Back Panel Research Articles

Comparative Study of Indium Oxide Films for High‐Mobility TFTs: ALD, PLD and Solution Process

AbstractDeposition of indium oxide base films for high‐mobility thin film transistors (TFTs) has been an important part in the implementation of high‐resolution and high‐frequency display back panels. In this study, three types of In2O3 (InO) films have been fabricated for TFTs using atomic layer deposition (ALD), pulsed laser deposition (PLD), and solution process, respectively. ALD‐derived InO films show controllable grain formation and optimized TFTs show the field effect mobility of ≈100 cm2 V−1s−1 in both the conventional transistor measurements and critical four‐probe measurements, reaching the level of low‐temperature polycrystalline silicon (LTPS). Combined spectroscopy investigations show that the ALD‐derived InO film features advantages as compared to those of the PLD‐deposited and solution‐processed InO film in providing a smoother surface morphology, good crystallinity, and more orderly atomic growth mode. Moreover, the bias‐stress stability of ALD‐derived TFTs can be improved with further passivation.

Experimental study on electricity generation performance of T‐type direct‐expansion solar PVT heat pump system

AbstractFocusing on the electricity generation performance of a direct expansion solar PVT heat pump system, a novel T‐type optimized collector/evaporator was designed. The experiment used refrigerant R410a as the working medium and was conducted under the average winter ambient temperature of 16°C in Fuzhou. Through experimental comparison, the differences in panel temperature, electricity generation, and efficiency under different radiation intensities were tested against traditional PV panels and honeycomb PVT panels. The experimental results showed that the T‐type PVT system exhibited significant advantages under various weather conditions. The back panel temperature was reduced by 12.74, 8.52, and 13.06°C compared to traditional PV panels and honeycomb PVT panels, respectively, and it maintained a stable increase in electricity generation. The maximum instantaneous electricity output increased by 56.6% relatively, and the total electricity generation increased by 9.3% to 14.5% compared to traditional PV panels. The photoelectric efficiency reached 21.54% and 22.6%, surpassing traditional PV panels and honeycomb PVT panels, with measured values relatively increased by 1.7%, 2.38%, and 2.76%, respectively. Economic evaluation indicated that the T‐type PVT system could save on self‐generated electricity costs, achieving savings of up to 386.50 and 210.81 yuan/year compared to traditional PV panels and honeycomb PVT panels. The T‐type PVT system demonstrated clear advantages in self‐generated electricity costs, significantly reducing costs for application scenarios and providing strong support for the practical application of renewable energy technologies.

Comparative experimental analysis of monocrystalline and polycrystalline photovoltaic panel through hybrid phase change material

Photovoltaics thermal management is utmost necessary as continuous heating of the module decreases the performance. This paper presents a comparative study in terms of performance of two photovoltaic modules namely monocrystalline and polycrystalline using hybrid phase change materials (PCMs). The hybrid PCMs of RT31 and RT 44HC were prepared by method of stirring. The final prepared hybrid PCMs were poured at the back of panel and panel was covered. The purpose of these experiments is to improve the efficiency of polycrystalline and monocrystalline photovoltaic modules and comparing which technology is more efficient having hybrid PCM. The experiments were performed under the room conditions in Taxila, Pakistan. The output parameters of the photovoltaic module appeared to be strongly dependent upon the solar irradiance. The power output and efficiency of monocrystalline and polycrystalline photovoltaic module were measured. The monocrystalline panel maximum temperature was 36.59 °C as compared to polycrystalline panel which was 40.23 °C. As the radiation intensity increased till noon, electrical power was improved, and it was 6.52 W in monocrystalline panel as compared to polycrystalline panel which was 6.32 W. Electrical conversion efficiency was also observed, and it was maximum up to 11.84 % in monocrystalline panel. The higher performance was observed in case of monocrystalline panel having hybrid in terms of performance as compared to polycrystalline panel.

Experimental investigation of the cooling effect of topology-optimized structure on photovoltaic wall

Nowadays, photovoltaic walls have been widely used, which will generate heat behind the PV panel and cause overheating, making the lower efficiency of the PV panel and higher temperature of the exterior wall. Topology optimization structures have been explored in many fields for heat dissipation, but few are applied in heat dissipation of the PV wall systems. The purpose of this paper is to experimentally investigate the effect of topological optimized structure of the copper sheet on electricity generation efficiency of the PV panel and cooling effect of the exterior wall. The topology optimization method is used to numerically find the optimal geometric configuration of high thermal conductivity material of copper sheet on the back of the photovoltaic panel. And the topology-optimized copper sheet is fabricated by 3D printing and experimented with four different cases. The experimental results show that under natural convection, compared with the reference photovoltaic wall, the largest reduction of temperature of the photovoltaic panel (ΔTpv) and the largest output power increment rate (ΔE/E) of the photovoltaic wall with topology-optimized copper in the 5 test days are 2.7℃and 1.30 % respectively, and the largest reduction of temperature of the exterior wall (ΔTw) is 1.6℃. Under forced convection, the temperature reduction (ΔTpv) and the increment of output power (ΔE) of the photovoltaic panel and the temperature reduction of the exterior wall (ΔTw) increase significantly under wind speed of 1 m/s compared with natural convection. But when the wind speed is increased from 1.5 m/s to 2 m/s, the increment is less obvious. Therefore, the optimal wind speed in the air gap of the photovoltaic wall with topology-optimized copper is 1 ∼ 1.5 m/s. At last, based on the results of our previous study, the optimal-constructed photovoltaic wall in hot summer and cold winter area is discussed. The results of this research can provide some technical guidance for engineering application of the photovoltaic panel integrated with walls in similar climate regions.

The Effect of Radiation Intensity on the Performance of Direct-Expansion Solar PVT Heat Pump Systems

The objective of this study was to investigate the impact of solar radiation intensity on the performance of direct-expansion solar PVT heat pump systems. To this end, an experimental setup was constructed for direct-expansion photovoltaic (PVT) solar heat pump water heating systems and photovoltaic (PV) power generation systems. The system performance and main parameters were analyzed and discussed under different solar radiation intensities. The winter experiments in southern China revealed that the exhaust temperature of the heat pump unit varied considerably under clear conditions, while the back temperature remained stable, fluctuating between approximately −13.5 °C and 24 °C. In contrast, the power generation of PVT panels increased with the increase in radiation intensity, from 78.33 W to 122.68 W, for an increase of 56.6%. Furthermore, the total electricity generation of the PVT panels was higher than that of PV panels, with an increase of 8.7–8.3%. Nevertheless, discrepancies between experimental and theoretical data were observed, particularly under overcast conditions, where the back panel temperature error was pronounced. Additionally, the system exhibited enhanced stability at elevated temperatures in comparable environments, accompanied by an improvement in the system’s coefficient of performance (COP) by 5.67%.

Cross-cultural adaptation and psychometric validation of <i>The Continuous Traumatic Stress Response Scale</i>: Ukrainian version

Adapting and validating diagnostic tools aimed to evaluate the post-traumatic effects of war in low-income countries is essential for assessing needs and planning support programs. This paper will describe the process of cross-cultural adaptation and psychometric validation of the Continuous Traumatic Stress Response (CTSR) Scale for war-affected Ukraine. The study includes Phase 1, Translation and cross-cultural adaptation of the Scale, and Phase 2, Psychometric validation of the Scale. Cross-cultural adaptation goes through four stages: forward translation, expert panel review and back translation (n=3), pretesting and cognitive interviewing mental health professionals (n=8), and final version. Psychometric validation includes exploratory (n=200) and confirmatory (n=219) factor analyses, internal consistency, construct validity and test-retest reliability. Findings from the current research indicate that the components identified through factor analyses differed from those in the original questionnaire. While all original items in the questionnaire were retained, they merged into two new factors: “Exhaustion and Rage” and “Fear and Betrayal”. The results show that the overall Cronbach’s Alpha is .858, indicating a high level of internal consistency. Significant correlations exist between the total CTSR Scale score, the subscale scores, PTSD (PCL-5), moral injury (MISS-C-SF), depression (PHQ-9), and anxiety (GAD-7) symptoms, indicating construct validity. The findings demonstrate the test-retest reliability of the CTSR Scale and have practical implications for how it could be implemented in trauma-informed care. Disclosure Statement The authors reported no potential conflicts of interest. * Corresponding author: Larysa Zasiekina, 0000-0001-8456-0774zasyekina.larisa@vnu.edu.ua

Investigating Performance of Hybrid Photovoltaic–Thermal Collector for Electricity and Hot Water Production in Nigeria

The research work explores the impact of temperature on Silicon photovoltaic (PV) panels, considering Nigeria as a case study. It is found that high solar radiation in Nigeria increases the surface temperature of PV panels above 25 °C of the optimal operating temperature. The redundant energy gain from solar irradiance creates heat at the rear of solar panels and reduces their efficiency. Cooling mechanisms are therefore needed to increase efficiency. In this study, we demonstrated a unique hybrid system design employing a heat exchanger at the back of the panel, with water circulated through the back of the PV panel to cool the system. The system was simulated using TRNSYS at three locations in Nigeria—Maiduguri, Makurdi, and Port Harcourt. The results of the peak annual electrical power output in Maiduguri give a power yield of 1907 kWh/kWp, which is the highest, due to a high solar radiation average of 727 W/m2 across the year. For Makurdi, the peak annual electrical power output is 1542 kWh/kWp, while for Port Harcourt the peak power output is 1355 kWh/kWp. It was observed that the surface temperature of Polycrystalline Si-PV was decreased from 49.25 °C to 38.38 °C. The electrical power was increased from 1526.83 W to 1566.82 W in a day, and efficiency increased from 13.99% to 15.01%.

Dynamic response of GFRP/Nomex honeycomb sandwich panels subjected to multiple hail impacts – An experimental study

AbstractNowadays, more and more aircraft components are made of composite sandwich structures, and ice impacts are prone to cause internal damage to composite sandwich structures, so it is crucial to study the impact of hail on composite sandwich structures. Since hail impacts may occur several times at a single point, an experimental approach was used to investigate the dynamic response of GFRP/Nomex honeycomb sandwich panels under multiple hail impacts. The dynamic response of the structure was investigated in terms of response rate and deflection‐profile curves using 3D digital image correlation methods, and the effects of impact energy, hail size, and number of impacts on the impact resistance of the honeycomb sandwich structure were explored. The results show that the dynamic response process of sandwich panels can be categorized into the ball‐and‐crown phase, the rebound phase, and the vibration phase. Under the same impact energy, the impact of small‐sized hailstones is more threatening to honeycomb sandwich panels. As the number of impacts increases, the maximum deflection value of the back panel first increases uniformly, and when the layered damage area reaches the threshold value, fiber stripping occurs, and the increment of the maximum deflection value increases significantly.Highlights Since hail impacts may occur several times in real situations, this study conducted multiple impact experiments for one impact site. The dynamic response and damage pattern of the GFRP/Nomex honeycomb sandwich panels under multiple hail impacts were also investigated. The dynamic response process of GFRP/Nomex honeycomb sandwich panels was categorized into three phases: ball‐crown stage, rebound stage, and vibration stage. With the increase of the number of impacts, fiber stripping and fiber break damage began to occur when the layered damage area of the panel reached the threshold value. The honeycomb core has three main failure modes: cell wall folds, cell wall fracture, and cell wall debonding at the TGPW interface. Small‐diameter hails pose a more significant threat of damage to honeycomb sandwich panels at the same impact energy.

Development of partitioned rectangular-shaped heat sink for photovoltaic thermal systems and performance evaluation using TiO2/Water-based nanofluids

The current study presents a partitioned rectangular-shaped heat sink for improving the PVT system performance. The experiment was examined under various experimental parameters. Five cooler block types with different dimensions were arranged to share the same total contact area with the panel back surface. These cooler blocks were placed in different arrangements, namely (PVT-I, PVT-II, PVT-III, PVT-IV, PVT-V), and studied comparatively using water. The dimensions and numbers of each cooler block arrangement were altered, while maintaining the same surface area in contact with the photovoltaic panel. Through the response surface methodology (RSM) optimization, the optimal arrangement with the best performance was determined, and then TiO2/nanofluid was applied to that arrangement with different volumetric concentrations. Using water, the highest electrical and thermal efficiencies were obtained by case PVT-III with values of 19.39 % and 63.72 %, respectively. This was followed by PVT-II, PVT-V, PVT-I, and PVT-IV in that order for electrical efficiency; and at the same time by PVT-II, PVT-I, PVT-IV, and PVT-V in that order for thermal efficiency. The RSM method recommended the optimal arrangement case as case PVT-III. By using nanofluid in that case arrangement, the highest electrical efficiency value was recorded upon using 0.3 wt% and operating the system at 1.5 L/m and 900 W/m2. Regarding the thermal efficiency results, in that case, the highest and lowest values were recorded upon using 0.3 wt% and 0.1 wt%, respectively, with values of 72.49 % and 31.19 %. Increasing the volumetric concentrations positively reflected on the system's performance, resulting in high efficiencies being achieved. In addition, the highest electrical efficiencies were obtained at high levels of solar irradiance and flow rates.

Deformation and failure of asymmetric sandwich structures under low-velocity impact

This work aims to analyze the dynamic response of asymmetry sandwich structure to low-velocity impact and study the influence of different panel thickness on sandwich structure impact performance. The failure mechanism is analyzed by combining experiment, theoretical analysis and simulation. The finite element model (FE model) was constructed in the software ABAQUS, and established a theoretical model to predicting the damage mode. Moreover, the optimal design of the asymmetric sandwich structure is studied by analyzed the EA and SEA of the structure. Pendulum impact test was carried out, the FE model was verified by experiment, and the theoretical model was verified by experiment and simulation. The results show that the front panel mainly affects the energy absorption capacity, and the back panel mainly affects the failure load. When both the front panel and the back panel are less than 1 mm, the structure shows panel fracture failure mode. When the front panel is less than 1 mm while the back panel is greater than 1 mm, intention failure mode occurs. When the front panel is greater than 1 mm, all failure modes of the structure are core shear failure. After research, when the thickness of the front panel is 2 mm and the thickness of the back panel is 3 mm, the EA and SEA are higher, and the structure is more economical.

Design and optimization of battery and thermal management system for AC photovoltaic energy module

The utilization of renewable energy sources has increased due to concerns about climate change. However, injecting the power from renewable energy sources into grid-tied systems is challenging. The techno-economic analysis a photovoltaic (PV) energy systems is investigated. As a result, this paper presents AC-PV module for Grid-Tied and Off-Grid Scenarios via optimization, modeling, and test results. Even though the output of a PV panel is DC voltage, a three-port inverter and a lithium-ion battery pack are integrated with the back of the PV panel. They are packaged as a PV system module that makes the module output have AC voltage. Therefore, an optimized AC-PV module can be a solution for residential and commercial use, which are grid-tied systems; it can be very efficient for those without access to electricity, which is an off-grid system. An integrated battery and thermal management strategy is crucial for this AC-PV module. In the article, the battery capacity optimization, the electrical and the thermal model of the battery pack, battery heat generation model are discussed by using stochastic analysis techniques; the battery test results are also obtained to identify the models’ parameters and a control algorithm is proposed to extract the battery information such as temperature, current, voltage, SoC and SoH of the battery pack.

Improvement of the sound absorption performance of sandwich panel using inhomogeneous micro-perforations

Sandwich structures are widely used in several fields because of their mechanical performance with low weight. In this paper, a sandwich panel made of a core and a top and a back panel is investigated using the finite element method. The core consists of 33 hexagonal cells and each cell is connected to a micro-perforation. To improve the sound absorption, inhomogeneous micro-perforations are considered within the top panel. It is shown that with homogenous micro-perforations made of the same diameter, the sound absorption coefficient presents only one resonant peak. When 2, 3, and 6 different sets of micro-perforation diameters are considered, the sound absorption coefficient presents, respectively, 2, 3, and 6 resonance peaks where the surface impedance is close to that of the air. When each micro-perforation diameter is different resulting in inhomogeneous distribution of micro-perforations within the top panel, the sound absorption frequency band is widened and the absorption coefficient value increases while without micro-perforations the absorption coefficient of the sandwich panel is zero over the entire frequency range. The studied structure can offer high mechanical stiffness and good sound absorption performance.

Comparative study on the dynamic response of an out-of-plane gradient bionic sandwich circular plate under two types of impact loading

Out-of-face gradient sandwich structures have been widely studied for their excellent impact resistance. One uniform and two out-of-plane gradient cores are proposed based on the bionic structure of Royal Water Lily, and the midspan deflection of the back panel and the energy absorption of the out-of-plane gradient sandwich structures under various blast loads are studied. Two frequently adopted methods of explosive loading are applied to the sandwich panels, and the responses are contrasted for the loads applied as a time-dependent pressure history versus imposition of the initial velocity. The effect of the fluid–structure interaction is considered in the blast impulsion, and the dynamic responses of the sandwich structures with different out-of-plane density arrangements are analyzed under two loading approaches. Results show that the energy absorption of the core layer under the prescribed velocity approach is approximately 3–5 times that of the applied pressure approach, while the back panel deflections of different out-of-plane gradient sandwiches are similar. There are significant differences in the deformation mechanisms of structures under these two types of impact loads. Under the same type of impact load, the core compression process of the out-of-plane positive gradient sandwich panel is decoupled from the whole tensile bending deformation process of the structure, whereas the core compression process of the out-of-plane negative gradient sandwich panel is strongly coupled with the whole tensile bending deformation process of the structure. The related research will lay the foundation for an in-depth understanding of the theoretical study of the impact of out-of-face gradient sandwich structures.

An experimental analysis of a hybrid photovoltaic thermal system through parallel water pipe integration

The global research community has increasingly focused on sustainable energy solutions to combat the environmental challenges posed by extensive fossil fuel consumption. This paper presents a new simple approach to enhance the electric efficiency of photovoltaic (PV) panels through efficient cooling techniques using simple parallel water pipes on the back of the PV panel. Additionally, the waste heat generated during this process is harnessed as a valuable heat source for residential hot water systems. Experimental measurements were conducted on both the reference PV panels without cooling and the PV/T system equipped with cooling pipes. A comprehensive energy analysis was performed to compare their performance. The results demonstrate that the cooled PV/T system exhibits consistently higher electric efficiency due to effective cooling by about 10%, resulting in surface temperature reduction and enhanced performance. The system also demonstrates a significant improvement in waste heat recovery, making it a practical and promising choice for sustainable energy applications.

The Behavior of Glass Fiber Composites under Low Velocity Impacts.

This paper presents experimental results on the behavior of a class of glass fiber composites under low velocity impacts, in order to analyze their usage in designing low velocity impact-resistant components in car and marine industries. Also, a finite element model at the meso level (considering yarn as a compact, homogenous and isotropic material) was run with the help of Ansys Explicit Dynamics in order to point out the stages of the failure and the equivalent stress distribution on the main yarns in different layers of the composite. The composites were manufactured at laboratory scale via the laying-up and pressing method, using a quadriaxial glass fiber fabric (0°/+45°/90°/-45°) supplied by Castro Composites (Pontevedra, Spain) and an epoxy resin. The resin was a two-component resin (Biresin® CR82 and hardener CH80-2) supplied by Sika Group (Bludenz, Austria). The mass ratio for the fabric and panel was kept in the range of 0.70-0.77. The variables for this research were as follows: the number of layers of glass fiber fabric, the impact velocity (2-4 m/s, corresponding to an impact energy of 11-45 J, respectively) and the diameter of the hemispherical impactor (Φ10 mm and Φ20 mm) made of hardened steel. The tests were performed on an Instron CEAST 9340 test machine, and at least three tests with close results are presented. We investigated the influence of the test parameters on the maximum force (Fmax) measured during impact, the time to Fmax and the duration of impact, tf, all considered when the force is falling to zero again. Scanning electron microscopy and photography were used for discussing the failure processes at the fiber (micro) and panel (macro) level. At a velocity impact of 2 m/s (corresponding to an impact energy of 11 J), even the thinner panels (with two layers of quadriaxial glass fiber fabric, 1.64 mm thickness and a surface density of 3.51 kg/m2) had only partial penetration (damages on the panel face, without damage on panel back), but at a velocity impact of 4 m/s (corresponding to an impact energy of 45 J), only composite panels with six layers of quadriaxial fabric (5.25 mm thickness and a surface density of 9.89 kg/m2) presented back faces with only micro-exfoliated spots of the matrix for tests with both impactors. These results encourage the continuation of research on actual components for car and naval industries subjected to low velocity impacts.

Formability classifier for a TV back panel part with machine learning

Formability classifier for a TV back panel part with machine learning

Dew-point evaporative cooling of PV panels for improved performance

Solar energy is an important energy source for a sustainable future. The advancements of solar cells for electricity production require improvements in the cooling technology. Conventional air cooling is not able to cool the photovoltaic (PV) panels effectively. On the other hand, dew-point evaporative cooling (DPEC) can bring down the inlet air temperature below its wet bulb which makes itself an excellent candidate for PV cooling. In this work, a novel cooling configuration that consists of two wet channels: one in the cooler (conventional DPEC) to produce the pre-cooled supply air and the other at the back of the PV panel, was proposed. A physics-based mathematical model utilizing local weather conditions was developed for the system to investigate its transient performance. The cooling performance and subsequent improvement in the PV’s energy efficiency of the proposed system were compared with a traditional DPEC-based cooling approach. It was observed that the proposed system can maintain an efficiency of more than 15% (with 16.7% maximum) under two environmental conditions in summer, which is an increase of 16.4% compared to air cooling. The proposed PV cooling method will help to improve the overall performance of the solar PV systems and increase renewable energy utilizations.

Investigation on the thermal insulation and evaporative resistance of outdoor backpacks based on a sweating thermal manikin

The thermal insulation and evaporative resistance of backpacks are vital for users’ physical performance and safety. In hot humid weather, users carrying a backpack with high thermal insulation and evaporative resistance may face the risk of heat stress, such as heat stroke. However, few studies have investigated the thermal insulation and evaporative resistance of backpacks. In this study, a sweating thermal manikin was employed to evaluate the thermal insulation and evaporative resistance of backpacks. Four backpack samples with different back panel designs were tested under two load conditions (0 and 5 kg), two wind speeds (0.3 and 1.5 m/s), and two body movement levels (inactive 0 km/h and walking at a 2.5 km/h speed). Test results showed that the back panel designs fundamentally determined the thermal insulation and evaporative resistance. Both the air-permeable design of the back panel’s filling material and the ventilation design of the back panel structure could improve the heat dissipation performance of the backpack. However, the ventilation designs that formed tunnels with openings between the backpacks and the human body showed more efficient heat dissipation. In practical application, the resultant thermal insulation and evaporative resistance were affected by the load condition, wind speed, and body movement. However, backpacks with better ventilation were less affected by external conditions. The findings of this study provide fundamental knowledge to improve the heat dissipation property of outdoor backpacks.

Experimental study of the performance of open–type refrigerated display cabinet

<p>This paper presents experimental investigations of the efficiency of an open-type refrigerated display cabinet used to store food at temperatures between –1 and +7 °C. The purpose of the study was to increase the efficiency of the open-type cabinet by improving its design. The cabinet has five shelves for food products with lengths of 350-600 mm. The spacing between the base and the first shelf is 280 mm, and between the other shelves it is 250 mm. The air enters the cabinet from the return air grille (RAG) at the bottom of the front panel, fans blow air through the evaporator, and the cooled air travels through a tunnel to the top of the refrigerator. The perforated distributor at the top distributes the cooled air, and part of the air is blown through the perforated back panel and the other part passes through the air-off honeycomb (dimensions (WH) are 12020 mm) at the front top of the cabinet, thus forming an air curtain between the inside of the refrigerator and the ambient warm air to protect the chilled food products. The cooled air entering through the perforated back panel into the display area helps maintain the required food temperature. In this study, two versions of the refrigerated cabinet were analyzed. The first version is the standard refrigeration cabinet and the second version is the same cabinet but with a change in the angle of inclination of the honeycomb and a reduction in the depth of the shelves. Air and test product temperatures were measured with thermocouples, and electrical energy consumption was measured with the Carel MT300W1100 energy meter. The experimental results show that the infiltration ratio decreases from 38.7 to 27.7%, and the 24-hour electrical consumption decreases from 24.91 to 19.22 kWh in the case of the modified cabinet. The average air temperature in the return air grille (RAG) decreased from 7.5 to 6.52 °C with the same temperature settings. The average temperature of the M packages decreased by 0.2-2.2 °C depending on the position in the refrigerator.</p>

Investigations on predictions of cooling capacity for open refrigerated display cabinet using CFD approach with different positions of perforated back panels

Investigations on predictions of cooling capacity for open refrigerated display cabinet using CFD approach with different positions of perforated back panels