The compression ratio for a six cylinder, 4-stroke, Diesel engine is 15:1. The bore is 130 mm and stroke 150 mm. The indicated thermal efficiency is 0.41 and the A/F is 18.5. The lower heating value of the fuel is 44 MJ/kg. The volumetric eff. for engine is 0.9. The mechanical friction power for engine is equivalent to 12.5% of the indicated power. The engine operates at 900 rpm and the atmospheric pressure and temperature are 100 kPa absolute and 25 °C respectively. Take (k=1.4, specific heat at constant pressure = 1 kJ/kgK) Determine: a)Brake power for the engine. b) Brake specific fuel consumption. c) Brake thermal efficiency

An Sl engine with a compression ratio rc = 10.1:1 operates on the air standard Otto cycle at 4500 RPM. Maximum temperature in the cycle is 2700 °K and maximum pressure is 8200 kPa. The pressure in the cylinder when the exhaust valve opens is 600 KPa and the exhaust pressure is 98 kPa. The exhaust valve effectively opens at 56° ÞBDC. Calculate: 1. Time of exhaust blowdown in sec 2. The average temperature of the exhaust during the exhaust stroke in °K 3. The maximum flow velocity through the exhaust valve at the start of the blowdown process assuming chocked flow conditions in (m/sec)

14 A six-cylinder SI engine with a compression ra tio of 10.5:1 oper ates on a four-stroke cycle at 3000 RPM. Air enters the cylinders at T = 110 F and P = 12.8 psia. The intake valve closes at 20° BDC and combustion starts when the spark plug fires at 15 6TDC. Con- necting rod length is 6.64 in. and crank offset is 1.66 in. Calculate: (a) Cylinder temperature at start of combustion using air-standard Otto cyde analysis ['F] (b) Cylinder temper ature when spark plug fires assuming compression doesn't start until intake valve closes. ['F]

Consider a normally-aspirated, four-stroke, spark-ignition, 1.8 L four-cylinder engine with a compression ratio of 10. The induction system uses a single throttle body, and the diameter of the throttle body is 42 mm. The air will enter the throttle body at P₁ = 80 kPa and T₁ = 290 K. The air will be throttled from the 80 kPa ambient pressure down to P₁ = 30 kPa in the intake manifold while the engine's crankshaft speed is 4200 rpm. Model the air as an ideal gas having constant specific heat, using 300 K values from Cengel's tables posted on Canvas. a) Find the temperature of the air in the intake manifold after the air is throttled from P₁ = 80 kPa to P₁ = 30 kPa (answer: T₁ = 288.91 K). b) Find the density and mass flow rate of the air in the intake manifold (answers: P₁ = 0.3618 kg/m³ and m = 0.02533 kg/s). The volume of air in a cylinder at the start of the compression process is , which is the largest volume in a cylinder. The compression ratio, r, is the ratio of the largest…