Evaporation From a Capillary Tube

1976 ◽  
Vol 98 (2) ◽  
pp. 178-181 ◽  
Author(s):  
G. Preiss ◽  
P. C. Wayner
Keyword(s):  
Heat Transfer ◽  
Evaporation Rate ◽  
Capillary Tube ◽  
Heat Transfer Characteristics ◽  
Glass Capillary ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Glass Capillary Tube ◽  
Hydrostatic Head ◽  
Meniscus Profile

The heat transfer characteristics of an evaporating ethanol meniscus formed at the exit of a glass capillary tube were studied experimentally. The meniscus profile was photographed and was found to be a function of the evaporation rate and the initial hydrostatic head. The meniscus was found to be stable over a wide range of evaporation rates.

Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

2021 ◽  
pp. 095440622110272
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Litan Kumar Saha ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Transfer Characteristics ◽  
Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

scholarly journals Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 189-200 ◽  
Author(s):  
Primoz Ternik ◽  
Rebeka Rudolf
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Square Cavity ◽  
Onset Of Convection ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Water Based

The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles? volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid?s (i.e. water) Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

Forced Convective Flow of Bingham Plastic Fluids in a Branching Channel With the Effect of T-Channel Branching Angle

2021 ◽  
Vol 143 (5) ◽  
Author(s):  
Anamika Maurya ◽  
Naveen Tiwari ◽  
R. P. Chhabra
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Length Variation ◽  
Heat Transfer Characteristics ◽  
Local Pressure ◽  
Bingham Plastic ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Branching Angle ◽  
Plastic Fluids

Abstract This work aims to explore the T-channel momentum and heat transfer characteristics with the combined effect of Bingham plastic fluids (0.01 ≤ Bn ≤ 20) behavior and geometrical variation in terms of branching angle (30 deg ≤ α ≤ 90 deg). The problem has been solved over a wide range of Reynolds number (50 ≤ Re ≤ 300) and Prandtl number (10 ≤ Pr ≤ 50). For the momentum flow, qualitative and quantitative features are analyzed in terms of streamlines, structure of yielded/unyielded regions, shear rate contours, plug width and length variation, and local pressure coefficient. These features have been represented in terms of isotherm patterns, temperature profile, Nusselt number, and its asymptotic value for heat transfer characteristics. The recirculating flows have been presented here in the vicinity of T-junction, which promote mixing and heat transfer. Broadly, the size of this zone bears a positive dependence on Re and α. However, fluid yield stress tends to suppress it. The critical Reynolds and Bingham numbers were found to be strong functions of the pertinent parameters like α. The inclination angle exerts only a weak effect on the yielded/unyielded regions and on the recirculation length of main branch. Results show a strong relationship of the plug width and length with key parameters and branches. The Nusselt number exhibits a positive relationship with α, Bn, and Re but for lower Pr in the T-junction vicinity for both branches. Such length indicates the required optimum channel length for thermal mixing.

scholarly journals Transient Heat Transfer Characteristics of Twisted Structure Heated by Exponential Heat Flux

2021 ◽  
Vol 9 ◽  
Author(s):  
Li Wang
Keyword(s):  
Heat Transfer ◽  
Penetration Depth ◽  
Heat Generation ◽  
Generation Rate ◽  
Transient Heat Transfer ◽  
Inlet Temperature ◽  
Heat Generation Rate ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Wide Range

This study was conducted to investigate the transient heat transfer characteristics of a twisted structure. The twisted structure was heated according to exponential function (Q=Q0×exp(t/τ), where Q0 is the initial heat generation rate, W/m3; t is time, s; and τ is the period of heat generation rate). A wide range of τ from 37 ms to 14 s was applied for the experimental study. A platinum plate with five pitches (each was 180° twisted with 20 mm in length) was used in the experiment. Helium gas with inlet temperature of 298 K under 500 kPa was used as the coolant. The heat transfer coefficient is found to increase with the decrease of τ, and the transition point was estimated to be at τ≈1s, which means that, when the increasing ratio of heat generation rate satisfies dQdt≥Q0⋅et, the heat transfer enhancement phenomenon will be observed. The response analysis for transient heat transfer at fluid-solid interface was conducted by applying the concept of penetration depth. It is considered that, when the penetration depth is smaller than the thermal boundary thickness, the heat transfer from the interface (wall surface) to the fluid domain is not fully developed during the disturbance.

Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube: Influence of Inner Surface Roughness

2004 ◽  
Author(s):  
Koichi Hata ◽  
Masahiro Shiotsu ◽  
Nobuaki Noda
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Heat Transfer Characteristics ◽  
Subcooled Flow Boiling ◽  
Transfer Characteristics ◽  
Subcooled Flow ◽  
Wide Range ◽  
Inner Surface

The subcooled flow boiling CHF and the heat transfer characteristics for the flow velocities (u=4.0 to 13.3 m/s), the inlet subcoolings (ΔTsub,in=137.49 to 153.87 K), the inlet pressure (Pin=740.67 to 975.78 kPa) and the dissolved oxygen concentration (O=8.63 to 0.0288 ppm) are systematically measured by the experimental water loop installed the pressurizer. The SUS304 tubes of d=3 mm and L=66.5 mm (L/d=22.17) with the inner surfaces of smooth and mirror finished are mainly used in this work. Heat transfer characteristics and CHF data are compared with those for the rough finished inner surface (RF) previously obtained and the CHFs are compared with the values calculated by the CHF correlations against outlet and inlet subcoolings based on the experimental data for the rough finished inner surface under the N2 gas pressure. The influence of inner surface roughness on the heat transfer characteristics and the CHFs for wide range of dissolved gas concentration are investigated in detail.

Effect of Partition Wall Thickness on Heat Transfer Characteristics of a Gas-to-Gas Counterflow Microchannel Heat Exchanger

2009 ◽  
Author(s):  
K. Koyama ◽  
C. Hong ◽  
Y. Asako
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Wall Thickness ◽  
Arbitrary Lagrangian Eulerian ◽  
Heat Transfer Characteristics ◽  
Partition Wall ◽  
Microchannel Heat Exchanger ◽  
Transfer Characteristics ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Wide Range

Effect of partition wall thickness on heat transfer characteristics of a two-stream counterflow gas-to-gas microchannel heat exchanger has been numerically investigated. The flow passages of the microchannel heat exchanger are plane channels of 100 μm in height and 20 mm in length. The partition wall thickness ranges from 20 μm to 200 μm. The material of the partition wall is assumed to be stainless steel. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian method. The computations were performed for a wide range of flow rate to investigate effect of partition wall thickness on heat transfer characteristics of the microchannel heat exchanger. The computational results are presented in form of temperature distributions, bulk temperatures, total temperatures, and heat flux variations along the channels. We have concluded that the partition wall thickness affects significantly heat transfer characteristics of a microchannel heat exchanger.

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