1822 words - 7 pages

Performance Test of a Compression Ignition EngineMatthew Steven, 0503527AimTo investigate the fundamentals of a compression ignition (I.C.) engine with respect to performance by determining the efficiency and where losses occur.ObjectivesThe objective of this report is to:Measure the performance of a compression ignition engine.Measure the mechanical losses in the engine.Measure the heat losses.MethodAfter allowing the engine to warm up the fuel control was set to maximum. Initially starting with no-load, the dynamometer loading was increased and all data was recorded in the 'Observed Results' table (page 5) before increasing the load and repeating. My investigation of my results comprised 3 parts.Part A: Measure/Determine the performance of the compression ignition engine.Using my recorded results from the 'Observed Results' table, I calculated:Brake Power (kW)Brake Mean Effect of Pressure, (Bp) (kN/m2)Brake specific Fuel Consumption (L/kW - hr)Brake thermal efficiencyThese were then noted in 'Calculated Results: Table A' (Page 6).I then proceeded to construct graphs of Torque, Power, Brake Specific Fuel Consumption and thermal Efficiency against the Brake Mean Effective Pressure (B.M.E.P) (Pages 7 - 10).Part B: Measure/Determine the mechanical losses in the engine by extrapolating the Willans line.For part B I plotted a graph of Fuel Consumption versus the B.M.E.P which allowed me to estimate the mechanical losses in the engine (page 11).Part C: Measure/Determine the heat losses.From my observed results I was able to determine:Heat of combustion of fuel, H1Brake Power output, PHeat to exhaust, H2Heating to cooling water, Q1Other losses, Q2These values where noted in Calculated Results: Table B: Heat Losses (page 12). These values allowed me to further calculate the percentage values of where heat losses occurred and to plot the graph of Exhaust Cooling WaterPercentage Heat Losses against B.M.E.PTheoryAs engine speed was observed in revolutions per second (rps) it was necessary to convert this into revolutions per minute (rpm) to use in further calculations. This was achieved by multiplying the rps value by 60;Engine Speed, (rpm)Brake Power is the product of torque and engine speed (N). However calculation of Brake Power must take into account that the dynamometer has a related constant.Brake Power,The mean effective pressure (M.E.P) is the average pressure exerted on the combustion chamber during each power stroke. As a dynamometer was used whilst testing I must calculate the energy left at the flywheel (I.E. Brake Power), this denounces Brake Mean Effective Pressure (B.M.E.P).B.M.E.P is the force applied to the total number of combustion chambers, so it is necessary to take into account the number of chambers (n = 2) and the constant related to the number of strokes (k = 2 for a four stroke engine).Brake Mean Effective Pressure,Where: = Brake Power (kW), A = Area of piston surface, L = length of stroke, N = Engine speed.To allow accurate...

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