The solidification process in a multi-tube latent heat energy system is affected by the natural convection and the arrangement of heat exchanger tubes, which changes the buoyancy effect as well. In the current work, the effect of the arrangement of the tubes in a multi-tube heat exchanger was examined during the solidification process with the focus on the natural convection effects inside the phase change material (PCM). The behavior of the system was numerically analyzed using liquid fraction and energy released, as well as temperature, velocity and streamline profiles for different studied cases. The arrangement of the tubes, considering seven pipes in the symmetrical condition, are assumed at different positions in the system, including uniform distribution of the tubes as well as non-uniform distribution, i.e., tubes concentrated at the bottom, middle and the top of the PCM shell. The model was first validated compared with previous experimental work from the literature. The results show that the heat rate removal from the PCM after 16 h was 52.89 W (max) and 14.85 W (min) for the cases of uniform tube distribution and tubes concentrated at the bottom, respectively, for the proposed dimensions of the heat exchanger. The heat rate removal of the system with uniform tube distribution increases when the distance between the tubes and top of the shell reduces, and increased equal to 68.75 W due to natural convection effect. The heat release rate also reduces by increasing the temperature the tubes. The heat removal rate increases by 7.5%, and 23.7% when the temperature increases from 10 °C to 15 °C and 20 °C, respectively. This paper reveals that specific consideration to the arrangement of the tubes should be made to enhance the heat recovery process attending natural convection effects in phase change heat storage systems.
Reverse Phase High Performance Liquid Chromatography (RP-HPLC) was coupled with ultraviolet absorption sepectoscopy (UV) for separation and identification of Naphthalene, Acenaphthylene, Pyrene, Benz{a} anthracene and 1,3,2,4-Dibenzanthracene. RP-HPLC was performed on an ODS-C18 column (150×4.6 mm I.D) using acetonitrile–buffer phosphate as mobile phase. UV absorption spectra of the elutes was detected in 254 nm, and studying the chromatographic variables include organic modifier ratio, PH, column temperature and concentration of buffer to maximize resolution and minimize separation time. the results showed that using mobile phase( 80:20) v/v acetonitrile:0.01M phosphate buffer solution at PH 6 with flow rate 1ml/min and column te
... Show MoreThe aim of the research was to prepare the fields and items for safe environment scale form professional basketball players and coaches’ point of view. The researchers used the descriptive method on professional athletes of players and coaches from (11) clubs; for the pilot study (21) athletes were selected and for the building sample (103) athletes, and standardization sample (101) athletes from the participants in the Iraqi league (2018-2019). The scale of the safe environment was concluded with (6) fields and (52) items. The researchers came up with the safe environment scale from the point of view of professional basketball players and coaches. Finally the researchers recommended paying attention to providing safe environment for athl
... Show MoreTHE IMPACT OF BRITISH THEATER UPON IRAQI DRAMA
Mannich base is a versatile compound that can be easily modified to introduce different functional groups, allowing for the creation diverse selection of items with varying features. Additionally, the Mannich reaction is a valuable tool in organic synthesis, due to the fact it provides an effortless and efficient approach for synthesizing C-N bonds. Overall, The Mannich base and even its derivatives are essential in many aspects of chemistry and its complexes are in the pharmaceutical industry. Studies have revealed that it shows good anti-cancer, anti-mycobacterial, remarkable anti-HIV, anti-tubercular, anti-convulsant, anti-fungal, antiviral, antitumor, cytotoxic activities and in industrial applications such as in the creation of polymer
... Show MoreIn this study, the thermal buckling behavior of composite laminate plates cross-ply and angle-ply all edged simply supported subjected to a uniform temperature field is investigated, using a simple trigonometric shear deformation theory. Four unknown variables are involved in the theory, and satisfied the zero traction boundary condition on the surface without using shear correction factors, Hamilton's principle is used to derive equations of motion depending on a Simple Four Variable Plate Theory for cross-ply and angle-ply, and then solved through Navier's double trigonometric sequence, to obtain critical buckling temperature for laminated composite plates. Effect of changing some design parameters such as, ortho
... Show MoreIn general, path-planning problem is one of most important task in the field of robotics. This paper describes the path-planning problem of mobile robot based on various metaheuristic algorithms. The suitable collision free path of a robot must satisfies certain optimization criteria such as feasibility, minimum path length, safety and smoothness and so on. In this research, various three approaches namely, PSO, Firefly and proposed hybrid FFCPSO are applied in static, known environment to solve the global path-planning problem in three cases. The first case used single mobile robot, the second case used three independent mobile robots and the third case applied three follow up mobile robot. Simulation results, whi
... Show MoreTo investigate the prevalence of true periodontal chief complaints (CC) and the factors affecting their reporting by patients with periodontal diseases (PD).
This cross‐sectional study was based on retrospective analysis of available periodontal records. Different personal and demographic variables were obtained from these records including CC, age, gender, working status, past medical/dental history, smoking status and diagnosis. In addition, clinical parameters of plaque index, gingival index, probing pocket depth (PPD), and number of missing teeth. Periodontal CC were r
An analytical model in the form of a hyperbolic function has been suggested for the axial potential distribution of an electrostatic einzel lens. With the aid of this hyperbolic model the relative optical parameters have been computed and investigated in detail as a function of the electrodes voltage ratio for various trajectories of an accelerated charged-particles beam. The electrodes voltage ratio covered a wide range where the lens may be operated at accelerating and decelerating modes. The results have shown that the proposed hyperbolic field has the advantages of producing low aberrations under various magnification conditions and operational modes. The electrodes profile and their three-dimensional diagram have been determined whi
... Show MoreIsatin is a heterocyclic molecule that belongs to one of the most important classes of organic compounds known as indolines. Isatin, isatin analogs, and their Schiff bases have recently attracted a lot of attention in medicinal chemistry. Isatin, itself, shows various biological activities such as antiviral, anticancer, antimicrobial, anti-inflammatory, analgesic, antioxidant, and anticonvulsant. Bis- Schiff bases containing isatin moiety have been known to possess a wide spectrum of pharmacological activities. This review offers up-to-date information on the most active isatin bis-Schiff bases, which would include anticancer, antimicrobial, antiviral, anticonvulsant, anti-inflammatory, and analgesic activities. These observations c
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