scholarly journals Heat transfer at boiling of R114/R21 refrigerants mixture film on microstructured surfaces

2017 ◽  
Vol 891 ◽  
pp. 012035 ◽  
Author(s):  
O A Volodin ◽  
N I Pecherkin ◽  
A N Pavlenko ◽  
N N Zubkov ◽  
Yu L Bityutskaya
Keyword(s):  
Heat Transfer ◽  
Microstructured Surfaces ◽  
Mixture Film

scholarly journals Capillary-Limited Evaporation From Well-Defined Microstructured Surfaces

2013 ◽  
Author(s):  
Solomon Adera ◽  
Rishi Raj ◽  
Evelyn N. Wang
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Thermal Management ◽  
Latent Heat ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Microstructured Surfaces ◽  
Latent Heat Of Vaporization

Thermal management is increasingly becoming a bottleneck for a variety of high power density applications such as integrated circuits, solar cells, microprocessors, and energy conversion devices. The performance and reliability of these devices are usually limited by the rate at which heat can be removed from the device footprint, which averages well above 100 W/cm2 (locally this heat flux can exceed 1000 W/cm2). State-of-the-art air cooling strategies which utilize the sensible heat are insufficient at these large heat fluxes. As a result, novel thermal management solutions such as via thin-film evaporation that utilize the latent heat of vaporization of a fluid are needed. The high latent heat of vaporization associated with typical liquid-vapor phase change phenomena allows significant heat transfer with small temperature rise. In this work, we demonstrate a promising thermal management approach where square arrays of cylindrical micropillar arrays are used for thin-film evaporation. The microstructures control the liquid film thickness and the associated thermal resistance in addition to maintaining a continuous liquid supply via the capillary pumping mechanism. When the capillary-induced liquid supply mechanism cannot deliver sufficient liquid for phase change heat transfer, the critical heat flux is reached and dryout occurs. This capillary limitation on thin-film evaporation was experimentally investigated by fabricating well-defined silicon micropillar arrays using standard contact photolithography and deep reactive ion etching. A thin film resistive heater and thermal sensors were integrated on the back side of the test sample using e-beam evaporation and acetone lift-off. The experiments were carried out in a controlled environmental chamber maintained at the water saturation pressure of ≈3.5 kPa and ≈25 °C. We demonstrated significantly higher heat dissipation capability in excess of 100 W/cm2. These preliminary results suggest the potential of thin-film evaporation from microstructured surfaces for advanced thermal management applications.

Microstructured Surfaces for Enhanced Pool Boiling Heat Transfer

2011 ◽  
Author(s):  
Kuang-Han Chu ◽  
Ryan Enright ◽  
Evelyn N. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Heat Removal ◽  
Design Guidelines ◽  
Complete Wetting ◽  
Structured Surfaces ◽  
Microstructured Surfaces ◽  
Wide Range

We experimentally investigated pool boiling on microstructured surfaces which demonstrate high critical heat flux (CHF) by enhancing wettability. The microstructures were designed to provide a wide range of well-defined surface roughness to study roughness-augmented wettability on CHF. A maximum CHF of 196 W/cm2 and heat transfer coefficient (h) greater than 80 kW/m2K were achieved. To explain the experimental results, a model extended from a correlation developed by Kandlikar was developed, which well predicts CHF in the complete wetting regime where the apparent liquid contact angle is zero. The model offers a first step towards understanding complex pool boiling processes and developing models to accurately predict CHF on structured surfaces. The insights gained from this work provide design guidelines for new surface technologies with higher heat removal capability that can be effectively used by industry.

Condensation of Low-Surface-Tension Fluids on Microstructured Surfaces at Low Temperature

2017 ◽  
Author(s):  
Abulimiti Aili ◽  
Qiaoyu Ge ◽  
TieJun Zhang
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Low Temperature ◽  
High Surface ◽  
Condensation Heat Transfer ◽  
Lubricant Oil ◽  
Microstructured Surfaces ◽  
Performance Deterioration ◽  
Coated Surface ◽  
Coated Surfaces

Filmwise condensation of a low surface tension fluid (i.e. refrigerant) on microstructured aluminum surfaces is studied to investigate the effect of the structures on condensation heat transfer at low temperature. The hypothesis is that the structures may cause thinning of the condensate film at micro-scales, thus resulting in an enhancement of condensation heat transfer. However, the structures may also decrease the mobility of the condensate near the surface due to increased friction, thus potentially leading to performance deterioration. The aim of this work is to investigate which of the two counteracting mechanisms dominate during filmwise condensation. Condensation experiments are carried out in a low-temperature vacuum chamber. Compared with the Nusselt model of condensation, the microstructured surfaces, either coated or uncoated, show similar performance, with potentially slight enhancement at low subcooling degree and slight deterioration at high subcooling degree. When the microstructured and silane-coated surface is infused with a non-volatile and very low-surface-tension lubricant oil, the lubricant is displaced by the condensate and there is almost no change in the condensation performance. Our results show that, unlike the case of dropwise condensation of high-surface tension fluids, microstructured and coated surfaces with/without infusing oil is not exciting to enhanced filmwise condensation of low-surface-tension fluids.

Heat transfer suppression by suspended droplets on microstructured surfaces

2020 ◽  
Vol 116 (23) ◽  
pp. 233703 ◽  
Author(s):  
Mengyao Wei ◽  
Youngsup Song ◽  
Yangying Zhu ◽  
Daniel J. Preston ◽  
Chuan Seng Tan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Microstructured Surfaces

scholarly journals Heat transfer on microstructured surfaces with pool boiling of various liquids

2020 ◽  
Vol 1677 ◽  
pp. 012080
Author(s):  
R A Aksianov ◽  
Yu S Kokhanova ◽  
E S Kuimov ◽  
R A Ley ◽  
I A Popov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pool Boiling ◽  
Microstructured Surfaces

Heat transfer during the boiling of liquid on microstructured surfaces. Part 2: Visualization of boiling and critical heat fluxes

2013 ◽  
Vol 60 (4) ◽  
pp. 285-294 ◽  
Author(s):  
I. A. Popov ◽  
N. N. Zubkov ◽  
S. I. Kas’kov ◽  
A. V. Shchelchkov
Keyword(s):  
Heat Transfer ◽  
Heat Fluxes ◽  
Microstructured Surfaces

Microstructured Surfaces for Single-Phase Jet Impingement Heat Transfer Enhancement

2013 ◽  
Vol 5 (3) ◽  
Author(s):  
Gilberto Moreno ◽  
Sreekant Narumanchi ◽  
Travis Venson ◽  
Kevin Bennion
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Surface Roughening ◽  
Submerged Jet ◽  
Nusselt Numbers ◽  
Impingement Heat Transfer ◽  
Microstructured Surfaces ◽  
Microporous Coating

An experimental investigation was conducted to examine the use of microstructured surfaces to enhance jet impingement heat transfer. Three microstructured surfaces were evaluated: a microfinned surface, a microporous coating, and a spray pyrolysis coating. The performance of these surface coatings/structures was compared to the performance of simple surface roughening techniques and millimeter-scale finned surfaces. Experiments were conducted using water in both the free- and submerged-jet configurations at Reynolds numbers ranging from 3300 to 18,700. At higher Reynolds numbers, the microstructured surfaces were found to increase Nusselt numbers by 130% and 100% in the free- and submerged-jet configurations, respectively. Potential enhancement mechanisms due to the microstructured surfaces are discussed for each configuration. Finally, an analysis was conducted to assess the impacts of cooling a power electronic module via a jet impingement scheme utilizing microfinned surfaces.

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