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PCRF and PN accuracy

PCRF and PN accuracy. Comparison of R83 and JAMA proposal. PCRF principle (big size) – R83 (1.3/1.2/1.0). For the worst case (PCRF 30 =1.3xPCRF 100 , PCRF 50 =1.2xPCRF 100 ) the PN emissions measured by the CPC are corrected with a factor of 1.17

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PCRF and PN accuracy

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  1. PCRF and PN accuracy Comparison of R83 and JAMA proposal

  2. PCRF principle (big size) – R83 (1.3/1.2/1.0) For the worst case (PCRF30=1.3xPCRF100, PCRF50=1.2xPCRF100) the PN emissions measured by the CPC are corrected with a factor of 1.17 This can lead to overestimation of the emissions when the median of the exhaust aerosol is close to 100 nm

  3. PCRF principle (small size) – R83 (1.3/1.2/1.0) For the worst case (PCRF30=1.3xPCRF100, PCRF50=1.2xPCRF100) the PN emissions measured by the CPC are corrected with a factor of 1.17 This can lead to underestimation of the emissions when the median of the exhaust aerosol is close to 30 nm

  4. PCRF principle (big size) – JAMA (1.2/1.0/1.0) For the worst case (PCRF30=1.2xPCRF100, PCRF50=1.0xPCRF100) the PN emissions measured by the CPC are corrected with a factor of 1.07 This can lead to overestimation of the emissions when the median of the exhaust aerosol is close to 100 nm

  5. PCRF principle (small size) – JAMA (1.2/1.0/1.0) For the worst case (PCRF30=1.2xPCRF100, PCRF50=1.0xPCRF100) the PN emissions measured by the CPC are corrected with a factor of 1.07 This can lead to underestimation of the emissions when the median of the exhaust aerosol is close to 30 nm

  6. PCRF ratios Minimum acceptable PCRF ratios are 1.2 / 1.1 / 1.0

  7. Errors in final PN result

  8. Conclusions • The JAMA proposal corrects the PN results only 2-4% • even for extreme cases of size distributions entering the VPR • (maximum errors are 17% R83 and 7% JAMA, thus 10% improvement, • e.g. in case of monodisperse particles of 100 nm entering the VPR) • Note that depending on the size distribution the corrections might not improve the results (i.e. not in the right direction) • - The improvement has to do with the ratios of the PCRFs • and not the absolute value of the PCRF100 • - Thus the JAMA proposal would be possible even with 100 nm penetration • of 70% • - The 1.2 / 1.0 / 1.0 ratios are experimentally not realistic • The 1.2 / 1.1 / 1.0 ratios are more realistic (but strict) • Based on these ratios the correction is 2-3% even in extreme cases • The minor importance of the 30 nm ratio has to do with the CE of the CPC • (only 70% of the particles at this size are measured) • Thus the 1.3 and 1.2 ratios should remain the same, • and the 70% penetration is acceptable

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