Experimental Evaluation of the Indicated Mean Effective Pressure (IMEP) in a Spark-Ignited, Single-Cylinder Gasoline Engine
ME 331: Thermodynamics
Objective
The internal combustion engine currently used for Otto Cycle analysis in the Duke ME 331 laboratory relies on a tachometer-based system to record time-resolved data. This setup requires the assumption that data between time steps occurs at a constant angular velocity, which is inaccurate. As such, my group of 4 students sought to develop an experimental method to record data continuously and calculate the engine’s instantaneous Indicated Mean Effective Pressure (IMEP).
Outcome
Our group integrated a new quadrature encoder and DAQ device with test bench’s existing pressure sensor to directly measure the engine’s crank angle, eliminating the need for interpolation. From there, we developed a Python program to calculate key engine performance parameters, including IMEP. Comparison with the ideal Otto cycle revealed inefficiencies in both the encoder- and tachometer-based systems; however, the encoder was significantly more accurate, delivering a 36.3% reduction in error from the previously-used tachometer system.
Skills
CAD Modeling (SolidWorks)
Experimental Design
Sensor Integration & Data Acquisition
Data Analysis
Project Management
Collaboration
Technical Documentation
