Steam impinging and heat and water spreading in fabrics

2018 ◽  
Vol 89 (8) ◽  
pp. 1455-1471 ◽  
Author(s):  
Shuaitong Liang ◽  
Ning Pan ◽  
Yuexin Cui ◽  
Xiongying Wu ◽  
Xuemei Ding
Keyword(s):  
Heat Transfer ◽  
Water Flow ◽  
Theoretical Approach ◽  
Water Movement ◽  
Heat And Mass Transport ◽  
Inherent Anisotropy ◽  
Flow Processes ◽  
Theoretical Predictions ◽  
The Mean ◽  
Water Spreading

This study is about the heat and mass transport phenomena in a system with steam jet flow to eliminate/alleviate cloth wrinkles. We first adopted a theoretical approach to derive the mean capillary radii so that a fabric can be characterized as an assembly of capillary tubes with varying diameters. We then analyzed the processes as a heat transfer via the fibers and water via the pores in fabrics of different anisotropies. During water movement, the water weight actually intensifies the inherent anisotropy of the fabric in the water flow pattern. For heat transfer, the water weight becomes irrelevant and both convection and radiation are shown to be too trivial to include. Corresponding experiments are also conducted, using infrared and visible light cameras to record the heat and water flow processes, respectively. The results are compared with the theoretical predictions and the discrepancies are explored and explained.

A preliminary exploration of the micro-scale behaviour of capillary barrier effect using microfluidics

Géotechnique ◽  
2021 ◽  
pp. 1-25
Author(s):  
Liang-Tong Zhan ◽  
Guang-Yao Li ◽  
Bate Bate ◽  
Yun-Min Chen
Keyword(s):  
Porous Media ◽  
Water Flow ◽  
Water Movement ◽  
Barrier Effect ◽  
Capillary Barrier ◽  
Micro Scale ◽  
Flow Processes ◽  
Basic Physics ◽  
Throat Width ◽  
Coarse Porous Media

Capillary barrier effect (CBE) is employed in a large number of geotechnical applications to decrease deep percolation or increase slope stability. However, the micro-scale behaviour of CBE is rarely investigated, and thus hampers the scientific design of capillary barrier systems. This study uses microfluidics to explore the micro-scale behaviour of CBE. Capillarity-driven water flow processes from fine to coarse porous media with different pore topologies and sizes were performed and analysed. The experimental results demonstrate that the basic physics of CBE is the preferential water movement into the fine porous media due to the larger capillarity. The effects of CBE on water flow processes can be identified as delaying the occurrence of breakthrough into the coarse porous media and increasing the water storage of the fine porous media. The CBE can impede the increase of the normalized length and decrease the normalized width of the water front, suggesting that the two normalized parameters are potential indicators to assess the performance of CBE at micro scale. CBE can be formed in square and honeycomb networks with the ratio of coarse to fine pore throat width larger than 2.0 when gravity is neglected, and its performance can be affected by pore topology and size.

Convective movement of Ca2+ across guinea pig gallbladder epithelium

1992 ◽  
Vol 262 (6) ◽  
pp. G990-G995
Author(s):  
R. V. Rege ◽  
E. W. Moore
Keyword(s):  
Guinea Pig ◽  
Water Flow ◽  
Water Movement ◽  
Therapeutic Modality ◽  
Gallbladder Epithelium ◽  
Sieving Coefficient ◽  
The Mean ◽  
Convective Movement ◽  
Made In

Recently, much interest has developed in biliary calcium because of its importance in the pathogenesis and composition of gallstones. While much progress has been made in understanding the thermodynamic factors that control biliary calcium concentrations, little is known about the kinetic factors that control the movement of calcium across the gallbladder epithelium. These studies measure guinea pig gallbladder epithelial permeability to Ca2+ during in vivo convective water movement across the membrane. Water movement, ranging from -15.2 (absorption) to 6.3 microliters.min-1.cm-2 (water entry), was induced by placing hypotonic, isotonic, and hypertonic solutions into the gallbladder lumen. Calcium movement was found to be directly and linearly related to water flow, indicating that Ca2+ moved with the convective water flow, presumably across paracellular channels. The slope of this relationship (0.602), representing the concentration of calcium in the fluid translocated across the gallbladder epithelium, was only about half that of plasma or luminal contents, indicating that calcium movement across the membrane was restricted. The mean sieving coefficient (1 - r) of guinea pig gallbladder, calculated from this slope, was approximately 0.5, indicating that the epithelium is only moderately permeable to Ca2+. The results suggest that intraluminal chelation of Ca2+ for the possible prevention and/or treatment of calcium-containing gallstones is a potentially feasible therapeutic modality.

HEAT TRANSFER BURNOUT IN WATER FLOW THROUGH ROUND TUBES AND ANNULI

1970 ◽  
Author(s):  
B. A. Zenkevich ◽  
P. L. Kirillov ◽  
G. V. Alekseev ◽  
O. L. Peskov ◽  
O. A. Sudnitsyn
Keyword(s):  
Heat Transfer ◽  
Water Flow ◽  
Flow Through

Experimental Study on Thermal Characteristics of Finned Coil LHSU Using Paraffin as Phase Change Material

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Guansheng Chen ◽  
Nanshuo Li ◽  
Huanhuan Xiang ◽  
Fan Li
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Phase Change ◽  
Phase Change Material ◽  
Water Flow ◽  
Water Flow Rate ◽  
Thermal Characteristics ◽  
Heat Transfer Fluid ◽  
Latent Heat Storage ◽  
Change Material

It is well known that attaching fins on the tubes surfaces can enhance the heat transfer into and out from the phase change materials (PCMs). This paper presents the results of an experimental study on the thermal characteristics of finned coil latent heat storage unit (LHSU) using paraffin as the phase change material (PCM). The paraffin LHSU is a rectangular cube consists of continuous horizontal multibended tubes attached vertical fins at the pitches of 2.5, 5.0, and 7.5 mm that creates the heat transfer surface. The shell side along with the space around the tubes and fins is filled with the material RT54 allocated to store energy of water, which flows inside the tubes as heat transfer fluid (HTF). The measurement is carried out under four different water flow rates: 1.01, 1.30, 1.50, and 1.70 L/min in the charging and discharging process, respectively. The temperature of paraffin and water, charging and discharging wattage, and heat transfer coefficient are plotted in relation to the working time and water flow rate.

scholarly journals Effects of Temperature on the Flow and Heat Transfer in Gel Fuels: A Numerical Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 821
Author(s):  
Qin-Liu Cao ◽  
Wei-Tao Wu ◽  
Wen-He Liao ◽  
Feng Feng ◽  
Mehrdad Massoudi
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Transport System ◽  
Apparent Viscosity ◽  
Thermal Design ◽  
Straight Pipe ◽  
Heating Wall ◽  
Supply Pressure ◽  
Flow And Heat Transfer ◽  
The Mean

In general, rheological properties of gelled fuels change dramatically when temperature changes. In this work, we investigate flow and heat transfer of water-gel in a straight pipe and a tapered injector for non-isothermal conditions, which mimic the situations when gelled fuels are used in propulsion systems. The gel-fluid is modeled as a non-Newtonian fluid, where the viscosity depends on the shear rate and the temperature; a correlation fitted with experimental data is used. For the fully developed flow in a straight pipe with heating, the mean apparent viscosity at the cross section when the temperature is high is only 44% of the case with low temperature; this indicates that it is feasible to control the viscosity of gel fuel by proper thermal design of pipes. For the flow in the typical tapered injector, larger temperature gradients along the radial direction results in a more obvious plug flow; that is, when the fuel is heated the viscosity near the wall is significantly reduced, but the effect is not obvious in the area far away from the wall. Therefore, for the case of the tapered injector, as the temperature of the heating wall increases, the mean apparent viscosity at the outlet decreases first and increases then due to the high viscosity plug formed near the channel center, which encourages further proper design of the injector in future. Furthermore, the layer of low viscosity near the walls plays a role similar to lubrication, thus the supply pressure of the transport system is significantly reduced; the pressure drop for high temperature is only 62% of that of low temperature. It should be noticed that for a propellent system the heating source is almost free; therefore, by introducing a proper thermal design of the transport system, the viscosity of the gelled fuel can be greatly reduced, thus reducing the power input to the supply pressure at a lower cost.

Mean Temperature Difference Charts for Air Coolers

1983 ◽  
Vol 105 (3) ◽  
pp. 592-597 ◽  
Author(s):  
A. Pignotti ◽  
G. O. Cordero
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Temperature Difference ◽  
Optimization Technique ◽  
Independent Variables ◽  
Mean Temperature ◽  
Air Cooler ◽  
The Mean ◽  
The One ◽  
Water Ratio

Computer generated graphs are presented for the mean temperature difference in typical air cooler configurations, covering the combinations of numbers of passes and rows per pass of industrial interest. Two sets of independent variables are included in the graphs: the conventional one (heat capacity water ratio and cold fluid effectiveness), and the one required in an optimization technique of widespread use (hot fluid effectiveness and the number of heat transfer units). Flow arrangements with side-by-side and over-and-under passes, frequently found in actual practice, are discussed through examples.

Effects of Pin Shape and Array Orientation on Heat Transfer and Pressure Loss in Pin Fin Arrays

1984 ◽  
Vol 106 (1) ◽  
pp. 252-257 ◽  
Author(s):  
D. E. Metzger ◽  
C. S. Fan ◽  
S. W. Haley
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Pressure Loss ◽  
Flow Direction ◽  
Circular Cross Section ◽  
Cycle Performance ◽  
Mean Flow ◽  
Pin Fin ◽  
The Mean ◽  
Cooling Air

Modern high-performance gas turbine engines operate at high turbine inlet temperatures and require internal convection cooling of many of the components exposed to the hot gas flow. Cooling air is supplied from the engine compressor at a cost to cycle performance and a design goal is to provide necessary cooling with the minimum required cooling air flow. In conjunction with this objective, two families of pin fin array geometries which have potential for improving airfoil internal cooling performance were studied experimentally. One family utilizes pins of a circular cross section with various orientations of the array with respect to the mean flow direction. The second family utilizes pins with an oblong cross section with various pin orientations with respect to the mean flow direction. Both heat transfer and pressure loss characteristics are presented. The results indicate that the use of circular pins with array orientation between staggered and inline can in some cases increase heat transfer while decreasing pressure loss. The use of elongated pins increases heat transfer, but at a high cost of increased pressure loss. In conjunction with the present measurements, previously published results were reexamined in order to estimate the magnitude of heat transfer coefficients on the pin surfaces relative to those of the endwall surfaces. The estimate indicates that the pin surface coefficients are approximately double the endwall values.

Heat Transfer and Flowfield Measurements in the Leading Edge Region of a Stator Vane Endwall

1999 ◽  
Vol 121 (3) ◽  
pp. 558-568 ◽  
Author(s):  
M. B. Kang ◽  
A. Kohli ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Edge Region ◽  
Leading Edge Vortex ◽  
Stator Vane ◽  
Edge Vortex ◽  
The Mean

The leading edge region of a first-stage stator vane experiences high heat transfer rates, especially near the endwall, making it very important to get a better understanding of the formation of the leading edge vortex. In order to improve numerical predictions of the complex endwall flow, benchmark quality experimental data are required. To this purpose, this study documents the endwall heat transfer and static pressure coefficient distribution of a modern stator vane for two different exit Reynolds numbers (Reex = 6 × 105 and 1.2 × 106). In addition, laser-Doppler velocimeter measurements of all three components of the mean and fluctuating velocities are presented for a plane in the leading edge region. Results indicate that the endwall heat transfer, pressure distribution, and flowfield characteristics change with Reynolds number. The endwall pressure distributions show that lower pressure coefficients occur at higher Reynolds numbers due to secondary flows. The stronger secondary flows cause enhanced heat transfer near the trailing edge of the vane at the higher Reynolds number. On the other hand, the mean velocity, turbulent kinetic energy, and vorticity results indicate that leading edge vortex is stronger and more turbulent at the lower Reynolds number. The Reynolds number also has an effect on the location of the separation point, which moves closer to the stator vane at lower Reynolds numbers.

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