Water vapour Research Papers - Academia.edu (original) (raw)

Solid materials with a porous structure as a chitosan microparticles are very often applied where their sorption ability plays the main role. In this study, microparticles were formed by means of spray drying of two chitosan salts:... more

Solid materials with a porous structure as a chitosan microparticles are very often applied where their sorption ability plays the main role. In this study, microparticles were formed by means of spray drying of two chitosan salts: acetate and ascorbate, and two cross-linking agents glutaraldehyde and sodium triphosphate were added to the solution. Dry microparticles as a product of different chemical composition had different structural characteristics: shape, size, density, and volume and area of pores. Sorption ability of these microparticles was investigated by measuring the sorption of benzene and carbon dioxide (in a highly-vacuum sorptive instrument) and water vapour. The presented results show that pore volume attains big values when glutaraldehyde is added as a cross-linking substance. But the highest sorption ability of benzene vapour is in the case of microparticles of chitosan acetate without any cross-linking substances. Results of these investigations reveal high possi...

The paper focuses on the redistribution of aerosol particles (APs) during the artificial nucleation and subsequent growth of ice crystals in a supercooled cloud. A significant number of the supercooled cloud droplets during icing periods... more

The paper focuses on the redistribution of aerosol particles (APs) during the artificial nucleation and subsequent growth of ice crystals in a supercooled cloud. A significant number of the supercooled cloud droplets during icing periods (seeding agents: C3H8, CO2) did not freeze as was presumed prior to the experiment but instead evaporated. The net mass flux of water vapour from

The water-binding properties of wheat starch films were studied through the determination of water vapour adsorption isotherms at 20°C. Starch films were obtained by casting after mixing native starch at 95°C for 15min with different... more

The water-binding properties of wheat starch films were studied through the determination of water vapour adsorption isotherms at 20°C. Starch films were obtained by casting after mixing native starch at 95°C for 15min with different ratios of plasticizer (glycerol).Unplasticized starch film was found to adsorb less water than native starch granules. The effect of glycerol on water vapour adsorption by

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external fins when it is used on a car... more

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external fins when it is used on a car equipped with a low pressure EGR. The main unknowns to be answered are the thermo-hydraulic characteristics of the IC working under humid conditions induced by EGR, the conditions under which the water content in the mixture of air and exhaust gases begins to condense and the conditions under which the condensed water will be retained inside the IC. The exhaust gases are here replaced by a mixture of dry air and water vapour which are mixed upstream of the IC. The IC is submitted at the following testing conditions: on the ambient air side, the air temperature is fixed at around 20°C and the air velocity is settled at 1, 2 and 4ms−1; on the exhaust gases side, the supply temperature was varied between 90 and 150°C, with dry gas flow rates of 20, 50 and 100gs−1, and water contents varying between almost 0 and 0.09kgwkgg−1. At these conditions the IC transfers between 1 and 13kW with overall heat transfer conductance varying between 0.05 and 0.38kWK−1 and effectivenesses between 0.3 and 0.97. A water accumulation inside the IC was detected for the tests carried out at low dry gas flow rate of 20gs−1 and for all the water content explored here (higher than 0.02kgwkgg−1).

A 3D numerical study was carried out to analyze flow, heat and mass transfer first in a single half-cell cathode channel of proton exchange membrane (PEM) fuel cell. From practical point of view, it is necessary to put the appropriate... more

A 3D numerical study was carried out to analyze flow, heat and mass transfer first in a single half-cell cathode channel of proton exchange membrane (PEM) fuel cell. From practical point of view, it is necessary to put the appropriate number of cells in a stack. Hence, the above study on a single half-cell is extended to a stack of channels. Due to stacking, the assumption of uniform flow distribution would no longer hold true. Therefore, the channel flow-maldistribution is considered. The water formed at the active surface due to the electrochemical reaction diffuses through the porous layer and eventually enters the gas flow duct. The higher gas velocities in the duct result in faster water vapour removal which leads to a lower value of water vapour into the duct and hence a lower Nusselt number.

Hygroscopic behaviour is an inherent characteristic of natural fibres which can influence their applications as textile fabrics and composite reinforcements. In this study, the water vapour sorption kinetic properties of cotton, filter... more

Hygroscopic behaviour is an inherent characteristic of natural fibres which can influence their applications as textile fabrics and composite reinforcements. In this study, the water vapour sorption kinetic properties of cotton, filter paper, flax, hemp, jute, and sisal fibres were determined using a dynamic vapour sorption apparatus and the results were analyzed by use of a parallel exponential kinetics (PEK) model. With all of the fibres tested, the magnitude of the sorption hysteresis observed varied, but it was always greatest at the higher end of the hygroscopic range. Flax and sisal fibres displayed the lowest and highest total hysteresis, respectively. The PEK model, which is comprised of fast and slow sorption components, exhibited hysteresis in terms of mass for both processes between the adsorption and desorption isotherm. The hysteresis derived from the slow sorption process was less than from the fast process for all tested fibres. The fast processes for cotton and filter paper dominated the isotherm process; however, the hemp and sisal fibres displayed a dominant slow process in the isotherm run. The characteristic time for the fast sorption process did not vary between adsorption and desorption, except at the top end of the hygroscopic range. The characteristic time for the slow process was invariably larger for the desorption process. The physical interpretation of the PEK model is discussed.

Adsorption of water vapour on wool provides not only textile comfort, but also convenience in transportation due to increase in its bulk density. The adsorption and desorption isotherms of water vapour for wool were determined by both... more

Adsorption of water vapour on wool provides not only textile comfort, but also convenience in transportation due to increase in its bulk density. The adsorption and desorption isotherms of water vapour for wool were determined by both volumetric technique using a Coulter Omnisorp 100CX instrument and gravimetric method employing a Cahn 2000 electronic microbalance. Adsorption isotherm fitting to B.E.T. model and hysteresis on desorption was observed. The average effective diffusion coefficient of water in wool was found to be 8.4 × 10-14 m2s-1 at 25°C from gravimetric data. The effects of packing height and air velocity on the breakthrough curves were also investigated in the wool packed columns. For pseudo first order model, k values changing between 0.33 × 10-6 − 69 × 10-6 s-1 was obtained for 2.2–6.4 cm s-1 air velocity and 0.05–0.20 m packing height ranges.

The conventional agriculture leads to some important pollution of ground water (particularly, by nitrates). The solution is the coating of fertilizers by degradable polymers. In this work, we have studied the water vapour and liquid... more

The conventional agriculture leads to some important pollution of ground water (particularly, by nitrates). The solution is the coating of fertilizers by degradable polymers. In this work, we have studied the water vapour and liquid diffusion through polymer films detached from their support. Therefore, we may classify polymers as a function of their properties like water vapour and liquid barrier. We may choose the best polymer(s) for coating.coated fertilizers by chosen polymer(s) with mechanical techniques such as fluidised bed and pan coating. Moreover, the electron microscopy used to see the quality of the wall has showed the presence of pores due to the rapid evaporation of solvent. A drying in air current and an annealing could be done to avoid this problem.followed the ions release of fertilizers immersed in distilled water by conductimetry. The more interesting result was obtained with fertilizers coated by polylactic acid. In effect, the total release reached three weeks.

... inserting (Moore & Hoseney, 1986). Oven rise is assessed by loaf height tracker, assuming it is uniaxial, a reasonable assumption for tin-moulded breads (Kilborn, Preston, & Kubota, 1990). This measurement is important... more

... inserting (Moore & Hoseney, 1986). Oven rise is assessed by loaf height tracker, assuming it is uniaxial, a reasonable assumption for tin-moulded breads (Kilborn, Preston, & Kubota, 1990). This measurement is important since ...

Buildings with indoor swimming pools are recognised as very high-energy consumers and present a grate potential for saving energy. The management of indoor ambient conditions must act upon the most sensible parameters that affect the... more

Buildings with indoor swimming pools are recognised as very high-energy consumers and present a grate potential for saving energy. The management of indoor ambient conditions must act upon the most sensible parameters that affect the energy consumption; the energy is spending in several ways: Evaporation heat loss from the pool; ambient temperatures very high; and High rates of ventilation required. Control Strategies adapted to the reality of each building is an important way to reduce energy consumption. These paper presents control strategies that can implemented in the building automation system and the HVAC system of an existing indoor swimming pool complex, in order to minimise energy consumption. Taking into account the complexity of the parameters involved in a feasibility study of measures to reduce the energy consumption of the building, the choice of energy simulation programs is actually the better way, either from both economical and time perspectives, to quantify the b...