# Liquid Nanofilms' Condensation Inside a Heat Exchanger by Mixed Convection
###### Abstract  
Liquid nanofilm is used in industrial applications, such as heat exchangers, water desalination systems, heat pumps, distillation systems, cooling systems, and complex engineering systems. The present work focuses on the numerical investigation of the condensation of falling liquid film containing different types of nanoparticles with a low-volume fraction. The nanofluid film falls inside a heat exchanger by mixed convection. The heat exchanger is composed of two parallel vertical plates. One of the plates is wetted and heated, while the other plate is isothermal and dry. The effect of the dispersion of the \(Cu\) or \(Al\) nanoparticles in the liquid on the heat exchange, mass exchange, and condensation process was analysed. The results showed that the heat transfer was enhanced by the dispersion of the nanoparticles in the water. The copper-water nanofluid presented the highest efficiency compared to the aluminium-water nanofluid and to the basic fluid (pure water) in terms of the heat and mass exchange.  
condensation film; nanofluid; nanoparticles; liquid film; mixed convection +
Footnote †: journal: Applied Sciences  
1
Footnote 1: Mechanical Engineering Department, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah 77207, Saudi Arabia 12 Laboratory of Thermal and Energy Systems Studies, National School of Engineering of Monastir, University of Monastir, Monastir 5000, Tunisia 2  
Footnote 2: Department of Mechanical Engineering, College of Engineering and Islamic Architecture, Umm Al-Qura University, Makkah 77207, Saudi Arabia 1
dispersion of the nanoparticles ameliorated the heat exchange. [PERSON] et al. [10] presented an analysis of water droplets' evaporation containing nanoparticles of titanium dioxide (TiO\({}_{2}\)) under direct current conditions. They showed that the TiO\({}_{2}\) nanofluids' receding contact was continuous and smooth when direct current potential was applied. [PERSON] et al. [11] analysed liquid drop evaporation containing a low concentration of nanoparticles. A comparison between the experimental and theoretical results of the evaporation of nanofluid liquid drops was presented. [PERSON] et al. [12] experimentally analysed liquid film evaporation. They showed that the evaporation was enhanced with an increase in the inlet temperature and inlet air flow rate. [PERSON] [13] numerically investigated falling liquid film evaporation. [PERSON] et al. [14] studied water droplets' evaporation containing a low concentration of Al\({}_{2}\)O\({}_{3}\) nanoparticles. They concluded that the dispersion of Al\({}_{2}\)O\({}_{3}\) nanoparticles to the water droplets with a low concentration did not affect the rate of the evaporation of droplets. [PERSON] et al. [15] presented a finite element analysis for ternary hybrid nanoparticles on thermal enhancement in pseudo-plastic liquid through a porous stretching sheet. They show that the thermal performance was enhanced by the mixing of nanoparticles in the base fluid. [PERSON] et al. [16] presented a finite element analysis for thermal enhancement in a power law hybrid nanofluid. [PERSON] et al. [17] studied the thermal and mass species transportation in tri-hybridised Sisko martial with a heat source over a vertical heated cylinder. [PERSON] et al. [18] presented a numerical study of liquid nanofilms' evaporation inside a heat exchanger by mixed convection.  
This literature review shows that a large number of studies have examined the pure liquid film condensation inside a heat exchanger. To the best of the authors' knowledge, there has been no numerical study dedicated to analysing the liquid nanofilms' condensation inside a heat exchanger by mixed convection. The present paper presents a numerical investigation of the heat and mass transfer during liquid nanofilms' condensation inside a plate heat exchanger. The aim of this study is to reveal the effects of the dispersion of Cu or Al nanoparticles on the mass, heat exchange, and condensation performance.