MEASUREMENT AND SIGNAL RECONSTRUCTION OF TRANSIENT NITRIC-OXIDE EMISSIONS IN THE EXHAUST OF A TURBOCHARGED DIESEL-ENGINE

A well-developed technique, based upon a combined experimental and phe nomenological modeling approach, has been adopted for the measurement of nitric oxide (NO) emissions in a diesel engine exhaust under transi ent engine operation. The dynamic behavior of the chemiluminescent ana lyzer used for the measurement of NO emissions is characterized by a s ingle gas diffusion model followed by three pet-feet gas-mixing models . The response of the analyzer is obtained using a computer-controlled transient NO emission simulator which randomly generates a square-pul se train of NO gas and concurrently measures its signal output. Signal prediction and reconstruction analysis were performed which has demon strated the predictive and reconstructive capabilities of the phenomen ological analyzer model. On-line nitric oxide emission measurements we re obtained in a computer-controlled dynamic engine test bed having th ree different control modes and fuel injection timing settings. The re sults have shown that the transient nitric oxide concentration is very sensitive to the engine operating condition prior to the transients a s well to the amount of fuel injected into the combustion chamber at t he start of the transient operation.