PERFORMANCE COMPARISON AND OUTDOOR MONITORING OF SMOOTH AND TEXTURED COVER GLASS FOR SOLAR MODULES OF UP 6 YEARS EXPOSED

Solar modules are being built with nearly the same configuration for decades now. The front is covered with a tempered glass pane. The performance of a PV module can be increased by the texturation of the front side. One of the major requirements for front cover glasses is their high optical transmission. One option to boost transmission is texturing the front surface in a similar manner to crystalline solar cell. Another advantage of a textured glass is the fact that the reflected light beam at normal incidence has a second chance of being transmitted to the solar cell. Furthemore, the texturation of front cover glass might collect more dust and soiling than a flat glass surface. Due to this concern, the soiling effect of module covered with textured cover Alberino P glass after long-term exposed will investigated in this work. The modules presented in this work have the same characteristics in STC (i.e short circuit current, open circuit voltage and maximum power point). Electroluminescence, I-V and P-V characteristic are the method used to detect faults on the PV module. The results show a loss of PV performance with textured cover glass is l,72% higher than the reference module in other hand the increase of serie resistance is also observed in both modules

Prediction and Analysis of the Thermal Performance of Composite Vacuum Glazing

In this paper, a prediction method of the heat transfer coefficient of composite vacuum glazing (CVG) is proposed. By analyzing the heat transfer process of CVG, the theoretical calculation formula for the heat transfer coefficient of CVG is established. CVG temperature variation under the test conditions specified in the national standard is simulated using ANSYS. The CVG heat transfer coefficient is calculated by combining the theoretical formula and simulation results. The simulation results are then verified by comparison to a physical experiment. The results show that the deviations between the experimental and predicted values are ≤3.8%, verifying the accuracy of the simulation results and proving that the model can be used in engineering practice. Furthermore, the effects of different coating positions on the heat transfer performance of CVG are studied. The results show that different coating positions have a significant impact on the heat transfer coefficient of CVG. The heat transfer coefficient is shown to be lowest to highest under the following conditions: when the Low-E coatings are located on both sides of the vacuum layer (2LC-V), followed by Low-E coatings on the side of glass pane II near the vacuum layer (1LC-V), Low-E coatings located on the side of glass pane I near insulating layer (1LC-I), and finally, when there are no Low-E coatings (NLC) on the glass panes. Overall, this model is an effective and accurate analysis method of the heat transfer coefficient.

Edge strength of core drilled and waterjet cut holes in architectural glass

In structural glass design, an often-applied connection is a bolted connection subjected to in-plane tensile loads. Traditionally, the hole in the glass pane is manufactured by core drilling and conical edge finishing. An alternative method is by waterjet cutting the holes, resulting in cylindrically shaped holes. This research compares the edge strength of core drilled and waterjet cut holes. It focuses on in-plane tensile tests and consists of an experimental part in combination with a numerical part. In the in-plane tensile tests, peak stresses occur perpendicular to the load direction. These stresses are found to be higher for waterjet cut holes (+ 13%) compared to core drilled holes. As a result, the characteristic ultimate load is lower for waterjet cut holes (− 16%). Furthermore, the influence of thermally toughening the glass is found to be more favourable for the characteristic ultimate load of specimens containing core drilled holes than it is for waterjet cut holes. Next to that, it was found that the ultimate load linearly increases with the panel thickness. Eccentric loading, caused by insufficient bushing material or rotation of the bolt, only slightly decreases the ultimate load, provided that no hard contact between bolt and glass occurs. In addition, coaxial double ring tests were performed in the hole area, showing that waterjet cut holes result in larger stresses near the hole edge than core drilled holes. Furthermore, waterjet cut holes are found not to be perfectly round, while drilled holes are. This un-roundness negatively influences the ultimate load and the stresses in the glass; the larger the extent of un-roundness, the higher the stresses and the lower the ultimate load. Also, the orientation of the un-round hole is of influence on the stresses and ultimate load for the tensile test. It is concluded that waterjet cut holes result in lower characteristic ultimate loads and higher stresses. Due to the different edge finishing, the ultimate load still is lower compared to core drilled holes, even if the waterjet cut holes are perfectly round.

Experimental tests and numerical simulations of ballistic impact on laminated glass

In this study, we investigate double-laminated glass plates under ballistic impact through experimental tests and numerical simulations. The experimental tests are used to determine the ballistic limit velocity and curve for the laminated glass targets, and to create a basis for comparison with numerical simulations. We tested two different glass pane configurations: (1) one double-laminated glass plate, and (2) two layers of double-laminated glass plates separated by an airgap. In the numerical study, we used finite element simulations that employed higher order elements and 3D node splitting to predict the residual velocities of the bullets in the experiments. Node splitting enabled modelling of fracture by element separation and was employed for the glass parts. The material and fracture models that we used for the glass and the PVB parts were simplified, but the numerical predictions proved to be in excellent agreement with the experimental results.

The effect of openings on stress distribution in glass beams – Dependence on a hole to beam’s edge distance

The paper defines the behaviour of simply supported monolithic glass beam consisting of only one layer glass pane with discontinuities created by four holes positioned symmetrically on the beam. Similar glass panes can be found in real constructions where they act as a beam supporting glazing, roofs or decks of nowadays very popular transparent pedestrian bridges. The main aim of this paper is to provide both experimental and numerical analysis of stress distribution alongside the beam with a focus on areas where peak stresses may occur. The areas of interest are specifically speaking around openings, around supports and in the areas where the forces are introduced to the beam. As Eurocode standards for structural glass are still in the process of codifying and most of the nowadays literature only provides suggested axial distance of holes and hole to pane edge distance based on the thickness of the glass pane. This paper will provide the future designers of glass load-bearing structures with a closer look at stress distribution around the mentioned area. It was essential to do parametric study in software using FEM to investigate as much as possible axial distances of openings without a significant increment in the total cost of the experiment.

Advanced computational methods of perpendicularly loaded laminated glass panes

Various examples of glass load bearing structures such as beams, columns, panes, or even stairs are used in a current architecture. For safety reasons, these members are mostly made of laminated glass. Polymeric interlayers are used for glass plates bonding and their shear stiffness, as a time-temperature dependent parameter, meaningly influences the response of the entire perpendicularly loaded laminated glass pane. Even though the shear stiffness of the interlayer is available, the exact stress-state analysis of the pane is rather challenging. This paper compares the results of perpendicularly loaded double laminated glass panes at various boundary conditions, calculated by current advanced analytical methods and by the draft of the European standard prEN 16612 to the numerical simulation performed in RFEM 5®. Important differences between these methods are illustrated. Futher recommendations for a design of these structures in practice are also provided.

Simulation Study of Low-Velocity Impact on Polyvinyl Butyral Laminated Glass Based on the Combined TCK-JH2 Model

In this paper, both experimental tests and numerical simulations of Polyvinyl Butyral (PVB) laminated glass pane under low-speed impact were carried out. In order to accurately predict the responses of annealed glass under low-speed impact, a constitutive model combined of the Taylor–Chen–Kuszmaul (TCK) model and the Johnson-Holmquist Ceramic (JH2) model is proposed. In order to describe the tensile damage characteristic of annealed glass, a rate-dependent TCK model is employed. The JH2 model is adopted when the glass material is under compression. The velocity and force of impactor, deflection of central point of glass pane, and the cracking pattern are studied to verify the combined TCK-JH2 model. Furthermore, the effects of the thickness of glass layer and PVB interlayer are investigated.

Determining 2D temperature field in flow boiling with the use of Trefftz functions

The paper proposes the use of Trefftz method to solve the triple coupled heat conduction problem in flow boiling of refrigerant in an asymmetrically heated minichannel. A mathematical model of heat transfer in a rectangular minichannel is suggested. Two sets of Trefftz functions were used to determine 2D temperature fields at a fluid flow in the minichannel tilted at a known angle. The procedure for the calculation of the liquid temperature was coupled with the process of determining temperature fields in two adjacent elements of the experimental stand with the minichannel, i.e. in the glass pane and the heating foil. Heat transfer in the glass, foil and liquid is described using various 2D differential equations with an adequate set of boundary conditions. Solving those equations led to the solving of the triple coupled heat conduction problem made up of one direct and two subsequent inverse problems. The results are presented as: (1) 2D temperature of the glass pane, the heating foil, the flowing liquid, (2) mean square errors between temperature approximations and selected boundary conditions, (3) the heat transfer coefficient versus the distance from the minichannel inlet.