On the Role of Nanofluids in Thermal-hydraulic Performance of Heat Exchangers—A Review

Almurtaji, Salah; Ali, Naser; Teixeira, Joao A.; Addali, Abdulmajid

doi:10.3390/nano10040734

Cited by 41 publications

(33 citation statements)

References 196 publications

(147 reference statements)

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“…The basefluids more commonly used are water, ethylene glycol and oil [ 4 ]. The thermophysical properties of the nanofluids depend on the nature, size and volumetric concentration of the nanoparticles; the nature and physical properties of the base fluid; and the fabrication route, which can be a single-step method or a two-step approach [ 5 ]. The nanoparticles can be made of different materials, such as metals, ceramics and carbons suspended in a base fluid [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…The thermophysical properties of the nanofluids depend on the nature, size and volumetric concentration of the nanoparticles; the nature and physical properties of the base fluid; and the fabrication route, which can be a single-step method or a two-step approach [ 5 ]. The nanoparticles can be made of different materials, such as metals, ceramics and carbons suspended in a base fluid [ 1 , 2 , 3 , 4 , 5 , 6 ]. The size of the mixed solid particles in the base fluid is a relevant parameter to be covered in the development of nanofluids [ 7 ], which can lead to fast sedimentation and viscosity increasing.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, predefining and monitoring the sonication bath temperature leads to the preparation of more stable nanofluids [ 11 ]. However, the introduction of NPs into the base fluids is claimed to significantly enhance the stability and heat transfer performance [ 1 , 2 , 3 , 4 , 5 , 6 ]. Some researchers [ 12 , 13 ] have observed a great increase of the NFs’ thermal conductivity, when compared to conventional coolants; moreover, an enhancement of the convection, which can be natural, forced or mixed [ 14 ], in the nanofluids was also reported by References [ 15 , 16 ], in which grew interest for industrial applications.…”

Section: Introductionmentioning

confidence: 99%

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Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

et al. 2021

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This study addresses the combination of customized surface modification with the use of nanofluids, to infer on its potential to enhance pool-boiling heat transfer. Hydrophilic surfaces patterned with superhydrophobic regions were developed and used as surface interfaces with different nanofluids (water with gold, silver, aluminum and alumina nanoparticles), in order to evaluate the effect of the nature and concentration of the nanoparticles in bubble dynamics and consequently in heat transfer processes. The main qualitative and quantitative analysis was based on extensive post-processing of synchronized high-speed and thermographic images. To study the nucleation of a single bubble in pool boiling condition, a numerical model was also implemented. The results show an evident benefit of using biphilic patterns with well-established distances between the superhydrophobic regions. This can be observed in the resulting plot of the dissipated heat flux for a biphilic pattern with seven superhydrophobic spots, δ = 1/d and an imposed heat flux of 2132 w/m2. In this case, the dissipated heat flux is almost constant (except in the instant t* ≈ 0.9 when it reaches a peak of 2400 W/m2), whilst when using only a single superhydrophobic spot, where the heat flux dissipation reaches the maximum shortly after the detachment of the bubble, dropping continuously until a new necking phase starts. The biphilic patterns also allow a controlled bubble coalescence, which promotes fluid convection at the hydrophilic spacing between the superhydrophobic regions, which clearly contributes to cool down the surface. This effect is noticeable in the case of employing the Ag 1 wt% nanofluid, with an imposed heat flux of 2132 W/m2, where the coalescence of the drops promotes a surface cooling, identified by a temperature drop of 0.7 °C in the hydrophilic areas. Those areas have an average temperature of 101.8 °C, whilst the average temperature of the superhydrophobic spots at coalescence time is of 102.9 °C. For low concentrations as the ones used in this work, the effect of the nanofluids was observed to play a minor role. This can be observed on the slight discrepancy of the heat dissipation decay that occurred in the necking stage of the bubbles for nanofluids with the same kind of nanoparticles and different concentration. For the Au 0.1 wt% nanofluid, a heat dissipation decay of 350 W/m2 was reported, whilst for the Au 0.5 wt% nanofluid, the same decay was only of 280 W/m2. The results of the numerical model concerning velocity fields indicated a sudden acceleration at the bubble detachment, as can be qualitatively analyzed in the thermographic images obtained in this work. Additionally, the temperature fields of the analyzed region present the same tendency as the experimental results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

et al. 2021

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“…S. Almurtaji et al [9] provides a systematic review of the state-of-the-art heat exchanger technology with the primary purpose of to emphasize the importance of how nanofluids can increase the thermal efficiency for future applications. They emphasize that a small number of papers reported that there is an optimum solid concentration at which the thermal-hydraulic performance reaches a maximum level and that the effects of the sedimentation and corrosion by nanofluids need to be explored.…”

Section: Literature Reviewmentioning

confidence: 99%

Thermal Performance in Heat Exchangers by the Irreversibility, Effectiveness, and Efficiency Concepts Using Nanofluids

Nogueira

2020

JES

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The objective of the work is to obtain the outlet temperatures of the fluids in a shell and tube heat exchanger. The second law of thermodynamics is applied through the concepts of efficiency, effectiveness, and irreversibility to analyze the results. Water flows in the shell, and a mixture of water-ethylene glycol is associated with fractions of nanoparticles flows in the tube. Water enters the shell at 27 °C, and the mixture comes to the tube at 90 °C. The mass flow is kept fixed in the shell, equal to 0.23 kg/s, and varies between 0.01 kg/s to 0.50 kg/s. Volume fractions equal to 0.01, 0.10, and 0.25 were considered for analysis, for both nanoparticles from Ag and Al2O3. Results for Reynolds number, heat transfer rate, efficiency, effectiveness, and irreversibility are presented for critique, discussion, and justification of the output data found. It is shown that the flow regime has a significant effect on the performance of the analyzed heat exchanger. Keywords: thermodynamics, second law, ethylene glycol, volume fraction.

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“…Salah Almurtaji et al [6] claim that heat exchangers are used in many applications, such as power plants, air conditioning, and domestic water heating, and that thermo-economic considerations impose the need to develop more efficient equipment. The work developed provides a systematic review of nanofluids' use in heat exchangers to improve thermo-hydraulic performance.…”

Section: Introductionmentioning

confidence: 99%

Effects of R134a Saturation Temperature on a Shell and Tube Condenser with the Nanofluid Flow in the Tube Using the Thermal Efficiency and Effectiveness Concepts

Nogueira¹

2021

WJNSE

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The work's objective is to analyze the influence of the saturation temperature of the R134a refrigerant on the thermal performance of a shell and tube type condenser, with water and aluminum oxide (Al 2 O 3) nanoparticles flowing into the tube. For analysis, the heat exchanger is subdivided into three regions: subcooled liquid, saturated steam, and superheated steam. The shell and tube heat exchanger assumed as the basis for the study has 36 tubes, with rows of 4 tubes in line and three passes into the tube in each region. The parameters used to analyze the performance are efficiency and effectiveness, through variations of quantities such as saturation temperature, the nanofluid's mass flow rate, fraction in the nanoparticles' volume, and the number of passes in the tube in each region of the heat exchanger. The obtained results demonstrate that the efficiency is relatively high in all the analyzed situations. In each saturation temperature, the effectiveness can be increased by introducing fractions of nanoparticles in the water or increasing the number of passes in the tube.

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On the Role of Nanofluids in Thermal-hydraulic Performance of Heat Exchangers—A Review

Cited by 41 publications

References 196 publications

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

Thermal Performance in Heat Exchangers by the Irreversibility, Effectiveness, and Efficiency Concepts Using Nanofluids

Effects of R134a Saturation Temperature on a Shell and Tube Condenser with the Nanofluid Flow in the Tube Using the Thermal Efficiency and Effectiveness Concepts

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