Basic Mechanical Engineering (3110006)

Winter-2019

Question-4c

BE | Semester-1 Winter-2019 | 03-01-2020

Q4) (c)

The following readings were observed during a test on Two Stroke Single Cylinder Diesel engine:
Bore = 22 cm Stoke = 28 cm Speed = 350 rpm Net brake load = 65 kg Effective brake drum diameter = 100 cm Mean Effective Pressure = 3 bar Fuel consumption = 4 kg/h Calorific value of fuel = 43 MJ.
Calculate: (1) Indicated Power (2) Brake Power (3) Mechanical Efficiency (4) Brake thermal Efficiency

Given data $d = 22 cm = 0.22 m$
$l = 28 cm = 0.28 m$
$N = 350 rpm$
$W_{net} = 65 kg$
$D_{eff} = 100 cm = 1 m$
$R_{eff} = 0.5 m$
$p_{m} = 3 bar = 300 kPa$
$m_{f} = 4 kg / Hr$
$CV = 43 MJ = 43000 kJ$

To Find : $IP = ?, BP = ?, η_{m} = ?, η_{bth} = ?$

Now,

$IP = \frac{p_{m} l A N}{60}$

$IP = \frac{300 \times 0.28 \times \frac{π}{4} {(0.22)}^{2} \times 350}{60}$

$IP = 18.626 kW$

Now,

$BP = \frac{2 π N T}{60}$

$BP = \frac{2 π N W_{net} R_{eff}}{60}$

$BP = \frac{2 π \times 350 \times 65 \times 9.81 \times 0.5}{60}$

$BP = 11.685 kW$

Now,

$η_{m} = \frac{BP}{IP}$

$η_{m} = \frac{11.685}{18.626}$

$η_{m} = 0.6273$

$η_{m} = 62.73 %$

Now,

$η_{bth} = \frac{BP}{\frac{m_{f}}{3600} \times CV}$

$η_{b t h} = \frac{11.685}{\frac{4}{3600} \times 43000}$

$η_{b t h} = 0.2445$

$η_{b t h} = 24.45 %$

Basic Mechanical Engineering (3110006)

Q4) (c)

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