Förfarande för gasprovtagning samt därför avsedd utspädningstunnel

摘要

Emission gasses from an engine exhaust pipe are collected through an inlet of a dilution tunnel which is an elongated, hollow tube. The inlet is spaced from the exhaust pipe to also admit surrounding air. Ambient air and emissions are mixed in the tunnel by a screen in the tunnel. A probe in the tunnel diverts a portion of the mixture to gas analyzers. Prior to analysis the mixture may be condensed, filtered or otherwise processed. The analysis determines a CO/CO2 ratio which is used to determine the air/fuel ratio in the engine based on characteristics of the fuel. The air/fuel mixture of the engine is then adjusted to achieve desired performance.