Condensation

A sulfuric acid aerosol model has been implemented in the global general circulation model ECHAM4. This model treats the formation, the development, and the transport of stratospheric sulfuric acid aerosol. The aerosol size distribution and the sulfuric acid mass fraction are calculated as a function of the H•SO4/H•O concentration, temperature, and air pressure in a size range between 0.001 and 2.58 •m. Binary homogeneous nucleation of H•SO4/H20, condensation and evaporation of H2SO4 and H20, Brownian coagulation and gravitational sedimentation are included. The microphysical model for stratospheric sulfate aerosol and a stratospheric sulfur chemistry are combined with a representation of the tropospheric sulfur chemistry. This tropospheric scheme accounts for the natural and anthropogenic emissions, chemistry, and dry and wet deposition of DMS, SO2, and SO•-. Globally and seasonally different SO2-and SO•-sources for stratospheric aerosol can therefore be taken into account. Results of a multiannual simulation show that the simulated SO2 and H2SO4 concentrations are generally in good agreement with available observations. The formation of new particles through homogeneous nucleation takes place in the tropical lower stratosphere and upper troposphere and in polar spring. The aerosol surface area density and the aerosol mass concentration reproduce lower stratospheric background conditions quite well. Effective radius and aerosol mixing ratio agree also with satellite and in situ measurements at Northern Hemisphere midlatitudes. 1. Introduction Stratospheric aerosol has various effects on the global climate system. It changes the chemical composition of the stratosphere because of heterogeneous reactions [Holmann and Solomon, 1989], provides condensation nuclei for the formation of polar stratospheric clouds and cirrus, and disturbs the radiative balance of the atmosphere in changing the albedo [Lacis et al., 1992]. These different atmospheric mechanisms are especially strong when the aerosol background layer is perturbed in response to strong volcanic eruptions or possibly in the future to high-speed civil transport aircraft. After the eruption of Mount Pinatubo (15.1øN, 120.4øE) in June 1991 a temperature increase in the lower stratosphere of •-2-3 K [Labitzke and McCormick, 1992] and a cooling of the global lower troposphere and the Earth's surface of • 0.5 K were detected [Dutton and Christy, 1992]. Furthermore, in 1992 and 1993 unusually strong ozone depletion due to chemical and dynamical processes was observed [Grant et al., 1994; Her-; Randel et al., 1995]. Stratospheric aerosol consists mainly of supercooled hydrated H2SO4 particles with a sulfuric acid mass fraction in the range of 50-80%. The particles form a persistent aerosol layer (Junge layer), which extends from the tropopause up to 30 km altitude. Height and maximum of the layer are seasonally and latitudinally dependent [Yue and Deepak, 1984]. The stratospheric aerosol particles are either directly formed in the stratosphere because of homogeneous nucleation or transported through the tropopause. In order to better understand the role of stratospheric aerosol in the atmospheric system several aerosol models were developed. At the end of the seventies, [ Turco et al., [1979] and [Turco et al., [1979] developed a one-dimensional (l-D) model, which was later refined by Toon et al. [1988] and Zhao et al. [1995]. Recently, Kgircher [1998] developed a coupled microphysical-chemical-dynamical box trajectory model for aircraft-generated liquid aerosols, which could also be applied to liquid H2SO4/HNOs/H•O aerosols. In the last years several studies with two-dimensional (2-D) chemistry transport models including sulfate aerosol microphysics were published in the literature. Theses studies focus on the impact of either aircraft emis-

Reported herein are the results of the experimental investigations on the eect of small amounts of heat transfer additives C add < 1000 ppm on steam condensation in a bundle of horizontal tubes that are internally cooled. The condenser was designed with 12 tubes in an array of three horizontals and four verticals with a 2-in. horizontal and 1.5-in. vertical in-line pitch. By using eective additives, the condensation heat transfer rate can be augmented as much as 30% as compared with heat transfer that operated without additives under the same operating condition. The steam condensation, which occurred in our experiments while using eective additives, was mostly dropwise like. When heat transfer additives function eectively, the condensate-droplets become more dispersed and have a smaller shape than those produced without additives. These droplets, unlike traditional turbulence, start at the top portion of the condenser tubes and cover most of the tubes. Such a¯ow behavior can be explained by the Marangoni eect (in terms of thermodynamic equilibrium) in connection with obtained surface tension data. Furthermore, we extend our discussion to the dynamic eect of surface tension in the steam condensation process and propose a general criterion for selecting eective additives. In our experiments, we noted that the use of heat transfer additives such as 2-ethyl-1-hexanol for steam condensation was highly eective.

A key parameter that controls the crystallization of primordial oceans in large icy moons is the presence of antifreeze compounds, which may have maintained primordial oceans over the age of the solar system. Here we investigate the influence of methanol, a possible anti-freeze candidate, on the crystallization of Titan's primordial ocean. Using a thermodynamic model of the solar nebula and assuming a plausible composition of its initial gas phase, we first calculate the condensation sequence of ices in Saturn's feeding zone, and show that in Titan's building blocks methanol can have a mass fraction of ∼4 wt% relative to water, i.e., methanol can be up to four times more abundant than ammonia. We then combine available data on the phase diagram of the water-methanol system and scaling laws derived from thermal convection to estimate the influence of methanol on the dynamics of the outer ice I shell and on the heat transfer through this layer. For a fraction of methanol consistent with the building blocks composition we determined, the vigor of convection in the ice I shell is strongly reduced. The effect of 5 wt% methanol is equivalent to that of 3 wt% ammonia. Thus, if methanol is present in the primordial ocean of Titan, the crystallization may stop, and a sub-surface ocean may be maintained between the ice I and high-pressure ice layers. A preliminary estimate indicates that the presence of 4 wt% methanol and 1 wt% ammonia may result in an ocean of thickness at least 90 km.

: A sounding climatology of a variety of parameters commonly used to forecast deep, moist convection using upper-air observations is developed. The data set includes 0000 and 1200 UTC rawinsonde data (approximately 3629 soundings) from Laughlin AFB, TX from April September 1995 2004. Cloud-to-ground lightning data, surface observations, and severe weather reports from the Storm Prediction Center (SPC) SeverePlot2 Program were used to categorize soundings as representative of conditions for no convection, light convection, convection within vicinity, moderate severe convection, or severe convection. Indices, including convective available potential energy (CAPE) and mean layer CAPE (MLCAPE), along with sounding parameters and combinations of such as 0-2 and 0-6 km bulk shear, 700-500 mb lapse rate, lifted condensation level (LCL) and mean layer LCL (MLLCL) heights, are examined in an attempt to distinguish between moderate and severe convection. The results show that the 0-6 km bulk ...

The collection efficiency of a fiber filter of polyester operating in the removal of nano-sized aerosols was studied here. The polyester filter utilized had 0.882 in porosity, 4.5 mm in thickness, and fiber mean diameter of 16.0 m. A TSI Electrospray Aerosol Generator, model 3480, was used to generate monodispersed nanometric particles, with sizes varying from 8.5 to 94.8 nm. The nanoparticles were generated from solutions of NaCl which were atomized as droplets, followed by drying. The filtration device was built in acrylic with a filtration area of 0.4 m 2 . The filter efficiencies were obtained by counting the particles before and after the filter, using a TSI Condensation Particle Counter, model 3007. The tests were accomplished at gas superficial velocities varying from 0.03 to 0.25 m/s. The results show the efficiency decreasing with increasing particle size, indicating the predominance of the diffusional mechanism in the range studied. Also, the filter efficiency decreased with filtration velocity. The results were compared to well known theoretical predictions based on the classical collection mechanisms: diffusional and direct interception. The comparison of the calculated collector efficiency with the experimental results showed that the predictions underestimate the results. A correction was proposed to the existing correlation for direct interception, where an 'effective' diameter accounting for the Brownian motion of the particle while in the vicinity of the collector surface was accounted for. The proposed modification included no fitting parameter. The results showed a considerable improvement in the prediction correlation.

The new AP600 reactor designed by Westinghouse uses a passive safety system relying on heat removal by condensation to keep the containment within the design limits of pressure and temperature. Even though some research has been done so far in this regard, there are some uncertainties concerning the behavior of the system under postulated accident conditions. In this paper, steam condensation onto the internal surfaces of the AP600 containment walls has been investigated in two scaled vessels with similar aspect ratios to the actual AP600. The heat transfer degradation in the presence of noncondensable gas has been analyzed for different noncondensable mixtures of air and helium (hydrogen simulant). Molar fractions of noncondensables/steam ranged from (0.4-4.0) and helium concentrations in the noncondensable mixture were 0-50% by volume. In addition, the effects of the bulk temperatures, the mass fraction of noncondensable/steam, the cold wall surface temperature, the pressure, noncondensable composition, and the inclination of the condensing surface were studied. It was found that the heat transfer coefficients ranged from 50 to 800 J s − 1 K − 1 m − 2 with the highest for high wall temperatures at high pressure and low noncondensable molar fractions. The effect of a light gas (helium) in the noncondensable mixture were found to be negligible for concentrations less than approximately 35 molar percent but could result in stratification at higher concentrations. The complete study gives a large and relatively complete data base on condensation within a scaled AP600 containment structure, providing an invaluable set of data against which to validate models. In addition, specific areas requiring further investigation are summarized.

This review describes the composition, preparation and applications in organic synthesis of polyphosphoric acid trimethylsilylester (PPSE). It covers the literature since it first appeared in the eighties until the first trimester of 2007. A discussion of the synthetic utility of PPSE, compared to other related reagents such as polyphosphoric acid (PPA) and polyphosphoric acid ethyl ester (PPE) as well as various Lewis acids, is also included.

Dynamical aspects of the life cycle of the winter storm 'Lothar' (24-26 December 1999) are investigated with the aid of the European Centre for Medium-Range Weather Forecasts analysis data and mesoscale model simulations. Neither of these datasets capture the full amplitude of the observed extreme pressure fall and surface wind speeds, but they do help identify a range of key dynamical and physical features that characterize the development of this unusual event. The analysis and interpretation is primarily based upon the evolution of the lower-and upper-level potential vorticity (PV) eld complemented by three-dimensional trajectory calculations.

This article presents an experimental investigation of heat transfer and pressure drop characteristics of R-134a condensing inside a horizontal helical coil tube with the cooling water flowing in the shell in counter flow direction. The test runs are performed at vapor saturation temperature 35 ± 0.5 and 40 ± 0.5°C for the mass flux varying from 100 to 350 kg m À2 s À1 and vapor quality ranging from 0.1 to 0.9. The flow regimes observed during the experiment have been plotted on Taitel and Dukler and mass flux versus vapor quality flow map. The transitions between different flow regimes have also been discussed. The effect of mass flux, vapor quality and saturation temperature on the heat transfer coefficient and pressure drop have been investigated. The experimental results of the helical coil tube are compared to straight tube. The thermodynamic advantage of helical coil over straight tube is evaluated in terms of enhancement parameter. The enhancement parameter is higher than one for mass fluxes lower than 200 kg m À2 s À1 . The correlations have been developed to predict two-phase Nusselt number and frictional pressure drop multiplier during condensation of R-134a inside horizontal helical coil tube.

Hydrogen and carbon NMR spectroscopy have been used to investigate the chemical modi®cation process of titanium isopropoxide by acetic acid. The spectra con®rm the belief that the titanium isopropoxide exchanges isopropyl groups with modifying acetate groups to form a molecule with approximate stoichiometry Ti(OiPr) 2 (OAc) 2 . This stoichiometry results even when enough acetic acid is present in solution to allow for signi®cantly higher isopropyl replacement. In addition, progressive esteri®cation to form isopropyl acetate results in a gradually increasing level of condensation and oxo-bridging between the Ti oligomers. Throughout the condensation process, the remaining Ti-bound acetate and isopropyl groups maintain an approximate 1 : 1 ratio, suggesting that oxo-bridge formation occurs through a transesteri®cation process. #

Our work is aimed at the development of numerical method for the modeling of transonic flow of wet steam including condensation/evaporation phase change. We solve a system of PDE's consisting of Euler or Navier-Stokes equations for the mixture of vapor and liquid droplets and transport equations for the integral parameters describing the droplet size spectra. Numerical method is based on a fractional step technique due to the stiff character of source terms, i.e. we solve separately the set of homogenous PDE's by the finite volume method and the remaining set of ODE's either by explicit Runge-Kutta or implicit Euler method. The finite volume method is based on the Lax-Wendroff scheme with conservative artificial dissipation terms for structured grid. We also note result achieved by recently developed finite volume method with VFFC scheme. We discuss numerical results of steady and unsteady two-phase transonic flow in 2D nozzle, 2D and 3D turbine cascade and 2D turbine stage with moving rotor cascade.

This study experimentally investigated the performance of a solar driven (by parabolic trough collector) steam jet ejector chiller (SJEC) having a cooling capacity of 1 kW. The experiments show the particular characteristics of a SJEC with the strong influence of the condenser temperature, T cond , and evaporator temperature, T evap , on the coefficient of performance (COP). A decrease in the condenser temperature by 12°C, in case of an evaporator temperature of T evap = 7°C the COP was increased by 57%, while for T evap = 13°C the COP was increased by 41% and for T evap = 17°C the COP was increased by 34.4%, respectively. While at a constant condensation temperature an increase in the evaporator temperature, T evap , from 7 to 13°C, leads to increased COP values ranging from 14% to 56.7%, and increases T evap from 7 to 17°C, lead to increases in COP values ranging from 53% to 132%, respectively. These results in general indicate that the COP increases with decreasing condenser temperature, which is determined by the source temperature of the cooling medium and it has the limiting factors controlling the operation of the solar steam ejector refrigeration system.

A systematic engineering study on continuous synthesis of bismuth metal nanoparticles by vapor condensation in tube ows is presented. Simulations of aerosol nucleation, condensation and coagulation are cast in a design diagram format to guide experimental studies on the e ect of process parameters on product nanoparticle characteristics. Flow visualization, tracer gas analysis and computational uid dynamics are used to unravel the e ect of particle residence time distribution on product morphology during evaluation of alternate quenching designs for the metal vapor. Bismuth nanoparticles of average diameter 12-37 nm, as determined by nitrogen adsorption and X-ray di raction, were made by controlling the quenching gas ow rate, carrier gas ow rate and process pressure. ?

This preliminary proposal and the original research within it was recommended in June 2016 by The Prince of Wales and The Duchess of Cornwall to His Royal Highness's International Sustainability Unit.

It is a massive project, 800 sq miles of inhospitable desert. It is the hope of my tribe and myself that even if this project never receives funding, the research within it will help millions of people around the world, it is our humble gift to the world.

Here we argue that life emerged on Earth from a redox and pH front at c. 4.2 Ga. This front occurred where hot (c. 150 C), extremely reduced, alkaline, bisulphide-bearing, submarine seepage waters interfaced with the acid, warm (c. 90 C), iron-bearing Hadean ocean. The low pH of the ocean was imparted by the ten bars of CO 2 considered to dominate the Hadean atmosphere/hydrosphere. Disequilibrium between the two solutions was maintained by the spontaneous precipitation of a colloidal FeS membrane. Iron monosulphide bubbles comprising this membrane were inflated by the hydrothermal solution upon sulphide mounds at the seepage sites. Our hypothesis is that the FeS membrane, laced with nickel, acted as a semipermeable catalytic boundary between the two fluids, encouraging synthesis of organic anions by hydrogenation and carboxylation of hydrothermal organic primers. The ocean provided carbonate, phosphate, iron, nickel and protons; the hydrothermal solution was the source of ammonia, acetate, HS , H 2 and tungsten, as well as minor concentrations of organic sulphides and perhaps cyanide and acetaldehyde. The mean redox potential (Eh) across the membrane, with the energy to drive synthesis, would have approximated to 300 millivolts. The generation of organic anions would have led to an increase in osmotic pressure within the FeS bubbles. Thus osmotic pressure could take over from hydraulic pressure as the driving force for distension, budding and reproduction of the bubbles. Condensation of the organic molecules to polymers, particularly organic sulphides, was driven by pyrophosphate hydrolysis. Regeneration of pyrophosphate from the monophosphate in the membrane was facilitated by protons contributed from the Hadean ocean. This was the first use by a metabolizing system of protonmotive force (driven by natural pH) which also would have amounted to c. 300 millivolts. Protonmotive force is the universal energy transduction mechanism of life. Taken together with the redox potential across the membrane, the total electrochemical and chemical energy available for protometabolism amounted to a continuous supply at more than half a volt. The role of the iron sulphide membrane in keeping the two solutions separated was appropriated by the newly synthesized organic sulphide polymers. This organic takeover of the membrane material led to the miniaturization of the metabolizing system. Information systems to govern replication could have developed penecontemporaneously in this same milieu. But iron, sulphur and phosphate, inorganic components of earliest life, continued to be involved in metabolism.

Gesture recognition pertains to recognizing meaningful expressions of motion by a human, involving the hands, arms, face, head, and/or body. It is of utmost importance in designing an intelligent and efficient human-computer interface. The applications of gesture recognition are manifold, ranging from sign language through medical rehabilitation to virtual reality. In this paper, we provide a survey on gesture recognition with particular emphasis on hand gestures and facial expressions. Applications involving hidden Markov models, particle filtering and condensation, finite-state machines, optical flow, skin color, and connectionist models are discussed in detail. Existing challenges and future research possibilities are also highlighted.

In the present thesis we have found constraints on the fundamental Planck scale within extra dimensional models, by analyzing the torsion induced four-fermion interaction and the LHC data. Additionally, such an interaction induces corrections to the one-loop observables within the Standard Model (SM) of particle physics, which was used to obtain more stringent constraints on the fundamental Planck scale through the SM precision measurements. Further, it was argued that the Yukawa sector of the SM may arise from the condensation of a fourth family of heavy quarks, through the four-fermion interaction in gravity with torsion. This approach gives rise to a composite Higgs boson. Finally, we considered two different scenarios of torsion-descended axions and demonstrated that they are equivalent from the effective theory point of view. We studied the solution to the strong CP problem using such kind of torsion-descended axions and examined some of their cosmological implications.

In the present study a gas/liquid two-phase flow and the simultaneous evaporation and condensation phenomena in a thermosyphon was modeled. The volume of fluid (VOF) technique was used to model the interaction between these phases. Experiments in a thermosyphon were carried out at different operating conditions. The CFD predicted temperature profile in the thermosyphon was compared with experimental measurements and a good agreement was observed. It was concluded that CFD is a useful tool to model and explain the complex flow and heat transfer in a thermosyphon.

The sol-gel method for the mullite synthesis is reviewed, with particular emphasis on the characterization of monophasic and diphasic gels at low, intermediate and high temperatures and the factors that influence the hydrolysis and condensation rate of the sol-gel process, which in turn determine the properties of the final material. A wide range of studies about mullite precursors synthesized via sol-gel is discussed here. J Sol-Gel Sci Technol (2010) 55:111-125 113 O-Si-O bend (SiO 4 ) and Al-O-Al bend (AlO 6 )

The emergence of dramatic morphological differences (disparity) and the ensuing bewildering increase in the number of species (diversity) documented in the fossil record at key stages of animal and plant evolution have defied, and still defy, the explanatory powers of Darwin's theory of evolution by natural selection. Among the best examples that have captured the imagination of the layman and the interest of scores of scientists for  years are the origins of land plants from aquatic green plants, of flowering plants from seed plants, of chordates from non-chordates and of tetrapod vertebrates from non-tetrapods; and the conquest of the land by amphibians; the emergence of endotherms from ectotherm animals; the recurrent invention of flight (e.g. in arthropods, birds and mammals) from non-flying ancestors; and the origin of aquatic mammals from fourlegged terrestrial ancestors.

As a result of the increased amount of time that people tend to stay indoors nowadays, it has grown the concern about thermal comfort and air quality. Although there is a huge technological evolution on the thermal energy conservation systems and indoor air quality, on construction nowadays, the preexisting buildings are not following the
evolution, ending up presenting a thermo-hygrometric behavior that can sometimes jeopardize the comfort, health or activities of its users.
With that in mind, and due to the great amount of children and young people, it can be understood why the thermo-hygrometric behavior plays an important role in schools.
The purpose of this study it is to characterize the indoor environment quality in eight schools, through a detailed analysis of the hydrothermic main parameters of eight classrooms, such as: the temperture (environment and surface), the relative humidity (environment and engaging surface), and the air flow level. This dissertation presents the results of measurements made in eight classrooms, that have allowed the thermo-hygrometric characteristics comparison between all eight respective schools. It is also presented, in order to supplement the theme, the estimated level of termal confort, due to the acquired environmental conditions, and interior condensation risk analysis.

The performance of an annular fin with uniform thickness losing heat by convection to its surroundings is studied analytically for two sets of boundary conditions: (a) simultaneously prescribed base temperature and base heat flux, (b) specified base and tip temperatures. For (a) analytical expressions are derived for the temperature distribution, the tip heat flow, and the Biot number at the tip. For the fin tip to be insulated, a relationship between the base heat flow, the radii of the fin, and the fin parameter must be satisfied. Based on the base heat flow for the insulated tip, an expression is derived for the tip temperature. For part (b), analytical solutions are presented for the temperature distribution, base heat flow, and tip heat flow. For the adiabatic tip condition, a relation between the tip temperature, the fin parameter, and the radii of the fin must be satisfied. The condition under which the fin tip can be freely exposed to the environment is established. The graphical results provide a comprehensive picture of the thermal performance of the annular fin under both cooling and heating conditions.

The key objective of this study is to analyse the heat transfer processes involved in the evaporation and condensation of water in a water distillation system employing a thermoelectric module. This analysis can help to increase the water production and to enhance the system performance. For the analysis, a water distillation unit prototype integrated with a thermoelectric module was designed and fabricated. A theoretical model is developed to study the effect of the heat added, transferred and removed, in forced convection and laminar flow, during the evaporation and condensation processes. The thermoelectric module is used to convert electricity into heat under Peltier effect and control precisely the absorbed and released heat at the cold and hot sides of the module, respectively. Temperatures of water, vapour, condenser, cold and hot sides of the thermoelectric module and water production have been measured experimentally under steady state operation. The theoretical and experimental water production were found to be in agreement. The amount of heat that needs to be evaporated from water-vapour interface and transferred through the condenser surface to the thermoelectric module is crucial for the design and optimization of distillation systems.

This paper presents experimentally determined heat transfer coefficients for condensation from a superheated vapor of CO 2 and R410A. The superheated vapor was flowed through a smooth horizontal tube with 6.1 mm ID under almost uniform temperature cooling at reduced pressures from 0.55 to 0.95, heat fluxes from 3 to 20 kW m À2 , and superheats from 0 to 40 K. When the tube wall temperature reaches the saturation point, the measured results show that the heat transfer coefficient gradually starts deviating from the values predicted by a correlation valid for single-phase gas cooling. This point identifies the start of condensation from the superheated vapor. The condensation starts earlier at higher heat fluxes because the tube wall temperature reaches the saturation point earlier. The heat transfer coefficient reaches a value predicted by correlations for condensation at a thermodynamic vapor quality of 1. The measured heat transfer coefficient of CO 2 is roughly 20-70% higher than that of R410A at the same reduced pressures. This is mainly because the larger latent heat and liquid thermal conductivity of CO 2 , compared to that of R410A, increase the heat transfer coefficient.

Hydrocarbons are one of the candidates for refrigerants of next generation heat pump and refrigeration systems. Although the hydrocarbons have superior thermophysical properties as a refrigerant to fluorocarbons and are widely used in domestic refrigerators, their flammability prevents their wide application to larger systems, such as residential and packaged air conditioners, car air conditioners, heat pumps, etc. In this paper, recent studies on condensation of hydrocarbons are reviewed since it is one of the key technologies. For in-tube condensation, heat transfer coefficients of smooth tubes are correlated well with previously proposed equation developed with data of the fluorocarbons. On the other hand, few data are available for enhanced tubes. In the case of condensation on a horizontal tube, heat transfer of smooth tube is explained well by the Nusselt theory. However, different heat transfer characteristics appear for enhanced tubes. Since blended hydrocarbons would be used to obtain suitable properties, models of mixed vapor condensation are also reviewed.

Water scarcity and pollution pose critical situation in all walks of life especially in the developing countries. Among the available purification technologies, solar desalination process proves to be a suitable solution for resolving this existing crisis. This renewable energy technology operates on a basic principle of which the solar radiation enters through the glass surface inside a closed chamber touching the black surface generating heat energy, which gets trapped inside. This gradually raises the temperature of the liquid resulting in evaporation process and further condensation, which is drained out for use. In this connection, a basin type solar still (0.5 m 2 ) with improved condensation technique was designed and built, and a performance study was carried out with different samples such as tap water, seawater and dairy industry effluent. The condensation occurs due to the temperature difference not only on the glass surface but also on the four sidewalls, which can be cooled by water circulation through tubes attached on the wall surface for efficiency enhancement. The maximum daily production of the solar still was about 1.4 L/m 2 .d, and its efficiency was about 30%. The condensate water quality was analysed and compared with water quality standards, which was found to be comparable with rainwater and mineral water. Efficiency of the still was calculated for all the samples and compared with each other. The reasons for the findings and their implications for the design of the system are discussed. Some design features that would further enhance the thermal performance of the still were also identified from this present investigation and highlighted.

Professor, Higher College of Technology, Oman. Introduction -Plate heat exchangers (PHEs) were introduced in the 1930s and were almost exclusively used as liquid/liquid heat exchangers in the food industries because of their ease of cleaning. Over the years, the development of the PHE has generally continued towards larger capacity, as well as higher working temperature and pressure. Recently, a gasket sealing was replaced by a brazed material, and each thermal plate was formed with a series of corrugations (herringbone or chevron). These greatly increased the pressure and the temperature capabilities.

This article studies the anti-ice performance of several micro/nano-rough hydrophobic coatings with different surface chemistry and topography. The coatings were prepared by spin-coating or dip coating and used organosilane, fluoropolymer or silicone rubber as a top layer. Artificially created glaze ice, similar to the naturally accreted one, was deposited on the nanostructured surfaces by spraying supercooled water microdroplets (average size ˜80 μm) in a wind tunnel at subzero temperature (-10 °C). The ice adhesion strength was evaluated by spinning the samples in a centrifuge at constantly increasing speed until ice delamination occurred. The results show that the anti-icing properties of the tested materials deteriorate, as their surface asperities seem to be gradually broken during icing/de-icing cycles. Therefore, the durability of anti-icing properties appears to be an important point for further research. It is also shown that the anti-icing efficiency of the tested superhydrophobic surfaces is significantly lower in a humid atmosphere, as water condensation both on top and between surface asperities takes place, leading to high values of ice adhesion strength. This implies that superhydrophobic surfaces may not always be ice-phobic in the presence of humidity, which can limit their wide use as anti-icing materials.

The reaction of 4-oxo-4H-chromen-3-carbaldehydes with coumarin-4-acetic acids under the Perkin conditions follows an interesting pathway that involves aldol reaction and subsequent intramolecular lactonization to afford 2-oxo-2H,5H-pyrano[3,2-c]chromene skeleton. In contrast to chromone-3-carbaldehydes, the same reaction with chromone-2-carbaldehydes yielded only the aldol condensation product. The reaction was performed under thermal and microwave conditions. The reactivity of 2-oxo-2H,5H-pyrano[3,2-c]chromenes in water, alcohol and acetic acid was described.

The essential need to life is water. Although the ocean is enormous in nature, but its saltwater is high in salinity level which makes it undrinkable. The salinity level of saltwater might go around 35 000 parts per million (ppm) or even more. For water to be drinkable, it has to have a salinity level of 1000 parts per million (ppm) or less. This creates a problem in some coastal areas where clean water facilities are not easily accessible to its inhabitants. Besides, rapid growth in human population and industrial has increases the consumption of water, which as far as it can go, this problem affects certain countries like India and Africa to lacking in fresh, clean water supply.

The use of CFD codes for the analysis of the hydrogen behaviour within NPP containments during severe accidents has been increasing during last years. In this paper, the adaptation of a commercial multi-purpose code to this kind of problem is explained, i.e. by the implementation of models for several transport and physical phenomena like: steam condensation onto walls in presence of non-condensable gases, heat conduction, fog and rain formation, material properties and criteria for assessing the hydrogen combustion regime expected. The code has been validated against several experiments in order to verify its capacity to simulate the following phenomena: plumes, mixing, stratification and condensation. Moreover, two tests in an integral large enough experimental facility have been simulated, showing that the well-mixed and stratified conditions of the test were reproduced by the code. Finally, an example of a plant application demonstrates the ability of the code in this kind of problems.

An experimental investigation of condensation heat transfer in 9.52 mm O.D. horizontal copper tubes was conducted using R22 and R410A. The test rig had a straight, horizontal test section with an active length of 0.92 m and was cooled by the heat transfer fluid (cold water) circulated in a surrounding annulus. Constant heat flux of 11.0 kW/m 2 was maintained throughout the experiment and refrigerant quality varied from 0.9 to 0.1. The condensation test results at 45 8C were reported for 40-80 kg/h mass flow rate. The local and average condensation coefficients for seven microfin tubes were presented compared to those for a smooth tube. The average condensation coefficients of R22 and R410A for the microfin tubes were 1.7-3.19 and 1.7-2.94 times larger than those in smooth tube, respectively. q

Biomineral formation is widespread in Nature and occurs in bacteria, single-celled protists, plants, invertebrates and vertebrates. Minerals formed in the biological environment often show unusual physical properties (e.g., strength, degree of hydration) and often have structures that exhibit order on many length scales. Biosilica, found in single cell organisms through to higher plants and primitive animals (sponges) is formed from an environment that is undersaturated with respect to silicon and under conditions of around neutral pH and low temperature ca. 4-40 °C. Formation of the mineral may occur intra-or extra-cellularly and specific biochemical locations for mineral deposition that include lipids, proteins and carbohydrates are known. In most cases the formation of the mineral phase is linked to cellular processes, understanding of which could lead to the design of new materials for biomedical, optical and other applications.

Thermal conversion process was applied with three types of waste plastic mixture and waste plastics mixture to liquid hydrocarbon fuel production in present of o xygen under laboratory Labconco fu me hood without adding any kind of catalyst. Utilization of the process described can reduce the impact of waste plastics significantly. Thermal decomposition of the most co mmon plastics such as high density polyethylene (HDPE), polypropylene (PP) and polystyrenes (PS) has been conducted to produces a mixture of hydrocarbons. The thermal process applied of mixed waste plastics using a steel reactor at 25-430℃ has been investigated. The reactor was connected with standard condensation unit with water circulator system. Waste plastics are broken down into shorter chain hydrocarbon compounds from long chains during the thermal conversion process without adding catalyst or chemical. Produced fuel was analysis by using GC/M S, FT-IR and DSC and fro m GC/MS analysis result showed hydrocarbon chain range C 3 to C 28 into fuel and produce fuel can be use as feed stock refinery or power plant for electricity generation or can use for internal co mbustion engine.