A Two-Dimensional Laminar Flow Model for Thermodenuders Applied to Vapor Pressure Measurements

Figures & data

TABLE 1 Properties of the dicarboxylic acids modeled in this study

	Mv	ρ v	γ v	σ v	ϵ v /kB
Compound	(g/mol)	(g/cm^3)	(N/m)	(Å)	(K)
Butanedioic acid	118.08	1.566^a	0.125^b	5.69^b	885.41^b
Hexanedioic acid	146.14	1.362^a	0.06^b	6.30^b	818.21^b
^aThalladi et al. (2000).
^bBilde et al. (2003).

FIG. 1 Comparison of temperatures and vapor concentrations predicted by the 1-D plug-flow and the 2-D laminar-flow models. T_b and c_b are the bulk temperature and vapor concentration obtained by the 1-D model. T_avg and c_avg are the cup-average temperature and vapor concentration obtained by the 2-D model. T_w is wall temperature. c_sw and c_sb are the saturation vapor concentrations at T_w and T_b . (Color figure available online.)

FIG. 2 Comparison of the measured and model-predicted MFR: (a) model differences, for butanedioic acid; (b) effect of initial aerosol concentration (C_OA), for hexanedioic acid. (Color figure available online.)

FIG. 3 Sensitivity test results for hexanedioic acid for (a) evaporation coefficient; (b) saturation vapor pressure at 25°C; and (c) enthalpy of vaporization. (Color figure available online.)

TABLE 2 Summary of the values for the saturation vapor pressure at 25°C (p⁰) and the enthalpy of vaporization (ΔH_v ) reported by different investigators

				Hexanedioic acid
		Butanedioic acid
Figure 6					ΔHv
Label*	Reference	p ^0 (10^−4 Pa)	ΔHv (kJ/mol)	p ^0 (10^−5 Pa)	(kJ/mol)	Method
a	Davies and Thomas (1960)	0.423	117.4	0.842	129.4	Effusion
b	Weast (1982)	–	–	0.8	130	Effusion
c	Tao and McMurry (1989)	–	–	1.445	117.54	Kinetic
d	Chattopadhyay et al. (2001)	–	–	1.7	140	Kinetic
e	Bilde et al. (2003)	0.459	137.8	1.413	154.4	Kinetic
f	Chattopadhyay and Ziemann (2005)	1.37	119.5	3.02	146.2	Kinetic
g	Cappa et al. (2007)	0.32	128	0.26	145	Kinetic
h	Saleh et al. (2009)	3.7	88	3.4	135	Integrated volume
*Codes used in Figure 6 to identify each measurement point.

FIG. 4 Adjustment of the evaporation coefficient (γ_e) to fit the measured MFRs: (a) butanedioic acid; (b) hexanedioic acid. Also shown is the influence of variability/uncertainty in the initial aerosol concentration (C_OA) for the central values of γ_e. (Color figure available online.)

FIG. 5 Adjustment of the reference saturation pressure and the enthalpy of vaporization to fit the measured MFRs: (a) butanedioic acid; (b) hexanedioic acid. (Color figure available online.)

FIG. 6 Contour plots for evaporation coefficient (colored) and deviation percent (contours) as functions of the reference saturation vapor pressure and the enthalpy of vaporization: (a) butanedioic acid; (b) hexanedioic acid. Literature-reported values listed in Table 2 and the best-fit values shown in Figure 5 are also shown.

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