Carbon nanotubes/paraffin wax nanocomposite for improving the performance of a solar air heating system. (1st June 2021)

• Record Type: Journal Article
• Authors: Habib, Nasser A.; Ali, Ali J.; Chaichan, Miqdam T.; Kareem, Mays
• Is Part Of: Thermal science and engineering progress. Volume 23(2021)
• Publication Date: 2021-06-01
• Subjects: Solar air heater -- SWCNT/paraffin wax nanocomposite -- PCM -- Natural and forced convection; Heat engineering -- Periodicals; Heat engineering; Thermodynamics; Periodicals; 621.402
• DOI: 10.1016/j.tsep.2021.100877
• Languages: English
• ISSNs: 2451-9049

Abstract

Highlights: Paraffin and many SWCNT/paraffin fractions composite materials were prepared. 3 wt% of SWCNT was added to paraffin used in the solar air heater. CNTs improved thermal conductivity of composite materials by 12%. CNTs raised the thermal energy storage of composite material by 21.2%. CNTs reduced the paraffin's melting point by 4.5 °C. CNTs reduced the paraffin's solidification point by 9 °C. Abstract: The study aims to demonstrate the possibility of taking advantage of the high solar radiation in Iraq effectively in heating the air for worming rooms and buildings in winter. The optimal diffusion of solar air heating applications depends mainly on the amount of heat stored and how quickly this heat is transferred to the air. The use of phase change materials to increase thermal storage is one of the best alternatives to date. The disadvantage of these materials is a clear reduction in their thermal conductivity, which impedes the rapid transfer of heat from them to the air. In this study, single wall carbon nanotubes (SWCNT) was added to a local Iraqi made paraffin wax, and the nanocomposite was used in a solar air heater. The SWCNT/paraffin nanocomposite thermophysical properties were examined to show its effect on the solar air heater performance. From the thermophysical properties of the carbon nanotubes added to paraffin in variable mass fractions, 3 wt% was selected. The addition of nanoparticles caused a slight increase in product density and viscosity. The percolation threshold of 3 wt% CNTs increased its thermal conductivity by 12%, reducing the melting and solidification points by 4.5 °C and 9 °C, respectively. The SWCNT/paraffin nanocomposite has improved the stored thermal energy by 20.7% for natural convection, and by 21.2% for forced convection compared to pure paraffin. Results of practical tests confirmed the possibility of using the proposed air heater to work in Iraqi weather conditions.