10.8 cm\n",
"Length of cylinder is 11.85 cm\n",
"Power required to drive the compresor is 8.02 kW\n",
"COP is 4.85\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.5 Page No : 592"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\n",
"# Variables\n",
"P2 = 1554.3;\n",
"P1 = 119.5;\n",
"Pi = math.sqrt(P1*P2);\n",
"h1 = 1404.6; \n",
"h2 = 1574.3; \n",
"h3 = 1443.5; \n",
"h4 = 1628.1;\n",
"h5 = 371.7; h6 = h5; h7 = 181.5;\n",
"w = 30.; \t\t\t# capacity of plant\n",
"\n",
"# Calculation\n",
"m2_dot = (3.89*30)/(h1-h7);\n",
"m1_dot = m2_dot*((h2-h7)/(h3-h6));\n",
"Wc_dot = m2_dot*(h2-h1)+m1_dot*(h4-h3);\n",
"COP = w*3.89/Wc_dot;\n",
"\t\t\t# math.single stage\n",
"h1_ = 1404.6; h2_ = 1805.1;\n",
"h3_ = 371.1; h4_ = h3_;\n",
"m_dot = (3.89*30)/(h1_-h4_);\n",
"Wc = m_dot*(h2_-h1_);\n",
"COP_ = w*3.89/Wc;\n",
"IW = (Wc-Wc_dot)/Wc_dot;\n",
"ICOP = (COP-COP_)/COP_\n",
"\n",
"# Results\n",
"print \"Increase in work of compression is %.2f\"%(IW*100)\n",
"print \"Increase in COP for 2 stage compression is %.2f %%\"%(ICOP*100)\n",
"\n",
"# note : rounding error is there."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Increase in work of compression is 15.72\n",
"Increase in COP for 2 stage compression is 15.72 %\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.6 Page No : 593"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"tsat = 120.2+273\n",
"hfg = 2201.9;\n",
"T1 = 120.2+273;\n",
"T2 = 30.+273;\n",
"Tr = -10.+273;\n",
"\n",
"# Calculation\n",
"COP_max = ((T1-T2)*Tr)/((T2-Tr)*T1);\n",
"ACOP = 0.4*COP_max;\n",
"Qe = (20.*14000)/3600; \t\t\t# in KW\n",
"Qg = Qe/ACOP;\n",
"x = 0.9; \n",
"H = x*hfg;\n",
"SFR = Qg/H;\n",
"\n",
"# Results\n",
"print \"Steam flow rate required is %.4f kg/s\"%SFR\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Steam flow rate required is 0.0651 kg/s\n"
]
}
],
"prompt_number": 20
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.7 Page No : 594"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"T1 = 277.; \n",
"T3 = 273.+55;\n",
"rp = 3.; \t\t\t# Pressure ratio\n",
"g = 1.4; \n",
"cp = 1.005;\n",
"\n",
"# Calculation and Results\n",
"T2s = T1*(rp**((g-1)/g));\n",
"T2 = T1+(T2s-T1)/0.72\n",
"T4s = T3/(rp**((g-1)/g));\n",
"T34 = 0.78*(T3-T4s); \t\t\t# T3-T4\n",
"T4 = T3-T34;\n",
"COP = (T1-T4)/((T2-T1)-(T3-T4));\n",
"print \"COP of the refrigerator is %.2f\"%COP\n",
"P = (3.*14000)/(COP*3600)\n",
"print \"Driving power required is %.1f kW\"%P\n",
"m = (3.*14000)/(cp*(T1-T4));\n",
"print \"Mass flow rate is %.2f kg/s\"%(m/3600)\n",
"\n",
"# note: rounding off error is there."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"COP of the refrigerator is 0.25\n",
"Driving power required is 47.5 kW\n",
"Mass flow rate is 0.65 kg/s\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.8 Page No : 596"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"P1 = 2.4; T1 = 0+273;\n",
"h1 = 188.9; s1 = 0.7177; v1 = 0.0703;\n",
"P2 = 9; T2 = 60+273;\n",
"h2 = 219.37;\n",
"h2s = 213.27;\n",
"h3 = 71.93; h4 = h3;\n",
"v1 = 0.0703;\n",
"A1V1 = 0.6/60;\n",
"\n",
"# Calculation\n",
"m_dot = A1V1/0.0703;\n",
"Wc_dot = m_dot*(h2-h1);\n",
"Q1_dot = m_dot*(h2-h3);\n",
"COP = Q1_dot/Wc_dot;\n",
"nis = (h2s-h1)/(h2-h1);\n",
"\n",
"# Results\n",
"print \"Power input is %.2f kW\"%Wc_dot\n",
"print \"Heating capacity is %.2f kW\"%Q1_dot\n",
"print \"COP is %.3f\"%COP\n",
"print \"The isentropic compressor efficiency is %.2f %%\"%(nis*100)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Power input is 4.33 kW\n",
"Heating capacity is 20.97 kW\n",
"COP is 4.839\n",
"The isentropic compressor efficiency is 79.98 %\n"
]
}
],
"prompt_number": 26
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14.9 Page No : 597"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"# Variables\n",
"T1 = 275.; \n",
"T3 = 310.;\n",
"P1 = 1. ; P2 = 4.;\n",
"\n",
"# Calculation\n",
"T2s = T1*(P2/P1);\n",
"nc = 0.8;\n",
"T2 = T1 + (T2s-T1)*nc;\n",
"pr = 0.1;\n",
"P3 = P2-0.1;\n",
"P4 = P1+0.08;\n",
"PR = P3/P4;\n",
"\n",
"# Results\n",
"print \"Pressure ratio for the turbine is %.3f\"%PR\n",
"T4s = T3*(1./PR)**(0.286);\n",
"nt = 0.85;\n",
"T4 = T3-(T3-T4s)*nt;\n",
"COP = (T1-T4)/((442.26-T3)-(T1-T4));\n",
"print \"COP is %.3f\"%COP\n",
"\n",
"# note : rounding off error is there."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Pressure ratio for the turbine is 3.611\n",
"COP is 0.533\n"
]
}
],
"prompt_number": 14
}
],
"metadata": {}
}
]
}