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The Vertical Take-off and Landing (VTOL) unmanned aerial vehicles (UAVs) with the tilt-rotor mechanism also known as hybrid UAVs have a lot of challenges in designing and controlling concerning their use in harsh weather for surveillance and access to remote areas. This review paper presents a review of the preliminary design of hybrid aircraft and control systems. The tilt-rotor mechanism and tilt wings of a hybrid UAV are analyzed. The paper provides an outline of technical advances in UAVs in hybrid configuration concerning their constraint analysis, propulsion sizing, and design evaluation. Furthermore, the flight dynamics modeling is described with the control system and dynamics of the hybrid UAV. This paper lists various software for simulations and analysis such as SOLIDWORKS and CATIA for CAD modeling, MATLAB and SIMULINK for mathematical modeling and flight control, and XFLR5 for stability analysis of aerofoils, wings, and planes. In addition, certain control strategies are executed and scrutinized in terms of the theory, the linearity, and the implementation of the model.

This paper investigates the performance of four nano-refrigerants (CuO-R113a, Al2O3-R134a, ZnO-R152a, TiO2-R600a) in terms of coefficient of performance and compressor power consumption using a MATLAB-Simulink two-phase flow domain Vapor Compression Refrigeration cycle. The analyses are done for volume concentrations of 0.1%, 0.3%, and 0.5% of nanoparticles in the base refrigerants. The results are derived mathematically in the Simulink model. The thermophysical properties of base-refrigerants were derived using the NIST Chemistry webbook and various mathematical models were applied to base refrigerants to calculate the properties of nano-refrigerants. The interpolation of the Liquid-vapor region was done using MS Excel. It was found that nano-refrigerants have better heat transfer characteristics and showed the best performance at a lower optimum concentration of 0.1%. Nano-refrigerant combinations have been tested in real-time and model validations; inferences have been duly reported.

In this paper viability of the Nano-refrigerants as a replacement for conventional coolants in bringing down energy consumption and thereby contribute to the green economy has been reviewed. The influence of the % of nanoparticle concentration in thermal conductivity, heat transfer characteristics, and system performance in a refrigeration system is analysed. In this paper, the use of MHD and NEPCM were also discussed and reviewed for their useful impact in the field of nano refrigeration. Review analysis indicated that the maximum coefficient of performance, i.e., 18.75% of enhancement, was observed when the TiO2 nanoparticle was added to the R134a refrigerant. Whereas in the case of the power consumption, Al2O3/R134a gives a 27% reduction in power consumption compared to the conventional fluids. Energy-saving of Al2O3/R134a nano-refrigerant is more than 5 times and 80% more efficient compared to R134a/CuO. Similarly, Al2O3/R134a is 50% more efficient than R134a/SiO2 and 3.4% more efficient than R134a/TiO2. However, R134a/TiO2 exhibited a 54.7% increment in the value of COP compared to R134a/Al2O3. Also, R134a/TiO2 displayed 60% and 35.2% of increment in COP in contrast to R134a/CuO, R134a/SiO2 respectively. The analysis recommends R134a/TiO2 as the best nano-refrigerant as its COP is the highest of all with the energy savings on par with the Al2O3/R134a.