Small Groups Discussion 2019.docx

SMALL GROUPS DISCUSSION COURSES

: MARINE DIESEL

DAY/DATE

: MONDAY, MARCH 18 2019

DURATION

: 200 MENITS (100 MENITS DISCUSSION & 100 MENITS WRITE REPORT)

PROPERTIES

: WORKING IN A GROUP

1. 2. 3. 4. 5.

What are the differences between a diesel and gasoline two stroke cycle engine? How does a 4-stroke diesel engine works and how does a 2-stroke diesel engine works? What are the advantages and disadvantages of diesel engines? What do you know about lean mixture and rich mixture? Determine the air-fuel ratio, equivalence ratio and the air flow rate if: The concentration of O2 in the exhaust gases is 6% mole of oxidation of diesel fuel as much as 180 kg / hour. 6. A Diesel Engine has compression ratio 18 and a peak temperature of 2537 OC. Using an air Standard cycle analysis, estimate the work per unit mass of air, the thermal efficiency, the combustion pressure, and the cutoff ratio. 7. An Ideal Diesel Cycle with air as working fluid has a compression ratio of 18 and a catoff ratio of 2. At the beginning of the compression process, the working fluid is at 100 kPa, 27 OC , and 1917 Cm3. Utilizing the cold air standard assumption, determine: a. the temperature and pressure of air at the end of each process, b. The network output and the thermal efficiency, c. the mean effective pressure. 8. An eight-cylinder four-stroke-cycle engine has a bore of 10 cm and a stroke of 12 cm. At a shaft speed of 53 rps, the brake power is 300kW and the mechanical efficiency is 85%. Fuel with a heating value of 40,000kJ/kg is supplied at a rate of 40 kg/hr. What are the engine displacement, BMEP, brake torque, and indicated specific fuel consumption in kg/kW-hr?

EXCERSICE: ENGINE PERFORMANCE EXPERIMENT DATA a. b. c. d. e. f. g.

CONSTRUCTION : Inline 3 cylinder 4 stroke Diameter of Cylinder(D) : 180 mm Stroke (s) : 230 mm Volume of Stroke(VL) : 0.01755m3 (17.55L) Mass of Fuels : 50 cc The length of sleeve loading on the dynamometer = 2.07 m The fuel is Diesel Oil : 1. LHV=41800 KJ/kg 2. Density=830kg/m3

Fig.1: Engine Set up EXPERIMENT RESULT Speed 300 rpm Brake Force (N)

Speed 400 rpm

Times (s)

Speed 500 rpm

Brake Force (N)

Times (s)

Brake Force (N)

Times (s)

10

89

10

84

1

10

2

30

90

30

80

35

75

3

50

80

50

70

55

66

4

65

75

70

61

75

55

5

75

64

90

50

95

40

6

85

53

110

39

115

30

7

95

42

130

26

135

19

Task of Work: 1. Calculate all the data in accordance with the purposes 2. Make a graphics:

a. b. c. d. e. f. g.

Power vs SFC at a constant speed Power vs thermal efficiency at a constant speed Power vs BMEP at a constant speed SFC vs rpm at full load Thermal efficiency at full load BMEP vs rpm at constant power Make a diagram of an envelope engine