Study of the influence of compression ratio on the rate of heat release in small displacement Diesel engines

Guillermo E Valencia,Jorge Duarte Forero,Luis G Obregon

doi:10.17485/ijst/2018/v11i21/123236

Abstract

Background/Objectives: To make implementation of a thermodynamic diagnostic model to determine the rate of heat release in low displacement Diesel engines so that the performance of the combustion process can be quantified and sub-models of heat transfer can be adjusted; so that it can be applied in subsequent predictive modeling. Methods: With the pressure data in the combustion chamber and the set of variables composed of the pressure and temperature in the admission, fuel consumption, speed of rotation, injection pressure, compression ratio and environmental conditions, a thermodynamic model is defined. It allows quantifying how the heat release process occurs in the combustion process. Findings: The results allow verifying the influence of the compression ratio on the heat release process, finding that the rate of heat released increases with the increase of the variable under study. Likewise, it is verified that the most pronounced difference between the release rates for different compression ratios studied is in the premix combustion zone. Application: This methodology can be used for the process of optimization and redesign of thermal engines, to maximize the output power for the same fuel and operational conditions. Keywords: Combustion, Compression Ratio, Diesel, Engine, Heat Released, Thermodynamic Model

Highlights

The thermodynamic diagnostic models applied to internal combustion engines use, as input data, among others, the values of the pressure in the combustion chamber and the position of the crankshaft
It is evident that the influence of the compression ratio on the rate of heat released during combustion is significant
When the engine operates with atmospheric admission pressure, the change in the rate of heat released (DFQL) due to the compression ratio is more noticeable, especially in the first stage of combustion

Summary

Introduction

The thermodynamic diagnostic models applied to internal combustion engines use, as input data, among others, the values of the pressure in the combustion chamber and the position of the crankshaft. With these data and other measurements of average variables, the heat release rate (DFQL) is obtained as output, which is the basis of the combustion diagnosis. An experimental study profile is based on measurement results and direct visualization of the behavior of the processes in the engine in question In these models, the adjustment of the data obtained from the rate of heat release to a mathematical combustion model is required.

Methods

Findings

Discussion

Conclusion