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A relevância da modelagem computacional na otimização dos sistemas de ventilação para a mitigação de poluentes em cozinhas industriais
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Abstract(s)
Este trabalho tem como objetivo avaliar o desempenho de sistemas de ventilação em cozinhas profissionais, integrando resultados experimentais, cálculos normativos e simulações numéricas, de modo a fornecer critérios de projeto mais realistas para a contenção de poluentes e a eficiência energética. O percurso metodológico estruturou-se em três eixos
complementares. No eixo experimental, foi conduzido um ensaio em cozinha-laboratório equipada com hotte de extração, cortinas de ar e sistema de compensação, com grelhador operando em regime intensivo e alimentação controlada de água para geração de vapor. As variáveis de temperatura, humidade relativa, pressão e caudais foram monitorizadas a cada dois segundos em pontos estratégicos, e a taxa de remoção de vapor foi determinada por
análise psicrométrica a partir das propriedades do ar húmido e dos caudais de extração. No eixo normativo, o dimensionamento foi realizado de acordo com a norma EN 16282, aplicando-se o método preliminar baseado na velocidade de captura e o método detalhado, que considera carga térmica, fatores geométricos e indução da pluma. Os resultados forneceram caudais de 3033 e 2844 metros cúbicos por hora, respetivamente, sendo o segundo adotado como referência para as análises. No eixo numérico, desenvolveu-se modelação computacional em plataforma comercial integrada ao ambiente CAD, com malha cartesiana de células cortadas, modelo de turbulência modificado e transporte de espécie para vapor de água. Foram avaliados critérios de convergência espacial e temporal, estabelecendo-se malha de base de 30 milímetros e passo temporal de 0,25 segundos como compromisso entre custo computacional e precisão. A investigação organizou-se em dezasseis cenários: o primeiro validou o modelo CFD
frente ao ensaio físico; os seguintes isolaram o efeito da cortina e da compensação; e os restantes compararam combinações de geometria, extração e emissão normativas e experimentais. A validação demonstrou que o modelo reproduz a evolução temporal e espacial da pluma com fidelidade aceitável, obtendo erro médio de 7,62 por cento e coeficiente de determinação de 0,79. A análise dos dispositivos auxiliares revelou funções complementares: a
compensação moderou picos térmicos, enquanto a cortina organizou o jato e reduziu o espalhamento lateral; a ausência de ambos levou a maior instabilidade, acréscimo da carga térmica acumulada e redução da eficiência de captação para 50 por cento. Nos cenários comparativos, verificou-se que todos apresentaram algum nível de fuga, mesmo quando dimensionados por norma, e que a variabilidade da emissão e os efeitos de parede da geometria real intensificam episódios críticos. Concluiu-se que critérios normativos baseados em limites fixos são insuficientes para representar a complexidade de cozinhas reais, e que abordagens integradas, considerando experimentação, simulação e análise crítica de normas, oferecem subsídios mais robustos para o projeto de sistemas de ventilação, alinhando
segurança, eficiência energética e sustentabilidade.
This dissertation aims to evaluate the performance of ventilation systems in professional kitchens by integrating experimental results, normative calculations, and numerical simulations, in order to provide more realistic design criteria for pollutant containment and energy efficiency. The methodological approach was structured around three complementary axes. In the experimental axis, a test was carried out in a kitchen laboratory equipped with an extraction hood, air curtains, and a compensation system, with a grill operating under intensive regime and controlled water feeding for vapor generation. Temperature, relative humidity, pressure, and airflow variables were monitored every two seconds at strategic points, and the vapor removal rate was determined through psychrometric analysis based on moist air properties and extraction flows. In the normative axis, the design was carried out in accordance with EN 16282, applying the preliminary method based on capture velocity and the detailed method that considers thermal load, geometric factors, and plume induction. The results yielded extraction rates of 3033 and 2844 cubic meters per hour, respectively, with the latter adopted as the reference for analysis. In the numerical axis, computational modeling was developed in a commercial platform integrated into the CAD environment, using a Cartesian cut-cell mesh, a renormalized turbulence model, and species transport for water vapor. Spatial and temporal convergence criteria were evaluated, establishing a base mesh of 30 millimeters and a time step of 0.25 seconds as a compromise between computational cost and accuracy. The investigation was organized into sixteen scenarios: the first validated the CFD model against the physical test; the following isolated the effects of the air curtain and compensation; and the remaining compared combinations of normative and experimental geometry, extraction, and emission. Validation demonstrated that the model reproduced the temporal and spatial evolution of the plume with acceptable fidelity, achieving a mean error of 7.62 percent and a coefficient of determination of 0.79. The analysis of auxiliary devices revealed complementary functions: compensation mitigated thermal peaks, while the curtain organized the jet and reduced lateral dispersion; the absence of both led to greater instability, increased accumulated thermal load, and reduced capture efficiency to 50 percent. In comparative scenarios, it was found that all presented some level of leakage, even when dimensioned by the standard, and that emission variability and wall effects of the real geometry intensified critical episodes. It was concluded that normative criteria based on fixed limits are insufficient to represent the complexity of real kitchens, and that integrated approaches, considering experimentation, simulation, and critical analysis of standards, provide more robust support for the design of ventilation systems, aligning safety, energy efficiency, and sustainability.
This dissertation aims to evaluate the performance of ventilation systems in professional kitchens by integrating experimental results, normative calculations, and numerical simulations, in order to provide more realistic design criteria for pollutant containment and energy efficiency. The methodological approach was structured around three complementary axes. In the experimental axis, a test was carried out in a kitchen laboratory equipped with an extraction hood, air curtains, and a compensation system, with a grill operating under intensive regime and controlled water feeding for vapor generation. Temperature, relative humidity, pressure, and airflow variables were monitored every two seconds at strategic points, and the vapor removal rate was determined through psychrometric analysis based on moist air properties and extraction flows. In the normative axis, the design was carried out in accordance with EN 16282, applying the preliminary method based on capture velocity and the detailed method that considers thermal load, geometric factors, and plume induction. The results yielded extraction rates of 3033 and 2844 cubic meters per hour, respectively, with the latter adopted as the reference for analysis. In the numerical axis, computational modeling was developed in a commercial platform integrated into the CAD environment, using a Cartesian cut-cell mesh, a renormalized turbulence model, and species transport for water vapor. Spatial and temporal convergence criteria were evaluated, establishing a base mesh of 30 millimeters and a time step of 0.25 seconds as a compromise between computational cost and accuracy. The investigation was organized into sixteen scenarios: the first validated the CFD model against the physical test; the following isolated the effects of the air curtain and compensation; and the remaining compared combinations of normative and experimental geometry, extraction, and emission. Validation demonstrated that the model reproduced the temporal and spatial evolution of the plume with acceptable fidelity, achieving a mean error of 7.62 percent and a coefficient of determination of 0.79. The analysis of auxiliary devices revealed complementary functions: compensation mitigated thermal peaks, while the curtain organized the jet and reduced lateral dispersion; the absence of both led to greater instability, increased accumulated thermal load, and reduced capture efficiency to 50 percent. In comparative scenarios, it was found that all presented some level of leakage, even when dimensioned by the standard, and that emission variability and wall effects of the real geometry intensified critical episodes. It was concluded that normative criteria based on fixed limits are insufficient to represent the complexity of real kitchens, and that integrated approaches, considering experimentation, simulation, and critical analysis of standards, provide more robust support for the design of ventilation systems, aligning safety, energy efficiency, and sustainability.
Description
Keywords
Professional ventilation Industrial kitchens Pollutant containment CFD Ventilação profissional Cozinhas industriais Contenção de poluentes