Development of a micro-dilution tunnel system for in-use, on-board heavy-duty vehicle particulate matter emissions measurement

Abstract

A novel portable particulate matter measuring system was designed, developed and qualified. The heavy-duty engine Federal Test Procedure (FTP) requires the use of a full-flow tunnel to measure particulate emissions from diesel fueled engines. However, a full-flow tunnel based constant volume sampler (CVS) system is not only expensive to build and maintain, it also requires a large work space. The portable micro-dilution system that could be used for measuring on-board, in-use emissions from heavy-duty vehicles would cost significantly less. The micro-dilution tunnel operates on the same principle as a full-flow dilution tunnel. The added advantage of the proposed design is that unlike a full-flow tunnel, dilution ratios can be controlled very accurately. The micro-dilution tunnel system was designed to maintain a dilution ratio of at least four to one. Dilution ratios were determined by measuring the mass flow rates of the dilution air and dilute exhaust, and the difference of the two was equal to the raw exhaust mass flow rate. The design incorporates a novel (3.175 mm in diameter, and 0.254 m long) concentric stainless dilution tunnel, which was a porous stack sampler manufactured by Mott Corporation. The unique feature of the system is its use of a single pump for not only drawing the diluted exhaust out of the micro-dilution tunnel, but also supplying filtered and dry dilution air to the tunnel. The system was used to collect PM emissions data from two different engines, namely, Navistar T444E and Detroit Diesel Series 60. The engines were tested over several steady state and transient tests. The micro-dilution system was compared to West Virginia University's (WVU) Engine and Emissions Research Laboratory (EERL) full flow tunnel system. As expected, the particulate matter data correlated better with steady state than with transient tests. The particulate matter mass emission rates were within 14% for the steady state tests and within 17% for majority of the transient tests of the full-flow laboratory's PM mass emissions data. However, one transient test resulted in a 33% difference between the micro-dilution tunnel and the full-flow dilution tunnel. The test results indicate that modifications are necessary to the micro-dilution system before it is to be used for on-road PM emission measurements. iii ACKNOWLEDGEMENTS As my sixth year at West Virginia University comes to an end, I must say that all goods things must come to an end. There are several people who have played an important role during my graduate studies at WVU and I would like to try to thank each and every one of them. I must first thank Dr. Mridul Gautam for giving me the opportunity to attend graduate school. Thank you for being my advisor and friend. Your support has encouraged me to keep going and never give up. I also wish to thank my other committee members, Dr. Gary Morris and Dr. Greg Thompson for their continued support and influence throughout my graduate education. I would like to thank the most important people in my life, my family....

Measurements of the characteristics of particle emissions from a port fuel injection engine

“…Once it had been established that the dilution tunnel worked correctly and a test cycle was decided on, the next step was to refine operation of the tunnel. Previous dilution tunnels constructed by Wei et al 17 and Cirillo 19 utilised a heated transfer tube in order to minimise the thermophoretic particle losses. When the exhaust gas travels up the probe and into the much cooler transfer tube, the temperature gradient causes particles to migrate to the walls of the transfer tube, causing a decrease in the particle count according to equation (6) from the literature review.…”

“…Other partial-flow dilution tunnels operate at lower dilution ratios than those used by Wei et al, 17 e.g. the dilution tunnel operated by Kommer et al 18 at dilution ratios of 7-45, and the dilution tunnel operated by Cirillo 19 at a dilution ratio of 4.…”

“…Cirrillo 19 have been designed with different tunnel parameters ( Table 1). The dilution tunnels used by both Kommer et al 18 and Cirillo 19 have comparable tunnel flow rates with those used in the tunnel for this work, but their residence times, dilution ratios and tunnel volumes vary widely. Therefore, a design of a dilution tunnel for characterisation of particles emitted from PFI engines is still needed.…”

“…Wei et al 17 600-1700 50-1500 0.4-2 50.89 Kommer et al 18 10-60 7-45 9 2.55 Cirillo 19 8 4 0.02 2 3 10 -3…”

Real-time measurement of oxides of nitrogen from heavy-duty diesel engines

“…The inlet pressure was adjusted with a butterfly valve placed upstream of the LFE. A remote butterfly valve was placed in the exhaust piping close to the engine to adjust exhaust backpressure to the engine manufacturer's specifications [16].…”