Evolution of Microstructure and Surface Characteristics of FeCrAl alloys when Subjected to Flow Boiling Testing

2021 ◽  
pp. 153269
Author(s):  
Rajnikant V. Umretiya ◽  
Donghwi Lee ◽  
Barret Elward ◽  
Mark Anderson ◽  
Raul B. Rebak ◽  
...  
Keyword(s):  
Flow Boiling ◽  
Surface Characteristics ◽  
Fecral Alloys ◽  
Evolution Of Microstructure

Orientation Effects on Flow Boiling Silicon Nanowire Microchannels

2016 ◽  
Author(s):  
Tamanna Alam ◽  
Wenming Li ◽  
Fanghao Yang ◽  
Jamil Khan ◽  
Chen Li
Keyword(s):  
Heat Transfer ◽  
Mass Flux ◽  
Flow Boiling ◽  
Silicon Nanowire ◽  
Heating Surface ◽  
Surface Characteristics ◽  
Nucleate Boiling ◽  
Surface Orientation ◽  
Space Applications ◽  
Thin Film Evaporation

Flow boiling in Silicon Nanowire microchannel enhances heat transfer performance, CHF and reduces pressure drop compared to Plainwall microchannel. It is revealed by earlier studies that promoted nucleate boiling, liquid rewetting and enhanced thin film evaporation are the primary reasons behind these significant performance enchantments. Although flow regime plays a significant role to characterize the flow boiling Silicon Nanowire microchannel performances; surface characteristics, hydrodynamic phenomena, bubble contact angle and surface orientation are also some of the major influencing parameters in system performances. More importantly, effect of orientation (effect of gravity) draws a great attention in establishing the viability of flow boiling in microchannels in space applications. In this study, the effects of heating surface orientation in flow boiling Silicon Nanowire microchannels have been investigated to reveal the underlying heat transfer phenomena and also to discover the applicability of this system in space applications. Comparison between Nanowire and Plainwall microchannels have been performed by experimental and visual studies. Experiments were conducted in a forced convection loop with deionized water at mass flux range of 100kg/m2s – 600kg/m2s. Micro devices consist of five parallel straight microchannels with Nanowire and without Nanowire (Plainwall) (200μm × 250μm × 10mm) were used to investigate the effects of orientation. Two different orientations were used to perform the test: upward facing (0° Orientation) and downward facing (180° Orientation). Results for Plainwall show sensitivity to orientation and mass flux, whereas, little effects of mass flux and orientation have been observed for Nanowire configuration.

Experimental Investigation On the Change in Flow Boiling Characteristics Due to Boiling-Induced Copper Ageing

2021 ◽  
Author(s):  
Prasanna Jayaramu ◽  
Shashwat Jain ◽  
Sateesh Gedupudi ◽  
Sarit Kumar Das
Keyword(s):  
Surface Morphology ◽  
Surface Characterization ◽  
Flow Boiling ◽  
Surface Oxidation ◽  
Surface Characteristics ◽  
Heat Sinks ◽  
Micro Channel ◽  
Fresh Sample ◽  
Characterization Study ◽  
Micro Channels

Abstract Heat sinks and heat exchangers based on flow boiling in mini/micro-channels are expected to be more compact and efficient. One of the major challenges while using copper material for phase-change heat transfer application is the change in surface characteristics after prolonged usage due to the thermal oxidation of surface over time. The present study involves the repeated experimental runs of flow boiling of water in a 1 mm hydraulic diameter end-milled copper channel to verify the influence of ageing on the thermal and hydraulic performance. As it is difficult to measure the surface wettability in a mini/micro-channel, the present work makes use of the ageing and surface characterization study conducted on the dummy copper samples to infer the influence of ageing on mini/micro-channel surface characteristics and consequently its boiling performance. The test involves measuring over a period of time the wetting behaviors of the end-milled copper samples left in water at three different conditions, one in a constant temperature bath maintained at 60 oC and 1 atm and the remaining two in a pool of boiling water at 110 oC and 120 oC. The study compares the fresh sample and the aged sample for the surface oxidation, surface chemical composition and surface morphology, and discusses the changes in contact angle and surface morphology caused by copper ageing.

Effect of heterogeneous wetting surface characteristics on flow boiling performance

2018 ◽  
Vol 70 ◽  
pp. 141-151 ◽  
Author(s):  
Jin Man Kim ◽  
TaeJoo Kim ◽  
Dong In Yu ◽  
Hyunwoo Noh ◽  
Moo Hwan Kim ◽  
...  
Keyword(s):  
Flow Boiling ◽  
Surface Characteristics

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

Medial Smooth Muscle Cell Proliferation in the Balloon Injured Rabbit Aorta: Effect of a Thiazole Compound with Platelet Inhibitory Activity

1984 ◽  
Vol 51 (01) ◽  
pp. 075-078 ◽  
Author(s):  
R G Schaub ◽  
C A Simmons
Keyword(s):  
Smooth Muscle ◽  
Platelet Aggregation ◽  
Balloon Catheter ◽  
Rabbit Aorta ◽  
Surface Characteristics ◽  
Inhibitory Effect ◽  
Lesion Size ◽  
Blue Staining ◽  
Morphologic Characteristics ◽  
Time Period

SummaryTwenty-seven adult male New Zealand rabbits (3–4 kgs) were used in this study. Six rabbits received vehicle, 3 groups of 6 each received doses of 4,5-bis(p-methoxyphenyl)-2-(trifluoromethyl)- thiazole, (U-53,059), at 0.3 mg/kg, 3.0 mg/kg and 30.0 mg/kg/day respectively. Drug and vehicle doses were given orally each day starting 3 days before balloon injury and continuing for the entire 2 week time period. Three rabbits were used as nontreated sham controls. In the vehicle and U-53,059 treated groups aortae were denuded of endothelial cells by balloon catheter injury. Two weeks after injury platelet aggregation to collagen was measured and the aortae removed for analysis of surface characteristics by scanning electron microscopy and lesion size by morphometry. All doses of U-53,059 inhibited platelet aggregation. The 3.0 and 30.0 mg/kg groups had the greatest inhibitory effect. All balloon injured aortae had the same morphologic characteristics. All vessels had similar extent and intensity of Evan’s blue staining, similar areas of leukocyte/platelet adhesion, and a myointimal cell cover of transformed smooth muscle cells. The myointimal proliferative response was not inhibited at any of the drug doses studied.

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