A lab-scale study on thermal performance enhancement of phase change material containing multi-wall carbon nanotubes for buildings free-cooling. (March 2022)

• Record Type: Journal Article
• Authors: Kazemi, Mahdi; Kianifar, Ali; Niazmand, Hamid
• Is Part Of: Sustainable energy technologies and assessments. Volume 50(2022)
• Publication Date: 2022-03
• Subjects: Encapsulation -- Building -- Heat exchanger -- Melting -- Solidification; Renewable energy sources -- Periodicals; Energy development -- Technological innovations -- Periodicals; Electric power production -- Periodicals; Energy storage -- Periodicals; 333.79
• DOI: 10.1016/j.seta.2021.101813
• Languages: English
• ISSNs: 2213-1388

Abstract

Graphical abstract: Highlights: A heat exchanger containing five similar PCM encapsulations that could be applied in buildings was fabricated. Increasing the air inlet temperature delayed meeting a determined set point temperature for both charging and discharging processes. Nano-PCM had higher solidification and melting rates, compared to that of the pure PCM. An IR camera was employed to investigate the PCM and encapsulation's wall temperature. During cooling period, rising the inlet temperature delays the two-phase time and allows the PCM/nano-PCM to discharge more heat into the air. Abstract: The aim of this research was to experimentally investigate feasibility of using phase change material (PCM) to fabricate an air-PCM heat exchanger to be used in buildings in order to have an effective thermal management as well as enhanced energy performance. RT22HC was selected and encapsulated in the heat exchanger. Due to low thermal conductivity of PCM, multi-wall carbon nanotube (MWCNT) nanoparticles were dispersed into the PCM to compensate this shortage. First, experiments with pure PCM for three successive days had a maximum outlet air temperature of 31.76 °C. As stated, nano-PCM with three different mass fractions (0.1%, 0.2%, and 0.5% wt.) reduced the melting and solidification time compared to the pure PCM. By calculating the absorbed heat by air, 24.1% more heat was charged in encapsulations in the case nano-PCM 0.5% wt. compared to the pure PCM. By investigating the time–temperature behavior of four types of PCMs in solidification, it was observed that rising the nanoparticles concentration decreased the two-phase duration and increased two-phase temperature. Moreover, with the aid of an IR camera, during sensible heating the encapsulation's wall temperature is near the nano-PCM temperature, whereas when latent heating, this difference is much more (@TPCM = 20.00: Tencapsulation = 21.41; (@ TPCM = 21.15: Tencapsulation = 23.17).