Controlling Nucleate Boiling Heat Transfer Performance on Micro/Nano Textured Surfaces Using Surfactants and Electric Field

Project: Research

View graph of relations

Description

Nucleate boiling is one of most effective methods for transferring large amounts of heat by liquid-vapor phase change process. It has widespread applications in high heat flux dissipation and thermal management devices. Therefore, to improve overall heat transfer performance, the increase in both critical heat flux (CHF) and heat transfer coefficient (HTC) is required. The aim of this work is to devise a control mechanism in which CHF and HTC can be enhanced and tuned on demand and independently of surface modifications, and therefore the same boiling system could be used for the high heat flux dissipation and the thermal management applications. A great deal of work has been done showing the enhancement in HTC when surfactants are added into working fluids. This enhancement is often associated with two mechanisms; change in surface tension due to surfactant adsorption to liquid-vapor interface and change in surface wettability due to surfactant adsorption to liquid-solid interface (heater surface). Recently, a significant enhancement in boiling heat transfer performance of an order of magnitude was observed when a small electric potential (~1V) was used in addition to surfactant. However, only few studies have considered the surface roughness effects for surfactant solutions and those were limited to just random roughness and without electric field. As for the CHF, many studies have proved a significant enhancement when micro/nano textured surfaces are used. This enhancement is often attributed to parameters such as roughness, wettability and wicking behavior but is still not completely understood. Therefore, it is encouraging to combine the nucleate boiling on micro/nano textured surfaces with the surfactants and the electric field in order to further enhance and control the boiling heat transfer performance. First, nucleate boiling without electric field on micro/nano textured surfaces for different roughness values and surfactants types will be investigated. Secondly, a small electric field in combination with surfactant will be introduced to control the surface wettability, and thus the heat transfer enhancement. The usage of electric field and surfactants will allow changing surface wettability without affecting surface tension of the bulk fluid and independently of surface roughness, which will also help understanding the basic mechanism of CHF enhancement. Besides, to check the long-term working of boiling process, boiling system robustness and durability over long time-periods will be investigated also. Finally, to get deep insight of surfactant effects on bubble dynamics, numerical simulations using lattice Boltzmann method (LBM) method will be conducted. 

Detail(s)

Project number9042977
Grant typeGRF
StatusActive
Effective start/end date1/01/21 → …