Heat and mass transfer from annular fins of different cross sectional area. Part II. Optimal dimensions of fins

2012 ◽  
Vol 35 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Abdurrahman Moinuddin ◽  
Mostafa H. Sharqawy ◽  
Syed M. Zubair
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Annular Fins

New Correlative Models for Fully Developed Turbulent Heat and Mass Transfer in Circular and Noncircular Ducts

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Zhipeng Duan
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Turbulent Transport ◽  
Cross Sectional Area ◽  
Turbulent Heat ◽  
Square Root ◽  
Sectional Area ◽  
Cross Sectional ◽  
Dimensionless Parameters ◽  
Simple Models

Fully developed turbulent flow in noncircular ducts is examined, and simple models are proposed to predict the friction, heat and mass transfer in most common noncircular channels. It is found that the square root of cross-sectional area is the relatively more appropriate length scale to use in defining the dimensionless parameters to ensure similarity between the circular and most noncircular ducts. By using the dimensionless parameters based on the square root of cross-sectional area, it is demonstrated that the circular tube relations may be applied to most noncircular ducts eliminating large errors in estimation. As turbulent transport phenomena are inherently complex and there, currently, is no extensive experimental data for turbulent heat and mass transfer in noncircular ducts, the simple models are valuable in spite of their limitations.

Influence of the Cross Sectional Area of a Separation Column Using Structured Packing

2003 ◽  
Author(s):  
Rosa H. Cha´vez ◽  
Javier de J. Guadarrama ◽  
Osbaldo Pe´rez ◽  
Abel Herna´ndez-Guerrero
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Separation Efficiency ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Structured Packing ◽  
Separation Column ◽  
Transfer Unit ◽  
The Cross

In order to determine the dimension of a separation column, hydrodynamic and mass transfer models are necessary to evaluate the pressure drop and the height of the global mass transfer unit, respectively. Those parameters are a function of the cross sectional area of the column. The present work evaluates the dependency of the pressure drop and height of the global transfer unit with respect to the cross sectional area of the column, using an absorption column with high efficiency structured packing, in order to recover SO2 in the form of NaHSO3, as an example. An optimization was done applying Two Film model which is based on the number of global mass transfer units of both gas and liquid, involving the separation efficiency in terms of the height of a global transfer unit. Structured packing, geometrically heaped in a separation column, has been achieving wider acceptance in the separation processes due to their geometric characteristics that allow them to have greater efficiency in the separation processes. Three different structured packing were evaluated in this work. The results show how ININ packing is one of the packings does the best work having the highest separation efficiency because it has the lowest height of the global mass transfer unit and Mellapak packing has the largest capacity because it manages the largest liquid and gas flows. An analysis is done with respect to the pressure drop through the system for all packings considered, and a discussion is presented for each hydrodynamic and mass transfer parameter studied.

scholarly journals Study on the Decoupled Transfer of Heat and Mass in Wire Variable Polarity Plasma Arc Welding

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1073 ◽  
Author(s):  
Fan Jiang ◽  
Cheng Li ◽  
Bin Xu ◽  
Shinichi Tashiro ◽  
Manabu Tanaka ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Base Metal ◽  
Plasma Arc ◽  
Sectional Area ◽  
Cross Sectional ◽  
Variable Polarity ◽  
Arc Shape ◽  
Variable Polarity Plasma Arc

A hybrid arc-wire welding method based on the variable polarity plasma arc (VPPA) and variable polarity pulse metal inert-gas (VP-PMIG) was proposed for manufacturing aluminum alloys. This paper aims to clarify the decoupling control process of heat and mass transfer in the hybrid welding process. To understand the arc physics and analyze the mass transfer behavior, the hybrid arc shape and droplet cross-sectional area with different parameters were obtained by high speed video photography. Further, the melting area of the base metal was analyzed by macro-metallography of the weld bead cross-section to study the heat transfer. It is found that the hybrid arc shape changes with time. The VPPA main arc is deflected to one side by the VP-PMIG, making the temperature distribution asymmetric, and during the VP-PMIG pulse necking occurs. The cross-sectional area of the droplet is more obviously affected by the VP-PMIG current than the VPPA current. Meanwhile, the VPPA current dominates the melting area of the base metal. Therefore, we conclude that heat transfer to the base metal is from the VPPA, while droplet transfer is mainly controlled by the VP-PMIG arc. These conclusions are confirmed by analyzing the decoupling degree of heat and mass transfer of the base metal by the VPPA and VP-PMIG arc.

scholarly journals Mass transfer in 3D printed electrolyzers: The importance of inlet effects

2020 ◽  
Author(s):  
Stéphane Weusten ◽  
Luc Murrer ◽  
Matheus de Groot ◽  
John van der Schaaf
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Turbulent Flow ◽  
Cross Sectional Area ◽  
Transfer Performance ◽  
Sectional Area ◽  
Entrance Length ◽  
Cross Sectional ◽  
3D Printed ◽  
The Cross

This paper investigates the effect of inlet shape, entrance length and turbulence promoters on mass transfer by using 3D printed electrolyzers. Our results show that the inlet design can promote turbulence and lead to an earlier transition to turbulent flow. The Reynolds number at which the transition occurs can be predicted by the ratio of the cross-sectional area of the inlet to the cross-sectional area of the electrolyzer channel. A longer entrance length results in more laminar behavior and a later transition to turbulent flow. With an entrance length of 550mm, the inlet design did no longer affect the mass transfer performance significantly. The addition of gyroid type turbulence promoters resulted in a factor 2 to 4 increase in mass transfer depending on inlet design, entrance length and the type of promoter. From one configuration to another, there was a minimal variation in pressure drop (<16 mbar).

Functioning of Conducting Elements of Phloem and Xylem in the Stalk of the Developing Fruit of Lupinus albus L

1978 ◽  
Vol 5 (3) ◽  
pp. 321 ◽  
Author(s):  
JS Pate ◽  
J Kuo ◽  
PJ Hocking
Keyword(s):  
Mass Transfer ◽  
Dry Matter ◽  
Xylem Sap ◽  
Cross Sectional Area ◽  
White Lupin ◽  
Sectional Area ◽  
Weight Changes ◽  
Specific Mass ◽  
Cross Sectional ◽  
Sieve Tubes

The economy of water and dry matter in fruits of white lupin (L. albus L.) was studied by measuring transpiration, CO2 exchange and weight changes over an 8-week growth period. These data were combined with analyses of upper stem tracheal (xylem) sap and fruit tip phloem sap to estimate rates of import of dry matter and water through xylem and phloem. Assuming unidirectional mass flow to operate, phloem carried 97 % of the dry matter and 27 % of the water entering the fruit, and xylem supplied the remainder of the water, 30 % of the minerals and 10 % of the amino compounds. The structure of fruit stalks of various age was examined by light microscopy. Cross-sectional areas occupied by different tissues were measured, and numbers and mean transverse areas of conducting elements estimated. Sieve tubes comprised 0.66-1.13% of the stalk's cross-sectional area, vessels plus tracheids 0.27 - 0.50%. Secondary xylem consisted mainly of fibres. Sieve tubes occupied 18 - 27% of the phloem cross-sectional area. The fully grown stalk showed approximately three times as many sieve tubes in transverse section as vessels plus tracheids. Transfer of dry matter and water through the fruit stalk was highest during the exponential phase of fruit growth. Peak specific mass transfer in sieve tubes was 3.95 g dry matter per square centimetre of sieve tube per hour, in tracheids plus vessels 0.28 g cm2 h-1. Maximum flow velocity in sieve tubes was 22 cm h-1, in tracheids plus vessels, 147 cm h-1. Values for specific mass transfer and flow velocities were several times less in stalks of very young or near-mature fruits.

Novel Wire Mesh Packing with Controllable Cross-Sectional Area in a Rotating Packed Bed: Mass Transfer Studies

2020 ◽  
Vol 59 (36) ◽  
pp. 16043-16051
Author(s):  
Zhang-Nan Wen ◽  
Wei Wu ◽  
Yong Luo ◽  
Liang-Liang Zhang ◽  
Bao-Chang Sun ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Packed Bed ◽  
Cross Sectional Area ◽  
Wire Mesh ◽  
Sectional Area ◽  
Cross Sectional ◽  
Rotating Packed Bed ◽  
Mass Transfer Studies

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

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