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ABSTRACT
In this study an experimental investigation has been carried out to analyze the laminar forced convection of Al2O3/water and multiwall carbon nanotubes (MWCNT)/water nanofluids through uniformly heated horizontal circular pipe with helical twisted tape inserts. Tests were conducted for varied range of nanoparticle volume concentration (0.15%, 0.45%, 0.60%, and 1%) and helical tape inserts of twist ratios of 1.5, 2.5, and 3. The heat transfer enhancement and the increase of friction factor of nanofluids with helical inserts are compared with that of pure water results with plain tube without inserts. The Nusselt number is found to increase with the increase in Peclet number and nanofluid concentration. The MWCNT/water nanofluids with helical screw tape inserts exhibits higher thermal performance compared to Al2O3/water nanofluid. The maximum thermal performance factor was found to be 1.79 and 1.99 for Al2O3/water and MWCNT/water nanofluids with helical twisted tape inserts, respectively. The pressure drop for Al2O3 nanofluid is found to be higher compared to the MWCNT nanofluid for all the twist ratio of helical screw tape inserts.
Nomenclature
| A | = | Wetted area of the test section, m2 |
| CP | = | Specific heat, J/kg K |
| l | = | Length of the insert, m |
| d | = | Diameter of the twisted tape insert (), m |
| D | = | Diameter of the test section diameter, m |
| f | = | Friction factor, dimensionless |
| h | = | Convective heat transfer coefficient, W/m2 0C |
| HI | = | Helical screw tape inserts |
| I | = | Current, A |
| k | = | Thermal conductivity (water, nanofluid), W/m K |
| L | = | Test section length, m |
| = | Mass flow rate, kg/s | |
| Nu | = | Nusselt number (=hD/k), dimensionless |
| P | = | Pitch of twisted tape insert (), m |
| Pe | = | Peclet number (=ρCpuD/k), dimensionless |
| Pr | = | Prandtl number (= μCp/k), dimensionless |
| Q1 | = | Energy supplied, W |
| Q2 | = | Energy absorbed by water, W |
| = | Reynolds number, (= ρuD/μ), dimensionless | |
| T | = | Temperature, 0C |
| = | Average temperature of the wall, 0C | |
| = | Bulk temperature of fluid, 0C | |
| TR | = | Twist ratio |
| u | = | Fluid velocity, m/s |
| V | = | Voltage, V |
| W | = | Weight of nanoparticle, kg |
| x | = | Axial distance from inlet, mm |
| Greek symbols | ||
| φ | = | Volume concentration, % |
| Δp | = | Pressure drop, N/m2 |
| μ | = | Dynamic viscosity, kg/m2-s |
| ρ | = | Density, kg/m3 |
| θe | = | Contact angle, rad |
| η | = | Thermal performance factor, dimensionless |
| Subscripts | ||
| bf | = | Basefluid |
| in | = |
|
| out | = | Outlet |
| pt | = | Plain tube |
| s | = | Nanoparticles |
| w | = | Wall |
Additional information
Notes on contributors
Sandesh S. Chougule
Sandesh S. Chougule received his Master's (2012) and PhD (2015) degrees from Government College of Engineering Karad and Indian Institute of Technology Indore, respectively. He is serving as an Assistant Professor in Mechanical-Mechatronics Engineering at the LNM Institute of Information Technology, Jaipur, India. Prior to his arrival at LNMIIT Jaipur, he served as an assistant professor in the Department of Mechanical Engineering at BITS Pilani, K K Birla Goa Campus from 2015 to 2016. He has published 12 articles in reputed international journals. He has presented and published 21 research papers in reputed ASME conferences (in India and abroad). His research areas are nanofluids, enhanced heat transfer, jet impingement, heat pipes and solar energy.
Vishal V. Nirgude
Vishal V. Nirgude is a PhD student at Indian Institute of Technology (Department of Mechanical Engineering), Indore, India, working under the supervision of Dr. S. K. Sahu. He received his M. Des degree in Mechanical Systems Design in 2014 from Indian Institute of Information Technology Design & Manufacturing Kancheepuram, Chennai, India.
Santosh K. Sahu
Santosh Kumar Sahu is serving as Associate Professor in the Discipline of Mechanical Engineering at Indian Institute of Technology Indore. He has received his Master's (2004) and PhD (2009) degrees from Indian Institute of Technology Bombay and Indian Institute of Technology Kharagpur India, respectively. His research interests include rewetting of hot surfaces, quenching of hot stationary and moving surfaces, heat transfer enhancement with nanofluids, heat transfer behavior of gaseous flows in micro devices, pool boiling heat transfer, impinging jets, heat exchanging equipments, flow through corrugates tubes. He has published 31 international indexed journal papers and 35 articles in international conference proceedings, besides contributing 3 articles in the edited book published by Springer. He has received the prestigious IUSSTF Research Fellowship by Indo-US Science and Technology Forum for Engineering Sciences in 2011. Under the Indo-US Research Fellowship programme, he has visited Purdue University, West Lafayette, Indiana, USA during September 2011 to January 2012. He is serving as the member of Editorial Board of ISRN Mechanical Engineering since 2010.