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Go to Editorial ManagerImprovements in the thermo-physical properties of Phase Change Materials (PCM) caused by nanoparticle dissipation are critical for a wide range of technologies. The current study describes numerically the investigation of the charging and discharging process of paraffin wax dispersed with different concentrations (1%, 3%, 5%, 7%, and 10% ) of Alumina nanoparticles (Al2O3), in a Single Thermal Energy Storage (STES) system. For this study, a time-dependent, two-dimensional simulation of the solidification and melting process was performed numerically for different velocities. The study is realized using the CFD ANSYS FLUENT software package (Version 18) that employs the phase-change phenomenon using the enthalpy technique. The results show that adding alumina nanoparticles to paraffin wax reduces the melting and solidification process, and raising nanoparticle concentration accelerated the melting and solidification process even more when compared to pure paraffin wax. The greatest improvement was obtained with the maximum concentration of nanoparticles with total time saving between (12% - 11.76% ) in the charging process and between ( 15.71% - 19.60% ) in the discharging process depending on velocity. Furthermore, other important findings were that the presence of nanoparticles makes a little effect in the early stages of the solidification and melting processes, but as time passes, the rate of solidification and melting rises. Comparison with previous works gave good agreement of about 34%.
Pressure vessels are the heart of plants and oil refineries stations. In many engineering applications such vessels can be subjected to periodic loading either internally due to the charging and discharging process or externally due to the excitation from other nearby components such as pumps, compressors or from seismic. So that in spite of a good design according static assumption it may be critical in dynamics. In this work a horizontal pressure vessel with accessories subjected to liquefied petroleum gas pressure LPG is considered. Three models of different head types are investigated herein namely; Deep torispherical, Elliptical 2:1 and Hemispherical. The design and material selections are chosen as per ASME. For practical service many accessories are attached to the vessel such as manhole, supports, inlet and outlet opining. Finite Element method via ANSYS R18.2 is introduced for the numerical analysis. The fatigue life in case of fully reversed cyclic loading are estimated and located. Vibration characteristics such as mode shapes and natural frequencies for the lowest five modes are evaluated and compared. It is found that the fatigue life can be increased as higher as 180% for hemi- spherical head as compared with deep torispherical head pressure vessel and the lowest four natural frequencies are nearly identical for all models, however significant change observed in the fifth natural frequency.
The investigation of the existence of a tempera-ture change with pressure inside the pneumatic cylinder chambers during the charging and dis-charging strokes in the pneumatic cylinder is ex-perimentally demonstrated. Three different varia-bles (pressure, piston displacement and tempera-ture) were measured in this work while operating with a servo pneumatic system and a discussion of the relationship between these variables was pre-sented. The cylinder used has a piston diameter of (0.05m), piston rod diameter (0.02m) and a stroke length of (0.2m). The results show a temperature rise of 23 K above atmospheric temperature at chamber (1) while air compressing and a tempera-ture drop of 17 K below atmospheric temperature at chamber (2) while air expansion and measures other temperature changes also.
Due to the instability and irregular of national electric power supplied to residence sector in Iraq for long term history, attracted researchers interest to strive for solutions, and associated challenge dry and very hot summer season in Iraq on air conditioning application, A test room full size prototype was constructed in Baghdad, its size 33.5m3, the room is built from very good thermal insulation Autoclave Aerated Concrete AAC with white panted Concrete roof, test room is exposed to solar radiation during entire day, thermal energy shifted by time using thermal energy storage TES containing PCM, PCM is soft paraffin its phase inversion temperature (29 to 27)°C, thermal energy was shifted from night timing by cooling down TES (Discharging PCM) to peak time 11:00 am to 02:00 pm, the testes were carried out over entire summer season April to October, the results showed thermal energy can shift to by any quantity and time based on mass of PCM and enthalpy, electrical energy saved at peak time 52.5% of total power spent over season 2.7KW/day, Only 27% of electric energy utilized to discharge PCM during night, about 43% of heat lose is sourced from exposed roof, melting and solidification of PCM temperature must be within indoor comfort range 23 to 28 ?C to release or absorb the latent heat 41kJ/kg.