Heat transfer and friction factor analysis of MWCNT nanofluids in double helically coiled tube heat exchanger

The convective heat transfer rate and friction factor analysis are determined with the help of a double helically coiled tube heat exchanger by handling multiwall carbon nanotube (MWCNT)/water-based nanofluids as a cooling medium. This experiment was conducted with constant heat flux method and a laminar flow regime in the range of 120-180 L h(-1). The 0.2-0.6% volume concentration of MWCNT/water-based nanofluids was prepared by using two-step methods. It is conceived that the MWCNT/water-based nanofluids had produced a higher convective heat transfer compared with water. It is also perceived that heat transfer increases with an increasing volume concentration of MWCNT/water-based nanofluids. Finally, the highest convective heat transfer 35% was recorded at a 0.6% volume concentration of MWCNT/water-based nanofluids at 140 L h(-1) flow rate and at 1400 Dean number. It is drawn that the friction factor using MWCNT nanofluids is 40% greater than water with Dean number range 1400-2400.