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Exhaust emissions are well known to have adverse impacts on human health. Studies have demonstrated that there is an association between ambient particulate matter (PM) levels and various harmful cardiopulmonary conditions. Soot exhaust from diesel engines can be a significant contributor to airborne pollutants. A key component in PM level control for a diesel engine is a diesel particulate filter (DPF). This device traps soot while allowing other exhaust gases to pass unhindered. However, the performance of diesel particulate filters can change with increasing soot loadings and thus may require regeneration or replacement. Improved understanding of diesel particulate filters is dependent upon the knowledge of the actual soot loading and the soot distribution within the DPF. Neutron radiography (NR) has been identified as an effective means of non-destructively identifying hydrogen or carbon adsorbed in PM.

A key component in pollution control for a diesel engine is a diesel particulate filter (DPF). However, the performance of a diesel particulate filter will change with increasing soot loadings and thus may require regeneration. Improved understanding of diesel particulate filters is dependent upon knowledge of the local soot deposition distribution within the DPF. Neutron radiography (NR) has been identified as an effective means of non-destructively identifying hydrogen or carbon based components of particulate matter (PM). In this work, neutron radiography is used to measure multi-dimension soot deposition profiles of DPFs containing diesel soot loadings of 1g to 5g. The results show non-uniform axial, radial, and azimuthal soot distributions. The non-uniformity also increases with soot loading. The capability of neutron radiography to visualize soot multi-dimension distribution measurements has been demonstrated.

An investigation was performed to characterize the effect of the short twisted-tape inserts on the performance of EGR cooling devices for diesel engine applications. The results showed that the addition of the twisted-tape insert reduced the soot deposition and the blockage of the entrance region observed in the cooling devices tested without inserts. The addition of the inserts improved the thermal performance of the cooling devices for lower mass flow rates per tube with a relatively intermediate penalty of the long-time pressure drop build-up. At high flow rates, there was only smaller improvement of the heat transfer and a larger pressure drop penalty was observed. The results suggested that the addition of short twisted-tape inserts could be used to improve some current under performing designs of cooling devices. Optimization in terms of the tape-to-tube length ratio, tube diameter, and number of tubes is required in future studies for higher potential EGR rates.

An experimental investigation was conducted to characterize the operational transients of a small-scale 6-tube exhaust gas recirculation (EGR) cooling device, designed to simulate operating conditions of commercial devices, for a wide range of exhaust mass flow rates and different coolant temperatures. The transient pressure drop across the device and the thermal performance were measured for exhaust mass flow rates varying over a full range typically used in commercial devices. The coolant temperatures tested ranged from 25 °C to 55 °C. The temperature distribution on the outer shell surface of the small-scale EGR cooling device was also measured periodically using a thermal imaging camera to characterize the secondary side flow in the experiments. The results show that both the exhaust mass flow rate and the coolant temperature had a significant influence on the transient performance of the 6-tube EGR cooling device.

An investigation was performed to characterize the effect that the particulate matter in diesel exhaust gas has on the performance of the exhaust gas recirculation (EGR) cooling devices used in the EGR systems for diesel engines. The tests were performed by exposing a small-scale device designed to model commercial devices. It was found that the fouling caused by the diesel exhaust had a significant impact on the performance of the device during 12 hours of operation, increasing the thermal resistance by 150% and the pressure drop by 200%. The change in the performance on consecutive tests was cumulative, although it was found that the performance of the device did improve slightly between tests.

A non-destructive neutron radiography technique was used to measure the thickness of diesel soot deposited in the tubes of exhaust gas recirculation (EGR) cooling devices. Measurements were performed to characterize the fouling in single-tube and three-tube devices for laminar and turbulent flows. Measurements were also performed to characterize the effect that the design of the inlet header had on the deposition characteristics in the device. The analysis of the neutron images showed that the soot deposition in the single-tube device occurred at a faster rate for a turbulent flow than for a laminar flow. The deposition thickness decreased along the tubes for both flow regimes. More soot deposited in the center tube of the three-tube bundle for the expansion angle 45° inlet header suggesting there was an uneven distribution of the exhaust gas flow in the tube bundle.