Optimization of Nodule and Height Sizes for Mixed Hydrophilic and Hydrophobic Surfaces

2020 ◽  
Author(s):  
Brian Frymyer ◽  
Alparslan Oztekin
Keyword(s):  
Energy Barrier ◽  
Patterned Surfaces ◽  
Dropwise Condensation ◽  
Diffusion Flow ◽  
Flow Rates ◽  
Condensation Surface ◽  
Surface Performance ◽  
Hydrophilic Materials ◽  
Mass Collection ◽  
Hydrophilic And Hydrophobic Surfaces

Abstract Patterned surfaces of hydrophobic and hydrophilic materials are considered to sustain dropwise condensation, providing the benefits of both materials and creating a surface with a low energy barrier for nucleation and capable of sustaining dropwise condensation. Surface heights, nodule sizes, and flow rates are evaluated on square-patterned surfaces to maximize mass collection. A thermal model is used to assess surface performance and includes an equivalent thermal resistance for diffusion. Flow rates of 15, 25, 50, and 100 m/s with nodule sizes between 0.1 mm to 3.6 mm are evaluated. Surface heights of 0.25, 0.5, 1, and 2 m are also assessed. For flow rates greater than 50 m/s, turbulent flow optimum nodule size is between 0.2 mm and 0.6 mm. Surfaces greater than 1 m in height at flow rates less than 50 m/s maximize mass with nodule sizes of 1.4 mm and 2 mm.

Optimization of Mixed Hydrophilic and Hydrophobic Surfaces Under Laminar Flow Conditions

2020 ◽  
Author(s):  
Brian Frymyer ◽  
Alparslan Oztekin
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Thermal Resistance ◽  
Energy Barrier ◽  
High Energy ◽  
Film Condensation ◽  
Dropwise Condensation ◽  
Flow Conditions ◽  
Mass Collection ◽  
Laminar Flow Conditions

Abstract When condensation first forms on a surface, it starts as tiny droplets. As the surface continues to collect condensation, the droplets grow together and form a film. The film increases the thermal resistance of the system. It is possible to remove the fluid from the condensing surface before it develops into a film. Dropwise condensation has the capability of providing up to an order of magnitude higher heat transfer than film condensation. A hydrophobic surface is capable of sustaining dropwise condensation but creates a high energy barrier that restricts nucleation. A hydrophilic surface has a low energy barrier for nucleation but retains the water quickly transitioning to film condensation. A hydrophilic and hydrophobic patterned surface creates a surface with a low nucleation energy barrier and is capable of sustaining dropwise condensation. Surface patterns are evaluated under laminar flow conditions to maximize mass collection. The surfaces are evaluated using a thermal model, which includes an equivalent thermal resistance for diffusion. Laminar flow rates are evaluated using Reynolds numbers from 1,218 to 4 × 105. Hydrophilic nodules sizes are evaluated from 0.1 mm to 3.7 mm. Under natural convection flow, mass collection can be increased by 20% with respect to film heat transfer.

Enabling efficient energy barrier computations of wetting transitions on geometrically patterned surfaces

Soft Matter ◽  
2013 ◽  
Vol 9 (40) ◽  
pp. 9624 ◽  
Author(s):  
Nikolaos T. Chamakos ◽  
Michail E. Kavousanakis ◽  
Athanasios G. Papathanasiou
Keyword(s):  
Energy Barrier ◽  
Patterned Surfaces ◽  
Wetting Transitions ◽  
Efficient Energy

scholarly journals Enhanced dropwise condensation on heterogeneously hybrid patterned surfaces

2021 ◽  
pp. 101319
Author(s):  
Hai Wang ◽  
Xin Zhao ◽  
Junfeng Wang ◽  
Zhentao Wang ◽  
Dongbao Wang ◽  
...  
Keyword(s):  
Patterned Surfaces ◽  
Dropwise Condensation

scholarly journals Numerical simulation of dropwise condensation over hydrophobic surfaces using vapor-diffusion model

2021 ◽  
Vol 2116 (1) ◽  
pp. 012011
Author(s):  
N Suzzi ◽  
G Croce
Keyword(s):  
Heat Transfer ◽  
Diffusion Model ◽  
Lagrangian Model ◽  
Dropwise Condensation ◽  
Velocity Range ◽  
Air Velocity ◽  
Hydrophobic Surfaces ◽  
Vapor Diffusion ◽  
Condensation Model ◽  
Hydrophilic And Hydrophobic Surfaces

Abstract Dropwise condensation of humid air over hydrophilic and hydrophobic surfaces is numerically investigated using a phenomenological, Lagrangian model. Mass flux through droplets free surface is predicted via a vapor-diffusion model. Validation with literature experimental data is successfully conducted at different air humidities and air velocities. The accuracy of the implemented condensation model is compared with a standard analogy between convective heat and mass transfer, showing that the latter is not able to predict heat transfer performances in the investigated air velocity range.

Wetting Mode Evolution of Steam Dropwise Condensation on Superhydrophobic Surface in the Presence of Noncondensable Gas

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Xuehu Ma ◽  
Sifang Wang ◽  
Zhong Lan ◽  
Benli Peng ◽  
H. B. Ma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Superhydrophobic Surface ◽  
Contact Angle Hysteresis ◽  
High Surface ◽  
Dropwise Condensation ◽  
Noncondensable Gas ◽  
Order Of Magnitude ◽  
Rapid Removal ◽  
Condensation Surface

It is well known that heat transfer in dropwise condensation (DWC) is superior to that in filmwise condensation (FWC) by at least one order of magnitude. Surfaces with larger contact angle (CA) can promote DWC heat transfer due to the formation of “bare” condensation surface caused by the rapid removal of large condensate droplets and high surface replenishment frequency. Superhydrophobic surfaces with high contact angle (> 150°) of water and low contact angle hysteresis (< 5°) seem to be an ideal condensing surface to promote DWC and enhance heat transfer, in particular, for the steam-air mixture vapor. In the present paper, steam DWC heat transfer characteristics in the presence of noncondensable gas (NCG) were investigated experimentally on superhydrophobic and hydrophobic surfaces including the wetting mode evolution on the roughness-induced superhydrophobic surface. It was found that with increasing NCG concentration, the droplet conducts a transition from the Wenzel to Cassie-Baxter mode. And a new condensate wetting mode—a condensate sinkage mode—was observed, which can help to explain the effect of NCG on the condensation heat transfer performance of steam-air mixture on a roughness-induced superhydrophobic SAM-1 surface.

Automation of Process Control in Chemical Plant

2015 ◽  
Vol 2 (1) ◽  
pp. 6-12
Author(s):  
Agus Sugiarta ◽  
Houtman P. Siregar ◽  
Dedy Loebis
Keyword(s):  
Process Control ◽  
Pid Control ◽  
Control Algorithm ◽  
Chemical Engineering ◽  
Chemical Plant ◽  
Raw Material ◽  
Flow Rates ◽  
Material Supply ◽  
Wide Range ◽  
Inherent Problem

Automation of process control in chemical plant is an inspiring application field of mechatronicengineering. In order to understand the complexity of the automation and its application requireknowledges of chemical engineering, mechatronic and other numerous interconnected studies.The background of this paper is an inherent problem of overheating due to lack of level controlsystem. The objective of this research is to control the dynamic process of desired level more tightlywhich is able to stabilize raw material supply into the chemical plant system.The chemical plant is operated within a wide range of feed compositions and flow rates whichmake the process control become difficult. This research uses modelling for efficiency reason andanalyzes the model by PID control algorithm along with its simulations by using Matlab.

Sign in / Sign up

Export Citation Format

Share Document