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This work involves an experimental investigation of a novel air gap membrane distillation (AGMD) unit with an installed circulating fan within the condensation chamber. The installed fan breaks the resistance to mass and heat transfer in the gap chamber by inducing fluid mixing and a turbulent dissipation rate, which enhances the overall mass and heat transfer characteristics of the system and consequently the overall performance of the system. The system performance, such as vapor flux, specific thermal energy consumption (STEC), and desalinated water cost, of the new AGMD is evaluated and compared to the traditional AGMD system. The influence of fan design variables, including fan revolution, fan thickness, and fan diameter, on system performance is investigated. Furthermore, the effect of feed water temperature on the system's performance is assessed and presented. Results indicate that fan speed significantly improves the performance of the new AGMD system compared to conventional AGMD designs. Fan thickness recorded a marginal effect, and fan diameter registered some influence, while fan revolution exhibits the strongest impact on the system's performance. The new system can attain a maximum flux and minimum STEC of 34.16 kg/m2·h and 710.72 kWh/m3, respectively, as against the conventional units, which registered a peak vapor flux and lowest STEC of 17.69 kg/m2·h and 1,141.25 kWh/m3, respectively. [ABSTRACT FROM AUTHOR]

Summary: Due to the depletion of fossil fuel sources and their pollution, renewable energy sources have attracted researchers' attention for energy supply; power generation using solar energy is one of the most important examples of these sources. This energy needs to be saved because of climate changes, to be used with high confidence. In this investigation, the heating and cooling of 100 Conex in Riyadh, Saudi Arabia, was studied, which used hydrogen storage as the central storage system. The main purpose of this project is to determine the ratio of fuel cell power to the electrolyzer power in this storage system, to reach the minimum dependency of the system on the urban power grid and at the same time, the minimum cost of electrolyzer and fuel cell. Because the shelters were simulated by Energy Plus and Open Studio Software and the energy supply system by TRNSYS Software, the optimization was not possible. Therefore, this system was changed into a network in MATLAB Software after simulation with deep learning artificial intelligence; then, it was optimized by a genetic algorithm. In order to accurately form a network, different parameters of artificial intelligence were studied precisely. The best result was obtained from a neural network with two hidden layers, each one containing 10 neurons, sigmoid activation function, and without dropout, with a correlation coefficient of 0.9998, which shows an excellent accuracy. The results of optimization also indicated that at all points, the Pareto front for fuel cell power is less than or equal to the power of the electrolyzer, and this ratio is 0.47 at the optimum point in terms of cost and electric consumption. [ABSTRACT FROM AUTHOR]

Carbonated water drops impact on a hydrophobic surface is examined. The influence of CO2 gas bubbles in droplet fluid on impacting droplet characteristics, such as spreading rates and restitution coefficient, are explored. The predictions of droplet wetting diameter and spreading rates are validated through the experimental data obtained from high-speed recording. The findings reveal that predictions agree well with the experimental data. CO2 gas bubbles in the droplet are compressed by the total impact pressure of the droplet liquid while slightly reducing the gas bubble sizes. The small size of close by bubbles at high pressure can merge forming large size bubbles, which occur toward the end of droplet spreading and retraction periods. The pressure increase in the fluid gives rise to the increased vertical height of the droplet and slightly reduces the droplet contact diameter on the impacted surface. The work done during the compression of CO2 gas in bubbles lowers the restitution coefficient of the droplet after the retraction period. [ABSTRACT FROM AUTHOR]

Impacting water droplet on a hydrophobic soft surface is investigated and impacting droplet behavior during the spreading and retraction phases is examined. Polyisoprene elastomer surface is hydrophobized via deposition with functionalized nanosilica particles using the dip coating method. Hydrophobized surface results in the contact angle of 135±3deg with a hysteresis of 2±1deg, and stretching and stretch relaxing of the coated samples do not alter the wetting state of the surfaces. Pressure variation, spreading, and retraction rates of droplet are simulated and findings are validated through the experimental data obtained from high-speed video system. The findings are also compared to those obtained for the impacting droplet on the hydrophobized glass surfaces. It is observed that predictions of droplet height and droplet shape agree well with the experimental data. Spreading period of the impacting droplet on the hydrophobized elastomer surface is longer than the hydrophobic glass surface; contrary, the retraction period of the impacting droplet is shorter on the elastomer surface than the glass surface. Impacting droplet generates large amplitude oscillatory surface waves on the elastomer surface and as the time progresses the wave amplitude reduces considerably, particularly along the surface (x-axis). [ABSTRACT FROM AUTHOR]

Gas nitriding is a common surface treatment practice to improve the wear resistance of AISI 1113 hot extrusion die cavities. However, due to the presence of complex and sharp features of die cavities, it has been observed that nonuniform nitride layer develops in these regions. Moreover, the formation of compound layer in the surface vicinity of nitrided surfaces leads to the development of transformation-induced stresses. The present work presents the application of the phase field method in predicting the evolution of the nitride layers and associated residual stresses during the gas nitriding of AISI HI 3 tool steels. Nitriding process is modeled and simulated in line with experimental setup, which uses automated two-stage controlled nitriding process. Some representative samples having commonly used geometric features are manufactured and nitrided for validation purpose. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding microhardness profiles. The results show that high stresses are induced at the surface due to formation of the nitride layers, and these stresses are found to be higher at the sharp corners. In view of the current results, some process and design strategies are suggested for improved and more effective nitriding treatment of hot extrusion dies used in the industry. [ABSTRACT FROM AUTHOR]