scholarly journals TURBOVENTILIATORIŲ, VEIKIANČIŲ BE VĖJO SRAUTO, EKSPERIMENTINIS TYRIMAS / EXPERIMENTAL INVESTIGATION OF TURBOVENTILATORS OPERATING WITHOUT WIND FLOW

2018 ◽  
Vol 10 (0) ◽  
pp. 1-5
Author(s):  
Dovydas Rimdžius ◽  
Juozas Bielskus
Keyword(s):  
Experimental Investigation ◽  
Energy Demand ◽  
High Efficiency ◽  
Normal Operation ◽  
Wind Flow ◽  
Wind Speeds ◽  
Energy Technologies ◽  
Operation Conditions ◽  
Low Wind Speeds ◽  
Ventilation Systems

Fans used in modern buildings ventilation systems make up a large part of the building‘s total energy demand. In order to ensure proper air quality and high efficiency of ventilation systems, it is necessary to search new solutions. One of the possible ways is to use renewable energy technologies. Currently it is a widespread use of wind energy in turboventilators. Major part of previous researches are related to tests of different construction turboventilators, determination of their characteristics and analysis of results. However, assessment of the current researches situation indicates the lack of fundamental researches of air flows interaction processes impact to turboventilators efficiency. In addition, researchers on hybrid turboventilators still search for solutions to increase the ventilation functionality when there is not enough wind power for operation of these devices. In order to determine the significance of these processes in more detail, in the present study, two different types of turboventilators are experimentally tested in two different ways. In one case, their rotors are rotated by an additional source of energy, in another case they are tested under different wind speed conditions. The aim of research is to assess not only the characteristics of the testes devices under normal conditions, but also their ventilation potential without wind flow. The results of experimental investigation showed that under normal operation conditions of the device, a large part of the extracted air flow is impacted by rotor rotation and ejection phenomenon. Empirical equations and investigation results presented in the paper can be useful for comparing other experiments and improving the functionality of the device at low wind speeds. Santrauka Šiuolaikinių pastatų vėdinimo sistemose naudojami ventiliatoriai sudaro didelę dalį pastato bendrojo energijos poreikio. Siekiant užtikrinti tinkamą oro kokybę ir aukštą vėdinimo sistemų efektyvumą, būtina ieškoti naujų sprendimų. Vienas iš galimų būdų – atsinaujinančią energiją naudojančių technologijų taikymas. Šiuo metu plačiai paplitęs būdas naudoti vėjo energiją turboventiliatoriuose. Didžioji dalis ankstesniuose moksliniuose tyrimuose atliktų eksperimentų susiję su skirtingų konstrukcijų turboventiliatorių bandymais, jų charakteristikų nustatymu ir rezultatų palyginimu. Visgi, vertinant esamą mokslinių tyrimų situaciją, pastebima, jog trūksta fundamentalių tyrimų nagrinėjant oro srautų sąveikos procesų įtaką turboventiliatorių efektyvumui. Be to, atliekamuose tyrimuose su hibridiniais tokio tipo įrenginiais tebeieškoma sprendimų, kaip padidinti vėdinimo funkcionalumą, kai nepakanka vėjo srauto įrenginiui veikti. Siekiant detaliau nustatyti minėtų procesų svarbą, pristatomame tyrime dviem skirtingais metodais eksperimentiškai bandomi du skirtingo tipo turboventiliatoriai. Vienu atveju jų rotoriai sukami papildomu energijos šaltiniu, kitu atveju bandomi skirtingomis vėjo greičių sąlygomis. Tyrimų metu siekiama įvertinti ne tik bandomų įrenginių charakteristikas veikiant įprastomis sąlygomis, bet ir jų vėdinimo potencialą be vėjo srauto. Eksperimentinių tyrimų rezultatai parodė, jog įrenginiui veikiant įprastomis sąlygomis didelė dalis ištraukiamojo oro srauto veikiama rotorių sukimosi bei ežekcijos reiškinio. Straipsnyje pateiktos empirinės lygtys ir tyrimo rezultatai gali būti naudingi lyginant kitus eksperimentus bei tobulinant įrenginio funkcionalumą esant mažam vėjo greičiui.

scholarly journals Influence of near standing cylindrical structures on wind pressure distribution on the multispan roofs of halls

2020 ◽  
Vol 313 ◽  
pp. 00048
Author(s):  
Ivana Veghova ◽  
Olga Hubova
Keyword(s):  
Experimental Investigation ◽  
Pressure Distribution ◽  
Wind Pressure ◽  
Wind Flow ◽  
Cylindrical Structures ◽  
Turbulent Wind ◽  
Wind Speeds ◽  
Load Calculation ◽  
Conservative Values ◽  
Made In

This article deals with experimental investigation of a wind pressure distribution on multispan roofs of halls. The wind pressure distribution on the structures is an important parameter in terms of wind load calculation. For multispan roofs it is possible to find these values in Eurocode 1991-1-4, but without an influence of surrounding structures. The series of parametric wind tunnel studies was carried out in BLWT to investigate the effects of in-line standing cylinders near the hall. Measurements were made in turbulent wind flow for two reference wind speeds and varying wind directions. The experimentally obtained cpe values were compared with the conservative values in EN 1991-1-4 for multispan roofs.

scholarly journals Research on Static and Dynamic Characteristics of Shear Spring of the Vibrating Flip-Flow Screen

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1644
Author(s):  
Guofeng Zhao ◽  
Xinwen Wang ◽  
Chi Yu ◽  
Shucheng Liu ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
High Efficiency ◽  
Dynamic Stiffness ◽  
Test System ◽  
Normal Operation ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Operation Conditions ◽  
Shear Spring ◽  
Stiffness And Damping

The vibrating flip-flow screen (VFFS) is a high-efficiency device currently used for deep screening of moist fine-grained materials. During VFFS operation, the normal operation of the screen is affected by fatigue damage to the shear springs arranged symmetrically on both sides of the screen, leading to equipment failures and disruption production. In this paper, the shear spring’s static and dynamic characteristics in different operation conditions were studied using the INSTRON 8801 fatigue test system and Dynacell dynamic sensors. Using an experimental test of shear spring stiffness and damping coefficients, the effects of some factors, i.e., temperature, hardness, amplitude and frequency, were studied. The results show that the temperature of the shear spring on the left side of the flip-flow screen was higher than that of the right side (driving side). With an increase in temperature, the stiffness of the shear spring decreased. With the increase in amplitude, the dynamic stiffness decreased and the damping coefficients did not change; with the increase in frequency, the dynamic stiffness increased and the damping coefficient decreased. At the same amplitude, with the increase in hardness of the shear spring, the dynamic stiffness increased. Finally, the stiffness and damping coefficients of the shear spring before and after tearing were obviously reduced. These research results reveal the relationship of the characteristics of a shear spring with operational conditions, and could provide a theoretical reference for the design of the VFFS and the selection of the shear spring.

scholarly journals Experimental Evaluation of Turbine Ventilators Performance under Different Test Conditions

2018 ◽  
Vol 64 ◽  
pp. 07003
Author(s):  
Rimdžius Dovydas ◽  
Bielskus Juozas ◽  
Martinaitis Vytautas ◽  
Motuzienė Violeta ◽  
Streckienė Giedrė
Keyword(s):  
Experimental Investigation ◽  
Major Part ◽  
Interaction Process ◽  
Normal Operation ◽  
Experimental Investigations ◽  
Empirical Equations ◽  
Air Flow Rate ◽  
Operation Conditions ◽  
Test Conditions ◽  
Main Construction

One of the most popular wind driven ventilation devices is a turbine ventilator. Its main construction components usually are air suction duct and impeller. However, there are many different configurations of such devices – different shape of vanes and ratios between main dimensions. In order to develop turbine ventilators there is demand for deeper fundamental researches. Major part of previous experimental investigations compares turbine ventilators performance. The aim of presented experimental investigation is to understand key parameters affecting wind driven ventilators performance. For this purpose, straight and curved vane devices under 4 different test conditions are tested. All tests are performed in modified wind tunnel based on the following methodology: 1) testing devices under normal operation conditions; 2) testing without impeller; 3) testing while impeller is stopped; 4) testing while air suction duct is sealed. Experimental results have shown that the biggest part of extracted air flow rate is impacted due to ejection of wind and air suction duct interaction process. A slight increase in performance of turbine ventilators compared to open duct column has been confirmed. Experiments also revealed differences between tested turbine ventilators rotational speed trends. Presented empirical equations of experiments could be used for design of turbine ventilators or other researches purposes.

scholarly journals Improving the efficiency of autonomous wind turbines

2021 ◽  
Vol 279 ◽  
pp. 01023
Author(s):  
Olga Pchelnikova-Grotova
Keyword(s):  
Mathematical Model ◽  
Power Plant ◽  
Wind Turbines ◽  
Power Plants ◽  
Wind Power Plant ◽  
Wind Flow ◽  
Utilization Factor ◽  
Wind Speeds ◽  
Operating Modes ◽  
Low Wind Speeds

The article discusses the development of a mathematical model of a combined wind turbine of a multi-modular wind power plant, which makes it possible to control the operation of wind turbines with the greatest efficiency, changing the operating modes of the installation depending on the wind flow entering the inlet. The implementation of the developed model at a multi-module wind station allowed us to obtain a maximum wind utilization factor of 0.35-0.47 at any wind speeds, as well as at low wind speeds to increase the initial torque of the wind wheel by 4 times in comparison with typical power plants.

SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

2018 ◽  
pp. 28-50
Author(s):  
S. G. Ignatiev ◽  
S. V. Kiseleva
Keyword(s):  
Energy Storage ◽  
Wind Speed ◽  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Energy Demand ◽  
Diesel Generator ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

scholarly journals Canard optimization for enhancing the performance of small horizontal axis wind turbine at low wind speeds

2020 ◽  
Vol 37 ◽  
pp. 63-71
Author(s):  
Yui-Chuin Shiah ◽  
Chia Hsiang Chang ◽  
Yu-Jen Chen ◽  
Ankam Vinod Kumar Reddy
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Peak Performance ◽  
Small Scale ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Optimum Parameters ◽  
Low Wind Speeds

ABSTRACT Generally, the environmental wind speeds in urban areas are relatively low due to clustered buildings. At low wind speeds, an aerodynamic stall occurs near the blade roots of a horizontal axis wind turbine (HAWT), leading to decay of the power coefficient. The research targets to design canards with optimal parameters for a small-scale HAWT system operated at variable rotational speeds. The design was to enhance the performance by delaying the aerodynamic stall near blade roots of the HAWT to be operated at low wind speeds. For the optimal design of canards, flow fields of the sample blades with and without canards were both simulated and compared with the experimental data. With the verification of our simulations, Taguchi analyses were performed to seek the optimum parameters of canards. This study revealed that the peak performance of the optimized canard system operated at 540 rpm might be improved by ∼35%.

scholarly journals Iodine reduction for reproducible and high-performance perovskite solar cells and modules

2021 ◽  
Vol 7 (10) ◽  
pp. eabe8130
Author(s):  
Shangshang Chen ◽  
Xun Xiao ◽  
Hangyu Gu ◽  
Jinsong Huang
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Electronic Materials ◽  
Substantial Reduction ◽  
Perovskite Solar Cells ◽  
High Yield ◽  
Operation Conditions ◽  
Record Value ◽  
Precursor Powders

Perovskite-based electronic materials and devices such as perovskite solar cells (PSCs) have notoriously bad reproducibility, which greatly impedes both fundamental understanding of their intrinsic properties and real-world applications. Here, we report that organic iodide perovskite precursors can be oxidized to I2 even for carefully sealed precursor powders or solutions, which markedly deteriorates the performance and reproducibility of PSCs. Adding benzylhydrazine hydrochloride (BHC) as a reductant into degraded precursor solutions can effectively reduce the detrimental I2 back to I−, accompanied by a substantial reduction of I3−-induced charge traps in the films. BHC residuals in perovskite films further stabilize the PSCs under operation conditions. BHC improves the stabilized efficiency of the blade-coated p-i-n structure PSCs to a record value of 23.2% (22.62 ± 0.40% certified by National Renewable Energy Laboratory), and the high-efficiency devices have a very high yield. A stabilized aperture efficiency of 18.2% is also achieved on a 35.8-cm2 mini-module.

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