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

Abstract

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 (∼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/m2.K for the working temperatures of 20 and 30 °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.