Problems on Testing and Performance of ICE PDF

PROBLEMS ON TESTING AND PERFORMANCE OF I.C. ENGINES 1) In a test on a single cylinder 4 stroke cycle gas engine with explosion in every cycle, the gas consumption given by the meter was 0.216 m3 /min, the pressure and temperature of the gas being 80 mm of water and 200C respectively. Air consumptio...

PROBLEMS ON TESTING AND PERFORMANCE OF I.C. ENGINES 1) In a test on a single cylinder 4 stroke cycle gas engine with explosion in every cycle, the gas consumption given by the meter was 0.216 m3 /min, the pressure and temperature of the gas being 80 mm of water and 200C respectively. Air consumption was 2.75 kg/min, the temperature being 200C and barometer reads 750 mm of Hg. The bore of engine is 280 mm & stroke 500 mm & rpm 300. Find the volumetric efficiency of the engine referred to volume of charge at NTP. Take R of air 0.287 kJ/kg-K. 2) During the trial of single cylinder, 4 stroke of oil engine, the following results were obtained: Cylinder dia. = 200mm Stroke = 400mm Mep = 6 bar Torque = 407 N-m Speed = 250 r.p.m. Oil consumption = 4 kg/hr C.V. of fuel = 43 MJ/kg Cooling water flow rate = 4.5 Kg/min Air used / Kg of fuel = 30 Kg Rise in cooling water temperature = 450 C Temp. of exhaust gas = 4200C Room temp. = 200C Mean specific heat of exhaust gases = 1kJ/kgK Specific heat of water = 4.18 kJ/kgK Barometric pressure = 1.01325 bar Find IP, BP, & draw heat balance sheet for the test in kJ/hr basis. 3) Obtain the cylinder dimensions of a twin cylinder two stroke I.C. Engine from the following data: Engine speed = 4000 rpm Volumetric efficiency = 77 % Mechanical efficiency = 75 % Fuel consumption = 10 lit/hr. Sp. Gr. of fuel = 0.73 A:F ratio = 18 Piston speed = 600 m/min IMEP = 5 bar Also determine the power output at STP conditions. Assume R for air = 0.287 kJ/kgK. 4) The following data is taken from a trial on 4 cylinder 4 stroke petrol engine, which is coupled to a hydraulic dynamometer at constant speed with full throttle Brake power with all cylinder working = 14.7 KW Brake power with cylinder No.1 cut out = 10.2 KW Brake power with cylinder No.2 cut out = 10.3 KW Brake power with cylinder No.3 cut out = 10.4 KW Brake power with cylinder No.4 cut out = 10.2 KW Petrol used = 5.44 Kg/hr C.V. =42000 KJ/Kg Diameter of cylinder = 8 cm Stroke of piston = 10 cm Clearance volume = 100 cc Determine: 1) The mechanical efficiency 2) Indicated thermal efficiency 3) Relative efficiency based on Indicated power 5) During a trial on 4 cylinder petrol engine running at 50 rev/s. The brake load was 267N when all cylinders were working, when each cylinder was cut out in turn, & speed returned to 50 rev/s, the brake readings were 178N, 187N, 182N & 182N. Using these readings, determine the brake power of engine & estimate indicated power & mechanical efficiency. For the brake, Brake power (kW) = FN/455, where F = brake load in Newton & N = rev/s. The following results were also obtained during the trial. Fuel consumption = 0.568 liter in 30 sec. Specific gr. of fuel = 0.72 Calorific value of fuel = 43000 KJ/Kg A:F ratio = 14:1 Exhaust temp. = 7600C Sp. heat capacity of Exhaust gas = 1.015 KJ/Kg K Cooling water inlet temp. = 180C Cooling water outlet temp. = 560C Cooling water flow rate = 0.28 Kg/s Ambient temp = 210C From these result, draw up an energy balance KJ/s & as a % of energy supplied. 6) Test on single cylinder oil engine with bore 30 cm & stroke 40 cm working on 4-stroke cylinder, the following observations were made: Duration of trial = 1 hr Total fuel consumption = 8.5 liters Sp. gravity of fuel = 0.83 Calorific value = 44500 kJ/kg Total revolutions = 12000 Gross IMEP = 6.35 bar and Pumping IMEP = 0.35 bar Brake load =160 Kg Spring balance reading = 10 kg Brake drum diameter = 180 cm Rope diameter = 3 cm Jacket cooling water collected = 550 Kg Water inlet & outlet temperatures 150C & 600C respectively. Total air consumption = 360 kg Specific heat of exhaust gas = 1.01 kJ/kg Exhaust gas outlet temperature = 3000C Find: i) Mechanical efficiency ii) Draw heat balance sheet on minute basis, Write the remarks. 7) A four cylinder, four stroke engine of 100*120 mm cylinder size was tested at 1600 rpm & the following readings were obtained. Fuel consumption = 0.27 lit/min Specific gravity of fuel = 0.74 Net load on brake = 400 N Constant of dynamometer k = 20380 [BP (kW) = W(N) * N (rpm) / k ] Calorific value of fuel = 44 MJ/kg Assuming 80% mechanical efficiency, calculate: i) Brake thermal efficiency ii) Indicated thermal efficiency iii) BSFC iv) IMEP Q8) A four-cylinder petrol engine has bore of 5.7 cm & stroke of 9 cm. Its rated speed is 2800 rpm & it is tested at this speed against a brake which has torque arm of 0.356 m. The net brake load is 155 N & fuel consumption is 6.740 lit/hr. The Sp.gr of petrol used is 0.735 & it has low calorific value of 44200 kJ/kg. A Morse test is carried out & cylinders are cut out in the order 1,2,3 & 4 with corresponding brake loads of 111, 106.5, 104.2 & 111 Newton respectively. Calculate for this speed, engine torque, brake thermal efficiency, specific fuel consumption, mechanical efficiency & indicated mean effective pressures. 9) Obtain the cylinder dimensions of a twin cylinder, two stroke I.C. engine from the following data: Engine speed = 4000 rpm Volumetric efficiency = 77 % Mechanical efficiency = 75 % Fuel consumption = 10 lit/hr Sp.gr. of fuel = 0.73 Air - fuel ratio = 18 Piston speed = 600 m/min Imep = 5 bar Also, determine the power output at S.T.P. conditions. Assume R air = 0.287 KJ/Kg K 10) A six cylinder, gasoline engine operates on the four stroke cycle. The bore of each cylinder is 80 mm & stroke 100 mm. The clearance volume per cylinder is 70 cc. At a speed of 4000 rpm the fuel consumption is 20 Kg/hr & the torque developed is 150 Nm. Calculate: i) The brake power ii) The brake mean effective pressure iii) Brake thermal efficiency If the calorific value of fuel is 43000 KJ/Kg & relative efficiency on a brake power assuming the engine works on the constant volume cycle.  = 1.4 for air. 11) A single cylinder engine running at 1800 rpm develops a torque of 8 Nm. The indicated power of the engine is 1.8 kW. Find the loss due to friction power as the percentage of brake power. 12) A two-stroke diesel engine was subjected to motoring test. The wattmeter reading was 1.6 kW. The engine was then tested for one hour and following observations were noted: Observations: i) Net brake torque = 125 Nm ii) Engine rpm = 610 iii) Fuel consumption = 2.5 kg iv) Calorific value of fuel = 41000 kJ/kg v) Cooling water used = 825 kg vi) Temp rise of cooling water = 80C vii) Exhaust gas temp = 3500C viii) Room temp = 300C ix) Air fuel ratio = 32:1 x) Sp. heat of exhaust gas = 1.05 kJ/kgK Calculate: a) Brake power b) Indicate power c) Mechanical efficiency d) Indicated thermal efficiency e) Heat balance sheet on min and percentage basis. 13) A 4 cylinder, 4 stroke cycle engine having cylinder diameter 100 mm and stroke 120 mm was tested at 1600 rpm and the following readings were obtained: Fuel consumption = 0.27 lit/min Sp. Gr. of fuel = 0.74 BP = 31.4 kW Mechanical efficiency = 80 % Calorific value of fuel = 44000 kJ/kg Determine: i) BSFC ii) IMEP iii) Brake thermal efficiency 14) A single cylinder & two stroke cycle I.C. engine when tested, the following observations available: Area of indicator diag. = 3 sq. cm. Length of indicator diag. = 4 cm, Spring constant = 10 bar/cm Speed of engine = 400 r.p.m Brake drum perimeter = 3.77 m Dead wt on brake = 380 N Spring balance reading = 50 N Fuel consumption = 2.8 kg/hr CV = 42000 KJ/Kg Cylinder dia = 16 cm, Piston stroke = 20 cm Find : a) F.P b) Mechanical efficiency c) BSFC d) Brake thermal efficiency 15) Calculate the bore and stroke of a four stroke cylinder diesel engine designed to the following parameters: Brake power = 25 kW Speed = 300 rpm Fuel consumption = C=85 %, H=15% Lower CV of fuel = 41000 kJ/kg Air supplied = 25 % xcess Volumetric efficiency = 80 % at 1.01325 bar and 100C Mechanical efficiency = 0.98 Indicated thermal efficiency = 0.35 R for air = 0.287 kJ/kgK Stroke to bore ratio = 1:1.2 16) Following data refered to single cylinder four stroke diesel engine running at 1850 rpm which is fitted with a dynamometer whose constant is 1248 and BP is given by WN / costant (BP in kW, W in N and N in rps) Period of test = 40 min, Net brake load = 18.5 kg Fuel used = 832 cc, Sp gr. of fuel = 0.89 CV of fuel = 44000 kJ/kg, Diameter of orifice plate of air box = 2.3 cm Manometer reading of orifice plate = 5 cm of water, Discharge coefficient of orifice plate = 0.61, Cylinder diameter = 90 mm Stroke = 90 mm, Cooling water used = 321 kg, Rise in temp of cooling water = 9.30C, Sp. heat of exhaust gas = 1.006 kJ/kgK Atm air pressure = 101.325 kPa, Room temp = 250C, Exhaust gas temperature = 4150C Calculate: 1. Volumetric efficiency 2. BSFC 3. Heat balance sheet on second basis. 17) A 4 stroke gas engine has a cylinder diameter of 25 cm and stroke 45 cm. The effective diameter of brake is 1.6 m. The observations made in the test of the engine were as follows: Duration of test = 40 min Total no. of revolutions = 8080 Total no. of explosions = 3230 ( or No. of misfire or no. of missed cycles = 810) Net load on brake = 90 kg MEP = 5.8 bar Volume of gas used = 7.5 m3 Pressure of gas indicated on gas meter = 136 mm of water gauge Atmospheric temperature = 170C Calorific value of gas = 19 MJ/m3 at NTP Atm pressure = 760 mm of Hg Estimate: 1. IP 2. BMEP 3. Indicated thermal efficiency ******