System for determining number of particles

A system for determining a number of particles comprising

• an exhaust gas introduction port to introduce an exhaust gas of an engine,
• a dilution gas introduction port to introduce a dilution gas,
• a main flow channel whose one end is connected to the exhaust gas introduction port,
• a dilution gas flow channel whose one end is connected to the dilution gas introduction port and whose other end is connected to the main flow channel,
• a secondary diluter arranged at a connecting point of the main flow channel and the dilution gas flow channel or downstream of the connecting point,
• a primary diluter arranged upstream of the connecting point on the main flow channel such that a flow rate measuring device is not arranged between the secondary diluter and the primary diluter, and that dilutes the exhaust gas of the engine,
• a dilution gas flow rate control part arranged in the dilution gas flow channel and that controls a flow rate of the dilution gas introduced into the secondary diluter,
• a particle number measuring unit, having a function of a constant flow rate, arranged downstream of the secondary diluter through a valve and that measures a number of solid particles in the diluted exhaust gas,
• a bypass flow channel that bifurcates from between the secondary diluter and the particle number measuring unit in the main flow channel and in which a constant flow rate unit and a valve are arranged,
• a suction pump connected downstream of a converging point of the main flow channel and the bypass flow channel in order to introduce the exhaust gas into the main flow channel and the bypass flow channel, and
• an information processing unit that receives the dilution gas flow rate controlled by the dilution gas flow rate control part and a unit flow rate as being a flow rate flowing in the particle number measuring unit and a set flow rate of the constant flow rate unit in the bypass flow channel, and calculates a dilution factor of the exhaust gas based on the dilution gas flow rate and a total of the unit flow rate and the set flow rate.