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The integration of phase change materials (PCMs) into building structures has become a focal point for researchers aiming to enhance thermal comfort and energy efficiency in buildings. This comprehensive article delves into the analysis of PCMs embedded in room walls, emphasizing their role in thermal regulation and the innovative application of computational fluid dynamics (CFD) in evaluating their performance. [ABSTRACT FROM AUTHOR]

This study investigates the airborne transmission risk of infectious diseases in a classroom setting, aiming to develop a comprehensive risk measurement model. The research employs a combination of computational fluid dynamics simulations, viral load measurements, and epidemiological data to analyze airflow patterns, ventilation efficiency, and viral dispersion in classrooms. Real-time monitoring of air quality, temperature, and humidity is integrated to establish a risk assessment framework. The findings reveal the significance of proper ventilation and strategic classroom layout in mitigating airborne disease transmission. This research offers practical insights for educational institutions to implement informed strategies to minimize airborne risks, ensuring a safer learning environment. [ABSTRACT FROM AUTHOR]

In this research, we investigate the thermal behavior of storage tanks subjected to varying environmental conditions. Through numerical simulations and experimental analysis, we assess heat transfer mechanisms, temperature distribution, and energy consumption patterns of both insulated and non-insulated tanks. Our study aims to optimize tank design and insulation materials to minimize heat losses, improve energy efficiency, and enhance the safety and longevity of storage tanks. Findings reveal that incorporating optimal insulation materials and techniques can significantly reduce energy consumption and maintain the desired temperature range within the tank, thus providing valuable insights for future storage tank design and management. [ABSTRACT FROM AUTHOR]

This research article presents a computational fluid dynamics (CFD) analysis of the heat transfer enhancement in a radiator using nanofluid. The study investigates the effect of varying the concentration of nanoparticles and the inlet velocity of the fluid on the heat transfer rate and pressure drop. The simulation results show that the use of nanofluids in radiators leads to a significant increase in heat transfer rate compared to traditional fluids. However, the pressure drop also increases with the concentration of nanoparticles, which can affect the overall efficiency of the radiator. The study provides valuable insights into the design and optimization of nanofluid-based radiators using CFD simulations. [ABSTRACT FROM AUTHOR]

The paper presents the analysis of the building integrated photovoltaic panels (BIPV) realized for the same photovoltaic system, placed in different locations, for the continental climate of Romania. For all studied cases, the photovoltaic (PV) system is examined in various vertical configurations, considering the integration into buildings placed in urban agglomerations, characterized by small horizontal surfaces, but generous facades. For the analyzed situations it is assumed that the PV panels are fixed in vertical position. Therefore, one of the possibilities of raising their efficiency consists in controlling the operating temperature of the photovoltaic cells. The operating parameters of the photovoltaic panels are studied in case of integration at 10 m height above the ground and the results are reported on the unit surface. The model and the functioning parameters are processed using TRNSYS software. The results are analyzed for average daily, monthly and yearly values. The results reveal some major differences obtained for the same system placed in different locations or orientations. The average efficiencies for maximum production months are lower than annual ones, while the daily values for efficiency are lowest. These values are directly dependent on the intensity of solar radiation and are negatively influenced by the operating temperature of the photovoltaic panel.

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

The numerical modeling of the effect of wind direction and velocity over the air cooling of PV panels with heat sinks is realized. During the study, a random PV panel with typical characteristics was analyzed for three different wind directions—towards its back, towards its front and from the side. The analysis was realized on a fixed PV panel, oriented to the south, with an inclination of 45 degrees from the horizontal position. The accuracy of the numerical simulation was achieved by comparison with the experimental studies presented in the literature and by comparing the NOCT conditions. The numerical study is focused on different types of heat sinks attached to a typical PV panel. The fins were distributed both horizontally and vertically. A challenging task consisted in simulation of the real wind conditions around the PV panel by taking into account the entire air domain. The simulations were realized for air velocity vair from 1 m/s to 5 m/s, solar radiation of G = 1000 W/m2 and ambient temperature tair = 35 °C. The output parameters analyzed were the average temperature of PV panels and their power production. Although the lowest temperatures were achieved for the back wind, the cooling effect was more intense for the side wind. The other direction studied also determined the cooling of PV panels. The passive cooling solutions analyzed introduced a rise of maximum power production between 1.85% and 7.71% above the base case, depending on the wind direction and velocity. [ABSTRACT FROM AUTHOR]

After installing a solar panel system, the orientation problem arises because of the sun's position variation relative to a collection point throughout the day. It is, therefore, necessary to change the position of the photovoltaic panels to follow the sun and capture the maximum incident beam. This work describes our methodology for the simulation and the design of a solar tracker system using the advantages that the orientation and efficiency of the PV panel offer due to the latitude and the number of hours of sunshine in the testing area. This proposed methodology is experimentally validated through the implementation of a single-axis solar tracker at a specific location (36.261° latitude), which allowed the incorporation of a high-availability tracking mechanism, low precision, and low cost. Based on the results, the feasibility of this type of solar tracker for latitudes close to 36° was demonstrated, as this tracking system costs less than traditional commercial systems. Furthermore, this system increased the collection efficiency compared to a fixed device. Our results provide an excellent platform for engineering technology researchers and students to study the design theory of a sun-tracking solar system. [ABSTRACT FROM AUTHOR]

In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results of an experimental campaign performed on a full-scale double-skin façade using the in-situ measurement methodology. The thermodynamic behavior of the façade is studied under real exterior climatic conditions in Romania in hot and cold seasons, and performance indicators in terms of pre-heating efficiency and dynamic insulation efficiency were determined. Three summer periods are analyzed corresponding to the outdoor air curtain scenario for three ventilation modes in naturally or mechanically ventilated single-story DSF. Results revealed that the third ventilation scenario, which combines horizontal and vertical openings, gives the best efficiency of 71.3% in the double skin façade functioning. During the cold season, the channel façade behaved like a thermal buffer between the building and the exterior air, ensuring the thermal energy for partial or integral heating of the building. [ABSTRACT FROM AUTHOR]

This paper presents a numerical model regarding the passive cooling of PV panels through perforated and non-perforated heat sinks. A typical PV panel was studied in a fixed position, tilted at 45 degrees from the horizontal with the wind direction towards its backside. A challenging approach was used in order to calibrate the base case of the numerical model according to the NOCT conditions. Further validation of the accuracy of the numerical simulation consisted of a comparison between the results obtained for the base case, or heat sink, with horizontal non-perforated fins and the experiments presented in the literature. Six types of heat sink attached to the backside of the PV panel were numerically studied. The analyzed configurations focused on heat sinks with both perforated and non-perforated fins that were distributed horizontally and vertically. The CFD simulation was also conducted by modeling the air volume around the PV panel in real wind conditions. The main output parameters were the average temperature and the convective heat transfer coefficient on the front and back of the PV panel. The most important effect of cooling was achieved in low wind conditions and high levels of solar radiation. For vair = 1 m/s, G = 1000 W/m2 and ambient temperature tair = 35 °C, the percentage of maximum power production achieved 83.33% for the base case, while in the best cooling scenario it reached 88.74%, assuring a rise in the power production of 6.49%. [ABSTRACT FROM AUTHOR]

Background: The aim of our study was to identify an optimal heating system for the analyzed church. We also evaluated the energy consumption of the existing system and of those proposed in order to choose the best heating system. Methods: We analyzed the current existing heating system, a mixed system (static heaters and hot air heating) in a Romanian heritage church, build in the 16th century, and we compared it with an underfloor heating system that has been mentioned in the literature as an alternative for church heating. We used a computational fluid dynamics (CFD) analysis of the indoor climate with two turbulence models (k-ε and k-ω). Results: Comparing the two heating systems through boxplot graphs, we could highlight pertinent conclusions regarding the temperatures and velocities of the measured air currents. Thus, of all the heating systems, the underfloor heating had the lowest temperatures, but the highest air velocities, in the churchgoers area, especially under the towers zone. Conclusions: We observed that the underfloor heating system was more efficient than the existing heating system (static heaters and hot air heating), ensuring heritage conservation and high thermal comfort to the churchgoers. [ABSTRACT FROM AUTHOR]