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Go to Editorial ManagerThe depleting of the conventional sources of energy and the excess use of HCF components lead to the need for new techniques both for conservation of energy sources for the future and for decreasing the its harmful effects on the environment. This study investigated the adsorption capabilities of activated carbon. The adsorption of methanol on this substance was tested for their application in the adsorption refrigeration system based on solar energy._x000D_ Adsorption refrigeration system has been designed and manufactured with the energy source being solar energy. Methanol/activated carbon pairs have been used in experiments. The present work focused on the performance of the adsorption refrigeration system considering the temperature attained in the evaporator and the cooled spaced cabinet. The amounts of activated carbon used was (8 kg), while the amount of methanol were (1, 1.25, and 1.5) kg. The experiments were done in different days of the year. The amount of adsorption of methanol (as a result of decreasing the evaporator and cooled spaced temperature) was found to depend on the generator pressure and its increase as the primary generator pressure decreases. The best mass of methanol used was (1 kg) which give the lowest temperature obtained at the evaporative surface was ( 3.4 oC ) at the day ( 4/4/2017 ). The results shown that even in cloudy days there is a benefit from using such a system because the temperature attained is enough to start the adsorption process. The lowest temperature obtained at the evaporative surface was (3.4 oC) at the day (4/4/2017) for methanol mass of (1 kg) at an opening time of the valve between the evaporator and the generator (9:30am). The increase of methanol amount used in the experiment led to a good decrease in temperature attained in cooled spaced, but this is related to the time of connecting the evaporator and generator.
Functionally graded materials (FGM) are a category of composite materials distinguished by specific design attributes that allow them to serve various purposes and applications. This study used FGM samples made from carbon particles and a polyester matrix to manufacture micro-shapes and study the changes in vibration characteristics at different parameters. The manufactured samples contained different weight percentages, ranging from 0% to 20%, and a subsequent step involved manufacturing two different grades of FGM samples: one consisting of five layers and the other of eleven layers. The free vibration characteristics of the FGM structure were determined experimentally and numerically. The effect of varying several parameters on the natural frequency was monitored, including the number of FGM layers, thickness, and gradient coefficient. The Ansys Workbench (version 2022 R1) was used to analyze free vibration to verify the experimental results. Vibration testing of square FGM panels showed that the natural frequency increased with the number of layers. Improving the thickness of the panels also resulted in increased natural frequency values, when changing the thickness from 5mm to 10mm increases the natural frequency by an amount of 173.34 Hz at 11 layers. Model analysis using finite element analysis (FEA) tools confirmed the validity of the experimental solution, with a maximum discrepancy of 9.72%. Based on numerical calculations, the natural frequency coefficient decreased with increasing power law index under different boundary conditions and increased with increasing number of constraints in the sample.
Mathematical and numerical study of finned tube air cooled condenser for air conditioning unit with two ton refrigeration capacity using R22 as a base fluid and R407C an alternative fluid was investigated. Different parameters were considered in this work, such as condensing pressure, ambient temperature and refrigerant mass flow. A comparison of performance between two condensers when using R22 and R407C were performed. A redesign the condenser operates with the R407C to operate with the same system that operates with R22. The result showed the same behavior for the two refrigerants, the condensers are possible to work with R407C for the same geometry and some modifications in the structure of heat exchange with the same air velocity. The proposed model was validated with the outputs from the test data given in literature papers, derived from air cooled condensers with different dimensions. The results exhibited an agreement with the experimental results with a percentage of compatibility ± 10%.