Method for controlling dilution air

摘要

A method for controlling the dilution air supply to a partial flow dilution tunnel in a gas sampling system is provided. The gas sampling system is capable of testing and certifying internal combustion engines under transient conditions and includes a partial flow dilution tunnel, master and slave mass flow controllers and a transient dilution air flow controlling arrangement. The transient dilution air flow controlling arrangement measures the transient changes in intake air and varies the flow of diluent air to the partial flow dilution tunnel. By controlling the diluent air in this manner ensures that a particle sample can be taken at any time that is at a constant proportion to the exhaust flow rate.