Table 2 Summary of forced convection experimental studies on nanofluids under constant heat flux boundary conditions

He et al. (2007)

TiO₂/water

Ultrasonication

95,145 and 210

1.0, 2.5 and 4.9 (wt.%)

Laminar and Turbulent (800–6500)

Increasing particle concentration and decreasing particle (agglomerate) size

Kayhani et al. (2012)

TiO₂/water

Two step

15

0.1, 0.5, 1, 1.5 and 2

Turbulent (7000–15000)

Particle volume concentration

Rayatzadeh et al. (2013)

TiO₂/water

Two step

30

0- 0.25

Laminar (800–2000)

Dispersion of suspended nanoparticles and sonication

Wen and Ding (2004)

γ-Al₂O₃/water

Ultrasonic bath

26-56

0- 4 (wt. %)

Laminar/entrance region (600–2200)

Non-uniform distribution of thermal conductivity due to particle migration effect and thermal boundary layer thickness reduced with effect of viscosity field

Anoop et al. (2009)

Al₂O₃/water

Laser evaporated physical

45 and 150

1, 2, 4 and 6 (wt. %)

Laminar/developing flow (500–2500)

Thermal dispersion and particle migration effects

Hwang et al. (2009)

Al₂O₃/Water

Two step method (ultrasonication)

30

0.01-0.3

Fully developed laminar flow (500–800)

Due to particle migration induced by Brownian diffusion there was flattening of velocity profile and thermopherisis

Chandrasekar et al. (2010)

Al₂O₃/Water

Microwave assisted chemical precipitation method

43

0.1

Fully- developed Laminar flow (600–2400)

Flattens the temperature distribution due to the effects of dispersion or back-mixing which is attributed by wire coil insert and create the temperature gradient steeper between the fluid and wall

Mansour et al. (. 2011)

Al₂O₃/water

-

36

0-4

Laminar mixed convection flow (350–900)

Particle volume concentration and inclination of tube

Yu et al. (2012)

Al₂O₃-polyalphaolefin (PAO)

Ultra- sonication (spherical, nano-rods)

60 for spherical; d = 7, l = 85 for nano-rods

0.65

Laminar (100–500)

Particle volume concentration, other parameters such as dispersion state, aspect ratio and aggregation of nanoparticles as well as the shear field

Sahin et al. (2013)

Al₂O₃/water

Two step

-

0.5, 1, 2 and 4

Turbulent (4000–20,000)

Particle volume concentration and Reynolds number

Esmaeilzadeh et al. (2013)

γ-Al₂O₃/water

Ultrasonication

15

0.5, 1

Laminar (400–2000)

Particle volume concentration

Suresh et al. (2012)

CuO/ Water

Sol–gel method

15.7

0.1, 0.2 and 0.3

Turbulent (2500–6000)

Increasing volume concentration in plain tube, Reynolds number and dimpledtube in geometry

Razi et al. (2011)

CuO/oil

Chemical Analysis

50

0.2, 0.5, 1 and 2 (wt. %)

Laminar (10–100)

Flattening the tube profile

Saeedinia et al. (2012)

CuO/oil

Chemical Analysis

50

0.07 -0.3

Laminar (15–110)

Wire coil insert

Hashemi and Akhavan-Behabadi (2012)

CuO/oil

Ultrasonic processor

50

0.5,1 and 2 (wt. %)

Laminar (100–2000)

Helical tube curvature

Selvakumar and Suresh (2012)

CuO/water

Ultrasonication

27-37

0.1 and 0.2

Turbulent ( 2985–9360)

Increment in the volume flow rate and nanoparticle volume fraction

Yu et al. (2013)

Copper-in-Therminol 59

Sonication

50 to 100

0.50, 0.75 and 2.00

Turbulent (3000–8000)

Base fluid used as high temperature heat transfer fluid

Sundar et al. (2012)

Fe₃O₄/Water

Purchased from Sigma Aldrich Chemicals Ltd., USA

36

0-0.6

Turbulent (3000–22,000)

Use of twisted tape insert of twist ratio H/D = 5

Ding et al. (2006)

^*MWCNT/water

Ultrasonication and high shear homogenization

-

0.5 (wt. %)

Laminar (800–1200)

Particle re-arrangement, due to the presence of nanoparticles there was reduction of thermal boundary layer, shear induced thermal conduction enhancement

Chen et al. (2008)

Titnate nanotube/ water

Shear homogenizing

^*d = 10 l = 100

0.5, 1.0 and 2.5 (wt. %)

Laminar (1100–2300)

Particle re-arrangement under shear, enhanced wettability and particle shape effect and aggregation (structuring)

Garg et al. (2009)

*MWCNT/water,

Ultrasonication/ Power Law viscosity model

^*d = 10–20 l = 0.5- 40 μm

1

Laminar (600–1200)

Increase in axial distance

Amrollahi et al. (2010)

FMWNT/water

Ultrasonication

150–200

0, 0.1, 0.12, 0.2 and 0.25 (wt. %)

Laminar and Turbulent (1500–5000)

Effective parameters includingmass fraction, Reynolds number, and temperature, altogether in entrance region

Liu et al. (2010)

^*CNT/CTAC

Ultrasonic bath

^*d = 10-20 l = 1–2 μm

0.5, 1.0, 2.0 and 4.0 (wt. %)

Turbulent (10⁴ to 5 \( \times \)10⁴)

A new kind of aqueous drag reducing base fluid

Behbadi et al. (2012)

^*MWCNT/heat transfer oil

Ultrasonic processor

-

0.1, 0.2 and 0.4 (wt. %)

Laminar (100–1800)

Diffusion of particle in base fluid and helical tube profile

Wang et al. (2013)

^*MWCNT/De-ionized water

Binary mixing

^*d=20-30 l=5-30 μm

0.0 and 0.24

Laminar (20 to 250)

Enhanced thermal conductivity and nature of nanoparticle

Azmi et al. (2013)

SiO₂/water

Mechanical Homogenisation

22

0- 4

Turbulent (5000–27,000)

Increment in particle volume concentration

Kim et al. (2009)

Alumina/water amorphous carbonic nanoparticles/ water

Two step and one step

20-50

0-3 0–3.5

Laminar (800–2400) and Turbulent (3000–6500)

Disturbances of thermal boundary layers

Rea et al. (2009)

Alumina/water Zirconia/water

Purchased Nyacol_Nano Technologes Inc.

50

0- 6 0-3

Laminar- entrance and fully-developed region (432–1888); (333–356)

Due to various mixture properties of nanofluid

Vajjha et al. (2010)

^*Al₂O₃/EG-water (60:40) CuO/EG-water(60:40) SiO₂/EG-water (60:40)

Ultrasonication

45 29 20, 50 and100

0-0.1 0–0.006 0–0.1

Fully developed turbulent (2200–16000)

Particle volume concentration

Suresh et al. (2011)

Al₂O₃–Cu/water hybrid nanofluid

Two Step method

15

0.1

Fully developed laminar (700–2300)

Hybrid nanofluid has higher friction factor than Al₂O₃/water nanofluid