Drying of Latex Backcoated Acrylic Fabrics: Heat Transfer Coefficients

1988 ◽  
Vol 58 (12) ◽  
pp. 681-688
Author(s):  
Douglas D. Jinks ◽  
Michael J. Matteson
Keyword(s):  
Heat Transfer ◽  
Mass Velocity ◽  
Packed Bed ◽  
Laboratory Scale ◽  
Packed Beds ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Through ◽  
Shaped Fibers

Drying and curing tests were performed in a laboratory scale dryer on dyed tufted acrylic fabrics and the latex adhesive backcoating to obtain heat transfer coefficients as a function of the mass velocity of air flowing through the fabric. Treating the fabric as a packed bed of cylindrically shaped fibers, equations were developed making it possible to calculate the flow-through velocity Gtf from measured air velocities directed at the upper and lower faces of the fabric. Correlations obtained for the heat transfer coefficients were h = 2.22 Gtf0.47 for fabric drying and h = 4.84 Gtf0.32 for curing the latex adhesive backcoating ( h in W/m2 K, Gtf in kg/m2h). These results were compared with earlier investigations of the drying in packed beds.

An Analytical Study of the Optimized Performance of an Impingement Heat Sink

2004 ◽  
Vol 126 (4) ◽  
pp. 528-534 ◽  
Author(s):  
S. B. Sathe ◽  
B. G. Sammakia
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
High Performance ◽  
Cross Flow ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Flow Through

The results of a study of a new and unique high-performance air-cooled impingement heat sink are presented. An extensive numerical investigation of the heat sink performance is conducted and is verified by experimental data. The study is relevant to cooling of high-power chips and modules in air-cooled environments and applies to workstations or mainframes. In the study, a rectangular jet impinges on a set of parallel fins and then turns into cross flow. The effects of the fin thickness, gap nozzle width and fin shape on the heat transfer and pressure drop are investigated. It is found that pressure drop is reduced by cutting the fins in the central impingement zone without sacrificing the heat transfer due to a reduction in the extent of the stagnant zone. A combination of fin thicknesses of the order of 0.5 mm and channel gaps of 0.8 mm with appropriate central cutout yielded heat transfer coefficients over 1500 W/m2 K at a pressure drop of less than 100 N/m2, as is typically available in high-end workstations. A detailed study of flow-through heat sinks subject to the same constraints as the impingement heat sink showed that the flow-through heat sink could not achieve the high heat transfer coefficients at a low pressure drop.

scholarly journals PARTICLE-STAGNANT FLUID HEAT TRANSFER COEFFICIENTS IN PACKED BEDS

1973 ◽  
Vol 6 (3) ◽  
pp. 269-270 ◽  
Author(s):  
NORIAKI WAKAO ◽  
YOSHINOBU TAKANO ◽  
D. G. T. PEI
Keyword(s):  
Heat Transfer ◽  
Packed Beds ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Stagnant Fluid

A Network-of-Voids Model to Assess Wall Flow Patterns and Heat Transfer for Low Aspect Ratio Packed-Bed Reactors

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter I Chigada ◽  
Reginald Mann
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Fluid Flows ◽  
Packed Bed ◽  
Wall Heat Transfer ◽  
Transfer Coefficients ◽  
Catalytic Reactors ◽  
Heat Transfer Coefficients ◽  
Low Aspect Ratio ◽  
Random Placement

Exothermic packed bed catalytic reactors are usually characterised by a low diameter-aspect ratio to facilitate heat transfer. In operation, these reactors often exhibit localized regions with much higher temperatures referred to as hot spots. A new model based on a 2-D network-of voids (NoV) has been devised to explore wall heat transfer behaviour for such low aspect ratio packed tubes. Random placement of (packing) particles is used to provide a simple NoV framework for implicitly creating the tortuous fluid flows amongst the resulting randomized inter-connecting voids. This is a computationally tractable strategy for exploring the haphazard appearance of individual tube pin-hole burn-outs amongst the typically thousands, or tens of thousands, of tubes within high temperature industrial multi-tubular configurations. Although presently limited to 2-D, the model captures many natural features of the flow and heat transfer of randomly packed tubes, especially huge variations in wall and cross flows and consequently massive variations in local wall heat transfer coefficients along the length of individual tubes. The model is potentially superior to those based upon averaged properties, which do not properly distinguish the solid and fluid phases. The network-of-voids concept is readily extended to 3-D, in order to achieve geometric congruence of the model and assemblies of individual particles.

New Approach to Determine the Heat+transfer Coefficients for Cooling Tower Packing

1989 ◽  
Vol 203 (2) ◽  
pp. 75-84 ◽  
Author(s):  
M A Younis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cooling Tower ◽  
Empirical Relationship ◽  
Packed Bed ◽  
Transfer Coefficients ◽  
Water Contact ◽  
Heat Transfer Coefficients ◽  
Tower Packing

The heat input response technique was developed to determine the heat-transfer coefficients for a forced draught cooling tower packing. The method was applied to a counter current type air-water contact system in a packed bed. A temperature change was alternately imposed on inlet air at the tower bottom and on inlet water at the tower top. Outlet temperatures of air and water were measured with time. From zeroth moments of these temperature changes, water-film and air-film heat-transfer coefficients have been estimated. Finally, the effect of the water/air loading ratio and the packing material, such as wood, aluminium wire netting and plastic PVC on the values of the heat-transfer coefficients was experimentally tested. An empirical relationship between the gas-side heat-transfer coefficient, liquid-side heat-transfer coefficient and water/gas ratio has been established within the range of the tested data.

Local and average interphase heat transfer coefficients in a randomly packed bed of spheres

AIChE Journal ◽  
1968 ◽  
Vol 14 (3) ◽  
pp. 483-490 ◽  
Author(s):  
Bernard M. Gillespie ◽  
Edward D. Crandall ◽  
James J. Carberry
Keyword(s):  
Heat Transfer ◽  
Packed Bed ◽  
Transfer Coefficients ◽  
Interphase Heat Transfer ◽  
Heat Transfer Coefficients
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