Extended Verhoff-Banchero acid dew point model

This paper proposes a modification to the Verhoff-Banchero relation describing the acid dew point temperature, based on the evaluation of a generic equation that revealed two major limitations. First, the original relation’s narrow application range was identified through comparison with the H2O-H2SO4 vapour-liquid equilibrium dataset from the literature. Second, testing of the function’s limits showed that the acid dew point temperature does not approach the water dew point temperature as the sulfuric acid concentration approaches zero. To address these limitations, the Verhoff-Banchero relation is extended into a bivariate quadratic function. Regression parameters, along with their estimation errors, are derived using the aforementioned dataset and the least squares method. Statistical test (p-value < 0.01) confirmed the significance of the introduced quadratic terms. The maximum estimation error for the modified relation is found to be ±10°C across a broad application range, with water partial pressures from 1013.25 Pa to 101325 Pa and sulfuric acid liquid mass fractions ranging from 0.1 to 0.98. Additionally, two semi-empirical relations are proposed, incorporating liquid-phase composition as an independent variable. The proposed extended Verhoff-Banchero model was evaluated using an experimental dataset for exhaust gas. Data points fall within an acceptable deviation range, with exceptions from two specific datasets. One of the observed deviations is explained by the partial derivative of the acid dew point temperature with respect to sulfuric acid partial pressure. The limitations of the proposed relations are discussed. Finally, the conclusions with potential future research directions in modelling the H2O-H2SO4 system in exhaust gas are outlined.