Future assessment of the impact of the COVID-19 pandemic on the electricity market based on a stochastic socioeconomic model.

This paper proposes a time-series stochastic socioeconomic model for analyzing the impact of the pandemic on the regulated distribution electricity market. The proposed methodology combines the optimized tariff model (socioeconomic market model) and the random walk concept (risk assessment technique) to ensure robustness/accuracy. The model enables both a past and future analysis of the impact of the pandemic, which is essential to prepare regulatory agencies beforehand and allow enough time for the development of efficient public policies. By applying it to six Brazilian concession areas, results demonstrate that consumers have been/will be heavily affected in general, mainly due to the high electricity tariffs that took place with the pandemic, overcoming the natural trend of the market. In contrast, the model demonstrates that the pandemic did not/will not significantly harm power distribution companies in general, mainly due to the loan granted by the regulator agency, named COVID-account. Socioeconomic welfare losses averaging 500 (MR$/month) are estimated for the equivalent concession area, i.e., the sum of the six analyzed concession areas. Furthermore, this paper proposes a stochastic optimization problem to mitigate the impact of the pandemic on the electricity market over time, considering the interests of consumers, power distribution companies, and the government. Results demonstrate that it is successful as the tariffs provided by the algorithm compensate for the reduction in demand while increasing the socioeconomic welfare of the market.

Climatization systems for Brazilian dental teaching clinics: a narrative review in the context of the COVID-19 pandemic / Sistemas de climatização das clínicas de ensino odontológico brasileiras: uma revisão narrativa no contexto da pandemia da COVID-19

COVID-19 outbreackhas reaffirmed the need to maintain ventilation of dental environments properly. This study was carried out to encourage a reflective analysis of the risks of air contamination in Brazilian dental clinics. A narrative review of the literature was carried out on the recommendations of heating, ventilation and air conditioning (HVAC) systems in dental environments, considering the risks of air contamination in Brazilian dental teaching clinics. The literature research was conductedin the PubMedand Google Scholar databases and the main studiesthat evaluated the climatization systems and portable high efficiency particulate air filtration (HEPA)units in dental environments were included. Furthermore, it were analyzed the guidelines of the Centers for Disease Control and Prevention, the Brazilian National Health Surveillance Agency, the Brazilian Ministry of Health and important institutions of the different countries. After the initial research, a review of the guidelines and articles that assess the use of HEPA units to improve air cleanliness. This analysis was done by different groups of researchers. All documents mentioned that the air quality of the dental offices must follow the protocols in current legislation to ensure the safety of the environs. Theyreaffirmed that the COVID-19 pandemic makes it imperative that dental environments equipped with air conditioning have mechanical air renewal devices. An alternative for Brazilian dental teaching clinics equipped with mini-splits or window air conditioning could be the installation of exhaust fans and portable HEPA filter units to exchange air and reduce aerosols inside the environments (AU).

O surto de COVID-19 reafirmou a necessidade de manter adequadamente a ventilação dos ambientes odontológicos. Este estudo foi realizado para incentivar uma análise reflexiva sobre os riscos de contaminação do ar em clínicas de odontologia. Foi realizada uma revisão narrativa da literatura sobre as recomendações dos sistemas de aquecimento,ventilação e ar-condicionado (AVAC) em ambientes odontológicos, considerando os riscos de contaminação do ar nas clínicas de ensino odontológico brasileiras. A pesquisa bibliográfica foi realizada nas bases de dados PubMed e Google Acadêmico e foram incluídos os principais estudos que avaliaram os sistemas de climatização e unidades portáteis com filtragem de partículas de alta eficiência(HEPA)em ambientes odontológicos. Além disso, foram analisadas as diretrizes do Centro de Controle e Prevenção de Doenças, da Agência Nacional de Vigilância Sanitária, do Ministério da Saúde e de importantes instituições de diferentes países. Após a pesquisa inicial, foi realizada uma revisão das diretrizes e dos artigos que avaliaram o uso de unidades HEPA para melhorar a limpeza do ar. Essa análise foi feita por diferentes grupos de pesquisadores. Todos os documentos mencionaram que a qualidade do ar dos consultórios odontológicos deve seguir os protocolos da legislação vigente para garantir a segurança dos ambientes. Eles reafirmam que a pandemia da COVID-19 torna imprescindível que os ambientes odontológicos, equipados com ar-condicionado, tenham dispositivos mecânicos de renovação de ar. Uma alternativa para as clínicas de ensino odontológicas brasileiras equipadas comminisplitsou ar-condicionado de janela poderia ser a instalação de exaustores e unidades portáteis de filtro HEPA para fazer as trocas de ar e reduzir os aerossóis no interior dos ambientes (AU).

Cooling Effectiveness of a Data Center Room under Overhead Airflow via Entropy Generation Assessment in Transient Scenarios.

Forecasting data center cooling demand remains a primary thermal management challenge in an increasingly larger global energy-consuming industry. This paper proposes a dynamic modeling approach to evaluate two different strategies for delivering cold air into a data center room. The common cooling method provides air through perforated floor tiles by means of a centralized distribution system, hindering flow management at the aisle level. We propose an idealized system such that five overhead heat exchangers are located above the aisle and handle the entire server cooling demand. In one case, the overhead heat exchangers force the airflow downwards into the aisle (Overhead Downward Flow (ODF)); in the other case, the flow is forced to move upwards (Overhead Upward Flow (OUF)). A complete fluid dynamic, heat transfer, and thermodynamic analysis is proposed to model the system's thermal performance under both steady state and transient conditions. Inside the servers and heat exchangers, the flow and heat transfer processes are modeled using a set of differential equations solved in MATLAB™ 2017a. This solution is coupled with ANSYS-Fluent™ 18, which computes the three-dimensional velocity, temperature, and turbulence on the Airside. The two approaches proposed (ODF and OUF) are evaluated and compared by estimating their cooling effectiveness and the local Entropy Generation. The latter allows identifying the zones within the room responsible for increasing the inefficiencies (irreversibilities) of the system. Both approaches demonstrated similar performance, with a small advantage shown by OUF. The results of this investigation demonstrated a promising approach of data center on-demand cooling scenarios.

Indoor Air Quality in the Hospital: The Influence of Heating, Ventilating and Conditioning Systems

Abstract Clean, fresh air is the most important requirement for good indoor air quality (IAQ) in all buildings, but it is especially important with regard to the environments within hospitals and other healthcare facilities. The literature indicates that buildings with heating, ventilating and air conditioning (HVAC) systems may have an increased risk of sick building syndrome (SBS) and building-related illness (BRI) if they are not well maintained. Microorganisms are brought into hospitals by people, air currents, water, construction materials and equipment. The main objective of this study was to assess the degree of fungal and bacterial contamination in the University Clinical Centre in Banja Luka, which is directly connected to the HVAC system. Airborne bacteria and fungi in the indoor hospital environment were assessed experimentally. Air samples were collected during the winter season. This paper presents the results related to the concentration of microorganisms expressed in colony forming units per cubic metre of air sampled (in CFU/m3) together with the microclimatic parameters temperature and relative humidity. The results of monitoring indicate the effectiveness of HVAC systems in reducing microbiological contamination.