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Research Papers

# Effect of γ-Al2O3/Water Nanofluid on Heat Transfer and Pressure Drop Characteristics of Shell and Coil Heat Exchanger With Different Coil Curvatures

[+] Author and Article Information
M. R. Salem

Mechanical Engineering Department,
Faculty of Engineering at Shoubra,
Benha University,
108 Shoubra Street, Cairo 11629, Egypt
e-mails: me_mohamedreda@yahoo.com;
mohamed.abelhamid@feng.bu.edu.eg

R. K. Ali

Mechanical Engineering Department,
Faculty of Engineering at Shoubra,
Benha University,
108 Shoubra Street, Cairo 11629, Egypt
e-mail: ragabkhalil1971@gmail.com

R. Y. Sakr

Mechanical Engineering Department,
Faculty of Engineering at Shoubra,
Benha University,
108 Shoubra Street, Cairo 11629, Egypt
e-mail: rsakr85@yahoo.com

K. M. Elshazly

Mechanical Engineering Department,
Faculty of Engineering at Shoubra,
Benha University,
108 Shoubra Street, Cairo 11629, Egypt
e-mail: drkaramelshazly@yahoo.com

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received May 7, 2014; final manuscript received March 31, 2015; published online June 9, 2015. Assoc. Editor: Mehmet Arik.

J. Thermal Sci. Eng. Appl 7(4), 041002 (Jun 09, 2015) (9 pages) Paper No: TSEA-14-1117; doi: 10.1115/1.4030635 History: Received May 07, 2014

## Abstract

This study presents an experimental investigation of the characteristics of convective heat transfer in horizontal shell and coil heat exchangers in addition to the friction factor for fully developed flow through their helically coiled tube (HCT). Five heat exchangers of counterflow configuration were constructed with different HCT-curvature ratios ($δ$) and tested at different mass flow rates and inlet temperatures of γ-Al2O3/water nanofluid in the HCT. The tests were performed for γ-Al2O3 with average size of 40 nm and particles volume concentration ($ϕ$) from 0% to 2% for $0.0392≤δ≤0.1194$. Totally, 750 test runs were performed from which the HCT-average Nusselt number ($Nu¯t$) and fanning friction factor ($fc$) were calculated. Results illustrated that $Nu¯t$ and $fc$ of nanofluids are higher than those of the pure water at same flow condition, and this increase goes up with the increase in $ϕ$. When $ϕ$ increases from 0% to 2%, the average increase in $Nu¯t$ is of 59.4–81% at lower and higher HCT-Reynolds number, respectively, and the average increase in $fc$ is of 25.7% and 27.4% at lower and higher HCT-Reynolds number, respectively, when $ϕ$ increases from 0% to 2% for $δ=0.1194$. In addition, results showed that $Nu¯t$ and $fc$ increase by increasing coil curvature ratio. When $δ$ increases from 0.0392 to 0.1194 for $ϕ=2%$, the average increase in $Nu¯t$ is of 130.2% and 87.2% at lower and higher HCT-Reynolds number, respectively, and a significant increase of 18.2–7.5% is obtained in the HCT-fanning friction factor at lower and higher HCT-Reynolds number, respectively. Correlations for $Nu¯t$ and $fc$ as a function of the investigated parameters are obtained.

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## Figures

Fig. 1

Schematic diagram of the experimental apparatus

Fig. 2

A photograph of the experimental apparatus

Fig. 3

(a) A photograph and (b) schematic diagram of the test section

Fig. 4

Photographs of the observed nanoparticles settlement (ϕ=2%)

Fig. 5

Validation of the experimental data for HCT (λ=0.0895)

Fig. 6

Variation of HCT-average Nusselt number with HCT-Reynolds number at different nanoparticles concentrations (Tt,i=55 °C, δ = 0.0591)

Fig. 7

Variation of HCT-average Nusselt number with HCT-Reynolds number at different HCT-curvature ratios (ϕ=1%,Tt,i=55 °C)

Fig. 8

Variation of HCT-average Nusselt number with HCT-Reynolds number at different HCT-inlet temperatures (ϕ=1%): (a) δ=0.0472 and (b) δ=0.1194

Fig. 9

Variation of HCT-fanning friction factor with HCT-Reynolds number at different nanoparticles concentrations (Tt,i=55 °C): (a) δ=0.1194 and (b) δ=0.0392

Fig. 10

Variation of HCT-fanning friction factor with HCT-Reynolds number at different HCT-curvature ratios (ϕ=1%,Tt,i=55 °C)

Fig. 11

Variation of HCT-fanning friction factor with HCT-Reynolds number at different HCT-inlet temperatures (ϕ=1%,δ=0.0591)

Fig. 12

Variation of the average TPI with HCT-curvature ratio at different nanoparticles concentrations: (a) Tt,i=65 °C, (b) Tt,i=55 °C, and (c) Tt,i=45 °C

Fig. 13

Variation of the average TPI with HCT-volume flow rate at different nanoparticles concentrations

Fig. 14

Comparison of experimental values for HCT-average Nusselt number with that correlated by Eq. (23)

Fig. 15

Comparison of experimental values for HCT-fanning friction factor with that correlated by Eq. (24)

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