Heat transfer of nanofluids in a shell and tube heat exchanger

doi:10.1016/j.ijheatmasstransfer.2009.10.019

International Journal of Heat and Mass Transfer

Volume 53, Issues 1–3, 15 January 2010, Pages 12-17

https://doi.org/10.1016/j.ijheatmasstransfer.2009.10.019 Get rights and content

Abstract

Heat transfer characteristics of γ-Al₂O₃/water and TiO₂/water nanofluids were measured in a shell and tube heat exchanger under turbulent flow condition. The effects of Peclet number, volume concentration of suspended nanoparticles, and particle type on the heat characteristics were investigated. Based on the results, adding of naoparticles to the base fluid causes the significant enhancement of heat transfer characteristics. For both nanofluids, two different optimum nanoparticle concentrations exist. Comparison of the heat transfer behavior of two nanofluids indicates that at a certain Peclet number, heat transfer characteristics of TiO₂/water nanofluid at its optimum nanoparticle concentration are greater than those of γ-Al₂O₃/water nanofluid while γ-Al₂O₃/water nanofluid possesses better heat transfer behavior at higher nanoparticle concentrations.

Introduction

Due to the limitation of fossil fuel in the world, subject of energy consumption optimization in various industrial processes becomes very important. In chemical processes one of the most important devices related to energy and heat transfer is heat exchanger. For decades, efforts have been done to enhance heat transfer, reduce the heat transfer time, minimize size of heat exchangers, and finally increase energy and fuel efficiencies. These efforts include passive and active methods such as creating turbulence, increasing area, etc. Most of them are limited by inherent restriction of thermal conductivity of the conventional fluids (such as water, mineral oil and ethylene glycol). The poor heat transfer properties of the employed fluids in the industries are obstacles for using different types of heat exchangers.

Since solid particles have thermal conductivity higher than that of common fluids, when they are dispersed in the fluids result in higher heat transfer characteristics. There are many types of particles such as metallic, nonmetallic and polymeric. However, due to large size of micro and macro-sized particles, they will face some problems in using of these suspensions, such as clogging of flow channels due to poor suspension stability, erosion of heat transfer device, and increasing in pressure drop.

Modern material technology helps us to produce nanometer-sized particles that their mechanical and thermal properties are different from those of the parent materials. Recently, there has been interest in using nanoparticles to modify heat transfer performance of suspensions. Nanofluids are stable suspension of nanometer-sized particles (smaller than 100 nm in at least one dimension) in conventional heat transfer fluids. Nanofluids are suitable for engineering applications and show several potential advantages such as better stability, dramatically high thermal conductivity and no extra pressure drop compared to other suspensions.

Since thermal conductivity is one of the important parameters for heat transfer enhancement, some studies have been done on thermal conductivity of nanofluids. All experimental results have indicated the enhancement of thermal conductivity by addition of nanoparticles. For example Wang et al. [1], Lee et al. [2], and Das et al. [3] measured the thermal conductivity of nanofluids containing Al₂O₃ and CuO nanoparticles and investigated the effect of the base fluid on the thermal conductivity of the nanofluids. Xie et al. [4], [5] examined the effect of base fluid on thermal conductivity of Al₂O₃ nanofluid. Li and Peterson [6] investigated on the temperature dependency of thermal conductivity enhancement of Al₂O₃/water and CuO/water nanofluids.

There are several published studies on the forced convective heat transfer coefficient of nanofluids and most of them are under the constant heat flux or constant temperature boundary conditions at wall of tubes and channels. In shell and tube heat exchangers the real heat boundary condition is different from the aforementioned boundary conditions and wall temperature and/or heat flux is not constant. The experimental results for forced convection inside a channel show that convective heat transfer coefficient of nanofluids is enhanced compared to base fluid. These studies include investigation on convective heat transfer of γ-Al₂O₃/water and TiO₂/water nanofluids for turbulent flow in a stainless steel tube [7], copper nanoparticles suspended in water for turbulent flow in a brass tube [8], suspensions of γ-Al₂O₃ nanoparticles in water for laminar flow in a copper tube [9], graphite nanoparticles dispersed in two base fluids for laminar flow in a horizontal tube exchanger [10], CuO/water and Al₂O₃/water nanofluids for laminar flow in a copper tube [11], aqueous suspensions of TiO₂ nanoparticles and nanotubes flowing upward through a vertical pipe in both laminar and turbulent flow regimes [12], [13].

The objective of the present study is to investigate on the heat transfer characteristics (such as overall and convective heat transfer coefficients, and Nusselt number) of γ-Al₂O₃/water and TiO₂/water nanofluids for turbulent flow in a horizontal stainless steel shell and tube heat exchanger.

Section snippets

Experimental setup

Fig. 1 shows the flow loop of constructed system. The system mainly includes two flow loops (nanofluids and water flow loops). It contains a stainless steel shell and tube heat exchanger, a heating tank (15 L), a nanofluids cooling system, a nanofluids reservoir tank (5 L), by-pass-line, two pumps in order to provide required flow rates, thermocouples, and two flow meters.

The test section is a shell and tube heat exchanger where nanofluid passes through the 16 tubes with 6.1 mm outside diameter, 1

Data processing

The experimental data were used to calculate overall heat transfer coefficient, convective heat transfer coefficient and Nusselt number of nanofluids with various particle volume concentrations and Peclet numbers. The thermophysical properties were calculated based on mean bulk temperature of nanofluids.

The heat transfer rate of the nanofluid is $Q = \dot{m} C_{p_{nf}} (T_{out} - T_{in})$ where $\dot{m}$ is the mass flow rate of the nanofluid, and T_out and T_in are the outlet and inlet temperatures of the nanofluid, respectively.

Results and discussions

To evaluate the accuracy of the measurements, experimental system was tested with distilled water before measuring the convective heat transfer of nanofluids. Fig. 2 shows the comparison between the measured overall heat transfer coefficient and prediction of Eq. (4) in which h_i is evaluated by Gnielinski correlation for turbulent flow through a tube [18]: $Nu = 0.012 ({Re}^{0.87} - 280) {Pr}^{0.4}$ As shown in Fig. 2, the good agreement exists between the experimental data and predicted values.

Conclusion

In the present experimental study heat transfer behavior of γ-Al₂O₃/water and TiO₂/water nanofluids in a shell and tube heat exchanger was investigated. The experiments were done for a wide range of Peclet numbers, nanoparticle volume concentrations, and for different particle types.

The experimental results for both nanofluids indicate that the heat transfer characteristics of nanofluids improve with Peclet number significantly. Addition of nanoparticles to the base fluid enhances the heat

Acknowledgments

The authors thank the Petrochemical Research and Technology Company at I.R. Iran for its financial support to the present research project.

References (18)

C.H. Li et al.
Experimental investigation of temperature and volume fraction variations on the effective thermal conductivity of nanoparticle suspensions (nanofluids)
J. Appl. Phys.
(2006)
D. Wen et al.
Experimental investigation into convective heat transfer of nanofluids at entrance region under laminar flow conditions
Int. J. Heat and Mass Transfer
(2004)
Y. Yang et al.
Heat transfer properties of nanoparticle-in-fluid dispersions (nanofluids) in laminar flow
Int. J. Heat Mass Transfer
(2005)
S. Zeinali Heris et al.
Experimental investigation of oxide nanofluids laminar flow convective heat transfer
Int. Commun. Heat and Mass Transfer
(2006)
Y. He et al.
Heat transfer and flow behaviour of aqueous suspensions of TiO₂ nanoparticles (nanofluids) flowing upward through a vertical pipe
Int. J. Heat and Mass Transfer
(2007)
H. Chen et al.
Heat transfer and flow behaviour of aqueous suspensions of TiO₂ nanotubes (nanofluids)
Powder Technol.
(2008)
Y. Xuan et al.
Conceptions for heat transfer correlations of nanofluids
Int. J. Heat and Mass Transfer
(2000)
X. Wang et al.
Thermal conductivity of nanoparticle-fluid mixture
J. Thermophys. Heat Transfer
(1999)
S. Lee et al.
Measuring thermal conductivity of fluids containing oxide nanoparticles, transaction of ASME
J. Heat Transfer
(1999)

There are more references available in the full text version of this article.

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Heat transfer of nanofluids in a shell and tube heat exchanger

Abstract

Introduction

Section snippets

Experimental setup

Data processing

Results and discussions

Conclusion

Acknowledgments

J. Appl. Phys.

Int. J. Heat and Mass Transfer

Int. J. Heat Mass Transfer

Int. Commun. Heat and Mass Transfer

Int. J. Heat and Mass Transfer

Powder Technol.

Int. J. Heat and Mass Transfer

Thermal conductivity of nanoparticle-fluid mixture

J. Thermophys. Heat Transfer

Measuring thermal conductivity of fluids containing oxide nanoparticles, transaction of ASME

J. Heat Transfer