Glass Tempering Research Articles

Optimisation and numerical study of forced convection heat transfer design for glass tempered cooling grille

Conventional glass tempering equipment suffers from uneven cooling and low energy efficiency in its design and operation, which highlights the limitations of existing production technologies. There is relatively little previous work describing the heat transfer properties of tempered glass in actual production. In this study, a combination of numerical simulation and experimental testing is used to optimise the design of cooling air grille in glass tempering equipment. Firstly, the variation characteristics of glass surface temperature with cooling time in the physical tempering process were experimentally investigated. Subsequently, the structural design and optimisation of the air deflector plate in the cooling air grille are carried out. Finally, a coupled flow-thermal-solid numerical model of the cooling air grille is constructed based on the experimental conditions, and the effects of the four air pressure plate structures on the heat transfer efficiency and temperature uniformity in the quenching process are explored. The results demonstrated that the designed rectangular plate performs better than the conventional plate. Compared with the traditional plate, the designed rectangular plate can reduce the base temperature of the glass by 4.21 K, increase the heat transfer coefficient by 5.03 %, and increase the heat transfer rate by 2.13 %. In addition, the glass surface temperature inhomogeneity is reduced by 7.32 % by the rectangular plate. The proposed design offers an appropriate resolution for industrial applications. It also provides a solid foundation for advancements in tempered glass quality.

Breakage risk analysis during the glass tempering process based on fluid–structure interaction approach

Breakage risk analysis during the glass tempering process based on fluid–structure interaction approach

Optimization of glass spray tempering parameters based on response surface methodology and economic analysis

Glass curtain walls have gained significant popularity as building enclosure structures, owing to their exceptional performance. Consequently, it becomes imperative to reduce energy consumption during the glass tempering process to ensure sustainable development within the construction industry. In this study, an experimental design was conducted using the response surface methodology (RSM). The particle count and cooling energy consumption were selected as the response value, while the influencing factors included four process parameters, namely, the spray distance (H), mist load fraction (f), spray pressure (p), and final cooling temperature (Tz). The second order model fitting of the RSM was used to obtain the polynomial regression equation between each response and each factor. Under the optimized conditions of H = 200 mm, f = 1.03, p = 0.5 MPa, and Tz = 150 °C, the number of fractured glass particles was found to be 234, and the cooling energy consumption was 0.00048 kW·h. Further analysis indicated that under these spray conditions, the net present value was 523.90 k$, and the dynamic payback period was 1.1 years. Compared to traditional air-cooled tempering, spray tempering demonstrated superior economic performance.

Computational analysis of spray cooling heat transfer and Influential factors during glass tempering

The spray cooling and tempering technology has a series of advantages, such as improving the tempering quality and reducing energy consumption. In order to optimize the tempering technological parameters, it is necessary to accurately control the thermal history and temperature distribution of a hot glass surface during spray cooling. However, measuring the inner temperature of tempered glass proved challenging. The Euler-Lagrangian approach was utilized for simulating the process of spray cooling the glass surface. To validate the accuracy of model predictions, experimental studies were conducted on the tempering of glass by a single nozzle. The numerical outcomes exhibit strong correspondence with the experimental findings. Building upon the foundation, the study analyzed the heat transfer mechanisms in different states including film boiling, nucleate boiling, and forced convection. Subsequently, the effects of spray distance, spray loading fraction, spray pressure, and final cooling temperature on the heat transfer rate and temperature homogeneity were discussed. The results revealed that reducing the spray distance, increasing the spray loading fraction and spray pressure can improve the cooling rate and reduce energy consumption, but it aggravated the uneven distribution of temperature over the glass surface. Moderately increasing the final cooling temperature had little effect on the tempering quality of glass, but it significantly reduced the energy consumption for spray cooling. Within the experimental range, the optimal final cooling temperature was 573.15 K.

Analysis of the effect of jet channel structure on the temperature uniformity of tempered glass

The air jet nozzle structure has a significant impact on the heat transfer uniformity and cooling rate of glass during the glass tempering process, and there is a lack of research on the discrepancy of different jet structures. The effects of double air knife, single air knife structures, and air hole structures on the cooling performance of glass in air-cooled tempering were investigated using numerical simulation and simplified analytical models. The calculated results are in agreement with the experimental results. The results show that the DK structure has a significant effect on improving the overall heat exchange performance of the glass, with lower surface temperatures for the same quenching time. The temperature inhomogeneities of DK, SK, and AH structures in the glass axial direction were 2.09%, 2.53%, and 3.33%, respectively, and the heat transfer uniformity of the DK structure was significantly better than the latter two. In comparison to the AH structure, the average heat transfer coefficients of the DK and SK structures increased by approximately 17.82% and 8.13%, respectively, while the heat transfer rates increased by approximately 7.05% and 4.51%. The study further improves the insufficiency of glass tempering research and provides theoretical guidance for the actual production of tempered glass.

Optimum geometry of some heat exchangers

Heat exchangers are present in our daily living and industrial applications. The size scale of heat exchangers is very large ranging from very small chips in electronics to huge equipment in process and energy industry. In the paper optimization approaches of some industrial examples are given. The goal is to present how analytical results can and must be used in multi-objective optimization of applications. The details of equations are not given due to page limits but they are found in the literature. The main goal is to show how numerical, analytical and optimization methods can be and must be combined in optimization of exchanger design and performance. The performance depends on very many factors and contradictory requirements must take into account such as maximization of heat transfer and simultaneously minimize for example the weight and size. Modifications of four existing applications are component placement on a wiring board, optimization of heat sink in power electronics, quality control in a glass tempering and optimization of a very huge heat exchanger called economizer in a recovery boiler.

AI and the transformation of industrial work: Hybrid intelligence vs double-black box effect

It is uncertain how the application of artificial intelligence (AI) technology transforms industrial work. We address this question from the perspective of cognitive systems, which, in this case, includes considerations of AI and process transparency, resilience, division of labor, and worker skills. We draw from a case study on glass tempering that includes a machine-vision-based quality control system and an advanced automation process control system. Based on task analysis and background literature, we develop the concept of hybrid intelligence that implies balanced AI transparency that supports upskilling and resilience. So-called fragmented intelligence, in turn, may result from the combination of the complexity of advanced automation along with the complexity of the process physics that places critical emphasis on expert knowledge. This combination can result in the so-called “double black box effect”, given that designing for understandability for the line workers might not be feasible: expert networks are needed for resilience.

Aircraft Cockpit Window Improvements Enabled by High-Strength Tempered Glass

<div>This research was initiated with the goal of developing a significantly stronger aircraft transparency design that would reduce transparency failures from bird strikes. The objective of this research is to demonstrate the fact that incorporating high-strength tempered glass into cockpit window constructions for commercial aircraft can produce enhanced safety protection from bird strikes and weight savings. Thermal glass tempering technology was developed that advances the state of the art for high-strength tempered glass, producing 28 to 36% higher tempered strength.</div> <div>As part of this research, glass probability of failure prediction methodology was introduced for determining the performance of transparencies from simulated bird impact loading. Data used in the failure calculation include the total performance strength of highly tempered glass derived from the basic strength of the glass, the temper level, the time duration of the load, and the area under load.</div> <div>A high-strength transparency construction developed using advanced technology tempered glass could produce significant weight saving estimated at 28% for a typical Boeing 737 jetliner window, or about 11.5 kg for the four windows of the Boeing 737 flight deck.</div> <div>The conclusions from the principals developed in this research for an advanced transparency construction including a 0.378-in. thick high-strength core ply could reduce the probability of failure from bird strike loading from 4,503 to 953 parts-per-million (PPM). A 0.500-in. thick high-strength standard thickness core ply could reduce the probability of failure from bird strike loading from 4,503 to 1.7 PPM.</div>

Coupled fluid-thermal-structural analysis during the air cooling for glass tempering

The tempering process of plate glass involves rapidly cooling the high-temperature glass using an array of impinging air jets, inducing desired stress during cooling. Consequently, the formation of tempering stress results from the coupled interaction among flow, heat transfer, and stress. However, most previous studies have commonly neglected the influence of the flow field by assuming a uniform and constant distribution of heat transfer coefficients at different positions on the glass plate, which deviates from actual situations. This study employed a fluid-thermal-structural coupled simulation approach to predict the non-uniform residual stress distribution in tempered glass and investigate the interaction mechanisms among flow, heat transfer, and stress. Simultaneously, to validate the reliability of the method and model, this study experimentally investigated the single-nozzle jet impingement cooling for glass tempering. The study concluded that the simulation results were consistent with the experiment. Subsequently, a comparative analysis was performed between the fluid-thermal-structural coupled simulation results based on real boundary conditions and the thermal-structural coupled simulation results based on ideal uniform heat transfer coefficient boundary conditions. The results revealed non-uniform distributions of both heat transfer coefficient and temperature due to varying localized flow characteristics. Consequently, the ratio of surface compressive stress to internal tensile stress along the width direction of the glass was not a fixed value but ranged from 1.63 to 2.38. Furthermore, significant differences were observed in the stress distribution under the simulations of fluid-thermal-structural coupling and thermal-structural coupling. Therefore, it is recommended to employ the fluid-thermal-structural coupling method when predicting localized stress distribution.

Modelling the Reliability of Logistics Flows in a Complex Production System

This paper analyses the disruptions occurring in a production system determining the operating states of a single machine. A system with a convergent production character, in which both single flows (streams) and multi-stream flows occur, was considered. In this paper, a two-level formalisation of the production system (PS) was made according to complex systems theory. The continuity analysis was performed at the operational level (manufacturing machine level). The definition of the kth survival value and the quasi-coherence property defined on chains of synchronous relations were used to determine the impact of interruption of the processed material flow on uninterrupted machine operation. The developed methodology is presented in terms of shaping the energy efficiency of technical objects with the highest power demand (the furnace of an automatic paint shop and the furnace of a glass tempering line were taken into consideration). The proposed methodology is used to optimise energy consumption in complex production structures. The model presented is utilitarian in nature—it can be applied to any technical system where there is randomness of task execution times and randomness of unplanned events. This paper considers the case in which two mutually independent random variables determining the duration of correct operation TP and the duration of breakdown TB are determined by a given distribution: Gaussian and Gamma family distributions (including combinations of exponential and Erlang distributions). A formalised methodology is also developed to determine the stability of system operation, as well as to assess the potential risk for arbitrary system evaluation parameters.

Analysis of the influence of deflector shape on heat transfer rate in glass tempering process

To solve the problem of uneven cold air flow during the tempering process, which causes glass self-detonation, distortion, and excessive fan energy consumption. Three deflector-shaped structures are proposed to enhance the cooling efficiency of the glass. Based on the combination of fluent numerical analysis and experiment, this study gives an in-depth examination of the heat transference of glass within a quenching system. The influence of deflector shapes on the heat transfer efficiency of glass is explored. The three deflectors were compared with traditional deflectors in terms of temperature, fluid flow, total heat transfer rate, and heat transfer coefficient. The simulation results agree well with the experimental data, and the established model of the glass quenching system is reliable. The rectangular deflectors reduce the glass base temperature by 3.03 K compared to traditional deflectors. Furthermore, when the rectangular deflectors are utilized, the maximum heat transfer coefficient of the glass can be up to 96.4 W/(m2·K) and the maximum total heat transfer can be up to 2622.82 W. In comparison to the traditional deflector shape, the maximum heat transfer coefficient of the designed rectangular deflectors may be enhanced by 0.58% and the maximum total heat transfer by 0.37%. The proposed design provides a suitable solution for the optimization of the tempering process as well as for the energy savings and efficiency of tempering equipment.

Robust transparent superhydrophilic antifogging coatings on glass substrates by a facile rapid thermal process

In this study, a rapid thermal process, which can be achieved via the conventional glass tempering process, was utilized to fabricate silica-based superhydrophilic antifogging coatings with micro-nano hierarchical roughness on glass substrates. The effects of SiO2 nanoparticle and triethylborate loadings on the coatings’ properties have been systematically investigated. Moreover, the formation mechanism of such coatings has been explained. The optimal coatings demonstrate a high level of hydrophilicity with a water contact angle (WCA) of ∼ 0°. Meanwhile, such coatings exhibit good antifogging effect and robustness as well.

Investigation on Circular Array of Turbulent Impinging Round Jets at Confined Case: A CFD Study

Jet impingement has immense applications in industrial cooling, such as glass tempering, turbine blades, electrical equipment, etc. The interplay in-between several jet arrangements and the effect of swirl intensity require enormous study to achieve steady heat transfer. This paper numerically investigates an inline array of 25 circular confined swirling air jets impinging vertically on a flat surface. In this regard, three-dimensional simulations are executed using the finite volume method for a number of control parameters, such as Reynolds number (Re = 11600, 24600, and 35000), impinging distance (H/D = 0.25, 0.5, 1), swirl number (S = 0.3 and 0.75) and jet-to-jet separation distance (Z/D = 2.5), where, D is the nozzle diameter. Impinging pressure distribution, flow velocity, surface Nusselt number, and Reynolds stresses are investigated for different operating conditions. The results reveal that both the wall pressure and surface Nusselt number are comparatively uniform in the case of high swirl flow. Moreover, distinct heat transfer behavior is observed from the unconfined condition for high swirl flow in which the heat transfer is constant after a certain radial distance. The Reynolds normal stress adjacent to the nozzle exit is more rigorous than the downstream regions while Reynolds shear stress varies unpredictably along the radial direction. In addition, an estimated 102 % enhancement in average Nusselt number is observed for high swirl flow, at a Reynolds number increment from 11600 to 35000. This enhancement is evident by 23 % in terms of thermal performance factor. Besides, the average Nusselt number and thermal performance factor augmented by 19 % and 8 %, respectively, for an increased swirl intensity at low a Reynolds number (Re =11600).

Numerical methodology based on fluid-structure interaction to predict the residual stress distribution in glass tempering considering non-uniform cooling

In this paper a novel numerical methodology for calculating non-uniform residual stress distributions during the glass tempering process is presented. Tempering techniques lead to non-uniform heat transfer rates causing residual stress inhomogeneities, which consequently have a direct impact on the structural behaviour of components. Nevertheless, most works in the literature do not consider the influence of local flow phenomena during thermal calculations, resulting in non-representative residual stress distributions. In this context, a novel generalised methodology based on a fluid–structure interaction one-way approach to sequentially couple the thermal and mechanical fields is presented. In this way, the unsteady and non-uniform heat transfer rate is coupled with the Narayanaswamy model to predict the non-homogeneous residual stress pattern. The obtained numerical results for the analysed impinging jet array case are in good agreement both quantitatively and qualitatively, exhibiting an average error below 10% with respect to previous experimental investigations. Finally, efforts are made to reduce the computational time. Therefore, the proposed methodology proves to be an efficient tool for understanding the underlying mechanisms and predicting the residual stress distributions during glass tempering.

Spray cooling heat transfer during glass tempering process and influencing factors on the quality of tempered glass

Compared with traditional physical tempering methods, spray cooling method has a series of advantages, such as smaller energy consumption and better tempering quality. However, this technology has not reached a mature level. Present study experimentally investigated the spray cooling for glass tempering at high water/air mass flow ratios for the first time, which verified the feasibility of the spray cooling method. Based on the Eulerian-Lagrange method, a two-phase flow model was established to simulate the spraying cooling on heated glass surface. Both wall-jet and Lagrangian wall-film models were adopted to realize the conversion of several modes of heat transfer. A good agreement between the simulated and experimental temperature and wall film distributions supported the reliability of the established model. Subsequently, the spray cooling heat transfer was numerically studied, and the effects of spray distance, mist flow rate and glass thickness on the tempering quality and heat transfer performance were discussed. The results showed that a decrease in spray distance and an increase in mist flow rate and glass thickness obviously enhanced the temperature difference and quality of the tempered glass. Within the scope of the experiment, the optimum spray distance and mist flow rate were 272.5 mm and 6.94 × 10−4 kg/s, respectively.

Structure and Screech Tone of Radially Underexpanded Jet Emitted by Facing Cylinders

An underexpanded jet has typical shock-cell structure and strongly oscillates, its behavior being known to cause many industrial problems. An underexpanded jet radially issues from intake and exhaust valves of an internal combustion engine, a pressure control valve and so on. When a supersonic jet exhausted from a circular nozzle impinges on a flat plate, the wall jet formed on the plate often becomes underexpanded and spreads out radially. Such underexpanded impinging jet is one of models of supersonic jets on laser cutting process and glass tempering process. In this study, an underexpanded jet radially discharged from a circular slit nozzle, which consists of two cylinders, was experimentally examined for different nozzle pressure ratios and for different diameters of cylinder. Jet structure was analyzed by means of a visualization e.g. Schlieren method. A noise emitted from the jet was measured and the frequency of screech tone was analyzed. The experimental results were compared with those of a two dimensional jet issuing from a rectangular nozzle. Furthermore, a comparison of visualized sound waves with the screech tone frequency reveals that the sound source measured was in the vicinity of the end of the second cell and that the length of the second or third cell was one of the most important parameters to determine the frequency of the emitted screech tone.

A Study on Broad Band Noise Emitted from Underexpanded Radial Jet

This study focuses on a noise emitted from a radial underexpanded jet. The underexpanded jet is well known as one of supersonic jets and it is formed when the pressure ratio across a convergent nozzle is more than the critical value. The underexpanded jet has been used in many fields, such a propulsion of rocket, laser cutting and a glass tempering process. Such jet is exhausted from a circular nozzle. The expansion wave, the compression wave and the shock wave are periodically formed in the jet, which leads to quasi-periodical shock-cell structure. On the other hand, an underexpanded jet radially issues from intake and exhaust valves of an internal combustion engine and a pressure control valve. The radial underexpanded jet does not have the quasi- periodical shock-cell structure such as the jet from the circular nozzle, its cell length decreasing along jet axis. In this study, an underexpanded jet radially discharged from a circular slit nozzle, which consists of two circular tubes, is experimentally examined for different nozzle pressure ratios. The jet structure is visualized using Schlieren method and a noise emitted from the jet is measured. Typically, the shock associated broadband noise is analyzed and a relation between the jet structure and the radiation noise frequency is discussed. As a result, it is found that the broadband noise lies on lower frequency than a screech tone and that the 1st cell length plays an important role in broadband noise radiation.

Analysis and optimization for the process of glass tempering using autoclave

A mathematical analysis of the glass tempering process was carried out using an autoclave, varying the operating parameters of the system. It was found that the process time can be reduced by up to 3.23% by changing the resistance to 15Ω, but increasing the resistance more than this value would mean compromising the quality of the final product. Thus, it is advisable to make variations of the resistance between 10Ω and15Ω, which will allow the optimization of the process time and pressures without affecting the quality of the result.

Demand forecasting: proposal of a model for a glass tempering industry

The given article aims to evaluate different quantitative demand forecast methods through a case study on a glass tempering company. The analysis were held based on historical data series, which allowed the use of a part of this data for method application and another part for comparison and validation of the model`s results. The methods were compared based on obtaining the mean absolute error. In the studied company, the raw material request for the suppliers was made when new orders are ordered (pulled production). This method results in longer responsiveness, mainly due to the waiting time of raw material arrival. The application of those different demand forecasting models were analysed over three types of products on the tempered glass category, which represents a total volume of 65% of the company's costs. As a result, two methods were better adapted to the real data, providing absolute errors between 0.25 and 0.29. This given work showed that the application of the demand forecasting methods would reduce orders delivery time, what could lead to real gains to the analyzed company.

Fuzzy self-learning control of glass tempering and annealing temperature based on the optimised genetic big data analysis algorithm

The temperature control of glass tempering and annealing process has the problems of the time varying parameters and time lag characteristic. In order to solve this problem, this paper proposes a self-learning fuzzy controller based on improved genetic algorithm and big data analysis. The proposed algorithm can quickly search the global optimal factor by using the big data temperature. Thus the fuzzy control rules are perfected and corrected. The simulation results demonstrate that the proposed control algorithm is suitable for systems with time varying parameters and time lag characteristic.