Hassan Fawzy Elattar

Automotive air conditioning (AAC) systems traditionally use high-GWP refrigerants, raising environmental concerns. To address this, new azeotropic refrigerant blends, R513A, R513B, R515A, R515B, and R516A, have been developed. These blends offer environmentally friendly alternatives with promising thermodynamic performance. The R513A and R513B are suitable replacements for R1234yf and R134a with minimal system modifications, while R516A provides the highest cooling capacity (16.54 kW) and maximum optimal COP (39.84), making it highly effective. The R515A ensures low GWP and compressor temperatures, whereas R513A and R513B optimize energy efficiency and safety. Notably, R513A and R513B exhibit the lowest compression ratio, ?, and highest COP values (5.79, 7.23, and 9.40) across various evaporator temperatures, making them ideal for energy-saving applications. Overall, azeotropic refrigerants outperform R1234yf in COP, cooling capacity, and safety, while offering environmentally sustainable solutions for AAC.

This investigation attempts to develop a tower solar collector-based system designed for the cogeneration of cooling and desalination. The traditional organic Rankine cycle (ORC) integrated with the ejector refrigeration cycle generates limited power and cooling at a single temperature. Acknowledging their limitations, our present study uses an organic flash cycle (OFC) supported by solar heat combined with the two-phase ejector cycle and the reverse osmosis (RO) desalination unit. Since the OFC turbine is fed with two extra streams of fluid, therefore, it provides greater power to run the compressor of the ejector and pumps of the RO unit, resulting in the production of cooling at two different temperatures (refrigeration and air conditioning) and a higher mass flow rate of fresh water. A mathematical model is employed to assess the impact of coil curvature ratio, Rib height, and direct normal irradiation (DNI) on the temperature of the collector’s oil outlet. ANSYS-FLUENT conducts numerical simulations through computational fluid dynamics (CFD) analysis. The results indicate an ultimate increase in oil outlet temperature of 45% as the DNI increased from 450 to 1000 W/m² at a curvature ratio of 0.095 when employing the 1st Rib. Further, a steady-state energy and exergy analysis is conducted to evaluate the performance of the proposed cogeneration, with different design parameters like DNI, coil curvature ratio, rib height, and OFC turbine inlet pressure. The energetic and exergetic efficiencies of the cogeneration system at DNI of 800 W/m² are obtained as 16.67% and 6.08%, respectively. Exergetic assessment of the overall system shows that 29.57% is the exergy produced as cooling exergy, and the exergy accompanied by freshwater, 68.13%, is the exergy destroyed, and 2.3% is the exergy loss. The solar collector exhibits the maximum exergy destruction, followed by the ejector and RO pumps. Integrating multiple technologies into a system with solar input enhances efficiency, energy sustainability, and environmental benefits.

The higher the process efficiency, the lower the fuel consumption, and the less impact carbon emissions have on the environment. The flow characteristics around brick settings are an important field of investigation to acquire control over the energy intake and production process. The current work is a numerical CFD investigation to demonstrate fluid flow characterization inside the cooling zone in a brick tunnel kiln for lattice settings (the number of bricks in each layer is identical). Four different lattice settings were examined, and three were validated with published experimental data (settings 1, 2 and 3). In the current study, the BSL κ-ω turbulent model agrees well with the published experimental results. The numerical investigation presents the flow characteristics through four different lattice brick settings (e.g., velocity vectors, velocity contours and streamlines) that could not be measured experimentally. The investigation also looks at the flow zones of the vortex formation upstream, downstream and through the brick column. It was discovered that for settings 1 and 11, the quick air flow in the wall channels is much greater than in the column channels. Setting 3 has a larger vortex formation region, whereas setting 1 has a weaker vortex than the other settings. The cooling of the lattice bricks in Setting 3 is superior to the cooling in the other settings.

Simulation and analysis of a turbulent free jet flame erupting into still air are done using computational fluid dynamics (CFD). Using 2D axisymmetric numerical modeling in ANSYS-Fluent 14.5. Three distinct kinds of gaseous fuels are used: methane, carbon monoxide, and Biogas (50 % CH4 and 50 % CO2). The effects of thermal radiation modeling utilizing the P-1 radiation model on the behavior of a free jet flame are investigated, and the impacts of air temperature and fuel velocity on the flame length are also provided. The findings demonstrated that the radiation modeling did not affect the temperature distribution and flame length for CO and Biogas (i.e., lower heating value fuels). Nevertheless, the air temperature and fuel kind considerably impact the flame behavior. While the fuel inlet velocity (i.e., burner power) does not affect the flame length. Additionally, free jet flame velocity and length numerical correlations considering radiation modeling are predicted and presented with allowable errors. A comparison with earlier experimental correlation proved successful, with a maximum error of ±9.4%.