scholarly journals Experimental investigation of the wind direction influence on the cooling of photovoltaic panels integrated in double skin façades

2019 ◽  
Vol 111 ◽  
pp. 03045
Author(s):  
Sebastian Valeriu Hudișteanu ◽  
Cătalin George Popovici
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Direction ◽  
Warm Season ◽  
Experimental Program ◽  
Small Scale ◽  
Transfer Coefficients ◽  
Photovoltaic Panels ◽  
Reference Velocity ◽  
Double Skin

The paper presents a wind tunnel experimental investigation of a small-scale building model (1:30). The main objective of the study is to determine the influence of the reference wind direction over the ventilation inside the double skin façade (DSF) channel. The analyzed system consists of a building equipped with photovoltaic panels as the exterior glazing of DSF. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The aim is to determine with acceptable probability the velocities that can be reached in the ventilated façade channel during the warm season and to establish a correlation between the external reference velocity magnitude and direction and the velocity field generated inside the channel of the façade. Measurements were carried out for the reference wind speed, total, dynamic and static pressure both in the reference point and inside the façade channel. The results of the investigation highlighted the correlation between the velocity and direction of the reference wind and the dynamics of the air movement inside the double skin façade. The measurements showed that for the analyzed configuration of the double skin façade, there is an optimal wind direction that ensures the best cooling effect to photovoltaic panels. Also, the convective heat transfer coefficients were determined under these conditions. The decrease of the photovoltaic panel’s temperature determines a raise of its efficiency and generated power.

scholarly journals Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

2018 ◽  
Vol 32 ◽  
pp. 01020 ◽  
Author(s):  
Sebastian Valeriu Hudişteanu ◽  
Cătălin George Popovici ◽  
Nelu-Cristian Cherecheş
Keyword(s):  
Wind Tunnel ◽  
Natural Ventilation ◽  
Cooling Effect ◽  
Experimental Program ◽  
Small Scale ◽  
Photovoltaic Panels ◽  
Building Integrated Photovoltaics ◽  
Building Model ◽  
Double Skin ◽  
Wind Influence

The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

Experimental investigation of the performance and wake effect of a small-scale wind turbine in a wind tunnel

Energy ◽  
2019 ◽  
Vol 166 ◽  
pp. 819-833 ◽  
Author(s):  
Bingzheng Dou ◽  
Michele Guala ◽  
Liping Lei ◽  
Pan Zeng
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Small Scale ◽  
Wake Effect

scholarly journals Experimental and analytical study of seismic site response of discontinuous permafrost

2016 ◽  
Vol 53 (9) ◽  
pp. 1363-1375 ◽  
Author(s):  
Behrang Dadfar ◽  
M. Hesham El Naggar ◽  
Miroslav Nastev
Keyword(s):  
Shear Wave ◽  
Site Response ◽  
Free Field ◽  
Frozen Soil ◽  
Shaking Table ◽  
Experimental Program ◽  
Small Scale ◽  
Seismic Site Response ◽  
Discontinuous Permafrost ◽  
Spectral Accelerations

Seismic site response of discontinuous permafrost is discussed. The presence of frozen ground in soil deposits can significantly affect their dynamic response due to stiffer conditions characterized by higher shear-wave velocities compared to unfrozen soils. Both experimental and numerical investigations were conducted to examine the problem. The experimental program included a series of 1g shaking table tests on small-scale models. Nonlinear numerical analyses were performed employing FLAC software. The numerical model was verified using the obtained experimental results. Parametric simulations were then conducted using the verified model to study variations of the free-field spectral accelerations (on top of the frozen and unfrozen soil blocks) with the scheme of frozen–unfrozen soil, and to determine the key parameters and their effects on seismic site response. Results show that spectral accelerations were generally higher in frozen soils than in unfrozen ones. It was found that the shear-wave velocity of the frozen soil as well as the assumed geometry of the blocks and their spacing have a significant impact on the site response.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

Wind Tunnel Tests of a Model Small-scale Horizontal-axis Wind Turbine Developed from Blade Element Momentum Theory

2021 ◽  
pp. 1-16
Author(s):  
Ojing Siram ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Tunnel ◽  
Horizontal Axis ◽  
Superior Performance ◽  
Speed Ratio ◽  
Small Scale ◽  
Blade Design ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Blade Element

Abstract The small-scale horizontal-axis wind turbines (SHAWTs) have emerged as the promising alternative energy resource for the off-grid electrical power generation. These turbines primarily operate at low Reynolds number, low wind speed, and low tip speed ratio conditions. Under such circumstances, the airfoil selection and blade design of a SHAWT becomes a challenging task. The present work puts forward the necessary steps starting from the aerofoil selection to the blade design and analysis by means of blade element momentum theory (BEMT) for the development of four model rotors composed of E216, SG6043, NACA63415, and NACA0012 airfoils. This analysis shows the superior performance of the model rotor with E216 airfoil in comparison to other three models. However, the subsequent wind tunnel study with the E216 model, a marginal drop in its performance due to mechanical losses has been observed.

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