1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
{
"metadata": {
"name": "",
"signature": "sha256:0edb003d2406dbd42a27924dc90436706150dd4044705ed46aaf76f3c5aa44bf"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 18 : Super Charging"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 18.1 Page no : 327"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\t\t\t\t\t\n",
"#Input data\n",
"n = 6.\t\t\t\t\t#Number of cylinders\n",
"d = 9.\t\t\t\t\t#Bore in cm\n",
"l = 10.\t\t\t\t\t#Stroke in cm\n",
"N = 2500.\t\t\t\t\t#Speed in r.p.m\n",
"Ta = 25.+273\t\t\t\t\t#Temperature of air entering the compressor in K\n",
"q = 16800.\t\t\t\t\t#Heat rate in kcal/hour\n",
"T = 60.+273\t\t\t\t\t#Temperature of air leaving the cooler in K\n",
"p = 1.6\t\t\t\t\t#Pressure of air leaving the cooler in kg/cm**2\n",
"t = 14.5\t\t\t\t\t#Engine torque in kg.m\n",
"nv = 75.\t\t\t\t\t#Volumetric efficiency in percent\n",
"nm = 74.\t\t\t\t\t#Mechanical efficiency in percent\n",
"R = 29.27\t\t\t\t\t#Characteristic gas constant in kg.m/kg.K\n",
"Cp = 0.24\t\t\t\t\t#Specific heat at constant pressure n kcal/kg.K\n",
"\n",
"\t\t\t\t\t\n",
"#Calculations\n",
"BHP = (2*3.14*N*t)/4500\t\t\t\t\t#Brake horse power in B.H.P\n",
"IHP = (BHP/(nm/100))\t\t\t\t\t#Indicated horse power in I.H.P\n",
"pm = ((IHP*4500)/((l/100)*(3.14/4)*d**2*(N/2)*n))\t\t\t\t\t#Mean effective pressure in kg/cm**2\n",
"Vs = (n*(3.14/4)*(d/100)**2*(l/100)*(N/2))\t\t\t\t\t#Swept volume in m**3/min\n",
"Va = (Vs*(nv/100))\t\t\t\t\t#Aspirated Volume of air into engine in m**3/min\n",
"ma = (p*10**4*Va)/(R*T)\t\t\t\t\t#Aspirated mass flow into the engine in kg/min\n",
"mcdT = ((BHP*4500/427)/Cp)\t\t\t\t\t#Product of mass flow rate and change in temperature\n",
"msdT = ((q/60)/Cp)\t\t\t\t\t#Product of mass flow rate and change in temperature\n",
"x = (mcdT/msdT)\t\t\t\t\t#Ratio\n",
"T2 = ((Ta-(x*T)))/(1-x)\t\t\t\t\t#Temperature in K\n",
"mc = (msdT/(T2-T))\t\t\t\t\t#Air flow in kg/min\n",
"\n",
"\t\t\t\t\t\n",
"#Output\n",
"print 'a) the mean effective pressure is %3.2f kg/cm**2 \\\n",
"\\nb) the air consumption is %3.3f kg/min \\\n",
"\\nc) the air flow into the compressor is %3.2f kg/min'%(pm,ma,mc)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"a) the mean effective pressure is 6.45 kg/cm**2 \n",
"b) the air consumption is 5.871 kg/min \n",
"c) the air flow into the compressor is 30.14 kg/min\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 18.2 Page no : 328"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\t\t\t\t\t\n",
"#Input data\n",
"IMEP = 10.\t\t\t\t\t#Indicated mean effective pressure in kg/cm**2\n",
"x = 20.\t\t\t\t\t#Mixture strength 20% richer math.tan chemically correct\n",
"pIMEP = 0.41\t\t\t\t\t#Pumping Indicated mean effective pressure in kg/cm**2\n",
"p1 = 0.97\t\t\t\t\t#Charge pressure at the beginning of compression in kg/cm**2\n",
"T1 = 100.+273\t\t\t\t\t#Charge temperature at the beginning of compression in K\n",
"pm = 0.91\t\t\t\t\t#Mean pressure during the conduction stroke in kg/cm**2\n",
"bn = 70.\t\t\t\t\t#Blower adiabatic efficiency in percent\n",
"T2 = 50.\t\t\t\t\t#Temperature of the charge after delivery by the blower in degree C\n",
"dp = 0.07\t\t\t\t\t#Pressure drop in kg/cm**2\n",
"pi = 1.47\t\t\t\t\t#Charge pressure in the cylinder during the induction stroke in kg/cm**2\n",
"Ta = 15.+273\t\t\t\t\t#Atomspheric temperature in K\n",
"pa = 1.03\t\t\t\t\t#Atmospheric pressure in kg/cm**2\n",
"g = 1.4\t\t\t\t\t#Ratio of specific heats\n",
"\n",
"\t\t\t\t\t\n",
"#Calculations\n",
"T2x = ((((pi/pa)**((g-1)/g)-1)/(bn/100))+1)*Ta+T2\t\t\t\t\t#Temperature in K\n",
"rIMEP = ((pi/pa)*(T1/T2x))\t\t\t\t\t#Ratio of I.M.E.P\n",
"gIMEP = (rIMEP*IMEP)\t\t\t\t\t#Gross I.M.E.P in kg/cm**2\n",
"nsIMEP = (gIMEP+(pi-pa))\t\t\t\t\t#Net I.M.E.P supercharged in kg/cm**2\n",
"nuIMEP = (IMEP-pIMEP)\t\t\t\t\t#Net I.M.E.P unsupercharged in kg/cm**2 \n",
"iIMEP = (nsIMEP-nuIMEP)\t\t\t\t\t#Increase in I.M.E.P in kg/cm**2\n",
"pei = (iIMEP*100)/nuIMEP\t\t\t\t\t#Percentage increase\n",
"\n",
"\t\t\t\t\t\n",
"#Output\n",
"print 'Percentage increase in the net I.M.E.P due to supercharging is %3.1f percent'%(pei)\n",
"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Percentage increase in the net I.M.E.P due to supercharging is 49.9 percent\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 18.3 Page no : 331"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"\t\t\t\t\t\n",
"#Input data\n",
"l = 4.5\t\t\t\t\t#Capacity in litres\n",
"P = 20.\t\t\t\t\t#Power in H.P per m**3 of free air induced per minute\n",
"N = 1700.\t\t\t\t\t#Speed in r.p.m\n",
"nv = 75.\t\t\t\t\t#Volumetric efficiency in percent\n",
"Ta = 27.+273\t\t\t\t\t#Atomspheric temperature in K\n",
"pa = 1.03\t\t\t\t\t#Atmospheric pressure in kg/cm**2\n",
"pr = 1.75\t\t\t\t\t#Pressure ratio\n",
"ie = 70.\t\t\t\t\t#Isentropic efficiency in percent\n",
"nm = 75.\t\t\t\t\t#Mechanical efficiency in percent\n",
"g = 1.4\t\t\t\t\t#Ratio of specific heats\n",
"nb = 80.\t\t\t\t\t#Efficiency of blower in percent\n",
"R = 29.27\t\t\t\t\t#Characteristic gas constant in kg.m/kg.K\n",
"Cp = 0.24\t\t\t\t\t#Specific heat at constant pressure in kJ/kg.K\n",
"J = 427.\t\t\t\t\t#Mechanical equivalent of heat in kg.m/kcal\n",
"\n",
"\t\t\t\t\t\n",
"#Calculations\n",
"Vs = (l/1000*(N/2))\t\t\t\t\t#Swept volume in m**3/min\n",
"uVs = ((nm/100)*Vs)\t\t\t\t\t#Unsupercharged swept volume in m**3/min\n",
"dp = (pr*pa)\t\t\t\t\t#Blower delivery pressure in kg/cm**2\n",
"Tc = (Ta*pr**((g-1)/g))\t\t\t\t\t#Temperature after isentropic compression in K\n",
"dT = (Ta+(Tc-Ta)/(ie/100))\t\t\t\t\t#Blow delivery temperature in K\n",
"Va = (Vs*(dp*Ta)/(pa*dT))\t\t\t\t\t#Equivalent volume at free air condition in m**3/min\n",
"iiv = (Va-uVs)\t\t\t\t\t#Increase in the induced volume in m**3/min\n",
"iIHP = (P*iiv)\t\t\t\t\t#ncrease in I.H.P \n",
"iBHP = (iIHP*(nm/100))\t\t\t\t\t#Increase in B.H.P\n",
"ma = (dp*10**4*Vs)/(R*dT)\t\t\t\t\t#Mass of air delivered by blower in kg/min\n",
"HP = (ma*Cp*(dT-Ta)*J)/(4500*(80./100))\t\t\t\t\t#H.P required for blower\n",
"nibhp = (iBHP-HP)\t\t\t\t\t#Net increse in engine b.h.p\n",
"pei = (nibhp/(P*uVs))*100\t\t\t\t\t#Percentage increase\n",
"\n",
"\t\t\t\t\t\n",
"#Output\n",
"print 'Percentage net increase in B.H.P is %3.1f percent'%(pei)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Percentage net increase in B.H.P is 42.1 percent\n"
]
}
],
"prompt_number": 5
}
],
"metadata": {}
}
]
}
|
