Electrohydrodynamic enhancement of in-tube convective condensation heat transfer

Convective Boiling With Electrohydrodynamic Enhancement: The Influence of Inlet Quality

“…Recently, with regard to improving heat transfer in shell and tube heat exchangers, researchers have experimentally investigated the EHD technique with convective boiling in tubes while using visualization techniques, such as highspeed videography, to elucidate the behavior of the fluid within tubular test sections of similar geometry to that used in this study (Singh et al, 1995;Bryan and Seyed-Yagoobi, 2000;Cotton, 2000;Cotton et al, 2001Cotton et al, , 2005Sadek, 2004;Sadek et al, 2006Sadek et al, , 2008Di Marco, 2012). Previous research, such as that of Cotton et al (2005Cotton et al ( , 2012 and McGranaghan and Robinson (2014a) have shown that both direct current (DC) and alternating current (AC) electric fields can have a significant influence on the two-phase heat transfer.…”

“…In the previous works of Cotton et al (2005Cotton et al ( , 2012 and Sadek et al (2006) the tube and shell heat exchanger test sections used were limited by the fact that the working fluid flowed on the tube side and the tube needed to be electrically and thermally conductive, necessitating the use of opaque metallic sections to measure thermal hydraulic behavior under the influence of EHD. Visualization was often performed at a viewing window at the test section exit, which is not ideal since conditions are adiabatic and may not give details of flow regime development along the test section.…”

“…One such method, electrohydrodynamics (EHD) can offer increased heat transfer rates while the high-voltage low-current phenomenon allows electric fields to be established that can radically alter the flow patterns with low electrical power requirement (Cotton et al, 2012;Di Marco, 2012) and low pressure drop penalties (McGranaghan and Robinson, 2014a). However, the mechanisms by which EHD influences the fluid flow and heat transfer within a closed heat exchanger are still not thoroughly understood, although significant progress is ongoing (Cotton et al, 2005(Cotton et al, , 2012Sadek et al, 2006Sadek et al, , 2008Ng, 2010;Di Marco, 2012;McGranaghan and Robinson, 2014a,b). For two-phase flows subject to EHD, Jones (1979), Chang and Watson (1994), Cotton et al (2012), and Di Marco (2012), among others, posed the following expression for the forces induced on a dielectric medium within an electric field:…”

Combined heat and mass transfer for laminar flow of moist air in a 3D rectangular duct: CFD simulation and validation with experimental data

“…Its application is found in many diverse fields but not limited to cleaning operations, curing of plastics, manufacturing of pulp-insulated cables, many chemical processes, building sciences [1][2][3], food processes [4], condensation and frosting of heat exchangers [5][6][7], moisture transfer between flowing air and porous media [8] and atmospheric flows. The study of convection reduces to the determination of convective heat and mass transfer coefficients.…”

Convective mass transfer coefficient for a hydrodynamically developed airflow in a short rectangular duct

“…The convective mass transfer coefficient is an important parameter, since it is a measure of the resistance to mass transfer between the fluid flowing in a duct and the surface of the duct. The convective coefficient depends on the hydrodynamic, thermal and concentration boundary layers and is an important parameter when studying moisture and contaminant transfer between flowing air and porous media [1][2][3][4], as well as condensation and frosting in heat exchangers [5][6][7]. Despite its importance, there are few experimental data available in the literature on convective mass transfer coefficients for ducts.…”