TRANSPORT PHENOMENA IN THE IMPACT OF A MOLTEN DROPLET ON A SURFACE: PART II: HEAT TRANSFER AND SOLIDIFICATION

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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HEAT TRANSFER IN MAGNETITE (Fe3O4) NANOPARTICLES SUSPENDED IN CONVENTIONAL FLUIDS: REFRIGERANT-134A (C2H2F4), KEROSENE (C10H22), AND WATER (H2O) UNDER THE IMPACT OF DIPOLE

Heat Transfer Research ◽

10.1615/heattransres.2019029919 ◽

2020 ◽

Vol 51 (3) ◽

pp. 217-232 ◽

Cited By ~ 15

Author(s):

A. Majeed ◽

Ahmed Zeeshan ◽

Muhammad Mubashir Bhatti ◽

R. Ellahi

Keyword(s):

Heat Transfer ◽

Fe3o4 Nanoparticles ◽

Magnetite Fe3o4 ◽

The Impact

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Approximate Analytical Analysis of Unsteady MHD Mixed Flow of Non-Newtonian Hybrid Nanofluid over a Stretching Surface

Fluids ◽

10.3390/fluids6040138 ◽

2021 ◽

Vol 6 (4) ◽

pp. 138

Author(s):

Ali Rehman ◽

Zabidin Salleh

Keyword(s):

Heat Transfer ◽

Differential Equations ◽

Base Fluid ◽

Research Work ◽

Hybrid Nanofluid ◽

Stretching Surface ◽

Optimal Homotopy Analysis Method ◽

Analytical Analysis ◽

Transfer Ratio ◽

The Impact

This paper analyses the two-dimensional unsteady and incompressible flow of a non-Newtonian hybrid nanofluid over a stretching surface. The nanofluid formulated in the present study is TiO2 + Ag + blood, and TiO2 + blood, where in this combination TiO2 + blood is the base fluid and TiO2 + Ag + blood represents the hybrid nanofluid. The aim of the present research work is to improve the heat transfer ratio because the heat transfer ratio of the hybrid nanofluid is higher than that of the base fluid. The novelty of the recent work is the approximate analytical analysis of the magnetohydrodynamics mixed non-Newtonian hybrid nanofluid over a stretching surface. This type of combination, where TiO2+blood is the base fluid and TiO2 + Ag + blood is the hybrid nanofluid, is studied for the first time in the literature. The fundamental partial differential equations are transformed to a set of nonlinear ordinary differential equations with the guide of some appropriate similarity transformations. The analytical approximate method, namely the optimal homotopy analysis method (OHAM), is used for the approximate analytical solution. The convergence of the OHAM for particular problems is also discussed. The impact of the magnetic parameter, dynamic viscosity parameter, stretching surface parameter and Prandtl number is interpreted through graphs. The skin friction coefficient and Nusselt number are explained in table form. The present work is found to be in very good agreement with those published earlier.

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Efficiency Improvement of Miniaturized Heat Exchangers

Fluids ◽

10.3390/fluids6010025 ◽

2021 ◽

Vol 6 (1) ◽

pp. 25

Author(s):

Iris Gerken ◽

Thomas Wetzel ◽

Jürgen J. Brandner

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Heat Exchangers ◽

Assessment Method ◽

Flow Path ◽

Transfer Enhancement ◽

Pressure Losses ◽

Pin Fin ◽

Additional Pressure ◽

The Impact

Micro heat exchangers have been revealed to be efficient devices for improved heat transfer due to short heat transfer distances and increased surface-to-volume ratios. Further augmentation of the heat transfer behaviour within microstructured devices can be achieved with heat transfer enhancement techniques, and more precisely for this study, with passive enhancement techniques. Pin fin geometries influence the flow path and, therefore, were chosen as the option for further improvement of the heat transfer performance. The augmentation of heat transfer with micro heat exchangers was performed with the consideration of an improved heat transfer behaviour, and with additional pressure losses due to the change of flow path (pin fin geometries). To capture the impact of the heat transfer, as well as the impact of additional pressure losses, an assessment method should be considered. The overall exergy loss method can be applied to micro heat exchangers, and serves as a simple assessment for characterization. Experimental investigations with micro heat exchanger structures were performed to evaluate the assessment method and its importance. The heat transfer enhancement was experimentally investigated with microstructured pin fin geometries to understand the impact on pressure loss behaviour with air.

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Ferro-nanofluid squeeze film lubrication with heat transfer

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/13506501211027667 ◽

2021 ◽

pp. 135065012110276

Author(s):

Manimegalai Kavarthalai ◽

Vimala Ponnuswamy

Keyword(s):

Heat Transfer ◽

Heat Transfer Rate ◽

Contact Time ◽

Transfer Rate ◽

Fluid Layer ◽

Darcy Law ◽

Squeeze Film ◽

Mean Temperature ◽

Special Cases ◽

The Impact

A theoretical study of a squeezing ferro-nanofluid flow including thermal effects is carried out with application to bearings and articular cartilages. A representational geometry of the thin layer of a ferro-nanofluid squeezed between a flat rigid disk and a thin porous bed is considered. The flow behaviours and heat transfer in the fluid and porous regions are investigated. The mathematical problem is formulated based on the Neuringer–Rosensweig model for ferro-nanofluids in the fluid region including an external magnetic field, Darcy law for the porous region and Beavers–Joseph slip condition at the fluid–porous interface. The expressions for velocity, fluid film thickness, contact time, fluid flux, streamlines, pathlines, mean temperature and heat transfer rate in the fluid and porous regions are obtained by using a perturbation method. An asymptotic solution for the fluid layer thickness is also presented. The problem is also solved by a numerical method and the results by asymptotic analysis, perturbation and numerical methods are obtained assuming a constant force squeezing state and are compared. It is shown that the results obtained by all the methods agree well with each other. The effects of various parameters such as Darcy number, Beavers–Joseph constant and magnetization parameter on the flow behaviours, contact time, mean temperature and heat transfer rate are investigated. The novel results showing the impact of using ferro-nanofluids in the two applications under consideration are presented. The results under special cases are further compared with the existing results in the literature and are found to agree well.

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