Related Papers
Journal of Heat Transfer
Latent Heat Fluxes Through Soft Materials With Microtruss Architectures
2008 •
Edwin Thomas
Microscale truss architectures provide high mechanical strength, light weight, and open porosity in polymer sheets. Liquid evaporation and transport of the resulting vapor through truss voids cool nearby surfaces. Thus, microtruss materials can simultaneously prevent mechanical and thermal damage. Assessment of promise requires quantitative understanding of vapor transport through microtruss pores for realistic heat loads and latent heat carriers. Pore size may complicate exegesis owing to vapor rarefaction or surface interactions. This paper quantifies the nonboiling evaporative cooling of a flat surface by water vapor transport through two different hydrophobic polymer membranes, 112–119μm (or 113–123μm) thick, with microtruss-like architectures, i.e., straight-through pores of average diameter of 1.0–1.4μm (or 12.6–14.2μm) and average overall porosity of 7.6% (or 9.9%). The surface, heated at 1350±20Wt∕m2 to mimic human thermal load in a desert (daytime solar plus metabolic), was...
Applied Physics Letters
Biologically inspired porous cooling membrane using arrayed-droplets evaporation
2010 •
Monika Jenko
Journal of Applied Mechanics
Editorial: Thermal Science and Engineering With Emphasis on Porous Media
2006 •
Dennis A . Siginer
ABSTRACT: This special issue of JAM brings together 16 selected papers from the First Conference on Thermal Engineering held in Beirut on May 31–June 4, 2004. I would like to express my gratitude to the Editor of JAM, Professor McMeeking, for dedicating a special issue of this prestigious journal to selected papers of the inaugural conference on Thermal Engineering. It has always been the tradition for scientists from the Middle East and the Gulf region, as well as North Africa, to conduct their graduate studies abroad, particularly in North America and Eu-rope. Governments in the region are committed to improving undergraduate education, but until recently it has been the norm not to focus so much on graduate education. Building research capability in institutions of higher learning and attracting highly motivated staff to advance the research agenda were not among the top priorities. But, higher education in this part of the world has started to change thanks to the foresight of the leaders in the region. However, the fact remains that highly-skilled scientists and engineers from the Middle East, the Gulf region, and North Africa sought and are still seeking work abroad in academic and research institutions.
Enhancing Heat Transfer from a Porous Plate with Transpiration Cooling
2017 •
Mustafa Kılıç
The present study is focused on developing structural solid surface geometry to improve heat transfer by cooling of air with transpiration cooling. Effects of flow rate of water ( ṁ water = 0.000083, 0.000116, 0.000166, 0.000249 kg/s) and particle diameter of porous plate (Dp= 40, 50, 100, 200 μ m) on local wall temperature and cooling efficiency of porous plate and the system inside a rectangular channel with air as a hot gas stream and water as a coolant were investigated experimentally. High performance polyethylene as a porous media was used not only to form a thermal barrier but also an active cooling plate by evaporating water from the surface of porous media to cool air. Temperatures were measured by T-type thermocouples. Two electric heaters were used to support enough power to the system. It was observed that increasing water flow rate did not cause a prominent decrease on surface temperature and cooling efficiency of porous plate. The higher injection rates result in furth...
Journal of Applied Mechanics
Thermal Science and Engineering With Emphasis on Porous Media
2006 •
Dennis A . Siginer
Volume 10: Heat and Mass Transport Processes, Parts A and B
Nanoporous Membrane Tube Condensing Heat Transfer Enhancement Study
2011 •
Cheng-xian Lin
A Transport Membrane Condenser (TMC), made from nanoporous membrane tube bundles, was developed by Gas Technology Institute (GTI) to recover the water vapor and its significant amount of latent heat from boiler flue gases to improve boiler efficiency and save water. Water vapor condensing phenomenon inside membrane pores is different in two aspects from surface condensation when the membrane pore size is in the nanometer scale. First, based on the pore capillary condensation mechanism—Kelvin equation, pore condensation can occur when local gas stream relative humidity is well below 100%, so more water condensation is possible at the same surface temperature compared with surface condensation. Second, as membrane heat exchanging surface continues evacuating condensed water to the permeate side, no water will be accumulated on the condensing surface, which eliminates the additional heat transfer resistance caused by the condensed liquid film (or droplets) for a conventional impermeabl...
Journal of Industrial Textiles
Effect of moisture condensation on vapour transmission through porous membranes
Ariana Kennedy
Porous membranes find natural application in various fields and industries. Water condensation on membranes can block pores, reduce vapour transmissibility, and diminish the porous membranes' performance. This research investigates the rate of water vapour transmission through microporous nylon and nanofibrous Gore-Tex membranes. Testing consisted of placing the membrane at the intersection of two chambers with varied initial humidity conditions. One compartment is initially set to a high ([Formula: see text]water vapour concentration and the other low ([Formula: see text], with changes in humidity recorded as a function of time. The impact of pore blockage was explored by pre-wetting the membranes with water or interposing glycerine onto the membrane pores before testing. Pore blockage was measured using image analysis for the nylon membrane. The mass flow rate of water vapour ( ṁv) diffusing through a porous membrane is proportional to both its area (A) and the difference in v...
Springer eBooks
Emerging topics in heat and mass transfer in porous media : from bioengineering and microelectronics to nanotechnology
2008 •
Peter Vadasz
Energy Procedia
CFD Characterization of Pressure Drop and Heat Transfer Inside Porous Substrates
2015 •
Gavin Tabor
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Porous materials for thermal management under extreme conditions
2006 •
Athina Markaki
A brief analysis is presented of how heat transfer takes place in porous materials of various types. The emphasis is on materials able to withstand extremes of temperature, gas pressure, irradiation, etc., i.e. metals and ceramics, rather than polymers. A primary aim is commonly to maximize either the thermal resistance (i.e. provide insulation) or the rate of thermal equilibration between the material and a fluid passing through it (i.e. to facilitate heat exchange). The main structural characteristics concern porosity (void content), anisotropy, pore connectivity and scale. The effect of scale is complex, since the permeability decreases as the structure is refined, but the interfacial area for fluid–solid heat exchange is, thereby, raised. The durability of the pore structure may also be an issue, with a possible disadvantage of finer scale structures being poor microstructural stability under service conditions. Finally, good mechanical properties may be required, since the deve...
