Chapter7-Engine Power and Fuel Consumption¶

Ex1-pg109¶

In :
#given
import math
#find the brake horse power
N=1150.
Wt=151.
l=4.
Wo=22.
#finding netforce
#f=Wt-Wo
F=Wt-Wo
#then as
R=4.
#calculating Brake horse power
Bhp=F*R*N/(5250.)
print"%s %.2f %s"%("braking horse power",Bhp,"bhp")
braking horse power 113.03 bhp

Ex2-pg111¶

In :
#given
#find out what is torque produced by and engine
N=850.
bhp=62.
#by writting terms in equation
#5250 is dividing equation
T=5250*bhp/(N)
print"%s %.2f %s"%("torque produced by an engine",T,"lb-ft")
torque produced by an engine 382.94 lb-ft

Ex3-pg112¶

In :
#given
#find out brake mean effective pressure of a 6-cylinder
D=5**0.75
bhp=120.
l=8.
m=6.
n=1000.
bmep=1008000*((bhp/(D**2)*l*m*n))
print"%s %.2f %s"%("brake mean effective pressure",bmep/2.95,"psi")
brake mean effective pressure 176037824580.37 psi

Ex4-pg113¶

In :
#compute brake mean effective pressure
#given
T=350.
D=4**0.25
L=5
M=4
#bmep for 4-cycle engine=192*t
bmep=192*(T/(D**2)*L*M)
#bmep for 2-cycle engine
bmep2=bmep/2
print"%s %.2f %s"%("bmep for 4-cycle",bmep,"psi")
print"%s %.2f %s"%("bmep for 2-cycle",bmep,"psi")
bmep for 4-cycle 672000.00 psi
bmep for 2-cycle 672000.00 psi

Ex5-pg114¶

In :
#given
#find out mechanical efficency of an engine
bhp=57.
ihp=19.
ihp1=ihp+bhp

#computing according to equtaion
Me=(bhp/ihp1)*100.
print"%s %.2f %s"%("mechanical efficency",Me,"percent")
mechanical efficency 75.00 percent

Ex6-pg115¶

In :
#find the mechanical efficency of the diesel engine
#fid we set forth constant
fhp=19
bhp=57/2.
ihp=bhp+fhp
Bhp=(bhp/ihp)*100
print"%s %.2f %s"%("mechanical efficeny",Bhp,"bhp")
mechanical efficeny 60.00 bhp

Ex7-pg117¶

In :
#find the brake thermal efficency of an engine
#given
w=16.2
t=20.
p=126.
q=19300.
#during 20 minutes period of the test 126 bhp for a period 1/3 hour 126*(1/3.)
btu=42.*2544.
hi=16.2*19300.
bth=(btu/hi)*100.
print"%s %.2f %s"%("brake thermal efficency",bth,"percent")
brake thermal efficency 34.17 percent

Ex8-pg118¶

In :
#find the brake thermal efficency
#given
f=0.44
q=19500
#for each bhp output is 2544
hi=f*q
bth=(2544./hi)*100.
print"%s %.2f %s"%("brake thermal efficency",bth,"bhp")
brake thermal efficency 29.65 bhp

Ex9-pg118¶

In :
#find fuel consumption when using fuel 18
#given
bth=38.
#calculating heat input
#1 bhp 2544
hi=(2544./bth)*100.
print"%s %.2f %s"%("heat input",hi,"btu per hp")
F=hi/18390.
print"%s %.2f %s"%("fuel consumption",F,"lb")
heat input 6694.74 btu per hp
fuel consumption 0.36 lb