Question

Following data refer to a four-stroke double-acting diesel engine having cylinder diameter 200 mm and piston stroke 350 mm. m.e.p. on cover side -6.5 bar m.e.p. on crank side = 7 bar Speed = 420 r.p.m. Diameter of piston rod = 20 mm Dead load on the brake = 1370 N Spring balance reading = 145 N Brake wheel diameter = 1.2 m Brake rope diameter = 20 mm Calculate the mechanical efficiency of the engine.

Answer 1

Formula used to calculate IP is as follows- (IP)erank = (Prep) crank x L xAxNxk X10 | where, A, - A crank = II (D²-dood) (Acrank = Effective area on Cronk End side) K= 1 ( because in four stroke Engine, in two rotation of crank per - Get one power stroke) Son A = Acrank = (0.22-0.02) B (0.04 - 0.0004) = π (0.0396 4 . A = A crank = 0.0311 m² Similarly, Az = A cover = Area of Cylinder on Cover end side - It D² Az = A covere = 0.03141 m2 Therefore, (IP) crank = 7x0.35% 0.0311 X420 X1 X10

Date: Page no: IP) crank = 26.67 kn And Pcover = Imep cover X LX A 2X NXK X10 where Az = A cover = 0.03141 (IP) covere = 6.5x0.35X0.03141 X 420 XL, X10 (IP) coveri = 25 kW Total Indicated Power So. IP = (IP).coves +( IP ) crank = .25 + 26.67 Therefore, IP = 51.67 kW Formula used to calculate BP is as follows- Now, Brake Power BP = (W-Ws) n (burt Dhe 60 x1000 where W = 1370, Ws = 145 Dbw = 1.2 Dbr = 0.02 BP = (1370 -145 t. (102+0.02) 420 60 X 100.0 BP = 32.86 kw!