A Technique for Producing Drinking Water from Air Using Adsorbents Driven by Solar Energy：Theoretical and Experimental Research

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Three—Dimensional Heat Transfer Analysis for A Thermal Energy Storage Canister

IlltroductionSolar dynamic power modules (SDPM) with phasechange material (PCM) is a vital solution to ensureuninterrupted power supply for low-earth orbitapplication. The advantage of SDPM is its longerlifehme and higher efficiency. Longer lifetime results insubstanhal savings in hardware replacement, launch, andon-orbit installation costs. Because of SDPM's higherefficiency, its solar collection area is only about 25percent of that for a PV system. This would allowspacecraft operatin…     

Fuel Economy Opportunities for Internal COmbustion Engines by Means of Oil—Cooling

INTRODUCTIoNHeattransferbetweentheworkingmediuminare-ciprocatingengineanditscombustionchamberwallplaysaveryimportantroleintheenginethermalpro-cess.Alargeamountofheatsuppliedbythefuelislosttothecoolantthroughthecombustorwall.Thepercentagerangesfrom1o-25atfullloadto3ty35atlightloadcondition[11.Sincetheconceptofadi-abaticturbocompoundengineswaspresentedin1atel97o's[zl,worldwideattentionhasbeenattractedtotheopportunitiestoimprovethefuelconsumptionbyreducingtheheattransferratesthroughthecom-bus…     

Natural Convective Heat and Mass Transfer of Water with Corrosion Products at Super—Critical Pressures under Cooling COnditions

A numerical study is reported of laminar natural convective heat and mass transfer on a vertical cooled plate for water containing metal corrosion products at super-critical pressures. The influence of variable properties at super-critical pressures on natural convection has been analyzed. The difference between heat and mass transfer under cooling or heating conditions is also discussed and some correlations for heat and mass transfer under cooling conditions are recommended.     

Evaluation of Single Phase Flow in Microchannels for High Heat Flux Chip Cooling—Thermohydraulic Performance Enhancement and Fabrication Technology

The increased circuit density on today's computer chips is reaching the heat dissipation limits for air-cooling technology. The direct liquid cooling of chips is being considered as a viable alternative. This paper reviews liquid cooling with internal flow channels in terms of technological options and challenges. The possibilities presented herein indicate a four- to ten-fold increase in heat flux over the air-cooled systems. The roadmap for single-phase cooling technology is presented to identify research opportunities in meeting the cooling demands of future IC chips. The use of three-dimensional microchannels that incorporate either microstructures in the channel or grooves in the channel surfaces may lead to significant enhancements in single-phase cooling. A simplified and well-established fabrication process is described to fabricate both classes of three-dimensional microchannels. Proof-of-concept microchannels are presented to demonstrate the efficacy of the fabrication process in fabricating complex microstructures within a microchannel.     

Convective Heat and Mass Transfer in Water at Super—Critical Pressures under Heating or Cooling Conditions in Vertical Tubes

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DPL Model Analysis of Non—Fourier Heat Conduction Restricted by Continuous Boundary Interface

IntroductionAs widely known, the hahonal Fourier law isbased on a large quantity of regular heat transfer (i.e. thethermal bine scale is comparatively lOng and the heatflux density is comparatively small) experiments and it'sjust a phenomenological descriphon of regular thermalProcesses. The Fourier law itself mpes an infinitespeed of Propagation of thermal distUrbance, indicatingthat a local change in tempera~ causes aninstantaneous per'tUrbation in the temperatore at eachPOint in the medi…     

Study of the Thermal Behavior of Multi Tube Tank in Heat Recovery from Chimney—Analysis and Optimization

This work discusses the utilization of multi tube tank heat exchanger for waste heat recovery. The thermal behavior of the system is studied in order to understand the contribution of the different heat transfer modes governing the system. As application, heating water in residential application from chimney heat recovery is considered. A prototype illustrating the suggested system is implemented and tested. Different waste heat scenarios by varying the quantity of burned firewood (heat input) are experimented. The temperature at different parts of the system and the gas flow rates of the exhaust pipes are measured. Measurements showed that the temperature of 95 L tank of water can be increased by 68°C within one hour. Obtained results show that the convection and radiation exchanges at the bottom surface of the tank have a considerable impact on the total heat transfer rate of the water (as high as 70%). Moreover, the proposed system allows saving 9.8 L of gasoline, 10.6 L of diesel or 15 kg of wood for 12 hours of chimney operation.     

Heat transfer from a horizontal circular wire at small reynolds and grashof numbers—II: Mixed convection

Heat transfer from a horizontal fine cylinder by mixed, forced and free convection is investigated. Theoretical correlations of the heat transfer when forced or free convection at small Reynolds or Grashof numbers is affected by the other comparatively slight free or forced convection respectively, are given by the expansion method similar to the cases of pure convection described in Part I. The effects of the slight convection on the heat transfer are expressed systematically by a parameter of $\text{PrRe}{}^3\text{NuGr}$. Experimentally, the heat-transfer behavior under corresponding mixed convections was observed by moving a wire in air enclosed in a large box either vertically downward, vertically upward or horizontally. The agreement between analyses and experiments is satisfactory especially in parallel flow.     

Heat transfer from a horizontal circular wire at small reynolds and grashof numbers—I: Pure convection

Heat transfer from a horizontal fine cylinder by pure forced convection at small Reynolds numbers or by pure free convection at small Grashof numbers is analyzed without restriction on Prandtl number by the method of joining the circumferential average temperature in the concentric layer around the cylinder governed mainly by conduction to that in the wake or plume governed mainly by convection. The agreement between analysis and experiment is satisfactory.     

Solar photocatalytic removal of herbicides from real water by using sol–gel synthesized nanocrystalline TiO2: Operational parameters optimization and toxicity studies

A comparative study of the photocatalytic activity of two different TiO₂ catalysts in solar photocatalytic oxidation, mineralization and detoxification of waters containing herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), bentazon and toxic intermediates was performed in a pilot plant scale photoreactor. Commercial TiO₂ (Degussa P25) and TiO₂ synthesized by citrate sol–gel method (ECT-1023t) were selected as photocatalysts. The optimal basic operational parameters to eliminate these herbicides and toxic intermediates were established for both catalysts at laboratory scale. ECT-1023t showed better photocatalytic activity than the commercial Degussa P25 at solar pilot plant scale with both herbicides in real water at natural pH (6.8–7.8) without any additive. The toxicity of the treated solutions was evaluated using the Microtox test based on the inhibition of bioluminescence of the bacteria Vibrio fischeri. The toxic effect of the main intermediate of 2,4-D, the 2,4-dichlorophenol (2,4-DCP), was higher than the parental herbicide. Acute toxicity of 2,4-D and intermediates (2,4-DCP) was reduced during the photocatalytic treatment by using ECT-1023t as photocatalyst. Longer times were necessary to obtain similar results when using P25 as photocatalyst. No inhibitory growth effect of the herbicide bentazon and its photoproducts on Vibrio fischeri bacteria bioluminescence was observed for either photocatalyst in any of the irradiated samples collected at predetermined times using an initial concentration of 0.1325 mM of the herbicide.     

Lowering Dislocation Density of Directionally Grown Multicrystalline Silicon Ingots for Solar Cells by Simplifying Their Post-Solidification Processes—A Simulation Approach

A simplified post-solidification process for industrial production of directionally grown multicrystalline silicon ingot is proposed, in which the bottom temperature of the ingot decreases together with the top temperature, omitting the rising stage in the conventional process. Three-dimensional numerical simulations with the HAS model of dislocation multiplication have been carried out to analyze their stresses and dislocation densities. The results show that the stress and dislocation density in silicon ingot with the proposed process are greatly lower than those from the conventional process. Moreover, the proposed process can reduce the processing cost.     

Solar collectors versus lamps—a comparison of the energy demand of industrial photochemical processes as exemplified by the production of ε-caprolactam

The energy demand of photochemical synthesis of ε-caprolactam was compared for two plant concepts. The conventional lamp-driven concept followed the process as realized on an industrial scale by Toray Ltd, Japan and a solar concept was designed at identical yearly output. The aim of the comparison was to determine the savings of fossil fuels that could be achieved if photochemistry could make use of solar radiation instead of artificial light. The use of solar radiation for the photochemical production of ε-caprolactam has a 4-fold lower demand for electric current and an 8-fold lower demand for cooling energy as compared to an equivalent conventionally operated route. Furthermore, due to avoided conversion of fossil fuel to electric current, a solar process would allow specific emissions of 1.5–2.5 tons of CO₂ per ton ε-caprolactam to be avoided, depending on the primary energy carrier used.     

Thermal Conductivity Measurement of Semitransparent Media at Temperatures from 300 to 800 K by Hot—Wire Method

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