Evaporation studies of water using classical molecular dynamics simulations are largely limited due to its high computational expense. We aim at addressing the computational issues by developing a coarse grain model for evaporation of water on solid surfaces by combining four water molecules into a single bead. Most commonly used mono atomic pair potentials like Lennard Jones, Morse, Mie and three body potential like Stillinger-Weber are optimized using a combination of Genetic algorithm and Nelder-Mead algorithm. Among them, Stillinger-Weber based model shows excellent agreement of density and Enthalpy of vaporization with experimental results for a wide range of temperatures. Further, the new water model is used to simulate contact angle of water and thin film evaporation from surfaces with different wettabilities.
The Photovoltaic modules are usually installed on the ground which exposes it to surface deposition of foreign particles. In the Middle East and North Africa region, the primary culprit is dust and sand. They form an insulating and opaque layer on the surface of the glass, which obstructs its heat transfer and optical properties, thereby reducing the overall yield efficiency of the solar panel. Cleaning of this layer is critical to the operation of the solar panel and often requires great effort and energy on a large-scale solar array. In this paper, we propose a novel self-cleaning mechanism for solar panels, with an understanding of the structural integrity of the Photovoltaic laminate and application of external mechanical vibration. By applying an external source of vibration, the solar panels vibrate, excites its fundamental frequencies and cleans by its own. The method is analyzed using finite element analysis method and tested using experiments. Our simulation results based on IEC 61215 show that the maximum principal stress and deformation in the critical layers is within limits. Our experimental results prove the proposed theory is feasible and can be extended to large scale solar arrays. Our proposed method is retrofittable and could save money, energy and effort in cleaning the solar arrays, which can replace current techniques.
Flow of paraffinic hydrocarbon liquids within extended pipeline networks or wells, where the environment/bulk temperature is below the cloud point or wax-appearance temperature (WAT), could result in precipitation of wax from the bulk fluid. Precipitated wax crystals from crudes deposits on the inner pipe wall could lead to reduced flow area or even complete blockage and could present a costly problem in the production and transportation of petroleum products. Timely removal of such deposits is extremely important to avoid associated problems. This paper illustrates a numerical approach to estimate the deposition profile and its effect on flow-related parameters. Later, the procedure is validated with field data from a North Sea offshore production facility. This paper also seeks to propose a feasible solution to avoid such flow-assurance issues; in doing so, current commonly practiced reduction and preventive methods are reviewed. Previously, providing thermal insulation with aerogel foam had proved to be the most effective option in preventing wax from precipitating. A relatively new approach is discussed in this paper, which allows for minimizing the usage of insulation material in an attempt to reduce the implementation cost of the proposed precaution. Theoretical implementation of the procedure was also conducted to identify its effectiveness, which was later found to be elimination of the deposition completely.
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