Investigations on thermal characteristics in a double pipe fitted with circular finned and frequently spaced helical twi
- PDF / 2,189,561 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 79 Downloads / 166 Views
ORIGINAL ARTICLE
Investigations on thermal characteristics in a double pipe fitted with circular finned and frequently spaced helical twisted inserts and Graphene oxide nanofluid H. M. Shankara Murthy 1 & Ramakrishna N. Hegde 2 Received: 27 May 2019 / Accepted: 29 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this experimental study, the influence of combined passive technique on heat transfer, friction factor, and thermal performance factor are investigated in a double pipe heat exchanger fitted with different turbulators and GO-Water nanofluid. Experiments were conducted for a fixed flow rate of (Re = 2500) in the inner tube (hot fluid); for varying flow rates (500 ≤ Re ≤ 5000) and volume concentrations (0.05%–0.15%) of GO-Water nanofluid in the outer tube (cold fluid), under uniform heat flux condition, using i) circular finned twisted tape inserts with TR = 20, 13.3 and 9.8 ii) frequently spaced helically twisted inserts with the number of helices = 5, 7, 9). The experimental results showed that the Nusselt number and Thermal Performance Factor (TPF) were increased with decreased twist ratio and increased helices and volume concentration of nanofluid. The enhancement of heat transfer was 21.35% and 22.21%, respectively, whereas the enhancement in the Thermal Performance Factor (TPF) was 7.16% and 8.06%, respectively, for the above two test conditions. The augmentation was maximum for configurations corresponding to the circular finned twisted tape insert with TR = 9.8 and frequently spaced helical screw-tape with 9 helices in 0.15% volume concentrations of GO-water nanofluid as compared to other combinations, with a slight penalty in pressure drop. Nomenclature V Velocity, m s−1 d Diameter, m L Length, m T Temperature, OC Cp Specific Heat, J.kg−1 K−1 Q Heat transfer K Thermal conductivity, W.m−1 K−1 h Heat transfer coefficient, W.m−2 K−1 Re Reynolds Number Nu Nusselt Number Pr Prandtl Number f Friction factor ΔP Pressure Drop, bar * Ramakrishna N. Hegde [email protected] H. M. Shankara Murthy [email protected] 1
Department of Mechanical Engineering, Sahyadri College of Engineering & Management, Adyar, Mangaluru, Karnataka, India
2
Department of Automobile Engineering, Srinivas Institute of Technology, Valachil, Farangipete Post, Mangaluru, Karnataka, India
D Tape width, m H Pitch length of tape, m U Uncertainty X Sample mean n Sample size Greek/Roman/Latin letters ρ Density, kg m−3 μ Dynamic Viscosity, kg.m s−1 ϕ Volume concentration σ Standard Deviation Subscripts nf Nanofluid bf Base fluid f Fluid P Particle W Water m Mass h Hot fluid c Cold fluid hi Hot fluid inlet ho Hot fluid outlet ci Cold fluid inlet co Cold fluid outlet Abbreviations DPHE Double Pipe Heat Exchanger
Heat Mass Transfer
TR LMTD TPF
Twist Ratio Logarithmic Mean Temperature Difference Thermal Performance Factor
1 Introduction Heat exchangers are an essential part of any industrial setups, may it be in power plants, refineries, chemical processes, heating, and cooling systems, or micro-sized a
Data Loading...
