An equivalence ratio measurement method for biogas diesel dual fuel engine

Abstract

A system of measuring equivalence ratio phi of biogas diesel dual fuel engine is established by 2 hot wire sensors of automobile. The relationship between real phi given by gas analysis in downstream of mixer and ratio of output voltage of the two sensors allows us to determine calibrated coefficient of the system. Equivalence ratio phi strongly depends on the opening level of throttle valve and on CH4 composition in biogas but it slightly depends on engine speed. Maximum brake power of the engine is obtained with a slightly rich mixture. As CH4 composition in biogas increases, phi corresponding to maximum brake power moves gradually toward phi =1. The results of this work can be applied to design an automatic control system for biogas diesel dual fuel engine.