Ventilação natural e desempenho térmico sob diferentes configurações de aberturas em uma sala de aula

In school buildings located in hot tropical areas, it is a common practice to use mechanical climate control systems to avoid heat stress. The use of passive design strategies is of paramount importance for the achievement of thermal comfort with low energy consumption. Hence, buildings’ openings play an important role, as they have an impact on the amount of solar radiation received and on the internal air flow distribution pattern. The objective of this study was to evaluate the thermal performance in classrooms with different window and door model configurations in Vitória/ES and Belém/PA, Brazil. Simulations of thermal performance were conducted to analyse the intensity of thermal discomfort and energy consumption, while the aid of Computational Fluid Dynamics tools enabled the verification of details of the air velocity and temperature fields. The results show that the addition of a ventilated sill increases air velocity at the inlet opening and significantly improves thermal performance in the classroom. The use of brise-soleil reduces energy consumption in the classrooms in Belém and Vitória by up to 50% and 13%, respectively. The study helps in the selection of more efficient openings, adapted to the climatic conditions of each region.Em áreas tropicais quentes, para evitar o estresse térmico, é comum a prática de que os edifícios escolares dependam do uso de sistemas de climatização mecânicos. A utilização de estratégias passivas de projeto, nessas regiões, em busca do conforto térmico com um baixo gasto energético, é de suma importância. Nesse sentido, as aberturas da edificação desempenham um importante papel, pois interferem na quantidade da radiação solar recebida e no padrão de distribuição do fluxo do ar interno. O objetivo desta pesquisa foi avaliar o desempenho térmico em uma sala de aula sob diferentes configurações de modelos de janelas e portas em Vitória, ES, e Belém, PA. A metodologia utilizou simulações de desempenho térmico e de dinâmica dos fluidos computacional para análise da intensidade de desconforto térmico e do consumo energético. Os resultados mostram que a adição do peitoril ventilado aumenta a velocidade do ar na entrada da abertura e melhora significativamente o desempenho térmico na sala de aula. O uso de brise-soleil reduz em até 50% e 13% o consumo energético no ambiente, em Belém e Vitória, respectivamente. O estudo contribui para a seleção de aberturas mais eficientes, adaptadas às condições climáticas de cada região

Ventilação natural e desempenho térmico sob diferentes configurações de aberturas em uma sala de aula

In school buildings located in hot tropical areas, it is a common practice to use mechanical climate control systems to avoid heat stress. The use of passive design strategies is of paramount importance for the achievement of thermal comfort with low energy consumption. Hence, buildings’ openings play an important role, as they have an impact on the amount of solar radiation received and on the internal air flow distribution pattern. The objective of this study was to evaluate the thermal performance in classrooms with different window and door model configurations in Vitória/ES and Belém/PA, Brazil. Simulations of thermal performance were conducted to analyse the intensity of thermal discomfort and energy consumption, while the aid of Computational Fluid Dynamics tools enabled the verification of details of the air velocity and temperature fields. The results show that the addition of a ventilated sill increases air velocity at the inlet opening and significantly improves thermal performance in the classroom. The use of brise-soleil reduces energy consumption in the classrooms in Belém and Vitória by up to 50% and 13%, respectively. The study helps in the selection of more efficient openings, adapted to the climatic conditions of each region.Em áreas tropicais quentes, para evitar o estresse térmico, é comum a prática de que os edifícios escolares dependam do uso de sistemas de climatização mecânicos. A utilização de estratégias passivas de projeto, nessas regiões, em busca do conforto térmico com um baixo gasto energético, é de suma importância. Nesse sentido, as aberturas da edificação desempenham um importante papel, pois interferem na quantidade da radiação solar recebida e no padrão de distribuição do fluxo do ar interno. O objetivo desta pesquisa foi avaliar o desempenho térmico em uma sala de aula sob diferentes configurações de modelos de janelas e portas em Vitória, ES, e Belém, PA. A metodologia utilizou simulações de desempenho térmico e de dinâmica dos fluidos computacional para análise da intensidade de desconforto térmico e do consumo energético. Os resultados mostram que a adição do peitoril ventilado aumenta a velocidade do ar na entrada da abertura e melhora significativamente o desempenho térmico na sala de aula. O uso de brise-soleil reduz em até 50% e 13% o consumo energético no ambiente, em Belém e Vitória, respectivamente. O estudo contribui para a seleção de aberturas mais eficientes, adaptadas às condições climáticas de cada região

Dynamic change of pH in acidogenic fermentation of cheese whey towards polyhydroxyalkanoates production: impact on performance and microbial population

Polyhydroxyalkanoates (PHA) are a sustainable alternative to conventional plastics that can be obtained from industrial wastes/by-products using mixed microbial cultures (MMC). MMC PHA production is commonly carried out in a 3-stage process of acidogenesis, PHA culture selection and accumulation. This research focused on the possibility of tailoring PHA by controlling the acidogenic reactor operating conditions, namely pH, using cheese whey as model feedstock. The objective was to investigate the impact that dynamically varying the acidogenic pH, when targeting different PHA monomer profiles, had on the performance and microbial community profile of the anaerobic reactor. To accomplish this, an anaerobic reactor was continuously operated under dynamic pH changes, ranging from pH 4 to 7, turning to pH 6 after each change of pH. At pH 6, lactate and acetate were the dominant products (41–48% gCOD basis and 22–44% gCOD basis, respectively). At low pH, lactate production was higher while at high pH acetate production was favoured. Despite the dynamic change of pH, the fermentation product composition at pH 6 was always similar, showing the resilience of the process, i.e. when the same pH value was imposed, the culture produced the same metabolic products independently of the history of changes occurring in the system. The different fermentation product fractions led to PHAs of different compositions. The microbial community, analysed by high throughput sequencing of bacterial 16 S rRNA gene fragments, was dominated by Lactobacillus, but varied markedly when subjected to the highest and lowest pH values of the tested range (4 and 7), with increase in the abundance of Lactococcus and a member of the Candidate Division TM7. Different bacterial profiles obtained at pH 6 during this dynamic operation were able to produce a consistent profile of fermentation products (and consequently a constant PHA composition), demonstrating the community’s functional redundancy