Low starting torque is considered as one of the major drawbacks of Darrieus type vertical axis wind turbine (VAWT). Design optimization to overcome this problem by modifying the airfoil geometry has received great attention by the wind energy community. Moreover, efforts have been directed towards augmenting the power coefficient of the turbine. In the present work, the effect of employing slotted airfoil as turbine blade on the performance and starting characteristics has been investigated. The slot parameters; slot location, angle of inclination, and dimensions, were optimized for NACA 0018 airfoil which is commonly used in Darrieus turbines. The flow over the turbine was modelled using ANSYS-FLUENT code. The main observations of the present study show that the VAWT with slotted Airfoil (SA) has a lower optimum tip speed ratio (TSR) compared with the Baseline (BL) turbine. This is associated with the ability to generate higher torque at lower rotational speeds. The analysis of the aerodynamic behavior of the SA turbine shows that the airfoil slot delays the separation at high angles of attack, and therefore improves the torque and power coefficient at low TSR.

Numerical investigation of Darrieus wind turbine with slotted airfoil blades

Energy-saving owing to using PCM into buildings: Considering of hot and cold climate region

Effect of Twisted Fins on the Melting performance of PCM in a Latent Heat Thermal Energy Storage System in Vertical and Horizontal Orientations: Energy and Exergy Analysis

Air cooling has attracted extensive attention in the field of battery thermal management (BTMS). A comprehensive optimization scheme adding secondary outlets and baffle was proposed in this paper to improve the cooling performance of the BTMS. Computational fluid dynamics (CFD) was conducted to investigate the influences of the number and width of secondary outlets and baffles on the cooling performance of the BTMS. The effectiveness of CFD method was verified by the air cooling heat dissipation experiment of battery pack. Firstly, the effects of the number and width of the secondary outlets were discussed and optimized. The results showed that, comparing with the initial Z-type BTMS, the maximum temperature (T max ) and the maximum temperature difference (ΔT max ) were reduced by 1.84 °C (4.20%) and 3.66 °C (75%) after optimization, respectively. Then, based on the above optimization model, a baffle had been added in the cooling channel to further better the air volume distribution and enhance the cooling performance. Compared with the initial Z-type BTMS, T max of the optimum model was reduced by 2.17 °C (4.95%) and ΔT max was reduced by 4.49 °C (91.89%). It can be seen that the optimization method proposed in this paper could be used to design the BTMS for electric vehicle. • The number and width of secondary outlets affected cooling performance greatly. • The relative errors between experimental and simulation results were within 2.6%. • The baffle could greatly improve the airflow distribution in local cooling channels. • The maximum temperature was reduced by 2.17 °C (4.95%) after optimization. • The maximum temperature difference was reduced by 4.49 °C (91.89%) after optimization. 

Cooling performance optimization of air cooling lithium-ion battery thermal management system based on multiple secondary outlets and baffle

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Performance enhancement of phase change materials in triplex-tube latent heat energy storage system using novel fin configurations

The melting heat transfer characteristics of PCM were studied in different combined types of heat exchangers. The effect of combining two different bifurcation level fractal fins was considered for PCM melting heat transfer in a phase change heat exchanger. Based on fractal theory and enthalpy-porosity method, a PCM melting model of two-dimensional unsteady heat transfer was established in a combined fractal fin heat exchanger. The influences of some factors, such as combined types of fractal fins, bifurcation level, heat transfer area of the fins and the spacing of the fins, were discussed for the melting heat transfer process. The results show that the complete melting time of PCM in a combined fractal fin heat exchanger is reduced by 68% compared with the traditional fractal fin heat exchanger. The melting time shows decreasing first and then gradually stabilizing as the bifurcation level number and heat transfer area of the combined fractal fins increase. The melting rate of PCM is the fastest in the Case 4 heat exchanger, and the complete melting time of PCM is the shortest in the Case 3 heat exchanger. Fin spacing and heat transfer area have a significant impact on the complete melting time. On this basis, the thermal performance coefficients between the fins zone and PCM zone are defined. The complete melting time of PCM is found to be exponentially negatively correlated with the thermal performance coefficient by curve fitting. The temperature distribution uniformity coefficient is proposed to evaluate the temperature distribution uniformity during the melting process of PCM. It is found that the temperature distribution uniformity of Case 2 has the best at the end of melting. The above results provide a theoretical basis for structural design of the heat exchanger with combined fractal fins to enhance PCM melting heat transfer. 

Numerical study on enhanced melting heat transfer of PCM by the combined fractal fins

The main purpose of this paper is to demonstrate a bionic design for the airfoil of wind turbines inspired by the morphology of Long-eared Owl’s wings. Glauert Model was adopted to design the standard blade and the bionic blade, respectively. Numerical analysis method was utilized to study the aerodynamic characteristics of the airfoils as well as the blades. Results show that the bionic airfoil inspired by the airfoil at the 50% aspect ratio of the Long-eared Owl’s wing gives rise to a superior lift coefficient and stalling performance and thus can be beneficial to improving the performance of the wind turbine blade. Also, the efficiency of the bionic blade in wind turbine blades tests increases by 12% or above (up to 44%) compared to that of the standard blade. The reason lies in the bigger pressure difference between the upper and lower surface which can provide stronger lift.

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Bionic Design of Wind Turbine Blade Based on Long-Eared Owl’s Airfoil

Using image processing technology to study sugarcane image contour extraction and edge detection methods has important research value and practical application significance for realizing pre-seed sugarcane planter to complete the seeding task stably, quickly, accurately and efficiently. In this regard, with the help of the MATLAB platform, this paper uses the hollowing out internal point algorithm to achieve the contour extraction of the sugarcane image, and uses five more classic edge detection operators for the same original sugarcane image to realize the edge detection of the sugarcane image. Analyze the results and draw the conclusion that Canny operator is the most suitable and effective edge detection operator for sugarcane image edge detection. This also provides an important reference for subsequent monitoring of the seeding status and efficiency of the precut sugarcane planter.

Research on contour extraction and edge detection of sugarcane image based on MATLAB

In this study, a new wing plate was designed for the wave glider. The wing plate A and the wing plate C made of NACA0012 were extracted from the adult green sea turtle in the Pacific Ocean, and a new wing plate B was optimized by optimizing the design of the two, and set the control. Group wings D. In order to improve the utilization rate of wave energy of the wave glider, the hydrodynamic performance of the wave glider wing was studied. At the installation angle of 0-90°, the thrust FX in the forward direction of the four types of wings is simulated and calculated. The results show that at the angle of attack of 6° and 9°, the incoming flow velocity is 0.5m/s, 1m/s, 1.5 At m/s, the hydrodynamic performance of the wing plate increases with the increase of the installation angle. The hydrodynamic performance of the four kinds of wing plates is from good to bad: B-foil, A-foil, C-foil and D-foil. The research results help to understand the hydrodynamic performance of the wing plate, and provide a research basis for improving the wave energy utilization rate of the wave glider.

Jiyue Wang

Papers

Numerical study on enhanced melting heat transfer of PCM by the combined fractal fins

Bionic Design of Wind Turbine Blade Based on Long-Eared Owl’s Airfoil

Research on contour extraction and edge detection of sugarcane image based on MATLAB

Research on optimization of wave glider wing plate

A Novel Fusion Strategy and Convolutional Sparse Coding for Robot Multisource Image Fusion