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The present work is to investigate nucleate boiling heat transfer at high heat fluxes, which is characterized by the existence of macrolayer. Two‐region equations are proposed to simulate both thermo‐capillary driven flow in the liquid layer and heat conduction in the solid wall. The numerical simulation results can clearly describe the activities of several multi vorticies in the macrolayer. These vorticies and evaporation at the vapor‐liquid interface constitute a very efficient heat transfer mechanism to explain the high heat transfer coefficient of nucleate boiling heat transfer near CHF. This study also explores the flow pattern of macrolayer with a high conducting solid wall, e.g. copper, and hence the temperature is uniform at the liquid‐solid interface, and the heat fluxes and the evaporation coefficient are found to have significant effect on flow pattern in the liquid layer. Furthermore, a parameter “evaporation fraction” as well as “aspect ratio” is proposed as an index to investigate the thermo‐capillary driven flow system. The model prediction agrees reasonably well with the experimental data in the literature.

The water evaporation rate (WER) is not only crucial for fabric drying, but also an important parameter affecting cooling from a body wearing sweat wetted clothing. The purpose of this paper is to predict the WERs of wet textile materials in a pre-defined environment.

The maximum water evaporation rate (WER_max) from a saturated surface in a pre-defined environment was first predicted based on the Lewis relationship between the evaporative and the convective heat transfer in this paper. The prediction results were validated by the comparisons with experimental measurements in various environments obtained in this paper and reported in the literature.

Experiment results show that the ratios of WERs to WER_max are lower than 100 percent but higher than 50 percent, which confirmed that the prediction of WER_max is reliable. The temperature decrease of the wet material surface due to evaporation was considered to account for the difference between measured WERs and the WERmax, and the WER variation among materials. The lower ratios of WERs to WER_max in the higher wind condition were speculated to be due to the greater temperature decrease caused by the increased evaporation.

It provides a reliable way to obtain both WER_max and WER (WER_max multiplied by a proper ratio), which can be useful in clothing physiological modeling to predict clothing comfort.

This study contributes to the understanding of the evaporation process of textile materials.

This paper aims to introduce a two-dimensional smoothed particle hydrodynamics (SPH) framework for simulating the evaporation and combustion process of fuel droplets.

To solve the gas–liquid two-phase flow problem, a multiphase SPH method capable of handling high density-ratio problems is established. Based on the Fourier heat conduction equation and Fick’s law of diffusion, the SPH discrete equations are derived. To effectively characterize the phase transition problem, inspired by volume of fluid method, the concept of liquid phase mass fraction of the SPH particles is proposed. The one-step global reaction model of n-hexane is used for the vapor combustion.

The evaporation and combustion process of single droplet conforms to the law. The framework works out well when the evaporation of multiple droplets involves coalescence process. Three different kinds of flames are observed in succession in the combustion process of a single droplet at different inflow velocity, which agree well with the results of the experiment.

To the best of the authors’ knowledge, this is the first computational framework that has the capability to simulate evaporation and combustion with SPH method. Based on the particle nature of SPH method, the framework has natural advantages in interface tracking.

In most ball bearings, grease functions primarily as a storehouse for the small amount of oil needed to coat ball, raceway and separator surfaces. Bearing life tests indicate that as a grease ages in service, it finally dries to a degree where it fails to provide this lubrication demand when about half the original oil is gone. This condition of dryness which leads to failure is also related to operating factors such as bearing temperature, speed and load.

The present study aims to investigate the inverse-thermocapillary effect in an evaporating thin liquid film of self-rewetting fluid, which is a dilute aqueous solution (DAS) of long-chain alcohol.

A long-wave evolution model modified for self-rewetting fluids is used to study the inverse thermocapillary characteristics of an evaporating thin liquid film. The flow attributed to the inverse thermocapillary action is manifested through the streamline plots and the evaporative heat transfer characteristics are quantified and analyzed.

The thermocapillary flow induced by the negative surface tension gradient drives the liquid from a low-surface-tension (high temperature) region to a high-surface-tension (low temperature) region, retarding the liquid circulation and the evaporation strength. The positive surface tension gradients of self-rewetting fluids induce inverse-thermocapillary flow. The results of different working fluids, namely, water, heptanol and DAS of heptanol, are examined and compared. The thermocapillary characteristic of a working fluid is significantly affected by the sign of the surface tension gradient and the inverse effect is profound at a high excess temperature. The inverse thermocapillary effect significantly enhances evaporation rates.

The current investigation on the inverse thermocapillary effect in a self-rewetting evaporating thin film liquid has not been attempted previously. This study provides insights on the hydrodynamic and thermal characteristics of thermocapillary evaporation of self-rewetting liquid, which give rise to significant thermal enhancement of the microscale phase-change heat transfer devices.

Salt weathering is one of the most common agents of decay of Central Asian earthen sites and is in function of water evaporation from the wall surface. Soon after excavation the earthen walls and the stupa of the Buddhist temple of Ajina Tepa (seventh-eighth century AD) started to deteriorate due lack of protection and surface erosion. The most important issue in the planning of conservation work was to understand such mechanisms and to decrease the effect of salt weathering on structural damage. The purpose of this paper is to discuss these issues.

Evaporation distribution and salts types were studied on selected walls. In addition, three-dimensional recording of the walls and the stupa was undertaken with digital photogrammetric methods.

It was clearly found that the intensity of salt weathering in the site is high and some salts such as halite (sodium chloride) are thought to originate from groundwater. On the basis of the results obtained, thick shelter coating with mud brick and mud render was designed and constructed as protective measure for the earthen walls.

Those walls that were most affected by salts weathering and erosion at the base (coving) became structurally less sound and eventually collapsed if not conserved.

The work is the first attempt in the design of a methodology for the selection of earthen repair materials and methods.

A computational model is developed to describe convection in volatile liquids evaporating in capillary tubes. Experimental work has demonstrated the existence of such convective structures. The correlation between this convection and the phase change process has been experimentally established. Temperature distribution on the liquid‐vapour interface is considered in order to characterise the minimum of radial temperature gradient required to initiate and orientate Marangoni convection. Direct numerical simulation using finite volume approximation is used to investigate the heat and mass transfer in the liquid phase. The case of a capillary tube filled with a volatile liquid is investigated for various Marangoni numbers, to characterise heat and mass transfers under conditions close to realistic operating parameters. The simulation shows that a minimum irregularity in evaporative flux along the liquid‐vapour interface is necessary to trigger thermocapillary convection. The enhancement of heat and mass transfer by Marangoni convection is also investigated.

Rising damp affects the deterioration and conservation of architectural heritage. Air cavities built next to the base of these buildings on an unsaturated floor can reduce the damage to foundations and walls due to this. These are passive systems, which are usually designed with no objective data to show their functioning and effectiveness. This is why the authors are presenting this study.

This study is presented starting with simple field equipment for representative types for a previous cataloguing of cases in Spain. The physical parameters of the air in this research are air speed and evaporation in the cavities and the base, taking the local climate and the particular formal and construction characteristics of each case study as a reference.

The results of the analysis validate the method and the efficiency of such cavities, whose performance is greater in systems with a variety of features, that is to say, those which work by thermal or wind flow rather than those which only use hygric flow.

This work is novel because there are not in situ experimental works which prove the functioning and effectiveness of these systems.

The main objective of this paper is the assessment of the environmental impact due to accidental spills of toxic and flammable liquids on land. Different case studies of possible accidents in the State of Qatar were considered. An EPA‐based dispersion model was utilized to estimate the size and location of the dangerous clouds generated by such spills at different elapsed times. Three case studies of possible accidents in the State of Qatar involving gasoline were considered. Due to the transient nature of the dispersion processes in the case studies, the results showed clearly the phenomenon of growth and decay of the generated dangerous clouds. An interface between the dynamic results of the dispersion software and the static data of the Qatar geographical information system (GIS) allowed the immediate identification of the major landmarks affected by the considered accidents. These data would be of great help in developing an emergency evacuation plan for such accidents.

The aim of this work is to investigate the decomposition behaviour of the activator species commonly used in the wave solder no-clean flux systems and to estimate the residue amount left after subjecting the samples to simulated wave soldering conditions.

Changes in the chemical structure of the activators were studied using Fourier transform infrared spectroscopy technique and were correlated to the exposure temperatures within the range of wave soldering process. The amount of residue left on the surface was estimated using standardized acid-base titration method as a function of temperature, time of exposure and the substrate material used.

The study shows that there is a possibility of anhydride-like species formation during the thermal treatment of fluxes containing weak organic acids (WOAs) as activators (succinic and DL-malic). The decomposition patterns of solder flux activators depend on their chemical nature, time of heat exposure and substrate materials. Evaporation of the residue from the surface of different materials (laminate with solder mask, copper surface or glass surface) was found to be more pronounced for succinic-based solutions at highest test temperatures than for adipic acid. Less left residue was found on the laminate surface with solder mask (∼5-20 per cent of initial amount at 350°C) and poorest acid evaporation was noted for glass substrates (∼15-90 per cent).

The findings are attributed to the chemistry of WOAs typically used as solder flux activators. The results show the importance WOA type in relation to its melting/boiling points and the impact on the residual amount of contamination left after soldering process.

The results show that the evaporation of the flux residues takes place only at significantly high temperatures and longer exposure times are needed compared to the temperature range used for the wave soldering process. The extended time of thermal treatment and careful choice of fluxing technology would ensure obtaining more climatically reliable product.