نشریه یافته های نوین کاربردی و محاسباتی در سیستم های مکانیکی
سال یکم شماره 3 (پاییز 1400)

In this study, the flow field analysis and heat transfer of two-phase nanofluid flow in a parabolic solar collector with eccentric absorber and solid insulation have been investigated. The fluid used in this collector is nanofluid of water - Aluminium. The main aim of current study is to investigate the effect of using eccentric absorber system and solid insulation on the energy efficiency of linear parabolic collectors. For this purpose, energy efficiency has been measured and presented for different states (including ambient temperature, fluid inlet temperature, nanofluid volume fraction, nanoparticle diameter and geometric characteristics). The study is in turbulent flow regime and in order to model it, the k epsilon turbulence model has been used. In order to solve the survival equations, the finite volume method and the SIMPLE C algorithm have been used. Different optimal models are introduced in terms of having the highest energy efficiency, and the best model is determined. Based on obtained results, the highest energy efficiency in different Reynolds is related to the novel collector and two-phase model(TPM). In the next positions, respectively, are the novel collector and single-phase model(SPM), the basic collector and two-phase model, and at the end, the basic collector and single-phase model. It was also found that as the Reynolds number increases, all modes have an uptrend. The maximum amount of energy efficiency was for the novel collector and the two-phase model at Reynolds 15000, Which is equal to 68%. Also, the maximum energy efficiency for eccentricity 20 mm at Reynolds 15000, which is equal to 74.9%.

In the present study, two inhibitors, benzomidazole and methyl benzomidazole, were used to prevent corrosion of X70 micro-alloy steel in acidic environment in one molar of sulfuric acid. For this purpose, both inhibitors in different concentrations were investigated in order to find the best concentration, temperature and efficiency of weight loss tests, polarization and electrochemical impedance spectroscopy (EIS). The chemical composition of the sample was obtained by quantum test and the sample with dimensions of 100 × 50 × 10 mm was prepared in 20 pieces. Corrosion protection performance of inhibitors in 1 M sulfuric acid solution for weight loss test after 10 days of immersion and also in polarization and impedance tests using Auto Lab and Nova1.11 software were evaluated. . As a result, the best inhibitory efficiency of benzomidazole at a concentration of 600 ppm was equal to 37% and methyl benzomidazole at a concentration of 400 ppm equal to 30%, and in the combined state of these two solutions have the ability to increase corrosion efficiency up to 73%. As a result, both of these inhibitors showed practical ability to be used in industrial environments.

In this research, Hunt type 6-DOF parallel robot is optimized based on kinetostatic performance indices and the effect of geometrical parameters on these indices is investigated. For this purpose, structural and geometrical parameters of Hunt type parallel robot are introduced. in order to determine the relationship between joint angle values and end effector coordinates, inverse kinematic is obtained. Jacobian matrix is developed to map velocity from joint space to Cartesian space. Manipulability, force manipulability and condition number are considered as indices to evaluate the robot performance. By defining the fitness functions, constraints and boundaries of geometric parameters, the optimized parallel robot structure is obtained using the multi-objective bees algorithm. A set of robot geometric parameters is presented, each of which has the best performance based on one of the indices. Also, a robot with specific geometric parameters is selected, which is suitable based on almost all performance indices. Finally, the effect of end effector movement on robot performance is investigated.