Question

13. The bp of a four-cylinder engine is 30 with all cylinder firing and 20 with one cylinder cut.
The mechanical efficiency is
bp-30
(a) 60%
(b) 80%
(c) 75%
(a) none of the above

Answer 1

Answer:

option

(B)

Explanation:

Answer 2

Answer:

option 'C' is correct

Explanation:

$IP= BP_{total}-BP_{cutoff}$

for a 4-cylinder engine there will be four I.Ps i.e

$IP_{1}= BP_{tot}-BP_{1}=30-20=10\\IP_{2}= BP_{tot}-BP_{2}=30-20=10\\IP_{3}= BP_{tot}-BP_{3}=30-20=10\\IP_{4}= BP_{tot}-BP_{4}=30-20=10$

Now, Total IP of the engine is given by

$IP_{tot}=IP_{1}+IP_{2}+IP_{3}+IP_{4}\\IP_{tot}=10+10+10+10 =40$

Finally, the mechanical efficiency of the engine is

$\eta_{mech}=\frac{BP_{tot}}{IP_{tot}}\\ \eta_{mech}=\frac{30}{40}\\\\\eta_{mech}= 0.75$

$\eta_{mech}= 75 percent$

#SPJ3