Effect of heat source temperature, nanostructure, and wettability on explosive boiling of ultra-thin liquid argon film over graphene substrate: a molecular dynamics study

2020 ◽  
Vol 16 ◽  
Author(s):  
Haiyan Zhang ◽  
Cunhui Li ◽  
Yi Wang ◽  
Yingmin Zhu ◽  
Weidong Wang
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Heat Source ◽  
Liquid Film ◽  
Substrate Surface ◽  
Thin Liquid Film ◽  
Liquid Argon ◽  
Explosive Boiling ◽  
Source Temperature ◽  
Heat Source Temperature

Background: The study on explosive boiling phenomenon has received increasing attention because it involves many industries, such as advanced micro-, nano-electromechanical and nano-electronic cooling systems, laser steam cleaning and so on. Objective: In present work, the explosive boiling of ultra-thin liquid film over two-dimensional nanomaterial surface in confined space with particular emphasis under the three different influencing factors: various heights of nanostructures, various wetting conditions of solid-liquid interface as well as various heat source temperatures. Methods: Molecular Dynamics simulations (MDs) in present work have been adopted to simulate the whole explosive boiling process. Results: For different heat source temperature case, the higher the heat temperature is, the less time the explosive boiling spends after relaxation. For nanostructure case, nanostructure surface significantly increases heat transfer rate and then leads to the increase of phase transition rate of explosive boiling. For different wetting property case, the increase of surface wettability results in increase of phase transition to some degree. Conclusion: The addition of nanostructures, the higher heat source temperature and good wettability between thin liquid film and substrate surface dramatically improve thermal heat transfer from solid surface to liquid film, which will obviously give rise to explosive boiling occur. in addition, the non-vaporized argon layer still exists in these three factors in spite of continuous thermal transmission from substrate surface to liquid argon film adjacent to solid surface even other vaporized argon atoms.

Molecular Dynamics Study on Explosive Boiling of Thin Liquid Argon Film on Nanostructured Surface Under Different Wetting Conditions

2016 ◽  
Vol 138 (1) ◽  
Author(s):  
Sheikh Mohammad Shavik ◽  
Mohammad Nasim Hasan ◽  
A. K. M. Monjur Morshed
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Liquid Film ◽  
Solid Surface ◽  
Thin Liquid Film ◽  
Liquid Argon ◽  
Spatial And Temporal Variation ◽  
Phase System ◽  
Hydrophilic Surface ◽  
Explosive Boiling

Molecular dynamics (MDs) simulations have been performed to investigate the boiling phenomena of thin liquid film adsorbed on a nanostructured solid surface with particular emphasis on the effect of wetting condition of the solid surface. The molecular system consists of liquid and vapor argon and solid platinum wall. The nanostructures which reside on top of the solid wall have shape of rectangular block. The solid–liquid interfacial wettability, in other words whether the solid surface is hydrophilic or hydrophobic, has been altered for different cases to examine its effect on boiling phenomena. The initial configuration of the simulation domain comprises a three-phase system (solid platinum, liquid argon, and vapor argon), which was equilibrated at 90 K. After equilibrium period, the wall temperature was suddenly increased from 90 K to 250 K which is far above the critical point of argon and this initiates rapid or explosive boiling. The spatial and temporal variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for different cases of wetting conditions of solid surface. The results show that the wetting condition of surface has significant effect on explosive boiling of the thin liquid film. The surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic), and therefore, the liquid argon responds quickly and shifts from liquid to vapor phase faster in the case of hydrophilic surface. The heat transfer rate is also much higher in the case of hydrophilic surface.

Molecular Dynamics Study on Explosive Boiling of Thin Liquid Argon Film on Nanostructured Surface Under Different Wetting Conditions

2015 ◽  
Author(s):  
Sheikh Mohammad Shavik ◽  
Mohammad Nasim Hasan ◽  
A. K. M. Monjur Morshed
Keyword(s):  
Molecular Dynamics ◽  
Liquid Film ◽  
Solid Surface ◽  
Solid Wall ◽  
Thin Liquid Film ◽  
Liquid Argon ◽  
Spatial And Temporal Variation ◽  
Phase System ◽  
Explosive Boiling ◽  
System Pressure

Molecular dynamics (MD) simulations have been performed to investigate the boiling phenomena of thin liquid film adsorbed on a nanostructured solid surface with particular emphasis on the effect of wetting condition of the solid surface. The molecular system consists of liquid and vapor argon, and solid platinum wall. The nanostructures which reside on top of the solid wall have shape of rectangular block. The solid-liquid interfacial wettability, in other words whether the solid surface is hydrophilic or hydrophobic has been altered for different cases to examine its effect on boiling phenomena. The initial configuration of the simulation domain comprised a three phase system (solid platinum, liquid argon and vapor argon) which was equilibrated at 90 K. After equilibrium period, the wall temperature was suddenly increased from 90 K to 250 K which is far above the critical point of argon and this initiates rapid or explosive boiling. The spatial and temporal variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for different cases of wetting conditions of solid surface. The results show that the wetting condition of surface has significant effect on explosive boiling of the thin liquid film. The surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface.

scholarly journals Wind tunnel test of an anti-icing approach by heat pipe for wind turbine bladesunder the rime ice condition

2021 ◽  
Vol 25 (6 Part B) ◽  
pp. 4485-4493
Author(s):  
Xiao-Juan Li ◽  
Wen-Feng Guo ◽  
Yan Li ◽  
Zhi Xu ◽  
Fang Feng
Keyword(s):  
Heat Transfer ◽  
Wind Tunnel ◽  
Heat Source ◽  
Wind Turbine ◽  
Heat Pipe ◽  
Turbine Blade ◽  
Blade Surface ◽  
Source Temperature ◽  
Temperature Conditions ◽  
Heat Source Temperature

The icing events for the wind turbine blade is the key problem in the low temperature conditions. Heating is considered to be the most efficient approach to prevent from the ice formation on the turbine blade surface. However, this kind of method consumes a certain amount of energy. In this present study, an anti-icing method, using the heat pipe technology, is proposed to prevent from icing on the blade surface, and the anti-icing energy is from the waste heat generated during the operation of a wind turbine, which can reduce the assumption of the energy. The researches on the anti-icing temperature characteristics of the test model, based on the heat pipe anti-icing method, are carried out in an icing wind tunnel combining with the low natural temperature. The effects of the wind speed and heat source temperature on the heat transfer of heat pipes are investigated. The icing distribution and the temperature change of the anti-icing process of an airfoil with NACA0018 are explored, and the variation of the icing thickness of the airfoil with icing time, under the different heat source temperature conditions, is analyzed. The results indicate that the blade surface temperature, which is lower than 0?C, is more beneficial to the heat transfer of the heat pipe, and the ice prevention, based on the heat transfer of the heat pipe, can achieve a better anti-icing effect.

scholarly journals Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

2011 ◽  
Vol 32 (3) ◽  
pp. 57-70 ◽  
Author(s):  
Dariusz Mikielewicz ◽  
Jarosław Mikielewicz
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
Heat Source ◽  
Silicone Oil ◽  
Hot Water ◽  
Working Fluid ◽  
Preliminary Heating ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Steam Heat

Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

Fast forced liquid film spreading on a substrate: flow, heat transfer and phase transition

2010 ◽  
Vol 656 ◽  
pp. 189-204 ◽  
Author(s):  
ILIA V. ROISMAN
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Stokes Equations ◽  
Substrate Surface ◽  
Reynolds Numbers ◽  
Drop Impact ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Theoretical Predictions ◽  
Viscous Drop

This theoretical study is devoted to description of fluid flow and heat transfer in a spreading viscous drop with phase transition. A similarity solution for the combined full Navier–Stokes equations and energy equation for the expanding lamella generated by drop impact is obtained for a general case of oblique drop impact with high Weber and Reynolds numbers. The theory is applicable to the analysis of the phenomena of drop solidification, target melting and film boiling. The theoretical predictions for the contact temperature at the substrate surface agree well with the existing experimental data.

A Study on the Cooling Characteristics of TMA Clathrate Compound with Additives

2006 ◽  
Vol 326-328 ◽  
pp. 1275-1278 ◽  
Author(s):  
Chang Oh Kim ◽  
Jin Heung Kim ◽  
Nak Kyu Chung
Keyword(s):  
Heat Source ◽  
Phase Change ◽  
Specific Heat ◽  
Freezing Point ◽  
Phase Change Temperature ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Clathrate Compound ◽  
Supercooling Degree ◽  
Change Temperature

This study aims to find out cooling characteristics of TMA 25wt%-water clathrate compound with ethanol such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at -6, -7 and -8, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as 5.1 and 5.0, 3.8 according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is 0.9 and minimum supercooling is 0.8, 0.7 according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is 3.013~3.048 kJ/kgK according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol.

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