Brake Power Testing in Internal Combustion Engines: Experiment Report
This report outlines the experimental procedure and results of a brake power test conducted on a four-stroke internal combustion engine. A hydraulic dynamometer was employed to measure output torque, while key data such as engine speed and temperature were recorded. The methodology section details the steps taken, including motoring the engine at varying temperatures to assess friction and pumping losses. Results are presented in tabulated form, alongside calculated values for brake power and torque. Conclusions discuss discrepancies between experimental and theoretical results.
Brake Power Testing in Internal Combustion Engines: Experiment Report
E N D
Presentation Transcript
I.C. ENGINES Practical No: 3 (22 Apr, 2014)
Report Writing • Title • Date • Object • Reason for carrying out the experiment and whether it s to prove some theory • Apparatus • Specification of engine
Report Writing • Apparatus • Specification of engine and equipment • Clear description if the apparatus used • Illustrated by simple diagrams and photos
Report Writing • Procedure • An account of things done before and during the experiment • Results • Record of all data • Reading taken before and during the experiment • Results should be in tabulated form
Report Writing • Results • Formula used foe the calculations and one specimen of each type of calculation should shown • Graphs drawn to show the results must be clearly marked with • Title • Date • Scales
Report Writing • Conclusions • An account of any incident or event during the experiment • Suggestions why the experiment and theoretical results do not agree • Do not always blame the equipment
Report Writing • Hints • Always write in past tense • Make no personal references • Examples • Weights were placed on the carrier • Reading were observed at two minutes intervals • Engine speed was increased • Temperature was constant
Brake Power Test • Apparatus • Hydraulic or electrical dynamometers are used for the testing • Dynamometer • Dynamometer can measure the output torque when driven by engine • Also measure input torque when used as electric motor to drive or rotate engine
Brake Power Test • Dynamometer • The motoring test if carried out when engine is cold gives a measure of the load which would be put on the starter motor when the engine is in the vehicle • Further tests can be carried out at various engines temperatures including extreme starting conditions and with different grades of lubricant oil
Brake Power Test • Dynamometer • Motoring the engine at normal working temperature enable the friction and pumping losses to be determine • For pumping losses engine can be relieved of its effective compression by removing the spark plugs or injector the remaining losses are frictional
Calculation for Power and Torque • Pb= 2 𝜋 FL ( rev/sec)
Calculation for Power and Torque • If = Constant say kc • Then
Example • A four cylinder , four stock engine has a piston area of 0.008 m2and stock of 0.025 m and it is tested against a dynamometer with torque arm of 0.4475 m, • P ( brake power) is given by • Torque in Nm by F • and b.m.e.p (break mean effective pressure) in kN/m2 by F • Where F = break load in N and , and are constants dependent upon the dimensions. • Find the values of , and
Example • Data • Formula • Sol • To find
Example • Sol • = 20
Example • Sol • F x 0.4775 ( Nm) • = 0.4775 • For • Work done = Force x Displacement( Nm) • = m.e.p x Area x Stock ( Nm) • = pAL • Work done / sec = p x A x L x S ( no of stocks)
Example • Sol • i.m.e.p= work done / sec • Indicated Power (Pt) = p x L x Ax S • b.m.e.p = 𝜂 Pt
Example • Sol • Now Brake Power = = • = 1500
