International Communications in Heat and Mass Transfer
Experimental investigation of turbulent heat transfer and flow characteristics of SiO2/water nanofluid within helically corrugated tubes☆
Introduction
Heat transfer enhancing techniques are used in heat exchanger to reduce and promote the size and performance, respectively. Generally, there are two group techniques for augmenting the heat transfer: passive and active techniques. One of the best passive techniques is based on introducing surface roughness that disturbs the boundary layer and promoting the turbulence near surfaces. Several roughened tube such as finned tubes, helical tubes, fluted tubes and elliptical axis tubes were investigated by many researchers [1], [2], [3], [4], [5], [6], [7], [8]. Among them, the helically corrugated geometries have been most considered. Helically corrugation creates the chaotic flow mixing and reducing the thickness of thermal boundary layer that increases the heat transfer.
Vicente et al. [9], [10] performed several experiments for laminar, transient and turbulent flows in the HCT with different corrugation heights and pitches. They measured the isothermal friction factor and Nusselt number. Results show that heat transfer does not sensitively change in laminar flow while it intensifies in the turbulent flow. They represented this phenomenon that helical corrugation as roughened surfaces increase flow turbulence and mixes in the near‐wall flow, which is effective in turbulent flow but not in laminar flow. Naphon et al. [11] conducted experimental study on the heat transfer and friction factor in horizontal double pipes using helical ribbed tube. They investigated the effect of relative height and pitch of corrugations on the heat transfer and pressure drop. They used helical ribbed tube with diameter lesser than 10 mm against of other researchers. In agreement with others, they found that the height of corrugation has more significant effect in respect to corrugation pitch on heat transfer and pressure drop. Laohalertdecha and Wongwises [12] studied the effect of corrugation pitch on the condensation heat transfer coefficient and pressure drop of R-134a inside a horizontal HCT. Result indicates that the corrugation pitch has significant effect on heat transfer which increases by increasing the pitch to diameter ratio. Petkhool et al. [13] investigated the turbulent heat transfer enhancement in a concentric tube heat exchanger with helically corrugated tube as inner tube. They studied the effect of three different piths to diameter ratio and three different heights to diameter ratio on heat transfer and isothermal friction augmentation. They proposed a correlation base on their results for Reynolds number ranging from 5500 to 60,000. Another passive method as alternative heat transfer enhancing method is related to adding the nano-particles to based fluid. It increases the heat transfer through with enhancing the thermal conductivity of nanofluid. This method is vastly studied experimentally and numerically by many researchers in various geometries, especially in the heat exchanger because of its extensive application in engineering industries.
Recently, many researchers focused on using the two heat transfer enhancing techniques simultaneously, for example using coil insert and twist tape with nano-particles in circular tube [14], [15]. Wongcharee and Eiamsa-ard [16] investigated experimentally the enhancement of heat transfer using CuO/water nanofluid and twisted tape with alternate axis. They performed experiments for laminar regime in Reynolds number ranging from 830 to 1990 and concentration of nano-particle ranging from 0.3% to 0.7% by volume. Results indicate that by employing the 0.7% volume fraction of nano-particle and twist tape simultaneously promotes the thermal performance by factor of 5.53 for Reynolds number of 1990. Suresh et al. [17] conducted an experimental study on heat transfer and isothermal friction characteristics of CuO/water nanofluid with low concentration in dimpled tube. They performed a comparison of heat transfer between plain tube/water and dimpled tube/nanofluid indicating enhancing up to 27% for the second case. Wongcharee and Eiamsa-ard [18] investigated the effect of CuO nano-particles on heat transfer from corrugated tube equipped with twist tape.
Present experiment deals with the enhancement of the heat transfer thorough with helically corrugation and adding the nano-particles to the base fluid. The effect of different volume concentrations of nano-particles on heat transfer from HCT with various heights and pitches of corrugation are discussed in following section.
Section snippets
Experimental apparatus
The schematics diagram of the experimental apparatus is shown in Fig. 1. the test loop consist of cold and hot water pump, hot water tank, nanofluid tank as cold fluid tank, cooling unit and concentric tubes as test section. The length of test section was 220 cm copper tube with inner diameter of 8.1 mm and steel tube with a diameter of 150 mm was selected as inner and outer tubes of test section. The outer surface of test section was isolated thermally from surrounding with thick layer of glass
Results and discussions
In this section, firstly the obtained experimental results for plain tube and HCT are validated and compared with those of Naphon et al. [11] work. After that, the effect of nano-particles on heat transfer and friction factor from HCT with different heights and pitches of corrugation are investigated.
Conclusion
In present work, an experimental study performed to explore the effect of SiO2 nano-particles in helically corrugated tubes. Experimental data for pure fluid was compared with Naphon et al.'s [11] work. Increasing the corrugated height and lowering the corrugated pitch enhance the heat transfer. Also, results reveal that adding the specified amount of nano-particles to pure fluid can enhance the heat transfer with a little pressure drop penalty. Increasing the corrugated height and lowering the
References (24)
- et al.
Forced convection heat transfer in helically rib-roughened tubes
International Journal of Heat and Mass Transfer
(1980) - et al.
Investigation of heat transfer and pressure drop characteristics of flow through spirally fluted tubes
Experimental Thermal and Fluid Science
(1992) - et al.
Heat transfer and pressure drop for low Reynolds turbulent flow in helically dimpled tubes
International Journal of Heat and Mass Transfer
(2002) - et al.
Development and verification of general correlations for heat transfer and pressure drop in single-phase turbulent flow in enhanced tubes
Experimental Thermal and Fluid Science
(1996) - et al.
Convective heat transfer to temperature dependent property fluids in the entry region of corrugated tubes
International Journal of Heat and Mass Transfer
(2002) - et al.
Heat transfer enhancement in corrugated tube
International Communications in Heat and Mass Transfer
(2002) - et al.
Pressure drop, heat transfer and performance of single-phase turbulent flow in spirally corrugated tubes
Experimental Thermal and Fluid Science
(2001) - et al.
Mixed convection heat transfer and isothermal pressure drop in corrugated tubes for laminar and transition flow
International Communications in Heat and Mass Transfer
(2004) - et al.
Experimental investigation on heat transfer and frictional characteristics of spirally corrugated tubes in turbulent flow at different Prandtl numbers
International Journal of Heat and Mass Transfer
(2004) - et al.
Tube side heat transfer coefficient and friction factor characteristics of horizontal tubes with helical rib
Energy Conversion and Management
(2006)
The effects of corrugation pitch on the condensation heat transfer coefficient and pressure drop of R-134a inside horizontal corrugated tube
International Journal of Heat and Mass Transfer
Turbulent heat transfer enhancement in a heat exchanger using helically corrugated tube
International Communications in Heat and Mass Transfer
Cited by (89)
Hydrothermal performance and entropy production rate of rGO-CO<inf>3</inf>O<inf>4</inf>/H<inf>2</inf>O hybrid nanofluid in corrugated-converging pipes
2024, International Journal of Thermal SciencesThe promise of nanofluids: A bibliometric journey through advanced heat transfer fluids in heat exchanger tubes
2024, Advances in Colloid and Interface ScienceNumerical Assessment of Advanced Thermo-Hydrodynamic Characteristics of Nanofluid Inside a Helically Featured Straight Pipe
2024, International Journal of ThermofluidsResearch progress on the influence of nano-additives on phase change materials
2022, Journal of Energy Storage
- ☆
Communicated by W.J. Minkowycz.