Experimental and theoretical study of an integrated thermoelectric–photovoltaic system for air dehumidification and fresh water production

The main objective of this study is to present an integrated thermoelectric–photovoltaic renewable system to dehumidify air and produce fresh water. The system is combined with a solar distiller humidifying ambient air to enhance distillate output to meet the specified fresh water needs for a residential application. A model is developed to simulate the air dehumidification process using thermoelectrically cooled TEC channels. Experiments were performed to validate the developed model results. It is found that the model predicted well the variation in the air temperature along the channel with a maximum relative error in air temperature less than 2.4%. In addition, the simulation model predicted well the amount of water condensate produced by the integrated system with a maximum relative error of 8.3%. An optimization problem is formulated to design and set the integrated system optimal operation to produce 10 L of fresh water per day meeting the fresh water needs of a typical residential. Using five TEC channels of a length of 1.2 m and an area of 0.07 × .05 m² integrated with 1.2‐m² solar distiller that recirculates a constant air mass flow rate of 0.15 kg s^?1 is capable of meeting water demand when air mass flow rate through each TEC channel is optimally set at 0.0155 kg s^?1. The associated optimal electrical current input to the TEC modules varied depending on the month and is set at 2.2 A in June, 2.1 A in July and 2.0 A in August, September and October. Copyright © 2011 John Wiley & Sons, Ltd.     

A Clothing Ventilation and Heat Loss Electric Circuit Model with Natural Convection for a Clothed Swinging Arm of a Walking Human

This work aims to develop a computationally effective electric circuit model to estimate the ventilation and heat transfer for walking human in the presence of natural convection. The ventilation circuit includes flow resistance, inductance, and electromotive force elements. It is coupled to an electric resistance circuit of heat flows to adjust the temperature difference inducing natural convection flow. The coupled ventilation and heat circuit models predicted both the segmental ventilation rate and heat loss from the arm at different walking and wind speeds. The developed model of the segmental ventilation and heat transfer from the clothed human segment was validated by performing experiments on a walking thermal manikin using tracer gas method. Good agreement was observed between the model predictions and the experiment at a maximum relative error of 10% lying within the standard deviation range. Results showed that the simplified ventilation-heat circuit models succeeded in estimating the natural convection effect at low computational cost. Moreover, it was shown that the effect of natural convection is more significant in walking at no wind than in windy condition. Accounting for natural convection effect increases the segmental ventilation and heat loss at low air permeability (0.02 m/s) by 68% and 20%, respectively.     

Natural ventilation in Beirut residential buildings for extended comfort hours

This paper examines the effectiveness of natural ventilation in Beirut for the purpose of extending comfort periods within living and sleeping zones of the residential buildings. A field survey is conducted to estimate the common window opening and degree profiles. A base case model representing a typical residential apartment located in Beirut was then adopted in integrated environmental solutions (IES) software and calibrated by experimentation through monitoring simulated and measured data indoor. The calibrated IES model was used to evaluate typical wall layering and building local materials and their role in improving indoor comfort with natural ventilation. The simulation results showed that an optimal wall configuration of higher insulation and capacitance, comprised of a 5?cm layer of strawboard sandwiched between a 2?cm?×?10?cm wall of masonry Hempcrete units, achieved the highest degree of thermal comfort and enhanced comfort in winter season when compared to the base case.     

Corrosion par piqûres des alliages d'aluminium 5083-H321 et 6061-T651

Résumé Le comportement des alliages d'aluminium 5083-H321 et 6061-T651 en milieux aqueux avec deux concentrations de l'ion chlore en' présence et en absence de l'ion sulfate a été étudié par voie électrochimique. Les études potentiocinétiques ont permis de déterminer le potentiel de piqûres, tandis que les études potentiostatiques ont précisé davantage l'agressivité du milieu. Trois zones de pH ont été étudiées avec les deux techniques mentionnées, soit: 1–4, 4–9 et 9–12. Une étude morphologique au moyen de la microscopie électronique à balayage combinée par la méthode d'analyse de surface EDAX a été effectuée.

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The behaviour of aluminium alloys 5083-H321 and 6061-T651 in aqueous media containing two different concentrations of chloride ion, in the presence and in the absence of sulphate ion has been studied by electrochemical means. The potentiodynamic studies have permitted determination of the pitting potential, while the potentiostatic studies yielded information on the aggressiveness of the medium. The three regions of pH, studied with the two techniques are: 1–4, 4–9 and 9–12. A morphological study by scanning electron microscopy combined with (EDAX) analysis has been carried out.

     

Fuzzy logic control based maximum power tracking of a wind energy system

In this paper a utility interactive wind energy conversion system (WECS) with an asynchronous (AC–DC–AC) link is described. The control system has the objective of identifying and extracting the maximum power from the wind energy system and transferring this power to utility. A fuzzy logic control (FLC) technique has been implemented to design the tracking controller of the WECS. A wind speed step model was used in the design phase. The performance of the WECS with the proposed fuzzy logic controller is tested using real meteorological data. Its robustness and effectiveness are demonstrated by the simulation results of the controlled system.     

Security of medical images for telemedicine: a systematic review

Multimedia Tools and Applications - Recently, there has been a rapid growth in the utilization of medical images in telemedicine applications. The authors in this paper presented a detailed...     

Fabrication and characterization of flexible ruthenium oxide-loaded polyaniline/poly(vinyl alcohol) nanofibers

Polyaniline/poly(vinyl alcohol)/ruthenium oxide (RuO₂) composite nanofibers were produced by electrospinning technique. Hydrous ruthenium chloride was used as a precursor at different concentrations, and the samples were annealed at 200°C. The morphology of the nanofibers was investigated by scanning electron microscopy. The average diameter of the produced nanofibers is between 200 and 300 nm. Fourier transform infrared spectroscopy and Raman spectroscopy were used for the investigation of the vibration modes and structure of the samples. Differential scanning calorimeter, and thermal gravimetric analysis up to 400°C revealed the crystallinity degree and thermal stability of the samples. Impedance spectroscopy for the samples with capacitor structure was conducted as function of RuO₂ concentration and temperature. The tests revealed the decrease of electrical resistivity and activation energy with increasing RuO₂ concentration for the as-prepared samples, while the annealed samples showed lower activation energy values of ~0.1 eV with increasing the concentration of RuO₂. The electrical properties of the fabricated composite nanofibers could be controlled that make them suitable to be utilized in devices for energy storage applications.     

Electrochemical noise studies of the corrosion behaviour of lead anodes during zinc electrowinning maintenance

Following anodic polarisation of lead anodes with different silver contents (0.5-0.7%) during Zn electrowinning, the discharge and corrosion of lead anode during the decay period at open circuit potential in sulphuric acid bath have been studied by electrochemical noise analysis (ENA) method. Potential and current decay behaviour over 16 h shows 4 and 2 main characteristic regions, respectively. The wavelet transform has been employed to analyse the ENA data. The results of wavelets have demonstrated that energy distribution plot “EDP” was a powerful tool to provide useful information about the dominant process for different discharge and corrosion stages and mechanisms. The discharge is predominant than corrosion for all anodes for the regions I, II and III, and ENA feature of events changes from large timescale to low timescale, diffusion control or exfoliation to metastable pitting and pit growth, respectively. Region IV, only observed for 0.6% and 0.7%Ag, corresponds to general and metastable pitting corrosion under diffusion control. It has been found that anode containing lower silver content have more corrosion products even after 16 h of decay (discharge and attack dominated by pitting corrosion type with the highest corrosion due to the longest period of pitting during the 16 h).