The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Chengwang Lei - One of the best experts on this subject based on the ideXlab platform.
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A numerical investigation of combined solar chimney and water wall for building ventilation and thermal comfort
Building and Environment, 2020Co-Authors: Haoyu Wang, Chengwang LeiAbstract:Abstracts This paper reports a numerical investigation of combined solar chimney and water wall for building ventilation and thermal comfort. The effects of major design parameters including glass Panel Thickness, air gap width and water column Thickness are investigated with CFD simulations. The results show that the combined system is capable of providing around-the-clock ventilation with a daily average of 4.1 air changes per hour while maintaining the daily average of the room temperature 4.8 °C above that of the ambient. The overall performance of the combined system may be further improved by reducing the glass Panel Thickness or applying solar control tinting to the water wall assembly, and as much as 7.3% and 5.2% improvements in the ventilation rate and the averaged room temperature respectively can be achieved. Increasing the water column Thickness by 0.1 m leads to 4.9% or more improvement in the ventilation rate but will cause the averaged room temperature to drop by 6.4% when the water column Thickness is increased to 0.3 m. Increasing the air gap width from 0.1 m to 0.2 m leads to 13.9% improvement in the ventilation rate without affecting the averaged room temperature much. However, further increasing the air gap width only has a minor impact on the ventilation rate.
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Theoretical modeling of combined solar chimney and water wall for buildings
Energy and Buildings, 2019Co-Authors: Haoyu Wang, Chengwang LeiAbstract:Abstract In this paper, a combined solar chimney and water wall is proposed to provide ventilation as well as moderate heating to an attached room. A transient heat balance model (THBM) is established to predict the thermal performance of the combined system under mild winter conditions in Sydney, Australia. The effects of the glass Panel Thickness, air gap width, water column Thickness, surface tinting and the relative position of solar chimney and water wall are studied respectively. The results show that the combined solar chimney and water wall is capable of providing ventilation throughout the day and night while maintaining the warmth level of the room even though it continuously draws fresh air from the ambient into the room. It is found that increasing the glass Panel Thickness or reducing the water column Thickness enhances the thermal performance of the combined system by increasing both the room temperature and the ventilation rate. On the other hand, increasing the air gap width helps to increase the ventilation rate, but will cause the room temperature to decrease. In addition, between the two configurations, one with the water wall in front of the solar chimney (referred to as the WW-SC configuration) and the other with the solar chimney in front of the water wall (referred to as the SC-WW configuration), the ventilation rate and room temperature obtained with the SC-WW configuration are higher, and thus the latter configuration is more favorable. Furthermore, it is found that surface tinting generally degrades the thermal performance of the proposed system.
Haoyu Wang - One of the best experts on this subject based on the ideXlab platform.
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A numerical investigation of combined solar chimney and water wall for building ventilation and thermal comfort
Building and Environment, 2020Co-Authors: Haoyu Wang, Chengwang LeiAbstract:Abstracts This paper reports a numerical investigation of combined solar chimney and water wall for building ventilation and thermal comfort. The effects of major design parameters including glass Panel Thickness, air gap width and water column Thickness are investigated with CFD simulations. The results show that the combined system is capable of providing around-the-clock ventilation with a daily average of 4.1 air changes per hour while maintaining the daily average of the room temperature 4.8 °C above that of the ambient. The overall performance of the combined system may be further improved by reducing the glass Panel Thickness or applying solar control tinting to the water wall assembly, and as much as 7.3% and 5.2% improvements in the ventilation rate and the averaged room temperature respectively can be achieved. Increasing the water column Thickness by 0.1 m leads to 4.9% or more improvement in the ventilation rate but will cause the averaged room temperature to drop by 6.4% when the water column Thickness is increased to 0.3 m. Increasing the air gap width from 0.1 m to 0.2 m leads to 13.9% improvement in the ventilation rate without affecting the averaged room temperature much. However, further increasing the air gap width only has a minor impact on the ventilation rate.
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Theoretical modeling of combined solar chimney and water wall for buildings
Energy and Buildings, 2019Co-Authors: Haoyu Wang, Chengwang LeiAbstract:Abstract In this paper, a combined solar chimney and water wall is proposed to provide ventilation as well as moderate heating to an attached room. A transient heat balance model (THBM) is established to predict the thermal performance of the combined system under mild winter conditions in Sydney, Australia. The effects of the glass Panel Thickness, air gap width, water column Thickness, surface tinting and the relative position of solar chimney and water wall are studied respectively. The results show that the combined solar chimney and water wall is capable of providing ventilation throughout the day and night while maintaining the warmth level of the room even though it continuously draws fresh air from the ambient into the room. It is found that increasing the glass Panel Thickness or reducing the water column Thickness enhances the thermal performance of the combined system by increasing both the room temperature and the ventilation rate. On the other hand, increasing the air gap width helps to increase the ventilation rate, but will cause the room temperature to decrease. In addition, between the two configurations, one with the water wall in front of the solar chimney (referred to as the WW-SC configuration) and the other with the solar chimney in front of the water wall (referred to as the SC-WW configuration), the ventilation rate and room temperature obtained with the SC-WW configuration are higher, and thus the latter configuration is more favorable. Furthermore, it is found that surface tinting generally degrades the thermal performance of the proposed system.
Wuli Chu - One of the best experts on this subject based on the ideXlab platform.
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Vibroacoustic Optimization Study for the Volute Casing of a Centrifugal Fan
MDPI AG, 2019Co-Authors: Jianhua Zhang, Wuli Chu, Jinghui ZhangAbstract:A numerical optimization is presented to reduce the vibrational noise of a centrifugal fan volute. Minimal vibrational radiated sound power was considered as the aim of the optimization. Three separate parts of volute Panel Thickness (ST: the side Panel Thickness; BT: the back Panel Thickness; FT: the front Panel Thickness) were taken as the design variables. Then, a vibrational noise optimization control method for the volute casing was proposed that considered the influence of vibroacoustic coupling. The optimization method was mainly divided into three main parts. The first was based on the simulation of unsteady flow to the fan to obtain the vibrational noise source. The second used the design of experiments (DoE) method and a weighted-average surrogate model (radial basis function, or RBF) with three design variables related to the geometries of the three-part volute Panel Thickness, which was used to provide the basic mathematical model for the optimization of the next part. The third part, implementing the low vibrational noise optimization for the fan volute, applied single-objective (taking volute radiated acoustical power as the objective function) and multi-objective (taking the volute radiated acoustical power and volute total mass as the objective function) methods. In addition, the fan aerodynamic performance, volute casing surface fluctuations, and vibration response were validated by experiments, showing good agreement. The optimization results showed that the vibrational noise optimization method proposed in this study can effectively reduce the vibration noise of the fan, obtaining a maximum value of noise reduction of 7.3 dB. The optimization in this study provides an important technical reference for the design of low vibroacoustic volute centrifugal compressors and fans whose fluids should be strictly kept in the system without any leakage
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Vibro-Acoustic Optimization Study for the Volute Casing of a Centrifugal Fan
2018Co-Authors: Jianhua Zhang, Wuli Chu, Jinghui ZhangAbstract:Concerning fan systems with an air pipe connecting air intake and a closed outlet, aerodynamic noise cannot be directly transmitted from the fan inlet and outlet to the outside. At this moment, the volute vibrational radiation noise induced casing surface vibration is the major noise component. The main factors affecting the fan vibrational noise are analyzed through theoretical derivation, then a vibrational noise optimization control method for the volute casing is proposed that considered the influence of vibro-acoustic coupling, taking the Panel Thickness of the volute (front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) as design variables, and the acoustical power of the volute surface and the total mass of the volute as the optimal target function. The optimization method is mainly divided into three main parts: the first was based on the simulation of unsteady flow of the fan to obtain the vibrational noise source; the second, using the design of experimental (DOE) method and the proposed numerical simulation of fluid-structure-acoustic coupling method to obtain the designing space, then the radical-based function (RBF) method is used to construct the approximate surrogate model instead of the simulation model previously mentioned, which was used to provide the basic mathematical model for the optimization of the next part; the third part, implementing the low vibrational noise optimization for the fan volute, applied the single-target (taking volute radiated acoustical power as the target function) and the multi-target (taking the volute radiated acoustical power and volute total mass as the target function) methods. In addition, the fan aerodynamic performance, volute casing surface fluctuations, and vibration response were validated by experiments, showing good agreement. It is of utmost importance that the dynamic pressure measurements and vibrational tests on the volute casing verify the accuracy of the numerical calculation. The optimization results showed that the vibrational noise optimization method proposed in this study can effectively reduce the vibration noise of the fan, obtaining a maximum value of noise reduction of 7.3 dB. The optimization identified in this paper provides a significant reference for the design of a low-vibrational-noise volute.
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Parametric study of unsteady-flow-induced volute casing vibro-acoustics in a centrifugal fan
Vibroengineering PROCEDIA, 2018Co-Authors: Jianhua Zhang, Wuli ChuAbstract:A numerical parametric analysis of a vibro-acoustic coupling method that considered the influence of vibro-acoustic coupling was carried out to investigate the casing vibrations and feathers of vibrational noise induced by unsteady flow of the centrifugal fan at the best-efficiency point (BEP). There are three important aspects of this method. First, an unsteady flow-field with a whole impeller-volute configuration was solved based on three-dimensional incompressible Navier-Stokes equations and a standard k-e turbulence mode to obtain the source of the vibro-acoustics. Second, a one-way-flow structural acoustic coupling method was implemented to study the volute vibrations and behaviors of vibrational noise by adoption. The generation mechanism of vibrational noise of the volute casing was revealed. Third, the parametric analysis method was used to explore the parametric relationship between the Panel Thicknesses (such as front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) and the outlet acoustical power of the volute casing surface. The parametric analysis provides a reasonable range of values of three Panel Thicknesses that result in minimal vibrational sound radiation.
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Parametric study of unsteady-flow-induced volute casing vibro-acoustics in a centrifugal fan
'JVE International Ltd.', 2018Co-Authors: Jianhua Zhang, Wuli ChuAbstract:A numerical parametric analysis of a vibro-acoustic coupling method that considered the influence of vibro-acoustic coupling was carried out to investigate the casing vibrations and feathers of vibrational noise induced by unsteady flow of the centrifugal fan at the best-efficiency point (BEP). There are three important aspects of this method. First, an unsteady flow-field with a whole impeller-volute configuration was solved based on three-dimensional incompressible Navier-Stokes equations and a standard k-ε turbulence mode to obtain the source of the vibro-acoustics. Second, a one-way-flow structural acoustic coupling method was implemented to study the volute vibrations and behaviors of vibrational noise by adoption. The generation mechanism of vibrational noise of the volute casing was revealed. Third, the parametric analysis method was used to explore the parametric relationship between the Panel Thicknesses (such as front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) and the outlet acoustical power of the volute casing surface. The parametric analysis provides a reasonable range of values of three Panel Thicknesses that result in minimal vibrational sound radiation
Jianhua Zhang - One of the best experts on this subject based on the ideXlab platform.
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Vibroacoustic Optimization Study for the Volute Casing of a Centrifugal Fan
MDPI AG, 2019Co-Authors: Jianhua Zhang, Wuli Chu, Jinghui ZhangAbstract:A numerical optimization is presented to reduce the vibrational noise of a centrifugal fan volute. Minimal vibrational radiated sound power was considered as the aim of the optimization. Three separate parts of volute Panel Thickness (ST: the side Panel Thickness; BT: the back Panel Thickness; FT: the front Panel Thickness) were taken as the design variables. Then, a vibrational noise optimization control method for the volute casing was proposed that considered the influence of vibroacoustic coupling. The optimization method was mainly divided into three main parts. The first was based on the simulation of unsteady flow to the fan to obtain the vibrational noise source. The second used the design of experiments (DoE) method and a weighted-average surrogate model (radial basis function, or RBF) with three design variables related to the geometries of the three-part volute Panel Thickness, which was used to provide the basic mathematical model for the optimization of the next part. The third part, implementing the low vibrational noise optimization for the fan volute, applied single-objective (taking volute radiated acoustical power as the objective function) and multi-objective (taking the volute radiated acoustical power and volute total mass as the objective function) methods. In addition, the fan aerodynamic performance, volute casing surface fluctuations, and vibration response were validated by experiments, showing good agreement. The optimization results showed that the vibrational noise optimization method proposed in this study can effectively reduce the vibration noise of the fan, obtaining a maximum value of noise reduction of 7.3 dB. The optimization in this study provides an important technical reference for the design of low vibroacoustic volute centrifugal compressors and fans whose fluids should be strictly kept in the system without any leakage
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Vibro-Acoustic Optimization Study for the Volute Casing of a Centrifugal Fan
2018Co-Authors: Jianhua Zhang, Wuli Chu, Jinghui ZhangAbstract:Concerning fan systems with an air pipe connecting air intake and a closed outlet, aerodynamic noise cannot be directly transmitted from the fan inlet and outlet to the outside. At this moment, the volute vibrational radiation noise induced casing surface vibration is the major noise component. The main factors affecting the fan vibrational noise are analyzed through theoretical derivation, then a vibrational noise optimization control method for the volute casing is proposed that considered the influence of vibro-acoustic coupling, taking the Panel Thickness of the volute (front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) as design variables, and the acoustical power of the volute surface and the total mass of the volute as the optimal target function. The optimization method is mainly divided into three main parts: the first was based on the simulation of unsteady flow of the fan to obtain the vibrational noise source; the second, using the design of experimental (DOE) method and the proposed numerical simulation of fluid-structure-acoustic coupling method to obtain the designing space, then the radical-based function (RBF) method is used to construct the approximate surrogate model instead of the simulation model previously mentioned, which was used to provide the basic mathematical model for the optimization of the next part; the third part, implementing the low vibrational noise optimization for the fan volute, applied the single-target (taking volute radiated acoustical power as the target function) and the multi-target (taking the volute radiated acoustical power and volute total mass as the target function) methods. In addition, the fan aerodynamic performance, volute casing surface fluctuations, and vibration response were validated by experiments, showing good agreement. It is of utmost importance that the dynamic pressure measurements and vibrational tests on the volute casing verify the accuracy of the numerical calculation. The optimization results showed that the vibrational noise optimization method proposed in this study can effectively reduce the vibration noise of the fan, obtaining a maximum value of noise reduction of 7.3 dB. The optimization identified in this paper provides a significant reference for the design of a low-vibrational-noise volute.
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Parametric study of unsteady-flow-induced volute casing vibro-acoustics in a centrifugal fan
Vibroengineering PROCEDIA, 2018Co-Authors: Jianhua Zhang, Wuli ChuAbstract:A numerical parametric analysis of a vibro-acoustic coupling method that considered the influence of vibro-acoustic coupling was carried out to investigate the casing vibrations and feathers of vibrational noise induced by unsteady flow of the centrifugal fan at the best-efficiency point (BEP). There are three important aspects of this method. First, an unsteady flow-field with a whole impeller-volute configuration was solved based on three-dimensional incompressible Navier-Stokes equations and a standard k-e turbulence mode to obtain the source of the vibro-acoustics. Second, a one-way-flow structural acoustic coupling method was implemented to study the volute vibrations and behaviors of vibrational noise by adoption. The generation mechanism of vibrational noise of the volute casing was revealed. Third, the parametric analysis method was used to explore the parametric relationship between the Panel Thicknesses (such as front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) and the outlet acoustical power of the volute casing surface. The parametric analysis provides a reasonable range of values of three Panel Thicknesses that result in minimal vibrational sound radiation.
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Parametric study of unsteady-flow-induced volute casing vibro-acoustics in a centrifugal fan
'JVE International Ltd.', 2018Co-Authors: Jianhua Zhang, Wuli ChuAbstract:A numerical parametric analysis of a vibro-acoustic coupling method that considered the influence of vibro-acoustic coupling was carried out to investigate the casing vibrations and feathers of vibrational noise induced by unsteady flow of the centrifugal fan at the best-efficiency point (BEP). There are three important aspects of this method. First, an unsteady flow-field with a whole impeller-volute configuration was solved based on three-dimensional incompressible Navier-Stokes equations and a standard k-ε turbulence mode to obtain the source of the vibro-acoustics. Second, a one-way-flow structural acoustic coupling method was implemented to study the volute vibrations and behaviors of vibrational noise by adoption. The generation mechanism of vibrational noise of the volute casing was revealed. Third, the parametric analysis method was used to explore the parametric relationship between the Panel Thicknesses (such as front-Panel Thickness [FT], side-Panel Thickness [ST], and back-Panel Thickness [BT]) and the outlet acoustical power of the volute casing surface. The parametric analysis provides a reasonable range of values of three Panel Thicknesses that result in minimal vibrational sound radiation
In Jae Chung - One of the best experts on this subject based on the ideXlab platform.
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Highly Flexible AM-OLED Display With Integrated Gate Driver Using Amorphous Silicon TFT on Ultrathin Metal Foil
Journal of Display Technology, 2010Co-Authors: Sang Hoon Jung, Seung-chan Byun, Nack-bong Choi, Yong-kee Hwang, Soo-young Yoon, In Jae ChungAbstract:This paper introduces the technology behind developing of flexible AM-OLED displays with improved color and reduced bending radius. Developing a-Si TFT fabrication technology using 80-μm ultrathin stainless steel foil as the substrate and integrating driver electronic in the display Panel, we were able to demonstrate a full-color AM-OLED displayed in a curvature of less than 5 cm bending radius. Total Panel Thickness of 0.30 mm, brightness of 100 cd/m2 and color reproducibility of 63% were achieved.
