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It is well known that most of the emissions from TWC cars are emitted during the cold start period. These emissions increase considerably at decreased ambient temperatures. To reduce cold start emissions an engine block heater may be used. In this present study the effects on the exhaust emissions of using a block heater were investigated. The exhaust was characterized by both regulated and some unregulated exhaust components. The car was tested according to the FTP-75 test procedure for regulated emissions at +22, +5 and -15°C ambient temperatures. At +5°C additional analysis of Polycyclic Aromatic Compounds (PAC) and 2,3,7,8-tetrachloro dibenzo-p-dioxin (TCDD) receptor affinity test was carried out. The test results showed reductions of CO and HC emissions when using a block heater. The reductions of these emissions were 60 and 65% respectively at the lowest ambient temperature investigated. NOx emissions were less affected and even increased marginally in some cases.

Number concentration of particles emitted by combustion engines has recently attracted attention, due to the fact that particles of the size range found in tail pipe emissions are suspected of being hazardous to human health. This paper describes the application of an Electrical Low Pressure Impactor (ELPI) to the measurement of number concentrations of diesel exhaust particles. The size distribution of particles as fine as 30 nm is determined using the aerodynamic diameter as the characteristic dimension. Results were obtained on both the engine and chassis dynamometer, in real-time, for steady state and transient tests. Swedish Environmental Class 1 diesel fuel was used, having a sulfur content of less than 10 ppm wt. A scheme for the calculation of particle losses in the sampling system was developed, showing high penetration of particles under the conditions examined.