The operating temperature of photovoltaic panels represents an important parameter that influences their conversion efficiency. High operating temperatures determine a decrease of maximum output ...power in the same conditions of solar radiation. The study presents a numerical approach of the reduction of temperature of the photovoltaic panels by using the air cooled heat sinks. The heat sink is conceived as a ribbed wall, realized of a high thermal conductivity material. The cooling efficiency is studied for different configurations of the heat sink, obtained by modifying the angle between the ribs and the base plate. The numerical model was realized using ANSYS-Fluent software for turbulent flow and the results are presented for the average temperature of the photovoltaic panel.
The aim of the study is to simulate the functionality of a HVAC system in different situations, summer and winter time, using specialized software ANSYS-Fluent. A 2D building model was realized and ...simulating the internal conditions represented the main elements of the study.
There are studied the indoor air temperature and air velocity in different conditions. The results are presented as graphs/plots and spectra of interest parameters. HVAC system functionality simulation using ANSYS-Fluent is providing important results for the studied scenario.
At the end of 2019, a variation of a coronavirus, named SARS-CoV-2, has been identified as being responsible for a respiratory illness disease (COVID-19). Since ventilation is an important factor ...that influences airborne transmission, we proposed to study the impact of heating, ventilation and air-conditioning (HVAC) with a variable air volume (VAV) primary air system, on the dispersion of infectious aerosols, in a cardiac intensive care unit, using a transient simulation with computational fluid dynamics (CFD), based on the finite element method (FEM). We analyzed three scenarios that followed the dispersion of pathogen carrying expiratory droplets particles from coughing, from patients possibly infected with COVID-19, depending on the location of the patients in the intensive care unit. Our study provides the mechanism for spread of infectious aerosols, and possibly of COVID-19 infection, by air conditioning systems and also highlights important recommendations for disease control and optimization of ventilation in intensive care units, by increasing the use of outdoor air and the rate of air change, decreasing the recirculation of air and using high-efficiency particulate air (HEPA) filters. The CFD-FEM simulation approach that was applied in our study could also be extended to other targets, such as public transport, theaters, philharmonics and amphitheaters from educational units.
Based on the review of the original descriptions of Pachymerium antipai Cpue, 1968, P. atticum Verhoeff, 1901 and P. tabacarui Cpue, 1968 from Romania and the direct study of the external anatomy of ...P. ferrugineum (C. L. Koch, 1835) and Geophilus flavus (De Geer, 1778) from Romania, Egypt, Italy and Russia, P. antipai and P. aticum sensu Cpue (1968) are proposed as junior subjective synonyms of P. ferrugineum, while P. tabacarui is proposed as a junior subjective synonym of G. flavus. The presence of P. atticum in Romania is hereby considered doubtful. Revisions to the diagnosis of Pachymerium are proposed to help differentiate it from other geophilid genera. A discussion of the relative suitability of different morphological characters for distinguishing species within Pachymerium is also included.
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.
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.
Globally, there are several critical infrastructure networks (water and gas networks) whose disruption or destruction would significantly affect the maintenance of vital societal functions, such as ...the health, safety, security, and social or economic well-being of people. They would also have significant local, regional, and national impacts as a result of the inability to maintain those functions, and would have similar cross-border effects. The main objective of this article is to investigate by comparative numerical studies the structural response of three types of buried pipes made of different materials, primarily steel, concrete, and high-density polyethylene, resulting from the impact of the environment through exceptional external actions, such as explosions at the surface of the land in the vicinity of the laying areas. The dynamic transient analysis of the equation of motion with the application of the explicit integration procedure was performed with the ANSYS numerical simulation program. This study allows designers to solve complex problems related to the quality of the laying ground of water networks to canals. The knowledge accumulated gives us the possibility to correctly specify the optimal economic and technical value of the ratio between the laying depth of pipes and their diameter, the importance of the radius ratio of the pipe and the thickness of its wall, and, importantly, the improvement of the quality of the foundation ground. Following the results obtained, it is estimated that the optimal economic and technical value of the ratio between the laying depth of the pipes (H) and their diameter (D) is 3, regardless of the material from which the pipe is made.
The typical CT features of COVID-19 pneumonia include multifocal and bilateral ground-glass opacities with or without consolidation, found in both lungs, predominantly at peripheral, and posterior ...regions, bronchovascular thickening, crazy pavement appearance (ground-glass opacities with superimposed interlobular septal thickening). Atypical imagistic findings such as lung cavitation were rarely reported. In this report we describe the case of a 42 years old, healthy man with severe COVID-19 pneumonia who developed two pulmonary cavities during recovery. The pulmonary cavitations formed in the aria of the lung where patchy air space opacification was seen in early stages. There were no signs of invasive fungal or bacterial infection and the complementary investigations have ruled out other possible etiology for lung cavitation. Although the pathophysiological mechanism involved in the origin of the pulmonary cavities is not fully known, it could be closely related to diffuse alveolar damage in severe COVID-19 pneumonia.
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%.
COVID-19 is currently a major health problem, leading to respiratory, cardiovascular and neurological complications, with additional morbidity and mortality. Spinal infections are rare, representing ...around 1% of all bone infections and comprising less than 2 per 10,000 of all hospitalizations in tertiary care centers. Spondylodiscitis is a complex disease, with challenging diagnosis and management. We report the case of a 45-year-old man, non-smoker hospitalized for severe COVID-19 disease with respiratory failure. Post-COVID-19, in the 8th week after discharge, he was diagnosed by magnetic resonance imaging with spondylodiscitis, but etiology was not confirmed by microbiological investigations. Antibiotics were used, considering the identification of MRSA from cultures of pleural fluid and nasal swab, but surgical intervention was not provided. Clinic, biologic and imagistic were improved, but rehabilitation and long term follow up are necessary. We concluded that spondylodiscitis with spinal abscess is a rare but severe complication post-COVID-19 disease, due to dysbalanced immune response related to the respiratory viral infection, endothelial lesions, hypercoagulation and bacterial superinfection.
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