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

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).