Enhancement of the air quality and heat transfer rate of an air-conditioning system using a hybrid polypropylene nanofilter

The design of a new air filter for air-conditioning systems needs to properly manage antimicrobial activity and heat transfer performance. In this work, a hybrid nanofilter of polypropylene coated with silver nanoparticles and multiwall carbon nanotubes (Ag-MWCNTs/PP) was prepared using a modified impregnation technique under vacuum. The results demonstrated a high dispersion of AgNPs (similar to 18 nm) and MWCNTs on the polymer fibers. The antimicrobial activity of the nanofilters was evaluated against Salmonella enterica, Pseudomonas aeruginosa, and Staphylococcus aureus bacteria. A dramatic ability to kill all types of bacteria by 100 % was observed after adding 2 mg/mL of Ag-MWCNTs. Moreover, the pressure drop and convective heat transfer across the nanofilter were evaluated by building a special testing apparatus. The pressure drop rose with increases in the air velocity. Additionally, a high heat transfer coefficient with increases in the air velocity was achieved, with values of 52.5 and 47.3 W/m(2).K for the working temperatures of 20 and 30 degrees C, respectively. Also, the thermal conductivity of the nanofilter was enhanced significantly by 36 %, 48 %, and 68 % at additions of 1, 2, and 3 mg/mL, respectively. The prepared nanofilter showed high efficiency, low cost, and applicability for commercial production. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.