Contents lists available at ScienceDirect Fuel Processing Technology journal homepage: www.elsevier.com/locate/fuproc Research article Condensational growth assisted Venturi scrubber for soot particles emissions control Francesco Di Natale a , Francesco La Motta a , Claudia Carotenuto b, ⁎ , Marco Tammaro c , Amedeo Lancia a a Department of Chemical Engineering, Materials and Industrial Production, University of Naples “Federico II”, Piazzale V. Tecchio 80, 80125 Naples, Italy b Department of Information and Industrial Engineering, Università della Campania “Luigi Vanvitelli”, via Roma 29, 81031 Aversa, Caserta, Italy c ENEA, Italian National Agency for New Technologies, Energy and the Environment, Research Centre of Portici, Piazzale E. Fermi 1, 80055 Portici, Naples, Italy ARTICLE INFO Keywords: Combustion emissions control Soot particles Condensational growth Venturi scrubber ABSTRACT This paper aims to evaluate how condensational growth may be used to improve the performances of a Venturi scrubber in removing soot particles, which are among the most relevant air pollutants emitted in industrial and power plants exhaust gases. Former studies on this system, called Condensational Growth assisted Venturi scrubbers (CGVS), suggested that the most relevant step to address their efficiency is the assessment of the amount of water that condense on the soot particles, which determines the actual aerosol size distribution entering the Venturi. Unfortunately, a definite physical mathematical model to predict the actual condensational growth of an ensemble of non-spherical particles is not yet available and experimental investigation is better suited to assess this point. This study reports experimental data on the size distribution achieved by exposing model soot particles to a water supersaturated gas for different residence times. The obtained size distributions are used to estimate the efficiency of a Venturi scrubber in removing the water-soot aerosols, allowing a com- parison with the removal of parent soot particles. The experiments were carried out at lab scale by using a laminar-flow growth tube, a simple device to perform a controlled condensational growth. The experiments indicated that, even for a hydrophobic material as soot, condensational growth is effective even at super- saturation levels as low as 1.02. Liquid-solid aerosols from nearly 2 to > 3 times larger than the parent particles are produced with a supersaturation level lower than 1.15. Finally, the analysis of experimental data indicated that the fraction of particles subjected to condensational growth is relevant. Indeed, calling as ψ the fraction of particles that become larger than the 98% percentile of the original particle size distribution, we found that ψ can be as high as 78%. The analysis of data indicated that an appreciable linear correlation exits among ψ and the 95th percentile of the supersaturation level, S 95 , while not being dependent on the exposure time. The experi- mental evidences suggest that the adsorption of water molecules over the soot surface overcome the effects of hydrophobicity and of line tension effects, favouring condensation of water over the soot surface and leading to a higher nucleation rate even at low supersaturation. Application of the Venturi scrubber model to the water-soot aerosol leaving the growth tube indicate that the CGVS may remove particles with an efficiency far higher than that achieved by the stand alone Venturi. For a given Venturi's throat length and velocity and a given liquid-to-gas ratio, the CGVS efficiency depends almost linearly on ψ and, in turns on S 95 . Experimental and model results suggested that the CGVS can be a valuable and effective device to capture soot particles and that condensational growth can be used as a retrofit method for existing units. 1. Introduction Condensational growth, also known as heterogeneous condensation, is a natural phenomenon involved in the formation of clouds [1–4], which is also used in particles diagnostic as a mean to enlarge nano- metric particles and count them optically [5–11]. Condensational growth is also contemplated as a way to generate a liquid-solid aerosol easier to treat by conventional techniques [12–17] rather than the parent solid particles. Recently Niklas et al. [18] pre- sented a new membrane-based process to improve separation efficiency of airborne particles by condensational growth of water vapour, which showed promising experimental results. https://doi.org/10.1016/j.fuproc.2018.01.018 Received 14 November 2017; Received in revised form 22 January 2018; Accepted 23 January 2018 ⁎ Corresponding author. E-mail address: Claudia.carotenuto@unicampania.it (C. Carotenuto). Fuel Processing Technology 175 (2018) 76–89 0378-3820/ © 2018 Elsevier B.V. All rights reserved. T