scholarly journals Experimental Investigation on the Effects of Ethanol-Enhanced Steam Injection Remediation in Nitrobenzene-Contaminated Heterogeneous Aquifers

2021 ◽  
Vol 11 (24) ◽  
pp. 12029
Author(s):  
Ruxue Liu ◽  
Xinru Yang ◽  
Jiayin Xie ◽  
Xiaoyu Li ◽  
Yongsheng Zhao
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Organic Compounds ◽  
Marangoni Convection ◽  
Steam Injection ◽  
Average Concentration ◽  
Low Permeability ◽  
Heterogeneous Aquifers ◽  
Heterogeneous Aquifer ◽  
Mass And Heat Transfer

Steam injection is an effective technique for the remediation of aquifers polluted with volatile organic compounds. However, the application of steam injection technology requires a judicious selection of stratum media because the remediation effect of hot steam in heterogeneous layers with low permeability is not suitable. In this study, the removal effect of nitrobenzene in an aquifer was investigated through a series of two-dimensional sandbox experiments with different stratigraphic structures. Four types of alcohols were used during steam injection remediation to enhance the removal effect of nitrobenzene (NB)-contaminated heterogeneous aquifers. The principle of the removal mechanism of alcohol-enhanced organic compounds is that alcohols can reduce the surface tension of the contaminated water, resulting in Marangoni convection, thereby enhancing mass and heat transfer. The addition of alcohol may also reduce the azeotropic temperature of the system and enhance the volatility of organic compounds. The study revealed that all four alcohol types could reduce the surface tension from 72 mN/m to <30 mN/m. However, among these, only ethanol reduced the azeotropic temperature of NB by 15 °C, thereby reducing energy consumption and remediation costs. Therefore, ethanol was selected as an enhancing agent to reduce both surface tension and azeotropic temperature during steam injection. In the 2-D simulation tank, the interface between the low-and high-permeability strata in the layered heterogeneous aquifer had a blocking effect on steam transportation, which in turn caused a poor remediation effect in the upper low-permeability stratum. In the lens heterogeneous aquifer, steam flows around the lens, thereby weakening the remediation effect. After adding ethanol to the low-permeability zone, Marangoni convection was enhanced, which further enhanced the mass and heat transfer. In the layered and lens heterogeneous aquifers, the area affected by steam increased by 13% and 14%, respectively. Moreover, the average concentration of NB was reduced by 51% in layered heterogeneous aquifers and by 58% in low-permeability lenses by ethanol addition. These findings enhance the remediation effect of steam injection in heterogeneous porous media and contribute to improve the remediation efficiency of heterogeneous aquifers by steam injection.

Experimental Analysis of the Heat Transfer Induced by Thermocapillary Convection Around a Bubble

1999 ◽  
Vol 122 (1) ◽  
pp. 66-73 ◽  
Author(s):  
P. Arlabosse ◽  
L. Tadrist ◽  
H. Tadrist ◽  
J. Pantaloni
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Heat Flux ◽  
Temperature Gradient ◽  
Marangoni Convection ◽  
Heated Wall ◽  
Meridian Plane ◽  
Oil Viscosity ◽  
Dimensionless Numbers ◽  
Wide Range

The surface tension driven flow in the liquid vicinity of gas bubbles on a heated wall and its contribution to the heat transfer are investigated experimentally in a configuration where surface tension force and buoyancy forces oppose one another. This liquid flow caused by the temperature gradient along the interface is called thermocapillary or thermal Marangoni convection. The studies were made with silicone oils of different viscosities so that a wide range of dimensionless numbers were encountered. The velocity fields are determined from the motion of carbon particles in the meridian plane of the bubble. The influence of the temperature gradient, the oil viscosity, and the bubble shape on the profiles along the interface and in the direction normal to the interface is analyzed. The temperature field is determined by holographic interferometry. For the axisymmetric problem, the interferograms are evaluated by solving the Abel-integral equation. From the isotherms, the temperature distribution along the bubble surface and in the liquid beneath the bubble is measured. To quantify the contribution of thermocapillarity to the heat transfer, the heat flux transferred by thermocapillarity is measured. A heat exchange law giving the increase in heat flux due to Marangoni convection in comparison to the conductive regime is proposed. [S0022-1481(00)70501-9]

Transient Thermo-Diffuso-Capillary Convection Around a Bubble in a Surfactant Solution: A Numerical Investigation Using the Volume-of-Fluid Technique

2019 ◽  
Author(s):  
D. S. Kalaikadal ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Heat Transfer Enhancement ◽  
Marangoni Number ◽  
Marangoni Convection ◽  
Surface Tension Gradient ◽  
Accurate Estimation ◽  
Interface Temperature ◽  
Transfer Enhancement ◽  
Capillary Flows

Abstract Marangoni Convection occurs when a surface tension gradient is established at a liquid-gas interface. The variation in surface tension could be driven by an interface temperature gradient, resulting in Thermocapillary Convection, or by an interface concentration gradient, giving rise to Diffuso-Capillary Convection, or a combination of both. Such flows are found to be of interest in microgravity (and otherwise), as they are known to significantly contribute to heat and mass transfer enhancement at the interface. This paper deals with the computational study of bubble induced thermo-diffuso capillary convection in the presence of surfactants and a stratified thermal field. Bubble induced thermo-capillary convection in a pure liquid has been substantially studied and the effects of various parameters like liquid properties, wettability, bubble size, channel depth, and temperature gradients on the strength of thermo-capillary currents and the associated heat transfer enhancement at the bubble interface are well established. In this study the physico-chemical properties of an aqueous solution of Sodium-Dodecyl-Sulphate (SDS), a surfactant, were used to introduce the effects of surfactant concentration-induced surface-tension gradients in addition to the temperature induced gradients. Unlike in purely thermo-capillary flows, where the interface sees a near-constant surface-tension gradient from base to apex, the presence of surfactant molecules at the interface results in gradients that vary significantly along the interface with maximum gradients at the bubble base and the apex, resulting in a pair opposing vortices anchored to the bubble interface. The presence of the opposing vortices, results in weaker capillary-flows at higher thermal Marangoni numbers. This is in contrast with purely thermal Marangoni convection, where a larger Marangoni number yields a stronger capillary flow. It was also observed that while the Marangoni number may provide an accurate estimation of heat-transfer enhancement under steady-state conditions, it may not be possible in the case of a transiently developing Marangoni-flow. The heat transfer enhancement is maximum near the time of bubble introduction and then diminishes to a lower, stable value. Also, the capillary flows and the associated heat transfer is found to significantly vary with the wetting behavior at the liquid-solid-vapor interface, even for the same set of Marangoni numbers.

scholarly journals Mass and Heat Transfer Coefficients in Automotive Exhaust Catalytic Converter Channels

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 507
Author(s):  
Chrysovalantis C. Templis ◽  
Nikos G. Papayannakos
Keyword(s):  
Heat Transfer ◽  
Flow Reactor ◽  
Catalytic Converter ◽  
Reaction Rates ◽  
Cfd Model ◽  
Automotive Exhaust ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Wide Range ◽  
Mass And Heat Transfer

Mass and heat transfer coefficients (MTC and HTC) in automotive exhaust catalytic monolith channels are estimated and correlated for a wide range of gas velocities and prevailing conditions of small up to real size converters. The coefficient estimation is based on a two dimensional computational fluid dynamic (2-D CFD) model developed in Comsol Multiphysics, taking into account catalytic rates of a real catalytic converter. The effect of channel size and reaction rates on mass and heat transfer coefficients and the applicability of the proposed correlations at different conditions are discussed. The correlations proposed predict very satisfactorily the mass and heat transfer coefficients calculated from the 2-D CFD model along the channel length. The use of a one dimensional (1-D) simplified model that couples a plug flow reactor (PFR) with mass transport and heat transport effects using the mass and heat transfer correlations of this study is proved to be appropriate for the simulation of the monolith channel operation.

Sign in / Sign up

Export Citation Format

Share Document