Question

Problem 6. Compute the brake mean effective pressure of a four-cylinder, two-stroke engine, 100 mm bore 125 mm stroke when it develops a torque of 490 Nm. Problem = 7. Find the brake thermal efficiency of an engine which consumes 7 kg of fuel in 20 minutes and develops a brake power of 65kW. The fuel has heating value of 42000 kJ/kg. Problem # 8. Find the mean piston speed of a diesel engine running at 1500 rpm. The engine has a 100 mm bore and L/d ratio is 1.5. Problem #9. A four-cylinder, four-stroke, spark-ignition engine has a bore of 80 mm and stroke of 80 mm. The compression ratio is 8. Calculate: (1) the cubic capacity of the engine and (ii) the clearance volume of each cylinder. What type of engine is this? Problem # 10. A single-cylinder, compression-ignition engine with a brake thermal efficiency of 30% uses high speed diesel oil having a calorific value of 42000 kJ/kg. If its mechanical efficiency is 80 per cent, calculate: (i) bsfc in kg/kWh (ii) isfc in kg/kWh Problem: on Reciprocating Engine Page 1 of 1

Answer 1

6: Problem d = 100 mm Ls 125 mm T = 490 Nm. = 361.405 lb-ft 75.4 x T C ft-16) BMEP (psi) (2 stroke) Vs (in) Vs = I d²x Vs = x 100?x 125 - = 981747.704 mm 59.909 in 75-4 X 361, 405 BMEP (psi) = 159.909 BMEP = 454, 855 Psi - 5136. (( - k Pa В МЕe CScanned with Camscanner

problem 7 : Bip bt = BP = 65 kw, fp = mg x cv FP = 7 kg 20x60 5 42000 * F.P = 245 KW. bt = 69 = 0. 265 3 245 1 l = 26.53% problem 8 t 2LN Mean speed = 60 d = 100 mm; Petr N = 1500 rpm = 1.5 LE 1.5*100 = 150 mm, Mean speed = 2X 150 X 1500 -= 7500 mmis 60 I mean speed = 7.5 mls) CS scanned with ÇamScanner

q = problem de 80 mm; L= 80 mm, Pc = 8 o cubic capacity = I d ²xL. =Vs = I x 80?x 80 3 CC = 402123.859 mm 208 culinder. C = 402.123 74 Tac = 1608.492 cm) 위 YE & V2 V-V2 = V - 402:12 3 8V2 - V2 = 402.123 clearance volume = V2 = 57.446 cm3 cSScanned with CamScanner

12 Hotel when th=1 * when > * when 4 FT + spune # square & short stroke over square * long stroke undee square. problem 10: ht = cv = 30.5. 42000 ks 1kg Imech – 80 % WKT, Bip bsfc = not = 1. mfx CV р, Р BP = "tx mq xcv bsfc = . Mocx sx CV 0.3 x 42000 bsfc = 7.9365 x 10 kg Tkw.s CS$cannelli baiskem Scammer 0.2857 Ugl kwih

mif note | С te = IP te n mech. = ite 0.3 0.8 = 0.375 I-P . i = 0.375 mg x CV lips 0.375 x mif x CV. isfc = mif 0.3758 m fx CV isfc = 0,375 X H2000 isfc = 6, 3492x103 kg/kw.s Liste = 0,2285 kg/kw.nl CScanned with CamScanner