Comparison of Different Dilution Methods for Measuring Diesel Particle Emissions

Figures & data

TABLE 1 Engine operating parameters in the experiments

Case	Power [kW]	Rpm	Torque [Nm]	T after exhaust manifold [°C]	T at dilution point [°C]	T(oil) [°C]
Low load	7.4	2200	32	190–195	180	100
High load	50.7	1400	346	420	370	100

FIG. 1 Schematics describing the different dilution setups applied in the experiments. (a) ED1 + ED2 and SS + ED, (b) PRD + ED and PRD.

FIG. 2 Schematics (not in scale) of the different diluters applied in this study. (a) Ejector diluter (ED), (b) partial flow diluter Smart Sampler (SS), (c) porous tube diluter (PRD).

TABLE 2 Engine load, dilution ratios, dilution temperatures, total particle number concentrations measured with DMA + CNC, and calculated count median diameters for different dilution systems

Dilution	Load	DR1 Tdil. [°C]	DR2 Tdil. [°C]	DRtot	Ntot [l/cm^3]	CMD [nm]	σg
ED1 + ED2	Low	10.5	10.3	108	3.48 × 10^7	33	1.82
		182	32
ED1 + ED2	Low	10.5	10.3	108	3.49 × 10^7	34	1.77
		182	32
ED1 + ED2	High	10.5	10.3	108	3.53 × 10^7	70	1.55
		185	32
ED1 + ED2	High	10.5	10.3	108	3.09 × 10^7	67	1.60
		185	32
PRD + ED	Low	7.8	7.5	58	2.47 × 10^7	32	1.84
		200	32, 25
PRD + ED	Low	7.8	7.5	58	2.78 × 10^7	38	1.72
		200	32, 25
PRD + ED	High	10.8	13.8	149	3.69 × 10^7	66	1.60
		200	25
SS + ED	Low	2.5	11.7	29	5.14 × 10^7	40	1.42
		52, 25	25
SS + ED	Low	3.1	11.7	36	6.48 × 10^7	35	1.44
		52, 25	25
SS + ED	Low	3.6	11.7	42	8.18 × 10^7	32	1.44
		52, 25	25
SS + ED	Low	4.1	11.7	48	9.72 × 10^7	30	1.43
		52, 25	25
SS + ED	Low	4.4	11.7	52	9.69 × 10^7	29	1.43
		52, 25	25
SS + ED	Low	4.7	11.7	56	1.07 × 10^8	28	1.43
		52, 25	25
SS + ED	Low	5.3	11.7	63	1.09 × 10^8	28	1.43
		52, 25	25
PRD	Low	10		10	5.19 × 10^7	40	1.43
		25
PRD	Low	13		13	4.81 × 10^7	46	1.34
		25
PRD	Low	20		20	2.77 × 10^7	36	1.51
		25
PRD	Low	30		30	3.73 × 10^7	36	1.53
		25
PRD	Low	42		42	2.93 × 10^7	38	1.53
		25
PRD	Low	51		51	2.73 × 10^7	38	1.55
		25
PRD	Low	63		63	2.54 × 10^7	40	1.52
		25
PRD	Low	73		73	2.48 × 10^7	38	1.56
		25
PRD	Low	85		85	2.44 × 10^7	37	1.58
		25
PRD	Low	97		97	2.61 × 10^7	40	1.52
		25
PRD	Low	167		167	2.12 × 10^7	42	1.53
		25
If two dilution temperatures are given the first refers to diluter and the second to dilution air temperature.

FIG. 3 Number size distributions measured with DMA + CNC for different dilution systems and dilution ratios at low load. (a) SS + ED, (b) ED1 + ED2 and PRD + ED, (c) PRD.

FIG. 4 Number size distributions measured with DMA + CNC for different dilution systems and dilution ratios at high load.

FIG. 5 Count median diameters (CMD) together with geometric standard deviations (σ_g) and total number concentrations (N_tot) as a function of dilution ratio (DR) for SS + ED (DR(ED) = 11.7, constant) and PRD dilution systems.

FIG. 6 TEM micrographs of individual exhaust gas particles from a turbo-charged off-road diesel engine sampled at the location presented in Figure 1a. (a) An overview of the typical particles found on the sample presenting particles of about 40 nm in size, (b) a close-up of a typical nucleated primary particle of 5–7 nm in size.

TABLE 3 Estimated residence times in the different diluters

Dilution	Residence time [ms]	T [°C] primary secondary
ED	870 ^1	182
		32, 25
SS	350 ^2	52
PRD	300–500 ^3	25

Backman , U. , Jokiniemi , J. K. , Auvinen , A. and Lehtinen , K. E. J. 2002 . The Effect of Boundary Conditions on Gas-Phase Synthesised Silver Nanoparticles . J. Nanoparticle Research , 4 : 325 – 335 .

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